Dissemination of the gene encoding exfoliative toxin of Staphylococcus intermedius among strains isolated from dogs during routine microbiological diagnostics

Detection and characterization of potential virulence determinants in Staphylococcus pseudintermedius and S. schleiferi strains isolated from canine otitis externa in Korea

BACKGROUND

A recent increase in the occurrence of canine skin and soft tissue infections, including otitis externa and pyoderma, caused by antimicrobial-resistant Staphylococcus pseudintermedius and S. schleiferi has become a significant public and veterinary health issues.

OBJECTIVE

We investigated the virulence potentials associated with the occurrence of canine otitis externa in S. pseudintermedius and S. schleiferi.

METHODS

In this study, the prevalence of genes encoding leukocidins, exfoliative toxins, and staphylococcal enterotoxins (SEs) was investigated using previously characterized S. pseudintermedius (n = 26) and S. schleiferi (n = 19) isolates derived from canine otitis externa. Susceptibility to cathelicidins (K9CATH and PMAP-36) and hydrogen peroxide (H2O2) was also examined in both staphylococcal species.

RESULTS

A high prevalence of genes encoding leukocidins (lukS/F-I, lukS1/F1-S, and lukS2/F2-S), exfoliative toxins (siet, expB, and sset), and SEs was identified in both S. pseudintermedius and S. schleiferi isolates. Notably, S. pseudintermedius isolates possessed higher number of SE genes, especially newer SE genes, than S. schleiferi isolates harboring egc clusters. Although no significant differences in susceptibility to K9CATH and H2O2 were observed between the two isolate groups, S. pseudintermedius isolates exhibited enhanced resistance to PMAP-36 compared to S. schleiferi isolates.

CONCLUSIONS

These findings suggest that high a prevalence of various toxin genes together with enhanced resistance to cathelicidins may contribute to the pathogenicity of S. pseudintermedius and S. schleiferi in canine cutaneous infections.

Virulent potential of methicillin-resistant and methicillin-susceptible Staphylococcus pseudintermedius in dogs

Staphylococcus pseudintermedius is a zoonotic pathogen responsible for several infectious diseases in pet animals, yet its pathogenic potential is not fully understood. Thus, this study aims to unravel the virulence profile of S. pseudintermedius from canine origin. Methicillin-resistant (MRSP) and methicillin-susceptible (MSSP) strains were isolated from different infection sites and their genotypic and phenotypic features were compared to determine the clinical implications of MRSP and MSSP strains. Bacterial identification was performed using MALDI-TOF and 16S-rDNA sequencing. In addition, we used multilocus sequence typing (MLST) for strains' sequence type (ST) determination and phylogenetic relationship. The strains were screened for toxin genes, including cytotoxins (lukS, lukF), exfoliative toxin (siet), enterotoxins (sea, seb, sec, secCanine, sel, sem, and seq) and toxic shock syndrome toxin (tst-1). In vitro phenotypic analyses assessing antimicrobial susceptibility profile, biofilm formation ability, and expression of extracellular matrix components were performed. The investigated S. pseudintermedius strains belong to 17 unique ST, most of which were classified as ST71. MSSP and MRSP strains shared siet, lukS, and lukF virulence markers. Our findings showed that some MSSP strains also harbored sel, seq, and sem enterotoxin genes, suggesting a more diverse virulence profile. All MRSP strains and 77% of MSSP strains were classified as multidrug resistant (MDR). Moreover, all investigated S. pseudintermedius strains showed strong biofilm formation ability. In summary, our findings highlight the wide spread of highly virulent and drug-resistant zoonotic S. pseudintermedius strains, being a potential concern for One Health issues.

Antibiotic resistance, biofilm formation, and virulence factors of isolates of staphylococcus pseudintermedius from healthy dogs and dogs with keratitis

Canine bacterial keratitis is a common infection that can potentially threaten vision. Staphylococcus pseudintermedius (S. pseudintermedius) is an opportunistic pathogen that has been isolated from the canine conjunctival sac but there are only a few reports on the role of this bacterium in canine keratitis. This study focused on the distribution rate of S. pseudintermedius in the canine conjunctival sac, and the antibiotic resistance, biofilm-producing ability, and dissemination of virulence factors in strains of S. pseudintermedius isolated from healthy dogs and dogs with keratitis. The study included 35 healthy dogs and 40 dogs with keratitis. Bacterial species were confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI–TOF MS). Strains of S. pseudintermedius were screened for resistance against nine different antibiotics by the Kirby–Bauer assay. The ability to produce biofilm was investigated by microtiter plate assay (MtP) and amplification of icaA and icaD genes. Virulence factors in the strains were also evaluated. A total of 132 aerobic bacteria were isolated from the 119 samples in the study. Among them, 67 bacterial strains were isolated from 70 eyes of healthy dogs, and 65 bacterial strains were isolated from 49 eyes of dogs with keratitis. The prevalence of S. pseudintermedius, which was the most frequent bacterial isolate in both the groups, was 20.9% in the healthy group and 23.08% in the keratitis group. Most of the isolates of S. pseudintermedius were sensitive to rifampin (96.6%), oxacillin (100%), and neomycin (96.6%), and resistant to tetracycline (96.6%). Virulence factors such as lip (96.6%), hlgB (96.6%), and hlgA (96.6%) were found in most of the isolates, and 89.66% of isolates were classed as biofilm producers. In conclusion, S. pseudintermedius was the common bacterium in the conjunctivital sac of the healthy dogs and dogs with keratitis in Yangzhou, China, and the presence of virulence factors and biofilm-formation ability were high in the strains isolated from the dogs with keratitis.

Staphylococcus pseudintermedius: an undocumented, emerging pathogen in humans

The first infections of methicillin-resistant Staphylococcus pseudintermedius in humans were recorded in 2006, and is now becoming a concern because of its close similarities to human pathogens in the Staphylococcusintermedius group (SIG). These bacteria have all the properties which a multidrug-resistant Staphylococcus aureus possesses.

The literature was searched using the term “Staphylococcus pseudintermedius” in PubMed and other reference databases. The virulence factor and the pathogenicity are under investigation, but reports have suggested that this commensal of animals is transmitted easily via close contact to animals by owners, veterinarians and staff.

Resistance to beta-lactams (including methicillin) is a primary concern. Drug resistance to methicillin is a considerable problem in developing countries, as antibiotic use is not regulated. Studies from Europe have reported multidrug resistant isolates from clinical specimens. Although data on drug resistance and pathogenesis of S. pseudintermedius are not sufficient, it is extremely important to identify the pathogen correctly. Only then can its pathogenesis be studied during the course of disease and appropriate measures developed to prevent it becoming a global problem.

Geographical Variations in Virulence Factors and Antimicrobial Resistance Amongst Staphylococci Isolated From Dogs From the United Kingdom and Romania

The objective of this study was to compare virulence and resistance factors of mucosal and cutaneous staphylococci from dogs with pyoderma in the UK and Romania, two countries with different approaches to antimicrobial use in companion animals. Staphylococcal isolates (n = 166) identified to the species level as being Staphylococcus pseudintermedius or coagulase negative (CoNS) were analyzed for their antimicrobial resistance (AMR) profile and presence of resistance and virulence genes. Of the investigated isolates, 26 were methicillin-resistant S. pseudintermedius (MRSP), 89 were methicillin-susceptible S. pseudintermedius (MSSP) and 51 were coagulase negative staphylococci (CoNS). A significantly larger number of isolates originating from Romania were resistant to clindamycin, tetracycline, and chloramphenicol compared to the UK isolates (P < 0.05). Resistance to amoxicillin-clavulanic acid, gentamicin, and trimethoprim-sulphamethoxazole was more evident in UK isolates. Fusidic acid resistance was common in Staphylococcus spp. isolates from both countries. Most isolates carried virulence factors associated with siet (exfoliative toxin) and luk (leucocidin) genes. All MRSP UK isolates exhibited fusidic acid resistance genes whilst this was very rare in the MRSP isolates from Romania. The chlorhexidine resistance gene qacA/B was frequently identified in CoNS isolates from the UK (P < 0.001). The current study documented differences in antimicrobial resistance profiles of Staphylococcus spp. isolates from dogs in two geographical locations in Europe, which could reflect differences in antimicrobial prescribing patterns. The study also highlights the need for further studies and interventions on antimicrobial use, prescribing patterns and AMR surveillance in companion animals in Romania.

In Vitro Efficacy of Essential Oils from Melaleuca Alternifolia and Rosmarinus Officinalis, Manuka Honey-based Gel, and Propolis as Antibacterial Agents Against Canine Staphylococcus Pseudintermedius Strains

Essential oils (EOs) and honeybee products (e.g., honey and propolis) are natural mixtures of different volatile compounds that are frequently used in traditional medicine and for pathogen eradication. The aim of this study was to evaluate the antibacterial properties of tea tree (Melaleuca alternifolia) EO (TTEO), Rosmarinus officinalis EO (ROEO), manuka-based gel, and propolis against 23 strains of Staphylococcus pseudintermedius (SP) isolated from canine pyoderma. Antimicrobial resistance screening was assessed using a panel of nine antimicrobial agents coupled with a PCR approach. An aromatogram was done for both EOs, using the disk diffusion method. The minimum inhibitory concentration (MIC) was determined for all the compounds. Among the 23 SP strains, 14 (60.9%) were multidrug-resistant (MDR), 11 strains (47.8%) were methicillin-resistant (MRSP), and 9 (39.1%) were non-MDR. The mean diameter of the inhibition zone for Melaleuca and Rosmarinus were 24.5 ± 8.8 mm and 15.2 ± 8.9 mm, respectively, resulting as statistically different (p = 0.0006). MIC values of TTEO and ROEO were similar (7.6 ± 3.2% and 8.9 ± 2.1%, respectively) and no statistical significances were found. Honeybee products showed lower MIC compared to those of EOs, 0.22 ± 0.1% for Manuka and 0.8 ± 0.5% for propolis. These findings reveal a significant antibacterial effect for all the tested products.

Contamination of the urban environment with excrements of companion animals as an underestimated source of Staphylococcus species posing a threat to public health

The aim of the study was to assess the incidence, resistance, virulence, and genotypic characteristics of Staphylococcus spp. residing in the gastrointestinal tract of dogs and cats, as a group of animals causing potential contamination of the urban space. A high percentage of strains resistant to penicillin (58%), oxacillin (9%) and tetracycline (60%) were found. All isolates resistant to penicillin, kanamycin, or chloramphenicol carried genes responsible for individual resistance (blaZ, aph(3')-IIIa, and cat (pC194)/cat (pC223), respectively. The mecA gene was detected in 45% of the oxacillin-resistant Staphylococcus pseudintermedius strains. The amplification of DNA fragments surrounding rare restriction sites analysis demonstrated high heterogeneity of genotypic profiles correlating with phenotypic resistance profiles. Multilocus sequence typing analysis classified the methicillin-resistant S. pseudintermedius strains as ST71, ST890, and the totally new ST1047. The presence of a high level of resistance among Staphylococcus strains may suggest a potential risk of transfer of these bacteria between companion animals and humans.

Investigation on Antibiotic-Resistance, Biofilm Formation and Virulence Factors in Multi Drug Resistant and Non Multi Drug Resistant Staphylococcus pseudintermedius

Staphylococcus pseudintermedius is a commensal bacterium frequently isolated from canine skin and recognized as a zoonotic agent especially for dog-owners. This study focused on (a) the antibiotic-resistance phenotypes; (b) the ability to produce biofilm (slime); and (c) the dissemination of virulence factors in S. pseudintermedius strains. Seventy-three S. pseudintermedius strains were screened for antibiotic-resistance against 22 different molecules by means of Kirby-Bauer assay. The ability to produce biofilm was investigated using the microtiter plate assay (MtP) and the amplification of icaA and icaD genes. Virulence factors such as cytotoxins (lukI), enterotoxins (seC), and exfoliative toxins (siet, expA, and expB) were evaluated. The antibiotic-resistance profiles revealed 42/73 (57%) multi-drug resistant (MDR) strains and 31/73 (43%) not-MDR. All the MDR strains and 8/31 (27%) of not-MDR resulted in biofilm producers. Leukotoxin LukI was found in 70/73 (96%) of the isolates. Moreover, the enterotoxin gene seC was detected in 47/73 (64%) of the strains. All the isolates carried the siet gene, whereas expA and expB were found in 3/73 (4%) and 5/73 (7%), respectively. In conclusion, S. pseudintermedius should be considered a potential zoonotic and human agent able to carry different virulence determinants and capable of producing biofilm which facilitates horizontal gene transfer.

Genetic characterisation of methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius in pets and veterinary personnel in Iran: new insights into emerging methicillin-resistant S. pseudintermedius (MRSP)

OBJECTIVES

Methicillin-resistant staphylococci, including methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP), pose a threat to animal and human health worldwide. Veterinary staff and pets may play a role in the spread of resistant clones.

METHODS

A total of 125 samples from veterinary staff (n=50), dogs (n=49) and cats (n=26) were investigated. Obtained isolates were tested for the methicillin resistance gene mecA and were subjected to multiplex PCR to differentiate coagulase-positive species. Following SCCmec and spa typing, isolates were tested for the presence of various toxin and virulence genes and phenotypic resistance to common antimicrobials.

RESULTS

Overall, 4 MRSA were isolated from two veterinarians and two dogs and 19 MRSP were found in eleven dogs (12 isolates) and five cats (7 isolates). The MRSA isolates possessed sea (2) and eta (3) virulence genes and the MRSP isolates possessed sea (6), expA (15), expB (1) and siet (19) genes. SCCmec type II and three spa types (t186, t1816 and t10897) were identified in the MRSA isolates. Most of the MRSP isolates belonged to SCCmec types II (2 isolates) and V (10 isolates); however, the remaining 7 isolates were untypeable and contained class C1 mec. The majority of isolates were multidrug-resistant (MDR).

CONCLUSION

These findings show that pets and veterinarians could be potential sources of MDR-MRSA and MDR-MRSP in Iran. Taken together, these findings warrant future investigations on the epidemiology and public-health significance of MDR-MRSA and MDR-MRSP both in veterinarians and companion animals in Iran.

Skin infection caused by a novel strain of Staphylococcus pseudintermedius in a Siberian husky dog owner

Introduction.Staphylococcus pseudintermedius, an opportunistic pathogen of dogs and cats, is rarely reported to cause infection in humans. Here, we describe a case of severe skin infection caused by S. pseudintermedius, in a 47-year-old male, a dog owner; to the best of our knowledge, this is the first such case reported from Scotland.

Case presentation. The patient presented with a short history of a severe ecthyma-like lesion on his forehead, with smaller lesions on his abdomen and legs. Bacterial culture revealed Clostridium perfringens, thought to be colonizing the wound, and a Staphylococcus species, identified as S. pseudintermedius by matrix-assisted laser desorption/ionization-time of flight MS and confirmed by molecular methods using a PCR-RFLP approach. The patient was treated with flucloxacillin, penicillin V and Fucibet cream, and recovered fully. Zoonotic infection was considered likely; however, screening swabs from his dogs grew S. pseudintermedius of a different clonal type. Both patient and dog strains carried Staphylococcus intermedius exfoliative toxin and leucocidin I, closely related to Panton–Valentine leucocidin, possibly contributing to the severity of the infection. S pseudintermedius, although coagulase positive, is normally negative by rapid slide clumping and latex agglutination tests routinely used to identify Staphylococcus aureus. Hence, S. pseudintermedius may easily be misidentified as a coagulase-negative staphylococcus and considered insignificant.

Conclusion. This is, to the best of our knowledge, the first reported case of a human S. pseudintermedius infection in Scotland. Zoonotic transmission of S. pseudintermedius between pets and owners has been shown. However, in this case zoonosis could not be confirmed.

Diversity of species and antimicrobial resistance determinants of staphylococci in superficial waters in Spain

The objectives were to determine the presence and diversity of staphylococcal species in surface waters in La Rioja region (Spain), and to characterize recovered isolates. Staphylococci were detected in 42 of 47 evaluable samples, and 72 isolates were obtained, of which 13 were coagulase-positive (CoPS) and 59 were coagulase-negative (CoNS). Twelve CoPS were identified as S. aureus and typed as follows (number of strains): t002/t502/ST5 (four), t10668/ST425 (one), t10712//ST1643 (one), t843/ST130 (one), t10855/ST2461 (one), t3369/ST2657 (one), t1166/ST133 (one), t8083/ST2049 (one) and t045/ST2460 (one); and one as S. pseudintermedius ST147. Virulence genes tst, cna and lukS/F-I were detected, and one strain showed the immune evasion cluster type F. Regarding CoNS, 12 different species were recovered (number of strains): S. epidermidis (11), S. vitulinus (10), S. sciuri (nine), S. fleurettii (seven), S. lentus (six), S. simulans (five), S. xylosus (four), S. chromogenes (two), S. hominis (two), and S. equorum, S. succinus and S. warneri (one each). Fourteen CoNS isolates presented a multidrug resistance phenotype, with the following resistance genes: blaZ, mecA, fusB, fusC, erm(C), mph(C), erm(A), msr(A)/(B), mph(C), ant(4')-Ia, tet(K), tet(L), cat_pc194 and str The high diversity of staphylococcal species, as well as multiple resistance and virulence genes, highlights the importance of surface waters as a temporary reservoir and source of transmission.

Comparative RNA-seq-Based Transcriptome Analysis of the Virulence Characteristics of Methicillin-Resistant and -Susceptible Staphylococcus pseudintermedius Strains Isolated from Small Animals

Staphylococcus pseudintermedius is often associated with pyoderma, which can turn into a life-threatening disease. The dissemination of highly resistant isolates has occurred in the last 10 years and has challenged antimicrobial treatment of these infections considerably. We have compared the carriage of virulence genes and biofilm formation between methicillin-resistant and methicillin-susceptible S. pseudintermedius (MRSP and MSSP, respectively) isolates and their in vitro gene expression profiles by transcriptome sequencing (RNA-seq). Isolates were relatively unevenly distributed among the four agr groups, and agr type III predominated in MRSP. Five virulence genes were detected in all isolates. Only the spsO gene was significantly associated with MSSP isolates (P = 0.04). All isolates produced biofilm in brain heart infusion broth (BHIB)-4% NaCl. MSSP isolates produced more biofilm on BHIB and BHIB-1% glucose media than MRSP isolates (P = 0.03 and P = 0.02, respectively). Virulence genes encoding surface proteins and toxins (spsA, spsB, spsD, spsK, spsL, spsN, nucC, coa, and luk-I) and also prophage genes (encoding phage capsid protein, phage infection protein, two phage portal proteins, and a phage-like protein) were highly expressed in the MRSP isolate (compared with the MSSP isolate), suggesting they may play a role in the rapid and widespread dissemination of MRSP. This study indicates that MRSP may upregulate surface proteins, which may increase the adherence of MRSP isolates (especially sequence type 71 [ST71]) to corneocytes. MSSP isolates may have an increased ability to form biofilm under acidic circumstances, through upregulation of the entire arc operon. Complete understanding of S. pseudintermedius pathogenesis and host-pathogen signal interaction during infections is critical for the treatment and prevention of S. pseudintermedius infections.

A peptide factor secreted by Staphylococcus pseudintermedius exhibits properties of both bacteriocins and virulence factors

Staphylococcus pseudintermedius is a common commensal bacterium colonizing the skin and mucosal surfaces of household animals. However, it has recently emerged as a dangerous opportunistic pathogen, comparable to S. aureus for humans. The epidemiological situation is further complicated by the increasing number of methicillin-resistant S. pseudintermedius infections and evidence of gene transmission driving antibiotic resistance between staphylococci colonizing human and zoonotic hosts. In the present study, we describe a unique peptide, BacSp222, that possesses features characteristic of both bacteriocins and virulence factors. BacSp222 is secreted in high quantities by S. pseudintermedius strain 222 isolated from dog skin lesions. This linear, fifty-amino-acid highly cationic peptide is plasmid-encoded and does not exhibit significant sequence similarities to any other known peptides or proteins. BacSp222 kills gram-positive bacteria (at doses ranging from 0.1 to several micromol/l) but also demonstrates significant cytotoxic activities towards eukaryotic cells at slightly higher concentrations. Moreover, at nanomolar concentrations, the peptide also possesses modulatory properties, efficiently enhancing interferon gamma-induced nitric oxide release in murine macrophage-like cell lines. BacSp222 appears to be one of the first examples of multifunctional peptides that breaks the convention of splitting bacteriocins and virulence factors into two unrelated groups.

Staphylococcus pseudintermedius can be misdiagnosed as Staphylococcus aureus in humans with dog bite wounds

The purpose of this study was to investigate whether S. pseudintermedius is misdiagnosed as S. aureus by clinical laboratories when isolated from humans with dog bite wounds. In addition, we attempted to determine whether S. pseudintermedius isolates related to dog bite wounds share phenotypic and genotypic traits. S. pseudintermedius was identified by PCR targeting the nuc gene. Isolates were tested for antibiotic susceptibility using VetMIC GP-mo microdilution panels. The occurrence of genes encoding leukocidins, exfoliatins, pyrogenic toxin superantigens and enterotoxins was determined by PCR. The relatedness of S. pseudintermedius isolates was investigated using Multi Locus Sequence Typing (MLST). Out of 101 isolates defined as S. aureus by human clinical microbiology laboratories, 13 isolates were re-identified as S. pseudintermedius and one isolate was confirmed to carry the mecA gene, i.e. methicillin-resistant (MRSP). The MRSP isolate was also defined as multi-resistant. Two methicillin-susceptible S. pseudintermedius isolates were also multi-resistant and five were susceptible to all antibiotics tested. With the exception of three S. pseudintermedius isolates belonging to multi locus sequence type (MLST) 158, all the isolates belonged to unique STs. All isolates contained lukS/F-I, siet and se-int, and expA were identified in two isolates and expB and sec canine-sel in one isolate respectively. S. pseudintermedius is frequently misdiagnosed as S. aureus from humans with dog bite wounds showing that it can act as an opportunistic pathogen in humans. No common phenotypic and genotypic traits shared by the S. pseudintermedius isolates could be identified.

Characterisation of nasal Staphylococcus delphini and Staphylococcus pseudintermedius isolates from healthy donkeys in Tunisia

REASONS FOR PERFORMING STUDY

Staphylococcus intermedius group (SIG) bacteria can colonise the nares of some animals but are also emerging pathogens in humans and animals.

OBJECTIVES

To analyse SIG nasal carriage in healthy donkeys destined for food consumption in Tunisia and to characterise recovered isolates.

METHODS

Nasal swabs from 100 healthy donkeys were tested for SIG recovery, and isolates were identified by biochemical and molecular methods. Antimicrobial susceptibility of isolates was tested and detection of antimicrobial resistance and virulence genes was performed. Isolates were typed at the clonal level by multilocus sequence typing and SmaI pulsed-field gel electrophoresis.

RESULTS

Staphylococcus delphini and Staphylococcus pseudintermedius (included in SIG) were obtained in 19% and 2% of the tested samples, respectively, and one isolate per sample was characterised. All isolates were meticillin susceptible and mecA negative. Most S. delphini and S. pseudintermedius isolates showed susceptibility to all antimicrobials tested, with the exception of 2 isolates resistant to tetracycline (tet(M) gene) or fusidic acid. The following toxin genes were identified (percentage of isolates): lukS-I (100%), lukF-I (9.5%), siet (100%), se-int (90%), seccanine (19%) and expA (9.5%). Thirteen different pulsed-field gel electrophoresis profiles were identified among the 21 SIG isolates. Additionally, the following 9 different sequence types (STs) were detected by multilocus sequence typing, 6 of them new: ST219 (6 isolates), ST12 (5 isolates), ST220 (3 isolates), ST13, ST50, ST193, ST196, ST218 and ST221 (one isolate each).

CONCLUSIONS

Staphylococcus delphini and S. pseudintermedius are common nasal colonisers of donkeys, generally susceptible to the antimicrobials tested; nevertheless, these SIG isolates contain virulence genes, including the recently described exfoliative gene (expA) and several enterotoxin genes, with potential implications for public health. This is the first description of S. delphini in Tunisia. The Summary is available in Chinese - see Supporting information.

Cluster of infections caused by methicillin-resistant Staphylococcus pseudintermedius in humans in a tertiary hospital

The dog-associated Staphylococcus pseudintermedius is a rare pathogen in humans. Here we describe a cluster of infections caused by the methicillin-resistant S. pseudintermedius clone ST71-J-t02-II-III. It involved four elderly patients at a tertiary hospital. Three patients had wound infections, and the strain had a tendency to cause bullous skin lesions.

Antibiotic resistance and molecular characterization of ophthalmic Staphylococcus pseudintermedius isolates from dogs

The prevalence, virulence potential, and antibiotic resistance of ophthalmic Staphylococcus pseudintermedius (SP) isolated from dogs were examined. Sixty-seven Staphylococcus species were isolated from ophthalmic samples and surveyed for species-specific sequences in the Staphylococcus intermedius group (SIG) nuclease gene (SInuc), exfoliative toxin gene for SIG (siet), and antibiotic resistance genes (blaZ and mecA). PCR-restriction fragment length polymorphism analysis of the pta gene was also performed. Fifty isolates were identified as SIG strains, all of which were found to be SP. The blaZ gene was detected in 42 of the 50 SP strains and mecA gene was observed in 18 of the 50 SP strains. The 50 SP strains were most susceptible to amoxicillin/clavulanic acid (94%) and chlorampenicol (70%), and highly resistant to tetracycline (94%) and penicillin (92%). It was also found that 16 (88.9%) mecA-positive SP strains were resistant to oxacillin, tetracycline and penicillin. All mecA-positive SP were resistant to more than four of the eight tested antibiotics and therefore considered SP with multi-drug resistance (MDR). Our results indicate a high prevalence of antibiotic resistance genes in ophthalmic SP along with a close relationship between MDR SP strains and the mecA gene. Based on our findings, judicious administration of antibiotics to companion dogs is necessary.

Antimicrobial resistance, virulence genes, and genetic lineages of Staphylococcus pseudintermedius in healthy dogs in tunisia

Nasal swabs of 100 healthy dogs were obtained in 2011 in Tunisia and tested for Staphylococcus pseudintermedius recovery. Antimicrobial resistance profile and virulence gene content were determined. Multilocus-sequence-typing (MLST) and SmaI-pulsed-field gel electrophoresis (PFGE) were investigated. S. pseudintermedius was recovered in 55 of the 100 tested samples (55 %), and one isolate per sample was further studied. All 55 S. pseudintermedius isolates were susceptible to methicillin (MSSP) but showed resistance to the following antimicrobials (% resistant isolates/resistance gene): penicillin (56.4/blaZ), tetracycline (40/tetM), trimethoprim-sulfamethoxazole (23.7), fusidic acid (9), kanamycin (3.7/aph(3´)-Ia), erythromycin-clindamycin (1.8/erm(B)), streptomycin (1.8/ant(6)-Ia), chloramphenicol (1.8) and ciprofloxacin (1.8). The following toxin genes were identified (% of isolates): lukS/F-I (98.2), expA (5.5), se-int (98.2), sec canine (1.8), siet (100), sea (5.5), seb (3.6), sec (10.9), sed (54.5), sei (5.5), sej (29.1), sek (3.6), ser (9.1), and hlg v (38.2). Ten different sequence-types were detected among 11 representative MSSP isolates: ST20, ST44, ST69, ST70, ST78, ST100, ST108, ST160, ST161, and ST162, the last three ones revealing novel alleles or allele combinations. Eleven different PFGE-patterns were identified in these isolates. The nares of healthy dogs could be a reservoir of antimicrobial resistant and virulent MSSP, highlighting the presence of the recently described exfoliating gene expA and several enterotoxin genes.

Animal and human Staphylococcus aureus associated clonal lineages and high rate of Staphylococcus pseudintermedius novel lineages in Spanish kennel dogs: predominance of S. aureus ST398

Methicillin-susceptible Staphylococcus aureus (MSSA) and Staphylococcus pseudintermedius (MSSP) are gaining interest to track the evolution of emerging methicillin-resistant strains in animals and humans. We focused on the characterization of the methicillin-susceptible coagulase-positive staphylococci (MSCoPS) recovered from nasal samples of 98 healthy kennel-dogs. Isolates were typed by spa, agr, MLST and SmaI/ApaI-PFGE. Antimicrobial resistance and virulence profiles were investigated. Presence of the human-associated Immune-Evasion-Cluster (IEC) genes was analyzed in MSSA. Twenty-four MSSA, 16 MSSP and one MS Staphylococcus schleiferi subspecies coagulans were obtained. Thirteen spa-types and 12 sequence-types (STs) were detected among MSSA, with ST398 predominance (7/24, 29.2%). MSSA isolates were enclosed within 6 clonal complexes (no. of isolates): CC5 (8), CC398 (7), CC88 (4), CC45 (2), CC133 (1), and CC22 (1), and one singleton. High clonal diversity was observed among MSSP, and 14 STs (10 of them new) were detected. Twelve (50%) MSSA and 12 (75%) MSSP isolates showed resistance to at least one of the tested antimicrobials, with low MSSA penicillin resistance (5 isolates) and high MSSP tetracycline resistance (9 isolates). MSSA isolates ST398, ST133, ST1 and ST2329[new] were susceptible to all antimicrobials and were the only ones lacking the scn, chp and/or sak IEC genes. High diversity of enterotoxin genes was detected among non-ST398/ST133 MSSA isolates. MSSP showed a more homogeneous virulence genes profile. Our results give evidence that dogs can be S. aureus carriers of not only typical human associated lineages but also lineages commonly detected among other animal species. Continue surveillance on CoPS in dogs is required to unveil their role in the dissemination of clones adapted to other animal species.

High diversity of Staphylococcus aureus and Staphylococcus pseudintermedius lineages and toxigenic traits in healthy pet-owning household members. Underestimating normal household contact?

Forty-three unrelated pet-owning households were screened in Spain to study the Staphylococcus aureus and Staphylococcus pseudintermedius nasal carriage, their genetic lineages and virulence traits. Sixty-seven healthy owners and 66 healthy pets were investigated. Isolates characterization was performed and potential interspecies transmission was assessed. S. aureus was present in 51.2% of households studied while S. pseudintermedius in 30.2%. Twenty-eight owners (41.8%) carried S. aureus: one methicillin-resistant S. aureus (MRSA) [t5173-ST8-SCCmecIVa] and 27 methicillin-susceptible S. aureus (MSSA). Three owners (4.5%) were colonized by methicillin-susceptible S. pseudintermedius (MSSP). Fifteen pets (22.7%) carried S. pseudintermedius: two methicillin-resistant S. pseudintermedius (MRSP) [ST71-SCCmecII/III; ST92-SCCmecV] and 13 MSSP; in addition, 8 pets (12.1%) presented MSSA. High diversity of spa and sequence types (STs) was detected. Typical livestock-associated S. aureus lineages (CC398, CC9) were observed in humans and/or companion animals and hospital and/or community-acquired S. aureus lineages (CC45, CC121, CC5, CC8) were detected among pets. Almost 40% of S. pseudintermedius were multidrug-resistant. S. aureus isolates harboured a remarkable high number of virulence genes. The expA gene was detected in 3 S. pseudintermedius isolates. Identical strains from both owners and their pets were identified in 5 households (11.6%): (a) four MSSA (t073-ST45/CC45, t159-ST121/CC121, t209-ST109/CC9, t021-ST1654([new])/singleton) and (b) one multidrug-resistant MSSP (ST142([new])). Highly clonally diverse and toxigenic S. aureus and S. pseudintermedius are common colonizers of healthy humans and pets. The presence of these bacterial species, virulence genes, and interspecies transmission detected, points out to consider pet ownership as a risk factor to acquire, maintain and spread, potential pathogenic bacteria.

The in vitro activity of 15 antimicrobial agents against bacterial isolates from dogs

The in vitro activity of 15 antimicrobial agents against clinical isolates of Staphylococcus pseudintermedius, Staphylococcus aureus, Escherichia coli, Pasteurella spp. and Streptococcus canis from dogs was investigated. For Staphylococcus spp., the highest frequency of resistance was observed for penicillin, followed by ampicillin, tetracycline and chloramphenicol. The highest frequency of resistance in E. coli isolates was recorded for tetracycline and streptomycin. Pasteurella spp. and S. canis had the highest resistance rate for tetracycline and chloramphenicol. Most isolates showed full susceptibility to low-level resistance to colistin, florfenicol and fluoroquinolones. Further studies using larger number of isolates from both healthy and diseased dogs would provide a broader picture of antimicrobial resistance at a national level and promote prudent use of antimicrobial agents in companion animals.

Staphylococcus pseudintermedius in the dog: taxonomy, diagnostics, ecology, epidemiology and pathogenicity

The dog is the natural host of Staphylococcus pseudintermedius. Many research efforts are currently being undertaken to expand our knowledge and understanding of this important canine commensal and opportunistic pathogen. The objective of this review is to summarize the current knowledge of the species, including the latest research outcomes, with emphasis on taxonomy, diagnostics, ecology, epidemiology and pathogenicity. Despite the important taxonomic changes that have occurred over the past few years, the risk of misidentification in canine specimens is low and does not have serious consequences for clinical practice. Staphylococcus pseudintermedius carriage in the dog is more frequent and genetically heterogeneous compared with that of Staphylococcus aureus in man. It appears that these staphylococcal species have evolved separately through adaptation to their respective natural hosts and differ with regard to various aspects concerning ecology, population structure and evolution of antibiotic resistance. Further understanding of the ecology and epidemiology of S. pseudintermedius is hampered by the lack of a standard method for rapid and discriminatory typing and by the limited data available on longitudinal carriage and population structure of meticillin-susceptible strains. With regard to pathogenicity, it is only now that we are starting to explore the virulence potential of S. pseudintermedius based on genomic and proteomic approaches, and more research is needed to assess the importance of individual virulence factors and the possible existence of hypervirulent strains.

Determination of staphylococcal exotoxins, SCCmec types, and genetic relatedness of Staphylococcus intermedius group isolates from veterinary staff, companion animals, and hospital environments in Korea

The Staphylococcus (S.) intermedius group (SIG) has been a main research subject in recent years. S. pseudintermedius causes pyoderma and otitis in companion animals as well as foodborne diseases. To prevent SIG-associated infection and disease outbreaks, identification of both staphylococcal exotoxins and staphylococcal cassette chromosome mec (SCCmec) types among SIG isolates may be helpful. In this study, it was found that a single isolate (one out of 178 SIG isolates examined) harbored the canine enterotoxin SEC gene. However, the S. intermedius exfoliative toxin gene was found in 166 SIG isolates although the S. aureus-derived exfoliative toxin genes, such as eta, etb and etd, were not detected. SCCmec typing resulted in classifying one isolate as SCCmec type IV, 41 isolates as type V (including three S. intermedius isolates), and 10 isolates as non-classifiable. Genetic relatedness of all S. pseudintermedius isolates recovered from veterinary staff, companion animals, and hospital environments was determined by pulsed-field gel electrophoresis. Strains having the same band patterns were detected in S. pseudintermedius isolates collected at 13 and 18 months, suggesting possible colonization and/or expansion of a specific S. pseudintermedius strain in a veterinary hospital.

Review on methicillin-resistant Staphylococcus pseudintermedius

Staphylococcus pseudintermedius is an important opportunistic pathogen of companion animals, especially dogs. Since 2006 there has been a significant emergence of methicillin-resistant S. pseudintermedius (MRSP) mainly due to clonal spread. This article reviews research on MRSP with a focus on occurrence, methods used for identification, risk factors for colonization and infection, zoonotic potential and control options. Potential areas for future research are also discussed.

Prevalence and antimicrogram of Staphylococcus intermedius group isolates from veterinary staff, companion animals, and the environment in veterinary hospitals in Korea

The Staphylococcus intermedius bacterial group (SIG) includes 3 distinct genetically heterogenous species: S. intermedius, S. pseudintermedius, and S. delphini. This pathogen group is associated with many opportunistic skin and ear infections in companion animals. Human infections with S. intermedius and S. pseudintermedius isolates and the emergence of methicillin-resistant isolates have been recently reported, which emphasizes the importance of nationwide identification of SIG isolate prevalence and antibiotic resistance in veterinary clinics. In the present study, a total of 178 SIG isolates were obtained from veterinary staff (n  =  40), companion animals (n  =  115), and the local environment (n  =  23) in 8 Korean veterinary hospitals. Isolates were differentiated into 167 S. pseudintermedius (93.8%) and 11 S. intermedius (6.2%) isolates; S. delphini isolates were not identified. The most effective antibiotics against these isolates included amoxicillin-clavulanic acid, amikacin, nitrofloxacin, imipenem, and vancomycin; whereas ampicillin, penicillin, tetracycline, erythromycin, and trimethoprim-sulfamethoxazole were not effective. Surprisingly, the 128 SIG isolates (71.9%) displayed multiple drug resistance (MDR) against 3 or more antibiotic classes. Out of 52 SIG isolates carrying the methicillin-resistance gene (mecA), only 34 (65.4%) were oxacillin-resistant, and 49 (94.2%) methicillin-resistant SIG were multidrug resistant. This finding suggests the presence of greater numbers of MDR phenotypes than other isolates (P < 0.05).

Genetic relatedness of methicillin-resistant Staphylococcus pseudintermedius (MRSP) isolated from a dog and the dog owner

In the present study four methicillin-resistant Staphylococcus pseudintermedius (MRSP) strains isolated from a dog (n=3) and the anterior nares of the dog owner (n=1) were investigated by conventional and molecular methods. The species identity of the four S. pseudintermedius strains was confirmed by conventional methods, by PCR mediated amplification of S. intermedius/S. pseudintermedius specific segments of thermonuclease encoding gene nuc and by restriction fragment length polymorphism analysis of phosphoacetyltransferase encoding gene pta. Investigation of the four S. pseudintermedius for toxinogenic potential revealed that all four strains were positive for the exfoliative toxin encoding gene siet and the leukotoxin encoding genes lukS, lukF. The oxacillin and penicillin resistance of the four S. pseudintermedius strains could be determined by cultivation of the strains on oxacillin resistant screening agar base, ChromID MRSA Agar and Brilliance MRSA Agar and by multiplex PCR detecting the resistance genes mecA and blaZ. The genetic relatedness of the strains was studied by macrorestriction analysis of their chromosomal DNA using pulsed field gel electrophoresis (PFGE). According to PFGE all four S. pseudintermedius strains represent an identical bacterial clone indicating a cross transmission between the dog and the dog owner.

Prevalence of genes for enterotoxins, toxic shock syndrome toxin 1 and exfoliative toxin among clinical isolates of Staphylococcus pseudintermedius from canine origin

A total of 74 Staphylococcus pseudintermedius strains were isolated from the 99 clinical cases of canine pyoderma or chronic otitis in our veterinary teaching hospital during May 2006-February 2008. In this study, we examined the genetic distribution of staphylococcal pyogenic toxins such as staphylococcal enterotoxins A (sea), B (seb), C (sec), D (sed), E (see), and toxic shock syndrome toxin 1 (tst) as well as the previously characterized S. intermedius exfoliative toxin (siet) among those isolates. The polymerase chain reaction analyses with the toxin gene-specific primers revealed that 18 (24.3%) of 74 S. pseudintermedius isolates carried the sec genes, but none of the sea, seb, sed, see and tst genes. Further DNA sequencing analysis of the amplified sec genes revealed that they all belonged to the canine type C staphylococcal enterotoxin (SEC(canine) ) whose superantigenic activity has been demonstrated. In addition to the sec(canine) genes, our polymerase chain reaction results showed that all the 74 isolates carried the siet gene. Since both SEC(canine) and SIET toxins are known to be biologically active, it would be interesting to investigate how those toxins are involved in the pathogenesis of the canine diseases by S. pseudintermedius such as pyoderma or chronic otitis.

Widespread rapid emergence of a distinct methicillin- and multidrug-resistant Staphylococcus pseudintermedius (MRSP) genetic lineage in Europe

In order to gain a deeper insight into the phylogenetic background and diversity of methicillin-resistant S. pseudintermedius (MRSP) of animal origin, genetic relationships and clonal distribution among 146 European MRSP were examined using different molecular and phenotypical typing approaches. MRSP strains were derived from clinical microbiological specimens (mainly of small animal origin) sent in for diagnostic purposes from various veterinary facilities between 2005 and 2008. Pulsed-field gel electrophoresis (PFGE) of SmaI-macrorestriction fragments allowed differentiation of five PFGE-clusters that were subdivided into further distinct subtypes. Representatives of each PFGE subtype were analyzed by multilocus sequence typing (MLST) for assignment of sequence types (ST). With one exception (ST5), all these MRSP strains belonged to ST71. Furthermore, assessment of spa-typing results revealed that the majority of all strains harboured spa type t02. Further sporadically detected spa types t05 and t06 as well as two new types (t15 and t23), were found to be closely related to t02. According to PCR-based SCCmec-typing, SCCmecIII was the most prevalent type (n=138), and solely one non-typeable variant was identified in several strains (n=8). In addition, all strains were tested positive by PCR for the leukotoxin encoding operon LukI and the Staphylococcus intermedius-exfoliative toxin (SIET), respectively. Our cumulative data indicate a recent emergence of a certain multidrug-resistant MRSP-lineage (ST71) in central and southern European countries during the last few years.

Phenotypic and genotypic characteristics of methicillin/oxacillin-resistant Staphylococcus intermedius isolated from clinical specimens during routine veterinary microbiological examinations

Methicillin/oxacillin resistance of 10 S. intermedius strains was investigated by conventional and molecular methods. The strains tested had been isolated in Germany during routine veterinary microbiological examinations of specimens from a small animal clinic between May and September 2005. Epidemiological relationships of the strains were studied by macrorestriction analysis of their chromosomal DNA using pulsed field gel electrophoresis (PFGE). Species identity of the 10 S. intermedius strains was confirmed by conventional methods and by PCR mediated amplification of S. intermedius specific segments of thermonuclease encoding gene nuc. As controls, four methicillin/oxacillin resistant S. intermedius (MRSI) strains obtained from specimens sent by four veterinarians and three selected methicillin/oxacillin sensitive S. intermedius (MSSI), also obtained from the small animal clinic, were tested. The 10 strains, representing approximately 6% of all S. intermedius isolated from the clinic throughout the time period mentioned above, and the four MRSI obtained from veterinarians, were methicillin/oxacillin and penicillin resistant using disk diffusion tests and could be cultivated on oxacillin resistant screening agar base (ORSAB). Both resistances could be confirmed by multiplex PCR detecting the resistance genes mecA and blaZ. The three MSSI were methicillin/oxacillin sensitive in all tests. Epidemiological investigation by macrorestriction analysis of the chromosomal DNA of the strains by pulsed field gel electrophoresis revealed that all 10 MRSI strains obtained from the clinic and the four MRSI strains obtained from veterinarians, in contrast to the three MSSI strains, represent identical or closely related bacterial clones possibly indicating a cross-infection of the animals in the clinic and the distribution of a single MRSI clone in the pet population.