Subject(s)
Anti-Bacterial Agents/therapeutic use , Drug Resistance, Bacterial/genetics , Fluoroquinolones/therapeutic use , Salmonella typhi/genetics , Typhoid Fever/epidemiology , Typhoid Fever/microbiology , Disk Diffusion Antimicrobial Tests , Humans , India/epidemiology , Microbial Sensitivity Tests , Typhoid Fever/drug therapyABSTRACT
BACKGROUND & OBJECTIVES: Shigellosis is known to be a major cause of acute childhood diarrhoea in Andaman & Nicobar Islands, India. Rapid emergence of antibiotic resistance warrants continuous monitoring of sensitivity pattern of bacterial isolates. We report here the salient findings of an ongoing study on shigellosis in Andaman Islands, India, with regards to change in drug resistance pattern during the past one decade. METHOD: During 2006-2009, stools samples from 412 paediatric diarrhoea patients were collected and processed for isolation and identification of Shigella spp. Susceptibility to 22 antimicrobial drugs was tested and MICs were determined for 3 rd generation cephalosporins, quinolones, amoxicillin-clavulanic acid combination and gentamicin. Drug susceptibility pattern of these isolates were compared with that of 33 isolates obtained during 2000-2002. RESULTS: Shigella isolates were recovered from 50 of 412 stool samples processed. Resistance to ampicillin, nalidixic acid, tetracycline and ciprofloxacin was observed in 100, 96, 94 and 82 per cent of the isolates, respectively. The frequency of resistance to these drugs was significantly (P<0.001) higher than that observed during 2000-2002. Resistance to seven drugs was observed in 2000-2002, whereas resistance to 21 drugs was seen during 2006-2009. The number of drug resistance pattern increased from 13 in 2000-2002 to 43 in 2006-2009. Resistance to newer generation fluoroquinolones, 3 rd generation cephalosporins and augmentin, which was not observed during 2000-2002, appeared during 2006-2009. INTERPRETATION & CONCLUSIONS: The frequency of resistance among Shigella isolates has increased substantially between 2000-2002 and 2006-2009 and the spectrum of resistance has widened. At present, the option for antimicrobial therapy in shigellosis in Andaman is limited to a small number of drugs. Continuous local monitoring of resistance patterns is necessary for the appropriate selection of empirical antimicrobial therapy.
Subject(s)
Dysentery, Bacillary/microbiology , Shigella/drug effects , Adolescent , Anti-Bacterial Agents/pharmacology , Child , Child, Preschool , Drug Resistance, Multiple, Bacterial , Dysentery, Bacillary/drug therapy , Dysentery, Bacillary/epidemiology , Humans , India/epidemiology , Infant , Microbial Sensitivity Tests , Shigella/isolation & purificationABSTRACT
Shigellosis is a major cause of diarrheal diseases among children in Andaman & Nicobar Islands, India, which have a population of 350,000 people, including settlers from mainland India and 6 indigenous tribes. From the last one-and-half decade, we have been monitoring the species distribution and emergence of antibiotic resistance among the isolates of Shigella. The circulating Shigella strains have been found rapidly acquiring resistance to a wide spectrum of antibiotics. The recent data indicate that a significant proportion of Shigella isolates have been resistant to newer generation of cephalosporins, which are used as an alternative of quinolones to treat the patients with shigellosis. In this communication, we report the antibiotic-resistant pattern of Shigella isolates that are recently isolated from these islands. From January 2008 to December 2009, 311 stool samples were processed and 44 (14%) Shigella isolates were recovered. Out of these 44 Shigella isolates, 6 (14%) were found to be resistant to all the three third-generation cephalosporins tested. The minimum inhibitory concentrations of the resistant isolates were all above the breakpoint for reduced susceptibility as per the Clinical and Laboratory Standards Institute guidelines. All of the cephalosporin-resistant Shigella strains were confirmed to produce extended-spectrum ß-lactamases. By analyzing trends in the resistance patterns of the various Shigella species, we found that Shigella dysenteriae (40%) is currently more resistant, followed by Shigella flexneri (14%), than the other Shigella species in these islands of India, especially to the third-generation cephalosporins. The acquisition of resistance by enteric pathogens to the increasing number of antibacterial drugs is becoming a grave concern, particularly in developing countries where shigellosis is of a common occurrence.
