Enter0c0cci

Although virulence factors associated with enterococci are a topic of increasing research interest, very little is known about the characteristics that have allowed these organisms to become a prominent cause of nosocomial infections.22 33'28 Compared with other clinically important gram-positive coca, this genus is intrinsically more resistant to the antimicrobial agents commonly used in hospitals and is especially resistant to all currentiy available cephalosporins and aminoglycosides.26 In...

Cultivation Media of Choice

All genera described in this chapter grow on 5 sheep blood and chocolate agars. Most actinobacilli (except A. actinomycetemcomitans and A. ureae) show light growth on MacConkey agar, but the other genera will not grow on this medium. Dysgonomonas capnocytophagoides can be recovered from stool on CVA (cefoperazone-vancomydn-amphotericin B) agar. For recovery of D. capnocytophagoides, this medium, a Campylobacter selective agar, is incubated at 35 C instead of 42 C (preferred for Campylobacter)....

Info

Date compiled from references 6,8,12,15, and 16. v Variable +, > 90 of strains are positive -, > 90 of strains are negative nm, nonmotile p. polar flagella, (+), reaction may be delayed. Only a positive 3-ketolactonate test differentiates this group from Sphingomonaspaudmobilis Colonial pigmentation is critical to separate Chryseobacterium spp. and Empedobacter trews. UNase positive. ' cludes Chryseobacterium gteum, C. Indologenes, and CDC group lib. Table 26-5 Antimicrobial Therapy and...

And Chromobacterium

This isolate could be either Aeromonas or Vibrio. The string test (see Figure 28-3), growth on TCBS, 0129 disk susceptibility, or salt tolerance can be used to separate these genera. The organism produced yellow colonies on TCBS because it was positive for sucrose. It was accurately identified by a commercial system as Vibrio alginolyticus. 2. The most common Vibrio found in the ocean is V alginolyticus. Pseudomonas aeruginosa is most often responsible for external ear infections from fresh...

Expected results

Development of a pink to red color indicates the presence of nitrite, demonstrating the ability of the organism to reduce nitrate to nitrite. If no color results, the organisms may have reduced nitrate beyond nitrite (as in the conventional nitrate test). Add a small amount of powdered zinc to the negative tube. The development of a red color indicates that unreduced nitrate was present in the tube and the organism was nitro-reductase-negative. figure 45-6 Semiquantitative catalase test. The...

Infections in or around Hair Follicles

Folliculitis, furunculosis, and carbundes are localized abscesses either in or around hair follicles. These infections are distinguishable from one another based on size and the extent of involvement in subcutaneous tissues. Table 60-2 summarizes each infection's respective clinical features. For the most part, these infections are predpitated by blockage of the hair follide with skin oils (sebum), or minor trauma resulting from friction BOX 60-1 Resident Microbial Flora of the Skin Other...

Erysipelas and Cellulitis

As previously mentioned, diagnosis of erysipelas and cellulitis can generally be made on a clinical basis. The value of needle aspiration for the bacteriologic diagnosis of these infections has not been clearly demonstrated, particularly in adults. Of note, a higher percentage of positive cultures of soft tissue aspirates along the advancing margin of erythema using a 22- or 23-gauge needle attached to a 3- or 5-mL syringe may be achieved in children with cellulitis.5 If received by the...

General characteristics

At one time, most of the species belonging to the genera Brevundimonas, Burkholderia, Ralstonia, and Acidovorax were all members of the genus Pseudomonas. Organisms in these genera share many similar characteristics. They are aerobic, straight, and slender gram-negative bacilli whose cells range from 1 to 5 nm in length and 0.5 to 1 (im in width. All species except B. mallei are motile. Members of these genera use a variety of carbohydrate, alcohol, and amino acid substrates as carbon and...

Iai

Figure 44-7 Clostridium petfrmgens on anaerobic blood agar. Note Figure 44-8 Gram stain of Fusobacterium nucleatum subsp. double zone of beta hemolysis. 1, First zone 2, second zone. nudeatum. Note pointed ends. (Courtesy Anaerobe Systems, Morgan Hill, Calif.) Figure 44-7 Clostridium petfrmgens on anaerobic blood agar. Note Figure 44-8 Gram stain of Fusobacterium nucleatum subsp. double zone of beta hemolysis. 1, First zone 2, second zone. nudeatum. Note pointed ends. (Courtesy Anaerobe...

Wjw

Within the life cycle (see Figure 49-77), free-swimming cercariae attach to and penetrate unbroken skin of the human host. In temperate zones, such as the Great Lakes area, cercariae of other bird or animal nematodes can penetrate human skin and cause a strong local reaction (swimmer's itch), although they do not complete the life cycle. The filarial worms are long, thin nematodes that inhabit* the lymphatic system and the subcutaneous and deep connective tissues (see Figure 49-78). Most...

Incubation Conditions and Duration

The growth of all genera discussed in this chapter occurs best at 35 C and in the presence of increased C02. Therefore 5 sheep blood and chocolate agars should be incubated in a C02 incubator or candle jar. In addition, Actinobacillus and Cardiobacterium grow best in conditions of elevated moisture a candle jar with a sterile gauze pad moistened with sterile water is ideal for this purpose. Capnocytophaga will grow anaerobically but will not grow in ambient air. Even when optimum growth...

Pathogenesis And Spectrum Of Disease

Aspergillus species are capable not only of causing disseminated infection, as is seen in immunocompromised patients, but also of causing a wide variety of other types of Infections, including a pulmonary or sinus fungus ball, allergic bronchopulmonary aspergillosis, external otomycosis (a fungus ball of the external auditory canal), mycotic keratitis, onychomycosis (infection of nail and surrounding tissue), sinusitis, endocarditis, and central nervous system infection. Most often,...

Api20c Aux Yeast System

The API-20C AUX yeast identification system (bio-Merieux, Durham, NC) has perhaps the most extensive computer-based data set of all commercial systems available. The system consists of a strip that contains 20 microcupules, 19 of which contain dehydrated substrates for determining utilization profiles of yeasts. Reactions are compared with growth in the first cupule, which lacks a carbohydrate substrate. Reactions are read and results are converted to a seven-digit biotype profile number. Most...

Automated and Semiautomated Systems

Automated screening systems offer the promise of a large throughput with minimal labor and a rapid turnaround time compared with conventional cultures. However, these advantages may be offset by a substantial cost for the instrumentation. Often these costs can be justified only in laboratories that receive many specimens. Several automated or semiautomated urine screening systems that are either bacterial growth independent or dependent are commercially available. By examining images of...

1

Of interest (i.e., lysine, ornithine, or arginine), and a pH indicator. Organisms are inoculated into the tube medium that is then overlaid with mineral oil to ensure anaerobic conditions. (See Chapter 13) Early during incubation, bacteria utilize the glucose and produce acid, resulting in a yellow coloration of the pH indicator. Organisms that can decarboxylate the amino acid then begin to attack that substrate and produce the amine product, which increases the pH and changes the indicator...

Epidemiology spectrum of disease and antimicrobial therapy

Fee organisms listed in Table 33-1 are part of the formal flora of humans and other animals. As such, V generally are of low virulence and, except for those species associated with periodontal infections. usually only cause infections in humans after introduction into sterile sites following trauma such as bites or manipulations in the oral cavity.1,6'9 The types of infections caused by these bacteria vary from periodontitis to endocarditis (Table 33-2). Three of these organisms, Actinobadllus...

Culture Media And Incubation Requirements

Any of a number of fungal culture media are satisfactory for use in the clinical microbiology laboratory. Most are adequate for the recovery of fungi, and selection is usually left up to each individual laboratory director. Table 50-6 lists various media and the indications for their use. For optimal recovery a battery of media should be used, and the following are recommended 1. Media with and without cycloheximide 2. Media with and without an antibacterial agent. This is for specimens that...

Bone

Diagnosis of certain diseases, including brucellosis, histoplasmosis, blastomycosis, tuberculosis, and leishmaniasis, can sometimes be made only by detection of the organisms in the bone marrow. Brucella spp. can be isolated on culture, as can fungi, but parasitic agents must be visualized in smears or sections made from bone marrow material. Of importance, many of the etiologic agents associated with disseminated infections in patients infected with the human immunodeficiency virus (HTV) may...

Additional Reading

Enterobacter Citrobacter, Serratia, Plesio-monas, and other Enterobaderiaceae, In Murray PR, Baron EJ, Jorgensen JH, et al, editors Manual of clinical microbiology, ed 8, Washington, DC. 2003, ASM Press, Balows A, Truper HG, Dworkin M, et al editors The pro. karyotes. A handbook on the biology of bacteria ecophysiolog isolation, identification, applications, ed 2, New York, 1992, Springer-Verlag. Bockem hl J, Wang JD Yersinia. In Murray PR, Baron EJ, Jorgensen JH, et al,...

Definitive Identification

Various techniques are available for definitive identti fication of anaerobic bacteria. These methods may include the following Pre-reduced anaerobically sterilized (PRAS) bi* chemicals Miniaturized biochemical systems (e.g., API 20Ar bioMerieux, Inc., St. Louis, Mo) Rapid, preformed enzyme detection panels (e& Anldent, bioMerieux, Inc. RapID-ANA II, Ren Inc., Lenexa, Kan BBL Brand Crystal Anaerobe DXj Becton Dickinson and Company Rapid Anaerot Identification Panel, Dade MicroScan, West...

Acquired Resistance Patterns Common To Local Microbial Flos

If resistance to a particular agent Is common, the utility of the agent may be sufficiently limited so that routine testing is not warranted and only more potent antimicrobials are included in the test battery. Conversely, more potent agents may not need to be in the test battery if susceptibility to less potent agents is highly prevalent. ANTIMICROBIAL SUSCEPTIBILITY TESTING METHOD USED Depending on the testing method, some agents do not reliably detect resistance and should not be included in...

Cez

Figure 12-5 A, By the disk diffusion method, antibiotic disks are placed on the surface just after the agar surface was inoculated with the test organism. B, Zones of growth inhibition around various disks are apparent following 16 to 18 hours of incubation. Figure 12-6 Example of a regression analysis plot to establish zone-size breakpoints for defining the susceptible, intermediate, and resistant categories for an antimicrobial agent. In this example, the maximum achievable serum...

J

Figur 10-6 Indirect fluorescent antibody tests for Toxoplasma gondii, IgG antibodies. A, Positive reaction. Br Negative reaction. (Courtesy Meridian, Cincinnati, Ohio.) human immunodeficiency virus (HIV), rubella virus (both IgG and IgM), mycoplasmas, chlamydias Borrelia burgdorferi, Entamoeba histolytica, T. gondii, and many other agents. The introduction of membrane-bound ELISA components has improved sensitivity and ease of use dramatically. Slot-blot and dot-blot assays force the target...

Advantages And Examples Of Commercial System Designs

Commercially available identification systems have largely replaced compilations of conventional test media and substrates prepared in-house for bacterial identification. This replacement has mostly come about because the design of commercial systems has continuously evolved to maximize the speed and optimize the convenience with which all four identification components shown in Figure 7-17 can be achieved. Because laboratory workload has increased, conventional methodologies have had...

Food and Water Borne Outbreaks

The Centers for Disease Control and Prevention report that more than 12,000 cases of food-borne illness occur in the United States each year. Because most of these illnesses are not reported, some estimate that millions of cases occur annually. Eating raw or undercooked fish, shellfish, or meats, and drinking unpasteurized milk increases the risks of certain bacterial, parasitic and viral infections. Many food-borne outbreaks can be traced to poor hygienic practices of food handlers such as not...

Identification Methods

A wide variety of methods and criteria are used to establish a microorganism's identity. These methods usually can be separated into either of two general categories genotypic characteristics and phenotypic characteristics. Genotypic characteristics relate to an organism's genetic makeup, including the nature of the organism's genes and constituent nucleic acids (see Chapter 2 for more information about microbial genetics). Phenotypic characteristics are based on features beyond the genetic...

Qsm

Characteristics of acquired resistance 1. Enzymatic degradation or modification of the antimicrobial agent 2. Decreased uptake or accumulation of the antimicrobial agent 3. Altered antimicrobial target 4. Circumvention of the consequences of antimicrobial action 5. Uncoupling of antimicrobial agent-target interactions and subsequent effects on bacterial metabolism 6. Any combination of mechanisms 1 through 5 Figure 11-8 Overview of common pathways bacteria use to effect antimicrobial...

Direct Visual Examination

All material submitted for culture should always be smeared and examined directly by Gram stain or Other appropriate techniques. In bacterial conjunctivitis, polymorphonuclear leukocytes predominate in viral infection, the host cells are primarily lymphocytes and monocytes. Specimens in which chlamydia is suspected can be stained immediately with monoclonal antibody conjugated to fluorescein for detection of elementary bodies or inclusions. Using histologic stains, basophilic intracytoplasmic...

The Spirochetes

She acquired the disease most likely from the bite of the nymphal form of the Ixodes tick infected with Borrelia burgdorferi. Even though symptoms were not manifest for a few weeks, her description of the initial lesion is consistent with erythema migrans (see Figure 48-3). 2. IFA tests are very sensitive to detect antibodies to B. burgdorferi, but they are known to have a high false-positive rate. Initially the patient's presentation combined with the positive IFA seemed to be enough to treat...

Organism Identification Using Phenotypic Criteria

Phenotypic criteria are based on observable physical or metabolic characteristics of bacteria, that is, identification is through analysis of gene products rather than through the genes themselves. The phenotypic approach is the classic approach to bacterial identification, and most identification strategies are still based on bacterial phenotype. Delineation of some characteristics may require subcellular analysis involving sophisticated instrumentation (e.g., high-performance liquid...

Sinus Tract and Fistulas

Sometimes, a deep-seated infection beneath the skin and subcutaneous soft tissue spontaneously drains itself externally by way of a sinus (channel or cavity) to the skin's surface. Draining sinus tracts are most often associated with a chronic osteomyelitis. Unfortunately, this type of drainage does not usually cure the underlying process, and such sinuses themselves tend to be chronic. The organisms most often involved in sinuses with an underlying osteomyelitis are S. aureus, various...

Inhouse Qa Audits

A facility that does not subscribe to the Q-Probe program may select topics for audits through suggestions from the medical, nursing, or pharmacy staffs complaints from the medical or nursing staff or deficiency or observation noted in the laboratory. Physicians may suggest an audit to measure the transcription accuracy of their orders by nursing unit clerical personnel Nursing administrators may suggest an audit of contaminated urine cultures to access the compliance of the nursing staff in...

Interpretation

Although isolation of M. tuberculosis complex organisms represents infection, the clinician must determine the clinical significance of isolating an NTM in most cases in other words, does the organism represent mere colonization or significant infection Because these organisms greatly in their pathogenic potential, can colonize individual without causing infection, and are ubiquitous in the environment, interpretation of a positive NTM culture is complicated. Therefore, the American thoracic...

Interpretation of Blood Culture Results

Because of the increasing incidence of blood vascular infection caused by bacteria that are normally considered nonvirulent, indigenous microflora of a healthy human host, interpretation of the significance of growth of such bacteria in blood cultures has become increasingly difficult. On one hand, contaminants may lead to unnecessary antibiotic therapy, additional testing and consultation, and increased length of hospital stay. Costs related to false-positive blood culture results (i.e...

Interpretation Of Laboratory Test Results

Interpretation of laboratory test results must be based on knowledge of the normal viral flora in the site sampled, the clinical findings, and the epidemiology of viruses. Serologic testing, in addition to virus detection tests, may be needed to support or refute the association of a virus isolate with a disease state. In general, the detection of any virus in host tissues, CSF, blood, or vesicular fluid is significant. Recovery of adenovirus or mumps virus in urine is usually diagnostic of...

Interpreting And Recording Results

Egg media should have been inoculated with approximately 104. 103, and 102 organisms, respectively. The first dilution should produce semiconfluent growth, and the second and third dilutions should produce countable colonies in each bottle. Because of the retrospective nature of these determinations, dose comparisons must be made between current and previous results to note trends or developing delidendes. Failures may be the result of faulty media, lethal effects of decontamination and...

Kjz

L wenstein-Jensen (L-J) L-J with RNA L-J with pyruvic acid Middlebrook 7H10 If growth occurs, confirm by AFB smear Mycobacterium Growth Indicator Tube. Figure 45-1 A flowchart for specimen processing for isolation of mycobacteria. Digestion-decontamination procedures should be as gentle as possible, with no more than an overall contamination rate of 5 .5 Overview. Commonly used digestion e ntamina-tion methods are the sodium hydroxide (NaOH) method the Zephiran-trisodium phosphate method, and...

Xvp

Figure 51 -22 Shell vial cell culture tubes and stained coverslips. At the bottom of each shell vial tube under culture medium is a round coverslip with a cell monolayer on the top surface. After incubation, the coverslip is removed, stained, and placed on a microscope slide for fluorescence viewing. Note that two stained coverslips are on the glass slide. ture. It is best used for viruses that require relatively long incubation before producing CPE, such as CMV and VZV. The advantage of shell...

J11111111111illj1l

Figure 2-6 Overview of translation in which mRNA serves as the template for the assembly of amino acids into polypeptides. The three steps include initiation (A), elongation (B and C), and termination (not shown). (i.e., are not transcribed and therefore are not expressed) in the presence of those products. This strategy avoids waste and overproduction of products that are already present in sufficient supply. In this system the product acts as a co-repressor that forms a complex with a...

Jllu

Positive hybridization detected by visualization of color Hybridized duplex labeled with acridinium Positive hybridization detected by capturing emission of light Figure 8-2 Reporter molecule labeling of nucleic acid probes and principles of hybridization detection. Use of probes labeled with a radioactive reporter, with hybridization detected by autoradiography (A) probes labeled with biotin-avidin reporter, with hybridization detected by a colorimetric assay (B) probes labeled with...

L

Plasmodium vlvax, P. falciparum, P. ovale, and P. malariae are definitely pathogenic tar humans, malaria with P. falciparum being one of the leading causes of death in endemic areas although the host can develop antibody, protection is strain specific and short-lived Malaria can cause a range of symptoms, with life-threatening illness caused by P. falciparum symptoms Include fever, chills, nausea, central nervous system (CNS) symptoms, etc. Babesia infections mimic those seen with malaria,...

Laboratory Considerations

Clostridium botulinum produces three toxins, all of which can be fatal even in small doses, In addition, this stria anaerobe is difficult to isolate. The diagnosis is made by testing tissue or patient's serum in a mouse bioassay. Mice are inoculated with the specimen in combination with various antitoxins. Persons who work with the organism are given botulism toxoid vaccination so that they will be immune to the effects of the toxin. Our patient was given antitoxin against all three botulism...

Laboratory Design With Respect To Safety

Laboratory safety is discussed in depth in Chapter 4. However, a few points are worth repeating here since they pertain to laboratory design. The emergency shower and eye wash stations should be centrally located. The standard for the location of these units is the same, that is, within 10 seconds and 100 feet of each work area. Cold water is used for emergency flushing of eyes and skin because it will do the following Slow the reaction rate of the splashed chemical Constrict blood vessels and...

Laboratory Diagnosis

Specimen Collection, Transport, and Processing Clinical specimens frequently submitted to the laboratory for direct examination and culture indude blood, which has been collected in a lysis-centrifugation blood culture tube (Isolator Wampole Laboratories, Cranbury, NJ), as well as aspirates and or tissue specimens (e.g lymph node, spleen, or cutaneous biopsies). There are no special requirements for specimen collection, transport, or processing of the organisms discussed in this chapter. Refer...

Laboratory Diagnosis Of Clostridium DctcifAssociated Diarrhea

The definitive diagnosis of C. diffidle-assodated diarrhea is based on clinical criteria combined with laboratory testing. Visualization of a characteristic pseudomembrane or plaque on endoscopy is diagnostic for pseudomembranous colitis and, with the appropriate history of prior antibiotic use, meets the criteria for diagnosis of antibiotic-associated pseudomembranous colitis. No single laboratory test will establish the diagnosis unequivocally. Three tests are currently available for routine...

Laboratory diagnosis of mycobacterial infections

Specimens received by the laboratory for mycobacterial smear and culture must be handled in a safe manner. Tuberculosis ranks high among laboratory-acquired infections. Therefore, laboratory and hospital administrators must provide laboratory personnel with facilities, equipment, and supplies that will reduce this risk to a minimum All tuberculin-negative personnel should be skin-tested at least every year. Biosafety Level 2 practices, containment equipment, and facilities for preparing...

Laboratory Environment

The biohazard symbol should be prominently displayed on laboratory doors and any equipment (refrigerators, incubators, centrifuges) that contain infectious material. The air-handling system of a microbiology laboratory should move air from lower to higher risk areas, never the reverse. Ideally, the microbiology laboratory should be under negative pressure, and air should not be recirculated after passing through microbiology (see Chapter 62 for a more detailed discussion of negative pressure in...

Laboratory Methods and Strategies for chapter Antimicrobial Susceptibility Testing

As discussed in Chapter 11, most clinically important bacteria are capable of acquiring and expressing resistance to antimicrobial agents commonly used to treat the infections they cause. Therefore, once an organism is isolated in the laboratory, characterization frequently includes tests to detect antimicrobial resistance. That is to say that in addition to the organism's identification, its antimicrobial susceptibility profile is often another key component of the clinical laboratory report...

Laboratory Methods for Diagnosis chapter JO of Parasitic Infections

Entamoeba glngivalis Flagellates Trichomonas vaginalis Trichomonas tenax Coccidia and Microsporidia (Other Body Sites) Coccidia Toxoplasma gondii Microsporidia Nosema Brachiota Maforma Pleistophora Trachipleistophora Encephalitozoon Enterocytozoon Mterospondium* Helminths Nematodes (Roundworms) Intestinal Ascaris lumbricoides Enterobius vermicularis Ancylostoma duodenale Necatoramericanus Strongyloides stercoralis Trichostrongylus spp. Trichuristrichiura Capillaria philippinensis Tissue...

Laboratory Methods For Diagnosis Of Parasitic Infections

If no RBCs are seen in the cytoplasm and the trophozoites measure s. 12 jim, Entamoeba histolytica (true pathogen) cannot be differentiated from nonpathogenic Entamoeba dispar. Currently, there are immunoassays available that will confirm organisms in the Entamoeba histolytica E. dispar group in the specimen, as well as one immunoassay that will confirm the presence of the pathogen E. histolytica. 2. It is Important for the physician to recognize that a report of E. histolytica E. dispar does...

Laboratory Methods In Basic Mycology

The organism is Blastomyces dermatitidis. This organism may be rapidly and accurately identified in the specimen upon direct examination, by the experienced microscopist. The characteristic features are the moderate size and the pathognomonic broad-base bud. The calcofluor white KOH is a rapid and useful method for detecting and, in some instances, such as this one, identifying fungi in clinical specimens. 2. This organism is one of the systemic dimorphic molds. These organisms have a yeast or...

Laboratory Methods In Basic Virology

L Common viruses that cause disease this serious in young adults include influenza A and adenovirus. Other viruses that should be considered if implicated by epidemiologic investigation are the hantaviruses (e.g., sin nombre virus). 2. Sputum and upper respiratory tract secretions are excellent specimens for the detection of influenza and adenoviruses however, adenoviruses may be present in the absence of overt disease. Specimens collected by invasive techniques, such as broncho-alveolar lavage...

Laboratory Physical Design chapter Management and Organization

Microbiology laboratories operate to various venues. During the 1990s the trend changed from centralized facilities that operate from large hospital, public health, or independent laboratories to decentralized facilities that operate outside of a main laboratory but may still be within the physical hospital facility. Decentralized testing is also known as alternatesite testing. Alternate-site testing is performed in physician office laboratories (POLs), in ancillary outpatient hospital clinics,...

Laboratory Response Network

Because communication between clinical and public health laboratories is so critical in the post-2001 era, CDC created an organizational structure whereby isolates and lines of communication flow freely among members.4 The Laboratory Response Network (LRN) was originally designed as a four-tier system. Clinical (Level A) laboratories were at the bottom of a triangle, sending specimens to a Level B (local public health laboratory) or Level C (state public health laboratory) for confirmation....

Larynaotracheobronchitis

Another clinical syndrome closely related to laryngitis is acute laryngotracheobronchitis, or croup. Croup is a relatively common illness in young children, primarily those younger than 3 years of age. Of significance, croup can represent a potentially more serious disease if the infection extends downward from the larynx to involve the trachea or even the bronchi. Illness is charactenzed by variable fever, inspiratory stridor (difficulty in moving enough air through the larynx), hoarseness,...

Less Common Or Prevalence Not Established

Table 21 -2 Species Included in the Genera Rhodococcus, Gordonia, and Tsukamurella fast, branching, filamentous bacteria that can fragment into rods and cocci. The extent of acid-fastness is dependent on the amount and complexity of mycolic acids in the organism's cell envelope and on culture conditions. The differentiation of these three genera, as well as spedes identification, is difficult.3,9-12 In particular, the genus Rhodococcus consists of a very diverse group of organisms in terms of...

Limitations

This method cannot be used on fresh clinical specimens. It is for culture identification only. The use of nucleic add probes with cultures grown on a blood-containing medium is unsatisfactory for testing, in that hemin will chemilu-minesce and yield a false-positive result. first of these to be released and is the representative compound of this group. Caspofungin. Caspofungm is fungiddal against Candida spp., induding spedes that are or may be resistant to fluconazole, such as C. krusei and C....

Limitations Of Standardization

Although standardization of in vitro conditions is essential, the use of standard conditions imparts some limitations. Most notably, the laboratory test conditions in no way mimic the in vivo environment at the infection sites where the antimicrobial agent and bacteria will actually interact. Factors, such as bacterial inoculum size, pH, cation concentration, and oxygen tension (i.e., atmosphere), can differ substantially depending on the site of infection. Because of the lack of correlation...

Litial Processing

Initial processing of CSF for bacterial, fungal, or parasitic studies includes centrifugation of all specimens greater than 1 mL in volume for at least 15 minutes at 1500x g. Specimens in which cryptococci or mycobacteria are suspected must be handled differently. (Discussions of techniques for culturing CSF for mycobacteria and fungi are found in Chapters 45 and 50, respectively.) The supernatant is removed to a sterile tube, leaving approximately 0.5 mL of fluid in which to suspend the...

Lysis Centrifugation

Wampole Tubes

The lysis centrifugation system commercially available is the Isolator (Wampole Laboratories, Cranbury, NJ), The Figure 52-6 Lysis centrifugation blood culture (Isolator System, Wampole Laboratories) uses vacuum-draw collection tubes with a lysing agent and special apparatus (Isostat Press) to facilitate removal of the supernatant without use of needles. (Courtesy Wampole Laboratories, Cranbury, NJ.) Figure 52-5 Becton Dickinson Septi-Chek pediatric size bipbasic blood culture bottle. The...

Todd Hewitt Broth With Gentamicin And Nalidixic Acid Laboratory

Figure 17-1 Chains of streptococci seen in Gram stain prepared from broth culture. Figure 17-1 Chains of streptococci seen in Gram stain prepared from broth culture. ments of the genera in this chapter are noted in Tables 17-3 and 17-4. Except for Abiotrophia and Granulicatella, the organisms discussed in this chapter will grow on standard laboratory media such as 5 sheep blood and chocolate agars. They will not grow on MacConkey agar but will grow on gram-positive selective media such as CNA...

Mailing Biohazardous Materials

In March 2005 the requirements for packaging and shipping biologic material were significantly revised in response to the international community's desire to ensure safe and trouble-free shipment of infectious material while attempting to be more reasonable. Before this date, clinical specimens submitted for infectious disease diagnosis as well as isolates of any microotganism were considered an infectious substance and packaged and labeled under UN6.2 dangerous goods regulations. Now, only...

Media Of Choice

The primary plating media for inoculating anaerobic specimens can be picked from the media listed in Table 43-4. In general they include a nonselective anaerobic blood agar and one or all of the following selective media Bacteroides bile esculin agar (BBE), laked kanamycin-vancomycin blood agar (LKV), or anaerobic phenylethyl alcohol agar (PEA). In addition, aerobic 5 sheep blood agar, chocolate agar, and MacConkey agar are set up because most anaerobic infections are polymicrobic and may...

Meningitis And Other Infections Of The Central Nervous System

This organism is most likely Neisseria meningitidis, which is oxidase-positive. To confirm the identification, numerous commercial rapid tests are available. They take advantage of the fact that this species ferments maltose and glucose but not lactose. Other members of the genus have different patterns of fermentation. Some systems rely on specific enzyme production by the organism to identify Neisseria to the species level (see Table 13-1). Because of the importance of correctly diagnosing...

Method A

Inoculate one M. hominis agar plate and two M, hominis broth tubes, one broth containing phenol red indicator and one without the possibly inhibitory phenol red, each with 0.1-mL specimen from transport media. 3. Incubate broths in tightly sealed test tubes for 5 days. If the phenol red-containing broth changes color to red A 29-year-old previously healthy female presented with a productive cough, fever to 102 F, and severe headache. She had cervical adenopathy (swollen glands), although she...

Method

Allow the three cartridges of disks to equilibrate to room temperature. 2. Transfer a portion of one colony to an anaerobic blood agar plate. Streak the first quadrant several times to produce a heavy lawn of growth, and then streak die other quadrants for isolation. 3. Place the colistin, kanamycin, and vancomycin disks in the first quadrant, well separated from each other (Figure 44-13). 4. Incubate the plates anaerobically for 48 hours at 35 C. Special potency antibiotic and other . disks....

Methods and Strategies

Rationale for a method of organism identification_ Deciding how to teach microbiology in a manner that is both comprehensive and yet understandable is difficult. Most microbiology text chapters are organized by genus name and provide no obvious approach as to how to work up a clinical isolate. Some texts have flowcharts containing algorithms for organism workup many of these, however, are either too broad to be helpful (e.g., gram-positive vs. gramnegative bacilli) or too esoteric (e.g.,...

Methods Of Disinfection

The three physical methods of disinfection are Boiling at 100 C for 15 minutes, which kills vegetative bacteria Pasteurizing at 63 C for 30 minutes or 72 C for 15 seconds, which kills food pathogens Using nonionizing radiation such as ultraviolet (UV) light UV rays are long wavelength and low energy. They do not penetrate well and organisms must have direct surface exposure, such as the working surface of a BSC, for this form of disinfection to work. ' Chemical disinfectants comprise many...

Methods That Directly Measure Antimicrobial Activity

Methods that directly measure antimicrobial activity involve bringing the antimicrobial agents of interest and the infecting bacterium together in the same in vitro environment to determine the impact of the drug's presence on bacterial growth or viability. The level of impact on bacterial growth is measured and interpreted so that the organism's resistance or susceptibility to each agent tested can be reported to the clinician. Direct measures of antimicrobial activity are accomplished using...

Microorganism Colonization Of Host Surfaces

Once a microbe and the human host are brought into contact, the outcome of the encounter depends on what happens during each step of interaction (see Figure 3-1), beginning with colonization. The human host's role in microbial colonization, defined as the persistent survival of microorganisms on a surface of the human body, is dictated by the defenses that protect vital internal tissues and organs against microbial invasion. The first defenses are the external and internal body surfaces that...

Miscellaneous

Unusual agents and those that have not been cultured, such as the mycobacteria that may be associated with Crohn's disease and the bacterium associated with Whipple's disease, identified by molecular methods as a new agent, Trophyrema whipplei, are also candidates as etiologic agents of GI disease. Occasionally, stool cultures from patients with diarrheal disease yield heavy growth of organisms such as enterococci, Pseudomonas spp., or Table 59-4 General Characteristics of the Common Agents of...

Miscellaneous Infections

Infections of the male prostate, epididymis, and testes are usually bacterial. In younger men, chlamydiae predominate as the cause of epididymitis and possibly of prostatitis. Urine or discharge collected via the urethra is the specimen of choice unless an abscess* is drained surgically or by needle and syringe. The first few milliliters of voided urine may be collected before and after prostatic massage to try to pinpoint the anatomic site of the infection. Cultures are inoculated to support...

Miscellaneous Matters

Blood drawn for culture must not be allowed to clot. If bacteria become entrapped within a clot, their presence may go undetected. Thus, blood drawn for culture may be either inoculated directly into the blood culture broth media or into a sterile blood collection tube containing an anticoagulant for transport to the laboratory for subsequent inoculation. Heparin, ethylenediaminetetraacetic acid (BDTA), and citrate inhibit numerous organisms and are nor recommended for use....

Miscellaneous Specimen Types

Other specimens that may be obtained for diagnosis of GI tract infection include duodenal aspirates (usually for detection of Giardia or Strongyloides), which should be examined immediately by direct microscopy for the presence of motile protozoan trophozoites, cultured for bacteria, and placed into polyvinyl alcohol (PVA) fixative for subsequent parasitic examination. The laboratory should be informed in advance that such a specimen is going to be collected so that the specimen can be...

Molecular Biological Techniques

The development of amplification techniques has led to numerous publications for the direct detection of many enteric pathogens, including all major organism groups bacteria, viruses, and parasites. Probes for Salmonella Shigella, EHEC, and Yersinia are being evaluated. A disadvantage with probe technology is that the organism itself is not available for susceptibility testing, which is important for certain bacterial pathogens (e.g., Shigella) for which susceptibility patterns vary.

Molecular Identification

The genus Mycobacterium consists of a diverse group of acid-fast bacilli. As previously mentioned, conventional methods for identification of these organisms are well established and inexpensive, but these methods are time-consuming and labor-intensive, and they provide inconclusive results, often leading to species identifications based on a best-fit approach. The introduction of molecular methods has revolutionized the identification of mycobacteria by reducing time to identification as well...

Monoclonal Antibodies

The ability to create an immortal cell line producing large quantities of a completely characterized and highly specific antibody, known as a monoclonal antibody, has revolutionized immunologic testing. Monoclonal antibodies are produced by the offspring (clones) of a single hybrid cell, the product of fusion of an antibody-producing plasma B cell and a malignant antibody-producing myeloma cell. One technique for the production of such a clone of cells, called hybridoma cells, is illustrated in...

Moraxella

It is possible from the description that this could be one the microorganisms discussed in Chapter 33, known as the HACEK group. However, most members of the HACEK group are glucose-fermenters. Eikenella corrodens is the exception. We have already discussed the use of Andrade's glucose medium supplemented with rabbit serum or plasma to grow these bacteria and demonstrate their fermentation properties (see Chapter 23 Case Study). When this test is set up, a nitrate reduction test is also...

Mrect detection methods

Other than Gram stain of patient specimens, there are 10 specific procedures for the direct detection of these organisms in clinical material. Acinetobacter spp. are plump coccobacilli that tend to resist alcohol decolo-rization they may be mistaken for Neisseria spp. The Bordetella spp. are coccobacilli or short rods. S. malto-philia, P. oryzihabitans, and P. luteola are short to medium-size straight rods. CDC group NO-1 are coccoid to medium-size bacilli. Table 23-3 Colonial Appearance and...

Mucous Membrane Protective Activity Structures

Mucosal cells Rapid sloughing for bacterial removal Tight intercellular junctions prevent bacterial penetration Goblet cells Mucus production Protective lubrication of cells Bacterial trapping Contains specific antibodies with specific activity against bacteria Provision of antibacterial substances to mucosal surface Lysozyme degrades bacterial cell wall iron supply Lactoperoxidase production of substances toxic to bacteria Mucosa-associated Mediates specific responses against lymphoid tissue...

Nd

U to data v, variable +, > 90 of strains positive (+), > 90 of strains positive but reai quire a drop of rabbit serum on the slant or a heavy inoculum, fj ay require the addition of 1 to 2 drops rabbit serum per 3 mL of fermentation broth to st Pirate is usually reduced to gas. delayed (i.e., 2 to 7 days) -, > 90 of

Necrotizing Fasciitis

Necrotizing fasciitis is a serious infection that occurs relatively infrequently. The basic pathology is infection of the fascia overlying muscle groups, often with involvement of the overlying soft tissue. At the fascial level, no barrier exists to spread of infection, so fas ciitis may extend widely and rapidly to involve huge areas of the body in short periods. This process, once known as hospital gangrene, typically involves group A streptococci or S. aureus. Necrotizing fasciitis also...

New test SEJo95x i 0

95 CONFIDENCE INTERVAL Currant Test 0.90 - (1.96 x 0.05) to 0.90 + (1.96 x 0.05) 0.90-0.10 to 0.90 + 0.10 0.80 to 1.00 The new test would be acceptable (validated) at the 95 CI. 0.95 - (1.96 x 0.04) to 0.35 + (t.96 x 0.04) 0.95 - 0.08 to 0.95+ 0.08 0.87 to 1.03 standard error (SE) and sensitivity of the tests must be known (Box 62-2). The standard error can be calculated using the following formula where p sensitivity of the test where n sample size where J square root The example in Box 62-2...

Normally Sterile Body Fluids Bone And Bone Marrow And Solid Tissues

This organism likely is Peptostreptococcus spp., because it did not grow aerobically. This genus has been subdivided into a number of new genera. However, most laboratories use the general genus name Peptostreptococcus spp., because it is not clinically important to separate the anaerobic gram-positive cocci further. 2. The patient is likely infected with her own skin flora, which was introduced at the time of the surgery. Because of the placement of a foreign object, her body was unable to...

Nucleic Acid Amplification

Molecular techniques, such as conventional and realtime PCR, have been used to detect M. tuberculosis directly in clinical specimens two kits are available commercially that are approved by the FDA. The Amplicor Mycobacterium tuberculosis test (Roche Diagnostic Systems, Branchburg, NJ) uses PCR to detect M. tuberculosis directly in respiratory specimens the Amplified Mycobacterium tuberculosis Direct Test (Gen-Probe, San Diego, Calif) is based on ribosomal RNA amplification. The Roche assay...

Nucleic Acid Hybridization Methods

Hybridization methods are based on the ability of two nucleic acid strands that have complementary base sequences (i.e are homologous) to specifically bond with each other and form a double-stranded molecule, or duplex or hybrid. This duplex formation is driven by the consistent manner in which the base adenine always bonds to thymine, while the bases guanine and cytosine always form a bonding pair (see Figure 2-2). Because hybridization requires nucleic acid sequence homology, a positive...

Number of Blood Cultures

Because periodicity of microorganisms in the bloodstream may be characteristic for some diseases, continuous for some and random in others, these patterns of bacteremia must be considered in establishing standards for the timing and number of blood cultures. If the volume of blood is adequate, usually two or three blood cultures are sufficient to achieve the optimum blood culture sensitivity. In patients with endocarditis who have not received antibiotics, a single blood culture is positive in...

Opper Respiratory Tract

Diseases of the upper respiratory tract are named according to the anatomic sites involved. Most of these infections are self-limiting and most are caused by viruses. Acute laryngitis is usually associated wrth the common cold or influenza syndromes. Characteristically, patients complain of hoarseness and lowering or deepening of the voice. Acute laryngitis is generally a benign illness. Acute laryngitis is caused almost exclusively by viruses. Although numerous viruses can cause laryngitis...

Organism Identification Using Genotypic Criteria

Genotypic identification methods involve characterization of some portion of a bacterium's genome using molecular techniques for DNA or RNA analysis. This usually involves detecting the presence of a gene, or a part thereof, or an RNA product that is specific for a particular organism. In principle, the presence of a specific gene or a particular nucleic acid sequence is interpreted as a definitive identification of the organism. The genotypic approach is highly specific and often very...

Other Immunoassays

Several other methods, including radioimmunoassay (RIA) and fluorescent immunoassay (FIA), are similar to ELISA except that radionudeotides (usually 12SI or ,4C) are substituted for enzymes in RIA and fluoro-chromes are substituted for enzymes in FIA. Although RIA was formerly the key method for antigen detection for numerous infectious agents, including hepatitis B virus, it has been largely replaced by ELISA testing, which does not require use of radioactive substances. An optical immunoassay...

Outcome Of Infectious Diseases

Given the complexities of host defenses and microbial virulence, it is not surprising that the factors determining outcome between these two living entities are also complicated. Basically, outcome depends on the state of the host's health, the virulence of the pathogen, and whether the host can clear the pathogen before infection and disease cause irreparable harm or death (Figure 3-11). The time for a disease or infection to develop also depends on host and microbial factors. Infectious...

Overuse Of Antibiotics

Physical barriers (i.e skin or mucosal surfaces) overcoming these defensive barriers depends on both host and microbial factors. When these barriers are broken, numerous other host defensive strategies are activated. Any situation that disrupts the physical barrier of the skin and mucosa, alters the environmental conditions (e.g., loss of stomach acidity or dryness of skin), changes the functioning of surface cells, or alters the normal flora population can facilitate the penetration of...

Overview Of Molecular Methods

Because molecular diagnostic tests are based on the consistent and somewhat predictable nature of DNA and RNA, understanding these methods requires a basic understanding of nucleic acid composition and structure. Therefore, a review of the section titled, Nucleic Acid Structure and Organization in Chapter 2 may be helpful. The molecular methods to be discussed are classified into one of three categories hybridization, amplification, and sequencing and enzymatic digestion of nucleic acids.

P

Peptone base broth with glucose and mannitol. Sodium citrate and sodium desoxycholate act as inhibitory agents Selective (enrichment) liquid medium for enteric pathogens _ Peptone base agar with bile salts, lactose, sucrose, salicin, and ferric ammonium citrate. Indicators include bromthymol blue and acid fuchsin Differential, selective medium for the isolation and differentiation of Salmonella and Shigella spp. from other gram-negative enteric bacilli PaptonB base with lactose. Gram-positive...

Part V

Chapter 50 Laboratory Methods in Basic Mycology, 629 General Features of the Fungi, 629 Taxonomy of the Fungi, 632 Practical Classification of the Fungi, 634 Virulence Factors of the Medically Important Fungi, 636 General Considerations for the Laboratory Diagnosis of Fungal Infections, 642 Extent of Identification of Fungi Recovered from Clinical Specimens, 645 General Considerations for the Identification of Molds, 653 General Morphologic Features of the Molds, 657 Hyaline, Pauciseptate Molds...

Part

Chapter 52 Bloodstream Infections, 778 General Considerations, 778 Detection of Bacteremia, 784 Special Considerations for Other Relevant Organisms Isolated from Blood, 794 Chapter 53 Infections of the Lower Respiratory Tract, 798 General Considerations, 798 Diseases of the Lower Respiratory Bract, 801 Laboratory Diagnosis of Lower Respiratory Tract Infections, 807 Chapter 54 Upper Respiratory Tract Infections and Other Infections of the Oral Cavity and Neck, 814 Diseases of the Upper...

Part Viii

Chapter 62 Laboratory Physical Design, Space Requirements and Organization of Work Flow, 915 Regulation of the Microbiology Laboratory, 918 Selection of Diagnostic Tests, 921 Cost Accounting, 924 Budgeting, 926 Inventory Control, 926 Interviewing and Hiring Employees, 927 Organization of the Microbiology Laboratory, 928 Design of Laboratory Handbook for Clinical Staff, 929 Design of Laboratory Requisition Form, 929 Design of Laboratory Workcard, 930 Design of Laboratory Report Form, 930 Writing...

Partially Acidfast Aerobic Actinomycetes

Organisms belonging to the genus Nocardia are grampositive (often with a beaded appearance), variably acid-fast, catalase-positive, and strictly aerobic. As they grow, Nocardia spp. form branched filaments that extend along the agar surface, that is, substrate hyphae, and into the air, that is, aerial hyphae. As the organisms age, nocardiae fragment into pleomorphic , rods or coccoid elements.15 Nocardiae also are characterized by the presence of mesodiaminopimelic acid (DAP) and the sugars...

Pathogenesis

Legionella spp. can infect and multiply within some spedes of free-living amoebae (Hartmannella, Acarii thamoeba, and Naegleria spp.), as well as within Tetrahy mena spp., a ciliated protozoa, or within biofUms (we organized microcolonies of bacteria usually endosed ire polymer matrices that are separated by water channdsj that remove wastes and deliver nutrients).6 This ab of legionellae contributes to its survival in the enviroifl ment. In addition, I. pneumophila exists in two wejjj defined,...

Pathogenesis and spectrum of diseases

The clinically relevant members of the Enterobaaeriaceae can be considered as two groups the opportunistic pathogens and the overt pathogens. Salmonella typhi, Shigella spp., and Y. pestis are among the latter and are the causative agents of typhoid fever, dysentery, and the black plague, respectively. Therefore, their discovery in clinical material should always be considered significant. These organisms, as well as other Salmonella spp., produce various potent virulence factors and are...