Fate of Selected Bacterial Pathogens and Indicators in Fractionated Poultry Litter During Storage.

A study of broiler litter re-utilization potential was conducted with the goal of determining if storage of litter significantly reduced potential pathogens to levels safe for re-utilization. Litter from four broiler houses was separated into a fine fraction for fertilizer use and a coarse fraction for use as a supplement to wood shavings in growing subsequent flocks of birds. Fractions and whole litter were stored in indoor piles for four months with periodic analysis for culturable pathogenic and indicator bacteria. Significant reductions in microbial concentrations occurred in a majority of samples tested during four months of storage (in most cases to below detection limits of approximately 30 CFU/g dry weight). Poultry feed was found to be one possible source of litter contamination.

Cytotoxicity and Antibiotic Resistance Profiles of Aeromonas hydrophila Isolates From a Broiler Processing Operation.

The cytotoxicity and antibiotic resistance profiles of Aeromonas hydrophila isolates recovered from broiler carcasses and chill water samples taken from a Georgia processing plant were determined. Carcasses were sampled at pre- and post-evisceration locations, immediately after immersion chilling, and after being boxed, iced and refrigerated for 48 h. Grab samples of chill water were randomly selected for A. hydrophila recovery. Resistance of isolates to nine antibiotics was determined with the Bauer disc diffusion method (i.e., to ampicillin, cephalothin, streptomycin, kanamycin, chloramphenicol, naladixic acid, tetracycline, neomycin, and gentamicin). Multiple antibiotic resistance occurred in 46.2% of 119 isolates. The majority of the multiple antibiotic-resistant isolates (76.4%) were resistant only to ampicillin and cephalothin. The remaining multiple antibiotic-resistant isolates (23.6%) were resistant to various combinations of 2, 3, or 4 antibiotics, most of which were recovered from carcasses immediately after evisceration. Cytotoxin activity was detected in 63.8% of all isolates using the Y-1 mouse adrenal tumor cell line. Cytotoxin positive isolates were recovered from all sampling locations including chill water. The highest cytotoxicity titers were shown among isolates recovered from carcasses immediately after evisceration. These data suggest bird fecal contamination as an important source of A. hydrophila in broilers and broiler processing plants rather than environmental contamination.

Prevalence of Salmonella enteritidis and Other Serovars in Ovaries of Layer Hens at Time of Slaughter.

Ovaries aseptically collected from commercial layer hens at time of slaughter were assayed for Salmonella as an indication of systemic infection of birds within a flock. Birds were randomly selected at the time of slaughter from 42 flocks from seven southeastern states and Pennsylvania. Ovaries were pooled, four per pool, mascerated, and Salmonella , isolates were recovered by conventional methods. Thirty-two of 42 flocks (76.2%) were positive at >10% infection rate based on sampling methods. Fifteen different serovars were detected in flocks. Salmonella heidelberg was the predominant serovar, representing 56.5% of the salmonellae detected. However, S. agona , S. oranienburg , S. mbandaka , S. kentucky , S. montevideo , S. london , S. typhimurium , S. infantis , S. schwarzenqrund , S. ohio , S. cerro , S. anatum , and Salmonella untypeable were also found. S. enteritidis , phage type 23 was recovered from only one (2.4%) of the flocks. Single and multiple serovar infections were found with up to five serovars recovered from a single flock. Twenty-one positive flocks (50%) were positive with a single Salmonella serovar; of these S. heidelberg represented 76.2%. An overall mean of 26.6% of the pooled ovary samples within each infected flock was positive for salmonellae, with an overall range of 0-100%. The significance of Salmonella serovars other than S. enteritidis found at the levels reported has yet to be determined.

Recovery of Aeromonas hydrophila from Carcasses and Processing Water in a Broiler Processing Operation.

Aeromonas hydrophila , a potential pathogen associated with cases of human diarrhea, was enumerated using a rinse method on broiler carcasses and in processing water at selected locations in a commercial processing plant. A. hydrophila was detected on 98% of all carcasses tested, and 92% of all chill water samples; scald and rinse water samples were negative for this organism. Mean numbers on carcasses ranged for 28 CFU/ml of rinse fluid, detected immediately after the chiller, to 580 CFU/ml of rinse fluid at the post-evisceration stage. Water chilling and washing resulted in a significant reduction in A. hydrophila numbers on carcasses, while refrigerated storage (48 h) resulted in a significant increase. Data suggest that isolates recovered from carcasses may likely have been of intestinal origin and that the evisceration step was a probable cause of contamination. A. hydrophila levels on carcasses and processing waters showed no correlation to other bacteriological parameters which might be used in a process evaluation program.

Thermal Destruction of Escherichia coli and Klebsiella pneumoniae in Human Milk.

A continuous flow high-temperature short-time pasteurization system was used to determine kinetic parameters (D- and z-values) for thermal destruction of the bacterial pathogens, Escherichia coli and Klebsiella pneumoniae , in mature human milk. D-and z-alues of each bacterium were determined from data on survivors enumerated on both selective media, Violet Red Bile agar or MacConkey's, and on a non-selective medium, nutrient agar (NA). For E. coli , D-values were determined at 58, 60, 62 and 64°C. The predicted value of D at 60°C is 31.5 s. The z-value for E. coli is 3.2°C. D-values for K. pneumoniae were determined at 52, 56 and 58°C. Based on these data the predicted value of D at 60°C is 1.3 s. The z-value for K. pneumoniae , is 2.8°C. For both E. coli and K. pneumoniae , counts on NA tend to be higher than on selective media. This is undoubtedly due to the inhibitory nature of the selective media. This also suggests that some degree of thermal injury may occur for each organism.

Bacteriological Profiles of Human Milk from Individual Donors and Pooled Samples from a Commercial Milk Bank.

The bacteriological profiles of human milk samples collected from individual donors under supervised conditions of collection were compared to pooled human milk samples obtained from a commercial human milk bank. Total aerobic counts and total coliform counts of individual donor samples were lower than those of pooled, banked human milk. All of the 200 isolates from ten individual samples were staphylococci with Staphylococcus epidermidis predominating (82%). Only 1% of the isolates was identified as Staphylococcus aureus . Forty-two percent of the 100 isolates from five pooled samples were staphylococci and all of these staphylococci were coagulase-negative. Three percent of the isolates from the pooled samples were Streptococcus faecalis . The remainder (55%) were gram-negative organisms. S. epidermidis was the microorganism that was isolated most frequently from either individual (9 of 10) or pooled (3 of 5) samples.

Thermal Destruction of Staphylococcus aureus in Human Milk.

Rates of thermal destruction of Staphylococcus aureus were determined in mature human milk using a continuous flow high-temperature short-time pasteurization system. D and z values for inactiviation of S. aureus were determined from data on survivors capable of forming colonies in an appropriate selective medium. The effects of thermal injury on D and z values were assessed by survivor colony forming units (CFU) on Staphylococcus medium 110 (SMI 10), nutrient agar (NA), Trypticase Soy Agar (TSA), Trypticase Soy Agar with 7.5% NaCi (TSAS) and Baird-Parker medium (BP) (Difco Laboratories, Detroit, MI). D values for inactivation of S. aureus at 52, 58 and 60 and 62°C were used to predict D at 60°C of 15.3 s and 24.3 s when based on survivor CFU in SM 110 and nutrient agar, respectively. The z value was 4.9°C in either medium. D-values for inactivation of S. aureus at 60, 62, 64 and 67°C were used to predict D at 60°C of 41.2 s, 41.0 s and 34.7 s when based on survivor CFU in BP, TSA and TSAS, respectively. The z values were 6.5, 6.5 and 6.4°C, respectively.

IgA, IgG, IgM and Lactoferrin Contents of Human Milk During Early Lactation and the Effect of Processing and Storage.

The total IgA, IgG, IgM and lactoferrin concentrations in human milk from 89 donors were studied at three lactational stages: early transitional (3 to 8 d postpartum), transitional (10 to 14 d postpartum) and mature (30 to 47 d postpartum). The effects of processing and storage on these components in composite samples of mature human milk were determined. There were no significant diurnal variations in any of the four protective factors at either the transitional or mature stages. Concentrations of total IgA, IgM and lactoferrin decreased significantly as time postpartum increased, whereas the IgG content showed no significant changes. The total IgA, IgM and lactoferrin levels were significantly decreased by all heat treatments (62.5°C for 30 min, 72°C for 15 s, 88°C for 5 s, and 100°C for 5 min). Heating at 62.5°C for 30 min did not affect the IgG content; however, the other heat treatments significantly reduced IgG concentration. At the times and temperatures selected for this study, the two lower temperature treatments were less detrimental to the protective factors than the higher temperature treatments.