Clinical-Microbiological Study of Nontyphoidal Salmonella Infections from Karnataka, India

Nontyphoidal salmonella (NTS) are responsible for food-borne gastroenteritis and bacteremia, in immunosuppressed individuals. Antibiotic resistance in NTS is on the rise. This study reports the prevalence and antimicrobial susceptibility of nontyphoidal salmonella in clinical samples. Study Design. This is a hospital record-based cross-sectional, retrospective study.

In our study, inpatient samples such as blood (n = 13546), urine (n = 11,333), pus (n = 1,010), and stool (n = 926) samples were cultured to isolate etiological agents in the microbiology department from January 2017 to June 2019. Relevant details such as duration of fever, platelet count, hemoglobin, WBC count, immune status, and mode of treatment were noted from the medical records. Data were analyzed, and continuous variables were expressed as mean and categorical variables as percentages.

A total of 24 NTS serovars were isolated, which included ten isolates from blood, five each from urine and pus, and four from stool samples. Of the NTS, five were Salmonella enterica subsp. enterica, three were S.enterica serovar Typhimurium, one was S.enterica subsp. diarizonae, and 15 S.enterica serovars could not be serologically differentiated. All were susceptible to ampicillin, chloramphenicol, and cefuroxime. However, 16.6% of NTS was resistant to ceftriaxone, 4% to cotrimoxazole, 58% to ciprofloxacin, and 75% to nalidixic acid.

A low prevalence of NTS responsible for invasive infections is seen in this part of the country. Few isolates were resistant to more than one antibiotic. A higher rate of resistance to ceftriaxone is the cause of concern. Awareness of the distribution of NTS serogroups is of epidemiological and public health significance.