Prasanth Manohar
Profile Url: prasanth-manohar
Researcher at VIT University
0
0
0
Video Abstract (AI generated)
Paper
Preprint
Carbapenem resistance in Gram-negative bacteria is an ongoing public-health problem of global dimensions leaving very few treatment options for severely infected patients. This study focuses on the dissemination of plasmid-borne carbapenemase genes in Gram-negative bacteria in Tamil Nadu, India. A total of 151 non-repetitive isolates belonging to 11 genera were collected from a diagnostic center in Tamil Nadu. E. coli (n=57) isolates were classified as, Enteropathogenic (n=12), Enteroaggregative (n=9), Enterohemorrhagic (n=8), Enterotoxigenic (n=3), Enteroinvasive (n=1) and unclassified E. coli (n=24). Of the 45 Klebsiella species, 14 were K1 whereas 11 were K2 serotype and in 20 Klebsiella serotype could not be determined. Other isolates (n=49) consisted of P. aeruginosa, S. typhi, E. cloacae, A. baumannii, S. marcescens, A. xylosoxidans, P. mirabilis and E. meningoseptica. Of the 151 isolates, 71% (n=107) and 68% (n=103) were found to be resistant to meropenem and imipenem respectively. The most prevalent beta-lactamase gene was blaNDM-1 (21%, 12/57) followed by blaOXA-181 (16%, 9/57), blaGES-9 (n=8), blaOXA-23 (n=7), blaIMP-1 (n=3), blaGES-1 (n=11) and blaOXA-51 (n=9). The unusual presence of blaOXA-23 was seen in E. coli (n=4), and blaOXA-23 and blaOXA-51 (IncA/C) in K. pneumoniae (n=3). Plasmid incompatibility (inc/rep) typing results showed that the plasmids carrying resistance genes (n=11) belonged to IncX, IncA/C, IncFIA-FIB and IncFIIA groups. E. coli and K. pneumoniae were able to transfer plasmid-borne carbapenemase via conjugation. This study highlights the prevalence of carbapenem resistance and the acquisition of plasmid-borne carbapenemase genes in Gram-negative bacteria highlighting the role of plasmid transfer in disseminating resistance.
0
0
0
Video Abstract (AI generated)
Paper
Preprint
Supplementary Table 1
The emergence of antibiotic resistance due to the uncontrolled use of antibiotics in non-humans poses a major threat for treating bacterial infections in humans. Added to this is the possibility of transfer of resistance from Gram-positive bacteria to Gram-negative bacteria. Therefore, the possibility of resistance gene transfer from a non-human originated pathogenic bacterium to a pathogenic bacterium infecting humans needs evaluation. In this study, poultry litter samples collected from Tamil Nadu, India were screened for the presence of meropenem- and cefotaxime-resistant Staphylococcus sciuri. Standard microbiological techniques and 16S rRNA analysis were used to confirm S. sciuri. In the resistant isolates, resistance genes such as blaNDM-1, blaOXA-48-like, blaKPC, blaVIM, blaIMP and blaCTX-M were screened. Transconjugation studies were performed using donor, S. sciuri and recipient, E. coli AB1157 (Strr). A total of 26 meropenem-resistant and 24 cefotaxime resistant S. sciuri were isolated from poultry litter samples. The presence of blaNDM-1 (n=2), blaIMP (n=8), blaCTX-M-9 (n=5) and blaCTX-M-2 (n=1) was detected. Transconjugation results confirmed that S. sciuri carrying plasmid-borne resistance gene blaNDM-1 conjugated to E. coli AB1157. The transferability of resistance genes from S. sciuri to E. coli could be another possible reason for the spread of antibiotic-resistant bacteria in humans. ### Competing Interest Statement The authors have declared no competing interest.
0
0
0
Video Abstract (AI generated)
Paper
Preprint
Background: Emergence of carbapenem resistance mechanisms among Gram-negative bacteria is a worrisome health problem. Here, we focused on to identify the presence of carbapenem-resistant bacteria among the samples collected from hospital environments in Tamil Nadu. Methods: A total of 30 hospital environmental samples were collected between August 2017 and January 2018 from hospitals located in Chennai and Vellore such as lift switches, stair rails, switchboards, nursing desks, used nursing gloves, door handles, wheelchairs, touch screens, chairs and from pillars inside the hospitals. Results and discussion: A total of 22 carbapenem-resistant Gram-negative bacteria were isolated that included Escherichia coli, Klebsiella sp., Enterobacter sp., Salmonella sp., Pseudomonas aeruginosa and Acinetobacter sp. Interestingly, blaGIM-1 was detected in Acinetobacter variabilis strain isolated in samples collected from hospitals. Unlike other studies, the identified GIM-1 was not plasmid encoded, and this is the first report for the presence of GIM-1 (German imipenemase) in India. Conclusion: Extensive surveillance programs are necessary to trace the uncontrolled spread of carbapenem-resistance genes in order to reduce the rapid spread of resistance.
0
0
0
Video Abstract (AI generated)
Paper
Preprint
To evaluate the presence of biofilm-specific antibiotic-resistant genes, PA0756-0757, PA5033 and PA2070 in Pseudomonas aeruginosa isolated from clinical samples in Tamil Nadu. For this cross-sectional study, 24 clinical isolates (included pus, urine, wound, and blood) were collected from two diagnostic centres in Chennai from May 2015 to February 2016. Biofilm formation was assessed using microtiter dish biofilm formation assay and minimal inhibitory concentration (MIC) and minimal bactericidal concentrations (MBC) were determined for planktonic and biofilm cells (MBC assay). Further, PCR amplification of biofilm-specific antibiotic resistance genes PA0756-0757, PA5033 and PA2070 were performed. Biofilm formation was found to be moderate/strong in 16 strains. MBC for planktonic cells showed that 4, 7, 10 and 14 strains were susceptible to gentamicin, ciprofloxacin, meropenem and colistin respectively. In MBC assay for biofilm cells (MBC-B), all the 16 biofilm producing strains were resistant to ciprofloxacin and gentamicin whereas nine and four were resistant to meropenem, and colistin respectively. The biofilm-specific antibiotic-resistant genes PA0756-0757 was found in 10 strains, 6 strains with PA5033 and 9 strains with PA2070 that were found to be resistant phenotypically. This study highlighted the importance of biofilm-specific antibiotic resistance genes PA0756-0757, PA5033, and PA2070 in biofilm-forming P. aeruginosa.
0
0
0
Video Abstract (AI generated)
Paper
Preprint
The distribution of carbapenem-resistant Gram-negative bacteria has become an increasing public health concern in India. The aim of this study was to investigate the prevalence of carbapenem-resistant bacteria isolated from the clinical samples in Tamil Nadu, India. A total of 126 non-repetitive Gram-negative bacteria were taken for this study. The susceptibility to meropenem was determined by Minimum Inhibitory Concentration (MIC) by broth microdilution. The phenotypic resistance screening such as MHT (Modified Hodge test), EDTA disk synergy and CIM (carbapenem inactivation method) were performed. A multiplex PCR was used for the detection of carbapenemase-encoding genes. Among the 126 isolates studied, 82 (65.07%) meropenem-resistant isolates were identified by MIC. A total of 18 (21.9%) isolates were found to be positive for Metallo-{beta}-Lactamase production through EDTA synergy test. None of the isolates were carbapenemase producer by MHT and CIM. The isolates identified with resistance genes (8/82) were blaNDM-1 in two Klebsiella sp., two P. aeruginosa and one A. baumannii, blaVIM-1 in one P. aeruginosa and blaAIM-1 in one P. aeruginosa and one A. baumannii. The study showed the distribution and increase of carbapenem-resistant bacteria in the study region. Therefore, constant monitoring and effective elimination should be focused to reduce the spread of carbapenem-resistant isolates.
0
0
0
Frontiers in Microbiology, 2020-12-03
Video Abstract (AI generated)
Paper
Preprint
Supplementary figure
Supplementary sheet 1
Supplementary sheet 2
Frontiers in Microbiology
Acinetobacter baumannii is of major clinical importance as the bacterial pathogen often causes hospital acquired infections, further complicated by the high prevalence of antibiotic resistant strains. Aside from natural tolerance to certain antibiotic classes, resistance is often acquired by the exchange of genetic information via conjugation but also by the high natural competence exhibited by A. baumannii. In addition, bacteriophages are able to introduce resistance genes but also toxins and virulence factors via phage mediated transduction. In this work, we analysed the complete genomes of 177 A. baumannii strains for the occurrence of prophages, and analysed their taxonomy, size and positions of insertion. Among all the prophages that were detected, Siphoviridae and Myoviridae were the two most commonly found families, while the average genome size was determined as 3.98 Mbp. Our data shows the wide variation in the number of prophages in A. baumannii genomes and the prevalence of certain prophages within strains that are most successful or potentially beneficial to the host. Our study also revealed that only two specific sites of insertion within the genome of the host bacterium are being used, with few exceptions only. Lastly, we analysed the existence of genes that are encoded in the prophages, which confer antimicrobial resistance (AMR). Several phages carry AMR genes, including OXA-23 and NDM-1, illustrating the importance of lysogenic phages in the acquisition of resistance genes. ### Competing Interest Statement The authors have declared no competing interest.
Loading Projects...