Serovar Profile and Detection of Inva Virulence Gene Among Non-Typhoidal Salmonellae Serovars Isolated From Acute Gastroenteritis Cases in Coastal Karnataka, Southern India

Abstract

Objective: Non-typhoidal salmonellosis is one of the leading zoonosis in the world caused by non-typhoidal Salmonella (NTS). Invasive infections with NTS serovars occurs due to the presence of virulence genes like invA along with the immunosuppressive conditions of the patient. The study was conducted to isolate and identify the NTS serovars and their antimicrobial resistance profile from patients with diarrhea and also to detect the virulence marker -invA gene among these NTS serovars.Methods: A prospective cross-sectional study was conducted from January 2015 to December 2016 at the Enteric Diseases Division, Kasturba Medical College, Manipal. 1218 fecal specimens were collected from patients with diarrhea and before antibiotic treatment. NTS serovars were identified, serotyped and then screened for the presence of invA virulence gene.Results: A total of 33 (2.7%) NTS was isolated. Salmonella typhimurium (33.34%) was predominant followed by Salmonella oslo (30.3%). Out of 33 NTS, invA was positive for 28 isolates (84.8%) of which 25 (89.3%) patients were febrile which was statistically significant (p=0.000). Conclusion:Non-typhoidal salmonellosis is an emerging global infection among immunocompromised patients. Our study showed an association between the invA gene and febrile illness among the patients suffering. Thus, this study highlights the importance of invA as a significant marker for bloodstream invasion.

Poultry: A receptacle for non-typhoidal Salmonellae and antimicrobial resistance

“…invA, spvR, spvC, fimA and stnare some of the virulence genes of NTS. invA gene is a unit of the SPI 1 which encodes a protein in the inner membrane of bacteria which is responsible invasion to the epithelial cells of the host (2). The PCR assay for the detection of invA gene showed a proportion of 74.13% (43/58) which is lesser in comparison with other studies carried out where invA gene was present in all the NTS isolates (10, 26).…”

“…In our study, seventy-four percent of the NTS serovars were positive for the presence of invA gene which codes for invasion and survival in macrophages and in the internalization needed for the invasion of deeper tissue there by causing invasive infections. Research carried out also proposes that the primary food consumed by the patients suffering from non-typhoidal salmonellosis was found to be poultry products such as chicken meat and eggs (72.7%) (2). Centers for Disease Control and Prevention (CDC) as of July 13, 2018, reported multistate outbreaks of NTS linked to contact with live poultry.…”

“…They are also found in frogs, toads, rodents and other birds like parakeets, parrots and wild birds. These reservoirs of Salmonella can cause the disease to humans termed as non-typhoidal salmonellosis (NTS) (1, 2). Human beings obtain this infection through the ingestion of raw or undercooked contaminated food from animal origin, mainly from poultry (eggs and meat), pigs (meat) and by the consumption of unpasteurized cow milk.…”

“…The symptoms include diarrhea, vomiting and abdominal cramps which develop 12 to 72 hours after infection. NTS have a discrete adaptation to certain animals such as Salmonella Choleraesuis to pigs, Salmonella Dublin to cattle, Salmonella Abortusovis to sheep and Salmonella Gallinarum to poultry (2, 3).…”

“…The invasion gene invA, is essential for the entry of the bacterium from the gut lumen into the epithelial cells. It is possibly responsible for the virulence of the bacteria, facilitating their entry into the blood-stream causing bacteraemia (2). The unwarranted use of antimicrobials in large-scale poultry production as veterinary medicine and also as growth promoters is an widening problem causing an increase in antimicrobial resistance in NTS and all other bacteria.…”