Role of Beta LactamaseProducing Bacteria

Bacterial resistance to the antibiotics used for the treatment of sinusitis has consistently increased in recent years. Production of the enzyme beta-lactamase is one of the most important mechanisms of penicillin resistance. Several potential aerobic and anaerobic BLPB occur in sinusitis.

BLPB have been recovered from over a third of patients with acute and chronic sinusitis (8-11,18). H. influenzae and M. caterrhalis are the predominate BLPB in acute sinusitis (18) and S. aureus, pigmented Prevotella and Porphyromonas spp. and Fusobacterium spp., predominate in chronic sinusitis (8-11).

Most Prevotella and Fusobacterium spp. strains were considered susceptible to penicillin. However, within the past two decades, penicillin-resistant strains have been reported with increasing frequency (70). These species are the predominant AGNB in the oral flora and are most commonly recovered in anaerobic infections in and around the oral cavity (33).

BLPB may shield penicillin-susceptible organisms from the activity of penicillin, thereby contributing to their persistence. The ability of BLPB to protect penicillin-sensitive microorganisms has been demonstrated in vitro and in vivo (71).

The actual activity of the enzyme beta-lactamase and the phenomenon of "shielding" were demonstrated in acutely and chronically inflamed sinuses fluids (72). BLPB were isolated in 4 of 10 acute sinusitis (Table 5) and in 10 of 13 chronic sinusitis aspirates. The predominate BLPB isolated in acute sinusitis were H. influenzae and M. catarrhalis, and those found in chronic sinusitis were Prevotella and Fusobacterium spp. The recovery of BLPB is not surprising, since over two-thirds of the patients with acute and all of the patients with chronic sinusitis received antimicrobial agents that might have selected for BLPB. These data suggest that therapy should be directed at the eradication of BLPB whenever present.

TABLE 5 Beta-Lactamase Detected in Chronic Sinusitis Aspirates

Patient No.

TABLE 5 Beta-Lactamase Detected in Chronic Sinusitis Aspirates

Patient No.

Organism

1

2

3

4

Staphylococcus aureus (BL +)

+

+

Streptococcus pneumoniae

+

Peptostreptococcus spp.

+

+

Propionibacterium acnes

+

Fusobacterium spp. (BL +)

+

+

Fusobacterium spp. (BL -)

+

+

Prevotella spp. (BL +)

+

Prevotella spp. (BL -)

+

+

+

Bacteroides fragilis group (BL +)

+

+

Beta-lactamase activity in pus

+

+

+

+

Abbreviations: BL+, Beta-lactamase-producing bacteria; BL—, Non-beta-lactamase-producing bacteria. Source: From Ref. 71.

0 0

Post a comment