[Serovars and Drug-Resistance of Salmonella Strains Isolated from Domestic Chicken Meat in Tokyo (1992-2012)].

A total of 477 Salmonella strains isolated from retail domestic chicken meat during 1992-2012 in Tokyo, were examined regarding their serovars and drug-resistance. These strains were detected in 469 (29.8%) of 1,576 samples. The detection rate in every two years was 10.1% to 46.3% of the range. Serological typing results showed that 477 strains were classified into 22 serovars excepting 2 untypable strains. Among them, S. Infantis (312 strains) was the most prevalent, followed by II O4: b: [e, n, x] (S. II Sofia) (71 strains), S. Hadar (20 strains), S. Typhimurium (20 strains), S. Manhattan (12 strains), S. Schwarzengrund (9 strains), S. Agona (7 strains), and other 15 serovars (24 strains). Results of the antibacterial drug susceptibility test for 477 strains revealed that 89.9% was resistant to some of the 12 drugs tested, and multidrug-resistant strains accounted for 90.2% among them. The frequencies of resistance to each drug were 81.8%; 77.8%, 45.5%, 33.3%, 11.3%, 9.6%, 2.9%, 0.6%, 0.6% and 0.2%, in order with high frequency, for SM, TC, KM, ST, NA, ABPC, CP, FOM, CTX and CAZ, respectively. None of the strains was resistant to NFLX or IPM. Three CTX-resistant strains were CTX-M type extended-spectrum ß-lactamase (ESBL) producers, and the group of CTX-M type ESBL genes were CTX-M-2 group (2 strains) and CTX-M-9 group (1 strain). CAZ-resistant 1 strain was an ESBL producer, but the ESBL gene was not determined.

Detection of the staphylococcal enterotoxin D-like gene from staphylococcal food poisoning isolates over the last two decades in Tokyo.

The plasmid is a very well-known mobile genetic element that participates in the acquisition of virulence genes, such as staphylococcal enterotoxins (SEs), via horizontal transfer. SEs are emetic toxins and causative agents in staphylococcal food poisoning (SFP). We herein identified the types of plasmids harbored by seven SFP isolates and examined their production of plasmid-related SE/SEl to determine whether the new types of plasmid-related SE or SE-like (SEl) toxins (i.e. SElJ and SER) were involved in SFP. These isolates harbored pIB485-like plasmids, and all, except for one isolate, produced SElJ and SER. The amount of SER produced by each isolate accounted for the highest or second highest percentage of the total amount of SE/SEl produced. These new types of plasmid-related SE/SEls as well as classical SE may play a role in SFP. The seven isolates were classified into two SED-production types; a high SED-production type (>500 ng/ml) and no SED-production type. A nucleotide sequencing analysis revealed that three plasmids harbored by the SED-non-producing isolates had a single-base deletion in the sed gene with a resulting stop codon (from 233 amino acids of the intact SED to 154 amino acids of the mutant SED (mSED)). A real-time reverse transcription-PCR analysis showed that the mRNA of the msed gene was transcribed in the isolates. If the msed gene was translated as a protein, mSED may act as an emetic toxin instead of intact SED.

Molecular characterization of serologically atypical provisional serovars of Shigella isolates from Kolkata, India.

During 2000-2004, 13 Shigella strains that were untypable by commercially available antisera were isolated from children <5 years of age with acute diarrhoea in Kolkata. These strains were subsequently identified as Shigella dysenteriae provisional serovar 204/96 (n = 3), Shigella dysenteriae provisional serovar E23507 (n = 1), Shigella dysenteriae provisional serovar I9809-73 (n = 1), Shigella dysenteriae provisional serovar 93-119 (n = 1), Shigella flexneri provisional serovar 88-893 (n = 6) and Shigella boydii provisional serovar E16553 (n = 1). In this study, characterization of those provisional serovars of Shigella was performed with respect to their antimicrobial resistance, plasmids, virulence genes and PFGE profiles. The drug resistant strains (n = 10) of Shigella identified in this study possessed various antibiotic resistance genetic markers like catA (for chloramphenicol resistance); tetA and tetB (for tetracycline resistance); dfrA1 and sul2 (for co-trimoxazole resistance); aadA1, strA and strB (for streptomycin resistance) and blaOXA-1 (for ampicillin resistance). Class 1 and/or class 2 integrons were present in eight resistant strains. Three study strains were pan-susceptible. A single mutation in the gyrA gene (serine to leucine at codon 83) was present in four quinolone resistant strains. The virulence gene ipaH (invasion plasmid antigen H) was uniformly present in all strains in this study, but the stx (Shiga toxin) and set1 (Shigella enterotoxin 1) genes were absent. Other virulence genes like ial (invasion associated locus) and sen (Shigella enterotoxin 2) were occasionally present. A large plasmid of 212 kb and of incompatibility type IncFIIA was present in the majority of the strains (n = 10) and diversity was noticed in the smaller plasmid profiles of these strains even within the same provisional serovars. PFGE profile analysis showed the presence of multiple unrelated clones among the isolates of provisional Shigella serovars. To the best of our knowledge, this is the first report on the phenotypic and molecular characterization of provisional serovars of Shigella isolates from Kolkata, India.

Association between aggregative adherence fimbriae types including putative new variants and virulence-related genes and clump formation among aggR-positive Escherichia coli strains isolated in Thailand and Japan.

Enteroaggregative Escherichia coli (EAggEC) are an important cause of diarrhea. Four types of AAF have been identified; however, their prevalence and association with virulence properties remain unclear. E. coli strains carrying the aggR gene as EAggEC that were isolated in Japan and Thailand (n = 90) were examined for AAF subunit genes, two toxin genes (pet/astA), and clump formation. The most prevalent AAF gene was hdaA (28%), followed by aafA (20%), aggA (12%), and agg3A (4%), as well as a putative new AAF sequence (25.6%). Retention status of the toxin genes and intensities of clump formation appeared to vary according to the AAF type.

Emergence and genetic diversity of El Tor Vibrio cholerae O1 that possess classical biotype ctxB among travel-associated cases of cholera in Japan.

Vibrio cholerae O1 are classified into two biotypes, classical and El Tor, each encoding a biotype-specific cholera toxin. However, El Tor strains have recently emerged with a classical cholera-toxin genotype (El Tor variant). We characterized El Tor strains of V. cholerae O1 from travel-associated cases of cholera in Japan isolated from 1991 to 2006 by cholera toxin B subunit gene (ctxB) typing and by molecular epidemiological methods. ctxB in the biotype El Tor shifted from the El Tor-specific type to the classical-specific type around 1993, and this type fully dominated the later half of the 1990s. Based on the results of PFGE and multilocus variable-number tandem repeat analysis, strains of the classical biotype remained diverse from those of El Tor biotype. The El Tor biotype strains formed multiple minor clusters and intermingled with each other irrespective of their origins and toxin types. El Tor variant strains are widespread in Asian countries and show significant genetic diversity, indicating that their spread is a result of multiclonal expansion rather than spread from a single clone.

[Cefotaxime-resistant shiga toxin-producing Escherichia coli O26 : H11 isolated from a patient with diarrhea].

A shiga toxin-producing Escherichia coli (STEC) O26 strain resistant to cefotaxime (CTX) and cefpodoxime (but not ceftazidime) was isolated from the faecal sample of a 17-year-old outpatient with diarrhea. The double disk synergy test, twin test, polymerase chain reaction and sequence analysis confirmed that the strain produced CTX-M-3 type extended-spectrum beta-lactamase (ESBL). Conjugation experiment results suggested that the CTX resistance in this strain was determined by an approximately 85kbp plasmid that was readily transferable to a susceptible recipient E. coli strain. This is the first report from Japan of CTX-M-3type ESBL-producing STEC O26.

Flavonol glycosides in leaves of two Diospyros species.

Fourteen flavonol glycosides including two new compounds were isolated from the leaves of two Diospyros plants (D. cathayensis and D. rhombifolia). The structures of isolated compounds were determined by spectroscopic analysis. The scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical of the isolated compounds was also investigated.

[Increasing drug resistance in Vibrio cholerae O1 and non-O1 strains isolated from diarrheal cases in Japan].

Drug resistance trends were investigated for 271 Vibrio cholerae O1 (V.c O1) and 401 V. cholerae non-O1 (V.c non-O1) strains isolated from mainly imported diarrheal cases during 1981-2001 in Japan. The results of drug resistance test using 8 drugs (CP, TC, SM, KM, ABPC, ST, NA, and NFLX) showed that 34.7% of the V. c O1 strains and 15.7% of V.c non-O1 strains were multi-drug or mono-drug resistant. The incidence of drug resistant strains has increased since 1991, and it has been remarkable in V.c O1 strains that increased from 1.2% in 1981-1985 to 70.8% in 1996-2001. The drug resistance patterns of the resistant strains classified into 6 types in V.c O1 and 21 types in V.c non-O1. The prevalent patterns recognized were SM (75.5%), CP.TC.SM.ST (10.6%) and CP.SM.ST (8.5%) in V.c O1, and SM (25.4%) and ABPC (25.4%) in V.c non-O1. Ten V.c O1 strains (3.7%) and 10 V.c non-O1 strains (2.5%) were multi-drug resistant including TC. Among those, 13 strains were isolated from travelers who returned to Japan from Thailand. One V.c O1 strain (0.4%) and 6 V.c non-O1 strains (1.5%) were NA high-resistant and fluoroquinolones low-sensitive. Among those, 4 strains were isolated from travelers who returned to Japan from India.

Shigella dysenteriae serotype 1, Kolkata, India.

Since July 2002, bacteriologically confirmed shigellosis cases have increased, and multidrug-resistant Shigella dysenteriae serotype 1 strains have reemerged in patients hospitalized with diarrhea in Kolkata, India. The isolated strains of S. dysenteriae 1 showed resistance to chloramphenicol (80%), ampicillin (100%), tetracycline (100%), co-trimoxazole (100%), nalidixic acid (100%), norfloxacin (100%), and ciprofloxacin (100%). Emergence of fluoroquinolone resistance in S. dysenteriae 1 strains complicated treatment of shigellosis patients. Six strains belonging to provisional serovars of S. dysenteriae were also identified for the first time in patients hospitalized with diarrhea in Kolkata, India.

[Shigella boydii strains possessing a new serovar (SM00-27) isolated from diarrhea of overseas travelers in Japan].

Five Shigella strains isolated from stool cultures of five sporadic imported diarrheal cases in Japan during 1999-2001, did not react to any antisera of the established Shigella serovars. These strains had the typical biochemical characteristics of Shigella boydii, and were biochemically identical. All strains were positive in a PCR assay and a cultured-cell invasion test for invasiveness; these indicate that they can cause shigellosis in humans. The results of antigenic analysis revealed that they did not belong to any of the recognized or provisional serovars, and were serologically indistinguishable. Strain SM00-27 is designated as the test strain for this new S. boydii serovar.