Indian Journal of Pathology and Microbiology

: 2010  |  Volume : 53  |  Issue : 2  |  Page : 389-

Ceftriaxone resistance in Salmonella Typhi - Myth or a reality!

E Rajni Sabharwal 
 Dr Lal Path Labs, 54, Hanuman Road, New Delhi - 110 001, India

Correspondence Address:
E Rajni Sabharwal
D-22 Rose Apartments, Sec 14- Extension, Rohini, Delhi-110 085

How to cite this article:
Sabharwal E R. Ceftriaxone resistance in Salmonella Typhi - Myth or a reality!.Indian J Pathol Microbiol 2010;53:389-389

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Sabharwal E R. Ceftriaxone resistance in Salmonella Typhi - Myth or a reality!. Indian J Pathol Microbiol [serial online] 2010 [cited 2021 Sep 19 ];53:389-389
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Typhoid fever is a multisystem febrile disease caused primarily by Salmonella enterica serovar Typhi. It is recognized as a major cause of morbidity, with over 21.6 million cases, and an estimated 216500 deaths annually worldwide. [1] At present the disease is known to have endemic proportions in India. [1] Multi-drug resistant Salmonella Typhi (MDRST) is defined as strain resistant to all first line antibiotics i.e. chloramphenicol, ampicillin, and cotrimoxazole. Increased isolation rates of MDRST throughout India have been well documented since 1990. [2] Given the variation in the susceptibility patterns reported for Salmonella enterica, it is important to constantly monitor its susceptibility so as to provide suitable guidelines for treatment and formulation of vaccination policies. The present study was therefore designed to study the antibiotic susceptibility pattern among Salmonella enterica serovar Typhi isolates obtained from blood samples at the Department of Microbiology, in a laboratory in New Delhi.

Eighty three clinical isolates of Salmonella Typhi isolated from 2224 blood culture specimens received in the laboratory during the two-month period from August to September, 2008, were included in the study. The laboratory has an automated system of bacterial identification and susceptibility testing by BioMerieux. For identification of the isolates, rapid ID32 E strips are used. The standardized system for identification of Enterobacteriaceae within four hours is use of 32 miniaturized enzymatic tests as well as a specific database. For antibiotic susceptibility testing, all isolates were tested using Rapid ATB E4 strips. These enable the susceptibility of enterobacteria to antibiotics after 41/2 -5 hours of incubation. The panel of antibiotics tested included: cefalothin, cefazolin, cefuroxime, cefamandole cefotaxime, ceftriaxone, ceftazidime, cefepime, ampicillin, amoxycillin, amoxyclav, ofloxacin, ciprofloxacin, levofloxacin, gentamicin, amikacin, netilmicin, tobramycin, pipercillin, ticarcillin, chloramphenicol and cotrimoxazole. The use of miniAPI system, provided by BioMerieux is obligatory for reading these strips. Cefixime, being an orally active third generation cephalosporin, thereby allowing better compliance, was tested manually for sensitivity by Kirby Bauer disc diffusion method. Quality control was done using standard ATCC strains once in a week.

Resistance to chloramphenicol and cotrimoxazole was seen in 14 and 10% isolates respectively. All the isolates were resistant to ampicillin and amoxicillin (100% resistance), however, only 2.4% were resistant to Amoxyclav. 20-30% isolates exhibited resistance to fluoroquinolones, with levofloxacin appearing most effective followed by ciprofloxacin. A mere 4-5% isolates were resistant to the aminoglycosides tested. (As per CLSI guidelines aminoglycoside resistance is not reported.) Third generation cephalosporin resistance was not seen in any isolate. This is in concordance with a contemporary study which reports ceftriaxone resistance as nil. [3] Ceftriaxone and Cefixime, therefore, are important additions to our armamarium against typhoid fever . Of the various third generation cephalosporins available in the market, cefixime is orally active and can easily be administered to ambulatory patients who do not require hospitalization as well as children (unlike fluoroquinolones which are not considered safe for children). In fact, because of the growing popularity of this drug amongst the clinicians, due to its oral administration, the laboratory had to initiate manual testing by disc diffusion for this particular drug as it was not covered in the E4 strip.

High degree of resistance to other first line drugs probably reflects their overuse or irrational use in the treatment of typhoid as well as in other unrelated infections. Though cases of Salmonella Typhi resistant to ceftriaxone have already been reported from Bangladesh, Pakistan and Philippines this menace has not reached India. [4],[5],[6] If this trend of emerging cephalosporin resistance is peculiar to the developing nations, we need to be on a constant guard. As of now, a conjoint effort on the part of doctors, patients and government is needed to carry out a continued surveillance of resistant strains and judicious selection and use of antibiotics.


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