Epidemiology of typhoid and paratyphoid fever in Kathmandu: two years study and trends of antimicrobial resistance.

Enteric fever is prevalent in developing countries including Nepal, where it still remains as a major health problem. Appropriate antibiotics are essential for the treatment of typhoid and paratyphoid fever. A prospective study was carried out to characterize the epidemiological features of enteric fever in Kathmandu, Nepal and to analyse the recent trend of antimicrobial resistance pattern of the Salmonella isolated from the cases of enteric fever from different hospitals in Kathmandu during June, 2002 to June, 2004. A total of 1469 Salmonella typhi and Salmonella paratyphi 'A' isolates collected during this period from five different hospital laboratories situated in Kathmandu were studied. The antimicrobial susceptibilities of the isolates towards Ampicillin (10 mcg), Chloramphenicol (30 mcg), Cotrimoxazole (25 mcg), Ciprofloxacin (5 mcg) and Ceftriaxone (5 mcg) were determined by standard disc diffusion technique and Agar dilution technique were used to determine the minimum inhibitory concentration (MIC) for Ampicillin, Ciprofloxacin, Chloramphenicol and Ceftriaxone. All the isolates tested were found to be sensitive to Ceftriaxone and Ciprofloxacin, the most commonly used antibiotic for treatment of enteric fever in Nepal. Of the total isolates studied, 15.5% from 2002, 8% from 2003 and 3.45% from 2004 were found to be multidrug resistant (exhibiting resistance towards Ampicillin, Chloramphenicol and Cotrimoxazole). Of the total multi drug resistant Salmonella isolates, 92% were Salmonella typhi. All the multidrug resistant isolates were also further tested for susceptibilities towards Tetracycline (30 mcg), Nalidixic acid (30 mcg), Streptomycin (10 units), Gentamycin (25 mcg), Azithromycin (15 mcg), Kanamycin (30 mcg), Neomycin (30 mcg). 50% of the multi drug resistant Salmonella typhi were also resistant to Tetracycline. Plasmid analysis revealed that all of the multidrug resistant Salmonella typhi isolates with Tetracycline resistance harbored a large molecular weight (147 Kb) plasmid.

Bacterial enteric pathogens in children with acute dysentery in Thailand: increasing importance of quinolone-resistant Campylobacter.

Current data on pathogen prevalence and drug resistance patterns are important for treatment and vaccine-development strategies. An etiologic study of acute bacterial dysentery was conducted in children up to 12 years of age in 2 major hospitals in and around Bangkok. Stool samples or rectal swabs and clinical data were collected. Standard microbiological methods were used to detect Salmonella, Shigella, Campylobacter, Vibrio, Aeromonas and Plesiomonas. Pathogenic E. coli (ETEC, EIEC, STEC) was identified by digoxigenin-labeled probes. A total of 623 cases were enrolled: median age 11.0 months (range 1 month-12 years). At least one bacterial pathogen was isolated in 55% of cases. Campylobacter was the most common pathogen found (28%), whereas Salmonella, Shigella and ETEC were isolated from 18%, 9% and 6% respectively. EIEC, Vibrio and Plesiomonas were isolated from <1% and no STEC was detected. C. jejuni serotypes 36, 4 and 11 were the most common. The mean age of cases with Campylobacter was significantly lower than with Shigella (17.9 vs 52.8 months, p<0.001). Clinical presentations of Campylobacter and Shigella infections were compared: fever (28% vs 37%), abdominal colic (62% vs 80%, p<0.05), vomiting (38% vs 70%, p<0.001) and bloody stools (52% vs 48%). The Campylobacter isolates (80% C. jejuni, 20% C. coli) were 90% resistant to ciprofloxacin but sensitive to macrolides. All the Shigella isolates (70% S. sonnei) were sensitive to quinolones. Our study illustrates the increasing importance of quinolone-resistant Campylobacter and the decline of Shigella in the etiology of dysentery in Thailand. The clinical presentation of campylobacteriosis is similar to that of shigellosis, except that the patients may be younger and there may be less association with colic and vomiting; having fecal leukocytes will be >10/HPF. The use of macrolide antibiotics rather than quinolones would be reasonable in children <24 months of age; fluoroquinolones will be ineffective in at least half of culture-positive cases.