Enrichment for isolating Salmonella Choleraesuis and other Salmonella spp. from pigs

The growth of Salmonella Choleraesuis was examined in Rappaport Vassiliadis broth (RV) and Hajna-tetrathionate broth (HTT) at 37 and 42 degrees C. As the enrichment in RV at 37 degrees C was satisfactory for isolating S. Choleraesuis, we used this enrichment for isolation from the samples collected from 15 asymptomatic pigs reared on a S. Choleraesuis contaminated farm. S. Choleraesuis was frequently isolated from six pigs (40.0%) under field conditions. The isolation of other Salmonella serovars than S. Choleraesuis was attempted by using both RV enrichment at 37 degrees C and HTT enrichment at 42 degrees C. Salmonella organisms were isolated from 156 (44.8%) of 348 fecal samples and more frequently with HTT at 42 degrees C (43.4%) than with RV at 37 degrees C (20.9%). If other serovars in addition to S. Choleraesuis are to be surveyed, HTT enrichment should be used in combination with RV enrichment.     

POSSIBLE PATHWAYS OF CONTAMINATION OF MEAT AND BONE MEAL WITH SALMONELLA

Samples taken at various points along the processing line in 2 rendering plants showed that post-processing contamination occurs almost immediately after termination of the heat process in the percolator and surge bin. Further contamination occurs at each processing stage. In plant A 12.5% of the samples collected from material leaving the surge bin, 36% of the samples of product after it has passed the milling stage and 61% of samples collected from the stored product were found to be contaminated with salmonellas. In plant B the results were 15%, 40% and 69% respectively. Heavy contamination of product left overnight in percolators and surge bins, which are not cleaned routinely, was considered an important source of early post-processing contamination. The ecology was found to be similar at both plants despite the fact that in one plant the uncooked and cooked areas were separated completely, whilst this was not the case in the other plant. None of the air samples collected yielded salmonellas, while nearly all the insect samples collected in the rendering plants yielded salmonellas.     

Salmonella in captive crocodiles (Crocodylus johnstoni and C. porosus)

The prevalence of salmonellas in captive Crocodylus porosus and C. johnstoni was investigated at 2 Northern Territory crocodile farms. Similar proportions of each species at one farm (20.0 and 27.8% for C. porosus and C. johnstoni, respectively) carried salmonellas, but at the other farm there was a significant difference between the 2 species (81.0 and 5.0%, respectively). Procedures for the slaughter of crocodiles and processing of crocodile flesh for human consumption are outlined and discussed from the viewpoint of minimising salmonella contamination. The prevalence of salmonellas on flesh for human consumption (16.0% of carcases) was higher than that reported for beef and mutton, but lower than that for poultry products (Murrell 1986). Serotypes most often isolated from cloacai and faecal swabs were S. cerro, S. singapore, S. enteritidis and S. arizonae. Of the 10 serotypes isolated from processed carcases, S. singapore was most frequently isolated (33.3% of serotypes identified).     

The role of intestinal volatile fatty acids in the Salmonella shedding of pigs

Factors affecting colonization of the intestinal tract by salmonellas were studied in two pig herds. In herd H 18% of the faecal samples taken from live pigs and 30% of the colon content samples collected at slaughter contained salmonellas. In contrast, the 50 faecal samples taken from pigs of herd L were negative and only 2% of the colon contents collected at the yielded salmonellas. An antibacterial effect inhibiting salmonella multiplication was demonstrable in vitro in colon contents from pigs of herd L. No such effect was found to exist in samples taken from pigs of herd H. The antibacterial effect is due to the non-dissociated volatile fatty acid (VFA) molecules present in the colon content. As the degree of VFA dissociation depends on the pH of the environment, at lower pH values (pH 6.1 +/- 0.2) of the colon contents from herd L the ratio of non-dissociated VFA molecules is higher and the resulting antibacterial effect is stronger than in samples from herd H (pH 7.1 +/- 0.3).     

The occurrence of salmonella in waste water from Danish slaughterhouses. A quantitative study.

In waste water from 11 slaughterhouses, the occurrence of salmonellas were followed continually during a whole week. Thirty-eight samples out of 66 were contaminated. The mean concentrations of salmonellas varied between 0.9 and 668 per 100 ml. Only 4 different serotypes were found viz., S. agona, S. indiana, S. senftenberg, and S. typhimurium. This distribution of serotypes is incompatible with epidemiological data from humans, animals, and feed-stuffs. It is suggested that certain serotypes of Salmonella may become established in sewage systems of slaughterhouses or that propagation of salmonellas may take place in the sewer rats. In one particular plant, large numbers of S. senftenberg were found during the whole period of sampling. It is pointed out that discharge of such heavily polluted waste water into water courses may constitute a public health hazard if the recipient is used for irrigation of vegetables or pastures.     

EXAMINATION OF STOCKFEEDS FOR SALMONELLA

SUMMARY Of 100 stockfeeds examined for Salmonella 45 were positive by pre-enrichment followed by selective enrichment of 10 times 25 g samples. Forty-three were positive by selective enrichment of pooled aliquots of the pre-enrichment broths from the 10 times 25 g samples.
Aliquots of the pre-enrichment broths from the 10 times 25 g samples of 77 of the feeds were stored at 4°C and retested after 6 days. One hundred and ten of these (770) subsamples were found to contain salmonellas initially, and 107 were found to contain salmonellas after storage for 6 days.
The testing of feeds by the examination of multiple 25 g samples and pooled pre-enrichment broths is recommended. Aliquots of the pre-enrichment broths may be stored at 4°C for 6 days and retested if an estimation of the numbers in the feed is required. Further pre-enrichment after cold storage is not required.     

Sources of Salmonella contamination during broiler production in Eastern Spain

Prevention of Salmonella contamination of poultry products requires detailed knowledge of the main sources associated with its presence in the production system. The aims of this study were to determine the main sources of Salmonella contamination in broiler production during growing, to assess the risk factors for Salmonella contamination at the end of the rearing period and to determine the main serovars involved in broiler production systems in Eastern Spain. A total of 65 different broiler houses from different farms were sampled. Each house was sampled at different times during the rearing period. First, when the previous flock was taken to the slaughterhouse, samples of dust, surfaces and previous flock faeces were collected. After cleaning and disinfection (C&D), samples of dust and surfaces were also taken. On the first day of rearing, samples of water, bedding, farming boots, meconiums, delivery-box liners and feed were collected. During rearing, feed samples were taken directly from the truck and from feeders. On slaughter day, samples of dust, surfaces, water, feed and faeces were also collected. Finally, two days after slaughter, carriers (rodents, flies and beetles) were trapped. All samples collected were analysed according to ISO 6579:2002 (Annex D) and positive samples were serotyped in accordance with Kauffman-White-Le-Minor technique. Our results showed that all different types of samples collected were contaminated with Salmonella (prevalence ranged between 1.5% and 38.6%). The most contaminated samples related with poultry production were: delivery-box liners (32.0%), faeces samples (31.2%), dust samples (25.0%), farming boots (19.7%) and feed from feeders (16.0%). However, the most important risk factors for Salmonella contamination of the flocks at the end of the rearing period were Salmonella status of the house after cleaning and disinfection, Salmonella status of day-old chick flocks and feed from feeders. Twenty-one different serovars were isolated from the samples analysed. The most prevalent were in decreasing order: Salmonella Enteritidis (52.9%), S. Hadar (17.8%), S. Virchow (8.9%) and S. Ohio (5.4%). The study suggested that there are many sources for Salmonella contamination and persistence in broiler production. Hence, the whole production chain needs to be controlled to eradicate the bacteria from primary production.     

Antibacterial activity of milk-fermenting bacteria

Factors influencing salmonella survival in fermented milk products were investigated. Filtrates of yoghurt and cream cultures and a filtrate from milk precipitated by lactic acid were inoculated by salmonellas. The pH value was adjusted within the range of 7.0 to 4.5. The content of nondissociated lactic acid was determined. The filtrates were incubated 24 and 48 hours at a temperature of 37 degrees C. In comparison with the milk filtrate, great inhibitory (at pH 6.5) and bactericidal (at pH 5.5) effects of the yoghurt culture on salmonellas were proved. The filtrate from the cream culture inactivated salmonellas at pH 4.5, the growth ceased at pH 5.5. The effects of lactic and acetic acids on salmonellas at a concentration of 0.5% and pH 3.3, and acetic acid at a concentration of 0.05% and pH 5.1 were also studied.     

Incidence of Clostridium perfringens in broiler chickens and their environment during production and processing.

During a calendar year, a study was conducted involving 16 broiler flocks on four different farms, two farms belonging to each of two major U.S. poultry integrators. As determined by the detection of Clostridium perfringens in fecal or cecal samples, 15 (94%) of the flocks became positive for this bacterial enteropathogen, and only one remained negative throughout the 6-to-8-wk rearing period. Paper pads beneath chicks that were transported from the hatchery to the rearing house were contaminated with C. perfringens in 15 (94%) of the flocks. When sampled biweekly through grow out, 13 of the flocks were C. perfringens positive at 2 wk of age. These results suggest that colonization of the intestinal tract of broilers by C. perfringens is an early event. Of the environmental samples, all but feed in the hopper were contaminated before placement for at least one of the rearing periods. All sample types were contaminated at some point during the 6-to-8-wk grow-out period. Of the on-farm environmental samples, the highest incidences (percentage positive) of C. perfringens were detected in wall swabs (53%), fan swabs (46%), fly strips (43%), dirt outside the house entrance (43%), and swabs of workers' boots (29%). Birds were usually transported to the processing plant in coops that were already contaminated with C. perfringens. In the plant, C. perfringens was isolated more frequently from samples of scald water than from those of chill water. Clostridium perfringens was recovered from broiler carcasses after chilling in 13 (81%) of the 16 flocks. The proportion of C. perfringens-positive carcasses for the contaminated flocks ranged from 8% to 68% with a mean of 30%.     

The prevalence of Salmonella infections in camels (Camelus dromedarius) in the United Arab Emirates.

One hundred and eighty-seven salmonella strains were isolated from 4006 samples collected from camels in the United Arab Emirates between 1987 and 1991. One hundred and sixty-five (4.3%) strains were isolated from 3801 faecal and 22 from 205 organ samples of 62 autopsied camels. In total, 28 different serotypes were identified with S. saintpaul being the most frequent (69), followed by S. frintrop (31) and S. hindmarsh (15). Salmonella typhimurium was isolated from only two faecal specimens. All salmonellas isolated from faecal samples originated from carrier camels, and those isolated from organs were secondary findings. The camels from which salmonella organisms were found died from diseases other than salmonellosis. Most of the S. saintpaul isolates originated from one herd suffering from Clostridium perfringens type A enterotoxaemia which suggests that salmonella infections may predispose camels to clostridial enterotoxaemias.     

Control of salmonella infections in broiler chickens by the acid treatment of their feed

In three experiments a solution of formic acid (Bioadd) was added to feed 'naturally' contaminated with salmonellas. In two of them no salmonella infections were demonstrated in broiler chickens given feed containing 0.6 per cent (w/w) of the formic acid solution for seven weeks and in the third the infection rate was reduced considerably. In four other experiments the feed was contaminated artificially with between 1 and 47 Salmonella kedougou/g and a second product (BPO12), consisting of a mixture of formic acid and propionic acid, was evaluated. When it was added at 0.5 to 0.68 per cent (w/w) only one of 30 groups of 10 to 12 birds became infected with S kedougou by two weeks of age, compared with 22 of 27 control groups. The treatment of the feed with BPO12 one week before the addition of the salmonellas prevented the establishment of infection in chicks given the treated feed, indicating that acid treatment will provide protection against subsequent recontamination of the feed with the organisms. The isolation rate of S kedougou from artificially contaminated feed treated with BPO12 was reduced only slightly but the feed was apparently 'safe' for the birds which consumed it.     

Effects of blood contamination of cerebrospinal fluid on western blot analysis for detection of antibodies against Sarcocystis neurona and on albumin quotient and immunoglobulin G index in horses.

OBJECTIVE: To determine effects of blood contamination on western blot (WB) analysis of CSF samples for detection of anti-Sarcocystis neurona antibodies, and on CSF albumin and IgG concentrations, albumin quotient (AQ), and IgG index in horses. DESIGN: Prospective in vitro study. SAMPLES: Blood with various degrees of immunoreactivity against S neurona was collected from 12 healthy horses. Cerebrospinal fluid without immunoreactivity against S neurona was harvested from 4 recently euthanatized horses. PROCEDURE: Blood was serially diluted with pooled nonimmunoreactive CSF so that final dilutions corresponded to 10(-3) to 100 microliters of blood/ml CSF, and WB analysis was performed on contaminated CSF samples. Number of RBC, albumin and IgG concentrations, AQ, and IgG index were also determined. RESULTS: Antibodies against S neurona were detected in CSF contaminated with 10(-3) microliters of strongly immunoreactive blood/ml. In CSF samples contaminated with 10 microliters of blood/ml, AQ remained within reference range. Volume of blood required to increase IgG index varied among blood samples and was primarily influenced by serum IgG concentrations. Number of RBC in contaminated samples was correlated with volume of blood added, but not with degree of immunoreactivity detected in contaminated CSF samples. CONCLUSIONS AND CLINICAL RELEVANCE: During collection of CSF from horses, contamination with blood may introduce serum antibodies against S neurona at concentrations sufficient for detection by WB analysis, thus yielding false-positive results. When blood is moderately or strongly immunoreactive, the amount of contaminating albumin may be small enough as to not increase AQ above reference range. In these cases, AQ and IgG index should be interpreted with caution.     

Studies on flotation techniques for the recovery of helminth eggs from soil and the prevalence of eggs of Toxocara spp in some Kansas public places

A technique for extracting Toxocara spp eggs from soil had a recovery efficiency ranging from 53% to 68%. Using the technique, 50 of 232 (22%) soil samples from city and university properties were found to be contaminated with eggs of Toxocara spp. Of 50 samples from highway rest areas, 8 (16%) were contaminated. From a public health standpoint, it was particularly noteworthy that 9 of 23 (39%) samples from sandboxes in student family quarters were contaminated with Toxocara spp eggs.     

Molecular prevalence of Cryptosporidium spp. in dairy calves in Southern states of India

Dung samples were collected from dairy calves of south Indian states viz., Andhra Pradesh, Karnataka, Kerala, Tamil Nadu and union territory, Puducherry and are subjected to nested polymerase chain reaction (PCR) targeting 18S rRNA gene for detection of Cryptosporidium infection. Of the 459 dung samples screened 182 were found positive with a prevalence of 39.65%. Highest prevalence of Cryptosporidium was observed in Puducherry (86.67%) and lowest in Kerala (17.65%). Genotyping by PCR-restriction fragment length polymorphism (RFLP) and sequence analysis revealed the presence of all the four major Cryptosporidium species of cattle viz., Cryptosporidium andersoni, Cryptosporidium ryanae, Cryptosporidium parvum and Cryptosporidium bovis. C. andersoni was widely distributed in calves of Tamil Nadu, Karnataka and Puducherry whereas in Andhra Pradesh C. ryanae was the major species. Of the 64 samples subjected to PCR-RFLP, 39 (60.94%) could be classified as C. andersoni, 18 (28.13%) as C. ryanae, 4 (6.25%) as C. parvum and 3 (4.69%) were confirmed as C. bovis. The results were also confirmed by sequencing of 19 Cryptosporidium DNA samples.     

The role of mice in the epizootiology of Salmonella enteritidis infection on chicken layer farms.

A microbiological survey of 10 mice-infested poultry farms was conducted to determine the role of mice in the epizootiology of S. enteritidis infection. Five of the farms were rated as clean of S. enteritidis and five as contaminated based on culture results of environmental samples for S. enteritidis. Of 2103 environmental samples and 715 mice and rats tested, 5.1% and 16.2%, respectively, were culture-positive for S. enteritidis. On contaminated farms, S. enteritidis was isolated from 24.0% of the mice and 7.5% of the environmental samples, which represented 75.3% of all Salmonella isolations from mice but only 18.0% of Salmonella isolations from environmental samples on these farms. S. enteritidis was not detected in mice on clean farms. Phage types 13a and 14b were the two most frequently isolated phage types from mice and environmental samples. Although only a single phage type was isolated from single free-standing poultry houses, multiple phage types were isolated from multi-house complexes. A bacterial count from the feces of one mouse yielded 2.3 x 10(5) S. enteritidis bacteria per fecal pellet. S. enteritidis persisted at least for 10 months in an infected mouse population.     

THE PREVALENCE AND EPIZOOTIOLOGY OF SALMONELLOSIS AMONG GROUPS OF HORSES IN SOUTH EAST QUEENSLAND

Over a 3-year period, 1178 faecal samples were cultured from 462 horses admitted to the equine clinic of the University of Queensland; 185 samples were positive for salmonella yielding 213 isolations consisting of 21 serotypes. S. anatum was the predominant serotype isolated (54%) followed by S. ohio (11.27%) and S. typhimurium (9.4%). One hundred and ten horses (23.81%) were positive on one or more occasion, and 42 (9.09%) on more than one occasion.
S. anatum was the most common serotype isolated (71.43%) from the main drains in the stable block (33.57% positive samples).
The prevalence of salmonella excretors among a large non-clinic population of horses in south east Queensland was 1.65%.
Acute salmonellosis did not occur in the hospitalised animals. However, salmonellas were incriminated in 6 cases of chronic diarrhoea, which all yielded S. anatum , although the most severe involved both S. anatum and S. typhimurium , and these serotypes were isolated from multiple locations at the subsequent autopsy of 3 cases.     

Foetal pulmonary maturity in dogs: Estimated from bubble tests in amniotic fluid obtained via amniocentesis

The goal of this study was to evaluate the reliability of amniocentesis during late pregnancy to assess lung maturity in puppies using a bubble test as described by Gunston and Davey (South African Medical Journal, 54, 1978, 495). Thirty‐five bitches from eight different breeds were followed during late pregnancy before undergoing elective Caesarean (C)‐section on days 61–62 after ovulation. Bubble tests were performed the day before the C‐section (n = 11 bitches) and before the administration of aglepristone on amniotic fluid samples obtained via amniocentesis and were repeated the day of the surgery on amniotic fluid samples collected via puncture of the amniotic bags before they were opened (n = 35 bitches). No complications were observed following amniocenteses and the C‐sections. The mortality rate (2.3%) was similar to the result of other studies using the same protocol for an elective C‐section. Of the non‐contaminated samples collected the day of the C‐section, 89.6% were positive in the bubble test, which was consistent with observations of clinical maturity the day of the surgery and on the following days. In contrast, 70% of the samples collected the day before the C‐section (when progesterone concentrations were still high) were negative, suggesting that the puppies were still immature at this point in the pregnancy. Additionally, we observed a significant difference in the bubble test results before and 18 hr after the administration of aglepristone, suggesting that aglepristone may act as an inducer of the final maturation of the puppies by inactivating progesterone receptors and simulating a physiological decrease in progesterone. Finally, we confirmed the need to exclude all contaminated samples, which could lead to false‐negative results.     

Salmonella and Erysipelothrix infection in swine: a laboratory summary.

The occurrence of salmonellas and Erysipelothrix rhusiopathiae in tissues of swine was determined by bacteriologic and fluorscent antibody examination of 5,297 specimens from herds investigated for hog cholera. Of the specimens examined, 35.5% were positive for salmonellas, 21.1% were positive for E rhusiopathiae, and 8.3% were positive for both salmonellas and E rhusiopathiae.     

Characterization of coagulase negative staphylococci from cases of subclinical mastitis in dairy cattle in Kampala,Uganda

Background

Coagulase negative staphylococci (CNS) are the most common pathogens leading to subclinical mastitis (SCM) in dairy cattle in Uganda. Coagulase negative staphylococci can vary between bacterial species in how they cause disease. The aim of the study was to characterize CNS, from cows with SCM in Uganda, at the species level.

Findings

Quarter milk samples (n = 166) were collected from 78 animals with SCM. Bacteriological analyses were carried out at Makerere University, Kampala, Uganda and at the National Veterinary Institute (SVA), Uppsala, Sweden. The most common pathogens found in milk samples from cows with SCM were CNS (31.7%). Two species of CNS were found, S. epidermidis (85%) and S. haemolyticus (15%). Of the CNS isolates, 16/20 (80%) were positive for β-lactamase production (β+).

Conclusions

In milk samples from cows with SCM caused by CNS, S. epidermidis was most prevalent, followed by S. haemolyticus.