Diagnostic approach to acute diarrheal illness in a military population on training exercises in Thailand, a region of campylobacter hyperendemicity.

High rates of Campylobacter fluoroquinolone resistance highlight the need to evaluate diagnostic strategies that can be used to assist with clinical management. Diagnostic tests were evaluated with U.S. soldiers presenting with acute diarrhea during deployment in Thailand. The results of bedside and field laboratory diagnostic tests were compared to stool microbiology findings for 182 enrolled patients. Campylobacter jejuni was isolated from 62% of the cases. Clinical and laboratory findings at the time of presentation were evaluated to determine their impact on the posttest probability, defined as the likelihood of a diagnosis of Campylobacter infection. Clinical findings, the results of tests for inflammation (stool occult blood testing [Hemoccult], fecal leukocytes, fecal lactoferrin, plasma C-reactive protein), and the numbers of Campylobacter-specific antibody-secreting cells in peripheral blood failed to increase the posttest probability above 90% in this setting of Campylobacter hyperendemicity when these findings were present. Positive results by a Campylobacter-specific commercial enzyme immunoassay (EIA) and, less so, a research PCR were strong positive predictors. The negative predictive value for ruling out Campylobacter infection, defined as a posttest probability of less than 10%, was similarly observed with these Campylobacter-specific stool-based tests as well the fecal leukocyte test. Compared to the other tests evaluated, the Campylobacter EIA is a sensitive and specific rapid diagnostic test that may assist with diagnostic evaluation, with consideration of the epidemiological setting, logistics, and cost.

Traveler's diarrhea in Thailand: randomized, double-blind trial comparing single-dose and 3-day azithromycin-based regimens with a 3-day levofloxacin regimen.

BACKGROUND: Traveler's diarrhea in Thailand is frequently caused by Campylobacter jejuni. Rates of fluoroquinolone (FQ) resistance in Campylobacter organisms have exceeded 85% in recent years, and reduced fluoroquinolone efficacy has been observed. METHODS: Azithromycin regimens were evaluated in a randomized, double-blind trial of azithromycin, given as a single 1-g dose or a 3-day regimen (500 mg daily), versus a 3-day regimen of levofloxacin (500 mg daily) in military field clinics in Thailand. Outcomes included clinical end points (time to the last unformed stool [TLUS] and cure rates) and microbiological end points (pathogen eradication). RESULTS: A total of 156 patients with acute diarrhea were enrolled in the trial. Campylobacter organisms predominated (in 64% of patients), with levofloxacin resistance noted in 50% of Campylobacter organisms and with no azithromycin resistance noted. The cure rate at 72 h after treatment initiation was highest (96%) with single-dose azithromycin, compared with the cure rates of 85% noted with 3-day azithromycin and 71% noted with levofloxacin (P=.002). Single-dose azithromycin was also associated with the shortest median TLUS (35 h; P=.03, by log-rank test). Levofloxacin's efficacy was inferior to azithromycin's efficacy, except in patients with no pathogen identified during the first 24 h of treatment or in patients with levofloxacin-susceptible Campylobacter isolates, in whom it appeared to be equal to azithromycin. The rate of microbiological eradication was significantly better with azithromycin-based regimens (96%-100%), compared with levofloxacin (38%) (P=.001); however, this finding was poorly correlated with clinical outcome. A higher rate of posttreatment nausea in the 30 min after receipt of the first dose (14% vs. <6%; P=.06) was observed as a mild, self-limited complaint associated with single-dose azithromycin. CONCLUSIONS: Single-dose azithromycin is recommended for empirical therapy of traveler's diarrhea acquired in Thailand and is a reasonable first-line option for empirical management in general.

Typhoid fever: a massive, single-point source, multidrug-resistant outbreak in Nepal.

BACKGROUND: In the summer of 2002, a total of 5963 cases of typhoid fever were recorded in Bharatpur, Nepal (population, 92,214) during a 7-week period. A team from the Armed Forces Research Institute of Medical Sciences in Bangkok, Thailand, and the CIWEC Travel Medicine Clinic (Kathmandu, Nepal) assisted the Nepal National Public Health Laboratory (Kathmandu, Nepal) in the further investigation of this large, explosive febrile disease outbreak. METHODS: Investigators conducted a thorough epidemiologic and laboratory investigation to assess the size and scope of the outbreak. In addition to subculturing of previously collected samples, blood samples were obtained from 100 febrile patients, and culture and susceptibility testing were done by standard laboratory methods. Pulsed field gel electrophoresis (PFGE) and plasmid analysis were done. RESULTS: The majority of the isolates, including 1 from the municipal water supply, were multidrug resistant. The minimum inhibitory concentrations (MICs) of ciprofloxacin ranged from 0.19 microg/mL to 0.125 microg/mL. With use of PFGE, all isolates, including isolates from the water supply, showed an analytical similarity of 96%-100%. Multidrug-resistant isolates had a plasmid encoding for resistance, and those with resistance to nalidixic acid had a single-point mutation. CONCLUSIONS: To the best of our knowledge, this outbreak is the largest single-point source outbreak of multidrug-resistant typhoid fever yet reported, and it was molecularly traced to the city's single municipal water supply. Isolates were uniformly resistant to nalidixic acid, there was a decrease in their susceptibility as measured by MIC of fluoroquinolones, and 90% of isolates obtained were resistant to >1 antibiotic.

Re-evaluation of commercially available enzyme-linked immunosorbent assay for the detection of Giardia lamblia and Cryptosporidium spp from stool specimens.

This study aimed to detect Giardia lamblia and Cryptosporidium spp infection from stool specimens. A total of 345 stool specimens were examined by microscopy (both direct smear and formalin concentration) and EIA techniques (ProSpecT Microplate Assay) for G. lamblia and Cryptosporidium spp. Of 73 tests positive for G. lamblia, 41(56.2%) were positive by microscopy, and 71(97.3%) were positive by EIA. Of 16 tests positive for Cryptosporidium spp, 5 (31.3%) were positive by microscopy, and 16(100%) were positive by EIA technique. The results demonstrate that this EIA method is quick, simple, and more sensitive than the microscopy method and should be used for the detection of G. lamblia and Cryptosporidium spp where the prevalence of these protozoan parasites is a public health problem.

Comparative antibiotic resistance of diarrheal pathogens from Vietnam and Thailand, 1996-1999.

Antimicrobial resistance rates for shigella, campylobacter, nontyphoidal salmonella, and enterotoxigenic Escherichia coli were compared for Vietnam and Thailand from 1996 to 1999. Resistance to trimethoprim-sulfamethoxazole, ampicillin, chloramphenicol, and tetracycline was common. Quinolone resistance remains low in both countries, except among campylobacter and salmonella organisms in Thailand. Nalidixic acid resistance among salmonellae has more than doubled since 1995 (to 21%) in Thailand but is not yet documented in Vietnam. Resistance to quinolones correlated with resistance to azithromycin in both campylobacter and salmonella in Thailand. This report describes the first identification of this correlation and its epidemiologic importance among clinical isolates. These data illustrate the growing magnitude of antibiotic resistance and important differences between countries in Southeast Asia.