In Vitro Effect of New Antibiotics Against Clinical Isolates of Salmonella Typhi.

OBJECTIVE

To determine the in vitrodisk diffusion and MIC patterns of the therapeutic alternatives for Salmonella Typhi.

STUDY DESIGN

Across-sectional study.

PLACE AND DURATION OF STUDY

Armed Forces Institute of Pathology, Rawalpindi, from June 2011 to May 2013.

METHODOLOGY

Clinical samples were collected from suspected cases of Salmonella infections. Culture was obtained on standard media. Suspected Salmonella colonies were tested by API 20E and confirmed by serology. The isolates were tested for resistance to various antibiotics by Kirby-Bauer disc diffusion method. MIC was done on MDR and ciprofloxacin intermediate or resistant cases by E-strips for selected antibiotics.

RESULTS

One hundred and twenty-eight isolates of Salmonella Typhi were recovered from 2230 specimens. Resistance by disk diffusion technique was 72% for ampicillin, 41.2% for cotrimoxazole, 38% for chloramphenicol, 8% for ciprofloxacin, 4.7% for cefpodoxime, 3.5% each for ertapenem aztreonam and moxifloxacin 2.4% for ceftriaxone and 2.3% for doripenem. No resistance was noted for imipenem, cefepime and gatifloxacin. Imipenem MIC90was 0.38 and MIC50 was 0.25. For cefpirome, MIC90was 0.64 and MIC50 was 0.09. For aztreonam, MIC90 was 0.12 and MIC50 was 0.09. For cefpodoxime MIC90 was 0.75 and MIC50 was 0.38. For azithromycin, these values were 16.0 and 7.0; and for tigecycline they were 0.25 and 0.09.

CONCLUSION

Imipenem, azithromycin, tigecycline, aztreonam, cefpodoxime and cefpirome are potential therapeutic agents for resistant Salmonella Typhi infection.