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.     

Occurrence of enteric redmouth disease in rainbow trout (Oncorhynchus mykiss) on farms in Croatia

During the spring of 1996 and autumn of 1997 unusual mortality outbreaks among rainbow trout fry and yearlings occurred at two different trout farms, resulting in mortality of 20 and 10 per cent, respectively. Generally, the affected fish, swimming at the water surface, were reluctant to eat and were dark pigmented with visible haemorrhages around and within the oral cavity. Bacterial isolates from moribund fish from both cases were identified as Yersinia ruckeri by standard biochemical tests and API 20E. The isolated strains were found to be sensitive to tetracycline, chloramphenicol, co-trimoxazole, nalidixic acid, flumequine, enrofloxacin, carbenicillin and gentamicin. Microplate agglutination assay confirmed that both isolates belonged to serotype O1. The pathogenicity of the isolated bacteria was confirmed by challenge experiment. Titres of specific antibodies were determined in the sera of survivors. The titre was highest on the 21st day postchallenge and was detectable until the 81st day.     

Phenotypic and histological expression of different genetic backgrounds in interactions between lettuce, wild Lactuca spp., L. sativa × L. serriola hybrids and Bremia lactucae

Phenotypic and histological responses of cultivated lettuce (Lactuca sativa) and wild relatives L. saligna, L.␣virosa as well as interspecific crosses derived from L. sativa × L. serriola to two races of Bremia lactucae (CS2, CS9) were investigated. With the exception of L. sativa genotypes, all accessions and hybrids expressed incomplete or complete resistance to both pathogen races, with slight differences at seedling and adult plant stages, respectively. Histological features of the interactions (development of pathogen infection structures and host hypersensitive response to attempted infection) were studied on leaf discs 48 h after inoculation. Interactions with similar phenotypic expression of resistance were characterized by significant variation in rate of development of pathogen infection structures and hypersensitive reactions. Differences found within eight Lactuca spp. accessions and hybrids challenged by two distinct pathogen races are interpreted and discussed.     

Roles of stolbur phytoplasma and <Emphasis Type="Italic">Reptalus panzeri</Emphasis> (Cixiinae,Auchenorrhyncha) in the epidemiology of Maize redness in Serbia

Maize redness (MR), a disease causing midrib, leaf and stalk reddening and abnormal ear development in maize, has been reported from Serbia, Romania and Bulgaria for 50 years. Recent epiphytotics reduced yields by 40%–90% in southern Banat, Serbia. MR was recently associated with the presence of the stolbur phytoplasma, although the epidemiology of the disease remained unknown. Diseased fields in southern Banat were surveyed for potential vectors of the phytoplasma during 2005 and 2006, and high populations of Reptalus panzeri were found. In affected fields, 20% of the R. panzeri individuals and 85% of symptomatic maize plants carried the stolbur phytoplasma. When stolbur phytoplasma-infected R. panzeri were introduced into insect-free mesh cages containing healthy maize plants, midrib and leaf reddening developed on 48% of plants and stolbur phytoplasma was detected in 90% of the symptomatic plants. No symptoms or phytoplasma-positive plants were found in cages without insects. These data indicate that MR symptoms are associated with the stolbur phytoplasma. Reptalus panzeri is both abundant in affected fields and can transmit the stolbur phytoplasma, indicating the insect is likely to be a major vector of MR.     

Analysis of genetic diversity among Macrophomina phaseolina (Tassi) Goid. isolates from Euro-Asian countries

Journal of Plant Diseases and Protection - The study assessed the genetic variability among Macrophomina phaseolina (Tassi) Goid. isolates originating from six different countries (Turkey,...     

Genetic variability and virulence among Verticillium albo-atrum isolates from hop

Verticillium wilt, caused by Verticillium albo-atrum or V. dahliae, is an important disease of many worldwide crop species. In Europe, V. albo-atrum isolates infecting hop express different levels of virulence, inducing mild or lethal disease syndromes, and it is therefore an attractive model for studying the virulence of this pathogen. In this work, eleven amplified fragment length polymorphism (AFLP) primer combinations were used to analyze genetic variability among 55 V. albo-atrum hop isolates from four European hop growing regions, as well as isolates from other hosts and V. dahliae isolates. Cluster analysis divided V. albo-atrum and V. dahliae isolates into two well-separated groups. Within the V. dahliae cluster, isolates were separated without host specific grouping, although no host adapted isolates were included. In V. albo-atrum, the alfalfa isolates were distinct from isolates of other hosts, where a high association with virulence was observed in hop and tomato isolates. All lethal hop isolates were genetically different from mild hop isolates. The lethal hop isolates from England and Slovenia expressed the same virulence phenotype, although they showed a different AFLP pattern. The mild hop isolates formed two subgroups, to which isolates clustered irrespective of geographical location. These data suggest multiple origins of V. albo-atrum hop isolates, and the possible appearance of new virulent isolates in the future in other hop growing regions.     

Study of the genetic variability of porcine circovirus type 2 detected in Serbia and Slovenia

Recent variants of porcine circovirus type 2 (PCV2) were obtained from tissues of domestic pigs with porcine circovirus associated disease and from randomly selected wild boar samples from Serbia and Slovenia. A 450-base-pair nucleotide sequence was obtained by PCR from the ORF2. The derived nucleotide and amino acid sequences were aligned and compared to the corresponding region of closely related PCV2 sequences determined in previous years and retrieved from the GenBank. The 30 Serbian and 17 Slovenian PCV2 sequences clustered into three previously determined genotypes (PCV2a: 7), (PCV2b: 38) and (PCV2d: 2). Three major variable regions, concerning 29 amino acid position substitutions within the ORF2, were observed, which further supports the segregation of the detected strains into three separate genotypes. This study indicates that PCV2b is the predominant genotype in Serbia and Slovenia and the detected PCV2 strains are closely related to those previously described in Europe and in other parts of the world.     

N. femoralis, N. obturatorius and N. ischiadicus: deviation in creation in the dogs

Two hundred and twelve dog cadavers belonging to different breeds were examined, to investigate the formation of the femoral, obturator and the sciatic nerve. Besides the commonly described formation patterns of the mentioned nerves, some variations were also found. These variations were not gender-related, but on the other hand we discovered a certain correlation between the variations appearing in the formation of the femoral, obturator and the sciatic nerve. In 74.05% of cases, the femoral nerve was formed from ventral branches of the 4th, 5th and 6th lumbar nerve, and 16.98% of the dogs had the nerve formed from ventral branches of the 3rd, 4th and 5th lumbar nerve. Many dogs (i.e. 2.30%) had the femoral nerve formed from the ventral branches of the 5th, 6th and 7th, the 3rd, 4th, 5th and 6th or the 4th, 5th, 6th and 7th lumbar nerve, respectively. In 1.88% of dogs in particular, the femoral nerve was formed from ventral rami of the 4th and 5th lumbar nerve. In 66.98% of the examined dogs, the obturator nerve was formed from the ventral branches of the 4th, 5th and 6th lumbar nerve, followed by 16.59% of the dogs with the obturator nerve formed from the ventral rami of the 4th and 5th lumbar nerve and 9.43% of dogs in which the nerve was formed from the ventral branches of the 5th and 6th lumbar nerve. In 4.71% of dogs, the obturator nerve was formed from the ventral rami of the 4th, 5th, 6th and 7th lumbar nerve, while only 2.30% of the examined dogs had the same nerve formed from the ventral branches of the 5th, 6th and 7th lumbar nerve. The sciatic nerve was formed from ventral branches of the 6th and 7th lumbar nerve and the 1st sacral nerve in 86.79% of the dogs. In 5.18% of cases, the same nerve was formed from a junction of the ventral branches of the 7th lumbar and the 1st and 2nd sacral nerve, and, in the same percentage of cases, it was formed from a junction of ventral branches of the 6th and 7th lumbar nerve and the 1st and 2nd sacral nerve. In 2.83% of the dogs, it was formed from a junction of the ventral branches of the 6th and 7th lumbar and the 1st sacral nerve. The correlation of variations established in the formation of the femoral, obturator and the sciatic nerve was not statistically significant.     

Comparison of a commercial ELISA with the modified agglutination test for the detection of Toxoplasma gondii infection in naturally exposed sheep

Surprisingly few commercial ELISAs are available for the detection of Toxoplasma gondii infection in animals, and none for use in sheep have been evaluated. We thus compared the Bommeli Diagnostics ELISA Toxotest for the detection of T. gondii antibodies in ruminants with the reference modified agglutination test (MAT) in a series of 180 sheep sera. ELISA results were analysed at two cut-off levels (30%, comprising both weakly positive and positive results, and 100%, comprising only positive results), and compared with MAT at three cut-off levels (titre of 1 : 25, 1 : 50 and 1 : 100). The results showed a moderate agreement of ELISA at both cut-offs (kappa = 0.46 and 0.51) with MAT at a cut-off titre of 1 : 100. However, the specificity and positive predictive value were above 95% only at an ELISA cut-off of 100%, indicating its potential as a diagnostic test, particularly in areas with a high prevalence of infection. On the other hand, lower sensitivity and negative predictive value limit its value as a screening test. Thus, the ELISA Toxotest may be used for quick diagnosis of T. gondii infection in sheep in the field, i.e. for the differential diagnosis of ovine abortion storms.