Complete genome sequence analysis of multi-drug resistant Klebsiella pneumoniae THK strain isolated from aquaculture farm in Kerala, India.

The emergence of microorganisms with resistance toward antibiotics has been widely recognized as a growing hazard to public health. Here, we report the whole genome sequence of Klebsiella pneumoniae strain THK, which was isolated from an aquaculture farm in Kerala, India. Standard disc diffusion and strip methods were used for antibiotic susceptibility testing and minimum inhibitory concentration detection. The isolate showed high level of resistance against beta-lactam, aminoglycosides, fluoroquinolones, macrolides, tetracyclines, chloramphenicol, sulfonamides, and cephalosporin class of antibiotics, but were sensitive to carbapenem and polymyxins. The whole genome sequence analysis revealed that the final assembly of THK strain consisted of 30 contigs of 5, 199,186 bp including four plasmid sequences plasmid_690 (1 contig), plasmid_710 (9 contigs), plasmid_1222 (6 contigs), and plasmid_1528 (1 contig). Sequence analysis revealed that the isolate has a number of genes encoding for antibiotic resistance and virulence. The findings indicated that antibiotics present in aquatic environments at sub-inhibitory concentrations increase the selection pressure affecting the cell function of even normal aquatic microorganisms to change the genetic expression of virulence factors or acquire resistance genes through various transfer mechanisms. This strain would be of significant interest for thorough comparative genomic study, given the known vast diversity of pathogenic and antibiotic resistance potentials.

Isolation and identification of Streptococcus agalactiae in cage-cultured green chromide Etroplus suratensis in Kerala, India.

Streptococcus agalactiae is one of the main aetiological agents in large-scale mortalities of tilapia, having caused major economic losses to the aquaculture industry in recent years. This study describes the isolation and identification of the bacteria from cage-cultured Etroplus suratensis that experienced moderate to severe mortalities in Kerala, India. Gram-positive, catalase-negative S. agalactiae was identified from brain, eye and liver of the fish by antigen grouping and 16S rDNA sequencing. Multiplex PCR confirmed that the isolate belonged to capsular serotype Ia. Antibiotic susceptibility tests showed that the isolate was resistant to methicillin, vancomycin, tetracycline, kanamycin, streptomycin, ampicillin, oxacillin and amikacin. Histological sections of the infected E. suratensis brain revealed infiltration of inflammatory cells, vacuolation and meningitis. This report is the first description of S. agalactiae as a primary pathogen causing mortalities in E. suratensis culture in Kerala.

Genetic diversity and prevalence of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae in aquatic environments receiving untreated hospital effluents.

The spread of extended-spectrum beta-lactamase (ESBL)-producing bacteria in the environment has been recognized as a challenge to public health. The aim of the present study was to assess the occurrence of ESBL-producing Escherichia coli and Klebsiella pneumoniae from selected water bodies receiving hospital effluents in Kerala, India. Nearly 69.8% of Enterobacteriaceae isolates were multi-drug resistant by the Kirby-Bauer disc diffusion method. The double disc synergy test was used to detect the ESBL production and the genes responsible for imparting resistance were detected by PCR. Conjugation experiments confirmed the mechanism of plasmid-mediated transfer of resistance. The prevalence of ESBL production in E. coli and K. pneumoniae was 49.2 and 46.8%, respectively. Among the ESBL-encoding genes, blaCTX-M was the most prevalent group followed by blaTEM, blaOXA, blaCMY, and blaSHV. The results suggest that healthcare settings are one of the key contributors to the spread of ESBL-producing bacteria, not only through cross-transmission and ingestion of antibiotics but also through the discharge of waste without a proper treatment, leading to harmful effects on the aquatic environment. The high prevalence of ESBL-producing Enterobacteriaceae with resistance genes in public water bodies even post-treatment poses a serious threat.

Identification and characterization of vancomycin-resistant Staphylococcus aureus in hospital wastewaters: evidence of horizontal spread of antimicrobial resistance.

Antibiotic resistance has become a major threat to human health around the world, but its spread through the aquatic environment has been often overlooked. This study aimed to determine the occurrence of vancomycin-resistant Staphylococcus aureus in hospital wastewaters and their transmission into public water bodies in Kerala, India. A total of 113 S. aureus were isolated from three hospital effluents in Kerala, India. Standard disc diffusion and the strip method were used for antibiotic susceptibility testing and minimum inhibitory concentration detection. Plasmid-mediated vancomycin resistance was confirmed by plasmid curing and conjugation; resistant genes were detected by the polymerase chain reaction (PCR). Nearly 76% of S. aureus isolates were resistant to ß-lactams, chloramphenicol, macrolides, aminoglycosides, and glycopeptide class of antibiotics. Among the vancomycin-resistant Staphylococcus aureus (VRSA) isolates, the prevalence rates of vanA and vanB resistance-encoding genes were 46.5 and 59.3%, respectively. Through the broth mating method, vanA gene was successfully transferred from VRSA donor to vancomycin-sensitive S. aureus. The study strongly indicates the contamination of water bodies with antibiotic-resistant bacteria from hospital discharges, their dissemination and possible transfer to microbes in the aquatic environment, posing a serious threat for public health.

Investigating the impact of hospital antibiotic usage on aquatic environment and aquaculture systems: A molecular study of quinolone resistance in Escherichia coli.

Quinolones are one of the most important classes of antibacterials available for the treatment of infectious diseases in humans. However, there is a growing concern about bacterial resistance to antimicrobials including quinolones. The spread of antibiotic-resistant bacteria in the aquatic environment has been recognized as a growing threat to public health and hospitals appear to be a major contributor to this. The objective of this study was to investigate the prevalence of quinolone resistance in Escherichia coli from selected water bodies receiving direct hospital effluents in Kerala, India. Standard disc diffusion and E-test were used for antibiotic susceptibility testing. As antibiotic resistance can develop in bacterial isolates by different means, EtBr Agar Cartwheel method was used to detect the efflux pump activity and presence of resistant genes was detected by PCR. The mechanism of transfer of plasmid mediated resistance was confirmed by conjugation experiments. A total of 209 multidrug-resistant Escherichia coli were isolated from different hospital effluent discharge sites and aquaculture farms located in their vicinity. Among them, qnrB was found to be most prevalent followed by qnrS, OqxAB, qnrA and aac (6')-Ib-cr. The results suggested that the antibiotics present at sub-inhibitory concentrations in direct hospital effluents increases the selection pressure impacting the cell function of even normal microorganisms in the aquatic environment to change the genetic expression of virulence factors or acquire resistance genes by different transfer mechanisms, posing a serious threat to public health.