Antibiogram of S. enterica serovar Typhi and S. enterica serovar Paratyphi A: a multi-centre study from India.

BACKGROUND Enteric fever continues to be a public health problem in many countries including India. Emergence of the multidrug resistant strains of S. enterica serovar Typhi may render treatment with antibiotics ineffective. A multi-centre surveillance study was, therefore, conducted in India to monitor the time trends in antibiotic susceptibility patterns of S. enterica serovar Typhi and S. enterica serovar Paratyphi A in India. METHODS All S. enterica serovar Typhi and S. enterica serovar Paratyphi A strains isolated from January 2008 to December 2010 in the 15 participating centres were included in the study. Each centre compiled their data in a predefined template which included data of the antimicrobial susceptibility pattern, location of the patient and specimen type. The data in the submitted templates was collated and analysed using a common protocol. RESULTS A total of 3275 isolates of Salmonellae causing enteric fever were included in the study. There were 2511 S. enterica serovar Typhi and 764 S. enterica serovar Paratyphi A strains during the three-year study period. Resistance to nalidixic acid was seen in 83% of the S. enterica serovar Typhi and 93% of S. enterica serovar Paratyphi A strains. Majority of the strains were susceptible to third generation cephalosporins. CONCLUSIONS Enteric fever in India is caused by S. enterica serovar Typhi and S. enterica serovar Paratyphi A. Nalidixic acid resistance is high among both S. enterica serovar Typhi and S. enterica serovar Paratyphi A. Susceptibility to ampicillin, chloramphenicol and cotrimoxazole is high. Third generation cephalosporins continue to remain susceptible.