Molecular characteristics and antibiotic resistance of Acinetobacter baumanniibeta-lactamase-producing isolates, a predominance of intrinsic blaOXA-51, and detection of TEM and CTX-M genes

Abstract

The aim of this study was to determine the molecular characteristics and antibiotic resistance of 13 (10 inpatient and three outpatient) Acinetobacter baumannii beta-lactamase-producing isolates collected in Bosnia and Herzegovina between December 2009 and May 2010.Materials and methods: Susceptibility testing was performed by disk diffusion and broth microdilution methods. The modified Hodge and combined disk test with EDTA/phenylboronic acid was used to screen for carbapenemase production. Production of extended spectrum beta-lactamases (ESBLs) was determined by double-disk synergy test. PCR was used to detect blaESBL/blacarb genes.Results: Ten (22.2%) inpatient and three (13.6%) outpatient isolates produced beta-lactamases, ESBLs, or oxacillinases. More than 50% of the isolates showed multidrug resistance. Resistance rates to gentamicin and ciprofloxacin of the inpatients and outpatients were 80.0%, 60.0%, 75.0%, and 25.0%, respectively. MICs of carbapenems for resistant isolates ranged from 32 to >256 µg/mL. All imipenemresistant Acinetobacter baumannii strains contained bla OXA-51 . Three of the 10 inpatient isolates and one outpatient isolate containing bla OXA-51 additionally produced other beta-lactamases (TEM/CTX-M/OXA-1). None of the inpatient or outpatient isolates were positive for other carbapenemases, especially acquired oxacillinases (bla OXA-23 /bla OXA-24 /bla OXA-58 /bla OXA-143 ). Conclusion: Production of bla OXA-51 presents an emerging threat in imipenem-resistant Acinetobacter spp. from Bosnia and Herzegovina.

Arrival of carbapenem-hydrolyzing-oxacillinases in Acinetobacter baumannii in Bosnia and Herzegovina

“…ISAba1 (Ibrahimagić et al, 2017). In this study a shift to CHDL was observed Sequencing of blaOXA-40 gene revealed the OXA-72 allelic variant associated with high level of resistance to carbapenems.…”

“…This prompted us to analyze these isolates with regards to genetic diversity, antibiotic susceptibility and occurrence of acquired carbapenem resistance genes. The previous studies from 2009 found that reduced susceptibility in A. baumannii from Bosnia was solely atributed to overexpression of intrinsic OXA-51 β-lactamase with ISAba1 upstream of the gene (Ibrahimagić et al, 2017). The new isolates were collected during two periods: in 2011 and 2015 and compared to determine the dynamic changes in carbapenemase resistance mechanisms and the population structure.…”

Study of the Gene Expression of aacC1 Gene in Acinetobacter baumannii that Responsible for Aminoglycoside Resistance

“…The current study showed that A. baumannii resistance to Ampicillin, , Ceftazedime , Cifepim, Imipinem and this resistance was due to the possession of (β -lactam) and this bacteria production β-lactamase [16] . β-Lactam ring, which leads to inactivation of the antibiotic.…”

Prevalence of Carbapenemases in Carbapenem-Resistant Acinetobacter baumannii Isolates from the Kingdom of Bahrain

“…The bla OXA-51 is generally found in all A. baumannii isolates, being either carbapenemresistant or carbapenem-sensitive isolates [19][20][21]. This gene is not associated with resistance unless insertion sequences (ISAbaI) upstream of bla OXA-51 are involved, causing over-expression leading to carbapenem resistance, especially to imipenem [21,22]. Therefore, it is recommended as an excellent marker for species identification but not as a resistance marker [22][23][24][25].…”

“…On the other hand, bla OXA-23 is a significant cause of carbapenem resistance in A. baumannii [19,21,22]. It has been reported as a prevalent gene in various studies published in several countries, including Saudi Arabia and Iran [19,21].…”