Phenotypic and Molecular Detection of BlaNDM Gene Among Drug-Resistant Klebsiella Isolates.

BACKGROUND: In the past few centuries, a widespread increase in antimicrobial resistance has been observed among Klebsiella species. The antibiotic- resistant strains of the genus Klebsiella are becoming a serious threat in clinical settings due to their involvement in severe invasive and non-invasive infections. The emergence of resistance among these strains is associated with their strong enzymatic activity against several broad-spectrum antibiotics. These enzymes include beta-lactamases, extended-spectrum beta-lactamases (ESBL), AmpC beta-lactamases, and carbapenemases. These resistance enzymes are capable of hydrolyzing various broad-spectrum drugs like extended-spectrum cephalosporin and carbapenems. OBJECTIVE: The present study was conducted to determine the emerging resistance among Klebsiella strains by identifying the production of carbapenemase enzyme phenotypically and the frequency of the NDM resistance gene by a polymerase chain reaction. METHODS: In this study, 236 Gram-negative isolates from different clinical laboratories were identified. Out of which, 125 isolates were found as Klebsiella species by using standard microbiological techniques. Minimum inhibitory concentrations (MIC) were determined using eight representative antibiotics by the Macro broth dilution method. Phenotypic detection of carbapenemase producing Klebsiella species was performed by Modified Hodge Test. Phenotypic findings were then checked and compared with genotypic results obtained by using the Polymerase chain reaction (PCR) for the detection of resistance genes responsible for the production of carbapenemase. RESULTS: In this study, carbapenemase production was found only in 6 (5%) Klebsiella isolates by using the phenotypic method; however, 3 isolates out of 125 were screened positive for the gene NDM-1. CONCLUSION: Since we are considering carbapenems as the last therapeutic option for treating infections, mainly caused by Gram-negative isolates, the prevailing resistance against this drug is widely disseminating. It is better to evaluate the antibiotic susceptibility, phenotypic screening as well genotypic screening (where possible) for implementing strict antibiotic control policies in health care settings, hospitals, laboratories, etc.

An Overview of Immune Evasion Strategies of DNA and RNA Viruses.

A successful viral infection is due to the effective evasion of viruses of the immune system. The entry of viruses is usually detected by different cellular receptors including PRRs. Recognition of the viral genome leads to the production of interferons through a signaling stream. This review article provides brief information regarding escape mechanisms of DNA and RNA viruses from the host immune system. These strategies include viral endonuclease activity, cap snatching of host mRNA, the formation of replication organelles, stress granule formation, membrane modifications, action of proteases, and evasion from ISGs. Moreover, the strategies of DNA viruses to inhibit immune responses include subversion of mRNA, transcriptional factors, adaptor proteins, PRRs, evasion from T lymphocytes, genomic diversity, theft or seizure of host defense proteins, imitation of host factors like affecting cytokines and chemokines of the host, suppression or inhibition of apoptosis, and proteasomal degradation of host antiviral proteins by DNA viruses. The knowledge of these mechanisms is pivotal to understanding different methodologies that viruses have created to escape antiviral cellular reactions of the host as well as virus-host interactions and the origin of viral pathogenesis. Also, this knowledge is significant for the design of gene targeting vectors, antiviral vaccines, and the development of effective treatments directed against DNA and RNA viruses.

Molecular Detection of TEM, SHV and CTX-M Genes Among Gram-negative Klebsiella Isolates.

INTRODUCTION: In the past few years, the use of antimicrobial drugs against a wide range of pathogens has increased significantly. This extensive use of drugs has increased the resistance rate in microbial community widely. Molecular techniques for the detection of resistance are more reliable as compared to the conventional phenotypic method. BACKGROUND: The family Enterobacteriaceae is considered to be an important cause of nosocomial infections due to its predominantly active species such as E. coli, Klebsiella and Pseudomonas. These organisms are mainly involved in causing pneumonia, sepsis, post-surgical and urinary tract infections. Resistance against antimicrobial drugs among these isolates is increasing more rapidly all over the world. This study primarily focuses on the resistant isolates of Klebsiella species. The drug resistance in Klebsiella isolates is found to be associated with the production of resistance enzymes such as beta lactamase and extended spectrum beta lactamase (ESBLs) which confer resistance, most specifically against cephalosporins and extended spectrum cephalosporins. Since these enzymes are plasmid mediated, they can also produce resistance against several other antimicrobials. It has been found that among the genus Klebsiella, ESBLs are more prevalent in K. pneumoniae followed by K. oxytoca. METHODS: In this study, we estimated the distribution of ESBL producers among Klebsiella species and performed their genetic characterization. A total of 236 gram-negative isolates were collected from different microbiological laboratories, during the period January 2010 till January 2012. Among these gram-negative isolates, 125 were identified as Klebsiella species. After species identification, Kirby Bauer disk diffusion method was used for antimicrobial susceptibility profiling. Furthermore, the phenotypic detection of ESBL producers was performed by double disc synergy and combination disc methods. Resistance genes responsible for the production of beta lactamase and extended spectrum beta lactamase enzymes were detected by Polymerase chain reaction. DNA sequencing was performed by selecting an ESBL producing Klebsiella pneumoniae strain with a positive blaTEM gene. RESULTS: In this study, we found 48%, 43.2% and 2.4% of SHV, TEM, and CTX-M resistance genes respectively in Klebsiella isolates. The DNA sequence ESBL and blaTEM positive Klebsiella strain showed 94% similarity with Klebsiella pneumoniae KUN5033 blaTEM gene for class A beta-lactamase TEM-198 analyzed by the Basic Local Alignment Search Tool (BLAST). CONCLUSION: Since there is an intense need of research in the field of drug resistance for implementing strict antibiotic control policies in hospitals, health care centers, laboratories, etc., the present study is dedicatedly conducted to estimate the drug resistant Klebsiella isolates, specifically the Beta lactamase and Extended Spectrum Beta Lactamase producers, at molecular level.