Total Aerobic Bacterial Counts Research Articles

Microbial contamination of cosmetics and personal care items in Egypt--shaving creams and shampoos.

We examined a total of 192 samples, including eight different brands of shaving cream and eight brands of shampoo, for their total aerobic bacterial, coliforms and fungal counts. Shaving creams were more heavily contaminated with bacteria than shampoos. Viable bacterial were not recovered from 57% and 10% of shampoos and shaving creams, respectively. Only 3% of shaving creams were heavily contaminated with more than 10(4) c.f.u./g, while none of the shampoos contained such a high number of bacteria. With regard to the medium range contamination levels, 52% of shaving creams showed bacterial counts ranging from 10(2) to 10(3) c.f.u./g or ml, compared to 15% of shampoos which were contaminated to the same level. Fourteen per cent of shaving creams were contaminated with greater than 10(3)-10(4) c.f.u./g or ml, compared to 1% of the shampoos. No coliforms were recovered from either the shaving creams or the shampoos; however, Staphylococcus spp. were detected in six samples of both shampoos and shaving creams. Some of these Staphylococci, were aureus type. One isolate of Pseudomonas aeruginosa was also detected in a sample of shampoo. The incidence of fungal contamination was much less than the bacterial contamination. No viable fungi were recovered from 88% and 76% of the shaving creams and shampoos, respectively. The majority of the remaining samples, for both products, were contaminated with less than 100 fungal cell/g or ml. The pH of all the tested samples was alkaline (pH 7.2-9), which is well known to inhibit fungal contamination.

Quality changes of European catfish (Silurus glanis) from warm‐water aquaculture during storage on ice

SummaryGutted European catfish (Silurus glanis) from warm‐water aquaculture was stored in ice for 30 days. The limit of saleability was reached after approximately 20 days, and cooked fillets became inedible after about 27 days. Quality changes were investigated using established analytical methods; pH, total volatile bases (TVB), thiobarbituric acid number and texture measurements by Instron were not usefully predictive of shelf‐life or possible storage time. The Fish Tester and Torrymeter values decreased from 848 to 376 and 111 to 61, respectively. On day 27 the total aerobic bacterial counts had reached some 108/cm2 skin surface but only 105/g muscle. Hypoxanthine concentrations increased steadily to 17.2 mg/100 g, and ammonia levels increased from 11.5 to 18.7 mg/100 g muscle. There were no differences in the patterns obtained by isoelectric focusing of sarcoplasmic proteins from fresh and spoiled European catfish.

Lactic Acid Concentration and Microbial Spoilage in Anaerobically and Aerobically Stored Ground Beef

Lactic acid concentration of coarsely ground beef, packaged in low oxygen permeability casings, is inversely related to sensory acceptability of the meat following regrinding and aerobic storage for six additional days. Samples, reground and stored aerobically after periods of anaerobic storage, were assayed for total aerobic bacterial counts, percentage of gram‐positive microflora, and pH. Lactic acid concentration ranged from 130 to 1055 mg per 100g ground beef and increased with anaerobic storage. During 6 days of aerobic storage, both increases and decreases in concentration were noted and related to changes in microbial flora. A positive correlation was found between the proportion of gram‐positive bacteria (lactic acid bacteria) and lactic acid and pH.

Quantitative vaginal microflora in women convalescent from toxic shock syndrome and in healthy controls.

We performed sequential and quantitative vaginal cultures obtained from 8 women within 4 days to 3 years (average, 15.8 months) after their recovery from classic menstrual toxic shock syndrome (TSS) and from 11 healthy women who served as age-matched controls. Apart from tampon use, which was significantly less frequent in TSS women after their acute illness, no demographic differences were observed in the two groups. Significantly lower total aerobic and anaerobic bacterial counts were found in TSS women than in healthy controls (P less than 0.05, Mann-Whitney test). These differences were most profound during the menstrual (aerobes) and premenstrual (aerobes and anaerobes) sample times, whereas no difference in bacterial counts was observed in the mid-cycle samples. Although the less frequent usage of tampons among TSS women after their acute illness might explain the lower aerobic counts in menstrual specimens, this is unlikely to explain the significantly lower aerobic and anaerobic counts observed in premenstrual samples when tampons were not used in either group. It is possible that these differences in the quantitative vaginal microflora were a direct result of recent TSS in these women. Alternatively, disruption of the normal indigenous microflora could have predisposed these women to acute TSS by alteration of the resistance of vaginal colonization to pathogenic microorganisms.

Automated Counting of Bacterial Colonies on Spread Agar Plates and Non-Gridded Membrane Filters

The Biotran II automated colony counter was compared with a manual procedure for accuracy in counting bacterial colonies using both spread agar plate and membrane filter techniques. Comparative total bacterial counts of 250 samples (14 food, 124 water and 112 raw milk) were analyzed using the spread agar plate technique. Compared to manual enumeration, the Biotran II was found to be inaccurate for counting bacterial colonies on spread agar plates. Only 60 (24%) and 79 (31.6%) Biotran II counts fell within 10 and 20%, respectively, of the corresponding manual counts. Two samples from each of three river and four effluent sources were analyzed for total aerobic, total coliform, fecal coliform, fecal streptococci and total staphylococci bacterial counts using non-gridded membrane filters. A yellow acetate filter was used to mask the background growth and enhance the target colonies on the membrane filter. However, the method had limited success. Only 12 (20.7%) and 20 (34.5%) Biotran II counts fell within 10 and 20%, respectively, of the corresponding manual counts. Until the effect of background growth can be eliminated, the Biotran II cannot be relied upon to accurately count bacterial colonies on membrane filters.

STORAGE STABILITY, PALATABILITY AND HISTOLOGICAL CHARACTERISTICS OF MECHANICALLY TENDERIZED BEEF STEAKS

ABSTRACTUSDA Choice and Utility grade boneless beef loins were used to determine the palatability, bacteriological and histological characteristics of steaks mechanically tenderized. There was a significant improvement in taste panel ratings of tenderness for the Utility tenderized steaks, but only a small improvement (P > 0.05) for the Choice tenderized steaks. None of the total aerobic bacterial surface counts or the interior counts for total aerobic, psychotropic or anaerobic bacteria was significantly different, between tenderized and nontenderized steaks compared at 1, 2, 5 and 10 days of storage at 5°C. Histological studies showed a definite pattern of blade penetrations in the tenderized samples at low magnifications. At very high magnifications, the muscle fibers were torn and fragmented by the blade rather than evenly cut.

MICROBIOLOGICAL CONDITION OF BROILERS AS INFLUENCED BY VACUUM AND CARBON DIOXIDE IN BULK SHIPPING PACKS

ABSTRACTBulk vacuum‐gas packs of broilers were examined microbiologically and organoleptically in tests to determine effects of storage temperature, film permeability, carbon dioxide level and vacuum level on acceptability and shelf‐life of fresh‐processed poultry. Total aerobic bacterial counts and off‐odor development were determined after 5–18 days of storage in bulk packs and again after 2–7 more days of storage in a retail case. Significantly lower microbial counts and extended shelf‐life were found when storage was at 2°C instead of 5°C, after 12 days storage when low permeable packaging film was used instead of high permeable film and after 15 days of storage when 65% CO2 was used instead of 20% CO2. No significant difference in microbial counts was found when a pinhole was made to simulate leaking or torn bulk packs. Gram stains of bacteria from total plate counts and type of off‐odor observed indicate spoilage of vacuum‐gas packaged broilers was caused by different bacteria than spoilage of ice‐packed broilers.

The use of chlorhexidine gluconate mouthrinses in patients with inter-maxillary fixation

A study was made of the potential value of a 0.2 per cent chlorhexidine gluconate mouthwash as an aid to oral hygiene in patients with inter-maxillary fixation. Total salivary aerobic and anaerobic bacterial counts were markedly and significantly reduced during hospitalisation in the patients using chlorhexidine, whereas saline was without effect. The plaque scores in the chlorhexidine group were significantly less than the saline group.

Nutritional Regime, Post-Slaughter Conditioning Temperature, and Vacuum Packaging Effects on Bacteriology of Beef Carcasses and Retail Meat Cuts

Thirty-eight crossbred steers were used to evaluate effects of nutritional regime (grass-, short-, long-, and forage-fed) and post-slaughter chilling (3 C) and conditioning temperature (13 C) on carcass psychrotrophic and mesophilic bacterial counts. Inside chucks from right halves of carcasses chilled at 3 C for 48 h were used to evaluate effects of nutritional regime and vacuum packaging on total aerobic and anaerobic bacterial counts. Psychrotrophic and mesophilic mean bacterial counts tended to decrease from 1 to 46 h postmortem regardless of temperature treatment. At 46 h postmortem, the forage-fed group mean psychrotrophic count was significantly lower (P < 0.05) than that for any of the other feeding regimes. Mesophilic mean counts were significantly different (P < 0.05) at 46 h postmortem (grass-fed >short-fed >long-fed > forage-fed). Carcass halves chilled at 3 C for 46 h had lower total psychrotrophic and mesophilic mean bacterial counts than did corresponding halves conditioned at 13 C for 8 h then chilled at 3 C for 38 h. Total aerobic and anaerobic counts tended to remain constant or decrease slightly during vacuum storage for 21 days at 0 to 1 C. Both aerobic and anaerobic counts on vacuum-stored cuts from carcasses of grass-fed steers were significantly higher (P < 0.05) than other feeding-regime means. Aerobic and anaerobic counts on vacuum-stored cuts from carcasses of short-, long-, and forage-fed steers were statistically similar. All carcass and inside-chuck bacterial counts were well within acceptable limits. Scalpel-template sampling was considered to be a significant improvement over previously used methods.

Dye Reduction Method for Estimating Bacterial Counts in Ground Beef

A dye reduction method was developed for estimating total aerobic and/or psychrotrophic bacterial counts in ground beef. The method is based on color changes in indicator disks placed on the meat surface.

Frozen Storage of Ground Turkey

Ground turkey was prepared from fresh turkeys and from turkeys that had been in frozen storage for six or ten months. The ground turkey was prepared commercially, packed in two types of plastic tubes that differed in oxygen permeability, and held at −12 to −29° C. for two, four, and eight months. None of these variables affected the peroxide value, color or odor of the products when tested immediately after storage. The flavor and the total aerobic bacterial count varied slightly but not in a consistent pattern that could be related to the variables. Samples of products after frozen storage were reground and held refrigerated for three days under simulated market condition. One lot that had been prepared from frozen turkeys supported more microbial growth under these conditions than did its counterpart that had been made from fresh turkeys. In general, the stability of the ground turkey under simulated market conditions was not significantly affected by the imposed experimental variables. This study supports the view that turkey can be held in coarse-ground form at freezer temperatures for at least 6 months as a means of supply control. However, it is implicit in these conclusions that the turkeys, whether fresh or frozen, must be processed and stored using good manufacturing practices.

Effect of changing intestinal bacterial flora on thyroid function in the rat.

Experiments were designed to determine if changes in rat intestinal bacterial flora are accompanied by changes in thyroid function. Attempts to modify intestinal bacterial flora of Sprague-Dawley (SD) rats were made by (a) feeding the non-orally absorbed antibiotic, kanamycin; (b) insanitary caging. Thyroid function was also compared in germfree and ex-germ-free animals. Qualitative and quantitative studies of intestinal bacteria were carried out concurrently; at the end of each study thyroidal radioactive iodine (RAI) uptakes and plasma radioactivities were determined at three or 24 hours after radioiodine (Na131I) was administered. Thyroid glands were weighed and total iodine concentration was measured as well as plasma protein-bound iodine (PBI). Kanamycin lowered the total aerobic and anaerobic bacterial counts of female rats and this was accompanied by reduced three hours thyroidal RAI uptakes after 42 and 72 days of treatment Insanitary caging for four or eight weeks did not change intestinal bacterial flora and there were no differences in thyroid function. Female germ-free animals had significantly smaller thyroids than conventional female rats. These studies have shown that reduction in the intestinal bacterial flora may affect thyroid function - simulating modest supplementation with iodine.

EFFECT OF FREEZING AND PACKAGING METHODS ON SURVIVAL AND BIOCHEMICAL ACTIVITY OF SPOILAGE ORGANISMS ON CHICKEN

SUMMARY— A study was conducted to determine effects of freezing, thawing, and subsequent holding at about 5°C on survival or growth of aerobic bacteria on chicken packaged with various materials. Production of fluorescent pigment, and extracellular proteinase and lipase activities were used as indices of the ability of the organisms to produce spoilage. Growth of bacteria was determined by colony counts. Assays for proteolysis were made by means of a dye binding method; lipolysis of chicken fat was determined by titration of free fatty acids. Fluorescent pigment formation was evaluated by means of a photofluorometer. The influence of availability of oxygen on proteolytic and lipoytic spoilage of poultry was studied after chicken was packaged with materials having high or low oxygen permeability and by vacuum packaging. Fluorescent pigment production, proteofytic and lipolytic spoilage of chicken stored at 5°C was directly related to the availability of oxygen provided by the packaging procedure. Bacterial numbers paralleled increases in biochemical indices of deterioration. Freezing of chicken at −29°C for 35 days followed by defrosting and refrigerated storage increased the proportion of biochemically active psychrophiles on the surface of the meat. Vacuum packaging generally limited amount of spoilage as measured by the criteria specified. When samples were analyzed after alternate freezing and thawing, total aerobic bacterial counts were only slightly different from those on chicken frozen continuously for 22‐25 days.

Almond harvesting, processing, and microbial flora.

This survey was set up on a statistical sampling plan to determine the microbial quality of almonds as they are received at the processing plant. The total aerobic bacterial count and yeast and mold count distribution were skewed by a few high counts compared with the majority of relatively low counts. Hard shell varieties of almonds had lower counts than did soft shell, and almonds with complete shells had lower counts than shelled almonds. Almonds harvested onto canvas had lower counts than those harvested by knocking onto the ground. Nuts with the least amounts of foreign material mixed into the sample had the lowest counts, as did nuts with the least amount of insect damage. Coliforms, Escherichia coli, and Streptococcus were isolated from the nuts, and their presence was correlated with soil contamination. When almonds are stored, the total plate count, the Streptococcus count, and the E. coli count after an initial drop remain nearly constant for more than 3 months. In addition to the indicator organisms, several genera of bacteria were isolated including Bacillus, Xanthomonas, Achromobacter, Pseudomonas, Micrococcus or Staphylococcus, and Brevibacterium.

EFFECT OF PROCESSING AND STORAGE CONDITIONS ON THE MICROFLORA OF CLOSTRIDIUM PERFRINGENS‐INOCULATED FRANKFURTERS

SUMMARY: The growth support potential of frankfurters for Clostridium perfringens was determined. Inoculated emulsions were stuffed into glass tubes and processed so that they reached an internal temperature of 68–69°C in 30–48 min. The tubes were sealed with agar plugs and rubber stoppers to simulate vacuum‐packaging conditions. Total aerobic and anaerobic bacterial counts in uninoculated raw emulsion were 1 to 3 log cycles higher when petri dishes were incubated at 23°C as opposed to 37°C. The low‐temperature‐growing mesophiles and psychrotrophs were destroyed during processing. The 37°C counts were reduced 1 log cycle and the 23°C counts, 2 to 3 log cycles. Clostridium perfringens reproduced rapidly in frankfurters at 37 and 23°C, more slowly at 15 and 12°C, and not at all during 2 wk of storage at 10° or 4 wk at 0–5°C. Clostridium perfringens made up 2.5–10% of the total anaerobic count at 0 time but became the dominant organism during the storage at all temperatures permitting growth.

Almond Harvesting, Processing, and Microbial Flora

This survey was set up on a statistical sampling plan to determine the microbial quality of almonds as they are received at the processing plant. The total aerobic bacterial count and yeast and mold count distribution were skewed by a few high counts compared with the majority of relatively low counts. Hard shell varieties of almonds had lower counts than did soft shell, and almonds with complete shells had lower counts than shelled almonds. Almonds harvested onto canvas had lower counts than those harvested by knocking onto the ground. Nuts with the least amounts of foreign material mixed into the sample had the lowest counts, as did nuts with the least amount of insect damage. Coliforms, Escherichia coli, and Streptococcus were isolated from the nuts, and their presence was correlated with soil contamination. When almonds are stored, the total plate count, the Streptococcus count, and the E. coli count after an initial drop remain nearly constant for more than 3 months. In addition to the indicator organisms, several genera of bacteria were isolated including Bacillus, Xanthomonas, Achromobacter, Pseudomonas, Micrococcus or Staphylococcus, and Brevibacterium.

Microbiological quality of protein feed supplements produced by rendering plants.

Samples of protein feed supplements produced by rendering plants were examined for salmonellae, total aerobic bacterial counts, coliform counts, and enterococci. Isolations of salmonellae were more frequent from products with high counts; however, 6% of the samples with total counts of less than 1,000 per gram and 14% of the samples with coliform counts of less than 1 per gram contained salmonellae. Serotypes of Escherichia coli which have been associated with disease in domestic animals and poultry were also isolated from products. Although the distribution of serotypes of salmonellae isolated from environmental swabs and flies was similar to that isolated from products, the isolation of several serotypes from flies which had not been isolated in plants suggested that flies may be a potential source of contamination.

Microbiological Quality of Protein Feed Supplements Produced by Rendering Plants1

Samples of protein feed supplements produced by rendering plants were examined for salmonellae, total aerobic bacterial counts, coliform counts, and enterococci. Isolations of salmonellae were more frequent from products with high counts; however, 6% of the samples with total counts of less than 1,000 per gram and 14% of the samples with coliform counts of less than 1 per gram contained salmonellae. Serotypes of Escherichia coli which have been associated with disease in domestic animals and poultry were also isolated from products. Although the distribution of serotypes of salmonellae isolated from environmental swabs and flies was similar to that isolated from products, the isolation of several serotypes from flies which had not been isolated in plants suggested that flies may be a potential source of contamination.

AIRBORNE MICROORGANISMS IN BROILER PROCESSING PLANTS.

Concentrations of total aerobic bacteria, molds, yeasts, coliforms, enterococci, and psychrophiles were determined in the air of two poultry processing plants with Andersen samplers and a mobile power supply. Total aerobic bacterial counts were highest in the dressing room, with diminishing numbers in the shackling, eviscerating, and holding rooms, when sampling was carried out during plant operation. The average counts per ft(3) of air in these four rooms were 2,200; 560; 230; and 62, respectively. (Each value is the average of 36 observations.) The number of organisms increased in the shackling and dressing rooms once processing was begun. Average total aerobic bacterial counts increased from 70 to 870 to 3,000 in the shackling room and from 310 to 4,900 to 7,000 in the dressing room when sampling was carried out at 5:00 am (before plant operations), 9:00 am, and 2:00 pm, respectively. (Each value is the mean of 12 observations.) Airborne molds might originate from a source other than the poultry being processed.

Airborne Microorganisms in Broiler Processing Plants

Concentrations of total aerobic bacteria, molds, yeasts, coliforms, enterococci, and psychrophiles were determined in the air of two poultry processing plants with Andersen samplers and a mobile power supply. Total aerobic bacterial counts were highest in the dressing room, with diminishing numbers in the shackling, eviscerating, and holding rooms, when sampling was carried out during plant operation. The average counts per ft(3) of air in these four rooms were 2,200; 560; 230; and 62, respectively. (Each value is the average of 36 observations.) The number of organisms increased in the shackling and dressing rooms once processing was begun. Average total aerobic bacterial counts increased from 70 to 870 to 3,000 in the shackling room and from 310 to 4,900 to 7,000 in the dressing room when sampling was carried out at 5:00 am (before plant operations), 9:00 am, and 2:00 pm, respectively. (Each value is the mean of 12 observations.) Airborne molds might originate from a source other than the poultry being processed.