Usefulness of molecular typing methods for epidemiological and evolutionary studies of Staphylococcus aureus isolated from bovine intramammary infections.

In cattle, Staphylococcus aureus is a major pathogen of increasing importance due to its association with intramammary infections (IMIs), which are a primary cause of antibiotic use on farms and thus of the rise in antibiotic resistance. Methicillin-resistant S. aureus (MRSA), which are frequently isolated from cases of bovine mastitis, represent a public health problem worldwide. Understanding the epidemiology and the evolution of these strains relies on typing methods. Such methods were phenotypic at first, but more recently, molecular methods have been increasingly utilized. Multiple-locus variable number tandem repeat analysis (MLVA), a high-throughput molecular method for determining genetic diversity and the emergence of host- or udder-adapted clones, appears to be the most useful PCR-based method. Despite the difficulties present in reproducibility, interlaboratory reliability, and hard work, it is agreed that pulsed-field gel electrophoresis (PFGE) remains the gold standard, particularly for short-term surveillance. Multilocus sequence typing (MLST) is a good typing method for long-term and global epidemiological investigations, but it is not suitable for outbreak investigations. Staphylococcal protein A (spa) typing is the most widely used method today for first-line typing in the study of molecular evolution, and outbreaks investigations. Staphylococcal cassette chromosome mec (SCCmec) typing has gained popularity for the evolutionary analysis of MRSA strains. Whole-genome sequencing (WGS) and DNA microarrays that represent relatively new DNA-based technologies, provide more information for tracking antibioresistant and virulent outbreak strains. They offer a higher discriminatory power, but are not suitable for routine use in clinical veterinary medicine at this time. Descriptions of the evolution of these methods, their advantages, and limitations are given in this review.

Univariate associations between housing, management, and facility design factors and the prevalence of lameness lesions in fourteen small-scale dairy farms in Northeastern Algeria.

BACKGROUND AND AIM: This cross-sectional study aimed to analyze the associations between different types of housing, management, and facilities on the prevalence of lame, causing lesions in smallholder dairy farms in Algeria. MATERIALS AND METHODS: The on-site investigation took place between December 2012 and May 2015. All cows were locomotion scored on a four-point scale, and foot lesions causing lame were diagnosed and recorded. Factors related to the farm and the cows' conditions were also assessed. The association between the possible risk factors and lame lesions was assessed using univariate analysis. RESULTS: Of the 349 cows evaluated, 13% were lame (lameness score ≥2), with higher lameness values recorded for the hind feet than for the forefeet. Cows without lameness were classified as healthy. The two most frequent lesion diagnoses observed in lame cows were interdigital dermatitis/heel horn erosion (ID/HE; 39%) and interdigital phlegmon (IP; 35%), followed by traumatic lesions (T; 11%), digital dermatitis (DD; 8.7%), and laminitis-related diseases (L; 6.5%). The risk of being lame was increased in large herds with cows of the Holstein breed, and those in the third parity and above. Tie housing, concrete floor, concentrate feeding, zero-grazing, and the use of foot trimming occasionally were associated with increased risk for the presence of lame lesions. The region and footbathing frequency had no association with the prevalence of lame lesions (p≥0.05). CONCLUSION: These results have important implications; they indicate that several aspects of housing, management, and facility design are common protective factors for the prevalence of lame lesions. These factors should be maintained correctly to not only reduce the number of lame cows in these herds but also decrease the direct and indirect costs associated with cases of lameness.

MALDI-TOF MS identification of ticks of domestic and wild animals in Algeria and molecular detection of associated microorganisms.

Recent studies have reported the reliability of MALDI-TOF MS for arthropod identification, including fresh or alcohol-preserved ticks based on leg-derived mass spectra. The aim of this study was to evaluate the performance of MALDI-TOF MS for the identification of alcohol-preserved Algerian ticks collected from different domestic and wild hosts. Secondly, we conducted a molecular survey to detect the presence of bacterial DNA in all ticks that were previously subjected to MALDI-TOF MS. A total of 2635 ixodid and 1401 argasid ticks belonging to 9 distinct species were collected in nine different regions of northeastern Algeria. The legs of 230 specimens were subjected to MALDI-TOF MS assays. Spectral analysis revealed intra-species similarity and inter-species specificity for the MS spectra, which was consistent with the morphological identification. Blind tests against the in-lab database revealed that 93.48% of the tested specimens were correctly identified. The accuracy of the morphological and MALDI-TOF MS identifications was validated by sequencing the 12S ribosomal RNA gene (rRNA) for 33 specimens and all the ticks were correctly identified. The quantitative PCR screening showed that for 219 tested ticks, 15 were positive for Rickettsia spp., 8 for Borrelia spp. and 17 for Anaplasmataceae. The PCR tests were negative for Coxiella burnetii and Bartonella spp. This study supports MALDI-TOF MS being a reliable tool for the identification of arthropods and brings new data that sheds light on tick species diversity and tick-borne diseases in Algeria.