Gastrointestinal infections in children in the Southeast Asia region: emerging issues

Prevalence and antimicrobial resistance of diarrheagenic Escherichia coli and Shigella species associated with acute diarrhea in Tehran, Iran

A study was performed to determine the prevalence and antimicrobial resistance of Shigella species and diarrheagenic Escherichia coli isolates cultured from patients with acute diarrhea in Tehran, Iran. Between May 2003 and May 2005, 1120 diarrheal specimens were collected and assayed for bacterial enteropathogens by conventional and molecular methods. Etiological agents were isolated from 564 (50.3%) specimens, and included 305 (54%) E coli, 157 (27.8%) Shigella species, and 102 (18%) from other genera of bacteria. The predominant E coli was Shiga toxin-producing E coli (105 isolates [34.5%]) and the predominant Shigella serotype was Shigella sonnei (88 isolates [56.1%]). A high rate of antibiotic resistance was observed among E coli, with 40 of 53 (75.5%) Shiga toxin-producing E coli isolates resistant to amoxicillin and tetra-cycline, and eight (5.2%) E coli isolates resistant to more than six antibiotics. Most Shigella isolates were resistant to tetracycline (95%) and trimethoprim-sulfamethoxazole (91.7%), with greatest antibiotic resistance observed among S sonnei (53 of 88 [60.2%] isolates). Antibiotic resistance is widespread in diarrheagenic E coli and Shigella in children with acute diarrhea in Tehran, Iran; hence, updated strategies for appropriate use of antimicrobial agents in Iran are needed.

Treatment of gastrointestinal infections

Studies aimed at improving treatment strategies for patients with acute diarrhea have included the clinical testing of modifications to the standard oral rehydration solution. A malabsorbed carbohydrate has been found to improve resuscitation, probably through the recruitment of colonic absorptive capacity. A reduced osmolarity solution is safe in adults and as effective as the standard solution. For non-nursing infants, increasing the frequency of feeding with reduced volume results in comparable total caloric intake and diminishes the risk of prolonged diarrhea. Increasing resistance of important enteric pathogens to inexpensive and newer antibiotics continues to be a concern. Reports from Asia of decreased Salmonella typhi resistance to chloramphenicol, attributed to restricted antibiotic usage, may indicate a reversal of the usual trend. A strategy to block the action of shiga toxins in the gut through the use of recombinant bacteria has shown promise in a mouse model. A small but well-designed study supported the use of either norfloxacin or amoxicillin-clavulanic acid in the treatment of small bowel overgrowth syndrome. Studies exploring passive immunity strategies for the treatment of Escherichia coli, Cryptosporidium, and Candida infections have reported variable levels of success.