Characterization of carbapenemase-producing Gram-negative bacilli: first report of blaNDM-1 in Enterobacter cloacae.

INTRODUCTION: The spread of multidrug-resistant bacteria, particularly carbapenem-resistant Gram-negative bacilli (CR-GNB), has become a serious challenge for clinicians due to limited therapeutic options. The aim of the study was to investigate the prevalence of carbapenemase production among clinical isolates recovered from 352 samples collected in Tebessa hospital, Algeria. METHODOLOGY: Bacterial isolates were identified by 16S RNA gene sequencing and susceptibility to antibiotics was determined by disk diffusion method. Carbapenem-resistant isolates were screened for carbapenemase production using modified carba Nordmann-Poirel test, modified Hodge test and imipenem-EDTA combined disc test. Extended-spectrum ß-lactamases (ESBL) were detected using double-disk synergy test. Molecular characterization of carbapenemases and ESBL genes was performed by polymerase chain reaction (PCR) and sequencing. RESULTS: A total of 85 Gram-negative bacilli isolates were recovered mainly from urine samples and were identified as: Klebsiella pneumoniae (17.65%), Serratia odorifera (15.29%), Escherichia coli (12.94%), Raoultella ornithinolytica, Enterobacter cloacae (11.76%), Serratia marcescens (10.59%), Morganella morganii (7.06%), Proteus mirabilis (5.88%), Acinetobacter baumannii (4.70%) and Pseudomonas aeruginosa (2.35%). All strains were resistant or intermediate to imipenem and/or ertapenem. ESBL, carbapenemase and metallo-beta-lactamases (MBL) phenotypes were detected in 19 (22.35%), 9 (10.59%) and 2 (2.35%) GNB isolates, respectively. PCR results in nine carbapenemase-producing GNB strains chosen showed the presence of one to four carbapenemase genes (blaGES, blaSME, blaNDM-1, blaVIM, blaGIM, blaSPM, blaOXA-48) in four strains; however, seven strains had at least one ESBL gene (blaTEM-1, blaCTXM-15, blaSHV). CONCLUSIONS: In this study, we report the first incidence of blaNDM-1 gene in Enterobacter cloacae isolated from urine sample in Algeria.

External Bacterial Flora and Antimicrobial Susceptibility Patterns of Staphylococcus spp. and Pseudomonas spp. Isolated from Two Household Cockroaches, Blattella germanica and Blatta orientalis.

A study was performed to estimate the prevalence of the external bacterial flora of two domestic cockroaches (Blattella germanica and Blatta orientalis) collected from households in Tebessa (northeast Algeria). Three major bacterial groups were cultured (total aerobic, enterobacteria, and staphylococci) from 14 specimens of cockroaches, and antibiotic susceptibility was tested for both Staphylococcus and Pseudomonas isolates. Culturing showed that the total bacterial load of cockroaches from different households were comparable (P<0.001) and enterobacteria were the predominant colonizers of the insect surface, with a bacterial load of (2.1 × 105 CFU/insect), whereas the staphylococci group was the minority. Twenty-eight bacterial species were isolated, and susceptibility patterns showed that most of the staphylococci isolates were highly susceptible to chloramphenicol, gentamycin, pristinamycin, ofloxacin, clindamycin, and vancomycin; however, Pseudomonas strains exhibited resistance to amoxicillin/clavulanic acid, imipenem, and the second-generation antibiotic cephalosporin cefuroxime.