Molecular characterization of carbapenem-resistant Gram-negative bacilli clinical isolates in Algeria.

OBJECTIVES: The aims of this study were to investigate the occurrence of carbapenem-resistant Gram-negative bacilli (GNB) isolated from inpatients and outpatients in Algeria between July and September 2015, and to screen their resistance mechanisms and genetic relatedness. MATERIALS AND METHODS: A total of 68 non-redundant isolates were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) antibiotic susceptibility testing was performed using disk diffusion and Etest methods. Carbapenemase activity was carried out using modified Carba NP test, EDTA assay, and the modified Hodge test. Molecular characterization of carbapenemases and extended-spectrum ß-lactamase (ESBL) genes were detected by standard PCR and sequencing. Genotyping of carbapenem-resistant isolates was performed by multilocus sequence typing (MLST) analysis. RESULTS: Of the 68 GNB isolates, 13 (19%) showed reduced susceptibility to carbapenems, including, four Klebsiella pneumoniae, one Escherichia coli, six Acinetobacter baumannii, and two Pseudomonas aeruginosa. blaOXA-48 gene was detected in the five Enterobacteriaceae isolates, and blaOXA-23 was identified in all A. baumannii isolates. OprD mutations were revealed in the two P. aeruginosa isolates. A total of 11 out of the 13 carbapenem-resistant GNB were detected in inpatients, and the two remaining strains were isolated from outpatients. Molecular typing showed the presence of four sequence types (STs) among the OXA-48-producing K. pneumoniae isolates: ST101, ST147, ST163, and ST2017. ST533 was identified for the OXA-48 producing E. coli isolate. All of the A. baumannii and P. aeruginosa were assigned to the international clonal lineages ST2 and ST654, respectively. CONCLUSION: This study reports the first detection of the epidemic multidrug-resistant lineage, K. pneumoniae ST147 coproduced blaOXA-48 and ESBL genes in Algeria and represents the first description of OXA-48-producing E. coli ST533 and K. pneumoniae ST163 and ST2017. In addition, this study describes for the first time the emergence of OXA-48-producing E. coli and K. pneumoniae in the community in Algeria, leading to major problems for managing microbial infections.

Characterization of Staphylococcus aureus Isolated from Food Products in Western Algeria.

The current study aimed to characterize Staphylococcus aureus isolates from foodstuffs collected from western Algeria. A total of 153 S. aureus isolates from various raw and processed foods were obtained and identified using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry. Isolates were characterized by antimicrobial susceptibility testing and toxin gene detection. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were identified by detection of the mecA gene and characterized by staphylococcal cassette chromosome mec (SCCmec) typing. We found that 30.9% (153/495) of food samples were contaminated with S. aureus. Thirty-three (21.5%) S. aureus isolates were identified as MRSA, and 16.9% (26/153) carried the mecA gene. Three SCCmec types were identified of which type IV was the most common (69.2%) followed by type V (15.3%) and type II (7.6%). Two MRSA isolates were not typable with SCCmec typing. None of the examined isolates harbored mecC. Furthermore, 14.3% (22/153) of the isolates were toxigenic S. aureus. The cytotoxin gene pvl was detected in 11.1% of the S. aureus isolates. This gene was more commonly detected (76.4%) in MRSA isolates than in methicillin-suceptible Staphylococcus aureus (MSSA) isolates. The tsst-1 gene coding for toxic shock syndrome toxin was isolated rarely (3.2%) and only in MSSA isolates. According to disk diffusion test results, 70 isolates were resistant to only one antimicrobial drug, and 51 (33.3%) isolates were multidrug resistant. Other 32 isolates were susceptible to all antibiotics. Our study highlights, for the first time, a high prevalence of multidrug-resistant S. aureus isolates carrying pvl or tsst-1 found in food products in Algeria. The risk of MRSA transmission through the food chain cannot be disregarded, particularly in uncooked foods.

Identification of vancomycin-susceptible major clones of clinical Enterococcus from Algeria.

The main objectives of this study were to characterize clinical strains of Enterococcus spp. isolated from Algerian inpatients and outpatients, to investigate their susceptibility to antibiotics and to analyse their phylogenetic relatedness. A total of 85 non-duplicate Enterococcus spp. isolates collected between 2010 and 2013 from various clinical samples, including urine, vaginal swab, pus, blood and semen, from Algerian inpatients (n=62) and outpatients (n=23) were identified using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS). Antibiotic susceptibility testing was performed using disk diffusion and Etest methods. Clonal relatedness was analysed using multilocus sequence typing (MLST). Enterococcus faecalis was the most predominant species (75.3%), followed by Enterococcus faecium (21.2%), Enterococcus gallinarum (2.4%) and Enterococcus casseliflavus (1.2%). High-level resistance to aminoglycosides was significantly more prevalent in hospitalized patients than in outpatients. None of the E. faecalis and E. faecium isolates were resistant to vancomycin. High genetic diversity was observed among the E. faecalis isolates, with the identification of a new clonal complex (CC256), as well as the detection of E. faecalis ST6 and E. faecium lineages ST17, ST18 and ST78 associated with hospital isolates. This is the first report of E. faecalis ST6 and E. faecium ST17 and ST18 in Algeria. Although acquired vancomycin resistance was not observed among the enterococcal strains, there is a continued need to monitor the level of antibiotic resistance among enterococci as well as the evolution of the E. faecalis/E. faecium ratio.