Salmonella Case Study

The aim of the study was to find out the occurrence and diversity of multi drug resistant of salmonella enterica serovar typhi in and around Chennai, India. We studied the drug resistance of different microbes from clinical isolates based on the phenotypic character. The morphological characteristics of bacteria were observed through culture characteristics by carrying out gram staining techniques while the biochemical characteristics of bacteria were carried out by biochemical test. A total of 2423 samples were collected from suspected patients visiting different hospitals, primary health care center, and tertiary care hospitals at in and around Chennai. For morphological identification, samples of clinical isolates were analyzed by blood

Salmonella typhi divided into four biotypes - I, II, III, IV based on the fermentation of D– xylose and L– arabinose7. Biotype I is the most common among the four biotypes8.

Serological characterization (Agglutination)

Serological characterization (Agglutination) was carried out as described by Hendriksen and Larsen9 and with some modification. Loopful of culture was placed at four places on slide and the following antisera were added to them. O9, O12, Vi, Hd. Mixed gently for two minutes and observed for positive and negative reaction. Mixed Poly O was placed on other slide and added with one drop of culture to serve as a positive and saline was placed on other side of slide to serve as a Negative Control.

Phage

105 isolates were further subjected to antibiogram resistogram pattern using disc diffusion susceptibility test. Commercially available 11 antibiotics were tested based up on the Kirby-Bauer methods and the percentage of resistance to antibiotics was found Ampicillin (13%), Cephotaxime (5%), Tetracycline (40%), Cefuroxime (7%), Chloramphenicol (1%), Ciprofloxacin (85%), Nalidixic acid (94%), Streptomycin (10%), Trimethoprim (10%), Gentamycin (4%), and Kanamycin (10%). From these observations, it was noticed that the percentage of MDR strains sensitive to Chloramphenicol 98% and Cefuroxime 92% respectively. The total percentage of MDR strains were 5% from the total 2423 samples were observed. The prevalence of Salmonella enterica typhi was observed more at Chennai outer (10%) and low at south Chennai (3%) where the development of industries in outer chennai and less awareness of peoples were the percentage of positive is high which shown in Table 1. Further it was also observed that the people belonging to the age groupof 01 to 10 years are more affected by the Salmonella enterica typhi. The other age groups are listed in Table 2. We confirmed that all the isolates of Salmonella enterica typhi belonging to Biotype-1 by using of D-Xylose and L-Arabinose and it was showed in Table 3. On the basis of serological characterization we confirmed 100%