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New enrichment method for isolation of pathogenic Yersinia enterocolitica serogroup O:3 from pork.

A new enrichment medium for the recovery of pathogenic Yersinia enterocolitica serogroup O:3 from naturally infected meat products based on three selective agents, Irgasan, ticarcillin, and potassium chlorate (ITC), was compared with several other one- or two-step enrichments. Y. enterocolitica serogroup O:3 was recovered from 96.5% of 29 pork tongues, 24% of 50 ground pork samples, 16% of 25 masseter muscle samples, and 61% of tonsils. ITC was by far the most sensitive method for the recovery of Y. enterocolitica O:3, especially from ground meat and masseter muscles, while cold and two-step enrichments yielded better results for nonpathogenic strains. Plating of ITC enrichments onto SS-deoxycholate-calcium agar gave overall better results than plating onto cefsulodin-Irgasan-novobiocin agar for serogroup O:3.

Animals↗

Low occurrence of pathogenic Yersinia enterocolitica in clinical, food, and environmental samples: a methodological problem.

While Yersinia enterocolitica is an important pathogen, which can cause yersiniosis in humans and animals, its epidemiology remains obscure. The pig is the major reservoir of pathogenic Y. enterocolitica of bioserotype 4/O:3, the most common type found in humans. Y. enterocolitica is thought to be a significant food-borne pathogen, although pathogenic isolates have seldom been recovered from foods. The low isolation rate of this pathogenic bacterium in natural samples, including clinical, food, and environmental samples, may be due to the limited sensitivity of culture methods. During the last decade, numerous DNA-based methods, such as PCR and colony hybridization assays, have been designed to detect pathogenic Y. enterocolitica in natural samples more rapidly and with better sensitivity than can be achieved by culture methods. In addition, the occurrence of pathogenic Y. enterocolitica in natural samples is clearly higher with PCR than with culture methods. The methods available for detection of pathogenic Y. enterocolitica in natural samples are reviewed in this article.

Bacteriological Techniques↗

Rickettsia felis: a new species of pathogenic rickettsia isolated from cat fleas.

A flea-borne rickettsia, previously referred to as ELB, has been implicated as a cause of human illness. Using sequence data obtained from a fragment of the citrate synthase gene, we compared ELB, Rickettsia australis, R. rickettsii, and R. akari with the louse-borne R. prowazekii. We tallied 24 base pair differences between ELB and R. prowazekii and 25 between R. rickettsii and R. prowazekii; there were 30 base pair differences between R. australis and R. prowazekii and 29 between R. akari and R. prowazekii. We observed 32 differences between Rickettsia typhi and ELB. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analyses of ELB, with typing sera against R. typhi indicate that ELB surface antigens are more closely related to the flea-borne R. typhi than to the mite-borne R. akari. On the basis of the results of citrate synthase gene sequence comparisons, as well as previous comparisons with 16S rRNA and 17-kDa-protein gene segments, we found that ELB is sufficiently genetically distinct from other rickettsiae to be designated a new species, Rickettsia felis.

Animals↗

Pathogenic microbes isolated from rabbit urine.

Asymptomatic urinary tract infections were recovered from the urine of 40 of 100 rabbits, and identical bacteria were isolated when the rabbits were retested. Urine samples which yielded significant growths of bacteria also had pus cells. Some specimens yielded more than 2 different isolates, and staphylococci were the most frequently isolated bacteria. Oxalate and uric acid crystals were seen in 6% of the samples, particularly those with significant growths of Pseudomonas aeruginosa. No ova, parasites or fungal elements were seen in 'wet-mount' preparations and no fungi were seen when urine samples were cultured. Female rabbits showed a higher number of bacterial isolates than males. Animals with significant isolates were treated with suitable antibiotics and repeat samples yielded no growth.

Animals↗

In vitro fungistatic and fungicidal activities of silver sulfadiazine and natamycin on pathogenic fungi isolated from horses with keratomycosis.

OBJECTIVE: To evaluate the in vitro antifungal properties of silver sulfadiazine (SSD) and natamycin against filamentous fungi isolated from eyes of horses with keratomycosis. SAMPLE POPULATION: Filamentous fungal isolates obtained from eyes of keratomycosis-affected horses. PROCEDURES: Fungal culture of ocular samples yielded 6 Fusarium spp; 7 Aspergillus spp; and 1 isolate each of Curvularia, Scopulariopsis, Penicillium, and Chrysosporium. For each fungal isolate, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of SSD and natamycin were determined. RESULTS: For all 17 fungal isolates, SSD MIC distribution ranged from < or = 1 to > 64 microg/mL; MIC50 and MIC90 (MICs at which 50% and 90% of organisms were inhibited) were 4 and 32 microg/mL, respectively. The SSD MFC distribution for all isolates was < or = 1 to > 64 microg/mL; MFC50 and MFC90 (MFCs at which 50% and 90% of organisms were killed) were 8 and > 64 microg/mL, respectively. For all fungal isolates, natamycin MIC distribution ranged from 256 to > 1,000 microg/mL; MIC50 and MIC90 were 512 and > 1,000 microg/mL, respectively. The natamycin MFC distribution for all isolates ranged from 512 to > 1,000 microg/mL; MFC(50) and MFC(90) were each > 1,000 microg/mL. CONCLUSIONS AND CLINICAL RELEVANCE: These in vitro data suggest that SSD is fungicidal against the fungal isolates that were obtained from eyes of horses with keratomycosis and that natamycin is fungicidal against some of the isolates at the drug concentrations evaluated. Silver sulfadiazine may be a therapeutic option for equine keratomycosis.

Animals↗

Acanthamoeba sohi, n. sp., a pathogenic Korean isolate YM-4 from a freshwater fish.

A new species of Acanthamoeba was isolated from a freshwater fish in Korea and tentatively named Acanthamoeba sp. YM-4 (Korean isolate YM-4). The trophozoites were 11.0-23.0 micrometer in length and had hyaline filamentous projections. Cysts were similar to those of A. culbertsoni and A. royreba, which were previously designated as Acanthamoeba group III. Acanthamoeba YM-4 can survive at 40 degrees C, and its generation time was 19.6 hr, which was longer than that of A. culbertsoni. In terms of the in vitro cytotoxicity of lysates, Acanthamoeba YM-4 was weaker than A. culbertsoni, but stronger than A. polyphaga. On the basis of the mortality of experimentally infected mice, Acanthamoeba YM-4 was found to be highly virulent. The isoenzymes profile of Acanthamoeba YM-4 was similar to that of A. royreba. An anti-Acanthamoeba YM-4 monoclonal antibody, McAY7, was found to react only with Acanthamoeba YM-4, and not with A. culbertsoni. Random amplified polymorphic DNA marker analysis and RFLP analysis of mitochondrial DNA and of 18S small subunit ribosomal RNA, placed Acanthamoeba YM-4 in a separate cluster on the basis of phylogenetic distances. Thus the Acanthamoeba Korean isolate YM-4 was identified as a new species, and assigned as Acanthamoeba sohi.

Acanthamoeba↗

[Detection and serological screening of conditionally-pathogenic enterobacteria isolated from food products and the environment].

The spread of some coliform bacteria in foods, the faeces of children and adults and in human environment was studied, and the evaluation of their toxigenic potential and serological properties was given. More then 160 strains of enterobacteria including 70 strains of Escherichia spp were described. The frequency of detection enterotoxigenic E. coli in foods--18%--was approximately similar an amount of ETEC strains which was isolated in humans (22%). 3 strains of E. coli) 157 were found in foods and in clinical samples (1.9%). The observed results have confirmed the proposal about the increasing of ETEC E. coli food-borne transmitting and dissemination its in the environment.

Adult↗

[beta-lactamase-producing activity and antimicrobial susceptibility of major pathogenic bacteria isolated from clinical samples. Japan beta-lactamase Research Group].

beta-Lactamase production and susceptibility to an assortment of antimicrobial agents were examined in 9,483 strains of organisms isolated from clinical materials obtained from inpatients and outpatients at 104 institutions throughout Japan from December 1999 to February 2000. The organisms were Staphylococcus aureus, 1,369 strains, including 847 methicillin-resistant (MRSA) strains; Enterococcus faecalis, 735 strains; Enterococcus faecium, 302 strains; Moraxella (Branhamella) catarrhalis, 730 strains; Haemophilus influenzae, 1,142 strains; Escherichia coli, 1,276 strains; Klebsiella pneumoniae, 1,058 strains; Enterobacter cloacae, 772 strains; Serratia marcescens, 847 strains; and Pseudomonas aeruginosa, 1,252 strains. The 23 antimicrobial agents used were ampicillin, sulbactam/ampicillin, clavulanic acid/amoxicillin, oxacillin, piperacillin, cefazolin, cefotiam, cefmetazole, cefoperazone, sulbactam/cefoperazone, cefotaxime, ceftazidime, cefepime, cefpodoxime, imipenem, gentamicin, arbekacin, clarithromycin, minocycline, chloramphenicol, vancomycin, teicoplanin, and levofloxacin. Antimicrobial agents appropriate for each organism were used. Among S. aureus strains, 61.9% were MRSA, and 62.3% were positive for beta-lactamase. Among the MRSA strains, none was resistant to vancomycin or teicoplanin, and only 3% were resistant to arbekacin. There was no vancomycin resistance in the Enterococcus strains. Only 0.1% of E. faecalis strains were ampicillin-resistant. Among the M. catarrhalis strains, 97.5% produced beta-lactamase, while among the H. influenzae strains, 8.5% produced beta-lactamase and 14.5% were beta-lactamase-negative and ampicillin-resistant (BLNAR). Among the Enterobacteriaceae and P. aeruginosa strains, there were 20 (E. coli; 7/1,276, K. pneumoniae; 13/1,058) that produced extended-spectrum beta-lactamases (ESBLs), and 11 that produced class B beta-lactamases. Multiple drug resistance was advanced in every species, and organisms resistant to 7 or more common antimicrobial agents were isolated. The best combination of antimicrobial agent and beta-lactamase inhibitor was sulbactam/cefoperazone. Sulbactam/cefoperazone, cefepime, and imipenem still have excellent antimicrobial activity. Rates of resistance to each antimicrobial agent differed more among institutions than among geographical regions.

Bacteria↗

[Antibiotic susceptibility and beta-lactamase activity of pathogenic microbes isolated in Miyagi Prefecture between December in 1999 and February in 2000].

We determined beta-lactamase activity and antimicrobial susceptibility of 556 strains consisting of 10 species isolated in four medical institutions and one microbiological laboratory of Miyagi Prefecture in Japan between December in 1999 and February in 2000. beta-Lactamase determined by nitrocefin method was positive in 68% of S. aureus, in 15% of H. influenzae and in 100% of M. catarrhalis. Penicillinase/cephalosporinase determined by acidometry was positive in 9%/10% of E. coli, in 17%/2% of K. pneumoniae, in 16%/58% of E. cloacae, in 43%/78% of S. marcescens, and in 4%/32% of P. aeruginosa, respectively. Of a total of 298 strains of Enterobacteriaceae and P. aeruginosa, 25 strains (14 strains of E. coli, 10 strains of K. pneumoniae and one strain of S. marcescens) produced class A beta-lactamase, two strains of E. cloacae produced class B beta-lactamase, and 12 strains (one strain of E. coli, four strains of E. cloacae, six strains of S. marcescens and one strain of P. aeruginosa) produced class C beta-lactamase. According to NCCLS standard, three strains (one strain of E. coli and two strains of K. pneumoniae) of ESBL-positive microbes were detected. beta-Lactamase-negative ampicillin-resistant (BLNAR) strains of H. influenzae were found in 10/40 (25.0%) of the strains tested.

Enterobacteriaceae↗