Mean Aerobic Bacterial Count Research Articles

Detection of Salmonella and Enumeration of Hygienic Indicator Bacteria in Dried Wood Ear Mushrooms

An outbreak of Salmonella Stanley in the United States associated with dried wood ear mushrooms imported from China prompted us to conduct serotyping of Salmonella isolated from dried wood ear mushrooms in voluntary testing, and quantitative test for Salmonella along with enumeration of hygienic indicator bacteria in positive samples in order to evaluate the risk of Salmonella outbreak from dried wood ear mushrooms. The major serovars of Salmonella isolates obtained from 20 samples were as follows: O3,10 group-London (n=3) and Weltevreden (n=5) etc, totaling 9 strains; O4 serogroup-Saintpaul (n=2), Stanley (n=1), Typhimurium (including monophasic variant; n=3), totaling 6 strains. O7 serogroup (Potsdam) and O8 serogroup (Newport) were one strain each. Qualitative and quantitative tests for Salmonella were conducted on 10 samples with remaining amounts. As a result, one sample was 220 MPN/g, six samples were<0.6 MPN/g, and three samples were negative for Salmonella per 25 g. The mean aerobic bacterial counts and coliforms in these samples were 7.8 and 6.1 log10 CFU/g, respectively. Furthermore, qualitative test for Salmonella and enumeration of hygienic indicator bacteria were conducted on dried wood ear mushroom products (33 domestic and 30 imported products) retailed in Japan. No samples showed positive for Salmonella per 25 g, and the mean aerobic bacterial counts and coliforms were approximately 2 log10 CFU/g lower than those in the 10 samples where Salmonella was isolated during voluntary testing. While no Salmonella was detected in domestically retailed wood ear mushrooms products, the serovars associated with foodborne diseases were isolated from voluntary testing samples. It indicates that potential for consumption of Salmonella contaminated wood ear mushrooms, which is at risk of causing food poisoning.

Bacteriological Quality and Antimicrobial Resistant Patterns of Foodborne Pathogens Isolated from Commonly Vended Street Foods in Arba Minch Town, Southern Ethiopia.

Ready-to-eat foods sold by street vendors act as potential sources for the spread of various foodborne infectious diseases. Thus, local determination of the level of foodborne bacterial pathogens and their antimicrobial resistance pattern is essential. A community-based cross-sectional study was conducted from September 5th, 2022 to December 31th, 2022. The required data were collected by a structured questionnaire and observation checklist. Randomly selected street-vended foods were aseptically collected, and the bacteriological quality was assessed by using culture techniques. Different biochemical tests were used to identify and characterize bacterial isolates. The antimicrobial-resistant test for isolated foodborne bacterial pathogens was carried out by using the Kirby-Bauer disc diffusion method. The data were analyzed using SPSS version 22. A total of 34.2% (113/330) with a 95% CI of 29.1-39.4 of commonly consumed street-vended foods were identified as having unsatisfactory total mean aerobic bacterial counts (>105 CFU/g; 4.3 × 105 CFU/g). The mean total Enterobacteriaceae, coliform, and staphylococcal counts were found to be 1.4 × 105 CFU/g, 2.4 × 104 CFU/g, and 3.4 × 104 CFU/g, respectively. A total of 12.7% (42/330) of foodborne pathogens were recovered attributed to Staphylococcus aureus (31, 9.4%), Salmonella species (6, 1.8%), and E. coli O157:H7 (5, 1.5%). 6.5% and 16.1% of isolated S. aureus were found to be methicillin-resistant and multidrug-resistant (MDR), respectively. Additionally, 33.3% of Salmonella isolates and 40% of E. coli O157:H7 isolates were found to be MDR. Street-vended foods in this setting have a considerable number of unsatisfactory bacterial qualities, along with drug-resistant foodborne pathogens. Thus, more effective health education and training for vendors, regular inspections of vending sites, and regular surveillance of drug resistance patterns of foodborne pathogens are all essential.

Bacteriological profile, antimicrobial susceptibility patterns of the isolates among street vended foods and hygienic practice of vendors in Gondar town, Northwest Ethiopia: a cross sectional study

BackgroundThere are numerous advantages offered by street vended foods, but evidence exists that foods exposed for sale on the road side may be contaminated by pathogenic microorganisms. However, information on the bacteriological profile, bacterial load and antimicrobial susceptibility patterns of bacterial isolates from street food in Gondar town are lacking. The aim of this study was to assess bacterial profile, bacterial load, and antimicrobial susceptibility patterns of bacterial isolates among street vended foods and also the hygienic practice of vendors in Gondar town, Northwest Ethiopia.MethodsSocio-demographic characteristics and the hygienic practices of 24 vendors were collected using structured questionnaire. A total of 72 food samples from four different food items were analyzed and counted by standard aerobic plate count method. Ten grams of each food sample was transferred in to 90 ml of buffered peptone water and homogenized. The homogenates were serially dilute and a volume of 0.1 ml dilution was spread on solid media and incubated at 35-37 °C for 24 h. Antibiotic susceptibility testing was done for isolated species using Muller Hinton agar and data was entered and analyzed by using SPSS version 20.0.ResultsSeventy two food samples of street vended food were analysed for bacterial pathogens. 44/72 tested positive, a total of 63 isolates were identified as 19 samples contained two pathogens. The total mean aerobic bacterial count was 6.64 × 104 CFU/g which is varied from 1 × 104–1.86 × 105 CFU/g. S. aureus is the most frequent isolate 34 (53.96%) followed by E.coli 15(23.8%), Enterobacter species 10(15.87%) and Citrobacter species 4(6.3%). Gentamycin, chloramphenicol, tetracycline, ciprofloxacin, and trimethoprim-sulfamethoxazole were found to be the most effective antimicrobials against all isolates but the enterobactereaceae were resistant to ampicillin and Ceftaziidime and S.aureus were resistant to penicillin.ConclusionThe results of this study showed that, the majority of street-vended food items in Gondar were contaminated with one or more different pathogenic bacteria. The presence of these bacteria in foods could lead to potential health problems for consumers. Therefore, health education as well as training in food safety and hygienic handling is required for food handlers to minimize contamination and the likelihood of people falling ill.

Assessment of the effects of cassava mill effluent on the soil and its microbiota in Biase local government area of Cross river state, Nigeria

The effects of cassava mill effluent (CME) on the soil and soil micro-biota was investigated. Soil samples were collected from sites polluted with CME and also from an adjacent site not polluted with CME. Standard microbiological methods were used in the isolation, antibiotic susceptibility and enumerating the population of the microorganisms while the physico-chemical parameters of the soil were determined using standard chemical processes. The bacteria isolates were Bacillus sp., Pseudomonas sp., Enterobacter sp., Escherichia coli, Corynebacterium sp. and Proteus sp. and the fungal isolates were Aspergillus sp., Candida sp., Mucor sp., Penicillium sp., Saccharomyces sp. and Rhizopus sp. The mean aerobic bacterial count for the soil samples ranged from 7.1±0.11x105 cfu/g for the control soil to 8.0±0.19x105 cfu/g for the CME impacted soil. The mean heterotrophic fungal counts varied from 4.7±0.41x105 cfu/g for CME impacted soil to 4.2±0.57x105 cfu/g for the control soil. Susceptibility profile showed that Bacillus sp. from the CME impacted site had reduced susceptibility to levoflacin, amoxil, chloramphenicol, and Ciprofloxacin. Pseudomonas sp. from the same site had reduced susceptibility to streptomycin, ampicilin, tarivid, peflacin, augmentin and ciprofloxacin. Escherichia coli had reduced susceptibility to streptomycin, ampicilin, ciprorex and nalidixic acid. The heavy metals Cu, Zn, Ni, Co, and Fe content of the CME impacted soil increased greatly. Excessive application of CME had negative effects on the soil, hence the high concentration of heavy metals in CME dumpsites and high microbial presence. The study also showed that CME can induce the resistance potential of some soil microbes to antibiotics and seriously affect the physicochemical parameters of soil.

Bacterial and fungal burden of local packing papers used for roasted meat in Kano State Nigeria

Background: The appetite for fast food in developing countries continues to rise although plans to regulate how these foods are safely delivered to the consumers are not common if they exist. Objective: To determine the Bacterial and fungal burdens of local packing papers used for roasted meat in Kano State Nigeria. Materials and Methods: Standard microbiological methods were used to determine the bacterial and fungal loads of 108 locally improvised packaging papers for fast food roasted meats in strategic locations of the Kano metropolis. The packaging materials were obtained from consenting roasted meat vendors in the Kano metropolis. Appropriate aseptic precautions were adopted to ensure a good, reliable, and reproducible result. Result: The mean aerobic bacterial count observed ranged between 9.9 x 104 and 2.47 x 105 –3.09 x 102 cfu/ml and 1, 24 to 3.09 x 102 cfu/ml for fungi respectively. High counts of both bacteria and fungi were found in samples of meat wrapping papers. B. cereus and E. coli were isolated from 55% and 100% of samples of meat wrapping papers respectively. The roasted meat wrapping papers included old newspapers (80%), used exercise books (8%), and disposed of office printed stationeries (12%). The most probable bacterial number MPN showed that the papers for meat packaging were more exposed to contamination (75MPN/ml) while the paper plate had (7MPN/ml). Conclusion: The papers used for roasted meat fast food were found to be unsafe and unfit for packaging purposes as they can easily be a source of disease epidemic due to the confirmed loads of bacterial and fungal pathogens. The factory sterilized paper plates are also not free from microbial contamination but might be due to exposure to unsanitary storage and marketing conditions during delivery to end-users.

Production of an 18% protein liquid micellar casein concentrate with a long refrigerated shelf life

Our objective was to develop a process to produce a high-concentration liquid micellar casein concentrate (18% protein, MCC18) with a long refrigerated shelf life. The MCC18 is a novel milk protein ingredient produced by fractionating skim milk using microfiltration (MF). To achieve a long refrigerated shelf life, the processing of MCC18 was designed to maximize the removal of low-molecular weight compounds [e.g., lactose and nonprotein nitrogen (NPN)] that can be easily metabolized by microbes, while minimizing the microbial count in the final product. The production of MCC18 was done over a period of 5 d. The experiment was replicated 3 times in different weeks with a different batch of raw milk. Raw whole milk was pasteurized and separated to produce skim milk. Skim milk was ultrafiltered (UF) to remove more than half of the lactose and NPN. The UF milk retentate was diluted with water and then MF in 3 stages to remove approximately 95% of the serum protein and further remove lactose and NPN. The retentate from the last stage of MF was UF to concentrate the protein to 18% and batch pasteurized. The MCC18 was collected immediately after processing in sterile plastic vials and stored at 4°C. The average MCC18 contained 21.78% total solids, 18.27% true protein, 0.31% NPN, and 0.13% lactose. The MCC18 at the day of processing contained a mean aerobic bacterial count of 2.1 log cfu/mL and mean aerobic spore count of 2.3logcfu/mL. The MCC18 formed a solid gel at temperatures <22°C, but the MCC18 reverted back to a liquid when warmed from 4°C temperature to >22°C. This provides a unique opportunity in ingredient handling and packaging and eliminates the challenges encountered in reconstitution of dried milk protein ingredients. The MCC18 produced in this study maintained a bacteria count <20,000 cfu/mL for 16wk when stored at a refrigeration temperature of 4°C. Further study is needed to determine if changes occur in the organoleptic and functional properties of MCC18. We envision that the conversion of skim milk to MCC and its coproducts (serum protein concentrate and lactose concentrate) could be used as an alternative to the production of nonfat dry milk to balance milk production seasonality, specifically the components of skim milk portion.

IMPACT OF ABATTOIR EFFLUENT ON THE BACTERIOLOGICAL AND PHYSIOCHEMICAL PROPERTIES OF IKPOBA RIVER, EDO STATE NIGERIA

The bacteriological and physicochemical properties of Ikpoba River water quality was studied. Sampling was carried out from 3 sampling points designated as station 1 (100 meters before the point were abattoir effluent is discharged into the River), station 2 (the point were abatoir effluent enters the river) and station 3 (100 meters away from station 2). The mean aerobic bacterial counts obtained during the months of September and October ranged from 7.58 x 103 to 11.65 x 103 cfu/ml across the sampling points while the aerobic bacterial counts during the months of November and December ranged from 6.80 x 103 to 1.03 x 104 cfu/ml. Total coliform counts ranged from 8.0 X 104 to 1.15 X 105cfu/ml while the mean E. coli counts ranged from 3.10× 104 to 1.10 × 105cfu/ml. The cultural, morphological and biochemical characterization of the isolates showed the presence of the bacterial genera, Staphylococcus, Klebsiella, Citrobacter, Escherichi, Pseudomonas, Enterococcus and Bacillus. The pH, temperature, turbidity, dissolved oxygen, phosphate, biochemical oxygen demand, chemical oxygen demand, electrolytic conductivity, nitrates and sulphate values fluctuated between the sampling points. The presence of different bacterial genera in this river could largely be attributed to the inflow of the effluents into the river and hence, call for serious concern

Salmonella Prevalence in Seafood Imported into Japan

A total of 353 samples of 29 types of seafood were tested for Salmonella prevalence and total microbial population. Salmonella enterica serotype Weltevreden was isolated from 2 of 47 black tiger prawn samples. The contamination levels of Salmonella were in a range of <30 to 40 most probable number per 100 g. In addition, one sample of black tiger prawns and two samples of white shrimp were positive for SalmonellainvA gene on PCR assay. Although the mean aerobic bacterial count was greater than 4 log CFU/g in most of the sample types, those in the two Salmonella-isolated samples of black tiger prawn were 7.48 and 5.18 log CFU/g, respectively. These results indicate the possibility that shrimp and prawns contribute to foodborne infections. The improvement of seafood quality is an important issue, and the information on contamination by pathogens should be provided as feedback to the originating country, with the aim of increasing safety.

Salmonella Prevalence and Total Microbial and Spore Populations in Spices Imported to Japan

A total of 259 samples of 40 types of spices were tested for Salmonella prevalence and total microbial and spore populations. Salmonella enterica serotypes Weltevreden and Senftenberg were isolated from a black- and red-pepper sample, respectively. Because Salmonella was not detected by the most-probable-number method, it indicated that at least one cell of the microorganism was present in 25 g of sample. The mean aerobic bacterial count was greater than 5.39 log CFU/g in turmeric, garam masala, curry powder, and paprika. The mean bacterial spore counts were greater than 4.33 log CFU/g in turmeric and curry powder. The mean aerobic bacterial count in the two Salmonella-isolated samples was 6.93 log CFU/g. These results indicate that spices can be a source of contamination in the products where they are used as ingredients, and methods to reduce the microbial load in spices should be used.

Microbiological Survey of Tofu Sold in a Rural Illinois County

The purpose of this study was to determine the microbial status of tofu sold in a rural Illinois county and assess the factors contributing to the safety of tofu. Six brands of tofu from eight different stores (60 total samples) were purchased and analyzed for temperature, pH, total aerobic bacteria, and the presence of coliforms. Relationships between age, temperature, pH of tofu, and total aerobic bacteria were tested. An analysis of variance was also performed to test for differences in total bacterial counts among the brands. Mean aerobic bacterial counts ranged from 0 to 7.76 × 107 CFU/g. Fifty-five percent of the tofu tested fell within the excellent range for freshness as delineated by the standards developed by the Soyfoods Association of North America, 6.7% fell within the acceptable range, 6.7% within the marginal range, and 28% within the unacceptable range. Sixteen percent of the samples contained coliform bacteria. No significant correlation was found between variables, except pH with total aerobic bacterial counts (r = −0.51) and pH with eosin-methylene blue agar counts (r = −0.67). Most of the tofu was displayed at unsafe temperatures (>5°C) for potentially hazardous foods. This study confirmed the concerns regarding safety of tofu sold in the grocery stores. Based on these results, special training on tofu storage and handling is recommended for grocery stores selling this food product.