Detection of carbapenemases, AmpC and ESBL genes in Acinetobacter isolates from ICUs by DNA microarray

Abstract

The accumulation of multiple inherent and acquired resistance mechanisms in Acinetobacter sp. results in emergence of "pandrug resistant" strains which is one of the major concerns in healthcare sectors worldwide. Surveillance of the carbapenemase/ extended-spectrum β-lactamases (ESBLs) genes in A. baumannnii by phenotypic methods is challenging especially in developing countries, like Pakistan. In this context, a novel microarray (CT 103XL Check-MDR) assay was used for simultaneous detection of genes encoding clinically important carbapenemases and ESBLs. The results were compared with the phenotypic methods including MHT, Rapidec Carba NP, EDTA+DDST and Rosco (KPC/MBL). The results of the microarray were also confirmed by PCR. All of the strains of A. baumannii (47) were resistant to imipenem and meropenem, while the other species of Acinetobacter were sensitive. Microarray and PCR results showed presence of OXA-23 in all the isolates of A. baumannii while 36.17% also harbored PER. Rosco kit test showed 100% sensitivity to detect carbapenemases but exhibited low specificity to classify them. Rapidec Carba NP test has 100% sensitivity and specificity to detect the carbapenemases when compared with microarray. Sensitivity and specificity of microarray assay were 100% for bla-genes in comparison to PCR. This reveals that Check-MDR CT103 XL assay is an accurate method for the identification of ESBLs and carbapenemase genes in A. baumannii in comparison to the other methods.

Study of genetic diversity, biofilm formation, and detection of Carbapenemase, MBL, ESBL, and tetracycline resistance genes in multidrug-resistant Acinetobacter baumannii isolated from burn wound infections in Iran

“…bla OXA-23-like and bla OXA-40-like are common in CNSAB isolates. Similar to other studies carried out in Iran, bla OXA-23-like was the most prevalent OXA-type carbapenemases among carbapenem-resistant strains, [6] and it has reported frequently in many countries including Pakistan, South Korea, and China [26]. According to the data represented in Table 5, increased MIC values observed for imipenem and meropenem in studied bla OXA-23-like and bla OXA-40-like carrying isolates.…”

“…In addition, the results obtained by phenotypic identification of MBL production did not comply with genotypic results and indicating that false-positive results among these strains with respect to resistance phenotype. This phenomenon may appear due to effect of the EDTA on cell wall of A. baumannii or as chelator to inhibit OXA enzymes [26, 34].…”

Occurrence of blaTEM and blaCTXM Genes and Biofilm-Forming Ability among Clinical Isolates of Pseudomonas aeruginosa and Acinetobacter baumannii in Yaoundé, Cameroon

“…It can be deduced that combinatorial effects of antibiotics may be beneficial in treating nosocomial infections caused by either PSA or ACB. This observation corroborates with previous reports by Litake et al [60] and Uddin et al [61]. In order to treat infections caused by bacteria, antibiotics can be used either singly or in combination.…”

“…Our findings contradict those of Gupta et al [56] who obtained MBLs among 10% of the PSA isolates. Their finding as well as ours were lower than other reports previously documented in India and Pakistan in which 29% and 12% of PSA and ACB, respectively, were positive for MBL phenotypes [56,61]. In this study, large proportions (80% to 100%) of the isolates that expressed either AmpC, ESBLs or MBLs phenotypes were also MDR.…”

Insights into Acinetobacter baumannii: A Review of Microbiological, Virulence, and Resistance Traits in a Threatening Nosocomial Pathogen

“…They hydrolyze all penicillins and cephalosporins with the exception of cephamycins [128]. CTX-M, GES, PER, SCO, SHV, TEM, and VEB are among identified class A β-lactamases in A. baumannii [129][130][131][132]. While some of these, like SCO-1 and TEM-1, are narrow-spectrum, others like CARB-10, CTX-M-2, CTX-M-15, GES-14, PER-1, PER-7, and SHV-5 are extended spectrum β-lactamases (ESBLs) [133,134].…”