Salmonella (sero)types and their resistance patterns isolated from pig faecal and post-mortem samples in 2000 - 2003

The purpose of this survey was to describe the porcine Salmonella isolates derived from faecal samples and post-mortem material (PMM) during years 2000 - 2003. Salmonella was isolated by direct inoculation on BGANO-plates (faeces, intestinal content) or sheep blood agar (organs). Antimicrobial susceptibility was tested by the agar diffusion method. Salmonella was isolated in 3.2% of all porcine submissions received at the Animal Health Service. A total of 960 salmonellae were isolated from a total of 589 submissions from 488 different herds. S. Typhimurium was the most frequently isolated serotype (N= 808, 92.6% of 873 isolates typed), and Salmonella Typhimurium DT104 was the most frequently determined phagetype (N=98, 29.6% of 333 S. Typhimurium typed). Resistance to antimicrobials occurred in 52.5% of all isolates, mainly in the multiresistant phagetype DT1 04. In less than half of the submissions (44%), other pathogens were isolated as well. In cases of clinical diarrhoea, multiple pathogens and pathogens with multiple antimicrobial resistance may be involved and therapy and preventive measures should be adjusted accordingly

Pilot experiment with the aim to reduce salmonella prevalence in pork by logistic slaughter of pigs

A pilot experiment was carried out with the aim to evaluate the possibilities and results of logistic slaughter of pigs (separate slaughter of salmonella-free and salmonella-infected pig herds) under usual circumstances in a Dutch slaughterhouse. During the experiment salmonella-free herds were delivered and slaughtered on Tuesday mornings. Herds delivered on Thursday mornings served as a control group. No significant difference could be found in the number of salmonella-positive carcasses on Tuesdays and Thursdays. This was mainly caused by contamination of carcasses by contaminated slaughter equipment; 80% of all salmonella strains on carcasses were equal to strains isolated from slaughter equipment. If these salmonella strains were not included in the results, logistic slaughter did result in a significantly lower prevalence of salmonella on carcasses on Tuesdays. It was concluded that separate slaughter of salmonella free pig herds can result in a lower salmonella prevalence on carcasses, but only if slaughter hygiene and especially cleaning and disinfection before and during processing will be improved

Comparison of an excision and a sponge sampling method for measuring salmonella contamination of pig carcasses

The aim of this study was to determine if an excision sampling method and a sponge sampling method give comparable results when trying to isolate salmonella from pig carcasses. During ten sampling days in one abattoir in total 312 carcasses were sampled; each carcass was sampled with both sampling methods to get paired observations. The number of salmonella positive excision samples (31 of 312) was significantly higher (P=0.00013) than the number of salmonella positive sponge samples (9 of 312). Sensitivity of the sponge method compared to the excision method was 6.5% and the comparability of both tests was low (kappa value was 0.08). As it seems that salmonella contamination levels of fresh pork are highly underestimated with the actually used sampling methods, the authors recommend that EU-authorities prescribe a destructive salmonella test for monitoring pig carcasses after slaughter in all EU-countries or a swab/sponge method with a comparable sensitivity

Selection of finishing pig herds with a low Salmonella prevalence for logistic slaughtering

The aim of this study was to select 50 herds with a low Salmonella-contamination rate. Per herd 40 blood samples were collected which had to be negative for antibodies against Salmonella. Infection of the pigs at the abattoir was measured by culturing tonsils for Salmonella. The results showed that not enough herds could be selected when the original criteria were applied. Less strict criteria had to be applied. We conclude from this trial that it is possible to select herds with a lower Salmonella-prevalence resulting in a lower introduction of Salmonella into the abattoir. Strict criteria must be applied to select herds with a minimal risk of being Salmonella-positive

The effect of the application of mono-lauric acid with glycerol mono-laurate in weaned piglets, on the use of antimicrobials in sow herds

The Dutch government has obliged the pig industry to reduce the use of antimicrobials at farm level with 50% by 2013. The search for alternatives for antimicrobials and other tools which can improve the health status of the farm is intensified. One example of an alternative for antimicrobials is Daafit, a combination of lauric acid and glycerol-mono-laurate, produced by the firm Daavision B.V.

Persistence of Methicillin-resistant Staphylococcus aureus (MRSA) in pig herds over a two year period

Aim of this study was to determine if a known MRSA contamination within a pig herd could persist for a period of two years. Material and Methods: 16 pig herds with a known MRSA contamination were asked to participate in this study. Per herd, five dust swabs (Sodibox®) were collected every two months for a period of two years. Samples were tested for presence of MRSA by culture and two PCR’s for confirmation of MRSA. Isolates were typed by spa- en MLVA-typing

Staphylococcus au reus (MSSA) and MRSA (ST398) isolated from post-mortem samples from pigs

In 2003 a new strain of methicillin resistant Staphylococcus aureus (MRSA), now called livestock-associated MRSA (LA-MRSA), was found in humans and in pigs. Pigs were found to be carriers of this strain of MRSA. So far, only one publication reported LA-MRSA being involved in pathological lesions in pigs: a case of exudative dermatitis in which LA-MRSA was found

Isolation of Salmonella enterica in seropositive classified finishing pig herds

The aim of this study was to assess the probability of detecting Salmonella from pen faecal samples in seropositive classified finishing pig herds. The study involved 77 herds from Denmark (20), the Netherlands (20), Greece (17) and Germany (20). The serological herd status was determined by the blood- sampling of 50 finishing pigs. Bacteriological sampling was performed by 20 pen faecal samples per herd. Over-all, 47 % of the blood samples had an OD% larger than 10 and 23 % larger than 40. Salmonella was isolated from 135 (9.3 %) pen faecal samples in 32 herds (42 %). Twenty-eight of these herds (87.5 %) had a within-herd seroprevalence larger than 50% at sample cut-off OD%\u3e10. A correlation coefficient of 0.62 was found between the proportion of culture positive- and seropositive samples in a herd at cut-off OD % \u3e 10 and of 0.58 at cut-off OD % \u3e 40. Due to the low sensitivity of culture methods, apparent ‘false positive’ serological results may well represent real infections not detected by bacteriological testing. In this study, there was an increasing probability of recovering Salmonella with increasing within-herd seroprevalence

Transmission of MRSA ST398 through the pork production chain

A distinct clone of MRSA, Multi Locus Sequence Type 398, was found in pigs and people in contact with pigs recently. In The Netherlands, a high prevalence of MRSA ST398 positive pig farms is reported. To quantifY the role of animal trade on MRSA transmission within the pig production chain, results of 51 pig farms within 19 production chains were analyzed. Fifty-five percent of the fanns were positive, including all kinds of fanns. Complete positive and complete negative chains were found. Farmswith a MRSA positive supplier had a much higher risk of being MRSA positive than farms with a MRSA negative supplier. These results indicate that trade of animals might be an important risk factor for tl1e introduction ofMRSA ST398 into pig farms