Molecular characteristics of Shigella spp. isolated from patients with diarrhoea in a new industrialized area of Thailand.

In this study, we used plasmid profile analysis, XbaI macrorestriction with pulsed-field gel electrophoresis (PFGE), and PCR of the ipaH gene, to study the molecular characteristics of 183 Shigella spp. isolated during May 2000 to April 2003 from rectal swabs of patients with watery and/or bloody diarrhoea in a new industrialized area of Thailand. Among the 183 isolates, 167 were S. sonnei and 16 were S. flexneri. For plasmid profile analysis, the 183 isolates revealed 16 different plasmid patterns, designated patterns A to P. The sizes of the plasmid bands were: 6, 5.5, 5, 4.5, 4, 3.25, 2.75, 2.5, 2, 1.75, 1.5 and/or 1.25 kb. The frequency of each plasmid band was 4.5 kb (165 isolates), 3.25 kb (161 isolates), 5.5 kb (129 isolates), 1.75 kb (121 isolates), 1.5 kb (35 isolates), 5 kb (21 isolates), 2 kb (16 isolates), 2.75 kb (12 isolates), 1.25 kb (9 isolates), and 6 kb (8 isolates). PFGE analysis revealed 45 different XbaI macrorestricted DNA banding patterns which could be grouped into 11 groups. All the isolates gave PCR amplicons of the ipaH gene. Plasmid profile analysis and PFGE are powerful tools for differentiation of the Shigella spp. This study provides important data on the molecular characteristics of Shigella isolates in Thailand, which could be useful as an epidemiological baseline for identifying relationships with strains that may emerge in the future.

Shigellosis remains an important problem in children less than 5 years of age in Thailand.

This is a review of existing data on the burden of shigellosis in Thailand to determine trends, vulnerable groups, predominant species and serotypes, and antimicrobial resistance patterns. Diarrhoea and dysentery morbidity and mortality data from 1991 to 1999 was collected from the routine surveillance system and demographic data from the government census. International and local literature published between 1988 and 2000 was systematically reviewed. Based on the routine surveillance system, the annual incidence of bacillary dysentery decreased from 1.3 to 0.2/10,000 persons per year. The remaining burden is highest in children <5 years of age at 2.7/10,000 persons per year. In comparison, a prospective study utilizing active surveillance found an incidence in children <5 years of age that was more than 100-fold higher at 640/10,000 persons per year. Despite the decrease in morbidity and mortality based on routinely collected data, shigellosis remains an important problem in children <5 years of age in Thailand.

Significant increase in antibiotic resistance of Salmonella isolates from human beings and chicken meat in Thailand.

A total of 1715 Salmonella strains, including 600 S. enteritidis, 290 S.derby, 257 S. Weltevreden, 122 S. 1,4,5,12:i:-, 235 S. anatum, and 211 S. typhimurium, originating from 1308 human beings and 407 frozen chicken meat specimens collected in 1993 and 1994 were tested for antibiotic resistance. The disk diffusion method was used with nine disks of chloramphenicol, ceftriaxone, amikacin, kanamycin, ampicillin, sulfamethoxazole plus trimethoprim, nalidixic acid, gentamicin and ofloxacin. The resistance rates of human beings isolates in 1994 to ceftriaxone, amikacin and kanamycin were, respectively, 10.7%, 8.6%, 17.8% in S. enteritidis; 23.1%, 17.3% 33.0% in S. derby; 30.9%, 40.2%, 60.4% in S. weltevreden; 16.1%, 17.7%, 70.9% in S.1, 4, 5, 12:i:-; 25.7%, 21.6%, 24.7% in S. anatum; 18.9%, 15.7%, 37.8% in S. typhimurium, while those isolates in 1993 to the same three antibiotics were, respectively, 1.8%, 0.6%, 3.7% in S. enteritidis; 0.8%, 0%, 9.1% in S.derby; 1.8%, 2.7%, 10.8% in S. weltevreden; 3.8%, 0%, 23.0% in S.1, 4, 5, 12:i:-; 2.2%, 2.2%, 6.7% in S. anatum; 4.5%, 1.5%, 10.6% in S. typhimurium. It was shown that the resistance rates in 1994 were significantly higher than those in 1993. All isolates were susceptible to ofloxacin with the exception of one isolate.