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Agar Containing (agar + containing)
Selected AbstractsApplication of Congo Red agar for detection of Streptococcus dysgalactiae isolated from diseased fishJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2009M. Abdelsalam Summary The strong clinical similarity between Lancefield group C Streptococcus dysgalactiae subsp. dysgalactiae (GCSD) and Lactococcus garvieae infections, characterized by development of necrotic lesions in the caudal peduncle of infected fish, has hindered differentiation of these two strains, making rapid and accurate diagnosis of diseased fish in fish farms difficult. GCSD from diseased fish were presumptively identified and isolated using Todd-Hewitt agar containing 30 ,g ml,1 of Congo Red dye (TH-CR). TH-CR agar was also used to detect and presumptively identify the GCSD obtained from artificially or naturally infected fish. Orange GCSD colonies distinct from the L. garvieae colonies were observed on the TH-CR agar; thus, TH-CR agar can be used to detect and identify GCSD isolated from infected fish. [source] Selecting for development of fluoroquinolone resistance in a Campylobacter jejuni strain 81116 in chickens using various enrofloxacin treatment protocolsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010K. Stapleton Abstract Aims:, To determine the effect of various enrofloxacin dose regimes on the colonization and selection of resistance in Campylobacter jejuni strain 81116P in experimentally colonized chickens. Methods and Results:, Two experiments were undertaken, in which 14-day-old chickens were colonized with 1 × 107,1 × 109 CFU g,1Camp. jejuni strain 81116P and then treated with enrofloxacin at 12,500 ppm in drinking water for various times. Caecal colonization levels were determined at various time-points after start-of-treatment, and the susceptibility of recovered isolates to ciprofloxacin was monitored. Resistance was indicated by growth on agar containing 4 ,g ml,1 ciprofloxacin, MICs of 16 ,g ml,1 and the Thr86Ile mutation in gyrA. Enrofloxacin at doses of 12,250 ppm reduced Camp. jejuni colonization over the first 48,72 h after start-of-treatment. The degree of reduction in colonization was dose, but not treatment time, dependent. In all cases, maximal colonization was re-established within 4,6 days. Fluoroquinolone-resistant organisms were recoverable within 48 h of start-of-treatment; after a further 24 h all recovered isolates were resistant. In contrast, a dose of 500 ppm enrofloxacin reduced colonization to undetectable levels within 48 h, and the treated birds remained Campylobacter negative throughout the remaining experimental period. By high pressure liquid chromatography, for all doses, the maximum concentrations of enrofloxacin and ciprofloxacin in the caecal contents were detected at the point of treatment completion. Thereafter, levels declined to undetectable by 7 days post-treatment withdrawal. Conclusions:, In a model using chickens maximally colonized with Camp. jejuni 81116P, treatment with enrofloxacin, at doses of 12,250 ppm in drinking water, enables the selection, and clonal expansion, of fluoroquinolone-resistant organisms. However, this is preventable by treatment with 500 ppm of enrofloxacin. Significance and impact of the study:, Treatment of chickens with enrofloxacin selects for resistance in Camp. jejuni in highly pre-colonized birds. However, a dose of 500 ppm enrofloxacin prevented the selection of resistant campylobacters. [source] Antimicrobial-resistant faecal Escherichia coli in wild mammals in central Europe: multiresistant Escherichia coli producing extended-spectrum beta-lactamases in wild boarsJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2010I. Literak Abstract Aims:, To determine the presence of antibiotic-resistant faecal Escherichia coli in populations of wild mammals in the Czech Republic and Slovakia. Methods and Results:, Rectal swabs or faeces collected during 2006,2008 from wild mammals were spread on MacConkey agar and MacConkey agar containing 2 mg l,1 of cefotaxime. From plates with positive growth, one isolate was recovered and identified as E. coli. Susceptibility to 12 antibiotics was tested using the disk diffusion method. Resistance genes, class 1 and 2 integrons and gene cassettes were detected in resistant isolates by polymerase chain reaction (PCR). Extended-spectrum beta-lactamases (ESBL) were further characterized by DNA sequencing, macrorestriction profiling and determination of plasmid sizes. Plasmid DNA was subjected to EcoRV digestion, transferability by conjugation and incompatibility grouping by multiplex PCR. The prevalence of resistant isolates was 2% in small terrestrial mammals (rodents and insectivores, nE. coli = 242), 12% in wild ruminants and foxes (nE. coli = 42), while no resistant isolates were detected in brown bears (nE. coli = 16). In wild boars (Sus scrofa) (nE. coli = 290), the prevalence of resistant isolates was 6%. Class 1 and 2 integrons with various gene cassettes were recorded in resistant isolates. From wild boars, five (2%, nrectal smears = 293) multiresistant isolates producing ESBL were recovered: one isolate with blaCTX-M-1 + blaTEM-1, three with blaCTX-M-1 and one with blaTEM-52b. The blaCTX-M-1 genes were carried on approx. 90 kb IncI1 conjugative plasmids. Conclusions:, Antibiotic-resistant E. coli occured in populations of wild mammals in various prevalences. Significance and Impact of the Study:, Wild mammals are reservoirs of antibiotic-resistant E. coli including ESBL-producing strains which were found in wild boars. [source] Bioconversion of 3,-acetoxypregna-5,16-diene-20-one to androsta-1,4-diene-3,17-dione by mixed bacterial cultureLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2002S. Patil Aims:,To isolate a bacterium capable of degrading 3,-acetoxypregna-5,16-diene-20-one (16-DPA) to androsta-1,4-diene-3,17-dione (ADD) and to decipher the biodegradation pathway. Methods and Results:,Isolation on mineral salt agar containing 16-DPA as sole carbon source yielded two bacteria identified as Pseudomonas diminuta and Comamonas acidovorons. These bacteria failed to degrade 16-DPA individually in pure cultures but converted 16-DPA to ADD in a mixed culture. The intermediates accumulated during the bioconversion were identified as pregna-4,16-diene-3,20-dione and pregna-1,4,16-triene-3,20-dione. Conclusions:,The degradation pattern of 16-DPA by mixed bacterial culture revealed the reaction sequence as (i) cleavage of C-3 acetyl function, (ii) dehydrogenation at C-1 and C-2 positions and (iii) cleavage of C-17 side-chain. Significance and Impact of the Study:,The present work opens a new approach towards the production of a female sex hormone precursor and elucidates the biodegradation pathway of 16-DPA by mixed bacterial culture. [source] | ||||||||||