Prevalence and characterisation of carbapenemase encoding genes in multidrug-resistant Gram-negative bacilli

Abstract

Background Emerging worldwide in the past decade, there has been a significant increase in multidrug-resistant bacteria from serious nosocomial infections, especially carbapenemase-producing Gram-negative bacilli that have emerged worldwide. The objective of this study is to investigate carbapenem resistance in Gram-negative bacilli bacteria using phenotypic detection, antimicrobial resistance profiles and genotypic characterisation methods. Methods 200 Gram-negative bacilli isolates were collected from different clinical specimens. All clinical samples were exposed to isolation and identification of significant pathogens applying bacteriological examination and an automated Vitek-2 system. The isolates were subjected to susceptibility tests by the Vitek-2 automated system and those isolates that were resistant to beta-lactam drugs, including carbapenems, third-generation cephalosporines or cefoxitin, were selected for phenotyping using Carba plus disc system assay for detection of carbapenemase-producing isolates. These isolates were further confirmed by molecular detection. PCR was used for the detection carbapenem-resistant genes (OXA-48, IMP, NDM, VIM, and KPC). Results 110 (55%) of 200 Gram-negative bacilli were identified as beta-lactam-resistant isolates. The frequency of carbapenem-resistant isolates was calculated to be 30.9% (n = 34/110). A collection totalling 65/110 (59%) isolates were identified as carbapenemase producers by phenotypic method. Moreover, among the 65 carbapenemase-producing Gram-negative isolates with a positive phenotype-based result, 30 (46%), 20 (30%) and 18 (27%) isolates were positive for OXA-48, KPC and MBL enzymes, respectively, as well as the production of 27% of AmpC with porin loss. Tigecycline was the most effective antibiotic that affected 70% of MDR isolates, but high rates of resistance were detected to other tested antimicrobials. Of interest, a high incidence of MDR, XDR and PDR profiles were observed among all carbapenemase-producing isolates. 36% (24/65) of the tested isolates were MDR to 3 to 5 antimicrobial classes. 29% (17/65) of the recovered isolates were XDR to 6 to 7 antimicrobial classes. Alarmingly, 24% (16/65) of isolates displayed PDR to all the tested 8 antimicrobial classes. Genotype assay, including 53 phenotypically confirmed carbapenemase-producing isolates of Gram-negative bacilli, found 51(96%) isolates were harbouring one or more genes. The most common carbapenemase gene was bla NDM 83% (44/53) followed by bla OXA-48 75% (40/53), bla VIM 49% (26/53) and bla IMP 43% (23/53), while the gene bla KPC was least frequent 7% (4/53). 92% (46/51) of isolates were involved in the production of more than one carbapenemase gene. Conclusion This study demonstrated the emergence of carbapenemase-producing Gram-negative pathogens implicated in healthcare-related infections. Accurate identification of carbapenem-resistant bacterial pathogens is essential for patient treatment, as well as the development of appropriate contamination control measures to limit the rapid spread of pathogens. Tigecycline exhibited potent antimicrobial activity against MDR, XDR and PDR-producing strains that establish a threatening alert which indicates the complex therapy of infections caused by these pathogens.

Phenotypic and genotypic detection of carbapenemase production among gram negative bacteria isolated from hospital acquired infections

“…To decrease the threat of infection spreading in the hospital and to reduce mortality rates, this study re-connoitered the existence of carbapenemase-producing organisms using phenotypic methods and determined the distribution of carbapenemase genes by genotypic testing. The prevalence of carbapenem resistance was 17.0% in this study, which is similar to Haji et al 18 ’s study. The incidence of prevalence in various parts of India varies from 14-69%.…”

Molecular Characterisation of Carbapenemase-Producing Acinetobacter baumannii isolates from Hospitalised Patients in Iraq

“…Genes encoding class A carbapenemases, like blaKPC, have also not been found in any of our isolates. These findings were consistent with previous research in Kufa-Iraq (Tuwaij, 2016) and Baghdad (Ghaima, 2018), but disagreed with a study in Erbil (Haji et al, 2021) that recorded KPC in its isolates. This is likely the first report of carbapenemase genes in clinical isolates of A. baumannii in Duhok province, Iraq.…”

Carbapenem-Resistant Gram-Negative Bacilli Causing Ventilator Associated Pneumonia: Study of MASTDISCS Combi Carba Plus for Detection of Carbapenemase Producing Enterobacterales

“…Several studies revealed that K. pneumoniae and A. baumannii harbored more than one gene, making them more likely to be multi-or pan-drug resistant. [49][50][51][52][53] This finding can be challenged due to risk of resistance transmission and restricted antibiotics valuable for…”

“…However, Haji et al reported only two isolates that do not show any genes. 52 The efficacy of MAST-Carba plus in detection of carbapenemase activity was evaluated in relation to PCR results. The highest sensitivity, specificity, positive and negative predictive values was reported for OXA-48 detection (81.8% 92.5%, 75% and 94.9, respectively).…”