Detection of bla NDM-1 Encoding Imepenemase among the Imipenem-Resistant Gram-Negative Bacilli Isolated from Various Clinical Samples at a Tertiary Care Hospital of Eastern Nepal: A Descriptive Cross-Sectional Study

Detection of blaNDM-1,mcr-1 and MexB in multidrug resistant Pseudomonas aeruginosa isolated from clinical specimens in a tertiary care hospital of Nepal

INTRODUCTION

Pseudomonas aeruginosa is an opportunistic pathogen, which causes healthcare-associated infections in immunosuppressed patients. They exhibit resistance to multiple classes of antibiotics via various mechanisms such as the over-expression of efflux pumps, decreased production of the outer membrane protein (D2 porin), over-expression of the chromosomally encoded AmpC cephalosporinase, modification of drugs, and mutation(s) at the target site of the drug. The bacteria also develop antibiotic resistance through the acquisition of resistance genes carried on mobile genetic elements. Limited data on phenotypic as well as genotypic characterization of MDR P. aeruginosa in Nepal infers the needs for this study. This study was carried out to determine the prevalence rate of metallo-β-lactamase (MBL-producer) as well as colistin resistant multidrug resistant (MDR) P. aeruginosa in Nepal and also to detect MBL, colistin resistance, and efflux pump encoding genes i.e. bla_NDM-1, mcr-1 and MexB respectively in MDR P. aeruginosa isolated from clinical samples.

METHODS/METHODOLOGY

A total of 36 clinical isolates of P. aeruginosa were collected. All bacterial isolates were phenotypically screened for antibiotic susceptibility using Kirby Bauer Disc Diffusion method. All the multidrug resistant P. aeruginosa were phenotypically screened for MBL producer by Imipenem-EDTA combined disc diffusion test (CDDT). Similarly, MIC value for colistin was also determined by broth microdilution method. Genes encoding carbapenemase (bla_NDM-1), colistin resistant (mcr-1) and efflux pump activity (MexB) were assayed by PCR.

RESULTS

Among 36 P. aeruginosa, 50% were found to be MDR among which 66.7% were found to be MBL producer and 11.2% were found to be colistin resistant. Among MDR P. aeruginosa, 16.7%, 11.2% and 94.4% were found to be harbouring bla_NDM-1, mcr-1 and MexB genes respectively.

CONCLUSION

In our study, carbapenemase production (encoded by bla_NDM-1), colistin resistant enzyme production (encoded by mcr-1), and expression of efflux pump (encoded by MexB) are found to be one of the major causes of antibiotic resistance in P. aeruginosa. Therefore, periodic phenotypic as well as genotypic study in Nepal on P. aeruginosa would provide the scenario of resistance pattern or mechanisms in P. aeruginosa. Furthermore, new policies or rules can be implemented in order to control the P. aeruginosa infections.

High prevalence of Panton-Valentine Leucocidin (PVL) toxin carrying MRSA and multidrug resistant gram negative bacteria in late onset neonatal sepsis indicate nosocomial spread in a Pakistani tertiary care hospital

BACKGROUND

Neonatal sepsis has high incidence with significant mortality and morbidity rates in Pakistan. We investigated common etiological patterns of neonatal sepsis at a tertiary care setup.

METHODS

90 pus and blood, gram negative and gram positive bacterial isolates were analyzed for virulence and antibiotic resistance gene profiling using PCR and disc diffusion methods.

RESULTS

Staphylococcus aureus showed strong association with neonatal sepsis (43 %) followed by Citrobacter freundii (21 %), Pseudomonas aeruginosa (13 %), Escherichia coli (15 %) and Salmonella enterica (8 %). Molecular typing of E. coli isolates depicted high prevalence of the virulent F and B2 phylogroups, with 4 hypervirulent phylogroup G isolates. 76.9 % S. aureus isolates showed presence of Luk-PV, encoding for Panton-valentine leucocidin (PVL) toxin with majority also carrying MecA gene and classified as methicillin resistant S. aureus (MRSA). ecpA, papC, fimH and traT virulence genes were detected in E. coli and Salmonella isolates. 47 % Citrobacter freundii isolates carried the shiga like toxin SltII B. Antimicrobial resistance profiling depicted common resistance to cephalosporins, beta lactams and fluoroquinolones.

CONCLUSION

Presence of PVL carrying MRSA and multidrug resistant gram negative bacteria, all isolated from late onset sepsis neonates indicate a predominant nosocomial transmission pattern which may complicate management of the disease in NICU setups.

Phenotypic and genotypic detection of resistance mechanisms in carbapenem-resistant gram-negative bacteria isolated from Egyptian ICU patients with first emergence of NDM-1 producing Klebsiella oxytoca

Background and Objectives

Carbapenems are considered the last resort to treat several infections, particularly in intensive care units (ICUs). However, increasing carbapenem resistance is problematic because it leads to high morbidity and mortality rates. This study aimed to determine the rate of carbapenem resistance among Gram-negative bacteria collected from patients in ICUs and to identify their resistance mechanisms using phenotypic and genotypic methods.

Materials and Methods

Antimicrobial susceptibility testing was carried out using the disc diffusion method among 180 Gram-negative bacterial isolates. Productions of carbapenemases, metallo-beta-lactamases (MBLs) and the harboring of carbapenemase-encoding genes, were detected in 40 selected carbapenem-resistant Gram-negative bacteria (CR-GNB).

Results

Of 40 selected CR-GNB isolates, 28 (70%), and 20 (50%) isolates were phenotypically positive for carbapenemase, and MBL production, respectively. Furthermore, 22 (55%) showed amplification of one or more of the carbapenemase-encoding genes, including bla _NDM-1, bla _VIM-2, and bla _OXA-48. This study described the first emergence of NDM-1 producing Klebsiella oxytoca in Egyptian ICUs.

Conclusion

High incidence of CR-GNB detected in the ICUs in our study area may be attributed to the overuse of antibiotics, including carbapenems, and improper application of infection control measures. These findings confirm the need for the application of a strict antibiotic stewardship program.

Prevalence of carbapenemase-producing Klebsiella pneumoniae at a tertiary care hospital in Kathmandu, Nepal

Aim

Although carbapenem is the last-resort drug for treating drug-resistant Gram-negative bacterial infections, prevalence of carbapenem-resistant bacteria has substantially increased worldwide owing to irrational use of antibiotics particularly in developing countries like Nepal.  Therefore, this study was aimed to determine the prevalence of carbapenemase-producing K. pneumoniae and to detect the carbapenemase genes (blaNDM-2 and blaOXA-48) in at a tertiary care hospital in Nepal.

Materials and methods

A hospital-based cross-sectional study was carried out from June 2018 to January 2019 at the Microbiology Laboratory of Annapurna Neurological Institute and Allied Sciences, Kathmandu, Nepal. Different clinical samples were collected and cultured in appropriate growth media. Biochemical tests were performed for the identification of K. pneumoniae. Antibiotic susceptibility testing (AST) was performed by the Kirby–Bauer disc diffusion method. The modified Hodge test (MHT) was performed to detect carbapenemase producers. The plasmid was extracted by the modified alkaline hydrolysis method. Carbapenemase-producing K. pneumoniae were further confirmed by detecting blaNDM-2 and blaOXA-48 genes by PCR using specific forward and reverse primers followed by gel electrophoresis.

Results

Out of the total 720 samples, 38.9% (280/720) were culture positive. K. pneumoniae was the most predominant isolate 31.4% (88/280). Of 88 K. pneumoniae isolates, 56.8% (50/88) were multi-drug resistant (MDR), and 51.1% (45/88) were MHT positive. Colistin showed the highest sensitivity (100%; 88/88), followed by tigecycline (86.4%; 76/88). blaNDM-2 and blaOXA-48 genes were detected in 24.4% (11/45) and 15.5% (7/45) of carbapenemase-producing K. pneumoniae isolates, respectively.

Conclusion

The rate of MDR and carbapenemase production was high in the K. pneumoniae isolates. Colistin and tigecycline could be the drug of choice for the empirical treatments of MDR and carbapenemase-producing K. pneumoniae. Our study provides a better understanding of antibiotic resistance threat and enables physicians to select the most appropriate antibiotics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41182-021-00368-2.