The relatedness of group A streptococcal (GAS) strains isolated from 35 Canadian patients with invasive disease of different severity was investigated by a variety of molecular methods. All patients were infected with M1T1 strains and, based on clinical criteria, were classified as severe (n ‫؍‬ 21) and nonsevere (n ‫؍‬ 14) invasive GAS infection cases. All the M1 strains studied had the emm1.0 allele and the same streptococcal pyrogenic exotoxin (Spe) genotype, speA ؉ speB ؉ speC speF ؉ speG ؉ speH smeZ ؉ ssa. All isolates had the same speA allotype, speA2. The randomly amplified polymorphic DNA banding pattern with two different primers was identical for all strains, and pulsed field gel electrophoresis analysis showed that 33 and 30 isolates had identical banding patterns after DNA digestion with SfiI or SmaI, respectively; the nonidentical isolates differed from the main pattern by only one band. A relatively high degree of polymorphism in specific regions of the sic gene was observed among isolates; however, this polymorphism was not associated with disease severity. Likewise, although the phenotypic expression of SpeA, SpeB, and SpeF proteins varied among the M1T1 isolates, there was no correlation between the amount of Spe expressed and disease severity. Importantly, mitogenic and cytokine responses induced by partially purified bacterial culture supernatants containing a mixture of expressed superantigens were very similar for isolates from severe and nonsevere cases (P > 0.1). Together, the data indicate that highly related invasive M1T1 isolates, some indistinguishable, can cause disease of varying severity in different individuals. These findings underscore the contribution of host factors to the outcome of invasive GAS infections.Group A streptococci (GAS) are responsible for a variety of human diseases ranging from simple pharyngitis to highly severe infections, such as necrotizing fasciitis (NF) and streptococcal toxic shock syndrome (STSS) (16). Since the late 1980s, a marked increase in the incidence and severity of invasive infections has been reported in the United States, Canada, Japan, and many regions of Europe (11,13,16,17,20,22,37). Whether this dramatic rise in the incidence of invasive GAS infections resulted from changes in virulence properties of the bacteria and/or alterations of host protective immunity against specific strains or specific virulence factors remains an area of intense investigation.Among the many virulence factors produced by GAS, the M protein and the streptococcal pyrogenic exotoxins (Spes) are considered important virulence factors in the pathogenesis of invasive GAS infections. The Spes belong to the superantigen (SAg) family and thus can induce massive secretion of inflammatory cytokines, such as gamma interferon (IFN-␥), interleukin-1 (IL-1), and tumor necrosis factor ␣. Overproduction of these cytokines can lead to tissue damage, organ failure, and shock (reviewed by Kotb [15]).GAS are classified by their surface M protein type (4, 10). To date, more than 100 d...

The use of Fourier transform near-infrared (FT-NIR) spectroscopy and multivariate pattern recognition techniques for the rapid detection and identification of bacterial contamination in liquids was evaluated. The complex biochemical composition of bacteria yields FT-NIR vibrational transitions (overtone and combination bands) that can be used for classification and identification. Bacterial suspensions (Escherichia coli HB101, E. coli ATCC 43888, E. coli 1224, Bacillus amyloliquifaciens, Pseudomonas aeruginosa, Bacillus cereus, and Listeria innocua) were filtered to harvest the cells and eliminate the matrix, which has a strong NIR signal. FT-NIR measurements were done using a diffuse reflection-integrating sphere. Principal component analysis showed tight clustering of the bacterial strains at the information-rich spectral region of 6000-4000 cm(-1). The method reproducibly distinguished between different E. coli isolates and conclusively identified the relationship between a new isolate and one of the test species. This methodology may allow for the rapid assessment of potential bacterial contamination in liquids with minimal sample preparation.

Pulsed-field gel electrophoresis (PFGE) was performed on 180 isolates of Vibrio cholerae serogroup 01 representing 6 different multilocus enzyme electrophoresis (MEE) types and 27 rRNA restriction fragment length polymorphism types (ribotypes). Isolates were digested with the restriction enzyme NotI and were separated into 63 patterns on the basis of differences in band arrangements. In general, strains which were different by MEE or ribotyping also had different PFGE patterns. PFGE identified individual strains within a single MEE type or ribotype; isolates with one PFGE pattern were less frequently distinguished by ribotyping. All V. cholerae 01 isolates tested from the Latin American epidemic were indistinguishable by their MEE, ribotype, or PFGE patterns. PFGE could further distinguish strains of this same ribotype isolated in Africa, Europe, the South Pacific, or Southeast Asia. Although both MEE and PFGE could identify the strain from the Latin American epidemic, PFGE was more rapid and less labor intensive. PFGE also distinguished nontoxigenic isolates endemic to the U.S. Gulf Coast from unrelated nontoxigenic isolates. In the present study PFGE was more discriminating than other previously described subtyping assays for V. cholerae 01 and appears to be a useful epidemiologic tool.

Vibrio chokrae 01, serotype Inaba, biotype El Tor, was recovered from nonpotable (ballast, bilge, and sewage) water from five cargo ships docked in ports of the U.S. Gulf of Mexico. Four of these ships had taken on ballast water in cholera-infected countries; the fifth took on ballast in a noninfected country. Isolates examined by pulsed-field gel electrophoresis were indistinguishable from the Latin American epidemic strain, C6707; however, they differed significantly from the endemic Gulf Coast strain (VRL 1984), the sixth-pandemic strain (569-B), and a V. chokrae non-Ol strain isolated from a ship arriving from a foreign port. On the basis of our findings, the Food and Drug Administration recommended that the U.S. Coast Guard issue an advisory to shipping agents and captains requesting that ballast waters be exchanged on the high seas before entry of ships into U.S. ports.