Carbapenemases and extended-spectrum ß-lactamases producing Enterobacteriaceae isolated from Tunisian and Libyan hospitals.

INTRODUCTION: The aim of the study was to investigate the prevalence of extended-spectrum ß-lactamase (ESBL) and carbapenemase production among clinical isolates of Enterobacteriaceae recovered from Tunisian and Libyan hospitals. METHODOLOGY: Bacterial isolates were recovered from patients in intensive care units and identified by biochemical tests and MALDI-TOF. Antibiotic susceptibility testing was performed by disk diffusion and the E-test method. ESBL and carbapenemase activities were detected using standard microbiological tests. Antibiotic resistance-encoding genes were screened by PCR and sequencing. Clonal relationships between Klebsiella pneumoniae strains were carried out using multi-locus sequence typing (MLST). RESULTS: A total of 87 isolates were characterized, with 51 and 36, respectively, identified as E. coli and K. pneumoniae. Overall the resistance prevalence was high for aminoglycosides (> 60%), fluoroquinolones (> 80%), and extended-spectrum cephalosporins (> 94%), and was low for imipenem (11.4%). Among this collection, 58 strains (66.6%) were ESBL producers and 10 K. pneumoniae strains (11.4%) were carbapenemase producers. The antibiotic resistance-encoding genes detected were blaCTX-M-15 (51.7%), blaTEM-1 (35.6%), several variants of blaSHV (21.8%), and blaOXA-48 (11.4%). The MLST typing of K. pneumoniae isolates revealed the presence of multiple clones and three novel sequence types. Also, close relationships between the OXA-48-producing strains from Tunisia and Libya were demonstrated. CONCLUSIONS: This study is the first paper describing the emergence of carbapenemase- and ESBL-producing Enterobacteriaceae, sensitive to colistin, isolated in Tunisia and Libya. Active surveillance and testing for susceptibility to colistin should be implementing because resistance to colistin, mainly in Klebsiella, has been recently reported worldwide.

Early detection of metallo-ß-lactamase NDM-1- and OXA-23 carbapenemase-producing Acinetobacter baumannii in Libyan hospitals.

Acinetobacter baumannii is an opportunistic pathogen causing various nosocomial infections. The aim of this study was to characterise the molecular support of carbapenem-resistant A. baumannii clinical isolates recovered from two Libyan hospitals. Bacterial isolates were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Antibiotic susceptibility testing was performed using disk diffusion and Etest methods, and carbapenem resistance determinants were studied by PCR amplification and sequencing. Multilocus sequence typing (MLST) was performed for typing of the isolates. All 36 imipenem-resistant isolates tested were identified as A. baumannii. The blaOXA-23 gene was detected in 29 strains (80.6%). The metallo-ß-lactamase blaNDM-1 gene was detected in eight isolates (22.2%), showing dissemination of multidrug-resistant (MDR) A. baumannii in Tripoli Medical Center and Burn and Plastic Surgery Hospital in Libya, including one isolate that co-expressed the blaOXA-23 gene. MLST revealed several sequence types (STs). Imipenem-resistant A. baumannii ST2 was the predominant clone (16/36; 44.4%). This study shows that NDM-1 and OXA-23 contribute to antibiotic resistance in Libyan hospitals and represents the first incidence of the association of these two carbapenemases in an autochthonous MDR A. baumannii isolated from patients in Libya, indicating that there is a longstanding infection control problem in these hospitals.

Emergence of Carbapenem-Resistant Pseudomonas aeruginosa and Acinetobacter baumannii Clinical Isolates Collected from Some Libyan Hospitals.

The aim of the present study was to investigate the molecular mechanism of carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii clinical isolates recovered from Libyan hospitals between April 2013 and April 2014. In total, 49 strains (24 P. aeruginosa and 25 A. baumannii) were isolated, including 21 P. aeruginosa and 22 A. baumannii isolates (87.75%) resistant to imipenem (minimum inhibitory concentrations ≥16 µg/ml). The blaVIM-2 gene was detected in 19 P. aeruginosa isolates. All imipenem-resistant P. aeruginosa isolates showed the presence of OprD mutations. Acquired OXA-carbapenemase-encoding genes were present in all A. baumannii isolates: blaOXA-23 (n=19) and blaOXA-24 (n=3). Finally, a total of 13 and 17 different sequence types were assigned to the 21 P. aeruginosa and the 22 A. baumannii carbapenem-resistant isolates, respectively. This study is the first report describing imipenem-resistant P. aeruginosa and A. baumannii isolated from patients in Libya. We report the first case of co-occurrence of blaVIM-2 with oprD porin loss in identical isolates of P. aeruginosa in Libya and demonstrate that these oprD mutations can be used as a tool to study the clonality in P. aeruginosa isolates. We also report the first identification of multidrug-resistant A. baumannii isolates harboring blaOXA-23-like, blaOXA-24-like, and blaOXA-48-like genes in Libya.