Emergence of fluoroquinolone resistance in Shigella isolated from Andaman & Nicobar Islands, India.

The Andaman & Nicobar Islands, situated in the Bay of Bengal, is an Union Territory of India. Health care in these islands (population of about 3 50 000) is almost entirely provided by the Government. G.B. Pant Hospital, located at Port Blair, is the only referral hospital in the islands. Bacteriological surveillance carried out by the RMRC, Port Blair at this hospital, has identified shigellosis as endemic and a major cause of acute diarrhoea in children1,2. Like in mainland India and most of the other developing countries Shigella flexneri 2a has been the commonest isolate with the proportion of different species and serotypes of Shigella isolated showing considerable variation. For example, S. dysenteriae 1 was dominant during an outbreak during 1995-96 while S. sonnei and S. flexneri appeared as the commonest isolate in alternate years during 2000-20041,3. Antibiotic resistance pattern also showed variations. As in all developing countries, the choice of limited number of effective antimicrobials for empirical treatment of suspected infections caused by rapid emergence of multi-drug resistant shigellae has been a problem to clinicians in these islands. The ampicillin (AMP)-co-trimoxazole (CoT) resistant strain of S. dysenteriae type 1 that was widespread in mainland India during1980s, was first observed in the Andaman islands in 19864 which prompted clinicians to discontinue the use of these antimicrobials and by early 1990s nalidixic acid (NAL) became the drug of choice in treatment. By 1994, when routine surveillance started, all shigellae isolated became resistant to AMP and 80.6 per cent to CoT1. NAL resistance (15.1%) was first observed in S. dysenteriae 1 during an outbreak of diarrhoea in 19952 but it remained confined to S. dysenteriae and occasional S. flexneri isolated from sporadic cases till 1999-2000. NAL continued to be the drug Emergence of fluoroquinolone resistance in Shigella isolated from Andaman & Nicobar Islands, India