Antimicrobial Resistance and Multilocus Sequence Types of Finnish Campylobacter jejuni Isolates from Multiple Sources.

Antimicrobial susceptibility was determined for 805 domestic Campylobacter jejuni isolates obtained from broilers (n = 459), bovines (n = 120), human patients (n = 95), natural waters (n = 80), wild birds (n = 35) and zoo animals/enclosures (n = 16) with known multilocus sequence types (MLST) for 450 isolates. The minimum inhibitory concentration (MIC) values for erythromycin, tetracycline, streptomycin, gentamicin and the quinolones ciprofloxacin and nalidixic acid were determined with the VetMIC method. MICs were compared with MLST types to find possible associations between sequence type and resistance. The proportions of resistant isolates were 5% (broilers), 6.3% (natural waters), 11.4% (wild birds), 11.6% (human patients), 16.7% (bovines) and 31.3% (zoo). The most common resistance among the human and bovine isolates was quinolone resistance alone while resistance to streptomycin alone was most often detected among the broiler isolates and tetracycline resistance was most commonly observed in the wild bird, water and zoo isolates. No or negligible resistance to erythromycin or gentamicin was detected. In all data, 12/26 of the tetracycline-resistant isolates were also resistant to streptomycin (P < 0.001) and the clonal complex (CC) ST-1034 CC showed a high proportion of 75% (9/12) of tetracycline-resistant isolates, most originating from the zoo and broilers with closely associated MLST types from these sources. No association between quinolone resistance and MLST type was seen. The low percentage of resistant isolates among the domestic Campylobacter infections is most probably due to the long-term controlled use of antimicrobials. However, the higher percentage of tetracycline resistance observed among the zoo isolates could present a risk for zoo visitors of acquisition of resistant C. jejuni. The resistance pattern of tetracycline and streptomycin most often found in ST-1034 CC could indicate a common resistance acquisition mechanism commonly present in this CC. Overall, MLST typing was found to be a useful method in recognition of potential genetic lineages associated with resistance.

A combination of MLST and CRISPR typing reveals dominant Campylobacter jejuni types in organically farmed laying hens.

AIM: To elucidate the Campylobacter jejuni population in organically farmed laying hens in Finland, multilocus sequence typing (MLST) was combined with characterization of clustered regularly interspaced short palindromic repeat (CRISPR) sequences. METHODS AND RESULTS: A total of 147 Camp. jejuni isolates, collected from organically farmed laying hens from 18 farms in 2003-2004, were previously analysed by pulsed-field gel electrophoresis. In the present study, subsets of the isolates were further analysed by MLST and CRISPR sequences. Fourteen STs were found by MLST. ST-50 (27%, 7/18 farms), ST-3272 (20%, 8/18 farms), ST-45 (12%, 7/18 farms) and ST-356 (12%, 5/18 farms) were the most common STs. CRISPR types were identical among all isolates of ST-50 (ST-21 clonal complex (CC)) and the most variable among ST-45 (ST-45 CC). CONCLUSIONS: ST-3272 (UA), a common ST in this study, has been infrequently detected in other hosts. Other major STs (ST-50 and ST-45) have been common in several hosts such as conventional poultry and bovines. CRISPR typing provided additional discrimination between isolates of certain dominant STs and could be useful in further epidemiological studies. SIGNIFICANCE AND IMPACT OF THE STUDY: This study gives new information about MLST and CRISPR types of Camp. jejuni among organically farmed laying hens.

Rapid quantitation of DNA spot hybridization by flatbed scintillation counting.

The flatbed scintillation counting system (Betaplate) was used for quantitative measurement of the radioactive hybridization signal in detection of adenovirus and papillomavirus DNA in clinical specimens. In this method, 96 samples on a nylon membrane can be handled as a single entity throughout the hybridization and counting procedure. The technique is sensitive, rapid, and convenient in routine use when compared with conventionally applied methods for the numerical analysis of hybridization results. The assay principle allows simultaneous testing of large numbers of specimens.