Analysis of 163 putative Shigella isolates from Canada and the USA showed biochemical reactions consistent with Shigella species, although none of the isolates reacted with antiserum raised against any of the well-established or provisional Shigella serotypes. All these isolates, provisionally designated serotype SH108, were positive for the ipaH gene and the invasion-associated locus. All fermented mannitol, were serologically indistinguishable from each other and showed no reaction in antisera prepared against Escherichia coli serotypes O1 to O181. PCR-RFLP analysis of the genes involved in O-antigen synthesis revealed a common pattern among these isolates that was distinct from recognized Shigella serotypes and E. coli. Between 1999 and 2003, isolates from across Canada were submitted to the National Laboratory for Enteric Pathogens for antibiotic susceptibility testing, phage typing and PFGE. These assays revealed heterogeneity among the members of this serotype. Antimicrobial susceptibility testing with seven antibiotics identified six profiles, with 90 % (45/50) of the isolates resistant to four or more antibiotics and 72 % (36/50) resistant to five or more. All isolates were typable using a panel of 16 phages, with 11 different phage types (PTs) represented. The most common PTs found were PT 3 (64 %), PT 6 (10 %) and PT 16 (6 %). Analysis of XbaI-restricted genomic DNA revealed 16 highly related patterns that were not readily distinguishable from those obtained for some other Shigella serotypes. The World Health Organization Collaborating Center for Shigella has added serotype SH108 to the Shigella scheme as S. boydii serotype 20 (serovar nov.). Strain SH108 (isolate 99-4528) is the reference strain for this serotype.

The etiological agent most commonly associated with bacillary dysentery is Shigella. As part of its mandate, the Bacteriology and Enteric Disease Program of Health Canada identifies and serotypes unusual isolates of Shigella received from provincial laboratories of public health. In this report, six unusual isolates from three provinces were analyzed biochemically and serologically using slide and tube agglutinations and molecularly using standard pulsed-filed gel electrophoresis (PFGE), PCR, and PCR-restriction fragment length polymorphism (RFLP) techniques. All six isolates were identical. PFGE analysis grouped these strains; biochemically, they were mannitol negative and consistent with the profile of Shigella. Serologically, these strains produced weak reactions in Shigella dysenteriae serovars 4 and 16 and Escherichia coli O159 and O173 antisera. Molecular serotyping by PCR-RFLP of the rfb gene produced an S. dysenteriae serovar 2/E. coli O112ac pattern. They were positive by PCR for ipaH and ial enteroinvasive genes but negative for all other genes tested. Antiserum was prepared from one of the isolates and tested against Shigella and E. coli reference strains as well as the other isolates. The antiserum reacted with the five remaining isolates and showed cross-reactivity with S. dysenteriae serovars 1, 4, and 16; Shigella flexneri type 3; and E. coli O118, O159, O168, O172, and O173 antigens. Absorbing the sera with E. coli O159 and S. dysenteriae serovar 4 antigen removed all cross-reactions and only slightly reduced the homologous titer. Based on biochemical, molecular, and complete serological analysis, we propose that these six isolates represent a new provisional serovar of S. dysenteriae, type strain BEDP 02-5104.

The development of rapid and sensitive molecular techniques for the detection of Vibrio species would be useful for the surveillance of sporadic infections and management of major outbreaks. Comparative sequence analysis of the ftsZ gene in the predominant Vibrio species that cause human disease revealed distinct alleles for each examined species, including Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus. Light Upon eXtension (LUX) real-time PCR assays were developed to target these species-specific polymorphisms, and were successful in rapidly differentiating the major pathogenic Vibrio species. Luminex liquid microsphere array technology was used to develop a comprehensive assay capable of simultaneously detecting V. cholerae, V. parahaemolyticus and V. vulnificus. These assays permitted the identification of a presumptive V. parahaemolyticus isolate as Vibrio alginolyticus, which was verified using additional molecular characterization. INTRODUCTIONPathogenic species of the genus Vibrio pose a considerable public health threat as the causative agents of both sporadic and epidemic human infections. Cholera, caused by Vibrio cholerae, continues to spread globally in a seventh pandemic (O1 El Tor biotype), and the emergence of a non-O1 serogroup (O139 Bengal) has led to a new pandemic (Sack et al., 2004;Faruque & Mekalanos, 2003). Unlike the watery diarrhoeal disease caused by V. cholerae, infection with Vibrio parahaemolyticus usually results in a self-limiting gastroenteritis with inflammatory diarrhoea and, in rare cases, septicaemia (Janda et al., 1988). Opportunistic infections with Vibrio vulnificus can cause severe wound infections (Oliver, 2005) and fulminant septicaemia, with highly virulent strains causing extensive host-tissue damage and producing mortality rates of up to 60 % (Linkous & Oliver, 1999). The threat posed by pathogenic Vibrio species has been highlighted by recent natural disasters, in which a number of survivors were infected in the aftermath of Hurricanes Katrina and Rita on the gulf coast of the USA (Centers for Disease Control, 2005Control, , 2006, and the Indian Ocean tsunami (Lim, 2005). Fortunately, major outbreaks did not occur, but these disasters have served as an impetus to develop rapid and sensitive molecular techniques that can be easily deployed to identify pathogenic Vibrio species during a public health emergency.Traditionally, identification of Vibrio spp. has consisted of isolation on selective agar medium followed by biochemical and serological testing (Harwood et al., 2004). The availability of genomic sequence data allows for Vibrio spp. comparative genomic studies, revealing not only a wealth of information on their evolution and pathogenesis, but potential targets for molecular typing and detection. Molecular techniques for Vibrio identification and subtyping have been developed, including oligonucleotide probes (Wright et al., 1993) and DNA microarray technologies which target species-specific virulence determinants . PCR-based methods have been d...

Staphylococcus epidermidis is a major pathogen in early prosthetic valve endocarditis and cerebrospinal fluid shunt infections. Approximately 10 to 15% of hospital isolates are methicillin resistant. Ten clinically significant isolates of the latter were collected for antibiotic studies in vitro and in an experimental infection in animals. Time-kill studies of five strains showed gentamicin to be the single most effective antibiotic; however, dwarf colony variants emerged as survivors with two of these strains when challenged with gentamicin alone. The addition of a second antibiotic to gentamicin did not significantly improve the bactericidal rate but prevented the emergence of variant strains. A blood culture isolate of methicillin-resistant S. epidermidis combined with 5% hog gastric mucin was used to establish an experimental intraperitoneal infection in mice. Neither methicillin nor nafcillin treatment reduced mortality below that of untreated animals. Cephalothin treatment delayed early mortality but did not diminish overall mortality. Gentamicin was the most effective single antibiotic, and gentamicin in combination with vancomycin was the most effective regimen overall. The combination of rifampin plus vancomycin was as effective as gentamicin alone. The combinations of cephalothin or nafcillin with gentamicin and cephalothin with vancomycin demonstrated antagonism. The antagonism was not due to multiple injections or drug-drug inactivation.Staphylococcus epidermidis, in addition to being a common blood culture contaminant, may be an important cause of life-threatening infections. It is the predominant pathogen in meningitis associated with intraventricular shunts (30, 31) and early prosthetic valve endocarditis (14, 32) and accounts for 2 to 5% of reported cases of subacute bacterial endocarditis (9,18,21). Despite this clinical importance, appropriate antimicrobial therapy for S. epidermidis infections remains uncertain. Approximately 10 to 15% of S. epidermidis isolates are methicillin resistant (15,25). Susceptibilities of hospital isolates of this organism to other antibiotics are variable (1, 10), but routine antibiotic susceptibility studies usually suggest that strains of methicillin-resistant S. epidermnidis (MRSE) are susceptible to gentamicin, cephalothin, vancomycin, and rifampin (1, 10, 28