摘要:

A total of 965 cultures of streptococci received at a reference unit for identification were examined with API‐20 Strep kits and also by established methods. The API method, although it needed to be supplemented with additional tests, largely overcame the difficulty that pyogenic streptococci are usually identified by their serological reactions and that biochemical tests are used for the identification of the other streptococci. Representatives of at least 24 established or possible species were identifie

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02351.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

When applied to the psychrophilic and psychrotropic bacteria associated with diseases of fish, the disc‐diffusion method generally fails to provide correct estimates of minimal inhibitory concentrations (MIC). A microdilution method using a medium containing agar (15 g/l) and 10 selected drugs has been developed. Serial four‐fold dilutions of the drugs were performed in specially designed dilution plates, which were prepared and stored at −30° or −70°C. Although its reliability sometimes appeared to be influenced by the temperature at the time of testing, the temperature and duration of freezing and the nature of the drugs, the microtest provided results as accurate as other reference methods. In repeated experiments very rare major discrepancies were noted and minor variations of one dilution step were below 10%, except with tetracyclines and the sulphonamide‐trimethoprim mixture. The advantages of the method and the optimum conditions for use in fish disease diagnosis ar

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02352.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The microbial flora of 141 samples of raw ewes’milk was determined, before and after storage for 72 h at 4° and 7°C. Penicillin‐resistant bacteria representedca61% of 1760 psychrotrophic isolates from refrigerated milk samples.Pseudomonas fluorescensandPseudomonasfluorescent group‐related strains predominated (ca86%) in the Gram negative psychrotrophic microflora.Leuconostoc dextranicumwas the most frequent Gram positive psychrotrophic species i

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02353.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The experimental procedure described is designed to allow calculation of the radiation sterilization dose for medical devices to any desired standard of sterility assurance. The procedure makes use of the results of a series of sterility tests on device samples exposed to doses of radiation from 0.2 to 1.8 Mrad in 0.2 Mrad increments. From the sterility test data a 10‐2sterility level dose is determined. A formula is described that allows a value calledDSMrad to be calculated. This is an estimate of the effective radiation resistance of the heterogeneous microbial population remaining in the tail portion of the inactivation curve at the 10‐2dose and above.DSMrad is used as aD10value and is applied, in conjunction with the 10‐2sterility level dose, to an extrapolation factor to estimate a sufficient radiation sterilization dose. A computer simulation of the substerilization process has been carried out. This has allowed an extensive evaluation of the procedure, and the sterilization dose obtained from calculation to be compared with the actual dose required. Good agreement was obtained with most microbial populations examined, but examples of both overdosing and underdosing were found with microbial populations containing a proportion of organisms displaying pronounced shoulder inactivation kinetics. The method allows the radiation sterilization dose to be derived from the natural resistance of the microbial population to gamma steriliz

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02354.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Variants of the tetrazolium‐reduction, nalidixic acid‐inhibition and fluorescein diacetate‐hydrolysis techniques for enumeration of metabolically active bacteria were compared, using samples of planktonic, benthic, and epiphytic freshwater bacteria. Results obtained by these methods generally showed statistically significant differences. However, an INT reduction technique, without added substrate, and a slightly modified nalidixic acid procedure gave values which did not differ at the 5% level. The results indicated that from 10 to 40% of total bacteria in the samples examined were metabolically active. These values were up to two orders of magnitude higher than those obtained by conventional plate count techn

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02355.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A computer‐assisted probabilistic identification technique employing 18 carbon source utilization tests has been developed and applied to 787Pseudomonasstrains isolated from beef, pork and lamb stored under aerobic conditions. Seven hundred and twelve (89.7%) were identified using these tests alone and a further six (0.8%) with extra tests. Taxa detected werePs. fragicluster 2, 390 strains (49.6% of all isolates);Ps. fragicluster 1, 191 strains (24.9%); meat cluster 3, 87 strains (11.1%);Ps. fluorescensbiotype I, 31 strains (3.9%);Ps. fluorescensbiotype III, 7 strains (0.9%); andPs. putida, 1 strain (0.1%). The relative incidence of members of the various taxa was similar on beef, pork and lamb, and was unaffected by storage temperature in the range 0°–10°C. Each taxon was also detected at similar rates before and after spoilage. Meat origin (abattoir) affected the frequency of detection of meat cluster 3 andPs. fluorescensbiotype I strains but did not affect the incidence of detection of either cluster ofPs.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02356.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Myxococcus coralloidesD was found to produce a substance with a narrow range of antibacterial activity. This substance was produced during the exponential growth phase and was not inducible by ultraviolet light or mitomycin C treatment. The bacteriocin was precipitable by ammonium sulphate, and showed resistance to heat (100°C for 10 min), trypsin, lysozyme, β‐glucuronidase, DNase, RNase, acetone, ethyl ether, urea and mercaptoethanol; it was partially destroyed by pronase and inactivated at extreme pH values. Electron microscopy did not reveal any phage‐like particles associated with bacteriocin act

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02357.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Five strains representing four clusters of meat spoilage pseudomonads were grown on sterile beef at 5°C. After 7 days incubation sensory assessments were made and the chemical composition of the headspace gases determined by gas chromatography‐mass spectrometry. There was good correlation between odour descriptions and chemical data for three of the strains. The most numerous types of product were esters and sulphur‐containing compounds. Of 45 compounds identified only 1‐undecene was common to all the tested s

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02358.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Forty strains of ureolytic bacteria were isolated from the caecal content and soft faeces of seven rabbits by the anaerobic roll tube method and were characterized. The isolates were identified withClostridium coccoides, Cl. innocuum, Peptostreptococcus productus, P. micros, Peptococcus magnus, Fusobacterium russiiandFusobacteriumsp. Urease activity of representative strains of the various species was also determined. The study indicated that strongly‐ureolytic anaerobic bacteria are present in the caecum of the rabbi

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02359.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Pieces of fresh beef were inoculated with three strains ofCampylobacter jejuni. The meat was then allocated to three treatments: (a) vacuum packaged, (b) packaged in an atmosphere of 20% CO2+ 80% N2, and (c) packaged into sterile Petri dishes in anaerobic cultivation boxes, which were filled with a gas mixture of 5% O2+ 10% CO2+ 85% N2. The packaging material in the first two treatments was PA 80/PE 100–PE 100/PA 80/PE 100. The survival ofCampylobactercells was followed at 37°C, 20°C and 4°C for 48 h, 4 days and 25 days, respectively. At 37°C the counts of twoCampylobacterstrains increased in each package treatment for 48 h. At 20°C and at 4°C the counts of the same two strains decreased by 1 to 2 log units and 0.5 to 1 log unit, respectively, during storage. The survival of the two strains was about the same in all package treatments. The third strain was the most sensitive of the strains studied. At 37°C its numbers increased only in the optimal gas atmosphere; at 20°C the strain was not detectable after 24 to 48 h storage and at 4°C after 4 days storage. The aerobic plate counts were determined for all samples at the same time asCampylobactercounts. The high indigenous bacterial numbers of the meat samples did not appear to have a great effect on the survival or growth of camp

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1984.tb02360.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY