Vineeth Rajan | Anna University (original) (raw)

Papers by Vineeth Rajan

Research paper thumbnail of Non-diarrhoeic pigs as source of highly virulent and multidrug-resistant non-typhoidal Salmonella

Brazilian Journal of Microbiology, 2022

Food-producing animals act as reservoirs of non-typhoidal Salmonella (NTS) serovars with potentia... more Food-producing animals act as reservoirs of non-typhoidal Salmonella (NTS) serovars with potential food safety and public health implications. The present cross-sectional study aimed at determining the prevalence of Salmonella serotypes in non-diarrhoeic pigs and characterizing the isolates using molecular tools. Salmonella isolates (n = 22) recovered from faecal samples of 194 randomly selected pigs were characterized for virulence and antimicrobial resistance and subtyped using XbaI-PFGE. The prevalence of Salmonella in apparently healthy non-diarrhoeic pigs was 11.3% (95%CI, 4.3-19.5%), with S. Weltevreden (81.8%) and S. Enteritidis (18.2%) being the serotypes detected. Salmonella isolates harboured virulence genes such as invA (100%), stn (100%), spvR/spvC (86.3%) and fimA (22.7%). Phenotypically, isolates showed sensitivity to chloramphenicol, levofloxacin and ciprofloxacin and resistance to tetracycline and ampicillin (100%), streptomycin (86.4%), amoxicillin-clavulanate (63.6%), cefotaxime (22.7%) and ceftriaxone (9.1%). Notably, 18.2% isolates were multidrug-resistant (≥ 3 antimicrobial class) with multiple antimicrobial resistance (MAR) index of 0.56-0.67 (18.2%), 0.44 (45.5%), 0.33 (31.8%) and 0.22 (4.5%). Genotypically, isolates carried various antibiotic resistance genes: ESBL (blaTEM and blaOXA), aminoglycoside (strA, strB and aadA1), sulphonamide (sul1, sul2 and dfrA1), tetracycline (tetA and tetB) and plasmid AmpC beta-lactamase (ACC, FOX, MOX, DHA, CIT and EBC). The present investigation emphasizes the epidemiological significance of PFGE typing in the detection of emerging strains of highly virulent and multidrug-resistant S. Weltevreden and S. Enteritidis in non-diarrhoeic pigs that pose serious public health implications in the pork supply chain environment. More extensive longitudinal study is warranted to provide epidemiological links between environmental reservoirs and animal and human infections in piggery settings.

Research paper thumbnail of Genotypes and phenotypes of methicillin-resistant staphylococci isolated from shrimp aquaculture farms

Environmental microbiology reports, 2021

The population of methicillin-resistant (MR) staphylococci in aquatic environment is rarely inves... more The population of methicillin-resistant (MR) staphylococci in aquatic environment is rarely investigated. Here, we characterized a collection of MR staphylococci recovered from shrimp aquaculture farms (n = 37) in Kerala, India. A total of 261 samples yielded 47 MR isolates (16 S. aureus, 13 S. haemolyticus, 11 S. epidermidis, 3 S. saprophytics and 2 each of S.intermedius and S. kloosii). Multi-drug resistance was evident in 72.3% of the isolates, with resistance mainly towards erythromycin (78.7%), norfloxacin and trimethoprim-sulfamethoxazole (53.2%), and gentamicin (34%). Major resistance genes identified included mecA (100%), ermC (38.3%), aacA-aphD (21.3%), tetK (14.9%) and tetM (21.3%). Almost 60% of the isolates carried type V SCCmec (Staphylococcal Cassette Chromosome mec), and the remaining harboured untypeable SCCmec elements. Comprehensive genotyping of the methicillin-resistant Staphylococcus aureus isolates revealed high prevalence of ST772-t345-V (sequence type-spa typ...

Research paper thumbnail of Antibiotic Resistance Profiles and Molecular Characteristics of Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli and Klebsiella pneumoniae Isolated From Shrimp Aquaculture Farms in Kerala, India

Frontiers in Microbiology, 2021

This study was undertaken to evaluate the prevalence of extended-spectrum beta-lactamase (ESBL)-p... more This study was undertaken to evaluate the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae in selected shrimp aquaculture farms (n = 37) in Kerala, South India and to characterize the isolates using molecular tools. Overall, a low prevalence of ESBL-producers was found in the farms, most likely due to the reduced antibiotic usage in the shrimp farming sector. Out of the 261 samples (77 shrimp and 92 each of water and sediment), 14 (5.4%) tested positive for ESBL-E. coli or ESBL-K. pneumoniae. A total of 32 ESBL-E. coli and 15 ESBL- K. pneumoniae were recovered from these samples. All ESBL isolates were cefotaxime-resistant with minimal inhibitory concentration (MIC) ≥32 μg/ml. Of all isolates, 9 (28.1%) E. coli and 13 (86.7%) K. pneumoniae showed simultaneous resistance to tetracycline, ciprofloxacin, and trimethoprim-sulfamethoxazole. PCR analysis identified CTX-M group 1 (blaCTX–M–15) as the predominant ESBL genotype in bot...

Research paper thumbnail of Genotyping of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) in a tertiary care centre in Mysore, South India: ST2371-SCCmec IV emerges as the major clone

Infection, Genetics and Evolution, 2015

The burden of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) is on th... more The burden of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) is on the rise in population and clinical settings on account of the adaptability and virulence traits of this pathogen. We characterized 45 non-duplicate CA-MRSA strains implicated mainly in skin and soft tissue infections (SSTIs) in a tertiary care hospital in Mysore, South India. All the isolates were genotyped by staphylococcal cassette chromosome mec (SCCmec) typing, staphylococcal protein A (spa) typing, accessory gene regulator (agr) typing, and multi-locus sequence typing (MLST). Four sequence types (STs) belonging to three major clonal complexes (CCs) were identified among the isolates: CC22 (ST2371 and ST22), CC1 (ST772) and CC8 (ST8). The majority (53.3%) of the isolates was of the genotype ST2371-t852-SCCmec IV [sequence type-spa type-SCCmec type], followed by ST22-t852-SCCmec IV (22.2%), ST772-t657-SCCmec V (13.3%) and ST8-t008-SCCmec IV (11.1%). ST237I, a single locus variant of ST22 (EMRSA-15 clone), has not been reported previously from any of the Asian countries. Our study also documents for the first time, the appearance of ST8-SCCmec IV (USA300) strains in India. Representative strains of the STs were further analyzed by pulsed field gel electrophoresis (PFGE). agr typing detected type I or II alleles in the majority of the isolates. All the isolates were positive for the leukotoxin gene, pvl (Panton-Valentine leukocidin) and the staphylococcal enterotoxin gene cluster, egc. Interestingly, multidrug resistance (resistance to P3 classes of non-beta-lactam antibiotics) was observed in 77.8% (n = 35) of the isolates. The highest (75.5%) resistance was recorded for ciprofloxacin, followed by erythromycin (53.3%), and quinupristindalfopristin (51.1%). Inducible clindamycin-resistance was identified in 37.7% of the isolates and it was attributed to the presence of erm(A), erm(C) and a combination of erm(A) and erm(C) genes. Isolates which showed a phenotypic pattern of M R /L S (macrolide-resistance/lincosamide-sensitivity) harbored the msr(A) gene. In conclusion, we report a high rate of multidrug resistance among Indian strains of CA-MRSA and the emergence of the lineages ST2371 and ST8 in India.

Research paper thumbnail of Non-diarrhoeic pigs as source of highly virulent and multidrug-resistant non-typhoidal Salmonella

Brazilian Journal of Microbiology, 2022

Food-producing animals act as reservoirs of non-typhoidal Salmonella (NTS) serovars with potentia... more Food-producing animals act as reservoirs of non-typhoidal Salmonella (NTS) serovars with potential food safety and public health implications. The present cross-sectional study aimed at determining the prevalence of Salmonella serotypes in non-diarrhoeic pigs and characterizing the isolates using molecular tools. Salmonella isolates (n = 22) recovered from faecal samples of 194 randomly selected pigs were characterized for virulence and antimicrobial resistance and subtyped using XbaI-PFGE. The prevalence of Salmonella in apparently healthy non-diarrhoeic pigs was 11.3% (95%CI, 4.3-19.5%), with S. Weltevreden (81.8%) and S. Enteritidis (18.2%) being the serotypes detected. Salmonella isolates harboured virulence genes such as invA (100%), stn (100%), spvR/spvC (86.3%) and fimA (22.7%). Phenotypically, isolates showed sensitivity to chloramphenicol, levofloxacin and ciprofloxacin and resistance to tetracycline and ampicillin (100%), streptomycin (86.4%), amoxicillin-clavulanate (63.6%), cefotaxime (22.7%) and ceftriaxone (9.1%). Notably, 18.2% isolates were multidrug-resistant (≥ 3 antimicrobial class) with multiple antimicrobial resistance (MAR) index of 0.56-0.67 (18.2%), 0.44 (45.5%), 0.33 (31.8%) and 0.22 (4.5%). Genotypically, isolates carried various antibiotic resistance genes: ESBL (blaTEM and blaOXA), aminoglycoside (strA, strB and aadA1), sulphonamide (sul1, sul2 and dfrA1), tetracycline (tetA and tetB) and plasmid AmpC beta-lactamase (ACC, FOX, MOX, DHA, CIT and EBC). The present investigation emphasizes the epidemiological significance of PFGE typing in the detection of emerging strains of highly virulent and multidrug-resistant S. Weltevreden and S. Enteritidis in non-diarrhoeic pigs that pose serious public health implications in the pork supply chain environment. More extensive longitudinal study is warranted to provide epidemiological links between environmental reservoirs and animal and human infections in piggery settings.

Research paper thumbnail of Genotypes and phenotypes of methicillin-resistant staphylococci isolated from shrimp aquaculture farms

Environmental microbiology reports, 2021

The population of methicillin-resistant (MR) staphylococci in aquatic environment is rarely inves... more The population of methicillin-resistant (MR) staphylococci in aquatic environment is rarely investigated. Here, we characterized a collection of MR staphylococci recovered from shrimp aquaculture farms (n = 37) in Kerala, India. A total of 261 samples yielded 47 MR isolates (16 S. aureus, 13 S. haemolyticus, 11 S. epidermidis, 3 S. saprophytics and 2 each of S.intermedius and S. kloosii). Multi-drug resistance was evident in 72.3% of the isolates, with resistance mainly towards erythromycin (78.7%), norfloxacin and trimethoprim-sulfamethoxazole (53.2%), and gentamicin (34%). Major resistance genes identified included mecA (100%), ermC (38.3%), aacA-aphD (21.3%), tetK (14.9%) and tetM (21.3%). Almost 60% of the isolates carried type V SCCmec (Staphylococcal Cassette Chromosome mec), and the remaining harboured untypeable SCCmec elements. Comprehensive genotyping of the methicillin-resistant Staphylococcus aureus isolates revealed high prevalence of ST772-t345-V (sequence type-spa typ...

Research paper thumbnail of Antibiotic Resistance Profiles and Molecular Characteristics of Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli and Klebsiella pneumoniae Isolated From Shrimp Aquaculture Farms in Kerala, India

Frontiers in Microbiology, 2021

This study was undertaken to evaluate the prevalence of extended-spectrum beta-lactamase (ESBL)-p... more This study was undertaken to evaluate the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae in selected shrimp aquaculture farms (n = 37) in Kerala, South India and to characterize the isolates using molecular tools. Overall, a low prevalence of ESBL-producers was found in the farms, most likely due to the reduced antibiotic usage in the shrimp farming sector. Out of the 261 samples (77 shrimp and 92 each of water and sediment), 14 (5.4%) tested positive for ESBL-E. coli or ESBL-K. pneumoniae. A total of 32 ESBL-E. coli and 15 ESBL- K. pneumoniae were recovered from these samples. All ESBL isolates were cefotaxime-resistant with minimal inhibitory concentration (MIC) ≥32 μg/ml. Of all isolates, 9 (28.1%) E. coli and 13 (86.7%) K. pneumoniae showed simultaneous resistance to tetracycline, ciprofloxacin, and trimethoprim-sulfamethoxazole. PCR analysis identified CTX-M group 1 (blaCTX–M–15) as the predominant ESBL genotype in bot...

Research paper thumbnail of Genotyping of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) in a tertiary care centre in Mysore, South India: ST2371-SCCmec IV emerges as the major clone

Infection, Genetics and Evolution, 2015

The burden of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) is on th... more The burden of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) is on the rise in population and clinical settings on account of the adaptability and virulence traits of this pathogen. We characterized 45 non-duplicate CA-MRSA strains implicated mainly in skin and soft tissue infections (SSTIs) in a tertiary care hospital in Mysore, South India. All the isolates were genotyped by staphylococcal cassette chromosome mec (SCCmec) typing, staphylococcal protein A (spa) typing, accessory gene regulator (agr) typing, and multi-locus sequence typing (MLST). Four sequence types (STs) belonging to three major clonal complexes (CCs) were identified among the isolates: CC22 (ST2371 and ST22), CC1 (ST772) and CC8 (ST8). The majority (53.3%) of the isolates was of the genotype ST2371-t852-SCCmec IV [sequence type-spa type-SCCmec type], followed by ST22-t852-SCCmec IV (22.2%), ST772-t657-SCCmec V (13.3%) and ST8-t008-SCCmec IV (11.1%). ST237I, a single locus variant of ST22 (EMRSA-15 clone), has not been reported previously from any of the Asian countries. Our study also documents for the first time, the appearance of ST8-SCCmec IV (USA300) strains in India. Representative strains of the STs were further analyzed by pulsed field gel electrophoresis (PFGE). agr typing detected type I or II alleles in the majority of the isolates. All the isolates were positive for the leukotoxin gene, pvl (Panton-Valentine leukocidin) and the staphylococcal enterotoxin gene cluster, egc. Interestingly, multidrug resistance (resistance to P3 classes of non-beta-lactam antibiotics) was observed in 77.8% (n = 35) of the isolates. The highest (75.5%) resistance was recorded for ciprofloxacin, followed by erythromycin (53.3%), and quinupristindalfopristin (51.1%). Inducible clindamycin-resistance was identified in 37.7% of the isolates and it was attributed to the presence of erm(A), erm(C) and a combination of erm(A) and erm(C) genes. Isolates which showed a phenotypic pattern of M R /L S (macrolide-resistance/lincosamide-sensitivity) harbored the msr(A) gene. In conclusion, we report a high rate of multidrug resistance among Indian strains of CA-MRSA and the emergence of the lineages ST2371 and ST8 in India.