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[Extended spectrum beta-lactamases]
A Philippon1, G Arlet, P Lagrange
1Hôpital Saint-Louis, service de bactériologie-virologie hygiène, Paris.
Abstract:
At least 30 extended-spectrum beta-lactamases (ESB) have emerged responsible for resistance to indigestible beta-lactams (C3G) since their discovery in West Germany in 1983. Most of them are produced by enterobacteria and essentially K. pneumoniae which appeared susceptible to oxyimino-beta-lactams. A double-disk test was useful to detect such nosocomial isolates of enterobacteria (urines, blood, wound, sputum cultures) mostly recovered from patients in intensive care units. These have spread through hospital and outbreaks were described. Because plasmid-encoded this resistance mechanism was spreading among enterobacteria with other resistance markers (e.g. netilmicin, amikacin). It seems highly likely that the use of newer antibiotics favors the appearance of ESB obtained by selection of mutated genes coding for penicillinases (TEM, SHV). Treatment including a beta-lactam is still possible because of the stability of some beta-lactams e.g. cefamycins, carbapenems and the sensitivity to beta-lactam inhibitors. Digestive selective decontamination may overcome outbreak.
Insights
Extended-spectrum beta-lactamases (ESBL) cause resistance to third-generation cephalosporins (C3G) in enterobacteria like K. pneumoniae. Early detection and selective decontamination are key to managing these hospital-acquired infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Context:
- Over 30 extended-spectrum beta-lactamases (ESBL) have emerged since 1983, conferring resistance to third-generation cephalosporins (C3G).
- Enterobacteria, particularly Klebsiella pneumoniae, are primary producers of ESBLs, often exhibiting susceptibility to oxyimino-beta-lactams.
- These resistant strains are frequently isolated from intensive care unit (ICU) patients, leading to hospital-wide spread and outbreaks.
Purpose:
- To highlight the emergence and spread of ESBL-producing enterobacteria.
- To emphasize the utility of a double-disk test for detecting these nosocomial isolates.
- To discuss the implications of antibiotic use on ESBL selection and potential control strategies.
Summary:
- Extended-spectrum beta-lactamases (ESBL) confer resistance to C3G antibiotics in enterobacteria, notably Klebsiella pneumoniae.
- A double-disk test aids in identifying ESBL-producing nosocomial isolates from clinical samples (urine, blood, wound, sputum).
- Plasmid-encoded ESBL resistance spreads among enterobacteria, often alongside other antibiotic resistance markers, and may be driven by the use of newer antibiotics.
Impact:
- Effective detection methods like the double-disk test are crucial for managing hospital-acquired infections caused by ESBL producers.
- Understanding the plasmid-mediated spread of resistance informs infection control strategies.
- While resistance is a concern, treatments with cefamycins, carbapenems, and beta-lactam inhibitors remain viable options.
- Digestive selective decontamination shows promise in controlling ESBL outbreaks.