Abstract
The aim of this study was to investigate the drug-resistance and the molecular characterization of carbapenemases, ESBL, and aminoglycoside-modifying enzymes among Acinetobacter baumannii clinical isolates in Algerian hospitals. A total of 92 A. baumannii isolates were collected between 2012 and 2016. Antimicrobial susceptibility testings were performed for β-lactams, aminoglycosides, fluoroquinolones, trimethoprim-sulfamethoxazole, rifampicin and colistin. The phenotypic characterization of β-lactamases was investigated. For 30 randomly targeted strains, the carriage of the carbapenemases, ESBL and aminoglycoside-modifying enzymes -encoding genes was determined by PCR. Sequencing was carried out for carbapenemases and ESBL genes. Most of the 92 isolates studied were recovered from hospitalized patients (93.5%) and were mainly from intensive care units (51.1%) and orthopedics (19.6%). The strains were collected primarily from low respiratory tract (33.7%), wounds (23.9%) and urine (16.3%). Multidrug-resistant A. baumannii strains were prevalent (96.7%). High rates of resistance were observed for almost all antibiotics tested (>70%) excluding rifampicin (7.6%) and colistin (5.4%). For the five colistin-resistant strains, MICs ranged between 4 and 128 µg/mL. Positive MBL (83.7%) and ESBL (23.9%) strains were identified. Regarding β-lactams, the blaNDM and both blaSHV and blaCTX-M1 genes were detected in five and two strains respectively. Sequencing of the genes revealed the presence of blaNDM-1, blaCTX-M-15, and blaSHV-33. For aminoglycosides, aac(6')-Ib, ant(2'')-I and aph(3')-VI genes were detected in three, seven and six strains respectively. Here, we report the first co-occurrence of extended-spectrum β-lactamases SHV-33 and CTX-M-15, the carbapenemase NDM-1 and the emergence of colistin-resistant A. baumannii in Algerian hospitals.
Highlights
Acinetobacter baumannii is a Gram-negative opportunistic nosocomial pathogen causing clinical infections and outbreaks in healthcare settings especially in intensive care units (ICUs)
These samples were from intensive care units (ICUs) (51.1%), orthopedics (19.6%), medicine (13.0%), surgery (9.8%) and 6 outpatients (6.5%)
Our findings are moderately higher than the Algerian Antimicrobial Resistance Network (AARN) data recorded in Acinetobacter spp. during the same period [18], and studies carried out in Westen Algeria in 2013 and Algiers in 2015 [19,20]
Summary
Acinetobacter baumannii is a Gram-negative opportunistic nosocomial pathogen causing clinical infections and outbreaks in healthcare settings especially in intensive care units (ICUs). This species account for almost 90% of all reported Acinetobacter infections, including respiratory tract infections, bacteremia, meningitis, wound infections and urinary tract infections [1,2]. The emergence of A. baumannii resistant to carbapenems, a last-line group of β-lactams for treatment of patients infected with multidrug-resistant bacteria, was reported [6,7,8,9]. The World Health Organization recognize carbapenem-resistant A. baumannii (CRAB) as the first critical priority in its list of 12 resistant-bacteria that pose the greatest threat to human health [10]
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