Screening of Salmonella isolates from a turkey production facility for antibiotic resistance

High-resolution Serotyping Reveals Salmonella Surveillance Challenges in the Turkey Industry

Despite extensive Salmonella controls used at processing, 5.5% of salmonellosis cases are linked to turkey. This study had two objectives: (i) to summarize USDA-FSIS turkey Salmonella verification program data and (ii) to evaluate Salmonella through turkey production and processing of 22 flocks. In objective 1, USDA-FSIS data show the average Salmonella prevalence in ground turkey from 2016 to 2022 was 15.9%, and that the leading serovar changes frequently. For objective 2, bootsocks (n = 22) were collected on-farm right after load-out. At processing, prescald wingtips (n = 6 composites of 10/flock), prechill wingtips (n = 6 composites of 10/flock), mechanically separated turkey (MST; n = 6 bins/flock), and ground turkey (n = 6 bins/flock) were collected. Salmonella prevalence was determined by a commercial qPCR and culture confirmed. In 33.2% of PCR-positive samples, Salmonella was not confirmed by culture, highlighting a discrepancy between molecular and culture detection. On-farm, 8/22 flocks were Salmonella positive, compared to 21 flocks that were positive at one or more processing locations, including 18 flocks that were positive in at least one final product sample. A logistic regression showed higher Salmonella prevalence in prescald (53.8%) than in prechill (18.2%), MST (27.3%) or ground turkey (26.5%). CRISPR-SeroSeq analysis of 148 culture-positive samples detected 18 Salmonella serovars and showed 35.1% of samples contained multiple serovars. In 16 flocks, one or more serovars detected in final products were absent from any upstream samples. Two-thirds of final product samples containing serovar Typhimurium typed as a live-attenuated Typhimurium vaccine strain. Salmonella on-farm and at prescald did not reflect Salmonella observed in final product. These data underscore the complexity of serovar tracking in turkey production and highlight challenges to identify surveillance samples that accurately represent Salmonella in turkey products.

Prevalence, Molecular Detection, and Antimicrobial Resistance of Salmonella Isolates from Poultry Farms across Central Ethiopia: A Cross-Sectional Study in Urban and Peri-Urban Areas

A cross-sectional study was conducted to assess the prevalence, molecular detection, and antimicrobial resistance of Salmonella isolates within 162 poultry farms in selected urban and peri-urban areas of central Ethiopia. A total of 1515 samples, including cloacal swabs (n = 763), fresh fecal droppings (n = 188), litter (n = 188), feed (n = 188), and water (n = 188), were bacteriologically tested. The molecular detection of some culture-positive isolates was performed via polymerase chain reaction (PCR) by targeting spy and sdfl genes for Salmonella Typhimurium and Salmonella Enteritidis, respectively. Risk factors for the occurrence of the bacterial isolates were assessed. Antimicrobial susceptibility testing of PCR-confirmed Salmonella isolates was conducted using 12 antibiotics. In this study, it was observed that 50.6% of the farms were positive for Salmonella. The overall sample-level prevalence of Salmonella was 14.4%. Among the analyzed risk factors, the type of production, breed, and sample type demonstrated a statistically significant association (p < 0.05) with the bacteriological prevalence of Salmonella. The PCR test disclosed that 45.5% (15/33) and 23.3% (10/43) of the isolates were positive for genes of Salmonella Typhimurium and Salmonella Enteritidis, respectively. The antimicrobial susceptibility test disclosed multi-drug resistance to ten of the tested antibiotics that belong to different classes. Substantial isolation of Salmonella Typhimurium and Salmonella Enteritidis in poultry and on poultry farms, along with the existence of multi-drug resistant isolates, poses an alarming risk of zoonotic and food safety issues. Hence, routine flock testing, farm surveillance, biosecurity intervention, stringent antimicrobial use regulations, and policy support for the sector are highly needed.

Effects of Clostridium butyricum on Growth Performance, Gut Microbiota and Intestinal Barrier Function of Broilers

This study was conducted to evaluate the effects of Clostridium butyricum dietary supplementation on the growth, antioxidant, immune response, gut microbiota, and intestinal barrier function of broilers under high stocking density (HSD) stress. A total of 324 1-day-old Arbor Acres male broilers were randomly assigned to three treatments with six replicates, each replicate including 18 chickens (18 birds/m²). The experiment lasted 6 weeks. The three treatments were basal diet (control, CON), basal diet supplemented with 1 × 10⁹ colony forming units (cfu)/kg C. butyricum (CB), and basal diet supplemented with 10 mg/kg virginiamycin (antibiotic, ANT). The results showed that the body weight (BW) and average daily gain (ADG) of broilers in the CB group were significantly higher than those in the CON group in three periods (p < 0.05). The total antioxidant capacity (T-AOC) and the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity in serum of the CB group were significantly increased compared with those in the CON and ANT groups at 42 days (p < 0.05). At 42 days, the serum immunoglobulin M (IgM) and immunoglobulin G (IgG) levels of the CB group were significantly higher than those of the CON group. Compared with the CON group, interleukin-1β (IL-1β) in the CB group was significantly decreased in the starter and grower stages (p < 0.05), but there was no significant difference between the two treatment groups (p > 0.05). C. butyricum significantly decreased the high stocking density-induced expression levels of IL-1β and tumor necrosis factor-α (TNF-α) in the ileum of broilers at different stages. Additionally, C. butyricum could increase the expressions of claudin-1 and zonula occludens-1 (ZO-1) in intestinal tissue. Moreover, C. butyricum significantly increased the Sobs and Shannon indices in the CB group compared with the ANT group (p < 0.05), while the Ace index in the CB group was significantly higher than that of the CON group (p < 0.05). Furthermore, by using 16S rRNA gene sequencing, the proportion of Bacteroides in the CB group was increased compared to those in the CON and ANT groups at the genus level. In conclusion, C. butyricum supplemented into feed could improve the growth performance and feed utilization of broilers by promoting immune and intestinal barrier function and benefiting the cecal microflora.

Effects of dietary supplementation with Clostridium butyricum on laying performance, egg quality, serum parameters, and cecal microflora of laying hens in the late phase of production

This experiment was conducted to evaluate the effects of dietary supplementation with Clostridium butyricum on laying performance, egg quality, serum parameters, and cecal microflora of laying hens in the late phase of production. Jinghong-1 strain laying hens (n = 960; 48 wk of age) were randomly allocated to 5 treatment groups with 6 replicates of 32 hens. Hens were fed with basal diet (control) and basal diet supplemented with 2.5 × 104 (CB1), 5 × 104 (CB2), 1 × 105 (CB3), and 2 × 105 (CB4) cfu/g C. butyricum for 10 wk. The results showed that egg production, egg mass, and eggshell strength increased quadratically as supplemental C. butyricum increased, and these responses were maximized in the CB2 group (P < 0.05). Compared with the control group, the addition of C. butyricum resulted in quadratic effects on serum total protein, uric acid, calcium, complement component C3 and catalase concentrations, and these responses were maximized or minimized in the CB2 group (P < 0.05). Linear and quadratic increases were observed in serum IgM, total superoxide dismutase, and glutathione peroxidase concentrations, and these responses were maximized in CB2 or CB3 group (P < 0.05). The addition of C. butyricum in the CB2 group resulted in linearly increasing levels of serum IgG concentration as compared with the control group (P < 0.05). Spleen index increased (P < 0.05) in the CB2 group. Hens fed with C. butyricum reduced (P > 0.05) the population of E. coli, while Bifidobacterium counts increased quadratically and maximized in the CB2 group (P < 0.05). In conclusion, the results indicated that dietary supplementation with C. butyricum (5 × 104 or 1 × 105 cfu/g) could improve laying performance and egg quality by promoting immune function, enhancing antioxidative capacity, and benefiting the cecal microflora of laying hens in the late phase of production.

Prevalence and antimicrobial resistance patterns of Salmonella isolated from poultry farms in southeastern United States

Salmonella spp. are among the most common foodborne pathogens, and increase in the occurrence of antimicrobial drug-resistant Salmonella poses a severe risk to public health. The main objective of this study was to determine changes in Salmonella prevalence and their antimicrobial resistance on poultry farms following recommendations to changes in biosecurity practices. Four poultry farms were sampled by collecting cloacal swabs, drag swabs, and litter samples prior to recommended biosecurity changes (March-April) and post recommendations (October-November). Prevalence of Salmonella was 3 to 4% during pre-recommendations, while the prevalence was higher (P > 0.05), ranging from 5 to 14% during post recommendations. Higher Salmonella prevalence was observed for pre- and post-recommendation phases by sample type in cloacal and drag samples -5% for farm 1, drag swab -6% on farm 2, cloacal swab -6% for farm 3, and drag swab -17% on farm 4. The PCR confirmed Salmonella were serotyped and tested for antimicrobial resistance. Six serotypes of Salmonella were identified with S. Enteritidis (52%) being the most prevalent, followed by S. Berta (38%), S. Mbandaka (7%), S. Typhimurium (2%), S. Kentucky (0.4%), and S. Tennessee (0.4%). A total of 7% isolates exhibited resistance to at least one of the 8 antimicrobials. Higher resistance was observed for tetracycline, streptomycin, and nalidixic acid. A single isolate of S. Mbandaka exhibited multidrug resistance to tetracycline, amoxicillin/clavulanic acid, and ampicillin. Based on these prevalence results, it can be inferred that, irrespective of implementation of improved biosecurity practices, seasonal variation can cause changes in the prevalence of Salmonella on the farms. Resistance to clinically important antimicrobials used to treat salmonellosis is a concern to public health.

Effects of a direct-fed microbial (primalac) on turkey poult performance and susceptibility to oral Salmonella challenge

A study was conducted to determine 1) the effect of a dietary direct-fed microbial (DFM) on turkey poult performance, 2) the effect of a DFM on a Salmonella challenge, and 3) the effect of feed processing on the efficacy of the dietary DFM. Day-of-hatch Large White female poults were placed in 2 rooms in 2 Petersime batteries per room. Twelve pens of 7 birds each were used in each battery (24 pens per room, 336 birds total). One of 4 dietary feed treatments was assigned to each pen (6 pens per room for each diet). One room housed non-Salmonella-challenged poults, and the other room housed poults challenged with a 1-mL oral gavage of Salmonella (10(10) cfu/mL). A single batch of starter ration was split into 4 parts and used to provide 4 dietary treatments: 1) mash feed with no DFM (M), 2) mash feed with DFM (Primalac; 0.9 kg/tonne of feed, MD), 3) pelleted (20-s steam conditioning at 80 degrees C) and crumbled feed with no DFM (C), and 4) pelleted and crumbled feed with DFM (CD). Feed and deionized, distilled water were provided ad libitum. Data were collected and analyzed separately for each room. Mortality was recorded for each pen on a daily basis and totaled by week and for the 3-wk period. Individual BW and feed consumption, by pen, were measured weekly. Weekly and cumulative BW gains and feed to gain ratios (F:G) were calculated. Liver, spleen, total and lower intestinal tract weights, intestinal length, and most-probable-number Salmonella populations were determined for one randomly selected bird per pen. Feeding processed feed resulted in improved BW and F:G. Feeding the DFM improved 3-wk cumulative F:G in birds not gavaged and reduced relative intestinal weight in birds gavaged. Salmonella populations were reduced 1 log by feeding DFM. Dietary DFM improved bird performance, reduced Salmonella populations, and was not affected by feed processing.

Prevalence and antimicrobial resistance of Salmonella recovered from processed poultry

This study was conducted to determine the prevalence and antimicrobial resistance of Salmonella isolates recovered from processed poultry. Four hundred eighty pre- and postchill whole broiler chicken carcasses were collected from a poultry processing plant between July 2004 and June 2005. Water samples also were collected at the entrance and exit of the chiller. After preenrichment, carcass and water samples were analyzed for the presence of Salmonella using the automated BAX system followed by traditional culture methods. The proportions of pre- and postchill carcasses that were positive for Salmonella were 88.4 and 84.1%, respectively. Ninety-two percent of water samples collected at the entrance of the chiller were positive for Salmonella, but all exit samples were negative. There was no significant difference in the prevalence of Salmonella between pre- and postchill carcasses (P > 0.05). Salmonella isolates recovered were serotyped and tested for susceptibility to antimicrobials. Thirteen serotypes were identified; the most common were Salmonella Kentucky (59.5%) and Salmonella Typhimurium (17.8%). Three hundred thirty-nine (79.8%) of the isolates were resistant to at least one antimicrobial, and 53.4% were resistant to three or more antimicrobials. Resistance was most often observed to tetracycline (73.4% of isolates), ampicillin (52.9%), amoxicillin-clavulanic acid (52%), ceftiofur (51.7%), streptomycin (35.2%), and sulfisoxazole (21.8%). These results indicate the high prevalence of Salmonella contamination in whole broiler carcasses, and a large number of these Salmonella isolates were resistant to commonly used antimicrobials.

Rapid phenotypic characterization of Vibrio isolates by pyrolysis metastable atom bombardment mass spectrometry

Pyrolysis mass spectrometry was investigated for rapid characterization of food-borne bacterial pathogens. Nine isolates of Vibrio parahaemolyticus and one isolate each of Vibrio fluvialis, Vibrio hollisae, and Vibrio vulnificus were analyzed. Pyrolysis mass spectra, generated via an alternative ionization method, metastable atom bombardment, were subject to principal component-discriminant analysis. The spectral patterns were used to distinguish Vibrio isolates differing in species, serotype and expression of the thermostable direct hemolysin gene. The patterns of similarity and dissimilarity amongst spectra in the Vibrio test set generally reflected those associated with species, serotype or hemolysin-producing genes, though the combined influence of these and other variables in the multi-dimensional data did not produce a simple clustering with respect to any one of these characteristics. These results suggested that with enough examples to model the most common combinations, the method should be able to characterize Vibrio isolates according to their phenotypic characteristics. Pyrolysis-mass spectrometry with metastable atom bombardment and pattern recognition appeared suitable for rapid infraspecific comparison of Vibrio isolates. This integrated analytical, pattern-recognition system should be examined further for potential utility in clinical and public health diagnostic contexts.

Genetic diversity and virulence gene determinants of antibiotic-resistant Salmonella isolated from preharvest turkey production sources

This study evaluated the molecular diversity of 29 Salmonella serotypes isolated from turkey ceca and the production environment. Isolates were resistant to bacitracin (100%), erythromycin (100%), novobiocin (100%), rifampin (100%), streptomycin (62%), gentamicin (52%), spectinomycin (48%), tetracycline (31%), sulfamethoxazole/trimethoprim (SXT) (3%) and tobramycin (3%). The minimum inhibitory concentration (MIC) values ranged from 32 to >/=1024 microg/ml. The pulsed-field gel electrophoresis (PFGE) and ribotyping patterns were identical within each of the serotypes Heidelberg, Worthington and Muenster. The plasmid profiles were identical within each of the Salmonella serotypes. Two different clones of Salmonella anatum were differentiated by PFGE typing but not by ribotyping. Heidelberg isolates from nine turkey ceca and three drinker samples had identical antibiotic resistance, PFGE, ribotype and plasmid patterns, suggesting that transmission of this particular clone may have occurred between the birds and the drinkers. Identical PFGE, ribotype and plasmid patterns were observed in one Salmonella worthington isolate from turkey ceca in one flock and two S. worthington isolates from feeder contents and drinkers from a subsequent flock, suggesting transmission of this pathogen between flocks. Individual and multiple polymerase chain reaction (PCR) analyses revealed the presence of the virulence genes invA, aceK and sopB and the absence of the h-1i gene in all isolates. A combination of genotypic and phenotypic markers can be useful in studying genetic variation among natural salmonellae populations in turkey production and delineating possible transmission pathways.