Lysis Centrifugation

The lysis centrifugation system commercially available is the Isolator (Wampole Laboratories, Cranbury, NJ), The

Wampole Tubes

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 medium-containing base bottle is inoculated with blood, and the top piece containing agar paddles is added in the laboratory. The agar is inoculated by tipping the bottle to allow the blood-containing medium to flow over the agar.

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.)

Isolator consists of a stoppered tube containing saponin to lyse blood cells, polypropylene glycol to decrease foaming, SPS as an anticoagulant, EDTA to chelate calcium ions and thus inhibit the complement cascade and coagulation, and a small amount of an inert fluo-rochemical (Fluorinert, 3M Co., St. Paul, Minn) to cushion and concentrate the microorganisms during 30-minute centrifugation at 3000x g (Figure 52-6). After centrifugation, the supernatant is discarded, the sediment containing the pathogen is vigorously vortexed, and the entire sediment is plated to solid agar. Benefits of this system include the more rapid and greater recovery of filamentous fungi, the presence of actual colonies for direct identification and susceptibility testing after initial incubation, the ability to quantify the colony-forming units present in the blood, rapid detection of polymicrobial bacteremia, dispensing with the need for a separate antibiotic-removal step, the ability to choose spedal media for initial culture setup based on clinical impression- (e.g., direct plating onto media supportive of Legionella spp. or Mycobacterium spp.), and possible greater recovery of intracellular microorganisms caused by lysis of host cells. Possible limitations of the system seem to be a relatively high rate of plate contamination and a decreased ability to detect certain bacteria, such as Streptococcus pneumoniae, Listeria monocytogenes, Haemophilus influenzae, and anaerobic bacteria, compared with conventional systems.

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Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

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