摘要:

Recovery ofListeriafrom raw and cooked meat products was compared using Fraser broth (FB) enrichment incubated at 30 and 35C for 24 and 48 h. the Micro‐IDListeriatest strip for biochemical characterization ofListeriawas also compared with conventional tests.Listeriaspp. were recovered from 33, 47, and 20 of the raw chicken, raw beef and cooked meat products, respectively. No false‐negative reactions were observed and more totalListeria‐positive samples were found using FB incubated for 48 h compared with 24 h. Samples incubated at 35C had fewer false negative tubes than those incubated at 30C. More false‐positive FB tubes were observed after 48 h than after 24 h incubation. Over half of the cooked samples did not hydrolyze the esculin and turn the tubes black, and therefore did not have to be streaked onto selective plates. However, with raw chicken or beef because of the large number of false‐positive FB tubes, almost all tubes had to be streaked onto selective plates and very little advantage was gained from using the FB. the Micro‐IDListeriatest kit gave a 100% correlation with conventional biochemical reactions for pure cultures ofListeriaisolated from the three categories of meat products in this study. When used in conjunction with hemolysis plates and CAMP reactions, this test identifies species ofListeriaisolates within 24 h of visible colon

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00073.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A rapid polymerase chain reaction (PCR) method was developed for detection of low numbers ofCampylobacter jejuni.In this method, PCR was run directly from lysedC. jejunicells and used a short denaturing and annealing time, a rapid transition, and an increased number of cycles to obtain good sensitivity. Only 3 h were required for PCR and 1 h for electrophoresis. Additional time for DNA isolation and DNA hybridization was not needed. This system was positive forC. jejunibut negative forC. coliandC. fetus.the method detected as few as two cells in original liquid ofC. jejuniin pure cultures. an internal probe hybridization test confirmed that the PCR products were fromC. jejuni.

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00074.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A simplified colony hybridization procedure was developed using sealed disposable plastic petri dishes in place of sealed plastic bags. Prior to hybridization, the dishes were sealed with successive layers of parafilm, plastic wrap and aluminum foil to prevent evaporation of the solution. This self‐contained procedure eliminates some of the technical problems such as spilling of radioactive materials, leakage of solution, sealing of plastic bags and the formation of air bubbles. Therefore, this method allows for safer and easier handling of radioactive materials during hybridization procedure

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00075.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Microbial analyses of pork loin surfaces and minced beef samples were done using aerobic plate count (APC) and spiral plate (Spiral) methods and manual counting (MC) and laser counting (LC) procedures.Connecting APC and Spiral techniques together was convenient, when analyzing pork surface swab samples. If APC plates were “too numerous to count,” Spiral plates could be used to get an estimation of the microbial numbers/cm2. Conversely when microbial numbers were too low for the Spiral technique, APC plates were easy to count.Good correlation was found among Spiral and APC plates counted manually and with the laser for both sample materials. For minced beef samples, Spiral‐MC and Spiral‐LC methods gave higher numbers than APC‐MC (63% of samples) and APC‐LC (49% of samples) (not significant at 0.05 level). When APC and Spiral results for minced beef samples were analyzed, LC gave higher microbial numbers compared to MC: 65% of the APC‐LC results were higher than APC‐MC results (statistically significant at 0.05 level), and 56% of Spiral‐LC results were higher than Spiral‐MC results (not significant at 0.05 level). Most minced beef results by all combinations of methods (APC‐MC / APC‐LC / Spiral‐MC / Spiral‐LC) were within a ± 0.5 logarithmic range, and a

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00076.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

This report describes the detection ofStaphylococcus aureusin buffer and in several kinds of food by flow cytometry. Fluorescein isothiocyanate conjugated anti‐protein A antibodies were used in a 4‐h procedure to label cells, 105‐106cells/mL are needed. the use of single parameter, green fluorescence, enabled specific differentiation ofS. aureusfrom other bacteria including 11Staphylococcusspecies. the flow cytometric method can detectS. aureusin food samples after 48‐h enrichment in trypticase soy broth with 10% NaCl. As low as 2S. aureuscells present in 10 mL enrichment broth could grow to a population density detectable by the flow cytometric method after enrichment. This method was faster and less laborious than the conventional BAM (Bacteriological Analytical Manual) or AOAC (Association of Official Analytical Chemists) methods, and could be automated for analysis ofS. aureus

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00077.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A staining procedure was developed for screeningClostridium botulinumtype A (tox+) cells fixed (smear) on glass slides. the method is based on reaction between cells and an immunoenzyme‐conjugate consisting of antibody against type A toxin linked to horseradish peroxidase (HRPO) enzyme. Fixed smears were stained for perioxidase activity (30 min), using one drop of 3,3′‐diaminobenzidine‐hydrogen peroxide solution (pH 7.6) as oxidizable substrate, followed by washing, drying and microscopic examination (1000 X). the cell‐walls of vegetativeC. botulinumtype A appeared reddish brown and periphery of spores (if present), stained dark brown. However,C. botulinumtype B (tox+) cross‐reacted (faint brown) with the same antibody‐HRPO‐conjugate. Specificity and sensitivity of this procedure compared well with the immunodiffusion method of Ferreiraet al.(1981, 1983). Factors affecting cell‐staining were: fixation time and type used, incubation time of antibody‐HRPO‐conjugate with cells, growth medium, culture age, and crowding of cells in smears. Ethanol fixation (5 min) of logarithmic and/or stationary phase cells and 30 min incubation with antibody‐HRPO‐conjugate were optimal and yielded the most appropriate procedure for detecting cells containi

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00078.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Clostridium perfringensis widely distributed in foods. This experiment was performed to assess occurrence ofC. perfringenscultures and toxigenic strains isolated from ground beef Samples (118) were collected from 20 locations in Northeast Kansas and the number ofC. perfringenswas enumerated in these samples by Fung's Double‐tube method with tryptose sulfite cycloserine agar medium. Out of 118 samples, 54 (46%) were found positive for C. perfringens. Pure isolates ofC. perfringenswere further grown in cooked meat medium for 24 h at 42C then heat shocked at 75C for 20 min and inoculated into modified Duncan and Strong medium for production ofC. perfringensenterotoxin. Presence of enterotoxin was tested by the reverse passive latex agglutination test (Oxoid), which can detect enterotoxin up to a minimum level of 2 ng/mL. the data indicate that 46% of the beef samples harboredC. perfringens, but only 32 (6%) of 525 isolates were found to produce enterotoxin. This study emphasized the importance of continued surveillance ofC. perfringensin meats and meat products and assessment of the toxigenesis of isolate

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00079.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Book reviewed in this Article:Analytical Microbiology Methods: Chromatography and Mass Spectrometry. 1990. Edited by Alvin Fox, Stephen L. Morgan

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00080.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY