BACTERIOLOGIE

Escherichia coli
• PCR detection and identification of virulence factors from Escherichia coli strains causing neonatal diarrhea
• Enterotoxigenic Escherichia coli infection in pigs and its diagnosis
Clostridium difficile
• Diagnosis and treatment of Clostridium difficile neonatal diarrhea
Mycoplasma hyopneumoniae
• A meta-analysis comparing the effect of vaccines against Mycoplasma hyopneumoniae on daily weight gain in pigs

PCR detection and identification of virulence factors from Escherichia coli strains causing neonatal diarrhea
ROUILLARD T, LE GUENNEC J, MOALIC PY
Rev Méd Vét 2002 153: 261-268
ETEC (enterotoxigenic Escherichia coli) are the most common pathogens causing diarrhea in piglets. A PCR technique was used to test and identify the different virulence factors (STb, STa, LTa) produced by ETEC strains as well as the different fimbrial adhesins (K88, K99, F41, F107). ETEC strains were isolated mostly from the ileum of diarrheic piglets and also from their colon. The STb gene coding for the same toxin had the highest prevalence (30,5% of piglets) followed by STa (11.9%). The latter was always found associated with the fimbrial adhesin K99. Only K99 and K88 were detected with K88 as the most prevalent adhesin (12%). STb gene alone was detected in 22% of piglets. A majority of piglets were tested positive for 2 to 4 virulence factors. Previous studies showed similar results although they also reported a higher number of adhesins in ETEC strains.

Enterotoxigenic Escherichia coli infection in pigs and its diagnosis
FRANCIS DH
J Swine Health Prod. 2002 10: 171-175
What is currently known about ETEC (enterotoxin Escherichia coli) is reported in this paper. The author considers different aspects of an ETEC infection: the role of fimbrial adhesins and enterotoxins, the relation between age, lineage and susceptibility to ETEC strains, the role of IMTGP (mucine-type sialoglycoprotein, the K88a and F18 receptor on porcine enterocyte) and the different methods of analysis (ELISA, IFA and PCR) with their flaws.

Diagnosis and treatment of Clostridium difficile neonatal diarrhea
LEBRET A
Porc Magazine 2002 355: 71-73
Neonatal diarrhoea in piglets due to Clostridium difficile is becoming a major cause for concern in France. The pathogen is a well known causative agent of diarrhoea in humans but is relatively new in swine. In America, Clostridium difficile has been under close scrutiny and was the only pathogen detected in 29 % (year 2000) and 42% (year 2001) of piglets analysed and suffering from diarrhoea. The diarrhoea typically occurs in one week-old piglets and is characterized by yellowish liquid stool. There is a high morbidity rate among piglets but a relatively low mortality (10%). The infection is diagnosed by an ELISA test which detects A and B toxins in collected diarrhoea. To date, 3 types of treatment and preventive measures may be recommended: 1) yeasts administered to the sow or piglets which control the proliferation of the bacteria in the intestinal flora, 2) antibiotics such as bacitracin in America (no market authorization in France) and tiamulin in France which are being tested, 3) immunization of sows (oral administration of antitoxins and 'English soup', i.e. contamination of sows).

A meta-analysis comparing the effect of vaccines against Mycoplasma hyopneumoniae on daily weight gain in pigs
JENSEN CS, ERSBOLL AK, NIELSEN JP
Prev Vet Med 2002 54: 265-278
A meta-analysis was conducted in order to assess the effects of vaccination against a causative agent of swine enzootic pneumonia (Mycoplasma hyopneumoniae) on ADWG (average daily weight gain). The three commercial vaccines currently available against the infectious agent are Stellamune®, Suvaxyne® and Hyoresp®. Out of the sixty-three studies published, 14 were finally kept for analysis as they met all the inclusion criteria. The variables of the meta-abalysis were ADWG, trial, treatment, trial size, vaccination status, housing system and vaccination schedule. An average 21g increase in ADWG was calculated in vaccinated pigs compared to non vaccinated pigs. Other variables had no significant impact on ADWG.