Short communication: Lack of intramammary niche recolonization during a sanitation program for the contagious mastitis pathogen Staphylococcus aureus genotype B.

In Switzerland, sanitation programs of dairy herds infected with the contagious mastitis pathogen Staphylococcus aureus genotype B (GTB) have been established for several years. In recent years, Streptococcus uberis and non-aureus staphylococci have emerged as the bacteria most frequently isolated from bovine milk samples. The latter cause subclinical mastitis, and some species are more persistent or pathogenic than others. The present study aimed to investigate the developments in the intramammary colonization spectrum of 5 dairy herds undergoing a sanitation program for Staph. aureus GTB. We collected single-quarter milk samples aseptically from all lactating cows at 3-mo intervals during the sanitation period; after classical bacteriological analysis, MALDI-TOF mass spectrometry was used to identify the isolates to the species level. Non-aureus staphylococci were found to be the bacterial group most frequently occurring on the selected farms, with Staphylococcus chromogenes and Staphylococcus xylosus being predominant. The present study demonstrated that GTB-infected cows treated with antibiotics lacked systematic recolonization with other bacteria during herd sanitation for the contagious Staph. aureus GTB.

Antimicrobial susceptibility patterns of blood culture isolates from foals in Switzerland.

INTRODUCTION: We report blood culture results of 43 foals admitted to an equine hospital for medical or surgical disorders and determine minimal inhibitory concentrations (MIC) of different antibiotics. Eleven foals had a positive blood culture result despite prior administration of antibiotics in 10 of these animals. MIC values above EUCAST and/or CLSI breakpoints were identified in coagulase-negative staphylococci, methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecium. Gram-negative isolates were less frequently identified and did not appear to exhibit increased MIC values. This study shows that bloodstream infections in foals in Switzerland are caused by diverse bacteria including Gram-positive bacteria which exhibit resistance to several classes of antibiotics.

INTRODUCTION: Nous rapportons les résultats d'hémoculture de 43 poulains admis dans un hôpital équin pour des affections médicales ou chirurgicales et déterminons les concentrations minimales inhibitrices (CMI) de différents antibiotiques. Le résultat de l'hémoculture a été positif pour onze poulains malgré l'administration préalable d'antibiotiques à 10 de ces animaux. Des valeurs de CMI supérieures aux seuils EUCAST et/ou CLSI ont été identifiées chez des staphylocoques coagulase négative, chez Staphylococcus aureus résistant à la méthicilline (MRSA) et chez Enterococcus faecium. Les isolats Gram négatifs étaient moins fréquemment identifiés et ne semblaient pas présenter de valeurs de CMI augmentées. Cette étude montre que les infections sanguines des poulains en Suisse sont causées par diverses bactéries, notamment des bactéries Gram positif, qui résistent à plusieurs classes d'antibiotiques.

Quarter- and cow-level risk factors for intramammary infection with coagulase-negative staphylococci species in Swiss dairy cows.

Bacteriological status, evaluation of udder symmetry, udder hygiene, and teat end scores of 92 dairy cows were assessed on 3 Swiss dairy farms in a longitudinal 1-yr study to determine risk factors for intramammary infection (IMI) with coagulase-negative staphylococci (CNS) species. Farm visits were performed monthly including sterile quarter milk sampling and udder evaluation of all lactating cows. Milk samples were evaluated for the presence of staphylococci using selective agar plates. Species identification was performed using MALDI-TOF mass spectrometry. Intramammary infection was defined as milk samples having ≥100 cfu per mL of milk according to culture results. Overall, 3,151 quarter samples were included in the statistical analysis. Staphylococcus chromogenes, Staphylococcus haemolyticus, Staphylococcus xylosus, and a Staphylococcus warneri-like species were the 4 most prevalent CNS species found. Hierarchical multivariable logistic regression models were built to evaluate risk factors for species-specific CNS IMI. Risk factors for Staph. chromogenes IMI were presence in herd B, the period from June 2014 to August 2014 and December 2014 to February 2015, and presence of udder edema. For Staph. haemolyticus, the relevant risk factor included coinfection with Staph. xylosus coinfection with other than the above-mentioned CNS species ("others") and the period from June 2014 to November 2014. Coinfection with Staph. haemolyticus and "others," the periods from June 2014 to August 2014 and December 2014 to February 2015, early phase of lactation (1-60 d in milk), and belonging to herd B were significantly associated with Staph. xylosus IMI. Mid and late lactation, coinfection with Staph. xylosus, and the period September 2014 to May 2015 were identified as significant risk factors for Staph. warneri-like IMI. For Staph. chromogenes, 60.6 and 26% of the variance was observed at the quarter and cow level, respectively, whereas for the other investigated species the highest variance was observed at the sample level. The predominant species within herds differed and was most pronounced for the Staph. warneri-like species.

Pathotyping and antibiotic resistance of porcine enterovirulent Escherichia coli strains from Switzerland (2014-2015).

INTRODUCTION: A total of 131 porcine E. coli were isolated in 2014 and 2015 from the gut of 115 pigs raised in Switzerland and suffering from diarrhea. The isolates were tested for antibiotic resistance, serotypes, virulence factors and genetic diversity. Serotypes were assigned by agglutination tests and virulence genes were identified by polymerase chain reaction (PCR). Antibiotic resistance profile was determined by the measurement of the MIC of 14 antibiotics and by the detection of the corresponding genes using microarray and PCR approaches. Genetic diversity was determined by repetitive palindromic PCR (rep- PCR) revealing a heterogenous population. Half of the E. coli isolates possessing virulence factors could not be assigned to any of the 19 serotypes tested, but contained toxins and adhesins similarly to the sero-typable E. coli isolates. The most prevalent E. coli serotypes found were K88ac (18%), O139:K82 (6%), O141:K85ac (5%), O108:K`V189` (5%), O119:K`V113` (3%) and O157:K`V17` (2%). The combination of toxins EAST-1, STb and LT-I and adhesin F4 characterizing ETEC was the most frequent. The shigatoxin Stx2e (STEC) and intimin Eae (EPEC) were also detected, but less frequently. Seventy percent of the isolates were resistant to at least one antibiotic and 29% were resistant to more than 3 antibiotics. Isolates exhibited resistance to tetracycline (50%) associated to resistance genes tet(A), tet(B) and tet(C), sulfamethoxazole (49%) [sul1, sul2 and sul3], trimethoprim (34%) [dfr], nalidixic acid (29%), ampicillin (26%) [blaTEM-1], gentamicin (17%) [aac(3) -IIc, aac(3) -IVa and aac(3) -VIa], chloramphenicol (17%) [catAI and catAIII], and ciprofloxacin (8%) [mutations in GyrA (S83L) and ParC (S80I)]. All isolates were susceptible to 3rd generation cephalosporins, carbapenems, colistin and tigecycline. Pathogenic E. coli isolates from pigs in Switzerland could frequently not be assigned to a known serotype even if they contained diarrhea-causing virulence factors. They also harbor resistance mechanisms conferring resistance to antibiotics which are commonly used in pig husbandry, except for colistin. A careful identification of the causative agent and antibiotic susceptibility testing is highly recommended for targeted therapy and prudent use of antibiotics.

INTRODUCTION: Dans la cadre de cette étude, on a isolé, durant les années 2014 et 2015, 131 souches d'E.coli provenant des intestins de porcs suisses souffrant de diarrhée. Ces souches ont été testées quant à leurs résistances aux antibiotiques; en outre on a déterminé leurs sérotypes, leurs facteurs de virulence et leur diversité génétique. L'attribution des isolats d'E.coli aux divers sérogroupes a été réalisée au moyen d'une séro-agglutination et les facteurs de virulence ont été déterminés par PCR. Les profils de résistance aux antibiotiques ont été déterminés par la mesure des concentrations inhibitrices minimales de 14 antibiotiques. Les gènes qui y étaient associés ont été identifiés par puces à ADN et PCR. La diversité génétique a été déterminée au moyen de PCR répétitives palindromiques (rep PCR). La moitié des isolats d'E.coli qui possédaient des facteurs de virulence n'ont pas pu être classés dans un des 19 sérotypes testés, bien qu'ils aient possédé les mêmes toxines et adhésines que les isolats qu'il a été possible de typiser. Les sérotypes les plus fréquemment trouvés étaient (18%), O139:K82 (6%), O141:K85ac (5%), O108:K`V189` (5%), O119:K`V113` (3%) et O157:K`V17` (2%). La combinaison des toxines EAST-1, STb et LT-I et de l'adhésine F4, qui est caractéristique pour les E.coli entérotoxiques (ETEC), a été le plus fréquemment trouvée. La shigatoxine Stx2e (STEC) et l'Intimin Eae (EPEC) étaient par contre plutôt rares. Les résultats des rep PCR montraient une population hétérogène. 70% des isolats présentaient une résistance face à au moins un antibiotique et 29% étaient résistants à plus de 3 antibiotiques. Les isolats montraient des résistances vis-à-vis de la tétracycline (50%) associée avec les gènes de résistance tet(A), tet(B) et tet(C), du sulfaméthoxazole (49%) [sul1, sul2 et sul3], du trimethoprime (34%) [dfr], de l'acide nalidixique (29%), de l'ampicilline (26%) [blaTEM-1], de la gentamicine (17%) [aac(3) -IIc, aac(3) -IVa et aac(3) -VIa], du chloramphenicol (17%) [catAI and catAIII] et de la ciprofloxacine (8%) [mutations dans GyrA (S83L) et ParC (S80I)]. Tous les isolats étaient sensibles aux céphalosporines de troisième génération, au carbapénèmes, à la colistine et à la tigecycline. Les E.coli pathogènes des porcs en Suisse n'ont souvent pas pu être attribués aux sérogroupes connus, bien qu'ils possèdent les facteurs de virulence causant la diarrhée. En outre on a découvert divers mécanismes de résistance contre des antibiotiques qui sont régulièrement utilisés dans la production porcine. En conséquence, une identification rigoureuse et soignée des germes responsables de maladie et un testage de la sensibilité avant traitement est de première importance.

Bacterial, fungal, parasitological and pathological analyses of abortions in small ruminants from 2012-2016.

INTRODUCTION: Abortion in small ruminants presents a clinical and economic problem with legal implications regarding animal health and zoonotic risk by some of the abortive pathogens. Several bacteria, fungi and parasites can cause abortion, but cost-orientated routine diagnostics only cover the most relevant epizootic agents. To cover a broad-range of common as well as underdiagnosed abortifacients, we studied 41 ovine and 36 caprine abortions by Stamp's modification of the Ziehl-Neelsen stain, culture for classical and opportunistic abortive agents, real-time PCR for C. burnetii, C. abortus, pathogenic Leptospira spp., Toxoplasma gondii and Neospora caninum. When the dam's serum was available detection of antibodies against B. melitensis, C. burnetii, C. abortus and Leptospira spp. was performed. In 37 cases sufficient placental tissue was available for pathological and histopathological examination. From the 77 cases 11 (14.3%) were positive by staining whereas real-time PCR detected C. burnetii and C. abortus in 49.3% and 32.5% of the cases. Antibodies against C. abortus and Leptospira spp. (33.3 and 26.7%) were detected. In 23.4% a bacterial culturable pathogen was isolated. Fungal abortion was confirmed in 1.3% of cases. A single abortive agent was identified in 44.2% of the cases and in 31.2% multiple possible abortifacients were present. Our study shows that the highest clarification rate can only be achieved by a combination of methods and evidences the role that multi-infections play as cause of abortion.

INTRODUCTION: Les avortements représentent un problème à la fois clinique et économique avec des conséquences en matière d'épizooties et un risque de zoonose pour certains agents. Diverses bactéries, champignons et parasites peuvent causer des avortements mais le diagnostic de routine, orienté sur les coûts, se concentre sur les principaux agents épizootiques. Afin d'avoir une vision large sur les agents d'avortements les plus fréquents et sur ceux qui sont sous-diagnostiqués, nous avons examinés 41 avortements de moutons et 36 de chèvres au moyen d'une coloration de Ziehl-Neelsen modifiée selon Stamp, de cultures ciblant les agents d'avortements classiques et opportunistes, d'une PCR en temps réel ciblant C. burnetii, C. abortus, les leptospires pathogènes, Toxoplasma gondii et Neospora caninum. Lorsque du sérum de la mère était disponible, nous avons procédé à une recherche d'anticorps contre B. melitensis, C. burnetii, C. abortus et Leptospira spp. Dans 37 cas, on disposait d'assez de tissu placentaire pour des examens pathologiques. Sur les 77 cas, 11 (14.3%) étaient positifs à la coloration alors que la PCR en temps réel démontrait la présence de C. burnetii et de C. abortus dans 49.3% respectivement 32.5% des cas. On a trouvé des anticorps contre C. abortus und Leptospira spp. dans 33.3% respectivement 26.7% des cas. Dans 23.4% des cas, on a pu mettre en évidence des pathogènes bactériens cultivables. Un avortement mycotique a été confirmé dans 1.3% des cas. Dans 44.2% des cas, un seul agent abortif était présent et dans 31.2% des cas, on trouvait plusieurs agents potentiels. Notre étude indique que le plus haut taux de diagnostic ne peut être atteint qu'en combinant diverses méthodes et montre le rôle possible de multi infections dans l'origine des avortements.

Short communication: Role of Streptococcus pluranimalium in Mediterranean buffaloes (Bubalus bubalis) with different udder health statuses.

The aims of the current study were to describe presence and clinical role over time of Streptococcus pluranimalium isolated in milk samples of Mediterranean buffalo (MB). Two hundred composite milk samples originating from 40 primiparous MB were collected at 10, 30, 60, 90, and 150d in milk (DIM) and from 20 pluriparous MB at 77 to 120 DIM. Milk samples were used for analysis of somatic cell counts, bacteriological cultures, and identification (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry). Nine of 200 (4.5%) samples of primiparous MB and 3 of 20 (15%) samples of pluriparous MB were positive for Strep. pluranimalium. The prevalence of the bacterium in primipari was 0% (0/40) at 10, 30, and 150 DIM, whereas it was 5 (2/40) and 17.5% (7/40) at 60 and 90 DIM, respectively. Eight primipari were positive only once, whereas 1 was positive at 2 different samplings. Mono-infection was not detected in any of the age categories or udder health status. Infections were transient in primipari. Clinical mastitis was observed in primipari once at 90 DIM, subclinical mastitis detected twice in the same animals at 60 and 90 DIM, and intramammary infections were diagnosed 1 and 5 times at 60 and 90 DIM in primipari, respectively, whereas 3 infections were diagnosed in pluripari. The clinical reflections demonstrate for the first time the presence of Strep. pluranimalium in MB and its association with different udder health status. Nevertheless, it cannot be excluded that the bacterium may simply follow a pattern of commensal or opportunistic behavior, taking advantage of a preexisting bacterial udder infection.

[Bacterial resistance in bacteria isolated from the nasal cavity of Swiss dairy calves]. / Resistenzen bei Bakterienisolaten aus der Nase von Aufzuchtkälbern in Milchviehbetrieben.

INTRODUCTION: Fifty-six E. coli, 37 P. multocida und 8 M. haemolytica were isolated from 157 nasal swabs taken from calves in 52 dairy herds. The antibiotic susceptibility of the organisms was determined by measurement of the minimal inhibitory concentrations. Of the 56 E. coli isolates, 55.3% exhibited resistance to tetracyclines, 55.3% to sulfonamides, 39.3% to beta-lactams, 30.3% to aminoglycosides, 8.9% to fluorochinolones and 3.5% to 3rd generation cephalosporins. The 3rd generation cephalosporin- resistant isolates contained the extended spectrum-beta-lactamase gene blaCTX-M-14 and came from 2 farms where the milk of cows under antimicrobial treatment was fed to the calves and mastitis was treated with cefquinome as first line therapy. Of the 37 P. multocida isolates, 48.6% exhibited resistance to tetracyclines, 16.2% to beta-lactams, and 5.4% each to macrolides, aminoglycosides and sulfonamides. The 8 M. haemolytica isolates showed no resistances against the tested antibiotics.

INTRODUCTION: Dans 52 exploitations laitières, 157 écouvillons ont été prélevés des fosses nasales de veaux d'élevage, desquels ont été isolés 56 Escherichia coli, 37 Pasteurella multocida et 8 Mannheimia haemolytica. Les profils de résistance de ces germes ont été déterminés par la mesure de la concentration minimale inhibitrice. Pour les E. coli, 55.3% des souches isolées montraient une résistance aux tétracyclines, 55.3% aux sulfamidés, 39.3% aux béta-lactamines, 30.3% aux aminoglycosides, 8.9% aux fluoroquinolones et 3.5% aux céphalosporines de 3ème génération. Les souches résistantes aux céphalosporines de 3ème génération présentaient un gène de béta-lactamase à spectre étendu blaCTX-M-14 et provenaient de deux exploitations dans lesquelles le lait de vaches sous traitement antibiotique était distribué aux veaux et où le cefquinome était utilisé comme antibiotique de premier recours pour le traitement des mammites. Pour P. multocida, 48.6% des couches étaient résistantes aux tétracyclines, 16.2% aux béta-lactamines et 5.4% chacun aux macrolides, aux aminoglycosides et aux sulfamidés. Les 8 isolats de M. haemolytica étaient sensibles à tous les antibiotiques testés.

Methicillin-resistant Staphylococcus aureus isolated from dogs and cats in Switzerland.

INTRODUCTION: Twenty-two methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from various infected locations in domestic cats and dogs between June 2008 and September 2014 were analyzed for their genotype, genetic fingerprint, virulence and antibiotic resistance profile. Eighteen strains belonged to the clonal complex (CC) 22 [ST22(MLST)-A(PFGE)-t032(spa)-IV(SCCmec) and ST22-A-t1214-IV], 2 strains to the livestock associated MRSA ST398-t011-IV and two were individual strains of ST5-t002-II and ST1-t001-IV. They contained virulence factors such as γ-hemolysins, ß-hemolysin converting phage genes, leukocidins and enterotoxins. Most widespread resistances were observed against ß-lactams, trimethoprim and fluoroquinolones, but single strains also exhibited resistance to macrolides, lincosamides, aminoglycosides, tetracycline, chloramphenicol and/or mupirocin. The predominant presence of CC22 MRSA strongly indicates clonal spread of a human associated lineage in Swiss companion animals. It is therefore of public health importance to maintain a low level of MRSA infections in animals to avoid uncontrolled dissemination of MRSA clones in humans and animals.

INTRODUCTION: Entre juin 2008 et septembre 2014, 220 souches de Staphylococcus aureus résistantes à la méthicilline (SARM) ont été isolées de divers foyers infectieux chez des chiens et des chats et leur génotype, leur virotype et leur profil de résistance aux antibiotiques ont été déterminés. Le complexe clonal (CC) 22 [ST22(MLST)-A(PFGE)-t032(spa)-IV(SCCmec) et ST22-A-t1214-IV] était le type de SARM principal, suivi par le CC398 (ST398-D-t011-IV) normalement associé aux animaux de rente ainsi que par quelques autres souche de SARM (ST5-C-t002-II, ST1-B-t001-IV). Les types de SARM de cette étude avaient un type de virulence relativement conservé, marqué par des gènes associés à la γ-hémolysine, des gènes d'entérotoxines, des gènes de virulence sur les phages convertissant la ß-hémolysin et des gènes de leucocidine. Les souches étaient en outre principalement résistantes au ß-lactame, au triméthoprime et aux fluoroquinolones, certaines d'entre elles présentant des résistances supplémentaires aux macrolides, aux lincosamides, aux aminoglycosides, aux tétracyclines, au chloramphénicol et/ou à la mupirocine. La fréquence des infections avec des SARM du complexe clonal CC22 indique clairement que ce clone associé à l'être humain peut se répandre facilement dans la population suisse d'animaux de compagnie. Pour réduire cette expansion de SARM chez les hommes et les animaux, il faut chercher à limiter le plus possible les infections dues aux SARM chez les animaux de compagnie.

Strain typing and antimicrobial susceptibility of methicillin-resistant coagulase-positive staphylococcal species in dogs and people associated with dogs in Thailand.

AIMS: This study was to investigate and to characterize methicillin-resistant coagulase-positive staphylococci (MRCoPS) harboring in dogs and people associated with dogs in Thailand. METHODS AND RESULTS: Staphylococci were collected from 100 dogs, 100 dog owners, 200 small animal veterinarians and 100 people without pet association. Species of MRCoPS were identified phenotypically and genotypically. Molecular characteristics were determined by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and SCCmec typing, and antimicrobial susceptibility was assayed by broth microdilution and by microarray analysis for resistance genes. Methicillin-resistant Staphylococcus pseudintermedius (MRSP), methicillin-resistant Staphylococcus schleiferi subsp. coagulans (MRSSc) and methicillin-resistant Staphylococcus aureus (MRSA) were isolated from dogs (45, 17 and 1%, respectively), veterinarians (8, 2 and 1·5%, respectively) and dog owners (3, 2 and 0%, respectively). Seventeen sequence types (STs) were identified among 83 MRSP isolates which specifically carried SCCmec V, II-III, ΨSCCmec57395 and three uncharacterized SCCmec types. MRSP ST 45, 68 and novel STs including 169, 178, 181 and 183 were shared among canine and human isolates. Most of MRSA ST398 and MRSSc carried SCCmec type V. The MRCoPS commonly displayed multiple resistances to tested antimicrobials and carried various resistance genes. CONCLUSION: Variety of MRCoPS, especially new MRSP clones, distributed in dogs and people in Thailand. SIGNIFICANCE AND IMPACT OF THE STUDY: The existence of MRCoPS circulating between dogs and humans in Thailand provides indirect evidence of interspecies transmission and represents a potential public health hazard.

Nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) among Swiss veterinary health care providers: detection of livestock- and healthcare-associated clones.

We screened a total of 340 veterinarians (including general practitioners, small animal practitioners, large animal practitioners, veterinarians working in different veterinary services or industry), and 29 veterinary assistants for nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus pseudintermedius (MRSP) at the 2012 Swiss veterinary annual meeting. MRSA isolates (n = 14) were detected in 3.8 % (95 % CI 2.1 - 6.3 %) of the participants whereas MRSP was not detected. Large animal practitioners were carriers of livestock-associated MRSA (LA-MRSA) ST398-t011-V (n = 2), ST398-t011-IV (n = 4), and ST398-t034-V (n = 1). On the other hand, participants working with small animals harbored human healthcare-associated MRSA (HCA-MRSA) which belonged to epidemic lineages ST225-t003-II (n = 2), ST225-t014-II (n = 1), ST5-t002-II (n = 2), ST5-t283-IV (n = 1), and ST88-t186-IV (n = 1). HCA-MRSA harbored virulence factors such as enterotoxins, ß-hemolysin converting phage and leukocidins. None of the MRSA isolates carried Panton-Valentine leukocidin (PVL). In addition to the methicillin resistance gene mecA, LA-MRSA ST398 isolates generally contained additional antibiotic resistance genes conferring resistance to tetracycline [tet(M) and tet(K)], trimethoprim [dfrK, dfrG], and the aminoglycosides gentamicin and kanamycin [aac(6')-Ie - aph(2')-Ia]. On the other hand, HCA-MRSA ST5 and ST225 mainly contained genes conferring resistance to the macrolide, lincosamide and streptogramin B antibiotics [erm(A)], to spectinomycin [ant(9)-Ia], amikacin and tobramycin [ant(4')-Ia], and to fluoroquinolones [amino acid substitutions in GrlA (S84L) and GyrA (S80F and S81P)]. MRSA carriage may represent an occupational risk and veterinarians should be aware of possible MRSA colonization and potential for developing infection or for transmitting these strains. Professional exposure to animals should be reported upon hospitalization and before medical intervention to allow for preventive measures. Infection prevention measures are also indicated in veterinary medicine to avoid MRSA transmission between humans and animals, and to limit the spread of MRSA both in the community, and to animal and human hospitals.

Multilocus sequence typing for characterization of Staphylococcus pseudintermedius.

Staphylococcus pseudintermedius is an opportunistic pathogen in dogs. Four housekeeping genes with allelic polymorphisms were identified and used to develop an expanded multilocus sequence typing (MLST) scheme. The new seven-locus technique shows S. pseudintermedius to have greater genetic diversity than previous methods and discriminates more isolates based upon host origin.

Antimicrobial susceptibility of gram-positive udder pathogens from bovine mastitis milk in Switzerland.

We evaluated the susceptibility of the gram-positive mastitis pathogens S. aureus, Str. uberis, Str. dysgalactiae, E. faecalis and L. garviae to antibiotics that are of epidemiological interest or are critically important for mastitis therapy and human medicine. Penicillin resistance was found to be most frequent in S. aureus, and nearly 5 % of the Str. uberis strains displayed a decreased susceptibility to this antibiotic. Resistance to aminoglycosides and macrolides was also detected in the strains tested. The detection of methicillin-resistant S. aureus (MRSA) and of a ciprofloxacin-resistant Str. dysgalactiae isolate corroborated the emergence of mastitis pathogens resistant to critically important antibiotics and underscores the importance of susceptibility testing prior to antibiotic therapy. The monitoring of antibiotic susceptibility patterns and antibiogram analyses are strongly recommended for targeted antimicrobial treatment and to avoid the unnecessary use of the latest generation of antibiotics.

Dans cette étude, on étudie la sensibilité des germes gram positifs causant des mammites, tels que S. aureus, Str. uberis, Str. dysgalactiae, E. faecalis und L. garviae, vis à vis d'une part d'antibiotiques à signification thérapeutique et, dautre part, vis à vis d'antibiotiques d'importance épidémiologique et d'antibiotiques de réserve en médecine humaine. On constate le plus souvent des résistances face à la pénicilline chez S. aureus mais environ 5 % des souches de Str. uberis présentaient également une sensibilité réduite à cet antibiotique. On a en outre constaté des résistances face aux aminoglycosides et aux macrolides. L'identification de S.aureus résistants à la méthicilline (MRSA) et d'un Str. dysgalactiae résistant à la ciprofloxacine démontre que les germes de mammites développent des résistances face aux antibiotiques de réserve importants ainsi que l'importance de la réalisation d'un antibiogramme avant un traitement antibiotique. Une surveillance de la situation de résistance et une interprétation des résultats des antibiogrammes sont indispensables pour effectuer un traitement antibactérien ciblé pour éviter l'utilisation inutile d'antibiotiques de nouvelle génération.

Characterization of third-generation cephalosporin-resistant Escherichia coli from slaughter calves and fattening pigs: A pilot study for monitoring antimicrobial resistance by whole genome sequencing in Switzerland.

INTRODUCTION: Whole genome sequencing (WGS) was introduced into Swiss antimicrobial resistance monitoring in 2022 as an additional method to phenotypic antimicrobial susceptibility testing by broth microdilution to characterize presumptive third-generation cephalosporin-resistant (3GC-R) Escherichia coli. Caecal samples from Swiss slaughter calves and fattening pigs, as well as beef and pork meat from Swiss retail taken in 2021, were analyzed for the presence of 3GC-R E. coli according to European harmonized protocols. In 2021, 3GC-R E. coli was detected in 23,8 % of slaughter calves, 5,9 % of fattening pigs, and 0 % of meat. Comparative analysis of the antimicrobial resistance results obtained by phenotypic measurement and those obtained by the detection of corresponding underlying molecular mechanisms by WGS showed very high agreement (99 %). Resistance to third-generation cephalosporins (3GCs) was mainly associated with the presence of blaCTX-M-15 in E. coli isolates from calves and blaCTX-M-1 in E. coli isolates from pigs and mutations in the ampC-promoter (g.-42 C>T) in E. coli isolates from both animal species. Moreover, WGS data were used for phylogenetic analysis based on multi locus sequence types (MLST) and core genome MLST(cgMLST) revealing that 3GC-R E. coli isolated from Swiss slaughter calves and fattening pigs were genetically diverse. In this study, it was shown that using WGS alone to monitor antimicrobial resistance could detect trends in known molecular antimicrobial resistance mechanisms while also providing other valuable information about the isolates, such as genetic relatedness. However, only by combining phenotypic susceptibility testing and WGS early detection of previously unknown resistance mechanisms will be possible.

INTRODUCTION: Le séquençage du génome entier (Whole Genome Sequencing, WGS) a été introduit dans la surveillance suisse de la résistance aux antibiotiques en 2022 en tant que méthode supplémentaire aux tests phénotypiques de sensibilité aux antibiotiques pour caractériser les Escherichia coli résistants aux céphalosporines de troisième génération (3GC-R). Des échantillons de cæcum pris en 2021 à l'abattoir de veaux et de porcs suisses, ainsi que de viande de bœuf et de porc provenant de détaillants suisses ont été analysés pour détecter la présence d'E. coli 3GC-R conformément aux protocoles européens harmonisés. En 2021, les E. coli 3GC-R ont été détectés dans 23,8 % des veaux d'abattage, 5,9 % des porcs d'engraissement et 0 % dans la viande. Les résultats de résistance aux antibiotiques obtenus par mesure phénotypique et ceux obtenus par la détection des mécanismes moléculaires sous-jacents concordaient à 99 %. La résistance aux céphalosporines de troisième génération était principalement associée à la pré-sence de blaCTX-M-15 dans les isolats d'E. coli provenant de veaux et de blaCTX-M-1 dans les isolats d'E. coli provenant de porcs et à des mutations dans le promoteur ampC (g.-42 C>T) dans les isolats d'E. coli provenant des deux espèces animales. Les données WGS ont également été utilisées pour une analyse phylogénétique basée sur les types de séquences multilocus (MLST) et MLST du génome de base (cgMLST) révélant que les E. coli 3GC-R isolés des veaux et des porcs suisses étaient génétiquement divers. Dans cette étude, il a été démontré que l'utilisation du WGS seul pour surveiller la résistance aux antibiotiques pouvait détecter des tendances dans les mécanismes moléculaires connus de la résistance aux antibiotiques tout en fournissant d'autres informations précieuses sur les isolats, comme la parenté génétique. Cependant, ce n'est qu'en combinant les tests de sensibilité phénotypique avec le WGS que la détection pré-coce de mécanismes de résistance inconnus sera possible.

Antimicrobial susceptibility of canine Clostridium perfringens strains from Switzerland.

Fifty Clostridium perfringens strains were isolated from individual dogs with acute diarrhoea that were not given antibiotics. Toxin types and minimal inhibitory concentrations of 15 antibiotics were determined for each of them. All strains harboured the alpha-toxin gene, 12 of them had both the alpha- and entero-toxin gene and 5 had both the alpha- and beta2-toxin gene. Eighteen percent of the isolates showed resistance to tetracycline and 54 % showed decreased susceptibility to metronidazole which is one of the most frequently used antibiotics in the treatment of canine diarrhoea. Apart from that, all isolates were susceptible to the remaining antibiotics tested. These findings lead to the conclusion that despite a general susceptibility to antibiotics in C. perfringens, resistance is developing in isolates from dogs. Therefore, careful identification of the pathogenic agent and antibiotic susceptibility testing should be performed prior to therapy in order to minimise further selection of antibiotic resistance.

Prevalence and characterization of -methicillin-resistant Macrococcus spp. in food producing animals and meat in Switzerland in 2019.

INTRODUCTION: The prevalence of methicillin-resistant Macrococcus spp. in calves and pigs at slaughterhouses and in retail beef and pork meat was determined using samples taken in 2019 within the framework of the national monitoring of methicillin-resistant Staphylococcus aureus in food producing animals in Switzerland. The isolates were submitted to antimicrobial susceptibility testing of 19 antibiotics and to molecular techniques (e.g. PCR, microarray, WGS) for the identification of resistance genes, elements containing the methicillin resistance genes mec and sequence type (ST). Methicillin-resistant Macrococcus spp. (M. caseolyticus (n=38), M. bohemicus (n=4) and Macrococcus spp. (n=2)) were isolated in 40 of 299 nasal swabs from calves representing a prevalence of 13,38 % (95 % CI, 9,98 % - 17,70 %), and in four of 303 nasal swabs from pigs [1,32 % (95 % CI, 0,36 % - 3,35 %)]. One of 311 samples of Swiss pork meat contained a Macrococcus sp. [0,32 % (95 % CI, 0,01 % - 1,78 %)], and four of 309 beef meat samples (260 domestic and 49 imported) contained M. caseolyticus [1,29 % (95 % CI, 0,35 % - 3,28 %)]. The M. caseolyticus strains belonged to diverse STs, with ST21 being the most common in both pigs and calves. The mecD gene was located on Macrococcus resistance island mecD (McRImecD) in 42 strains and on staphylococcal cassette chromosome mec (SCCmecD) in three strains, while mecB was found on plasmids in four strains. In addition to resistance to ß-lactams, the strains also exhibited resistance to tetracycline (n=17; tet(L), tet(K), tet(M)), streptomycin (n=13; str, ant(6)-Ia, rpsL mutation [K56R in ribosomal protein S12]), kanamycin (n=10; aac(6')-Ie - aph(2'')-Ia, aph(2')-Ib, aph(2')-Ic, ant(4')-Ia), clindamycin (n=9; erm(B), erm(45)), erythromycin (n=9; erm(B), msr(G), erm(45)), fusidic acid (n=9; fusC) and gentamicin (n=1; aac(6')-Ie - aph(2'')-Ia). This study represents the first national prevalence study of methicillin-resistant Macrococcus spp. in pigs, calves, pork and beef meat in Switzerland and revealed a reservoir of genetically diverse strains carrying several resistance traits.

INTRODUCTION: La prévalence des macrococques résistants à la méthicilline chez les veaux et les porcs à l'abattoir et dans la viande de bœuf et de porc au détail a été déterminée à partir d'échantillons prélevés en 2019 dans le cadre du monitoring national des Staphylococcus aureus résistants à la méthicilline chez les animaux de rente en Suisse. Les isolats ont été soumis à des tests de sensibilité à 19 antibiotiques et à des techniques moléculaires (par exemple PCR, microarray, WGS) pour l'identification des gènes de résistance, des éléments contenant les gènes mec responsible de la résistance à la méthicilline, ainsi que du type de séquence (ST). Des macocoques résistants à la méthicilline (M. caseolyticus (n=38), M. bohemicus (n=4) et Macrococcus spp. (n=2)) ont été isolés dans 40 des 299 écouvillons nasaux de veaux, ce qui représente une prévalence de 13,38 % (IC 95 %, 9,98 % ­ 17,70 %), et dans quatre des 303 écouvillons nasaux de porcs [1,32 % (IC 95 %, 0,36 % ­ 3,35 %)]. Un des 311 échantillons de viande de porc suisse contenait un Macrococcus sp. [0,32 % (IC 95 %, 0,01 % ­ 1,78 %)], et quatre des 309 échantillons de viande de bœuf (260 domestiques et 49 importés) contenaient M. caseolyticus [1,29 % (IC 95 %, 0,35 % ­ 3,28 %)]. Les souches de M. caseolyticus appartenaient à divers ST, le ST21 étant le plus fréquent chez les porcs et les veaux. Le gène mecD a été localisé sur des éléments du chromosome McRImecD dans 42 souches et SCCmecD dans trois souches, tandis que le gène mecB se trouvait sur des plasmides dans quatre souches. En plus de la résistance aux ß-lactamines, les souches étaient également résistantes à la tétracycline (n=17 ; tet(L), tet(K), tet(M)), à la streptomycine (n=13 ; str, ant(6)-Ia, mutation rpsL [K56R dans la protéine ribosomale S12]), à la kanamycine (n=10 ; aac(6')-Ie ­ aph(2'')-Ia, aph(2')-Ib, aph(2')-Ic, ant(4')-Ia), clindamycine (n=9 ; erm(B), erm(45)), érythromycine (n=9 ; erm(B), msr(G), erm(45)), acide fusidique (n=9 ; fusC) et gentamicine (n=1 ; aac(6')-Ie ­ aph(2'')-Ia). Cette étude est la première à déterminer prévalence des Macrococcus spp. résistants à la méthicilline chez les porcs, les veaux, la viande de porc et de bœuf en Suisse et a révélé un réservoir de souches génétiquement diverses et portant plusieurs traits de résistance.

Distribution, genetic heterogeneity, and antimicrobial susceptibility of Brachyspira pilosicoli in Swiss pig herds.

Brachyspira (B.) pilosicoli is a bacterium causing porcine intestinal spirochaetosis, a disease characterized by diarrhoea and depressed growth rates especially in nursery and fattening pigs. Knowledge of the epidemiology and antimicrobial susceptibility of this pathogen is limited. Therefore, the aim of this study was to analyse the distribution, genetic heterogeneity, and antimicrobial susceptibility of B. pilosicoli field isolates from Swiss pig farms. Faecal swabs of 693 animals originating from 156 herds were analysed for the presence of Brachyspira spp. using culture and polymerase chain reaction identification. Further characterisation was performed using multilocus sequence typing (MLST) and broth dilution antimicrobial susceptibility testing. With 52.6% positive herds, B. pilosicoli could be frequently isolated from herds with animals suffering from diarrhoea. In herds with animals without clinical signs of diarrhoea, detection was significantly less frequent with only 10.5% positive herds (p 0.001). Among 80 isolates used for typing, genetic heterogeneity was observed with 44 different sequence types (ST) which often differed from herd to herd. No predominant ST was observed. More than 73.0% of the 41 B. pilosicoli isolates analysed, showed minimal inhibitory concentration values above the wild type cut-off values for lincomycin, tylvalosin and/ or tylosin. For tiamulin, valnemulin and doxycycline, this was the case in 48.8%, 43.9% and 36.6%, respectively. In conclusion, a diverse population of B. pilosicoli exhibited decreased susceptibility to antimicrobials used against Brachyspira infections. Monitoring of resistance in Brachyspira spp. is highly recommended to support targeted use of antimicrobials in pigs.

Antimicrobial susceptibility in E. coli and Pasteurellaceae at the beginning and at the end of the fattening process in veal calves: Comparing 'outdoor veal calf' and conventional operations.

Animal husbandry requires practical measures to limit antimicrobial resistance (AMR). Therefore, a novel management and housing concept for veal calf fattening was implemented on 19 intervention farms (IF) and evaluated regarding its effects on AMR in Escherichia (E.) coli, Pasteurella (P.) multocida and Mannheimia (M.) haemolytica in comparison with 19 conventional control farms (CF). Treatment intensity (-80%) and mortality (-50%) were significantly lower in IF than in CF, however, production parameters did not differ significantly between groups. Rectal and nasopharyngeal swabs were taken at the beginning and the end of the fattening period. Susceptibility testing by determination of the minimum inhibitory concentration was performed on 5420 isolates. The presence of AMR was described as prevalence of resistant isolates (%), by calculating the Antimicrobial Resistance Index (ARI: number of resistance of one isolate to single drugs/total number of drugs tested), by the occurrence of pansusceptible isolates (susceptible to all tested drugs, ARI=0), and by calculating the prevalence of multidrug (≥3) resistant isolates (MDR). Before slaughter, odds for carrying pansusceptible E. coli were higher in IF than in CF (+65%, p=0.022), whereas ARI was lower (-16%, p=0.003), and MDR isolates were less prevalent (-65%, p=0.001). For P. multocida, odds for carrying pansusceptible isolates were higher in IF before slaughter compared to CF (+990%, p=0.009). No differences between IF and CF were seen regarding the prevalence of pansuceptible M. haemolytica. These findings indicate that easy-to-implement measures to improve calf management can lead to a limitation of AMR in Swiss veal fattening farms.

Prevalence and whole genome-based phylogenetic, virulence and antibiotic -resistance characteristics of nasal -Staphylococcus aureus in healthy Swiss horses.

INTRODUCTION: A total of 100 nasal swabs were collected from healthy horses in Switzerland between January 2020 and August 2020. The samples were taken from horses at 40 different stables in 12 different cantons and screened for both methicillin-resistant (MRSA) and methicillin-susceptible S. aureus (MSSA) using selective agar plates. S. aureus were tested for antibiotic susceptibility by measurement of the minimal inhibitory concentration (MIC) and for virulence factors, antibiotic resistance genes and phylogenetic characteristics using whole genome sequence analysis. Ten horses were found to be positive (10 %, CI: 95 %, 0,0552 - 0,1744) for S. aureus, and four of them harboured MRSA (4 %, CI: 95 %, CI: 1,5 % - 9 %). The MRSA were detected in horses from three different stables in the same region of one canton and MSSA were detected in horses from five different cantons. All the MRSA isolates were genetically related (ST398-t011-IVa), while the MSSA were diverse (ST1-t127/t398/t1508, ST816-t1294, ST133-t1403, ST30-t012). MRSA showed resistance to penicillin (blaZ), cefoxitin (mecA), trimethoprim (dfrK), gentamicin, kanamycin (aac(6')-Ie - aph(2'')-Ia), and tetracycline (tet(M)). MSSA were resistant to either none or one of the antibiotics tested like penicillin (blaZ) and erythromycin (erm(T)). Virulence genes were more abundant in MSSA than in MRSA. This study provides first insight into the prevalence and type of S. aureus in healthy Swiss horses and reveals a source of strains, which may cause infections in both horses and humans.

INTRODUCTION: Au total, 100 écouvillons nasaux ont été prélevés sur des chevaux sains en Suisse entre janvier 2020 et août 2020. Les échantillons ont été prélevés sur des chevaux de 40 écuries différentes dans 12 cantons différents et ont été soumis à un dépistage de S. aureus résistant à la méthicilline (MRSA) et de S. aureus sensible à la méthicilline (MSSA) à l'aide de plaques de gélose sélectives. Les S. aureus ont été testés pour leur sensibilité aux antibiotiques en mesurant la concentration minimale inhibitrice (CMI) et pour les facteurs de virulence, les gènes de résistance aux antibiotiques et les caractéristiques phylogénétiques en analysant la séquence du génome entier. Dix chevaux se sont révélés positifs (10 %, IC: 95 %, 0,0552 ­ 0,1744) pour S. aureus, et quatre d'entre eux étaient porteurs de MRSA (4 %, IC: 95 %, IC: 1,5 % ­ 9 %). Les MRSA ont été détectés chez des chevaux provenant de trois écuries différentes de la même région d'un canton et les MSSA ont été détectés chez des chevaux provenant de cinq cantons différents. Tous les isolats de MRSA étaient génétiquement apparentés (ST398-t011-IVa), tandis que les MSSA étaient divers (ST1-t127/t398/t1508, ST816-t1294, ST133-t1403, ST30-t012). Les MRSA étaient résistants à la pénicilline (blaZ), à la céfoxitine (mecA), au triméthoprime (dfrK), à la gentamicine, à la kanamycine (aac(6')-Ie ­ aph(2")-Ia) et à la tétracycline (tet(M)). Les MSSA étaient résistants à aucun ou à un des antibiotiques testés soit à la pénicilline (blaZ) ou à l'érythromycine (erm(T)). Les gènes de virulence étaient plus abondants chez les MSSA que chez les MRSA. Cette étude donne, pour la première fois, un aperçu de la prévalence et du type de S. aureus chez les chevaux suisses en bonne santé et révèle la présence de souches susceptibles de provoquer des infections chez les chevaux et les humains.

Repression of common bull sperm flora and in vitro impairment of sperm motility with Pseudomonas aeruginosa introduced by contaminated lubricant.

Semen collected from clinically healthy bulls at an artificial insemination centre was examined for bacterial diversity. While bacteria that are normally present in the common flora of bovine semen were absent, such as Mycoplasma sp., Proteus sp. and Corynebacterium sp., all semen samples contained an unusually high number of Pseudomonas aeruginosa strains. Analysis via pulsed field gel electrophoresis demonstrated that one particular P. aeruginosa strain, present in a sealed bottle of lubricant, was widespread in bull semen. This strain was shown to secrete substances that inhibited both the growth of bacteria constituting the normal bull sperm flora and the motility of spermatozoa in vitro. This study demonstrated that commercially available lubricants might contain bacteria that can spread amongst breeding bulls and affect the quality of semen. Bacteriological controls and species' identification are necessary at several production levels, including lubricants and extenders, to ensure high semen quality and avoid the spread of pathogens.

Bacterial infections in horses: a retrospective study at the University Equine Clinic of Bern.

Bacterial infections present a major challenge in equine medicine. Therapy should be based on bacteriological diagnosis to successfully minimize the increasing number of infections caused by multidrug-resistant bacteria. The present study is a retrospective analysis of bacteriological results from purulent infections in horses admitted at the University Equine Clinic of Bern from 2004 to 2008. From 378 samples analyzed, 557 isolates were identified, of which Staphylococcus aureus, Streptococcus equi subsp. zooepidemicus and coliforms were the most common. Special attention was paid to infections with methicillin-resistant S. aureus (MRSA) ST398 and a non-MRSA, multidrug-resistant S. aureus clone ST1 (BERN100). Screening of newly-admitted horses showed that 2.2 % were carriers of MRSA. Consequent hygiene measures taken at the Clinic helped to overcome a MRSA outbreak and decrease the number of MRSA infections.