Comparison of Salmonella typhi and Paratyphi A Occurrence in a Tertiary Care Hospital

New Insights on the Early Interaction Between Typhoid and Non-typhoid Salmonella Serovars and the Host Cells

Salmonella enterica is a common source of food and water-borne infections, causing a wide range of clinical ailments in both human and animal hosts. Immunity to Salmonella involves an interplay between different immune responses, which are rapidly initiated to control bacterial burden. However, Salmonella has developed several strategies to evade and modulate the host immune responses. In this sense, the main knowledge about the pathogenicity of this bacterium has been obtained by the study of mouse models with non-typhoidal serovars. However, this knowledge is not representative of all the pathologies caused by non-typhoidal serovars in the human. Here we review the most important features of typhoidal and non-typhoidal serovars and the diseases they cause in the human host, describing the virulence mechanisms used by these pathogens that have been identified in different models of infection.

Prevalence of Enteric Fever Pathogens Isolated from Blood Culture at a Tertiary Care Centre

INTRODUCTION

Typhoid fever and paratyphoid fever commonly called as enteric fever is a life-threatening illness caused by Salmonella serotype Typhi and Salmonella serotype Paratyphi, respectively. It is a major public health issue in underdeveloped and developing countries. The aim of the study is to find out the prevalence of enteric fever pathogens in blood culture of patients attending a tertiary care centre.

METHODS

A descriptive cross-sectional study was conducted in 3483 blood samples of patients attending a tertiary care centre, with the history and symptoms suspicious of enteric fever during one year period from mid-September 2019 to mid-September 2020 after ethical approval from the institutional review committee. Isolates were identified by standard microbiological methods and tested for in vitro antibiotic susceptibility by modified kirby-bauer disc diffusion method. The obtained data was entered and analyzed in WHONET 5.6 program, point estimate at 95% was calculated along with frequency and proportion for binary data.

RESULTS

In our study, enteric fever pathogens were isolated from 18 (0.51%) blood samples. Out of which, Salmonella Paratyphi A was isolated from 10 (8.19%) and Salmonella Typhi was isolated from 8 (6.55%) blood samples. Other serotypes were not isolated. Antimicrobial susceptibility test showed that salmonella species that was isolated were sensitive to most of the drugs.

CONCLUSIONS

Prevalence of enteric fever pathogens was lesser compared to other studies. Varying degrees of antibiotic resistance among isolated enteric fever pathogens necessitates continuous surveillance of the susceptibility patterns. Prudent use of antimicrobials, active infection control practices and stringent antibiotic policy should be implemented to prevent emergence of antibiotic resistance and future outbreaks.

Antimicrobial Resistance Surveillance in Typhoidal Salmonella in Ahmedabad in an Era of Global Antimicrobial Resistance Surveillance Systems

Introduction:

India possibly carries the highest burden of antimicrobial resistant typhoidal salmonellae in the world. We report on the health-care ecosystem that produces data on antimicrobial resistance (AMR) testing and the resistance patterns of typhoidal Salmonella isolates in the city of Ahmedabad.

Materials and Methods:

Through municipality records and internet searches, we identified 1696 private and 83 public laboratories in the city; 4 medical colleges, 4 health-care institution attached laboratories, and 4 corporate laboratories (CLs) were performing culture and antibiotic sensitivity testing (AST), but only 2 medical colleges and 1 CL shared their data with us. There was considerable variation in culturing and sensitivity testing methodology across laboratories.

Results:

Out of 51,260 blood cultures, Salmonella isolates were detected in only 146 (0.28%). AST was conducted on 124 isolates, of which 67 (54%) were found resistant. Multidrug resistance was absent. Concurrent resistance to more than one antibiotic was very high, 88%, among the 67 resistant isolates. Ciprofloxacin resistance varied widely between the private and public sector laboratories. Notably, isolates from the private sector laboratory showed complete resistance to azithromycin.

Conclusions:

High resistance to ciprofloxacin and azithromycin observed in Ahmedabad may be due to the increased use of these two antibiotics in the public and private sectors, respectively. The need of the hour is to identify a representative sample of laboratories from both the public and the private sectors and encourage them to participate in the national AMR surveillance network.