Associations between memory performance and Bifidobacterium pseudolongum abundance in the canine gut microbiome.

Memory has been identified as the least heritable cognitive trait in canines, suggesting a significant influence of non-genetic factors. We observed a trend that overall memory scores (OMS) improve with age in a cohort of 27 young dogs, but considerable plasticity exists. Employing linear discriminant analysis of gut microbiome data from dogs exhibiting low and high OMS, a single bacterial species, Bifidobacterium pseudolongum, was identified and confirmed to be correlated with elevated OMS. Subsequent analysis using a random forest regression model revealed that sex, litter, and breed identity had minimal predictive importance. Age had some predictive value but failed to achieve statistical significance in this dataset. In sharp contrast, the abundance of 17 bacterial taxa in the microbiome showed a stronger predictive capacity for memory performance. Our findings provide insights into microbiome underpinnings of mammalian cognitive functions and suggest avenues for developing psychobiotics to enhance canine memory and learning.

Quantification of Salmonella Infantis transfer from transport drawer flooring to broiler chickens during holding.

Transportation is a potential point of cross-contamination before broiler chickens arrive at the processing plant for slaughter. Previous studies have associated the use of uncleaned transport containers with the introduction of pathogenic bacteria onto uncontaminated broilers. The objective of this study was to quantify the transfer of Salmonella from transport drawer perforated flooring to broiler chickens during different holding times. For traceability, the flooring of each drawer was inoculated with fecal content slurry containing a marker strain of Salmonella Infantis. Three drawers per treatment were used, and each drawer was subjected to one of the following treatments: pressure wash, disinfectant, and pressure wash (A), pressurized steam followed by forced hot air (B), or no cleaning (C). Drawers were classified as top, middle, or bottom based on their relative position with each other. After treatment, broilers were introduced to each drawer and held for 2, 4, or 6 h. At each timepoint, broilers were removed from drawers, euthanized, and carcasses rinsed to obtain Salmonella counts. Samples under the limit of direct plating detection were enriched, plated, and later confirmed positive or negative. Differences were observed per treatment, holding time, and drawer relative position (P < 0.0001). Broilers placed in transport containers that underwent a cleaning procedure (A or B) had lower levels of Salmonella when compared to broilers placed in noncleaned containers (C). However, most of the samples below the limit of detection were positive after enrichment, indicating that both procedures evaluated need improvement for efficient pathogen inactivation. A decrease in Salmonella transfer was observed after 6 h in rinsates obtained from broilers placed in noncleaned containers (C). Rinsates obtained from top drawers had less Salmonella than the middle or bottom drawers when broilers were placed in transport containers that underwent a cleaning procedure (A and B). The application of pressurized steam and forced hot air was comparable to the use of water washes and disinfectant indicating a potential role in cleaning poultry transport containers.

Application of pressurized steam and forced hot air for cleaning broiler transport container flooring.

In the United States, cleaning poultry transport containers prior to arrival at the broiler grow-out farm is not currently a widely adopted practice in the industry. However, previous studies have shown that transport containers have an important role in cross-contamination before the broilers arrive at the processing plant. The objective of this study was to evaluate the efficacy of pressurized steam followed by forced hot air to clean transport container flooring and compare it to conventional cleaning procedures. Fiberglass and plastic flooring were cut into even pieces and inoculated with chicken intestinal contents containing Salmonella Infantis or Campylobacter jejuni. The cleaning treatments were pressurized steam, forced hot air, pressurized steam followed by forced hot air, water pressure washing, water pressure washing before and after disinfectant, and no cleaning. Counts for Salmonella, Campylobacter, Escherichia coli, coliforms, and aerobic bacteria were assessed. All reductions were made in comparison to noncleaned samples. Forced hot air applied by itself was not efficient in reducing Campylobacter, coliforms, and E. coli; and limited reductions (less than 1 log10 CFU/cm2) were observed for Salmonella and aerobic bacteria. Then, for all bacteria types evaluated, pressurized steam by itself showed reductions of 2.4 to 3.5 log10 CFU/cm2. Samples that were cleaned with a single-pressure water wash showed reductions of 4.0 to 4.6 log10 CFU/cm2 for all bacteria types. For Salmonella, Campylobacter, and E. coli, the greatest reductions were observed when samples were cleaned with pressurized steam followed by forced hot air (4.3-6.1 log10 CFU/cm2) or water washed before and after disinfectant (4.5-6.2 log10 CFU/cm2), and these treatments did not differ from each other. Pressurized steam followed by forced hot air was shown to be an efficient cleaning procedure to reduce poultry-associated pathogens on transport cage flooring, with the benefit of using less water than conventional water cleaning. Processors may be able to adapt this process to reduce potential cross-contamination and lessen the level of pathogens entering the processing plant.

Research Note: Bacterial composition of settled dust during growout of broiler chickens.

Dust present in poultry houses can disseminate bacteria in air and deposit them on surfaces. This study evaluated bacteria in settled dust during growout of broilers from 2 flocks (Flocks A and B). Dust samples for bacteria analyses were obtained during 6 wk of growout (Flocks A and B) and 1 wk after flock termination (Flock B) by environmental swabbing and collecting dust in petri dishes from multiple locations inside the poultry house. For weekly swabbing, dust deposited during each wk of the sampling period (noncumulatively, n = 12/wk) and cumulatively (n = 12/wk) throughout the sampling period was collected. Swabbed dust samples were analyzed for counts (log10 CFU/28 cm2) of aerobic bacteria, E. coli, coliforms, and Salmonella recovery. For petri dish dust collection, dust was collected in weekly and bi-weekly time spans during the sampling period and then analyzed for Salmonella recovery. Data were analyzed by one-way ANOVA and Fisher's Exact Test and means were separated using LSD. Only aerobic plate counts changed over time in dust during growout (Flocks A and B; P < 0.0001). In noncumulatively settled dust, aerobic bacteria (Flocks A and B; P < 0.0001), E. coli (Flock A; P = 0.0432), and coliforms (Flock B; P = 0.0303) varied during growout with peak counts on wk 5 or wk 6, wk 4, and wk 4, respectively, after bird placement. Salmonella recovery did not vary in cumulatively (3/72, 10/84) and noncumulatively (0/12, 10/84) settled dust during growout in both flocks. In dust sampled by bi-weekly collection in petri dishes, Salmonella recovery was highest (5/6) between wk 2 to wk 4 for Flock B (P = 0.0118). Overall, this study displayed that settled dust bacteria levels can fluctuate during broiler growout, and dust can contain Salmonella.

Investigation of the potential of aerosolized Salmonella Enteritidis on colonization and persistence in broilers from day 3 to 21.

The presence of Salmonella in air of poultry houses has been previously confirmed. Therefore, it is important to investigate the entry of Salmonella into broilers through air. The present study aimed to evaluate different levels of Salmonella Enteritidis aerosol inoculations in broiler chicks for colonization of ceca, trachea, and liver/spleen and persistence over time. In 3 independent trials, 112 one-day-old birds were randomly divided into 4 groups (n = 28/group). On d 1 of age, one group was exposed to an aerosol of sterile saline and the remaining three groups were exposed to an aerosol generated from one of 3 doses (103, 106, or 109 CFU/mL) of S. Enteritidis inoculum. Aerosol exposure time was 30 min/group and was performed using a nebulizer. On d 3, 7, 14, and 21 of age, ceca, trachea, and liver/spleen were aseptically removed. Ceca were cultured for Salmonella counts (log10 CFU/g) and all tissues were cultured for Salmonella prevalence. All tissues from the control group were Salmonella negative for all sampling days. On sampling d 3 and 7, ceca Salmonella counts were highest (5.14 and 5.11, respectively) when challenged with 109Salmonella (P ≤ 0.0281). Ceca Salmonella counts increased from d 3 (2.43) to d 7 (4.43), then remained constant when challenged at 103Salmonella, and counts decreased over time for all other groups. Tissue Salmonella prevalence increased with increasing challenge levels at all sampling timepoints (P ≤ 0.0213). Salmonella prevalence was low (0/18 to 4/18) and did not change over time following 103Salmonella challenge (P ≥ 0.2394). Prevalence decreased over time in ceca and trachea following 106 and 109Salmonella challenge (P ≤ 0.0483). Liver/spleen Salmonella prevalence increased from d 3 (13/18) to d 14 (18/18) and then decreased at d 21 (10/18) in birds exposed to an aerosol of 109Salmonella but remained constant over time for rest of the Salmonella inoculated groups. Overall, this study demonstrated the Salmonella colonization and persistence in different tissues in broilers following exposure to aerosolized Salmonella.

Impact of poultry litter Salmonella levels and moisture on transfer of Salmonella through associated in vitro generated dust.

Dust present in poultry houses can contain high concentrations of microorganisms and has the potential to include pathogens from the litter. The objective of this study was to examine in vitro the potential for litter to dust transfer of aerobic bacteria, Salmonella, E. coli, and coliforms, and the role of the litter moisture on this process. Poultry litter was inoculated with 102 to 109 CFU/mL of Salmonella Typhimurium to evaluate litter to dust transfer of bacteria (Experiment 1). To evaluate the effect of litter moisture on litter to dust microbial transfer (Experiment 2), litter was inoculated with 109S. Typhimurium with increasing amounts of sterilized water added for moisture adjustment. Dust was generated by blowing air in a direct stream onto inoculated litter while simultaneously collecting dust through impingement. Following litter and dust sample collection, microbial analyses for aerobic plate counts (APC),Salmonella, E. coli, and coliforms were conducted. Both experiments were repeated 5 times and their data analyzed by one-way ANOVA and simple logistic regression. In Experiment 1, APC of litter (log10 CFU/g) and dust samples (log10 CFU/L) were 10.55 and 4.92, respectively. Salmonella ranged from 1.70 to 6.16 log10 CFU/g in litter and only one dust sample had 1.10 log10 CFU/L of Salmonella. As Salmonella levels in litter increased, the probability of obtaining a dust Salmonella positive result also increased. In Experiment 2, attained moisture percentages were 13.0, 18.2, 23.0, 28.2, and 33.3%. Litter recovery for APC, Salmonella, E. coli, and coliforms counts did not differ (P > 0.05) with increasing moisture levels. Dust sample bacterial counts significantly decreased with increasing moisture levels (P < 0.0001). Results from this in vitro study indicate that there is potential for Salmonella to be present in generated dust and the higher levels of Salmonella in litter increase the likelihood of detecting Salmonella in dust. Additionally, with higher litter moisture percentage, prevalence of Salmonella in generated dust was decreased.

Antimicrobial susceptibility patterns of clinical Escherichia coli isolates from dogs and cats in the United States: January 2008 through January 2013.

Escherichia coli is among the most common bacterial pathogens in dogs and cats. The lack of a national monitoring program limits evidence-based empirical antimicrobial choices in the United States. This study describes antimicrobial susceptibility patterns for presumed clinical E. coli isolates from dogs (n=2392) or cats (n=780) collected from six geographic regions in the United States between May 2008 and January 2013. Minimum inhibitory concentrations (MIC) were determined for 17 drugs representing 6 drug classes. Urinary tract isolates were most common (71%). Population MIC distributions were generally bimodal with the second mode above the resistant breakpoint for all drugs except gentamicin, amikacin, and meropenem. The MIC90 exceeded the susceptible breakpoint for ampicillin, amoxicillin-clavulanic acid, cephalothin (surrogate drug for cephalexin), and doxycycline but was below the susceptible breakpoint for all others. None of isolates was susceptible or resistant to all drug tested; 46% were resistant to 1 or 2 antimicrobial categories, and 52% to more than three categories. The resistance percentages were as follows: doxycycline (100%), cephalothin (98%)>ampicillin (48%)>amoxicillin-clavulanic acid (40%)>ticarcillin-clavulanic acid (18%)>cefpodoxime (13%), cefotaxime (12%), cefoxitin (11%), cefazolin (11%), enrofloxacin (10%), chloramphenicol (9.6%)>ciprofloxacin (9.2%), ceftazidime (8.7%), trimethoprim-sulfamethoxazole (7.9%), gentamicin (7.9%)>meropenem (1.5%), amikacin (0.7%) (P<0.05). Resistance to ampicillin and amoxicillin-clavulanic acid was greatest in the South-Central region (P<0.05). E. coli resistance may preclude empirical treatment with doxycycline, cephalexin, ampicillin, or amoxicillin-clavulanic acid. Based on susceptibility patterns, trimethoprim-sulfonamides may be the preferred empirical oral treatment.

Acid resistance systems required for survival of Escherichia coli O157:H7 in the bovine gastrointestinal tract and in apple cider are different.

Escherichia coli O157:H7 is a highly acid-resistant food-borne pathogen that survives in the bovine and human gastrointestinal tracts and in acidic foods such as apple cider. This property is thought to contribute to the low infectious dose of the organism. Three acid resistance (AR) systems are expressed in stationary-phase cells. AR system 1 is sigma(S) dependent, while AR systems 2 and 3 are glutamate and arginine dependent, respectively. In this study, we sought to determine which AR systems are important for survival in acidic foods and which are required for survival in the bovine intestinal tract. Wild-type and mutant E. coli O157:H7 strains deficient in AR system 1, 2, or 3 were challenged with apple cider and inoculated into calves. Wild-type cells, adapted at pH 5.5 in the absence of glucose (AR system 1 induced), survived well in apple cider. Conversely, the mutant deficient in AR system 1, shown previously to survive poorly in calves, was susceptible to apple cider (pH 3.5), and this sensitivity was shown to be caused by low pH. Interestingly, the AR system 2-deficient mutant survived in apple cider at high levels, but its shedding from calves was significantly decreased compared to that of wild-type cells. AR system 3-deficient cells survived well in both apple cider and calves. Taken together, these results indicate that E. coli O157:H7 utilizes different acid resistance systems based on the type of acidic environment encountered.