High occurrence of multi-antimicrobial resistance in Staphylococcus intermedius isolates from healthy and diseased dogs and domesticated pigeons

Staphylococcal species composition in the skin microbiota of domestic pigeons (Columba livia domestica)

Staphylococci are a natural component of the skin microbiota of many organisms, including humans and birds. As opportunistic pathogens, they can cause a variety of infections in humans. The close contact between domestic pigeons and their owners provide an opportunity for exchange of skin-associated bacteria. In this study, 41 healthy racing pigeons were tested. Staphylococci were detected on the skin of each bird (41/41, 100%). Isolates were identified at the species level using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The diversity of the Staphylococcus species was relatively high and coagulase-negative staphylococci (CoNS) were predominantly isolated. In total, ten different staphylococcal species were identified. S. lentus (19/41, 46.3%) was noted most frequently. The pigeon skin was also inhabited by S. xylosus (6/41, 14.6%), S. equorum (4/41, 9.8%), S. hyicus (3/41, 7.3%), S. intermedius (2/41, 4.9%), S. sciuri (2/41, 4.9%), S. vitulinus (2/41, 4.9%), S. lugdunensis (1/41, 2.4%), S. hominis (1/41, 2.4%), and S. auricularis (1/41, 2.4%). Our results indicate that domestic pigeons may carry pathogens with zoonotic potential. All strains were susceptible to 12 antibiotics (ciprofloxacin, clindamycin chloramphenicol, erythromycin, fosfomycin, gentamicin, levofloxacin, norfloxacin, rifampicin, tobramycin, trimethoprim/sulfamethoxazole, vancomycin) representing 8 different classes. None isolate displayed a multidrug-resistant phenotype. Resistance to tetracycline (6/41, 14.6%) and to penicillin (4/41, 9.7%) was shown. The mecA gene was not detected in the examined strains and no methicillin-resistant staphylococci were found on the skin of the healthy pigeons.

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.

Influence of hospital size on antimicrobial resistance and advantages of restricting antimicrobial use based on cumulative antibiograms in dogs with Staphylococcus pseudintermedius infections in Japan

Background

Antimicrobial resistance in Staphylococcuspseudintermedius (SP) and the prevalence of meticillin‐resistant SP (MRSP) is increasing in dogs worldwide.

Objectives

To evaluate the influence of hospital size on antimicrobial resistance of SP and whether restricted use of antimicrobials based on antibiograms could reduce the identification of antimicrobial resistance in SP from infected dogs.

Methods and materials

In Study 1, a total of 2,294 SP isolates from dogs with pyoderma (n = 1,858, 52 hospitals) or otitis externa (OE; n = 436, 44 hospitals) taken between 2017 and 2019 were analysed. Clinics were categorised into small, medium and large based on numbers of practicing veterinary surgeons. In Study 2, a cumulative antibiogram was constructed for 12 antimicrobials from one large veterinary clinic from 2017 to 2018. Referring to this antibiogram, the clinic introduced strict antimicrobial selection criteria to treat dogs with pyoderma and OE, starting in 2018.

Results

MRSP was identified in 981 dogs (42.8%). In large clinics, the isolation rate of MRSP was 51.1% (404 of 791), which was significantly higher (P < 0.01) than in small clinics with less than two veterinary practitioners (34.0%, 154 of 453). In the antibiogram study, the susceptibility rates of oxacillin (MPIPC, 61.5%), cefpodoxime (CPDX, 55.8%) and minocycline (MINO, 55.8%) were significantly higher in 2019 (n = 52) than in 2017 to 2018 (n = 54; MPIPC, 37.0%; CPDX, 33.3%; MINO, 20.4%; P < 0.05).

Conclusions and clinical relevance

Hospital size could affect the isolation rate of MRSP in dogs. Restricted use of antimicrobials for over a year based on cumulative antibiograms could reduce the resistance rate of multiple antimicrobials in SP isolated from dogs with pyoderma and OE.

Background – Antimicrobial resistance in Staphylococcuspseudintermedius (SP) and the prevalence of meticillin‐resistant SP (MRSP) is increasing in dogs worldwide. Objectives: To evaluate the influence of hospital size on antimicrobial resistance of SP and whether restricted use of antimicrobials based on antibiograms could reduce the identification of antimicrobial resistance in SP from infected dogs. Conclusions and clinical relevance – Hospital size could affect the isolation rate of MRSP in dogs. Restricted use of antimicrobials for over a year based on cumulative antibiograms could reduce the resistance rate of multiple antimicrobials in SP isolated from dogs with pyoderma and OE.

EFFECTIVENESS OF TOBRAMYCIN AND CIPROFLOXACIN AGAINST BACTERIAL ISOLATES IN CANINE OTITIS EXTERNA IN UBERABA, MINAS GERAIS

Abstract Canine otitis externa is a common and recurrent disease in domestic dogs. Although not being life threatening, it can result in the overuse of antibiotics, increased bacterial resistance and reduction of options for treatment. This study aimed to determine: the principal characteristics (age, race, and gender) of dogs affected by otitis externa; the most frequently bacteria identified as being associated with it and their antimicrobial resistance profiles. A total of 221 bacterial isolates were identified by morphological staining and biochemical processes and tested against eleven antibiotics. Among the 148 dogs diagnosed with otitis externa, 51.4% (76/148) were males and 48.6% (72/148) females. The cases were detected mainly in dogs with age above 7 years (54.7%; 81/148. Among the races examined, poodles were the most numerous (14.84%; 22/148). The most common bacteria found were: coagulase-negative Staphylococcus (StCN), 33.9% (75/221); coagulase-positive Staphylococcus (StCP), 19% (42/221); Proteus spp., 17.2% (38/221) and Pseudomonas aeruginosa, 9.5% (21/221). Simultaneous resistance to more than three classes of antimicrobials were most frequently detected in P. aeruginosa (61.9%; 13/21) and Proteus spp (39.47%; 15/38). According to data obtained from this study, two veterinary medications found to be most effective for topical treatment were tobramycin and ciprofloxacin.

Genetic characterization of coagulase-positive staphylococci isolated from healthy pigeons

Coagulase-positive staphylococci (CoPS) are opportunistic veterinary pathogens, of which Staphylococcus aureus, S. delphini and S. intermedius can be isolated from pigeons. The biochemical identification of S. delphini and S. intermedius isolates may be incorrect, because of their phenotypic similarity. The purpose of the present study was to isolate and identify CoPS from domestic and feral pigeons and to determine their genetic relatedness by PFGE. A total number of 31 isolates of CoPS were obtained, 15 were identified as S. delphini group B, six as S. aureus, four as S. delphini group A, three as S. intermedius and three as S. schleiferi subsp. coagulans. The results indicate that S. delphini group B is the predominant CoPS species among pigeons studied. PFGE restriction patterns of S. delphini group A and S. delphini group B form separate clusters, demonstrating their genetic heterogeneity. Indistinguishable or very similar PFGE patterns observed among S. delphini group B isolates from domestic and feral pigeons confirm the possibility of CoPS transmission between these birds.

Antimicrobial resistance in bacteria isolated from pigeons in Poland

The present study investigated the drug-resistance to the selected antibiotics in Escherichia coli, Salmonella typhimurium and beta-haemolytic coagulase-positive staphylococci isolated from pigeons bred in Poland. In the case of E. coli, tetracyclines and amoxicillin were least effective. In the staphylococci, the highest resistance was detected for oxytetracycline and quinolones and 5% were resistant to methicillin. The lowest drug-resistance was reported for Salmonella typhimurium.

Genetic relatedness, antimicrobial and biocide susceptibility comparative analysis of methicillin-resistant and -susceptible Staphylococcus pseudintermedius from Portugal

Forty methicillin-resistant and -susceptible Staphylococcus pseudintermedius (MRSP and MSSP, respectively) from colonization and infection in dogs and cats were characterized for clonality, antimicrobial, and biocide susceptibility. MSSP were genetically more diverse than MRSP by multi-locus sequence typing and pulsed-field gel electrophoresis. Three different spa types (t06, t02, t05) and two SCCmec types (II-III and V) were detected in the MRSP isolates. All MRSP and two MSSP strains were multidrug-resistant. Several antibiotic resistance genes (mecA, blaZ, tet(M), tet(K), aac(6')-Ie-aph(2')-Ia, aph(3')-III, ant(6)-Ia, sat4, erm(B), lnu(A), dfr(G), and catp(C221)) were identified by microarray and double mutations in the gyrA and grlA genes and a single mutation in the rpoB gene were detected by sequence analysis. No differences were detected between MSSP and MRSP in the chlorhexidine acetate (CHA) minimum inhibitory concentrations (MICs). However, two MSSP had elevated MIC to triclosan (TCL) and one to benzalkonium chloride and ethidium bromide. One MSSP isolate harboured a qacA gene, while in another a qacB gene was detected. None of the isolates harboured the sh-fabI gene. Three of the biocide products studied had high bactericidal activity (Otodine(®), Clorexyderm Spot Gel(®), Dermocanis Piocure-M(®)), while Skingel(®) failed to achieve a five log reduction in the bacterial counting. S. pseudintermedius have become a serious therapeutic challenge in particular if methicillin- resistance and/or multidrug-resistance are involved. Biocides, like CHA and TCL, seem to be clinically effective and safe topical therapeutic options.

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.

Risk factors associated with the antimicrobial resistance of staphylococci in canine pyoderma

This study reports the susceptibility to antimicrobial agents of staphylococci (n=105) isolated from dogs, and the factors associated with this resistance. The study animals were 23 healthy dogs (group A), 24 with first-time pyoderma (group B), and 27 with recurrent pyoderma that had undergone long-term antibiotic treatment (group C). Staphylococci were more commonly isolated from the pyoderma-affected than the healthy dogs (p<0.0001). Some 78% of the isolates were resistant to at least one antimicrobial agent. Resistance to amoxicillin-clavulanate, cephalosporins (OR 4.29, 95% CI [1.15, 16.3] respectively), enrofloxacin (OR 9.47, 95% CI [1.53, 58.5]) and ciprofloxacin (OR 79.7 95% CI [3.26, 1947.4]) was more common among group C isolates. Some 32% of all the isolates were multiresistant (MR) and 10.4% were methicillin-resistant (MRS). The probability of isolating MRS staphylococci in group C increased by a factor of four (95% CI [1.18, 17.9]) compared to A plus B. Multi-resistant (MR) isolates were obtained more commonly from urban than rural dogs (OR 3.79, 95% CI [1.09, 13.17]). All the MRS staphylococci encountered were obtained from urban dogs and more commonly from male dogs (p=0.07). This study shows that dogs bred in urban habitat, with a history of antibiotic therapy in the past year represents significant risk of being carriers of isolates resistant to methicillin (MRS) and other antimicrobials. These factors should be considered before applying an antimicrobial treatment in veterinary clinics.

Antimicrobial susceptibility and methicillin resistance in Staphylococcus pseudintermedius and Staphylococcus schleiferi subsp. coagulans isolated from dogs with pyoderma in Japan

To understand species distribution, trends of antimicrobial susceptibility and prevalence of methicillin resistance in canine staphylococci in Japan, 190 coagulase-positive staphylococci (CoPS) were isolated from dogs with pyoderma in 2 Japanese veterinary referral hospitals. Using a multiplex polymerase chain reaction (M-PCR) method, two CoPS species were identified: 170 Staphylococcus pseudintermedius (89.5%) and 20 S. schleiferi subsp. coagulans isolates (10.5%). In these isolates, susceptibility to 7 antimicrobial agents was determined. Overall, the levels of susceptibility to cefalexin (CEX), amoxicillin/clavulanic acid (CVA/AMPC), minocycline (MINO), ofloxacin (OFLX), norfloxacin (NFLX), lincomycin (LCM) and clindamycin (CLDM) in S. pseudintermedius isolates were 38.2, 52.4, 34.7, 31.2, 34.1, 1.2 and 11.2%, respectively. In S. schleiferi subsp. coagulans isolates, 55% demonstrated susceptibility to CEX, 80% to CVA/AMPC, 70% to MINO, 45% to OFLX or NFLX and 30% to CLDM. None of S. schleiferi subsp. coagulans isolates was susceptible to LCM. To determine the prevalence of methicillin-resistant strains, we used a PCR method, which enabled detection of the fragment of mecA gene in 66.5% (113 of 170) in S. pseudintermedius and 30.0% (6 of 20) in S. schleiferi subsp. coagulans isolates. The frequencies of susceptibility to CEX, CVA/AMPC, OFLX, NFLX and CLDM were significantly lower in methicillin-resistant CoPS than in methicillin-susceptible CoPS isolates. These data suggest a high level of methicillin resistance in staphylococci isolated from dogs with pyoderma in Japan.

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.

First report of multiresistant, mecA-positive Staphylococcus intermedius in Europe: 12 cases from a veterinary dermatology referral clinic in Germany

Resistance to cephalosporins and/or fluoroquinolones by Staphylococcus intermedius has remained low in Europe, with effective drugs generally available for systemic therapy in pets. However, multiresistant, mecA-positive S. intermedius isolated from dogs and cats is now emerging in Europe. Twelve S. intermedius isolates, highly resistant to at least five antimicrobial classes, were isolated from skin and ear infections in 11 dogs and a cat. The 12 isolates represented 23% of all S. intermedius submissions from one veterinary dermatology referral clinic in northern Germany to veterinary diagnostic laboratories during an 18-month period and resistance included cefalexin, methicillin and enrofloxacin. The animals had been referred to the clinic with recurrent superficial pyoderma, deep pyoderma, pododermatitis or chronic otitis, all unresponsive to systemic beta-lactam-antibiotics or fluoroquinolones. Infection resolved in 10 dogs and the cat on a combination of antimicrobial treatment and correction of underlying causes. Four dogs and a cat required systemic and topical therapy; in six dogs topical antimicrobial therapy alone was successful. Phenotypic and genotypic characteristics of the S. intermedius isolates were determined; species identification was confirmed by polymerase chain detection of thermonuclease genes (nuc) and the presence and expression of the gene conferring resistance to all beta-lactam antibiotics (mecA) were demonstrated in all; based on pulsed-field gel electrophoresis, six were indistinguishable, the others closely or possibly related. The emergence of multiresistant, mecA-positive S. intermedius in Europe is alarming. Zoonotic implications, awareness among veterinary laboratories and strategies for the use of antimicrobials in small animal practice need to be considered.