Identification and Antimicrobial Susceptibility of Bacteria and Yeasts Isolated from Healthy Dogs and Dogs with Otitis Externa

Prevalence and risk factors of Staphylococcus spp. carriage among dogs and their owners: A cross-sectional study

This study investigated colonization and association of staphylococci between healthy dogs and their owners. In a cross-sectional study, nasal carriage and antibiotic susceptibility of isolated staphylococci were determined for 119 dogs and 107 owners. Relatedness of the Staphylococcus isolates in dogs and their owners was investigated using antibiograms, toxin profiles, and genotyping by pulsed-field gel electrophoresis (PFGE), multilocus sequence type, and spa typing. Risk factors for carriage of methicillin-resistant staphylococci in dogs were also evaluated. Staphylococcus spp. were isolated from 65 (60.7%) owners and 44 (37.0%) dogs. The following species were isolated, listed in order of decreasing frequency: S. epidermidis, S. pseudintermedius, S. aureus, S. scheiferi subsp. coagulans, S. haemolyticus, S. sciuri, S. saprophyticus and S. warneri. S. pseudintermedius (65.9%) was the major isolate in dogs while S. epidermidis (81.5%) was the major type in owners. Among the isolates, 71.6% were methicillin resistant (MR) and 95.4% of the isolates demonstrated multi-drug resistance regardless of the origin. Only one dog-owner pair shared the same Staphylococcus spp. (S. pseudintermedius); however, the organisms were of different PFGE subtypes and exhibited different antibiotic resistance and toxin profiles while both isolates displayed same sequence type (ST365). While the dog-origin isolate showed spa type t02, the owner-origin isolate was negative to PCRs targeting spa gene sequence. Risk factor analysis showed that the presence of cohabitant animals was correlated with the nasal carriage of MR staphylococci in dogs. The cumulative data indicated that animal- and owner-origin staphylococci have various subtypes with high prevalence of MR; however, the bacteria are not shared between healthy dogs and their owners.

What is living on your dog's skin? Characterization of the canine cutaneous mycobiota and fungal dysbiosis in canine allergic dermatitis

To characterize the skin-associated fungal microbiota (mycobiota) in dogs, and to evaluate the influence of body site, individual dog or health status on the distribution of fungi, next-generation sequencing was performed targeting the internal transcribed spacer region. A total of 10 dogs with no history of skin disease were sampled at 10 distinct body sites consisting of haired and mucosal skin, and 8 dogs with diagnosed skin allergies were sampled at six body sites commonly affected by allergic disease. Analysis of similarities revealed that body site was not an influencing factor on membership or structure of fungal communities in healthy skin; however, the mucosal sites were significantly reduced in fungal richness. The mycobiota from body sites in healthy dogs tended to be similar within a dog, which was visualized in principle coordinates analysis (PCoA) by clustering of all sites from one dog separate from other dogs. The mycobiota of allergic skin was significantly less rich than that of healthy skin, and all sites sampled clustered by health status in PCoA. Interestingly, the most abundant fungi present on canine skin, across all body sites and health statuses, were Alternaria and Cladosporium—two of the most common fungal allergens in human environmental allergies.

The skin-associated fungal microbiota were characterized in healthy dogs and those with skin allergies using next-generation sequencing, and the authors identified significant influences of the dog and health status on the distribution and diversity of fungal communities.

Agar Diffusion Procedures for Susceptibility Testing of Malassezia pachydermatis: Evaluation of Mueller-Hinton Agar Plus 2 % Glucose and 0.5 µg/ml Methylene Blue as the Test Medium

Aim of this study was to verify whether Mueller-Hinton agar supplemented with 2 % glucose and methylene blue (MH-GM), which is used for disk diffusion susceptibility testing of Candida species by the Clinical and Laboratory Standards Institute, is suitable for testing Malassezia pachydermatis. A variant of the disk diffusion procedure utilizing a 9-mm tablet was used to test 31 isolates against clotrimazole and miconazole using MH-GM as test medium. The MH-GM agar optimally supported the growth of all M. pachydermatis isolates, provided that the yeast inoculum was prepared with a lipid source (Tween 40 and 80). Zone edges were frequently definite and clear, facilitating the measurement of zone size and minimizing subjectivity. The inhibition zones correlated with MIC values obtained in a broth dilution assay. The agar diffusion method with MH-GM as the test medium appears as a suitable procedure for testing the susceptibility of M. pachydermatis to CTZ and MCZ in clinical laboratories. This test format may allow processing a large number of isolates in epidemiological studies. This may in turn facilitate clarifying to what extent the problem "drug resistance" accounts for cases of treatment failure in dogs with Malassezia otitis and dermatitis.

Phenotypic and molecular characterization of antimicrobial resistance in Proteus mirabilis isolates from dogs

Large-scale monitoring of resistance to 14 antimicrobial agents was performed using 103 Proteus mirabilis strains isolated from dogs in Japan. Resistant strains were analysed to identify their resistance mechanisms. Rates of resistance to chloramphenicol, streptomycin, enrofloxacin, trimethoprim/sulfamethoxazole, kanamycin, ampicillin, ciprofloxacin, cephalothin, gentamicin, cefoxitin and cefotaxime were 20.4, 15.5, 12.6, 10.7, 9.7, 8.7, 5.8, 2.9, 2.9, 1.9 and 1.9%, respectively. No resistance to ceftazidime, aztreonam or imipenem was found. Class 1 and 2 integrases were detected in 2.9 and 11.7% of isolates, respectively. Class 1 integrons contained aadB or aadB-catB-like-blaOXA10-aadA1, whereas those of class 2 contained sat-aadA1, dhfr1-sat-aadA1 or none of the anticipated resistance genes. Of five distinct plasmid-mediated quinolone-resistance (PMQR) genes, only qnrD gene was detected in 1.9% of isolates. Quinolone-resistance determining regions (QRDRs) of gyrA and parC from 13 enrofloxacin-intermediate and -resistant isolates were sequenced. Seven strains had double mutations and three had single mutations. Three of nine ampicillin-resistant isolates harboured AmpC-type β-lactamases (i.e. blaCMY-2, blaCMY-4 and blaDHA-1). These results suggest that canine Proteus mirabilis deserves continued surveillance as an important reservoir of antimicrobial resistance determinants. This is the first report, to our knowledge, describing integrons, PMQRs and QRDR mutations in Proteus mirabilis isolates from companion animals.

In vitro amphotericin B susceptibility of Malassezia pachydermatis determined by the CLSI broth microdilution method and Etest using lipid-enriched media

We determined the in vitro amphotericin B susceptibility of 60 Malassezia pachydermatis isolates by the CLSI broth microdilution method and the Etest using lipid-enriched media. All isolates were susceptible at MICs of ≤ 1 μg/ml, confirming the high activity of amphotericin B against this yeast species. Overall, the essential agreement between the tested methods was high (80% and 96.7% after 48 h and 72 h, respectively), and all discrepancies were regarded as nonsubstantial.

Susceptibility variation of Malassezia pachydermatis to antifungal agents according to isolate source

Malassezia pachydermatis is associated with dermatomycoses and otomycosis in dogs and cats. This study compared the susceptibility of M. pachydermatis isolates from sick (G1) and healthy (G2) animals to azole and polyene antifungals using the M27-A3 protocol. Isolates from G1 animals were less sensitive to amphotericin B, nystatin, fluconazole, clotrimazole and miconazole.

Multilocus sequence analysis of Streptococcus canis confirms the zoonotic origin of human infections and reveals genetic exchange with Streptococcus dysgalactiae subsp. equisimilis

Streptococcus canis is an animal pathogen that occasionally causes human infections. Isolates recovered from infections of animals (n = 78, recovered from 2000 to 2010 in three European countries, mainly from house pets) and humans (n = 7, recovered from 2006 to 2010 in Portugal) were identified by phenotypic and genotypic methods and characterized by antimicrobial susceptibility testing, multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and emm typing. S. canis isolates presented considerable variability in biochemical profiles and 16S rRNA. Resistance to antimicrobial agents was low, with the most significant being tet(M)- and tet(O)-mediated tetracycline resistance. MLST analysis revealed a polyclonal structure of the S. canis population causing infections, where the same genetic lineages were found infecting house pets and humans and were disseminated in distinct geographic locations. Phylogenetic analysis indicated that S. canis was a divergent taxon of the sister species Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis and found evidence of acquisition of genetic material by S. canis from S. dysgalactiae subsp. equisimilis. PFGE confirmed the MLST findings, further strengthening the similarity between animal and human isolates. The presence of emm-like genes was restricted to a few isolates and correlated with some MLST-based genetic lineages, but none of the human isolates could be emm typed. Our data show that S. canis isolates recovered from house pets and humans constitute a single population and demonstrate that isolates belonging to the main genetic lineages identified have the ability to infect the human host, providing strong evidence for the zoonotic nature of S. canis infection.

Genetic diversity of Streptococcus equi subsp. zooepidemicus and doxycycline resistance in kennelled dogs

The genetic diversity and antibiotic resistance profiles of 38 Streptococcus equi subsp. zooepidemicus isolates were determined from a kennelled canine population during two outbreaks of hemorrhagic pneumonia (1999 to 2002 and 2007 to 2010). Analysis of the szp gene hypervariable region and the 16S-23S rRNA intergenic spacer region and multilocus sequence typing (MLST) indicated a predominant tetO-positive, doxycycline-resistant ST-10 strain during 1999 to 2002 and a predominant tetM-positive doxycycline-resistant ST-62 strain during 2007 to 2010.

Evaluation of the antifungal susceptibility of Malassezia pachydermatis to clotrimazole, miconazole and thiabendazole using a modified CLSI M27-A3 microdilution method

BACKGROUND

In this study, we evaluated the antifungal susceptibility of Malassezia pachydermatis to clotrimazole (CTZ), miconazole (MCZ), and thiabendazole (TBD), azole derivatives employed in aural formulations labeled for treatment of canine otitis.

METHODS

The procedure for in vitro testing was based on the indications of the Clinical and Laboratory Standards Institute (CLSI) M27-A3 microdilution method. A lipid-enriched medium was employed to enhance the yeast growth (Christensen's urea broth, with 0.1% Tween 80 and 0.5% Tween 40 as the lipid sources), while the inoculums size corresponded to approximately 1-5 × 10(5) yeast cells/mL. Microplates were incubated at 37°C and read 48 h after inoculation. Azole MICs inhibiting fungal growth were the lowest drug concentrations that showed an optical density of ≤ 50% of the (drug-free) growth control, as assessed by spectrophotometer (630 nm filter).

RESULTS

All isolates were inhibited by the three azoles, with different minimum inhibitory concentration (MIC) values. Most isolates were inhibited by drug concentrations of 2-8 (CTZ), 1-4 (MCZ), or 16-32 (TBD) μg/mL. These results are partially in agreement with the findings of previous studies, in which substantially higher/lower MICs were occasionally reported. This is likely because of the different methodologies employed. Such discrepancies may not apply to clinical situations, where the compounds are applied topically.

CONCLUSION AND CLINICAL IMPORTANCE

The concept that clinical failure is linked to increased MICs is debatable, because significantly higher concentrations (in most cases at least 1,000 × the MIC) of the antifungals that were included in our study are routinely used in formulated products.

Epidemiology and pathogenicity of zoonotic streptococci

Zoonotic infections caused by Streptococcus spp. have been neglected in spite of the fact that frequency and severity of outbreaks increased dramatically in recent years. This may be due to non-identification since respective species are often not considered in human medical diagnostic procedures. On the other hand, an expanding human population concomitant with an increasing demand for food and the increased number of companion animals favour conditions for host species adaptation of animal streptococci. This review aims to give an overview on streptococcal zoonoses with focus on epidemiology and pathogenicity of four major zoonotic species, Streptococcus canis, Streptococcus equi sub. zooepidemicus, Streptococcus iniae and Streptococcus suis.

Antibiotic resistance of canine Staphylococcus intermedius group (SIG)--practical implications

A total of 221 SIG strains were isolated from clinical samples of canine origin submitted to the Diagnostic Laboratory of the Division of Bacteriology and Molecular Biology at the Warsaw University of Life Sciences in Warsaw during the period 2006-2010. The aim of the study was to investigate the frequency of prevalence of methicillin-resistant SIG strains and to determine the MIC values of cephalotin, amoxicillin/clavulanic acid, ciprofloxacin, clindamycin, gentamicin, chloramphenicol, mupirocin for a collection of randomly selected 79 strains belonging to Staphylococcus intermedius group (SIG), including 23 mecA-positive and 56 mecA-negative strains. All isolates were identified as belonging to SIG based on their phenotypic properties and PCR amplification of S. intermedius-specific fragment of the 16S rRNA gene. The mecA gene was detected in 26 (12%) of 221 SIG strains. All tested mecA-negative SIG strains were susceptible to amoxicillin/clavulanic acid and cephalotin. One of the 56 mecA-negative SIG strains was resistant to ciprofloxacin, six (11%) to gentamicin. It was found that sixteen (29%) of 56 mecA-negative SIG strains were resistant to clindamycin. Most of the mecA-positive SIG strains were resistant to ciprofloxacin (96%), clindamycin (96%), and gentamicin (96%). Only one MRSIG strain was resistant to chloramphenicol. All examined mecA-positive SIG strains were found to be susceptible to mupirocin. Our results imply that staphylococcal multidrug resistance has become more prevalent, which could lead to difficulties in effective treatment. With some resistant strains the only therapeutic possibility are antimicrobial agents important in human medicine. New regulations for veterinary medicine concerning appropriate therapy of infections caused by multidrug-resistat staphylococci are needed.

Bacterial contamination of commercial ear cleaners following routine home use

Ear cleaning solutions are designed for repeated use, which raises the possibility for bacterial contamination leading to recurrent or persistent infectious otitis. The purpose of this study was to investigate the prevalence of bacterial contamination of commercial ear cleaners following routine home use in dogs and to describe the characteristics that are associated with contamination. Used ear cleaner bottles and information regarding their use were obtained from canine owners visiting veterinary dermatologists. Both the bottle applicator tips and the solution contents were cultured for aerobic bacteria. Bacterial contamination was present on 10% of the bottle tips and in 2% of the solutions. Isolated bacteria included Staphylococcus pseudintermedius, Bacillus spp., coagulase-negative Staphylococcus spp., Micrococcus spp. and Burkholderia cepacia. The contamination rate was significantly higher on the applicator tips than in the solutions (P = 0.0076). The applicator tip contamination rate was significantly higher in expired samples (17%) than in-date samples (4%; P = 0.0277). The bottle sizes were significantly larger for the samples with contaminated applicator tips compared with noncontaminated tips (P = 0.0455). The contamination rate was significantly higher when Tris-EDTA was an ingredient. Cleanliness of the bottle, contact with the ear canal and infection status of the ear at time of culture had no bearing on the contamination rate. In summary, with routine home use of commercial ear cleaners, pathogenic bacterial contamination is of minor concern. This concern may increase when expired products or larger bottles of ear cleaner are used and when Tris-EDTA is an ingredient.

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.

Antibacterial activity, chemical composition, and cytotoxicity of leaf's essential oil from brazilian pepper tree (schinus terebinthifolius, raddi)

The antibacterial potential of leaf’s essential oil (EO) from Brazilian pepper tree (Schinus terebinthifolius Raddi) against staphylococcal isolates from dogs with otitis externa was evaluated. The minimum inhibitory concentration of EO ranged from 78.1 to 1,250 μg/mL. The oil was analyzed by GC and GC/MS and cytotoxicity tests were carried out with laboratory animals.

Streptococcal infection in dogs: a retrospective study of 393 cases

Streptococcus spp are opportunistic pathogens that normally reside in the upper respiratory, intestinal, lower urinary, and genital tracts but can cause localized infection or septicemia in dogs of all ages. A retrospective study of streptococcal infection in 393 dogs was conducted to identify the species of Streptococcus isolated, determine demographics of affected dogs, and characterize the disease processes associated with infection. The major streptococcal species isolated were S canis (88 cases, 22.4%), S dysgalactiae ssp equisimilis (13, 3.3%), and S equi ssp zooepidemicus (4, 1.0%). Sex was not a risk factor (P > .30). Fetuses and neonates were more likely to have streptococcal infection than were other age groups (P < .001). Streptococcal septicemia was considered an important cause of abortion and neonatal death and was isolated from all samples submitted for aerobic culture from dogs in that age group. There was a seasonal trend, with dogs more likely to have streptococcal infection in summer months. In dogs for which a disease process was identified, streptococcal infection was associated with dermatitis (29 dogs), pneumonia (24 dogs), adult septicemia (13 dogs), and fetal/neonatal septicemia leading to abortion or neonatal death (16 dogs). Identification of other clinically significant bacterial, viral, fungal, and parasitic organisms was common (267 of 393 dogs, 68%), especially in dogs with dermatitis or pneumonia. Infection with Streptococcus spp should be considered in the differential diagnosis in cases of abortion, septicemia, dermatitis, and pneumonia in dogs. Clinical significance of isolation of streptococcal organisms should be interpreted in context of clinical signs and pathologic findings.

Antimicrobial activity of propolis extract against Staphylococcus coagulase positive and Malassezia pachydermatis of canine otitis

The aims of this study were to evaluate the antimicrobial potential of propolis extract by determining the minimum bactericidal concentration (MBC) for coagulase-positive Staphylococcus isolates (Staphylococcus aureus and Staphylococcus intermedius) and the minimum fungicidal concentration (MFC) for Malassezia pachydermatis isolates. The microorganisms were assayed using broth microdilution techniques. The MBC(90) was 21 mg mL(-1), and the MFC(90) was 5.3 mg mL(-1). The propolis extract was found to exhibit antimicrobial activity against both pathogens.

Evidence-based veterinary dermatology: a systematic review of interventions for Malassezia dermatitis in dogs

The aim of this systematic review was to evaluate the efficacy of antifungal treatments for Malassezia dermatitis in dogs and, when possible, to propose recommendation for or against their use. Electronic searches were carried out using PubMed MEDLINE(R), CABDirect and CONSULTANT database. The volumes of Advances in Veterinary Dermatology, the proceedings of ESVD/ECVD and AAVD/ACVD congresses were hand-searched for studies relevant to this review. All articles and book chapters discussing treatment of Malassezia dermatitis were scanned for additional citations. Lastly, a request was sent to the Vetderm Listserv to share recent clinical trials. The analysis evaluated study design, methodology quality, subject enrolment quality, type of interventions and outcome measures. The searches identified 35 articles, and 14 trials that fulfilled the following selection criteria: (i) in vivo clinical trials, (ii) dogs showing clinical lesions of Malassezia dermatitis and (iii) enrolment of at least five dogs. Among these, only eight studies fulfilled the following additional criterion: (iv) prospective in vivo clinical trials reporting clinical and mycological outcome measures. A total number of 14 different treatment protocols included four blinded, randomized and controlled trials (quality of evidence grade A), four controlled studies lacking blinding and/or randomization (grade B), five open uncontrolled trials (grade C) and one descriptive study (grade D). This systematic review allowed us to recommend, with good evidence, the use of only one topical treatment of Malassezia dermatitis (2% miconazole nitrate +2% chlorhexidine, twice a week for 3 weeks) and with fair evidence the use of two systemic treatments with azole derivatives (ketoconazole, 10 mg kg(-1) day(-1) and itraconazole, 5 mg kg(-1) day(-1) for 3 weeks).

Antimicrobial susceptibility of Staphylococcus intermedius and Staphylococcus schleiferi isolated from dogs

The susceptibility to 23 antimicrobial agents was determined in 114 isolates of Staphylococcus intermedius and eight isolates of Staphylococcus schleiferi of canine origin. Overall, 73% of S. intermedius isolates and 37.5% of S. schleiferi isolates were susceptible to all the 23 antimicrobials tested. The large majority of S. intermedius strains retained susceptibility to antimicrobials currently employed in treatment of pyoderma (cephalosporins, cotrimoxazole and association amoxicillin-clavulanic acid) as well as to those effective against staphylococci (fusidic acid, rifampicin and fluoroquinolones). Resistance in S. intermedius was observed mainly against macrolides, chloramphenicol and lincosamides, while S. schleiferi isolates retained susceptibility to all antimicrobials except three of six fluoroquinolones. Although, our results confirm susceptibility to antimicrobials currently employed in pyoderma treatment, the several different resistance patterns observed for S. intermedius emphasize the importance of antimicrobial susceptibility testing of canine staphylococci to choose the most appropriate treatment of infections and to allow the prudent use of antimicrobial drugs in companion animals.

Antimicrobial resistance in companion animals

Antimicrobial resistance (AMR) is an emerging problem in companion animals, because of difficult-to-treat infections, possible pressure to use antimicrobials that are important in human medicine, and potential zoonotic transmission. The extent and importance of AMR in companion animals are poorly understood, in part because of limited surveillance; however, it is clear that resistance is problematic in many pathogens and commensals, including staphylococci, enterococci, Escherichia coli and Salmonella.