In vitro antimicrobial susceptibility of 183 Pseudomonas aeruginosa strains isolated from dogs to selected antipseudomonal agents

During the years from 1993 to 2000, 183 strains of Pseudomonas aeruginosa were isolated from different pathological specimens originating from dogs. Antimicrobial susceptibility patterns against 10 antipseudomonal agents were obtained on 183 P. aeruginosa strains. In vitro antimicrobial susceptibility testing was performed using the disk diffusion method (Kirby-Bauer). Antimicrobial susceptibility profiles showed that among beta-lactam antibiotics, imipenem was the most active compound. Out of the 183 strains tested, 96.7% were sensitive to imipenem. Cefoperazone showed good in vitro activity against 86.9% of the tested strains. Against ceftazidime, 77.0% of strains showed sensitivity. An old penicillin, carbenicillin, gave only 71.6% sensitive strains. Sensitivity to amikacin was 87.4% and it was 83.1% to gentamicin. Pipimedic acid, a first-generation quinolone, was the least active compound of all those tested, 47.0% were resistant. The in vitro sensitivity against enrofloxacin showed that 71.0% strains were sensitive and 26.2% showed resistance. Almost all strains tested, 93.4%, were susceptible to ciprofloxacin and marbofloxacin. Besides imipenem, the quinolone antibiotics, marbofloxacin and ciprofloxacin were the most effective against P. aeruginosa strains isolated from dogs.     

Distribution and characterization of class 1 integrons in Salmonella enterica serotype Gallinarum biotype Gallinarum

Fowl typhoid caused by Salmonella enterica subsp. enterica serotype Gallinarum biotype Gallinarum is the most important chicken disease in Korea. Due to appearance of new or multiple antibiotics resistances in the recently isolated strains, it was difficult to control the disease using antibiotics in our country. Therefore, the prevalence and genetic contents of class 1 integrons in biotype Gallinarum isolated between 1992 and 2001 were investigated by PCR and direct sequencing, respectively. Out of 90 strains, 35 (39%) carried class 1 integrons. The 1.0, 1.6 and 2.0kbp amplicons were amplified in 32 strains (36%), 2 strains (2%) and 1 strain (1%), respectively. The 1.0, 1.6 and 2.0 kbp amplicons contained one (aadA1a), two (aadB-aadA1b) and three cassettes (dhfrXII-orfF-aadA2), respectively, providing resistances against aminoglycosides (aadA1a, aadA1b, aadB, and aadA2) and trimethoprim (dhfrXII). The integron-carrying strains of biotype Gallinarum appeared in 1996 and acquired additional cassettes in 2000. Although the resistances to ampicillin, tetracycline and chloramphenicol are unrelated to class 1 integrons, relatively high prevalence of integron in biotype Gallinarum may be a dormant threat to the chemotherapy of the disease in the near future because of potency to acquire additional antibiotics resistances.     

An outbreak of fatal hemorrhagic pneumonia caused by Streptococcus equi subsp. zooepidemicus in shelter dogs

An outbreak of fatal hemorrhagic pneumonia with 70~90% morbidity and 50% mortality occurred in an animal shelter in Yangju, Gyeonggi Province, Korea. Clinically, the affected dogs showed severe respiratory distress within 48 h after arriving in the shelter. The dead were found mainly with nasal bleeding and hematemesis. At necropsy, hemothorax and hemorrhagic pneumonia along with severe pulmonary consolidation was observed, though histopathological analysis showed mainly hemorrhagic bronchopneumonia. Lymphoid depletion was inconsistently seen in the spleen, tonsil and bronchial lymph node. Gram-positive colonies were shown in blood vessels or parenchyma of cerebrum, lung, liver, spleen, and kidney. Also, Streptococcus (S.) equi subsp. zooepidemicus was isolated from the various organs in which the bacterium was microscopically and histologically detected. In addition, approximately 0.9 Kb specific amplicon, antiphagocytic factor H binding protein, was amplified in the bacterial isolates. In this study, we reported an outbreak of canine hemorrhagic bronchopneumonia caused by S. equi subsp. zooepidemicus in an animal shelter in Yangju, Korea.     

Mitochondrial transmembrane potential and reactive oxygen species generation regulate the enhanced effect of CCCP on TRAIL-induced SNU-638 cell apoptosis

TRAIL is a member of the tumor necrosis factor family and engages apoptosis via recruitment and rapid activation of caspase-8. This study investigated the effect of carbonyl cyanide m-chlorophenylhydrazone (CCCP), a classic uncoupler of oxidative phosphorylation, on TRAIL-induced apoptosis in SNU-638 cells derived from human gastric cancer cells. It was found that treatment with CCCP followed by incubation with TRAIL markedly enhanced apoptosis by 2 fold compared with treatment with TRAIL alone. This effect was accompanied by reduction in mitochondrial transmembrane potential and generation of reactive oxygen species. This sensitization was inhibited by N-acetyl-l-cysteine, which restored the mitochondrial transmembrane potential and reduced reactive oxygen species generation. Treatment with N-acetyl-L-cysteine also inhibited expression of apoptotic proteins such as Bax and Smac and abrogated caspase-8 activation. Moreover, treatment with N-acetyl-L-cysteine prior to induction with TRAIL increased expression of the anti-apoptotic Bcl-2 protein. These data indicate that CCCP enhanced TRAIL-induced apoptosis by dissipation of mitochondrial transmembrane potential and reactive oxygen species, suggesting that treatment with CCCP combined with that with TRAIL can be an efficient method to induce death of tumor cells, particularly cells that are resistant to TRAIL-induced apoptosis.     

Echinochrome A Treatment Alleviates Atopic Dermatitis-like Skin Lesions in NC/Nga Mice via IL-4 and IL-13 Suppression

Atopic dermatitis (AD) is a chronic inflammatory skin disease in which skin barrier dysfunction leads to dryness, pruritus, and erythematous lesions. AD is triggered by immune imbalance and oxidative stress. Echinochrome A (Ech A), a natural pigment isolated from sea urchins, exerts antioxidant and beneficial effects in various inflammatory disease models. In the present study, we tested whether Ech A treatment alleviated AD-like skin lesions. We examined the anti-inflammatory effect of Ech A on 2,4-dinitrochlorobenzene (DNCB)-induced AD-like lesions in an NC/Nga mouse model. AD-like skin symptoms were induced by treatment with 1% DNCB for 1 week and 0.4% DNCB for 5 weeks in NC/Nga mice. The results showed that Ech A alleviated AD clinical symptoms, such as edema, erythema, and dryness. Treatment with Ech A induced the recovery of epidermis skin lesions as observed histologically. Tewameter^® and Corneometer^® measurements indicated that Ech A treatment reduced transepidermal water loss and improved stratum corneum hydration, respectively. Ech A treatment also inhibited inflammatory-response-induced mast cell infiltration in AD-like skin lesions and suppressed the expression of proinflammatory cytokines, such as interferon-γ, interleukin-4, and interleukin-13. Collectively, these results suggest that Ech A may be beneficial for treating AD owing to its anti-inflammatory effects.     

Anaesthetic efficacy and physiological responses to clove oil-anaesthetized kelp grouper Epinephelus bruneus

The efficacy of clove oil as an anaesthetic and at producing a physiological response (plasma cortisol and glucose) was evaluated in the kelp grouper, Epinephelus bruneus . To acquire complete anaesthesia in less than 3 min and recovery in <10 min, three doses of clove oil were tested at 18, 22 and 26 °C. Although higher anaesthetic doses resulted in shorter induction times and longer recovery times, and a lower temperature resulted in longer anaesthesia induction and slower recovery, we found the optimal dose and administering temperature of clove oil to be 250–300 mg L⁻¹ at water temperature of 18 °C, 150–200 mg L⁻¹ at water temperature of 22 °C and 50–100 mg L⁻¹ at water temperature of 26 °C respectively. Following the administration of 150 mg L⁻¹ of clove oil at 22 °C, the plasma cortisol level was highest (4.24 ± 1.571 μg dL⁻¹) after 12 h and the plasma glucose was highest (92.7 ± 9.61 mg dL⁻¹) after 2 h. These results should be useful to the aquaculture industry, where anaesthesia is necessary for a range of activities.     

Epidemiological and microbiological study of an outbreak of infectious keratoconjunctivitis in sheep

After several thousand sheep had been imported from Australia and New Zealand to Croatia during 1995, many native sheep that had been in contact with the imported animals acquired a severe ocular disease closely resembling infectious keratoconjunctivitis. In affected flocks glucose-fermenting mycoplasma were isolated from 48 per cent of conjunctival swabs and Branhamella ovis from 58 per cent. Twelve of 42 culturally and biochemically identical isolates were identified as Mycoplasma conjunctivae by polymerase chain reaction. From the conjunctivae of two animals M conjunctivae and M arginini were isolated in mixed culture. For many reasons most farmers removed the imported animals from their flocks and only sporadic cases of the disease were recognised in 1996. At the end of 1997, six flocks which were clinically free of the disease but had been affected during 1995, and five flocks with no history of the severe ocular disease were examined clinically and microbiologically, and were found to be free of M conjunctivae infection. At the time, B ovis was cultured almost exclusively from sheep originating from flocks which had been affected during 1995 and/or 1996. It was usually isolated in pure culture or as the predominant bacterial species, and was often accompanied by mild conjunctivitis. There were no microbiologically confirmed new cases of infectious keratoconjunctivitis during 1998 and 1999.     

Quantitative measurement of influenza virus replication using consecutive bronchoalveolar lavage in the lower respiratory tract of a ferret model

The ferret is an established animal model of influenza virus infection. Although viral replication in the upper respiratory tract is usually measured with consecutively collected nasal washes, daily evaluation of viral replication in the lung is limited because a large numbers of ferrets need to be sacrificed at consecutive time points. To overcome this limitation, we performed a virus quantification assay using bronchoalveolar lavage (BAL) fluid. This non-invasive BAL technique allows consecutive quantification of virus replication in the lungs of living ferrets. Our method can be used for the longitudinal evaluation of virus tropism in the lower respiratory tract.