204 TRANSACTIONS OF THE ROYAL SOCIETY OF
An outbreak Pondicherry
of typhoid
TROPICAL MEDICINE ANDHYGIENE (1992)86, 204-205
due to multidrug
resistant
Salmonella
R. Sambasiva Rae*, Satish Kumar Amamath and S. Sujatha Department Postgraduate Medical Education and Research, Pondichery-605 006, India
typhiin
of Microbiology, Jawaharlal Institute of
Abstract An outbreak of typhoid due to multi-drug resistant Salmonella typhi is reported from Pondicherry, India. While the averageprevalenceof drug resistant strains in 1980-1988had been 11.7%, it increasedto 52% in 1989-1990. The majority of strains (80.8%) were resistant to chloramphenicol, streptomycin, tetracycline and ampicillin; 40% were resistant to co-trimoxazole. Minimum inhibitory concentrations to 8 antibiotics for 17 representativestrains were more than lo-fold greater than those of 13 sensitivestrains. The multi-resistancewas shown to be plasmid mediated in direct conjugation experimentsand the strains belongedto Viphagetype 0, biotype II.. Introduction In India, drug resistanceamong SaZmoneZlatyphi has been reported since 1960(AGARWAL, 1962; MURTI et al., 1962). Calicut in Kerala state experiencedthe first outbreak of typhoid due to multiple drug resistant S. typhi (PANICKER & VIMLA, 1972). Subsequently,sporadicisolations of drug resistant S. typhi were reported from many places (PARAMAsIVANet al., 1977; R.40 et al., 1981; SRIDHARet al., 1983)with localized outbreaks m Ernakulam and Chandigarh. Since 1976, multi-resistant S. typhi have spread all over south India carrying resistanceto chloramphenicol and tetracycline (K. B. Sharma, unpublished observationst). We report here a major, continuing outbreak of drug resistant typhoid in Pondicherry. Materials and Methods Bacteriology. Blood and stool cultures for the isolation of S. typht, their identification by biochemical and slide agglutination tests, and drug susceptibility testing by the Kirby-Bauer method were performed according to standardmethods (COWAN& STEEL,1965;FINEGOLD& BARNO, 1986). The strains were preservedin semi-solid agar for further tests. Phagetyping was done at the National Reference Centre, Lady Hardinge Medical College, New Delhi. Minimum inhibitory concentration (MIC). MICs for 8 antibiotics (ampicillin, chloramphenicol, tetracycline, streptomycin, trimethoprim, sulphamethoxazole, furazolidone and gentamycin) were determined for 30 strains using the agar dilution method; 17 strains were resistant and 13were sensitive. Conjugation experiments. Direct conjugation transfer experiments were carried out using Escherichia coli K12 F-Lac+Nal’ as recipient, as recommendedby the World Health Organization (WHO, 1978). Results and Discussion During 1980-1988, 88 chloramphenicol-resistant strains were identified among 754 isolates of S. typhi; their proportion ranged from 7% to 16%, with a mean of 11.7%. However, during 1990, their incidence reached epidemic proportions (Table 1). An increasein isolation of drug-resistant strains was noticed after November 1989, and by March 1990 it had become clear that we were experiencing an unprecedented outbreak of typhoid. During this period, 48.7% of the isolates(18/37) were resistant to drugs, compared with 10% (3130)isolated in the corresponding period from November 1988 to March 1989. By the end of 199q, the proportion had risen to 57% (52/91), significantly higher than in the previous years (11.7% vs 57%, P25.0 12.5 200.0 8.0