ABSTRACT. The in vitro susceptibilities of 76 isolates of Actinobacillus pleuropneumoniae collected from pigs with pleuropneumonia were tested with 12 commonly used antimicrobial drugs by an agar dilution minimal inhibitory concentration procedure according to National Committee for Clinical Laboratory Standards (NCCLS) guidelines. Field isolates had low MICs for ceftiofur, danofloxacin and penicillin. No correlation of antimicrobial resistance was related to serotype.KEY WORDS: Actinobacillus pleuropneumoniae, antimicrobial susceptibility, NCCLS, swine.J. Vet. Med. Sci. 63(3): 341-342, 2001 Actinobacillus pleuropneumoniae is the causative agent of pleuropneumonia which is one of the most important respiratory diseases in pigs worldwide. To date, at least twelve A. pleuropneumoniae serotypes (1 to 12) have been described with serotypes 1 and 5 being further subdivided into subtypes A and B [3,7]. Current bacterins provide only serotype specific protection. Differences in antimicrobial susceptibility of A. pleuropneumoniae isolates from country to country were detected for antimicrobial agents when comparing minimal inhibitory concentration (MIC) data from one country with those from another [1, 2, 5, 10, 11]. For pleuropneumonia treatment to be effective, it is important to know the antimicrobial susceptibility of A. pleuropneumoniae isolates that are isolated in each country. The objective of this study was to determine the antimicrobial susceptibility of A. pleuropneumoniae isolated from pigs in Korea using new standardized procedures for the antimicrobial susceptibility test for animal pathogens issued by the National Committee for Clinical Laboratory Standards (NCCLS) [6].Between 1995 and 1998, 76 isolates of A. pleuropneumoniae were isolated from 115 growing and finishing pigs with pleuropneumonia submitted from across Korea to the Department of Veterinary Pathology, Seoul National University. All pigs were submitted alive, and immediately upon receipt they were euthanatized for necropsy. The lung specimens were collected immediately for bacteriological culture on 5% sheep blood agar.The identification of isolates as A. pleuropneumoniae was based on Gram-staining, positive hemolysis on 5% sheep blood agar, a positive Christie-Atkins-MunchPetersen (CAMP) reaction, a requirement and detection of nicotinamide adenine dinucleotide, urease production, and xylose-and mannose-fermentation. The CAMP reaction was determined on 5% sheep blood agar, with a beta-hemolysis-producing Staphylococcus intermedius strain. Five isolates of A. pleuropneumoniae were isolated in 1995; 15 were isolated in 1996; 26 were isolated in 1997; and 30 were isolated in 1998. The serotypes of the 76 isolates of A. pleuropneumoniae tested in this study have been published: 46 were serotype 2, 20 were serotype 5, and 10 were serotype 6 [4].The following antimicrobial agents and combinations of antimicrobial agents were tested: ampicillin, amoxicillin, danofloxacin, trimethoprim-sulfamethoxazole (19:1), tiamulin, tylosin, tetracycline, pen...

The relationship between tumor necrosis factor (TNF)-alpha level, body temperature, and pulmonary lesion score was determined in 3-week-old pigs inoculated intranasally with swine influenza virus (SIV) subtype H1N2. The expression of TNF-alpha was measured in bronchoalveolar lavage (BAL) fluids by enzyme-linked immunosorbent assay and lung tissues by immunohistochemistry. In BAL fluid, TNF-alpha concentration was maximal at 1 days post-inoculation (dpi), declined markedly by 3 dpi (P<0.05) and steady thereafter. Mean rectal temperatures were above 40 degrees C for the infected groups at 1 dpi and declined markedly by 3 dpi. The body temperatures were correlated with the levels of TNF-alpha in BAL fluids from pigs experimentally infected with SIV (r(s)=0.9754, P<0.05). The pulmonary lesion scores were correlated with the means of positive cells by immunohistochemistry for TNF- alpha (r(s)=0.9949, P<0.001). The results suggest that the expression of TNF-alpha protein plays an important role in induction of pulmonary lesion and clinical sign such as fever in SIV infection.

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ABSTRACT. The aim of this study was to develop in situ hybridization for detection of Mycoplasma hyorhinis in formalin-fixed, paraffinwax-embedded tissues from pigs with polyserositis. M. hyorhinis was isolated from the spleen (2 pigs) and pericardium (1 pig). M. hyorhinis DNA was detected 16 out of 20 pigs with polyserositis. In situ hybridization produced a distinct positive signal for the M. hyorhinis p37 gene in inflammatory cells in the polyserositis. In situ hybridization developed in the present study present diagnostic tools capable of detection of M. hyorhinis in formalin-fixed, paraffin-wax-embedded tissues from the naturally infected pigs.KEY WORDS: in situ hybridization, Mycoplasma hyorhinis, swine.

The expression of myeloperoxidase (MPO) was examined in the swine influenza virus (SIV)-infected neutrophils in the lungs of pigs experimentally infected with swine influenza virus (SIV) subtype H1N2 by immunohistochemistry. Five pigs each from the infected and non-infected group were euthanized 1, 3, 5, 7, and 10 days post-inoculation (dpi). Immunohistochemical reactivity was mainly seen in neutrophils. The score for pulmonary histopathological lesions correlated with the score for MPO immunohistochemical reactivity (r ( s ) = 0.962, P < 0.01). In addition, the score for in situ hybridization of SIV nucleic acid correlated with the score for MPO immunohistochemical reactivity (r ( s ) = 0.976, P < 0.01). These results suggest neutrophils are one of the primary effector cells in the early phase of SIV infection in pigs.