Related Experiment Videos
The occurrence, virulence, and antimicrobial resistance of anaerobes in polymicrobial infections
1Department of Medicine, Louisiana State University Medical Center, New Orleans 70112, USA.
Abstract:
Polymicrobial aerobic/anaerobic bacterial infections occur frequently and have been documented in most anatomic sites in the body. The etiology of these infections is endogenous in that the normal microbial flora that colonize the various mucosal surfaces of the body can be isolated from these infections after trauma to these membranes allowing these organisms access to normally sterile sites. Subsequently, the organisms begin to proliferate, causing extensive tissue damage. These infections may spread to adjacent tissues or become loculated with abscess formation. In patients judged to have severe infection, surgery is often needed to debride the advancing spread of the infection, remove loculated pus, and reestablish sufficient blood flow to deliver appropriate antimicrobial agents to the infected site. Choice of antimicrobial agents should include agents with activity against both aerobes and anaerobes. Although a variety of anaerobes can be isolated from these infections, the Bacteroides fragilis group is the most clinically important group of anaerobes because of the production of virulence factors and the high incidence of beta-lactamase production. Against the various B. fragilis group species, metronidazole remains a very active agent, whereas resistance rates to clindamycin are high among the non-B. fragilis species. Because of the good activity of many cephalosporin/cephamycin agents against aerobic gram-negative bacteria and moderate to good activity against anaerobes, these compounds remain as broad-spectrum choices for use in therapy of mixed infections. The addition of beta-lactamase inhibitors (tazobactam, sulbactam, or clavulanate) to various beta-lactam agents has increased their antimicrobial spectrum against certain groups of aerobes, and particularly against beta-lactamase-producing anaerobes, including the B. fragilis group. The choice of single-agent therapy of mixed infections is ideally based on local data of susceptibility patterns of the various aerobes and anaerobes involved in these infections.
Insights
Polymicrobial aerobic and anaerobic bacterial infections are common and often endogenous. Effective treatment requires antimicrobial agents targeting both bacteria, with careful consideration of resistance patterns for optimal outcomes.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Polymicrobial aerobic/anaerobic bacterial infections frequently occur from endogenous flora accessing sterile sites via trauma.
- These infections can lead to extensive tissue damage, spread, and abscess formation, often necessitating surgical intervention.
- Severe infections require surgical debridement and restoration of blood flow for effective antimicrobial delivery.
Purpose of the Study:
- To review the characteristics and treatment strategies for polymicrobial aerobic/anaerobic bacterial infections.
- To highlight the importance of selecting antimicrobial agents with broad-spectrum activity against both aerobic and anaerobic pathogens.
- To discuss the role of specific antimicrobial agents and combinations in managing these complex infections.
Main Methods:
- Review of literature on polymicrobial infections, focusing on etiology, pathogenesis, and treatment.
- Analysis of antimicrobial susceptibility data for common aerobic and anaerobic bacteria, including the Bacteroides fragilis group.
- Evaluation of the efficacy of various antimicrobial classes, such as metronidazole, cephalosporins, and beta-lactamase inhibitor combinations.
Main Results:
- The Bacteroides fragilis group is a clinically significant anaerobe due to virulence factors and beta-lactamase production.
- Metronidazole shows consistent activity against B. fragilis group species, while clindamycin resistance is high in non-B. fragilis species.
- Cephalosporins/cephamycins offer broad-spectrum coverage, and beta-lactamase inhibitors enhance activity against resistant anaerobes.
Conclusions:
- Treatment of polymicrobial infections necessitates agents active against both aerobes and anaerobes.
- Antimicrobial selection should consider local susceptibility data, particularly for beta-lactamase-producing anaerobes.
- Combination therapies and agents with beta-lactamase inhibitors are valuable for managing mixed aerobic/anaerobic infections.