Impact of Poultry Processing Operating Parameters on Bacterial Transmission and Persistence on Chicken Carcasses and Their Shelf Life

It is important for the poultry industry to maximize product safety and quality by understanding the connection between bacterial diversity on chicken carcasses throughout poultry processing to the end of shelf life and the impact of the local processing environment. Enumeration of total aerobic bacteria, Campylobacter and Pseudomonas, and 16S rRNA gene amplicon sequencing were used to evaluate the processing line by collecting 10 carcasses from five processing steps: prescald, postplucker, pre- and post-immersion chill, and post-air chill. The diversity throughout a 12-day shelf life was also determined by examining 30 packaged carcasses. To identify the sources of possible contamination, scald water tank, immersion chilling water tank, air samples, and wall surfaces in the air-chill room were analyzed. Despite bacterial reductions on carcasses (>5 log10 CFU/ml) throughout the process, each step altered the bacterial diversity. Campylobacter was a minor but persistent component in the bacterial community on carcasses. The combination of scalding, defeathering, and plucking distributed thermophilic spore-forming Anoxybacillus to carcasses, which remained at a high abundance on carcasses throughout subsequent processes. Pseudomonas was not isolated from carcasses after air chilling but was abundant on the wall of the air-chill room and became the predominant taxon at the end of shelf life, suggesting possible contamination through air movement. The results suggest that attention is needed at each processing step, regardless of bacterial reductions on carcasses. Changing scalding water regularly, maintaining good hygiene practices during processing, and thorough disinfection at the end of each processing day are important to minimize bacterial transmission.IMPORTANCE Culture-based and culture-independent approaches were utilized to reveal bacterial community changes on chicken carcasses at different processing steps and potential routes from the local processing environment. Current commercial processing effectively reduced bacterial loads on carcasses. Poultry processes have similar processes across facilities, but various processing arrangements and operating parameters could impact the bacterial transmission and persistence on carcasses differently. This study showed the use of a single tunnel incorporating scalding, defeathering and plucking may undesirably distribute the thermoduric bacteria, e.g., Campylobacter and Anoxybacillus, between the local environment and carcasses, whereas this does not occur when these steps are separated. The length of immersion and air chilling also impacted bacterial diversity on carcasses. Air chilling can transfer Pseudomonas from wall surfaces onto carcasses; this may subsequently influence chicken product shelf life. This study helps poultry processors understand the impact of current commercial processing and improve the chicken product quality and safety.

National Survey of Shiga Toxin-Producing Escherichia coli Serotypes O26, O45, O103, O111, O121, O145, and O157 in Australian Beef Cattle Feces

Escherichia coli O157 and six non-O157 Shiga toxin-producing E. coli (STEC) serotypes (O26, O45, O103, O111, O121, and O145, colloquially referred to as the "big 6") have been classified as adulterants of raw nonintact beef products in the United States. While beef cattle are a known reservoir for the prototype STEC serotype, E. coli O157, less is known about the dissemination of non-O157 STEC serotypes in Australian cattle. In the present study, 1,500 fecal samples were collected at slaughter from adult (n =628) and young (n =286) beef cattle, adult (n =128) and young (n =143) dairy cattle, and veal calves (n = 315) across 31 Australian export-registered processing establishments. Fecal samples were enriched and tested for E. coli O157 and the big 6 STEC serotypes using BAX System PCR and immunomagnetic separation methods. Pathogenic STEC (pSTEC; isolates that possess stx, eae, and an O antigen marker for O157 or a big 6 serotype) were isolated from 115 samples (7.7%), of which 100 (6.7%) contained E. coli O157 and 19 (1.3%) contained a big 6 serotype. Four of the 115 samples contained multiple pSTEC serotypes. Among samples confirmed for big 6 pSTEC, 15 (1%) contained E. coli O26 and 4 (0.3%) contained E. coli O111. pSTEC of serotypes O45, O103, O121, and O145 were not isolated from any sample, even though genes indicative of E. coli belonging to these serotypes were detected by PCR. Analysis of animal classes revealed a higher pSTEC prevalence in younger animals, including veal (12.7%), young beef (9.8%), and young dairy (7.0%), than in adult animals, including adult beef (5.1%) and adult dairy (3.9%). This study is the largest of its kind undertaken in Australia. In contrast to E. coli O157 and consistent with previous findings, this study reports a relatively low prevalence of big 6 pSTEC serotypes in Australian cattle populations.

Prevalence and Antimicrobial Resistance of Salmonella and Escherichia coli from Australian Cattle Populations at Slaughter

Antimicrobial agents are used in cattle production systems for the prevention and control of bacteria associated with diseases. Australia is the world's third largest exporter of beef; however, this country does not have an ongoing surveillance system for antimicrobial resistance (AMR) in cattle or in foods derived from these animals. In this study, 910 beef cattle, 290 dairy cattle, and 300 veal calf fecal samples collected at slaughter were examined for the presence of Escherichia coli and Salmonella, and the phenotypic AMR of 800 E. coli and 217 Salmonella isolates was determined. E. coli was readily isolated from all types of samples (92.3% of total samples), whereas Salmonella was recovered from only 14.4% of samples and was more likely to be isolated from dairy cattle samples than from beef cattle or veal calf samples. The results of AMR testing corroborate previous Australian animal and retail food surveys, which have indicated a low level of AMR. Multidrug resistance in Salmonella isolates from beef cattle was detected infrequently; however, the resistance was to antimicrobials of low importance in human medicine. Although some differences in AMR between isolates from the different types of animals were observed, there is minimal evidence that specific production practices are responsible for disproportionate contributions to AMR development. In general, resistance to antimicrobials of critical and high importance in human medicine was low regardless of the isolate source. The low level of AMR in bacteria from Australian cattle is likely a result of strict regulation of antimicrobials in food animals in Australia and animal management systems that do not favor bacterial disease.

Prevalence and concentration of Arcobacter spp. on Australian Beef Carcasses

The International Commission on Microbiological Specifications for Foods (ICMSF) classified Arcobacter spp. as emerging pathogens in 2002. Arcobacter spp. have been isolated from numerous food products at retail and from animal carcasses and feces at slaughter. A survey was conducted to determine both the prevalence and concentration of Arcobacter spp. on pre-chill beef carcasses. Surface swab samples were collected from 130 beef carcasses at the end of processing, prior to chilling. The concentration of Arcobacter spp. was determined by a most-probable-number per square centimeter (3 by 3) method with a limit of detection of 0.12 CFU/cm(2). Of the 100 carcasses examined from export abattoirs, 20 (20.0%) were contaminated with Arcobacter spp., and 5 of these had quantifiable levels of contamination ranging from 0.12 to 0.31 CFU/cm(2). Of the 30 carcasses examined at a pet food abattoir, 25 (83.3%) were contaminated with Arcobacter spp., and 10 of these had quantifiable levels of contamination ranging from 0.12 to 0.95 CFU/cm(2). Three species of Arcobacter, A. butzleri, A. cryaerophilus, and A. skirowii, were identified by PCR. Each of the species was present in an approximately equal ratio from export abattoirs. This study demonstrates that slaughter practices at export abattoirs are sufficient to maintain both low prevalence and low levels of contamination of beef carcasses with Arcobacter spp.

Relative prevalence of Salmonella Sofia on broiler chickens pre- and postprocessing in Australia

A survey was conducted to determine the relative prevalence of Salmonella serovars on whole chicken carcasses before and after processing in 3 Australian poultry abattoirs. Ninety and 180 whole chicken carcasses were tested for Salmonella serovars before and after processing, respectively. Each carcass was subjected to a buffered peptone water rinse according to Australian Standard methodologies and Salmonella prevalence was determined using Australian Standard methodologies. After isolation, Salmonella isolates were serotyped and results were analyzed to determine the relative percentage of each serovar at both processing points. Salmonella Sofia was shown to significantly increase its relative prevalence (P < or = 0.05) after processing and proved to be the dominant serovar accounting for 45/89 (51%) isolations before processing and 51/69 (74%) isolations after processing. The reasons for the increased relative prevalence of Salmonella Sofia are currently unknown and require further investigation but may involve factors related to prevalence and numbers on chickens and the ability of Salmonella Sofia to respond to environmental stressors and attach to surfaces.

The ability of Campylobacter jejuni cells to attach to stainless steel does not change as they become nonculturable

The ability of Campylobacter jejuni strains to attach to stainless steel as they became nonculturable during storage in distilled water at 4 degrees C for 30 days was investigated. From an initial count of approximately 7 log colony-forming units/mL all strains completely lost culturability by day 20, but the numbers of cells attaching to stainless steel remained constant at approximately 3.5 log cells/cm(2). These findings suggest that viable but nonculturable Campylobacter in a liquid matrix can still attach to stainless steel.

Dexamethasone facilitates discharge after outpatient anorectal surgery

Corticosteroids can decrease pain and postoperative nausea and vomiting after ambulatory surgery. Therefore, we designed a study to evaluate if the routine use of dexamethasone would facilitate the early recovery process after anorectal surgery. A secondary aim of the study was to determine if dexamethasone would increase the incidence of postoperative wound complications. Eighty adult outpatients undergoing anorectal surgery with a standardized monitored anesthesia care technique were randomly assigned to receive either dexamethasone 4 mg IV or an equal volume of saline before the start of surgery. All patients were premedicated with midazolam 2 mg IV and received ketorolac 30 mg IV as a preemptive analgesic. A propofol infusion, 50 microg. kg(-1). min(-1) IV, was initiated and subsequently titrated to maintain an observer's assessment of alertness/sedation score of 2 or 3 (with 5 = awake/alert to 1 = asleep). Fentanyl 25 microg IV was administered 3-5 min before infiltrating the surgical field with a 30-mL local anesthetic mixture containing 15 mL of lidocaine 1% and 15 mL of bupivacaine 0.25% (with epinephrine 1:200,000 and sodium bicarbonate 3 mL). All patients were fast-tracked directly from the operating room to the step-down recovery area. Even though the incidences of postoperative pain and postoperative nausea and vomiting were small in both treatment groups, the time to "home readiness" was significantly shorter in the dexamethasone group. Importantly, there was no increase in the incidence of wound infections (8% vs 12%) or hematoma formation (3% vs 5%) in the dexamethasone (versus saline) group. We conclude that the administration of dexamethasone, 4 mg IV, shortened the time to home readiness without increasing the incidence of postoperative wound infections in a high-risk outpatient population undergoing anorectal surgery.

IMPLICATIONS

A single dose of dexamethasone (4 mg IV) decreased the time to "home readiness" without increasing the incidence of postoperative wound complications in an outpatient population undergoing anorectal surgery.

Acid resistance of enterohaemorrhagic and generic Escherichia coli associated with foodborne disease and meat

As part of the Australia New Zealand Food Authorities (ANZFA) food standards code, salami manufacturers are required to demonstrate that their process is capable of achieving a 3-log reduction in Escherichia coli. Non-pathogenic E. coli strains with similar or greater acid resistance to enterohaemorrhagic E. coli (EHEC) are needed if industry is to conduct challenge studies to demonstrate compliance with the standard. In the present study, E. coli isolates from sheep and beef carcasses and meat were shown to have wide-ranging acid resistance in broth when preadapted to growth in acidic conditions. Times required for a 3-log reduction in E. coli ranged from less than I day to more than 28 days. Variable acid resistance was observed in both EHEC strains associated with foodborne outbreaks and generic E. coli strains. Generic E. coli strains with the greatest acid resistance were assessed for pathogenicity markers and their survival in fermented meat compared with EHEC strains. It was demonstrated that generic E. coli strains could be used for challenge studies to determine compliance with or validate performance standards designed for the control of EHEC.

Spontaneous recovery profile of rapacuronium during desflurane, sevoflurane, or propofol anesthesia for outpatient laparoscopy

We evaluated the spontaneous recovery characteristics of rapacuronium during desflurane-, sevoflurane-, or propofol-based anesthesia in 51 consenting women undergoing laparoscopic tubal ligation procedures. After the induction of the anesthesia with standardized doses of propofol and fentanyl, 1.5 mg/kg IV rapacuronium was administered to facilitate tracheal intubation. Patients were randomized to receive either 1 minimum alveolar anesthetic concentration of desflurane, 1 minimum alveolar concentration of sevoflurane, or 100 microg. kg(-1). min(-1) propofol infusion in combination with 66% nitrous oxide in oxygen for maintenance of anesthesia. Neuromuscular blockade was monitored at the wrist by using electromyography. The degree of maximum blockade and the times for first twitch recovery (T(1)) to 5%, 25%, 50%, 75%, and 90%, as well as the recovery index, were similar in all three anesthetic groups. However, recovery times for the train-of-four ratio to achieve 0.7 and 0.8 were significantly longer with desflurane (44.4 +/- 18.9 and 53.5 +/- 22.4 min) and sevoflurane (44.8 +/- 15.1 and 53.2 +/- 15.8 min) compared with propofol (31.8 +/- 5.3 and 36.5 +/- 6.5 min). Eight patients (16%) required a maintenance dose of 0.5 mg/kg rapacuronium and reversal of rapacuronium residual block occurred in three (6%) patients. We conclude that spontaneous recovery after an intubating dose of 1.5 mg/kg rapacuronium was significantly prolonged by both desflurane and sevoflurane compared with propofol-based anesthesia. Routine monitoring of neuromuscular activity is recommended even when a single bolus dose of rapacuronium is administered during ambulatory anesthesia.

IMPLICATIONS

When administered for laparoscopic surgery, the duration of action of an intubating dose of rapacuronium was prolonged 40%-50% by desflurane and sevoflurane, respectively, (versus propofol). Monitoring recovery of neuromuscular blockade produced by rapacuronium is particularly important when desflurane or sevoflurane is administered to ensure that an adequate recovery (train-of-four > or = 0.8) is achieved by the end of anesthesia.

Onset/offset characteristics and intubating conditions of rapacuronium: a comparison with rocuronium

We compared onset and offset of action and tracheal intubating conditions after rapacuronium and rocuronium in 60 patients in a randomized, assessor-blinded study. Following induction of anaesthesia with propofol 2.5 mg kg-1, either rapacuronium 1.5 mg kg-1 (n = 30) or rocuronium 0.6 mg kg-1 (n = 30) was administered to facilitate tracheal intubation. Anaesthesia was maintained with either a propofol infusion (100 micrograms kg-1 min-1) or sevoflurane (1% end-tidal) with 66% nitrous oxide (N2O), n = 15 in each subgroup. Neuromuscular monitoring was performed using an electromyographic (EMG) device (Datex Relaxograph). The lag times (mean 42 (SD 11) s and 44 (16) s), maximum block (99 (2)% and 98 (3)%) and intubating conditions at 60 s (good-to-excellent in 86% and 84% of patients) were similar for rapacuronium and rocuronium, respectively. The onset time of rapacuronium was shorter than rocuronium (87 (20) vs 141 (65) s, P < 0.001), and the degree of block at 60 s was greater (69 (26) vs 50 (27)%, P < 0.05). Twenty-five per cent recovery was shorter with rapacuronium than rocuronium during propofol (15.0 (3.2) vs 39.1 (14.2) min, P < 0.001) and sevoflurane (15.1 (4.2) vs 47.8 (19.0) min, P < 0.001) anaesthesia. We conclude that rapacuronium 1.5 mg kg-1 had a more rapid onset, similar intubating conditions, and shorter recovery times than rocuronium 0.6 mg kg-1.

Fast-tracking after immersion lithotripsy: general anesthesia versus monitored anesthesia care

Both monitored anesthesia care (MAC) and general anesthesia (GA) offer advantages over epidural anesthesia for immersion lithotripsy. We compared propofol-based MAC and desflurane-based GA techniques for outpatient lithotripsy. After receiving midazolam 2 mg IV, 100 subjects were randomly assigned to one of two anesthetic treatment groups. In the MAC group, propofol 50-100 microg. kg(-1). min(-1) IV was titrated to maintain an observer's assessment of alertness/sedation score of 2-3 (5 = awake/alert to 1 = asleep). Remifentanil 0.05 microg.kg(-1). min(-1) IV supplemented with 0.125 microg/kg IV boluses, was administered for pain control. In the GA group, anesthesia was induced with propofol 1.5 mg/kg IV and remifentanil 0.125 microg/kg IV and maintained with desflurane (2%-4% inspired) and nitrous oxide (60%). Tachypnea (respiratory rate >20 breaths/min) was treated with remifentanil 0.125 microg/kg IV boluses. In the GA group, droperidol (0.625 mg IV) was administered as a prophylactic antiemetic. Recovery times and postoperative side effects were assessed up to 24 h after the procedure. Compared with MAC, the use of GA reduced the opioid requirement and decreased movements and episodes of desaturation (<90%) during the procedure. Although the GA group took longer to return to an observer's assessment of alertness/sedation score of 5, discharge times were similar in both groups. We conclude that GA can provide better conditions for outpatient immersion lithotripsy than MAC sedation without delaying discharge.

IMPLICATIONS

A desflurane-based general anesthetic technique using the cuffed oropharyngeal airway device was found to be a highly acceptable alternative to propofol-based monitored anesthesia care sedation for outpatient immersion lithotripsy.

Growth of Listeria monocytogenes on vacuum-packed cooked meats: effects of pH, aw, nitrite and ascorbate

Slices of cooked meats were inoculated with Listeria monocytogenes strain Murray B, vacuum-packed and stored at either 0 or 5 degrees C. Decreases in pH (6.9-5.9) and aw (0.993-0.960; adjusted with sodium chloride) of the cooked meats increased the lag time and reduced the growth rate at 5 degrees C. The type of meat (beef, pork, chicken or turkey) had no effect on the growth of the organism after allowance was made for pH. Sodium tripolyphosphate (0.3%) increased growth by increasing the pH of the cooked meat. Sodium nitrite reduced the growth rate and increased the lag time. Three microM of residual undissociated nitrite doubled the time taken for a 3 log increase in numbers of L. monocytogenes. The effectiveness of nitrite was significantly increased by sodium ascorbate (0.042%). In the absence of nitrite, ascorbate had no detectable effect on growth. The extent of growth at 0 degree C was similarly influenced by the interaction of pH, aw, nitrite and ascorbate, and was considerably less than at 5 degrees C. Quadratic equations were developed to describe some of the combined effects of pH, aw and residual nitrite on lag, growth rate and time for a 3 log increase in numbers of L. monocytogenes.