Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
Spread of livestock associated MRSA CC398 in German dairy herds
Schnitt, A.; Lienen, T.; Wichmann...
Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
Read
Objectives: Livestock associated methicillin resistant Staphylococcus aureus (LA-MRSA) often belong to clonal complex (CC) 398 and may colonize and infect different animal species including humans (Cuny et al 2015). In both, animals and humans, LA-MRSA were rarely associated with clinical infections. In dairy cows, MRSA prevalence is low especially in comparison to pigs (Schnitt and Tenhagen 2019). However, LA-MRSA ST398 can cause mastitis in dairy cows (Falk 2018). Mastitis caused by MRSA is a problem in veterinary medicine, since most antibiotics approved for mastitis and dry cow therapy are β-lactams. Therefore, MRSA monitoring and prevention strategies are needed for dairy herds. This study aimed to determine the occurrence and spread of LA-MRSA on preselected German dairy farms.
Materials and methods: Based on previous phenotypic MRSA detection, 20 German dairy herds were selected and visited in 2018-19. Eight farms used automatic milking systems and 12 farms used milking parlours. From dairy cows, quarter milk samples (QMS) and bulk tank milk (BTM) was collected. Additionally, swab samples from calves, heifers, dust, teat liners, pigs, farm personnel and suckers from automatic calf feeders were analysed. In total, 3396 samples were screened for the presence of MRSA using a two-step selective enrichment protocol. All presumptive MRSA isolates were further analysed by MALDI-TOF, mecA/mecC PCR, spa-typing, SCCmec-typing and certain isolates were selected for next generation sequencing (NGS). A structured questionnaire and on farm observations were used to collect data on milking hygiene, biosecurity and general herd management.
Results: Prevalence: MRSA prevalence was 23.6% (47/199) in milk-fed calves, 13.6% (26/191) in samples from heifers, 8.6% (16/187) in post-weaning calves and 7.9% (47/595) of cows carried MRSA in QMS. In total, 68/2384 (2.9%) QMS were tested positive, indicating that multiple quarters were affected in some cows. As an indicator for mastitis, the average somatic cell count (geometric mean) was higher in QMS from MRSA affected quarters (357,000 cells/ml) in comparison to all quarters (114,000 cells/ml) (p<0.05). In BTM, MRSA was detected on 12 farms. In the environment, LA-MRSA was detected in dust, teat liners and automatic calf feeders. In samples from farm personnel, MRSA was detected on 4/7 farms.
Characterization of isolates: All MRSA isolates carried the mecA gene and belonged to CC398. Moreover, most iso- lates were identified as SCCmec-type V and spa-types t011 and t034. Results from NGS revealed additional genes that mediate resistance against aminoglycosides, macrolides, trimethoprim, tetracycline and lincosamides. Determination of virulence-associated genes in LA-MRSA isolates predicts low risk for human infections.
Potential risk factors: Improper milking hygiene procedures were observed on all farms with MRSA detection in milk (n=12). Two farms did not perform any udder cleaning and on one farm, one udder towel was used for all cows. Five MRSA-positive farms had no cluster disinfection and on one farm disinfection was only sporadically performed. Two farms did not do any post dipping and on three more farms post dipping was ineffective. Five MRSA affected farms kept both cattle and pigs at the same facility. However, MRSA was detected in only two pig barns and on one farm MRSA genotypes were different.
Conclusions: On 20 German dairy farms, the highest MRSA prevalence was detected in nasal swabs from young calves. Therefore, future MRSA monitoring programs should include samples from young stock. Improper milking hygiene as well as MRSA carrying humans and replacement heifers may enhance the spread of LA-MRSA CC398 within and between dairy herds. The role of pigs as a potential reservoir for LA-MRSA that may be transmitted to dairy cows needs to be further investigated.
Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
About
Affiliation of the authors at the time of publication
German Federal Institute for Risk Assessment, Berlin, Germany;
Robert Koch Institute, Berlin, Germany.
Comments (0)
Ask the author
0 comments