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Objectives Plasmid-mediated colistin resistance can be transferred from animals to humans. We investigated the prevalence of carriage of mcr-mediated colistin-resistant Escherichia coli and Klebsiella pneumoniae (ColR-E/K) in veterinary healthcare workers and in the general population in the Netherlands. Methods Two cross-sectional population studies were performed: one among veterinary healthcare workers and one in the general population. Participants sent in a faecal sample and filled in a questionnaire. Samples were analysed using selective enrichment and culture. Mobile colistin resistance genes (mcr) were detected by PCR and ColR-E/K were sequenced using Illumina and Nanopore technologies. Results The prevalence of mcr-mediated ColR-E/K was 0.2% (1/482, 95% CI 0.04%–1.17%) among veterinary personnel and 0.8% (5/660, 95% CI 0.3%–1.8%) in the population sample. mcr-1 was found in E. coli from four persons, mcr-8 in K. pneumoniae from one person and another person carried both mcr-1 and mcr-8 in a K. pneumoniae isolate. mcr-1 was found on different plasmid types (IncX4, IncI1 and IncI2), while mcr-8 was found on IncF plasmids only. Conclusions mcr-mediated ColR-E/K resistance was uncommon in both populations. Professional contact with animals does not increase the chance of carriage of these bacteria in the Netherlands at present. mcr-8 was found for the first time in the Netherlands. Surveillance of colistin resistance and its underlying mechanisms in humans, livestock and food is important in order to identify emerging trends in time.

Bepaalde type bacteriën zijn resistent tegen antibiotica, zoals ESBLproducerende bacteriën. ESBL’s komen vaker voor bij dierenartsen en assistenten van dierenartsen dan bij mensen die niet met dieren werken. Het is aannemelijk dat dierenartsen en hun assistenten deze bacteriën bij zich dragen door het contact met dieren tijdens hun werk. Dit blijkt uit onderzoek van het RIVM. Veel deelnemers uit deze zorgsector hadden contact met verschillende soorten dieren, zowel huisdieren als vee. Van hen had 69 procent alleen contact met huisdieren. Het is daardoor niet mogelijk om aan te wijzen welk specifiek dier de bron van de resistente bacterie was. Het RIVM heeft onderzocht of drie soorten (antibioticaresistente) bacteriën in de ontlasting van de dierenartsen en dierenartsassistenten zaten. Dat waren ESBL-producerende bacteriën, bacteriën die resistent zijn tegen het ‘laatste redmiddel’ antibioticum colistine, en Clostridioides difficile (C. diff). Voor deze drie bacteriën zijn er namelijk aanwijzingen dat contact met dieren een kans geeft om ermee besmet te raken. Er deden 482 mensen mee aan het onderzoek. Colistineresistente bacteriën en C. diff kwamen even vaak voor bij dierenartsen en hun assistenten als bij de Nederlandse bevolking. Er zijn daarom geen aanwijzingen dat zij door hun werk een grotere kans hebben om deze twee soort bacteriën bij zich te dragen. Antibioticaresistente bacteriën kunnen in de darmen zitten van gezonde personen of dieren zonder dat zij daar last van hebben. Maar ze kunnen ook infecties veroorzaken. Infecties door deze bacteriën zijn moeilijker te behandelen met antibiotica. De bacteriën worden onder andere via de ontlasting van dieren verspreid. Een goede hygiëne is dan ook belangrijk om besmetting te voorkomen.

Tegen bepaalde type bacteriën werken antibiotica niet meer. Ze zijn daar resistent tegen geworden. Voorbeelden zijn colistine-resistente bacteriën. Deze bacteriën kunnen in de ontlasting van mensen, vee, en huisdieren zitten en in vlees. Het RIVM heeft voor het eerst onderzocht hoe vaak deze resistente bacteriën voorkomen bij de Nederlandse bevolking. Van 661 mensen is de ontlasting onderzocht. Colistineresistente bacteriën kwamen bij 36 mensen voor. De gegevens zijn als controle gebruikt voor de AREND-studie. Daarin is onder andere onderzocht of colistine-resistente bacteriën even vaak bij dierenartsen en hun assistenten voorkomen dan bij de bevolking. Dat blijkt het geval te zijn. Antibioticaresistente bacteriën kunnen in de darmen zitten van gezonde personen of dieren zonder dat zij daar last van hebben. Maar ze kunnen ook infecties veroorzaken. Infecties door deze bacteriën zijn moeilijker te behandelen met antibiotica. De bacteriën worden onder andere via de ontlasting of via besmet voedsel verspreid. Een goede hygiëne is dan ook belangrijk om besmetting te voorkomen.

In dit onderzoek is gekeken of de huidige monitoring van carbapenemase-producerende bacteriën (CPE) voldoende is om betrouwbare uitspraken te kunnen doen over het vóórkomen van deze bacteriën in dieren en/of dierlijke producten. De conclusie van dit rapport is dat méér en gerichter monsters van dieren en dierlijke producten genomen zouden moeten worden om lage prevalenties (vóórkomen) van CPE te kunnen monitoren. Daarmee wordt tevens de kans verhoogd besmettingen met CPE te ontdekken, voordat het verspreid is naar meerdere bedrijven, dieren en/of (dierlijke) producten. Het gaat om antibioticaresistente bacteriën die resistent zijn tegen het soms nog laatste redmiddel bij infecties, carbapenem antibiotica. Deze bacteriën worden gezien als bedreiging voor de volksgezondheid. Gelukkig komen deze nog niet zo vaak bij mensen in Nederland voor. Als dit type bacteriën in ziekenhuizen wordt aangetroffen, worden maatregelen getroffen om ervoor te zorgen dat ze zich niet verder kunnen verspreiden naar risicogroepen. Hoewel CPE tot nu toe in Nederland nog niet in dieren en/of dierlijke producten zijn aangetroffen, kunnen ook dieren en/of dierlijke producten een rol spelen bij de verspreiding ervan naar de mens. CPE zijn in het buitenland al wel incidenteel gevonden bij dieren. In de Nederlandse veestapel, onder gezelschapsdieren en in (dierlijke) producten vindt op dit moment een monitoring plaats naar CPE. Het is echter onzeker of deze monitoring voldoende is om veranderingen in het vóórkomen van CPE te bepalen en om CPE te vinden, op het moment dat deze nog niet verspreid zijn naar meerdere bedrijven, dieren en/of (dierlijke) producten. Daarom heeft het ministerie van VWS het RIVM gevraagd voorliggend onderzoek te doen. Het brengt de huidige monitoring van CPE in de Nederlandse veestapel, gezelschapsdieren en dierlijke producten gedetailleerd in kaart, geeft een overzicht van de betrouwbaarheid van deze metingen en inventariseert mogelijke verbeteringen. Uit het onderzoek blijkt dat de aantallen monsters die van dieren en producten genomen worden te klein zijn om betrouwbare uitspraken te doen over de afwezigheid van CPE in de veestapel en om veranderingen bij een lage prevalentie te kunnen waarnemen. Daarom wordt aanbevolen om in de monitoring meer monsters te onderzoeken. Ook is het zinvol om te analyseren waar de grootste risico's voor introductie van CPE in dieren en/of dierlijke producten liggen, zodat de aanvullende metingen zo gericht mogelijk kunnen worden uitgevoerd. Een eerste verkennende risico inventarisatie laat zien dat import van dieren en/of dierlijke producten uit gebieden waar CPE voorkomt, een mogelijk risico is voor invoer van CPE naar Nederland. Productiedieren kunnen ook besmet worden door overdracht vanuit bedrijven hoger in de productieketen, waar op dit moment geen monitoring plaatsvindt. Daarnaast kan er ook overdracht plaats vinden via besmette mensen. Door méér en gerichter monsters van dieren en (dierlijke) producten te nemen kan de afwezigheid van CPE met een betere betrouwbaarheid worden bepaald. Daarmee wordt tevens de kans verhoogd besmettingen met CPE te ontdekken, voordat het verspreid is naar meerdere bedrijven, dieren en/of (dierlijke) producten.

Dieren kunnen verwekkers van ziekten bij zich dragen die op mensen kunnen worden overgebracht (zoönosen). In 2016 hebben het RIVM en de NVWA onderzocht of melkgeiten en melkschapen zulke ziekteverwekkers bij zich dragen; soms is dat ook bij veehouders, gezinsleden en medewerkers gedaan. Deze ziekteverwekkers veroorzaken meestal diarree maar soms kunnen de infecties ook ernstiger verlopen. Uit het onderzoek blijkt dat een paar ziekteverwekkers vaak op melkgeiten- en melkschapenbedrijven voorkomen. De gevonden bacteriën zitten in de darmen van de dieren en komen zo in de mest terecht. Een kleine hoeveelheid mest kan rauw te drinken melk of rauwmelkse kaas al besmetten. Daarnaast kunnen bezoekers van deze bedrijven besmet raken als zij contact hebben met de dieren of hun omgeving. Een besmetting kan worden voorkomen door alle melk gepasteuriseerd te consumeren of te verwerken. Bezoekers kunnen de kans op ziekte verkleinen door hun handen te wassen als ze in contact zijn geweest met de dieren of hun omgeving. Vooral de bacteriën STEC en Campylobacter zijn in hoge mate aangetroffen. STEC kwam op vrijwel alle onderzochte bedrijven voor. Campylobacter is aangetoond op 33 procent van de geiten- en op 95,8 procent van de schapenbedrijven. Bij de veehouders en gezinsleden zijn deze bacteriën veel minder gevonden. Listeria kwam in mindere mate voor? op 8,8 procent van de geiten- en 16,7 procent van de schapenbedrijven, en niet bij de mensen. Het is wel een relevante ziekteverwekker omdat rauwmelkse zachte kaas hiervoor de belangrijkste infectiebron voor mensen is. Salmonella werd niet gevonden op melkgeitenbedrijven, maar wel op 12,5 procent van de melkschapenbedrijven. Op de meeste bedrijven werd alleen een type Salmonella gevonden dat niet overgedragen wordt op de mens. ESBL-producerende bacteriën, die ongevoelig zijn voor veel antibiotica, werden aangetoond op 1,7 procent van de geitenbedrijven en 4,2 procent van de schapenbedrijven. Daarnaast werd hij bij 6,8 procent van de mensen aangetroffen. Dit percentage is niet hoger dan bij de algemene bevolking.

Fifteen percent of all methicillin-resistant Staphylococcus aureus (MRSA) clonal complex 398 (CC398) human carriers detected in The Netherlands had not been in direct contact with pigs or veal calves. To ensure low MRSA prevalence, it is important to investigate the likely origin of this MRSA of unknown origin (MUO). Recently, it was shown that CC398 strains originating from humans and animals differ in the presence of specific mobile genetic elements (MGEs). We hypothesized that determining these specific MGEs in MUO isolates and comparing them with a set of CC398 isolates of various known origin might provide clues to their origin. MUO CC398 isolates were compared to MRSA CC398 isolates obtained from humans with known risk factors, a MRSA CC398 outbreak isolate, livestock associated (LA) MRSA CC398 isolates from pigs, horses, chickens, and veal calves, and five methicillin-susceptible Staphylococcus aureus (MSSA) CC398 isolates of known human origin. All strains were spa typed, and the presence or absence of, scn , chp , φ3 int , φ6 int , φ7 int , rep7 , rep27 , and cadDX was determined by PCRs. The MRSA CC398 in humans, MUO, or MRSA of known origin (MKO) resembled MRSA CC398 as found in pigs and not MSSA CC398 as found in humans. The distinct human MSSA CC398 spa type, t571, was not present among our MRSA CC398 strains; MRSA CC398 was tetracycline resistant and carried no φ3 bacteriophage with scn and chp . We showed by simple PCR means that human MUO CC398 carriers carried MRSA from livestock origin, suggestive of indirect transmission. Although the exact transmission route remains unknown, direct human-to-human transmission remains a possibility as well.

Objectives: The aim of this study was to determine the phenotypic and genotypic resistance profiles of methicillin-resistant Staphylococcus pseudintermedius (MRSP) and to examine the clonal distribution in Europe and North America. Methods: A total of 103 MRSP isolates from dogs isolated from several countries in Europe, the USA and Canada were characterized. Isolates were identified by PCR-restriction fragment length polymorphism (RFLP), antimicrobial susceptibility was determined by broth dilution or gradient diffusion, and antimicrobial resistance genes were detected using a microarray. Genetic diversity was assessed by multilocus sequence typing (MLST), PFGE and spa typing. Staphylococcal cassette chromosome mec (SCCmec) elements were characterized by multiplex PCR. Results: Thirteen different sequence types (STs), 18 PFGE types and 8 spa types were detected. The hybrid SCCmec element II-III described in a MRSP isolate was present in 75 (72.8%) isolates. The remaining isolates either had SCCmec type III (n=2), IV (n=6), V (n=14) or VII-241 (n=4) or were non-typeable (n=2). The most common genotypes were ST71(MLST)-J(PFGE)-t02(spa)-II-III(SCCmec) (56.3%) and ST68-C-t06-V (12.6%). In addition to mecA-mediated beta-lactam resistance, isolates showed resistance to trimethoprim [dfr(G)] (90.3%), gentamicin/kanamycin [aac(6')-Ie-aph(2')-Ia] (88.3%), kanamycin [aph(3')-III] (90.3%), streptomycin [ant(6')-Ia] (90.3%), streptothricin (sat4) (90.3%), macrolides and/or lincosamides [erm(B), lnu(A)] (89.3%), fluoroquinolones (87.4%), tetracycline [tet(M) and/or tet(K)] (69.9%), chloramphenicol (cat(pC221)) (57.3%) and rifampicin (1.9%). Conclusions: Two major clonal MRSP lineages have disseminated in Europe (ST71-J-t02-II-III) and North America (ST68-C-t06-V). Regardless of their geographical or clonal origin, the isolates displayed resistance to the major classes of antibiotics used in veterinary medicine and thus infections caused by MRSP isolates represent a serious therapeutic challenge.

Mensen kunnen op verschillende manieren blootgesteld worden aan bacteriën. Dit kunnen ook bacteriën zijn die resistent zijn tegen antibiotica, zoals de ESBL-producerende E. coli-bacteriën. Een van de mogelijke blootstellingsbronnen hiervan is vlees. Het RIVM heeft berekend in welke mate verschillende vleessoorten bijdragen aan de blootstelling van de mens aan ESBL-producerende bacteriën. Volgens deze schattingen is rundvlees een veel belangrijkere bron dan kippenvlees. Vlees van varken, kalf of schaap is minder relevant voor de totale blootstelling door het eten van vlees. Van de onderzochte vleessoorten is rundvlees verantwoordelijk voor circa 78 procent van de totale blootstelling via het eten van vlees. Dat komt vooral doordat sommige rundvleesproducten rauw worden gegeten, zoals filet americain. Op rauw kippenvlees komen de meeste ESBL-producerende bacteriën voor. Doordat het meestal goed wordt verhit voordat het wordt gegeten, is de blootstelling via kippenvlees veel lager (18 procent). Mensen kunnen wel door rauw kippenvlees besmet raken via kruisbesmetting in de keuken, bijvoorbeeld door kip en groente met hetzelfde mes of op dezelfde snijplank te snijden. In de berekeningen is rekening gehouden met de invloed van diverse factoren die de aanwezigheid van bacteriën op vlees beïnvloeden: soorten voorbewerking (verhitten, zouten, drogen/fermenteren), bewaarcondities (kamertemperatuur, koelkast, vriezer), en de bereiding in de keuken (rauw, goed doorbakken, half doorbakken, de mate van kruisbesmetting et cetera). Er zijn geen metingen verricht. Het gaat in dit onderzoek om het verschil tussen soorten vlees. Het is onduidelijk wat het aandeel van vlees is in de totale blootstelling aan ESBL-producerende bacteriën, omdat mensen ook via andere bronnen dan vlees daaraan worden blootgesteld. Voorbeelden zijn contacten met dieren, contacten tussen mensen, andere soorten voedsel zoals rauwe groenten en fruit en via het milieu, zoals door zwemmen in oppervlaktewater. Ook is niet duidelijk in welke mate mensen door de blootstelling via vlees daadwerkelijk drager worden van deze bacterie. Bovendien wordt niet iedere drager ziek van een resistente bacterie.

Onderzocht is of het wonen in de buurt van veehouderijen effect kan hebben op de gezondheid van de omwonenden. Hieruit komen een aantal positieve en een aantal negatieve gezondheidseffecten naar voren. Een eenduidig antwoord is dan ook niet te geven. Aangetoond is dat mensen die rondom veehouderijen wonen minder astma en allergieën hebben. Dicht bij veehouderijen wonen minder mensen met COPD, een chronische ziekte aan de longen. Daar staat tegenover dat de mensen in deze omgeving die wel COPD hebben, daar vaker en/of ernstigere complicaties van hebben. Verder is er een verband gevonden tussen wonen nabij veehouderijen en een verlaagde longfunctie. Dit wordt waarschijnlijk veroorzaakt door stoffen die afkomstig zijn van de veehouderij. Niet alleen dichtbij veel veehouderijen wonen zorgt voor een lagere longfunctie. De longfunctie wordt in het hele onderzoeksgebied lager op momenten dat de concentratie van ammoniak (een stof die afkomstig is van mest) in de lucht hoog is. Deze effecten zijn vergelijkbaar met de schadelijke gezondheidseffecten van verkeer in een stad. De onderzoekers vonden dat er meer longontstekingen in het onderzoeksgebied voorkomen dan in de rest van het land; een verschil dat na de Q-koorts-epidemie van 2007-2010 wel kleiner is geworden. Er werd een verband gevonden tussen pluimveehouderijen binnen 1 kilometer afstand van de woning en een licht verhoogde kans op longontsteking. Het is onduidelijk of de extra longontstekingen in dit onderzoeksgebied worden veroorzaakt door specifieke ziekteverwekkers die van dieren afkomstig zijn (zoönose-verwekkers), of dat mensen gevoeliger voor longontsteking worden door de blootstelling aan stoffen die veehouderijbedrijven uitstoten, zoals fijnstof, endotoxines (onderdelen van micro-organismen) en ammoniak. In het onderzoek is ook gekeken of bepaalde zoönoseverwekkers vaker voorkomen in de omgeving van veehouderijen ten opzichte van de rest van het land. Bij het hepatitis E-virus, de bacterie Clostridium difficile en ESBL-producerende bacteriën is dat niet het geval. Wel lijken mensen iets vaker drager te zijn van de veegerelateerde MRSA-bacterie. Of deze verhoging komt door uitstoot vanuit veehouderijen is nog onduidelijk. Dit zijn de belangrijkste conclusies uit het VGO-onderzoek dat is uitgevoerd door het RIVM, de Universiteit Utrecht (IRAS), Wageningen UR en het NIVEL. Het onderzoek is uitgevoerd in het oostelijk deel van Noord-Brabant en in Noord-Limburg. Sommige resultaten zijn mogelijk alleen van toepassing op het onderzochte gebied. Dat komt doordat lokale kenmerken, bijvoorbeeld luchtvervuiling uit omliggende industriegebieden, van invloed zijn op de bevindingen.

OBJECTIVES: In the Netherlands there is an ongoing debate regarding environmental health risks of livestock farming for neighbouring residents. This explorative study aims to determine the prevalence of carriage of ESBL/pAmpC-producing Enterobacteriaceae (ESBL/pAmpC-E) in the general population living in a livestock-dense area, and to study associations between determinants, including exposure through contact with animals and the environment, and human carriage of ESBL/pAmpC-E. METHODS: A cross-sectional study was performed among 2,432 adults (aged 20-72 years) in twelve temporary research centres in the south of the Netherlands, consisting of a questionnaire and analysis of a faecal sample to assess carriage of ESBL/pAmpC-E. Risk factors were analysed using logistic regression. RESULTS: The prevalence for carriage of ESBL/pAmpC-E was 4.5% (109/2,432; 95%CI: 3.7-5.4) ranging from 1.4-10.9% among the research centres. ESBL/pAmpC resistance genes were detected in E. coli and K. pneumoniae isolates obtained from these 109 persons and the most common ESBL-resistance genes were blaCTX-M-15, blaCTX-M-14/17, and blaCTX-M-1, originating from 76 participants. Travel in the last twelve months to Africa, Asia or Latin America (OR: 2.82 (95%CI: 1.71-4.63)), having kept cows for a hobby (last five years) (OR: 3.77 (95%CI: 1.22-11.64)), usage of proton-pump inhibitors (OR: 1.84 (95%CI: 1.05-3.23)), and living within 1,000 metres of a mink farm (OR: 2.26 (95%CI: 1.28-3.98)) were identified as risk factors. Exposure to poultry was not identified as a risk factor. CONCLUSIONS: Overall, living in close proximity of livestock animals and farms does not seem to be a risk factor for carriage of ESBL/pAmpC-E.

Escherichia fergusonii was introduced in the genus Escherichia almost 65 years later than Escherichia coli after which the genus was named. From then (1985) onwards mainly case reports on E. fergusonii associated with disease in individuals of veterinary or human origin have been reported and only very few more extensive studies became available. This has resulted in very fragmented knowledge on this organism. The aim of this manuscript is to give an overview of what is known on E. fergusonii today and to stimulate more research on this organism so that better insight can be obtained in the role that E. fergusonii plays in human and animal infections.

We isolated methicillin-resistant Staphylococcus aureus (MRSA) from cows with subclinical mastitis and from a person who worked with these animals. The bovine and human strains were indistinguishable by phenotyping and genotyping methods and were of a low frequency spa type. To our knowledge, this finding indicates the first documented case of direct transmission of MRSA between cows and humans.

Objectives To investigate the occurrence and characteristics of extended-spectrum β-lactamase (ESBL)- and AmpC-producing Enterobacteriaceae isolates in clinical samples of companion animals and horses and compare the results with ESBL/AmpC-producing isolates described in humans. Methods Between October 2007 and August 2009, 2700 Enterobacteriaceae derived from clinical infections in companion animals and horses were collected. Isolates displaying inhibition zones of ≤25 mm for ceftiofur and/or cefquinome by disc diffusion were included. ESBL/AmpC production was confirmed by combination disc tests. The presence of resistance genes was identified by microarray, PCR and sequencing, Escherichia coli genotypes by multilocus sequence typing and antimicrobial susceptibility by broth microdilution. Results Sixty-five isolates from dogs (n = 38), cats (n = 14), horses (n = 12) and a turtle were included. Six Enterobacteriaceae species were observed, mostly derived from urinary tract infections (n = 32). All except 10 isolates tested resistant to cefotaxime and ceftazidime by broth microdilution using clinical breakpoints. ESBL/AmpC genes observed were blaCTX-M-1, -2, -9, -14, -15,blaTEM-52, blaCMY-2 and blaCMY-39. blaCTX-M-1 was predominant (n = 17). blaCTX-M-9 occurred in combination with qnrA1 in 3 of the 11 Enterobacter cloacae isolates. Twenty-eight different E. coli sequence types (STs) were found. E. coli carrying blaCTX-M-1 belonged to 13 STs of which 3 were previously described in Dutch poultry and patients. Conclusions This is the first study among a large collection of Dutch companion animals and horses characterizing ESBL/AmpC-producing isolates. A similarity in resistance genes and E. coli STs among these isolates and isolates from Dutch poultry and humans may suggest exchange of resistance between different reservoirs.

Momenteel kunnen er geen wetenschappelijk onderbouwde uitspraken worden gedaan over het infectierisico van omwonenden van veehouderijen, met uitzondering van Q-koorts. Het is aangetoond dat omwonenden van melkgeitenbedrijven met Q-koorts, een verhoogd risico hebben om deze infectieziekte te krijgen. Voor de overige zoönosen (infectieziekten die van dier op mens worden overgedragen) zijn onvoldoende gegevens beschikbaar over het risico in relatie tot de afstand tot veehouderijen, het bedrijfstype en de bedrijfsgrootte. Wel is bekend dat veehouders, medewerkers op veehouderijen en dierenartsen een verhoogd risico hebben om bepaalde zoönosen op te lopen. Direct contact met dieren is daarbij vaak een risicofactor.

In 2005, a distinct clone of methicillin resistant Staphylococcus aureus (MRSA CC398) was found in pigs and people in contact with pigs. The structure of the pig production chain in high technology pig husbandry enables pathogens to spread during animal trading, with an increasing prevalence in herds further down the chain. The objective of this study was to quantify the effect of the MRSA status of the supplying herd on the MRSA status of the receiving herd in order to gain more insight into the role of animal trading as a transmission route for MRSA CC398. Nasal samples (60–80 pigs per herd) were collected from 38 herds; in 20 herds, environmental samples were collected as well. Ten MRSA-positive herds (based on the results of nasal swabs of 10 individual pigs per herd) from a prior study were included in the data analysis. Herds were classified as MRSA positive if at least one sample tested positive. The 48 herds were part of 14 complete (40 herds) and 4 incomplete (8 herds) pig production chains. Fifty-six percent of the herds were classified as MRSA positive. MRSA-positive herds were observed at the start (breeding herds), middle (farrowing herds) and the end (finishing herds) of the pig production chain. All of the herds in 8 chains tested MRSA positive;, all of the herds in 5 chains tested MRSA negative and in the remaining 5 chains, MRSA-positive and MRSA-negative herds were detected. Seven spa types were found, which were all previously confirmed to belong to CC398. All of the isolates were susceptible to mupirocin, linezolid, rifampicin, fusidic acid and cotrimoxazole. Resistance against tetracycline, erythromycin and clindamycin was found in 100, 74 and 76% of the isolates, respectively. Seventy-nine percent of herds with a MRSA-positive supplier of pigs were MRSA positive, whereas 23% of herds with a MRSA-negative supplier were MRSA positive (OR = 10.8; 95% CI: 1.5–110.1; P = 0.011). The presence of entirely MRSA-positive and MRSA-negative chains and the strong association between the MRSA status of herds and their suppliers illustrates a large risk associated with purchasing pigs from MRSA-positive herds; a top-down strategy for future control programs is, therefore, a basic requirement. However, 23% of herds with a MRSA-negative supplier were MRSA positive and furthermore, 46% of the herds at the top of the pig production chain without a supplier tested MRSA positive. This underlined the need for the identification of additional risk factors for MRSA.

Aan het Veterinair Microbiologisch Diagnostisch Centrum (VMDC) van de faculteit Diergeneeskunde wordt regelmatig de vraag gesteld of gezelschapsdieren de bron van besmetting met meticillinerestistente Staphylococcus aureus (MRSA) bij de mens kunnen zijn en of zij een rol kunnen spelen bij een falende eradicatiebehandeling van mensen.

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an emerging pathogen in dogs and has been found in Europe, Asia and North America. To date most studies are one-point prevalence studies and therefore little is known about the dynamics of MRSP in dogs and their surrounding. In this longitudinal study MRSP colonization in dogs and the transmission of MRSP to humans, contact animals and the environment was investigated. Sixteen dogs with a recent clinical MRSP infection were included. The index dogs, contact animals, owners and environments were sampled once a month for six months. Samples taken from the nose, perineum and infection site (if present) of the index cases and contact animals, and the nares of the owners were cultured using pre-enrichment. Index cases were found positive for prolonged periods of time, in two cases during all six samplings. In five of the 12 households that were sampled during six months, the index case was intermittently found MRSP-positive. Contact animals and the environment were also found MRSP-positive, most often in combination with a MRSP-positive index dog. In four households positive environmental samples were found while no animals or humans were MRSP-positive, indicating survival of MRSP in the environment for prolonged periods of time. Genotyping revealed that generally similar or indistinguishable MRSP isolates were found in patients, contact animals and environmental samples within the same household. Within two households, however, genetically distinct MRSP isolates were found. These results show that veterinarians should stay alert with (former) MRSP patients, even after repeated MRSP-negative cultures or after the disappearance of the clinical infection. There is a considerable risk of transmission of MRSP to animals in close contact with MRSP patients. Humans were rarely MRSP-positive and never tested MRSP-positive more than once suggesting occasional contamination or rapid elimination of colonization of the owners.

The objective of this study was to investigate the prevalence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) in people, pets and the environment in households with a pet with a clinical MRSP-infection within the past year. Personnel and the environment at veterinary clinics were also screened. Nasal swabs (humans), nasal and perineal swabs (pets) and environmental wipes were examined using selective culturing. Twenty households were enrolled; 10/20 index cases still had clinical signs of infection at the start of the study and all were MRSP-positive. Of the remaining 10 index cases five were MRSP-positive in nasal and/or perineal samples. Five of 14 (36%) contact dogs and four of 13 (31%) contact cats were found MRSP-positive. In the households with an index case with clinical signs of infection 6/7 (86%) contact animals were MRSP-positive. MRSP was cultured from 2/45 (4%) human nasal samples. Domestic contamination was widespread as positive samples were found in 70% of the households and 44% of all environmental samples were MRSP-positive. In all but one of these MRSP-positive households the index case was still MRSP positive. Among the personnel in veterinary clinics 4/141 (3%) were MRSP-positive. MRSP was cultured from 31/200 environmental samples in 7/13 clinics at the first sampling and in 3/6 clinics the environment remained MRSP-positive after cleaning and disinfection indicating that current cleaning procedures often were unable to eliminate MRSP. These results show that transmission of MRSP between infected or colonized dogs and cats and healthy people does occur but is relatively uncommon, while transmission to contact pets occurs frequently, especially when the index case still has clinical signs of MRSP-infection.

Background: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) often display resistance to almost all classes of antimicrobial agents used in veterinary medicine. In the present study, we investigated the emergence of rifampicin resistance in MRSP, the persistence of these isolates and identified the corresponding mutations in the rpoB gene. Methods: In addition to two rifampicin-resistant MRSP isolates from a multicentre study, consecutive MRSP isolates collected prior to and after rifampicin therapy from nine dogs at five Dutch veterinary hospitals were included in this study. The isolates were tested for resistance to rifampicin and other antimicrobial agents. The rifampicin resistance-determining region (RRDR) within the rpoB gene of the rifampicin-resistant and -susceptible isolates was amplified by PCR and sequenced. PFGE served to determine the genetic relationships of the MRSP isolates. Results: Two MRSP isolates of the multicentre study showed mutations at position 513 or 522 in the RRDR of the rpoB gene. In contrast to the rifampicin-susceptible isolates, all rifampicin-resistant MRSP isolates showed mutations at one or two of the amino acid positions 508, 509, 513, 516, 522, 526 and 531. In most strains, a single amino acid exchange was observed. PFGE analysis confirmed that the rifampicin-resistant MRSP isolates were indistinguishable from or closely related to the rifampicin-susceptible isolate obtained from the same dog prior to rifampicin application. Conclusions: Therapy of MRSP infections with rifampicin results in the rapid emergence of rifampicin resistance and these isolates can persist for months. As a consequence, single therapy with rifampicin is not recommended.

The objective of this study was to investigate the prevalence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) in people, pets and the environment in households with a pet with a clinical MRSP-infection within the past year. Personnel and the environment at veterinary clinics were also screened. Nasal swabs (humans), nasal and perineal swabs (pets) and environmental wipes were examined using selective culturing. Twenty households were enrolled; 10/20 index cases still had clinical signs of infection at the start of the study and all were MRSP-positive. Of the remaining 10 index cases five were MRSP-positive in nasal and/or perineal samples. Five of 14 (36%) contact dogs and four of 13 (31%) contact cats were found MRSP-positive. In the households with an index case with clinical signs of infection 6/7 (86%) contact animals were MRSP-positive. MRSP was cultured from 2/45 (4%) human nasal samples. Domestic contamination was widespread as positive samples were found in 70% of the households and 44% of all environmental samples were MRSP-positive. In all but one of these MRSP-positive households the index case was still MRSP positive. Among the personnel in veterinary clinics 4/141 (3%) were MRSP-positive. MRSP was cultured from 31/200 environmental samples in 7/13 clinics at the first sampling and in 3/6 clinics the environment remained MRSP-positive after cleaning and disinfection indicating that current cleaning procedures often were unable to eliminate MRSP. These results show that transmission of MRSP between infected or colonized dogs and cats and healthy people does occur but is relatively uncommon, while transmission to contact pets occurs frequently, especially when the index case still has clinical signs of MRSP-infection.

INTRODUCTION: Recently a specific MRSA sequence type, ST398, emerged in food production animals and farmers. Risk factors for carrying MRSA ST398 in both animals and humans have not been fully evaluated. In this cross-sectional study, we investigated factors associated with MRSA colonization in veal calves and humans working and living on these farms. METHODS: A sample of 102 veal calf farms were randomly selected and visited from March 2007-February 2008. Participating farmers were asked to fill in a questionnaire (n = 390) to identify potential risk factors. A nasal swab was taken from each participant. Furthermore, nasal swabs were taken from calves (n = 2151). Swabs were analysed for MRSA by selective enrichment and suspected colonies were confirmed as MRSA by using slide coagulase test and PCR for presence of the mecA-gene. Spa types were identified and a random selection of each spa type was tested with ST398 specific PCR. The Sequence Type of non ST398 strains was determined. Data were analyzed using logistic regression analysis. RESULTS: Human MRSA carriage was strongly associated with intensity of animal contact and with the number of MRSA positive animals on the farm. Calves were more often carrier when treated with antibiotics, while farm hygiene was associated with a lower prevalence of MRSA. CONCLUSION: This is the first study showing direct associations between animal and human carriage of ST398. The direct associations between animal and human MRSA carriage and the association between MRSA and antimicrobial use in calves implicate prudent use of antibiotics in farm animals.

Background: The objective was to investigate the phenotypic and genotypic resistance and the horizontal transfer of resistance determinants from Salmonella isolates from humans and animals in Vietnam. Methodology/Principal Findings: The susceptibility of 297 epidemiologically unrelated non-typhoid Salmonella isolates was investigated by disk diffusion assay. The isolates were screened for the presence of class 1 integrons and Salmonella genomic island 1 by PCR. The potential for the transfer of resistance determinants was investigated by conjugation experiments. Resistance to gentamicin, kanamycin, chloramphenicol, streptomycin, trimethoprim, ampicillin, nalidixic acid, sulphonamides, and tetracycline was found in 13 to 50% of the isolates. Nine distinct integron types were detected in 28% of the isolates belonging to 11 Salmonella serovars including S. Tallahassee. Gene cassettes identified were aadA1, aadA2, aadA5, blaPSE-1, blaOXA-30, dfrA1, dfrA12, dfrA17, and sat, as well as open reading frames with unknown functions. Most integrons were located on conjugative plasmids, which can transfer their antimicrobial resistance determinants to Escherichia coli or Salmonella Enteritidis, or with Salmonella Genomic Island 1 or its variants. The resistance gene cluster in serovar Emek identified by PCR mapping and nucleotide sequencing contained SGI1-J3 which is integrated in SGI1 at another position than the majority of SGI1. This is the second report on the insertion of SGI1 at this position. High-level resistance to fluoroquinolones was found in 3 multiresistant S. Typhimurium isolates and was associated with mutations in the gyrA gene leading to the amino acid changes Ser83Phe and Asp87Asn. Conclusions: Resistance was common among Vietnamese Salmonella isolates from different sources. Legislation to enforce a more prudent use of antibiotics in both human and veterinary medicine should be implemented by the authorities in Vietnam.

Background: We present an easily applicable test for rapid binary typing of Staphylococcus aureus: binary interspace (IS) typing. This test is a further development of a previously described molecular typing technique that is based on length polymorphisms of the 16S-23S rDNA interspace region of S. aureus. Methodology/Principal Findings: A novel approach of IS-typing was performed in which binary profiles are created. 424 human and animal derived MRSA and MSSA isolates were tested and a subset of these isolates was compared with multi locus sequence typing (MLST) and Amplified Fragment Length Polymorphism (AFLP). Binary IS typing had a high discriminatory potential and a good correlation with MLST and AFLP. Conclusions/Significance: Binary IS typing is easy to perform and binary profiles can be generated in a standardized fashion. These two features, combined with the high correlation with MLST clonal complexes, make the technique applicable for large-scale inter-laboratory molecular epidemiological comparisons.

Citation for published version: Kadlec, K, Schwarz, S, Perreten, V, Andersson, UG, Finn, M, Greko, C, Moodley, A, Kania, SA, Frank, LA, Bemis, DA, Franco, A, Iurescia, M, Battisti, A, Duim, B, Wagenaar, JA, van Duijkeren, E, Weese, JS, Fitzgerald, JR, Rossano, A & Guardabassi, L 2010, 'Molecular analysis of methicillin-resistant Staphylococcus pseudintermedius of feline origin from different European countries and North America' Journal of Antimicrobial Chemotherapy, vol 65, no. 8, pp. 1826-1828., 10.1093/jac/dkq203

Resistance to third and fourth generation cephalosporins is rapidly increasing in bacteria infecting humans. Although many of these problems are linked to human to human transmission and to use of antimicrobials in human medicine, the potential role of community reservoirs such as food producing animals needs to be scrutinized. Resistance to third and fourth generation cephalosporins is emerging in enteric bacteria of food producing animals and also in food of animal origin. The genes encoding resistance to these cephalosporins are transferrable and often linked to other resistance genes. Systemic use of third and fourth cephalosporins selects for resistance, but co-selection by other antimicrobials is also likely to influence prevalence of resistance. Although there are many uncertainties, the potential consequences of a further increase of resistance to this critically important class of antimicrobials in bacteria colonising animals are serious. Measures to counter a further increase and spread of resistance among animals should therefore be considered., IT; en; stefano.morabito@iss.it

Since the emergence of MRSA in livestock, screening of animals for the detection of MRSA is widely practised. Different procedures are published for animal samples but a systematic comparison of methods has not been performed. The objective of this study was to compare three available commonly used procedures and three chromogenic agars; for detecting MRSA in nasal swabs from pigs (n = 70) and veal calves (n = 100). Procedures 1 and 2 used a pre-enrichment comprising Mueller Hinton broth with 6.5% NaCl followed by selective enrichment with 4 mu g/ml oxacillin + 75 mu g/ml aztreonam (procedure 1) and 5 mu g/ml ceftizoxime + 75 mu g/ml aztreonam (procedure 2) respectively. Procedure 3 used a selective enrichment broth only, containing 4% NaCl, 5 mu g/ml ceftizoxime + 50 mu g/ml aztreonam. After selective enrichment, media were streaked on to three different chromogenic agars. Significantly more MRSA were found for pig as well as for veal calf samples with procedures 1 and 2. No significant differences were found between procedures 1 and 2. For nasal swabs from pigs significantly more MRSA-positive samples were found when MRSA Screen (Oxoid) or MRSASelect (TM) (Bio-Rad) agars were used compared to MSRA ID (bioMerieux). For calf samples no significant differences between the different agars were found. In conclusion, the results of this study show that procedures 1 and 2, both using additional high salt pre-enrichment are superior and should be recommended for MRSA detection in nasal swabs from pigs and veal calves. The preferred choice of chromogenic agar depends on the sample matrix.

In October 2008 nine farrow-to-finish pig farms were visited in Shuangliu County in Sichuan Province, China. One farm was empty for one month but not cleaned after depopulation. Dust samples were collected at each farm and analysed for the presence of methicillin-resistant Staphylococcus aureus (MRSA). Dust samples from four farms were also analysed for the presence of methicillin-susceptible S. aureus (MSSA). On 5/9 farms MRSA was isolated and on 2/4 farms MSSA was isolated. On two farms, including the empty farm, no MRSA or MSSA could be detected. All MRSA isolates (n = 43) belonged to spa type t899. MSSA isolates belonged to spa type t899 (n = 12) and spa type t034 (n = 2). From 4/9 farms the MRSA isolates of spa type t899 were assigned to multilocus sequence type (MLST) ST9 whereas on one farm the MRSA spa type t899 isolates belonged to a single locus variant of MLST ST9 (ST1376). MSSA isolates with spa type t899 belonged to MLST ST9 and the MSSA with spa type t034 belonged to MLST ST398. This is the first report on MRSA in pig farms in China and the first time that MRSA ST9 and a single locus variant of ST9 are detected in pig farms. This study shows that livestock associated MRSA is not restricted to clonal lineage ST398 as found in Europe and Northern America in commercial pigs but that other MRSA lineages are able to spread in livestock as well. The study confirms that livestock may act as a reservoir for MRSA.