We serotyped 44,087 Salmonella isolates from humans and 26,148 from other sources from 1993 through 2002. The most common serovar causing human salmonellosis in Thailand was Salmonella enterica Weltevreden. Serovars causing human infections in Thailand differ from those in other countries and seem to be related to Salmonella serovars in different food products and reservoirs.

We compared 581 Salmonella enterica serotype Schwarzengrund isolates from persons, food, and food animals in Denmark, Thailand, and the United States by antimicrobial drug susceptibility and pulsed-field gel electrophoresis (PFGE) typing. Resistance, including resistance to nalidixic acid, was frequent among isolates from persons and chickens in Thailand, persons in the United States, and food imported from Thailand to Denmark and the United States. A total of 183 PFGE patterns were observed, and 136 (23.4%) isolates had the 3 most common patterns. Seven of 14 isolates from persons in Denmark had patterns found in persons and chicken meat in Thailand; 22 of 390 human isolates from the United States had patterns found in Denmark and Thailand. This study suggests spread of multidrug-resistant S. Schwarzengrund from chickens to persons in Thailand, and from imported Thai food products to persons in Denmark and the United States.

We conducted a retrospective observational study to assess epidemiological trends and risk factors associated with the 10 most common Salmonella serovars isolated from humans in Thailand between 2002 and 2007. A total of 11,656 Salmonella isolates covering all 6 years were included in the study. The top 10 Salmonella serovars identified during the course of this study were Enteritidis, Stanley, Weltevreden, Rissen, I [1],4,[5],12:i:-, Choleraesuis, Anatum, Typhimurium, Corvallis, and Panama, which accounted for 8108 (69.6%) of the isolates. Most isolates were from patients 5 years; S. Choleraesuis was recovered with a higher frequency from patients in Bangkok and the central region, whereas S. Enteritidis was recovered predominantly from patients in the southern region. This study also indicates a shift in prevalence of the most common Salmonella serovars responsible for human infections in Thailand compared to previous studies. Notably, there was an increase in human infections with S. Stanley, S. Corvallis, and S. Choleraesuis, three serovars that have previously been associated with swine, and a decrease in infections due to S. Weltevreden and S. Anatum. The study also revealed differences in the epidemiology among the different serovars, suggesting that serovar-specific interventions are needed. We recommend initiating targeted interventions for the two serovars associated with a high odds ratio for submitted blood samples, S. Enteritidis and S. Choleraesuis. The authors also recommend additional epidemiologic studies to investigate the observed increase in swine associated serovars (S. Stanley, S. Corvallis, and S. Choleraesuis) and determine interventions to reduce the burden of disease from these serovars.

Recently we reported increases in both the number of Salmonella infections due to Salmonella Rissen in Thailand and the isolation of this serovar from pork products in Thailand. The objectives of the present study were to determine the genetic diversity and antimicrobial resistance of Salmonella Rissen isolates recovered from humans, food products, and animals in Denmark and Thailand. Additionally, risk factors due to travel and consumption of specific food products were analyzed and evaluated. A total of 112 Salmonella Rissen isolates were included in this study from Thailand and Denmark. Thai isolates were recovered from humans, uncooked food, and ready-to-eat food. Danish isolates were obtained from humans (with and without a history of travel to Thailand prior to the infection), Danish pig or pork products, imported pig or pork products, turkeys, and animal feed. A total of 63 unique XbaI PFGE patterns were observed. The predominant pattern was shared by 22 strains. Limited antimicrobial resistance was observed in the Danish strains, and a higher degree of resistance was observed in strains originating from Thailand. Virtually all isolates were resistant to tetracycline. The tetA gene was detected in tetracycline-resistant isolates. Statistical analysis and molecular subtyping identified the combination of travel to Thailand and consumption of imported pig or pork products as well consumption of as pig or pork products produced in Denmark as risk factors for Salmonella Rissen infection among the Danish patients. The outcome of this study might be used as a supplement for future Salmonella Rissen investigations and outbreak detection.

In 2006, 3,531 fecal samples were collected from patients with diarrhea in Henan Province, China. A total of 467 (13.2%) Shigella strains were isolated and serotyped. Seventy-one Shigella flexneri strains were characterized by MIC determination, pulsed-field gel electrophoresis (PFGE), and detection of genes encoding cephalosporin resistance. Most infections were caused by S. flexneri variant X [IV:(7),8] (27.6%), S. sonnei (24.2%), and S. flexneri 2a (20.8%). However, large regional differences were observed. Significantly higher odds (2.0) of females compared to males were infected with S. flexneri 2a. Untypeable S. flexneri (−:6) isolates were absent among males, as were untypeable S. flexneri [I:(7),8] isolates among females. Patient ages ranged from 2 months to 82 years, with 231 subjects (49.7%) <5 years of age. Most of the patients were male (62.1% [ n = 290]). Infections peaked in July; week 27 with 38 cases (8.1%). All of the 71 S. flexneri conferred resistance to nalidixic acid; in addition, 21% ( n = 15) and 79% ( n = 56) were high- and low-level resistant to ciprofloxacin, respectively. Six S. flexneri isolates {serotype 2b [II:7,(8)] and 2b [II:(3),4;7,(8)]} harbored the bla _CTX-M-14 or bla _CTX-M-15 gene. A total of 52 unique XbaI PFGE patterns were observed among the 71 S. flexneri isolates with 11 distinct PFGE clusters. This study revealed a high prevalence of shigellosis with geographical differences in the distribution of serotypes in the distribution of serotypes and also differences in comparisons by gender. A high frequency of resistance, including 100% resistance to ciprofloxacin and resistance to extended-spectrum cephalosporins, was observed. We detected several isolates exhibiting the same PFGE type and MIC profile, indicating multiple undetected outbreaks.