The present survey was undertaken to determine the mycoflora of broiler houses. Attempts were made to isolate and identify fungi in the dust, feed, litter and water from 21 broiler houses. A total of 166 isolates of fungi was identified as yeast spp. (44%), Aspergillus spp. (30.7%), Verticillium spp. (7.2%), Penicillium spp. (3.6%), Paecilomyces spp. (3.6%), Scopulariopsis spp. (3.0%), Cephalosporium spp. (3.0%), Chrysosporium spp. (2.4%), Cladosporium spp. (1.8%) and Absidia spp. (0.6%).

To determine whether an anti-Salmonella bacterium is involved in control of pathogen load in persistently infected cattle herds. 24 Holstein calves experimentally infected and 39 Holstein cows naturally infected with Salmonella spp. An Escherichia coli (designated as P8E5) that possessed anti-Salmonella activity was isolated from Salmonella-negative bovine feces obtained from a herd with endemic Salmonella infection. In vitro analysis involved enumerating Salmonella enterica serovar Typhimurium coincubated with E coli P8E5. In vivo analysis involved coadministration of Salmonella spp and E coli P8E5 or an E coli control strain to neonatal Holstein calves. Fecal samples were collected on multiple days after inoculation, and quantitative PCR assay was performed by use of Salmonella-specific primers. E coli P8E5 reduced viability of Salmonella spp in vitro. Shedding of Salmonella organisms was diminished in calves administered E coli P8E5, whereas the control strain of E coli had no effect on shedding of Salmonella organisms. In this study, an E coli strain was identified that possessed bacteriocin-like activity and was able to decrease viability of Salmonella organisms in vitro and in vivo. Therefore, it is possible that this organism could be representative of native microbiota that dampen Salmonella spp in persistently infected cattle herds.

Objective-To measure effects of Escherichia coli O149:F4-induced diarrhea on water consumption and pharmacokinetics of amoxicillin after administration in drinking water. Animals-24 recently weaned 24- to 28-day-old crossbred pigs. Procedure-10 pigs were inoculated with E coli O149:F4; all 10 pigs subsequently developed diarrhea. Pigs were medicated by administration of amoxicillin in the drinking water (0.75 mg/mL) for a 4-hour period on 2 consecutive days. Fourteen age-matched noninfected healthy pigs (control group) were medicated in a similar manner. Blood samples were obtained from both groups daily, and plasma concentrations of amoxicillin were analyzed by use of high-performance liquid chromatography. Results-Diarrhea reduced the area under the plasma concentration-versus-time curve (AUC) and maximum plasma concentration (C(max)) of amoxicillin on the first day of medication by 56% and 63%, respectively. The AUC of amoxicillin on the second day of medication for diarrheic pigs did not differ significantly from that of control pigs on the first day of medication. Conclusions and Clinical Relevance-E coli-induced diarrhea reduced the AUC of amoxicillin and time that plasma concentration of amoxicillin was > 0.025 microgram/mL and, hence, less likely to have a therapeutic effect on the first day of administration in drinking water. On the assumption that plasma concentrations may indirectly reflect concentrations at the site of infection, analysis of our results suggests that higher doses of amoxicillin may be appropriate for administration in drinking water during a 4-hour period on the first day that pigs have diarrhea attributable to E coli O149:F4.

Objective-To determine the susceptibility of strains of Pasteurella multocida subsp multocida isolated from lung specimens of pigs with pneumonia to 20 antimicrobials and to evaluate the emergence of resistance to those antimicrobials in Spain during the past 2 decades. Sample Population-63 isolates recovered from 1987 to 1988 and 132 isolates recovered from 2003 to 2004. Procedure-A broth microdilution method was used to determine minimal inhibitory concentration (MIC) range and values for MIC50 and MIC90. Resistance of a strain to an antimicrobial agent was determined by use of the breakpoint value when available. Results-Isolates were generally susceptible to penicillin, ampicillin, ceftiofur, gentamicin, apramycin, neomycin, spectinomycin, chlortetracycline, erythromycin, tilmicosin, enrofloxacin, and florfenicol, and most isolates were resistant to clindamycin, tylosin tartrate, and tiamulin regardless of the time period. A substantial increase in resistance to sulfachlorpiridazine, sulfadimethoxine, sulfathiazole, and trimethoprim-sulfamethoxazole was observed, and a minor increase in resistance to oxytetracycline was also detected. Several multiresistance patterns were observed, most frequently among isolates recovered in the 2003 to 2004 interval. Conclusions and Clinical Relevance-Ceftiofur, florfenicol, and enrofloxacin are recommended for treatment of infections caused by P multocida subsp multocida in Spain. Increased frequency of resistance to oxytetracycline and sulfonamide drugs may be a contraindication for their use.

Objective-To describe the prevalence of antibodies against Salmonella spp in swine marketed in Iowa. Animals-Swine marketed by 1,044 low-volume producers and 45 high-volume producers. Procedure-Samples of diaphragm muscle collected from swine carcasses were tested by an indirect ELISA based on lipopolysaccharides from Salmonella spp, in particular Salmonella serovar Typhimurium. Prevalence of positive results for antibodies against Salmonella spp for carcasses, lots, and swine for each producer was determined. Producer-level seroprevalence was used to classify swine from producers as having negligible, low, moderate, or widespread evidence of previous or historical exposure to Salmonella spp. Results-From low-volume producers, 23,609 of 25,478 (92.7%; 95% confidence interval CI, 92.4% to 92.9%) samples had negative results, and 1,863 (7.3%; 95% CI, 7.05% to 7.56%) had antibodies against Salmonella spp. Of the 6,299 lots of swine tested, 1,191 (18.9%) contained at least 1 sample with positive results. From high-volume producers, 203 of 2,486 (8.1 %; 95% CI, 6.8% to 9.3%) samples had antibodies against Salmonella spp, and 124 of 629 lots had at least 1 sample with positive results for antibodies against Salmonella spp. Conclusions and Clinical Relevance-Less than 10% of pigs marketed in Iowa are apparently exposed to Salmonella spp. Most swine marketed by low-volume producers had negligible or little evidence of exposure to Salmonella spp, whereas a higher percentage of swine marketed by high-volume producers had positive results when tested to detect antibodies against Salmonella spp.

Archival specimens of gastric mucosa of 10 raccoons (Procyon lotor), 9 porcupines (Erethizon dorsatum), 6 grey foxes (Urocyon cinereoargenteus), 6 bobcats (Lynx rufus), 4 skunks (Mephitis mephitis), and 3 black bears (Ursus americanus) were microscopically examined for evidence of Helicobacter-like organisms. Such organisms were seen in the specimens from the grey foxes and bobcats only. Histochemical stains (modified Steiner and carbol fuchsin methods) revealed long spiral organisms within lumina of gastric glands; however, neither gross nor microscopic lesions were observed. By electron microscopy (EM), the organisms were found to be free in the glandular lumina and were seen occasionally in the cytoplasm of gastric epithelial cells. Morphologically, 2 different phenotypes of spiral organisms were identified by EM. The organisms associated with bobcats appeared to be more tightly coiled than those seen in grey foxes. The presence of Helicobacter-like organisms in the gastric mucosa of grey foxes has not previously been described.

Objective - To evaluate the effectiveness of various sampling techniques for determining antimicrobial resistance patterns in Escherichia coli isolated from feces of feedlot cattle. Sample Population - Fecal samples obtained from 328 beef steers and 6 feedlot pens in which the cattle resided. Procedure - Single fecal samples were collected from the rectum of each steer and from floors of pens in which the cattle resided. Fecal material from each single sample was combined into pools containing 5 and 10 samples. Five isolates of Escherichia coli from each single sample and each pooled sample were tested for susceptibility to 17 antimicrobials. Results - Patterns of antimicrobial resistance for fecal samples obtained from the rectum of cattle did not differ from fecal samples obtained from pen floors. Resistance patterns from pooled samples differed from patterns observed for single fecal samples. Little pen-to-pen variation in resistance prevalence was observed. Clustering of resistance phenotypes within samples was detected. Conclusions and Clinical Relevance - Studies of antimicrobial resistance in feedlot cattle can rely on fecal samples obtained from pen floors, thus avoiding the cost and effort of obtaining fecal samples from the rectum of cattle. Pooled fecal samples yielded resistance patterns that were consistent with those of single fecal samples when the prevalence of resistance to an antimicrobial was > 2%. Pooling may be a practical alternative when investigating patterns of resistance that are not rare. Apparent clustering of resistance phenotypes within samples argues for examining fewer isolates per fecal sample and more fecal samples per pen.

Reduced prevalence of diarrhea and mortality has been reported after dietary supplementation with zinc compounds in swine with naturally acquired colibacillosis and those challenge-exposed with Serpulina hyodysenteriae; however, the usefulness of this approach for control of enteric diseases of swine remains to be determined. To examine the effect of dietary zinc-containing compounds on the colonization and development of cecal lesions associated with S hyodysenteriae infection, a defined diet alone or with added ZnO, ZnSO4, or Zn-methionine complex to a final concentration of approximately 6,000 mg of Zn2+/kg of complete feed was fed ad libitum to 156 female mice (strain C3H/HeN) for 10 days prior to oral inoculation either with S hyodysenteriae or sterile trypticase soy broth. Rations were continued for 42 days, while at weekly intervals, 3 mice/group were necropsied for determination of body weight, cecal weight, liver zinc concentration, presence of S hyodysenteriae in the cecum, and gross and histologic assessments of cecal lesions. From postinoculation day 0 to 42, the liver zinc concentration of mice fed the zinc-supplemented diets was approximately twice that of mice fed the basal diet, irrespective of the source of zinc. From postinoculation day 7 through 42, the overall recovery rate of S hyodysenteriae in infected mice fed the basal diet was 77.8%. In contrast, recovery rates of S hyodysenteriae from S hyodysenteriae-inoculated mice fed the zinc-supplemented diets were 0% for Zn-methionine and ZnO and 16.7% for ZnSO4. Mice fed the basal diet had significantly (P < 0.05) higher weight gain than mice fed the zinc-supplemented diets. However, the severity of cecal lesions, as determined by histologic examination and quantitative determination of longitudinal crypt length of the cecum was significantly (P < 0.05) less in mice fed the zinc-supplemented diets than in mice fed the basal diet. Data from this study indicate that dietary supplementation with 6,000 mg of zinc/kg of feed significantly reduced the recovery rate of S hyodysenteriae and provided partial protection against development of cecal lesions in mice inoculated with S hyodysenteriae. However, at this concentration, zinc had a deleterious effect on growth of the mice.

Aflatoxin (AF)-contaminated and fumonisin B1 (FB1)-contaminated (culture material from Fusarium moniliforme) diets were fed singly and in combination to growing cross-bred barrows. Six barrows (3 replicates of 2 each; mean body weight, 17.5 kg) per group were fed: 0 mg of AF and 0 mg of FB1/kg of feed (control); 2.5 mg of AF/kg of feed; 100 mg of FB1/kg of feed; or 2.5 mg of AF plus 100 mg of FB1/kg of feed for 35 days. The effects on production performance, serum biochemical, hematologic, immunologic, and pathologic measurements were evaluated. Body weight, gain, and feed consumption were significantly (P < 0.05) decreased by AF and AF plus FB1 diets. The FB1 diet decreased feed consumption, and although body weight was numerically decreased, it was not statistically significant. Aflatoxin increased serum gamma-glutamyltransferase (GGT) activity and total iron concentration and decreased urea nitrogen concentration and unsaturated iron-binding capacity. The FB1-alone diet increased serum GGT activity, whereas the AF plus FB1 diet increased serum aspartate transaminase, cholinesterase, alkaline phosphatase, and GGT activities, increased RBC count, triglycerides, and total iron concentrations, and decreased unsaturated iron-binding capacity and urea nitrogen concentration. For the most part, the effects of the AF plus FB1 diet on body weight and hematologic measurements could be considered additive. However, the effect of the AF plus FB1 diet on cholinesterase and alkaline phosphatase activities was greater than additive and was a synergistic response. One pig in the FB1-diet group and 2 pigs in the combination-diet group died. Postmortem lesions in pigs of the FB1-diet group consisted of ascites and increased liver weight. Observations at necropsy for pigs of the AF plus FB1-diet group consisted of hydrothorax, ascites, pulmonary edema, gastric erosions and ulceration, and increased liver and spleen weights. The AF diet increased relative liver weight and resulted in liver that was pale, rubbery, and resistant to cutting. Histologic lesions consisted of hepatic necrosis or degeneration, or both, with variable degrees of bile duct proliferation in barrows of the AF-diet groups. Renal tubular nephrosis was observed in barrows of the FB1 diet group, but this was not consistent in the AF plus FB1-diet group. Cell-mediated immunity, as measured by mitogen-induced lymphoblastogenic stimulation index, was decreased in barrows of the AF and FB1-diet groups, and values in barrows given the combination diet were significantly decreased from those in barrows given the single toxin diets. It was concluded that AF and FB1 (from culture material), singly or in combination, can adversely affect clinical performance, serum biochemical, hematologic, and immunologic values and induce lesions in growing barrows. For most of the variables we evaluated under our study conditions and dosages of toxins, measurements were affected more by the combination diet than by either single toxin diet, and the toxic responses could be described as additive or more than additive, particularly for induction of liver disease.

Eight Holstein cows, 4 inoculated intracisternally in 1 quarter of the mammary gland with Escherichia coli and 4 noninfected controls, were administered ceftiofur sodium (3 mg/kg of body weight, IV, q 12 hours) for 24 hours, beginning at 14 hours after inoculation of infected cows. All challenge-exposed cows became infected, with mean +/- SEM peak log10 bacterial concentration in milk of 5.03 +/- 0.69 colony-forming units/ml. The infection resulted in systemic signs (mean peak rectal temperature, 41.5 +/- 0.3 C; anorexia; signs of depression) and local inflammation (mean peak albumin concentration in milk, 7.89 +/- 1.71 mg/ml). Ceftiofur was detectable in milk from all challenge-exposed cows, compared with only 1 of 4 noninfected cows, and the mean period after inoculation that ceftiofur was detectable in milk was longer (P < 0.05) in infected (147.7 +/- 27.5 hours) than noninfected cows (1.3 +/- 1.3 hours). However, maximal ceftiofur concentration attained in milk for all cows was 0.28 micrograms/ml, and was 0.20 micrograms/ml or less for all but 2 milk samples collected for 10 days after challenge exposure. Mean serum concentration of ceftiofur peaked at 1.0 +/- 0.3 micrograms/ml and 0.7 +/- 0.1 micrograms/ml for infected and noninfected COWS, respectively. After each ceftiofur dose, mean peak and trough concentrations of ceftiofur in serum did not differ between groups; however, concentration of ceftiofur in serum was higher at 7 hours after each dose in noninfected cows, suggesting more rapid clearance of the drug in infected cows. Ceftiofur was not detected in serum (< 0.05 micrograms/ml) of any cow at or after 120 hours following inoculation of infected cows. Storage of serum samples at -20 C for 3 weeks resulted in a 98.8% decrease in ceftiofur activity, compared with that in fresh serum samples. Eighty-seven percent of this loss occurred 30 minutes after mixing serum and ceftiofur; thus, about 13% of the original activity was lost in storage. Storage of milk samples under similar conditions did not result in loss of ceftiofur activity. Despite acute inflammation, the dosage of ceftiofur used in this trial would not result in drug concentrations in milk above FDA safe concentrations, or above the reported minimum inhibitory concentration for coliform bacteria.