A secular trend in invasive non-typhoidal Salmonella in South India, 2000-2020: Identification challenges and antibiogram.

PURPOSE: Invasive non-typhoidal Salmonella (iNTS) disease is an important cause of morbidity and mortality in African countries. However, the incidence in Indian subcontinent remains poorly documented. This study has assessed the incidence of iNTS in India with a perspective on its AMR profiles and serovar distribution for a period of 21 years from 2000 to 2020 from a tertiary care centre in South India. METHODS: A total of 461 iNTS isolates were subjected to serotyping and antimicrobial susceptibility testing (AST). A subset of isolates was genotyped by multi locus sequence typing (MLST) and results were compared to serotyping to predict the accuracy. RESULTS: Overall, 461 iNTS isolates were characterised mostly comprising of S. Typhimurium (49.2%) and S. Enteritidis (28.8%). Proportion of isolates resistant to first line antibiotics such as ampicillin, chloramphenicol and trimethoprim/sulphamethoxazole were 6.7%, 1.7% and 3.6% respectively. Isolates resistant to third generation cephalosporin are at a gradual rise while decreased susceptibility to quinolones was most common. The incidence of iNTS infection was maximum in the age group of >15 years. MLST analysis showed discrepancies in assigning the serovars by serotyping as three S. Saintpaul were identified as S. Typhimurium. CONCLUSION: The clinical epidemiology, serovar distribution and antimicrobial susceptibility patterns of invasive Salmonella isolates from India suggest that there is only a small burden of iNTS disease. However the gradual emergence of AMR in iNTS isolates indicates serious risk for public health warranting the importance enhanced molecular surveillance.

Draft genome sequences data of rare Salmonella enterica sub sp. enterica serovar Ceyco and serovar Hillegersberg isolated from diarrheal patients in India.

We report here the draft genome sequence of two rare Salmonella serotypes, isolated from human faecal samples in India. The isolates were identified as Salmonella enterica subsp. enterica serovar Ceyco and serovar Hillegersberg by Wole genome sequencing (WGS) based serotype prediction. The genomic similarity of study isolates was identified by clustering with the global collection of Salmonella sp. available in EnteroBase and SISTR based on their cgMLST profile. Phylogenetic analysis showed the study isolates were closer to S. Detmold and other unknown serovars from serogroup D2 . The information generated from genome sequencing of two rare S. enterica serovar will improve the overall understanding of the epidemiology of this clinically relevant pathogen.

A nineteen-year report of serotype and antimicrobial susceptibility of enteric non-typhoidal Salmonella from humans in Southern India: changing facades of taxonomy and resistance trend.

BACKGROUND: The steady increase in the proportion of Non-typhoidal Salmonella (NTS) infections in humans represents a major health problem worldwide. The current study investigated the serovar distribution and antimicrobial susceptibility trends of NTS isolated from faecal samples during the period 2000-2018. METHODS: Faecal specimens of patients were cultured according to standard lab protocol. The isolates were serotyped and antimicrobial susceptibility testing (AST) were performed according to CLSI guidelines. RESULTS: A total of 1436 NTS isolates were obtained from faeces samples mostly comprising of S. Typhimurium (27.3%), S. Weltevreden (13%), S. Bareilly (11%), S. Newport (4.2%), S. Cholerasuis (4%), S. Infantis (3.4%), and S. Enteritidis (2.4%). Resistance to nalidixic acid (26%) was most common among the tested NTS, followed by ampicillin (18.5%), cotrimoxazole (13.5%), ciprofloxacin (12%), ceftriaxone (6.3%) and chloramphenicol (3.6%). Multidrug resistance was observed in 5% of NTS isolates with the highest rate (10.52%) in 2014. The incidence of NTS infection was maximum in children < 5 years of age with an average 19.3% of the total affected patients during the time period. CONCLUSIONS: Based on this study, the faecal NTS isolates have high resistance rates against first line antimicrobial agents except chloramphenicol. The gradual but consistent increase in resistance to fluoroquinolones, third generation cephalosporins and macrolide may restrict future treatment options. Hence periodic monitoring of NTS infections, serotype distribution and antimicrobial resistance trend is recommended.