Sharing more than friendship - nasal colonization with coagulase-positive staphylococci (CPS) and co-habitation aspects of dogs and their owners

Background Since the relationship between dogs and their owners has changed, and dogs moved from being working dogs to family members in post-industrial countries, we hypothesized that zoonotic transmission of opportunistic pathogens like coagulase positive staphylococci (CPS) is likely between dogs and their owners. Methodology/Principal Findings CPS- nasal carriage, different aspects of human-to-dog relationship as well as potential interspecies transmission risk factors were investigated by offering nasal swabs and a questionnaire to dog owners (108) and their dogs (108) at a dog show in 2009. S. aureus was found in swabs of 20 (18.5%) humans and two dogs (1.8%), and spa types which correspond to well known human S. aureus lineages dominated (e.g. CC45, CC30 and CC22). Multilocus sequence typing (MLST) of the two canine strains revealed ST72 and ST2065 (single locus variant of ST34). Fifteen dogs (13.9%) and six owners (5.6%) harboured S. pseudintermedius, including one mecA-positive human isolate (MRSP). Pulsed field gel electrophoresis (PFGE) revealed that one dog/owner pair harboured indistinguishable S. pseudintermedius- isolates of ST33. Ten (48%) of the 21 S. pseudintermedius-isolates showed resistance towards more than one antimicrobial class. 88.9% of the dog owners reported to allow at least one dog into the house, 68.5% allow the dog(s) to rest on the sofa, 39.8% allow their dogs to come onto the bed, 93.5% let them lick their hands and 52.8% let them lick their face. Bivariate analysis of putative risk factors revealed that dog owners who keep more than two dogs have a significantly higher chance of being colonized with S. pseudintermedius than those who keep 1–2 dogs (p<0.05). Conclusions/Recommendations In conclusion, CPS transmission between dog owners and their dogs is possible. Further investigation regarding interspecies transmission and the diverse adaptive pathways influencing the epidemiology of CPS (including MRSA and MRSP) in different hosts is needed

Sharing More than Friendship — Nasal Colonization with Coagulase-Positive Staphylococci (CPS) and Co-Habitation Aspects of Dogs and Their Owners

BACKGROUND: Since the relationship between dogs and their owners has changed, and dogs moved from being working dogs to family members in post-industrial countries, we hypothesized that zoonotic transmission of opportunistic pathogens like coagulase positive staphylococci (CPS) is likely between dogs and their owners. METHODOLOGY/PRINCIPAL FINDINGS: CPS- nasal carriage, different aspects of human-to-dog relationship as well as potential interspecies transmission risk factors were investigated by offering nasal swabs and a questionnaire to dog owners (108) and their dogs (108) at a dog show in 2009. S. aureus was found in swabs of 20 (18.5%) humans and two dogs (1.8%), and spa types which correspond to well known human S. aureus lineages dominated (e.g. CC45, CC30 and CC22). Multilocus sequence typing (MLST) of the two canine strains revealed ST72 and ST2065 (single locus variant of ST34). Fifteen dogs (13.9%) and six owners (5.6%) harboured S. pseudintermedius, including one mecA-positive human isolate (MRSP). Pulsed field gel electrophoresis (PFGE) revealed that one dog/owner pair harboured indistinguishable S. pseudintermedius- isolates of ST33. Ten (48%) of the 21 S. pseudintermedius-isolates showed resistance towards more than one antimicrobial class. 88.9% of the dog owners reported to allow at least one dog into the house, 68.5% allow the dog(s) to rest on the sofa, 39.8% allow their dogs to come onto the bed, 93.5% let them lick their hands and 52.8% let them lick their face. Bivariate analysis of putative risk factors revealed that dog owners who keep more than two dogs have a significantly higher chance of being colonized with S. pseudintermedius than those who keep 1-2 dogs (p<0.05). CONCLUSIONS/RECOMMENDATIONS: In conclusion, CPS transmission between dog owners and their dogs is possible. Further investigation regarding interspecies transmission and the diverse adaptive pathways influencing the epidemiology of CPS (including MRSA and MRSP) in different hosts is needed

Vergleichende genotypische Charakterisierungen von Methicillin-resistenten und -empfindlichen Staphylococcus pseudintermedius Isolaten von Katzen und Hunden in Deutschland

Staphylococcus pseudintermedius, a member of the Staphylococcus intermedius- group, is known as a common colonizer of canine skin and mucosa, occasionally detected in specimens of other animal species and humans as well. Being a representative of a typical opportunistic pathogen, S. pseudintermedius is often associated with a wide variety of purulent or toxin-associated infectiouse diseases in animals as well as occasionally in humans. Despite increasing reports concerning the occurence of S. pseudintermedius, including its methicillin resistant variant (MRSP), in recent years, knowledge about the occurrence and distribution of genotypes together with important toxins in specimens from diseased dogs, cats and horses in Germany is scarce. MRSP are often associated with a multi-drug resistant phenotype, limiting effective antibiotic therapy options in veterinary medicine. In some cases, animals have to be put down due to reasons of animal welfare. The aim of this study was to investigate the genetic background and relationships among a predefined set of 220 S. pseudintermedius isolates representing different host origins (dog, cat, horse), various infected sites (e.g. surgical site infection (SSI), wound, otitis, skin and skin-associated structures) including methicillin- resistant (n=107) and -susceptible (n=113) variants. Genotypic characterization was performed by conducting pulsed-field gel electrophoresis (PFGE) for all S. pseudintermedius as well as multi-locus sequence typing (MLST) for 53 methicillin-susceptible (MSSP) and 55 methicillinresistant S. pseudintermedius (MRSP). In addition, the occurrence and distribution of important virulence factors such as exfoliative toxins (ExpA, ExpB) and leukotoxin (LukI) among the isolate collection was determined by PCR detection of the respective encoding genes and subsequently analyzed with respect to different genetic lineages. All investigated MSSP and MRSP yielded a positive PCR-result for lukI. Furthermore, expA was detected in 18/113 of MSSP (15.9%), but not among MRSP. In addition, expB was identified in 23/113 of MSSP (20.4%) and 1/107 of MRSP (0.9%), respectively. With regard to the sample site origin distribution, MSSP isolates obtained from either “skin” or “skin-associated structures” were with 16% (expA) and 12% (expB) equal or even below the overall average. Interestingly, MSSP isolated from wound swabs yielded positive PCR signals above the overall average, 30.8% for expA and 46.2% for expB. The putative impact of these toxins during development of wound infections might be an interesting aspect and should be further investigated in functional studies. In total, 219 of 220 S. pseudintermedius were typeable using the PFGE technique. Subsequent PFGE analysis and dendrogramm construction was carried out with Bionumerics 7.5 (Applied Maths, Belgium) using the Unweighted Pair Group Method with Arithmetic mean (UPGMA) employing an 80% cut-off for cluster dedication. In total, 20 distinct clusters as well as three singletons were assigned. Pattern of MSSP isolates clustered within 19 of the 20 clades and were associated with two of the three singletons described in this work. However, some MSSP patterns associated with isolates obtained from different animal species originating from different federal states seem to be closely related. This finding might indicate spread of various genetic lineages across large geographic regions. A putative explanation for this observation might be the mobility of the dog owners (e.g. holidays, relocation, dog shows etc.). Interestingly, the PFGE pattern of MRSP showed a remarkable diversity, an observation which has been published in different studies from other countries as well. Several MRSP revealed identical patterns, although these isolates originated from distinct animal patients living in different federal states. MLST analysis revealed 50 novel sequence types (ST) associated with the MSSP and one sequence type (ST370) that has been reported in a previous study. In contrast, the predominant genotype assigned to 48 of 55 MRSP isolates obtained from various German regions, animals and infected sites determined in this study was ST71. PFGE analysis revealed that the majority of MRSP investigated by MLST (39 of 55) clustered within the largest clade (clade 8). However, further PFGE patterns associated with MRSP_ST71 clustered within other clades as well. The apparent incongruence of MLST and PFGE data for S. pseudintermedius, especially for MRSP_ST71, has previously been described in other studies as well. The use of an in silico restriction analysis based on whole genome data might elucidate DNA sequence modifications of the SmaI restriction sites possibly responsible for this discrepancy between results of MLST and PFGE analysis. In addition, the MLST scheme currently used for S. pseudintermedius might lack discriminatory power. At present, the MLST database includes more than 600 different data base entries. However, for the gene tuf only 12 variants have so far been identified. Although ST71 is the predominant genetic lineage for MRSP investigated in this study, a diversification of MRSP sequence types was observed as well, consistent with recent publications. In addition, two novel MRSP genotypes (ST461 and ST525) were identified during this work. Furthermore, ST258 – an emerging genetic lineage identified in Northern Europe - was also detected in the present MRSP collection. This current evolvement seems to be similar to the evolution of methicillin-resistant S. aureus (MRSA) in the past, where several different genetic lineages seem to be capable of aquiring and integrating the mobile genetic element(s) harboring the methicillin resistance encoding gene. The future will show, whether MRSP infections will remain largely restricted to veterinary medicine or if serious infections in humans will occur more frequently.Staphylococcus pseudintermedius, ein Vertreter der Staphylococcus intermedius- Gruppe (SIG), gehört zu den gewöhnlichen Besiedlern der Haut und Schleimhäute von Hunden und kommt gelegentlich auch bei anderen Haustieren vor. Als typischer opportunistischer Infektionserreger kann S. pseudintermedius eine Vielzahl von purulenten sowie Toxinvermittelten Erkrankungen bei Tieren und gelegentlich auch bei Menschen induzieren bzw. sekundär ein bereits bestehendes Krankheitsbild verschlechtern. Trotz zahlreicher Berichte über das Auftreten von S. pseudintermedius sowie der Methicillin-resistenten Variante (MRSP) in der jüngsten Vergangenheit ist über das Vorkommen bestimmter Genotypen und deren Toxine bei Erkrankungen von Hunden, Katzen und Pferden in Deutschland bislang wenig bekannt. MRSP-Infektionen sind für Veterinärmediziner ein therapeutisches Problem, da die betroffenen Tiere aufgrund des meist multi-resistenten Phänotyps dieser Infektionserreger oftmals nur schwer antibiotisch zu versorgen sind und in Einzelfällen sogar eingeschläfert werden müssen. Im Rahmen dieser Arbeit sind daher 220 Isolate aus ganz Deutschland, einschließlich 113 Methicillin-empfindlicher (MSSP) und 107 -resistenter (MRSP) Isolate zunächst mittels PFGE typisiert worden. Anschließend wurden insgesamt 108 Isolate (53 MSSP und 55 MRSP), welche das gesamte Spektrum der auftretenden PFGE-Cluster repräsentieren, mittels MLST charakterisiert. Zudem sind alle Isolate auf Gene für die bedeutenden Virulenzfaktoren Leukozidin (LukI) sowie Varianten eines exfoliativen Toxins (ExpA, ExpB) untersucht worden. Alle MSSP und MRSP waren lukI positiv, während für expA nur 18 der MSSP und keiner der MRSP (15,9% / 0%) und für expB 23 der MSSP und ein MRSP positiv waren (20,4% / 0.9%). Insgesamt wurde bei detaillierter Betrachtung der Ergebnisse für MSSP deutlich, dass die Isolate mit Vorbericht „Abstrich von Haut oder Haut-assoziierten Strukturen“nur nahe bzw. unter dem Gesamt-Durchschnitt von ca. 16% für expA und 20% für expB lagen, während der Anteile für Isolate aus Wundabstrichen mit 30,8% (expA) und 46,2% (expB) deutlich über dem Durchschnitt lagen. Der potentielle Einfluss dieser Toxine auf die Entwicklung einer Wundinfektion ist ein interessanter Aspekt, der in Rahmen von weiteren Untersuchungen zur Virulenz von S. pseudintermedius aufgegriffen werden sollte. Mittels Pulsfeld- Gelelektrophorese (PFGE) konnten Bandenmuster von 219 der 220 Isolate dargestellt werden. Die Auswertung der PFGE-Bandenmuster mittels unweighed pair group method using arithmetic averages (UPGMA) ergab insgesamt 20 Cluster sowie 3 Einzelmuster bei Nutzung eines cut-offs bei 80%. Die Bandenmuster der MSSP-Isolate verteilten sich auf 19 der insgesamt 20 Cluster und stellten zwei der drei Einzelmuster. Dennoch sind in mehreren Fällen sehr ähnliche Muster bei MSSP-Isolaten von unterschiedlichen Patienten aus verschiedenen Bundesländern nachgewiesen worden, was die Verbreitung zahlreicher Genotypen über ein großes geographisches Gebiet andeutet. Gründe hierfür könnten z.B. in der allgemeinen Mobilität der Hundehalter (Urlaub, Umzug, Hundetreffen) liegen. Die Diversität der Bandenmuster von MRSP aus Deutschland ist hoch, eine Beobachtung, die auch in anderen Ländern gemacht wurde. Während für MSSP eine Vielzahl von Sequenztypen detektiert wurde (davon war einer bereits aus einer anderen Studie bekannt und 50 neu) dominierte bei den MRSP der ST71, der offensichtlich in ganz Deutschland verbreitet ist. 48 der mittels MLST untersuchten 55 MRSP aus unterschiedlichen Bundesländern und medizinischen Indikationen sind dieser genetischen Linie zuzuordnen. Die überwiegende Mehrzahl dieser Isolate (39 von 55) ließ sich dem PFGE Cluster 8 zuordnen, aber MRSP_ST71 sind auch in anderen PFGE Clustern aufgetreten. Diese Beobachtung der Inkongruenz zwischen PFGE und MLST Daten für S. pseudintermedius und insbesondere für MRSP_ST71 ist in der Literatur bereits beschrieben. Eine in silico Restriktionsanalyse auf Basis von Ganzgenomdaten könnte zeigen, welche Änderungen an den Schnittstellen der hier gewählten Endonuklease SmaI möglicherweise zu der weltweit beobachteten Diskrepanz zwischen PFGE und MLST-Analysen führen. Auch das verwendete MLST Schema könnte möglicherweise eine zu geringe Repräsentativität aufweisen, z.B. gibt es für das Gen tuf bei über 600 Datenbankeinträgen nur 12 Varianten. Die in aktuellen Studien beschriebene Diversifikation der MRSP-STs. spiegelt sich jedoch auch in dieser Studie wider. Zwei bislang nicht beschriebene STs für MRSP wurden identifiziert (ST461, ST525). Ferner ist ein in Nordeuropa als epidemisch beschriebener Genotyp (ST258) auch in dieser Studie nachgewiesen worden. Diese aktuelle Entwicklung scheint für MRSP ähnlich zu verlaufen wie für Methicillin-resistente Staphylococcus aureus (MRSA) in der Vergangenheit, eine Vielzahl von genetischen Linien ist scheinbar auch in dieser Spezies in der Lage, das Resistenz-tragendende und mobilisierbare genetische Element aufzunehmen. Die weitere Zukunft wird zeigen, ob diese Problematik hauptsächlich auf den Bereich Veterinärmedizin beschränkt bleibt oder ob sich auch die Fälle der schweren Infektionen beim Menschen durch MRSP häufen

Risk factors for <i>S. pseudintermedius</i> colonization among dog owners sampled during a dog show event in Berlin in 2009 (n = 108) (bivariate analysis).

<p>Abbreviations:</p><p>f, female; m, male;</p>*<p>not calculated.</p><p>OR: Odds ratio.</p><p>CI: Confidence interval.</p

Molecular characteristics of <i>S. aureus</i> from the nasal cavity of dog owners and dogs.

1<p>Strain collection number: IMT: Institute of Microbiology and Epizootics, RKI: Robert Koch-Institute (Wernigerode branch).</p>2<p>Individual number for each of the participating dog/dog owner pairs.</p>3<p><i>italic:</i> new <i>spa</i> types.</p>4<p>ST determined according to MLST result (bold),</p>*<p>predicted CC according to (<a href="http://www.ridom.de" target="_blank">www.ridom.de</a>), n.p.: not predictable.</p

Descriptive characteristics of dog owners.

<p>Descriptive characteristics of dog owners.</p

Comparative PFGE analysis and strain characteristics of <i>S. pseudintermedius</i> from human and canine origin.

<p>Dendrogram (percent similarity) showing DNA restriction pattern after digestion with <i><u>Sma</u></i>I for all 21 MSSP and MRSP isolates. PFGE analysis by use of bionumerics® (unweighted-pair group method using average linkages), dice coefficient, 1.2% tolerance and 0.5% optimization. Pair 36 comprised the isolates IMT18797 (canine) and IMT18798 (human), which show indistinguishable PFGE pattern. The canine isolate IMT18789 and IMT18828 (human) share an indistinguishable pulsotype as well, although they did not compose a dog/dog owner pair. ¹Strain collection number: IMT: Institute of Microbiology and Epizootics. RKI: Robert Koch-Institute (Wernigerode branch). ²Individual number for each of the participating dog/dog owner pairs. ³Determined by use of VITEK® 2 (bioMerieux) according to the manufacturers instructions. ⁴Allelic profile of the genes <i>pta</i>, <i>cpn</i>60, <i>tuf</i>, 16S rRNA and <i>agr</i>D. Abbreviations: PEN, Penicillin G; GEN, Gentamicin; KAN, Kanamycin; ENR, Enrofloxacin; MAR, Marbofloxacin; ERY, Erythromycin; CLI, Clindamycin; TET, Tetracycline; CHL, Chloramphenicol; i: susceptibility testing result: intermediate. Luk-I: Leukotoxin I (l<i>uk</i>S and <i>luk</i>F), <i>exp</i>A: Exfoliative toxin A (primer: this study), <i>exp</i>B: Exfoliative toxin B.</p