Antimicrobial susceptibility of staphylococci isolated from otitis externa in dogs

Identification of bacteria associated with canine otitis externa based on 16S rDNA high-throughput sequencing

Bacteria are regarded as predisposing and perpetuating factors causing otitis externa (OE), whereas auricular anatomy is a predisposing factor. This study aims to investigate bacterial populations in the external auditory canals of healthy dogs and dogs with OE. Four categories of ear swabs included healthy erect-ear dogs, erect-ear dogs with OE, healthy pendulous-ear dogs and pendulous-ear dogs with OE. After bacterial DNA extraction, 16S rDNAs were amplified using specific primers within a V3/V4 region. Following DNA library construction, high-throughput sequencing was performed on MiSeq (Illumina). CLC Microbial Genomics Module was used to determine the rarefaction curve, bacterial classification, relative abundance, richness and diversity index. The results demonstrated that healthy dogs had higher bacterial richness and diversity than the dogs with OE. Comparable with culture-dependent methods described previously, this study revealed predominant Corynebacterium spp., Pseudomonas spp., Staphylococcus spp., and Proteus spp. in OE cases. Furthermore, high-throughput sequencing might disclose some potential emerging pathogens including Tissierella spp., Acinetobacter spp., and Achromobacter spp., which have not been reported in previous canine OE cases. Nevertheless, larger sample sizes are further required for an extensive evidence-based investigation.

Otitis Externa in Dogs: Distribution and Antimicrobial Susceptibility Patterns of Staphylococcus Spp. Isolates

The study aimed to investigate the Staphylococcus species from dogs with chronic otitis externa in Istanbul and to determine their antibiotic susceptibility patterns. Ear swab samples were collected from 100 dogs suspected of otitis externa admitted at the clinics of Istanbul University - Cerrahpaşa, Faculty of Veterinary Medicine. The dogs were of different age, gender, and breed. The bacterial isolation was performed by conventional methods. BD Phoenix Automated Microbiology System was used to confirm bacterial identification by conventional methods and to test antimicrobial susceptibility. Staphylococcus spp. were isolated from 36% of the samples collected from the dogs. S. pseudintermedius, S. aureus, S. epidermidis, S. hyicus and S. chromogenes were identified in 41.6%, 22.2%, 11.1%, 5.5%, and 5.5%. In Staphylococcus spp. isolates, enrofloxacin, penicillin, and ampicillin-sulbactam resistance was 8.3%, marbofloxacin resistance was 11.1%, doxycycline resistance was 16.6%, amoxicillin-clavulanic acid, erythromycin, and gentamicin resistance was 19.4%, tetracycline, clindamycin, and sulphonamide resistance was 25%. Methicillin resistance was not observed in any of the isolates. However, multiple drug resistance (MDR) was detected in 11 (30.5%) of 36 isolates. In conclusion, the early detection and antimicrobial sensitivity testing of Staphylococcus spp in dog otitis externa cases that do not respond to empiric therapy could be beneficial for appropriate antibiotic selection and treatment thus preventing MDR.

High rates of multidrug resistance in bacteria associated with small animal otitis: A study of cumulative microbiological culture and antimicrobial susceptibility

The etiology of otitis in dogs and cats is multifactorial and complex, involving bacterial and fungal pathogens. As empiric antimicrobial prescription is a common practice when treating such cases, antimicrobial resistance may represent a complicating factor. The aim of this study was to describe microbiological features and susceptibility profiles of pathogens associated with 142 cases of external otitis, comprising 138 dogs and 4 cats.. The specimens were processed to identify bacterial and fungal etiologies following standard microbiological methods. Antimicrobial susceptibility was determined in vitro against 15 antibiotics and 3 antifungals. Further, Staphylococcus spp. isolates were screened for the detection of β-lactamase enzymes using cefinase paper discs. Pseudomonas spp. and isolates from Enterobacteriaceae family were screened for colistin (Polymyxin E) resistance and for the mcr-1-mediated colistin resistance gene by PCR. The presence of mixed cultures of Enterobacteriaceae, Pseudomonas spp. and Staphylococcus spp., and co-infections with Malassezia spp., emphasizes the polymicrobial etiology of external otitis in small animals. Emerging rates of multidrug resistance observed in almost 50% of the isolates may alert for a near future of challenging veterinary cases unresponsive to first-line antimicrobials. In addition, these results highlight a potential public health concern of multidrug resistant bacteria, given the proximity of pets and their owners. This study addressed central aspects of external otitis, providing microbiologists and clinicians updated information on the etiology and treatment of challenging cases of multidrug resistant bacteria. It also provides priceless surveillance value in monitoring resistant bacteria in small animals.

Results of urinary bacterial cultures and antibiotic susceptibility testing of dogs and cats in the UK

Objectives

Bacterial urinary tract infections are a common diagnosis in small animal practice and antibiotics are often administered empirically. The aim of this study was to investigate the aetiology and antibiotic resistance of uropathogens in dogs and cats in the UK.

Materials and Methods

Retrospective study of uroculture and antibiotic susceptibility testing results (n=808) by disk diffusion processed at a veterinary pathology laboratory between 2011 and 2012.

Results

Significant bacteriuria was detected in 18.4% of samples from dogs and 10.0% from cats, most of which (>90%) yielded a single organism. Escherichia coli was the most prevalent bacterial species (54.7% and 55.6% of feline and canine isolates, respectively) followed by Proteus mirabilis in dog samples (22.7%) and Enterococcus spp. in cat samples (23.2%). Approximately a third of E. coli isolates were resistant to ampicillin but resistance was much lower among Enterococcus spp. and P. mirabilis. Resistance to amoxicillin‐clavulanic acid also seemed to be emerging, particularly in E. coli (almost 20% resistant). In contrast, resistance to trimethoprim‐sulfamethoxazole for uropathogens remained <13% except for P. mirabilis (19.4%). Overall, fluoroquinolones showed the best in vitro activity (resistance mostly below 10% for enrofloxacin and marbofloxacin).

Clinical Significance

Our results provide evidence of the emergence of resistance to antibiotics commonly used to treat bacterial urinary tract infections. Continued monitoring of the patterns of antibiotic resistance in uropathogens is needed to assess the adequacy of recommendations on the empiric therapy of these infections.

Collaborative Care Improves Treatment Outcomes for Dogs with Chronic Otitis Externa: A Collaborative Care Coalition Study

The purpose of this retrospective study was to compare outcome measures in dogs treated by a primary care veterinarian (pcDVM) before referral and after seeking collaboration with a board-certified veterinary dermatologist (BCVD) for cases of severe recurrent chronic otitis externa. Medical records of 65 client-owned dogs were retrospectively reviewed, and data were obtained regarding treatment history, referral timeframe, recurrence rate, clinical signs, and resolution of signs. The median number of otitis recurrences while under the care of the pcDVM was 4 (range 1-40) versus collaborative BCVD care of 2 (P < .01). There was a longer median time to otitis recurrence with collaborative care (171 days) compared with dogs managed by the pcDVM before referral (21 days; P > .01). Proliferative changes in the ear canals improved in 41/45 (91%) of cases under BCVD care compared with 6/45 (13%) under care by the pcDVM (P < .01). Dogs with chronic otitis had better long-term outcomes when collaboration with a BCVD was pursued within 6 mo of treatment. Referral or consultation with a BCVD should be considered for cases of chronic canine otitis that are persistent or quickly recurrent (20-30 days) over a 6 mo period.

Frequency, Distribution, and Antimicrobial Resistance of Coagulase-Negative Staphylococci Isolated from Clinical Samples in Dogs and Cats

This study aimed to investigate the frequency, distribution, and antimicrobial resistance of coagulase-negative staphylococci (CoNS) obtained from clinical samples from dogs and cats and to classify any methicillin-resistant CoNS (MRCoNS). The samples were collected in 2017-2018, and species identification and antimicrobial susceptibility testing were routinely performed using the Vitek2 system. Among 1,056 staphylococci, 185 CoNS (17.5%) were obtained and included 18 species from dogs (n = 116) and 14 species from cats (n = 69). The predominant species were Staphylococcus chromogenes (31.4%), Staphylococcus hominis ssp. hominis (16.2%), Staphylococcus warneri (10.8%), and Staphylococcus epidermidis (8.1%). The primary isolation sites were the skin and urinary tract. High levels of resistance to β-lactams (65.4%), tetracycline (44.3%), clindamycin (36.8%), and erythromycin (30.8%) were observed. Twenty-five MRCoNS (13.4%), mainly Staphylococcus haemolyticus (n = 8), S. epidermidis (n = 6), and S. hominis ssp. hominis (n = 5), were identified. SCCmec type V (n = 8) was the most common type, followed by SCCmec type IV (n = 6) and SCCmec type III (n = 2), whereas nontypable SCCmec were classified into nine MRCoNS. Some CoNS have been recorded in humans, and these might be transferred to and cause subsequent infections in humans. Moreover, the diversity of SCCmec types and resistant strains suggested that they may serve as a reservoir of resistance genes among staphylococci.

Effect of an anti-inflammatory pomegranate otic treatment on the clinical evolution and microbiota profile of dogs with otitis externa

BACKGROUND

Canine otitis externa (OE) is a common disease characterised by inflammation of the epithelial tissue of the external ear canal. Secondary infections are frequent, and Malassezia pachydermatis and Staphylococcus pseudintermedius are routinely isolated and treated with antifungal and antibiotic compounds.

HYPOTHESIS/OBJECTIVES

To analyse the otitis ear microbiome before and after a treatment with prednisolone plus pomegranate or antimicrobial drugs ANIMALS: 15 dogs with nonpurulent OE.

METHODS AND MATERIALS

A 30 day, double-blinded, multicentre, randomized and controlled parallel-group (1:1) trial was conducted in 15 dogs with nonpurulent OE, following two different topical treatments (prednisolone plus pomegranate versus prednisolone plus antibiotic and antifungal drugs). On days (D)0, D15 and D30, serum and skin otic samples were collected, and clinical examination and microbiome analysis (bacteria and fungi) were performed. Results were compared with validated otitis clinical scores to assess the effectiveness of both treatments.

RESULTS

Nine bacterial and four fungal families were detected during the three time-points tested. An increase in fungal diversity (Shannon index) and composition was the most significant change observed after both treatments. At treatment D15 and D30, the reduction in clinical signs was statistically significant in both treatment groups (P ≤ 0.05). Prednisolone plus pomegranate cleanser treatment was able to control the clinical signs of otitis as well as the bacterial and fungal overgrowth.

CONCLUSIONS AND CLINICAL IMPORTANCE

Mild otitis cases associated with microbial overgrowth may be managed with topical antiseptic and anti-inflammatory agents without the need for antibiotic and/or antifungal compounds.

In vitro antimicrobial photodynamic therapy using tetra-cationic porphyrins against multidrug-resistant bacteria isolated from canine otitis

Antimicrobial-resistant bacteria have been frequently isolated from canine otitis. Photodynamic therapy using porphyrins as photosensitizing molecules is an alternative therapy against microorganisms in localized infections. Therefore, we evaluated the antibacterial activity of two tetra-cationic porphyrins (H₂TMeP and ZnTMeP) against gram-positive and -negative bacteria isolated from canine otitis, as well as its putative action mechanism. For this, two gram-positive and two gram-negative bacteria frequently detected in cases of canine otitis (coagulase-positive and -negative staphylococci [CPS and CNS], Pseudomonas aeruginosa, and Proteus mirabilis) were used in antibacterial activity assays. Each porphyrin at a non-cytotoxic dose was incubated with a fixed concentration of each bacterium and exposed to white-light irradiation for 0, 30, 60, and 90 min. Clinical isolates of CPS and CNS were photo-inactivated after 30 min of white-light exposure by both porphyrins (p < 0.05). Gram-negative bacteria were also photo-inactivated after 30 min (p < 0.05), reaching complete inactivation after 60 and 90 min of white-light irradiation by H₂TMeP and ZnTMeP, respectively. Antibacterial assays using standard bacterial strains (ATCCs) demonstrated similar results to those obtained with clinical isolates, except for P. aeruginosa, which was completely inactivated by ZnTMeP at 60 min, and the absence of a significant reduction in P. mirabilis concentration when irradiated for 30 min. Similar assays were conducted using reactive oxygen species scavengers showing that the putative mechanism for bacterial inactivation is through the production of singlet oxygen species. These results indicated that H₂TMeP and ZnTMeP tetra-cationic porphyrins were effective against bacteria isolated from canine otitis.

Microbiological and antibacterial resistance profile in canine otitis externa – a comparative analysis

The aim of the present study was to compare the prevalence of microbial agents involved in canine otitis externa and their sensitivity to antibacterial drugs in two periods: 2007–2011 and 2013–2017. For 2013–2017, coagulase-positive staphylococci were the dominating bacterial species (186 isolates), followed by Pseudomonas aeruginosa (82 strains). The rate of isolated yeasts (mainly Malassezia pachydermatis) was substantially high (152 isolates). Compared to the earlier period (2007–2011) a tendency to more frequent occurrence of co-infections was noted – 61.7% and more than 80% of co-infections involved yeasts. Antibacterial resistance patterns showed a clear trend to increased resistance of coagulase-positive staphylococci and β-haemolytic streptococci to amoxicillin/clavulanic acid (42% and 50% respectively) and gentamicin (29%, 40%). Increased resistance of P. aeruginosa was established to gentamicin (16%) and amikacin (18%). The prevalence of pseudomonads resistant to enrofloxacin was lower (27%).

Temporal trends and predictors of antimicrobial resistance among Staphylococcus spp. isolated from canine specimens submitted to a diagnostic laboratory

Background

Resistance to commonly used antimicrobials is a growing concern in both human and veterinary medicine. Understanding the temporal changes in the burden of the problem and identifying its determinants is important for guiding control efforts. Therefore, the objective of this study was to investigate temporal patterns and predictors of antimicrobial resistance among Staphylococcus spp. isolated from canine specimens submitted to the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) between 1993 and 2009.

Methods

Retrospective data of 4,972 Staphylococcus isolates assessed for antimicrobial susceptibility using the disk diffusion method at the UKVDL between 1993 and 2009 were included in the study. Temporal trends were assessed for each antimicrobial using the Cochran-Armitage trend test. Logistic regression models were used to investigate predictors of antimicrobial resistance (AMR) and multidrug resistance (MDR).

Results

A total of 68.2% (3,388/4,972) Staphylococcus isolates were S. intermedius group (SIG), 18.2% (907/4,972) were coagulase-negative staphylococci (CoNS), 7.6% (375/4,972) were S. aureus, 5.8% (290/4,972) were S. hyicus, and S. schleiferi subsp. coagulans comprised 0.2% (12/4,972) of the isolates. The overall percentage of AMR and MDR were 77.2% and 25.6%, respectively. The highest levels of AMR were seen in CoNS (81.3%; 737/907), S. aureus (80.5%; 302/375), and SIG (77.6%; 2,629/3388). The lowest levels of AMR were observed in S. hyicus (57.9%; 168/290) and S. schleiferi subsp. coagulans (33.3%; 4/12). Overall, AMR and MDR showed significant (p<0.001) decreasing temporal trends. Significant temporal trends (both increasing and decreasing) were observed among 12 of the 16 antimicrobials covering 6 of the 9 drug classes assessed. Thus, significant increasing temporal trends in resistance were observed to β-lactams (p<0.001) (oxacillin, amoxicillin-clavulanate, cephalothin, and penicillin (p = 0.024)), aminoglycosides (p<0.001) (gentamicin, and neomycin), bacitracin (p<0.001), and enrofloxacin (p<0.001). In contrast, sulfonamide (p<0.001) (sulfadiazin) and tetracycline (p = 0.010) resistant isolates showed significant decreasing temporal trends in AMR. Staphylococcus spp., geographic region, and specimen source were significant predictors of both AMR and MDR.

Conclusions

Although not unexpected nor alarming, the high levels of AMR to a number of antimicrobial agents and the increasing temporal trends are concerning. Therefore, continued monitoring of AMR among Staphylococcus spp. is warranted. Future studies will need to identify local factors responsible for the observed geographic differences in risk of both AMR and MDR.

In vitro and in vivo efficacy of tea tree essential oil for bacterial and yeast ear infections in dogs

ABSTRACT: Otitis externa is a common complaint in dogs. Bacteria and yeasts are commonly involved and may perpetuate inflammatory reactions inside the ear canal. Otoscopy, cytological examination of secretion and microbiological culture embody forms of diagnosis. Cytology also has great use in accessing treatment evolution. Therapy usually consists of cleaning ear canals and subsequent use of antibiotics or antifungal products. As some of them may cause hypersensitivity and even ototoxicity, searching for new pharmacological bases is currently necessary and justifies this study, which aimed to evaluate in vitro and in vivo efficacy of tea tree essential oil for bacterial and yeast ear infections in dogs. Twenty-eight dogs from a particular shelter in Cuiabá (Mato Grosso, Brazil), presenting clinical signs of otitis externa, were enrolled in this clinical trial. In all of them, clinical and cytological evaluations, as well as culture and susceptibility testing of the affected ears were carried out. From each dog, one ear was treated with 5% tea tree essential oil lotion and the other with standard otic formulation, according to the type of infection (bacterial, yeast or both). In vitro susceptibility testings of all ear cultures, to the same drugs used in treatment, were also carried out. Culture results showed 62.5% bacterial and fungal infection, 33.9% bacterial infection and 3.6% fungal infection, from the 56 ear samples collected. The most common microorganisms isolated were Staphylococcus intermedius, Staphylococcus aureus, Proteus mirabilis and Malassezia pachydermatis. Gram-positive bacteria were susceptible to gentamycin in 60.5% and resistant in 16.3% of the samples. Five percent tea tree essential oil formulation produced a 5mm clear zone of inhibition around the disks in one of the 63 samples evaluated. Pure (100%) tea tree essential oil formulation produced a 10mm clear zone of inhibition around the disks in four of the 63 samples evaluated, a 9mm zone in three samples, an 8mm zone in 16 samples, a 7mm zone in seven samples, a 6mm zone in two samples and there was no clear zone in 31 samples. Inhibition zones were produced by strains of Staphylococcus intermedius, Staphylococcus hyicus, Corynebacterium sp., Proteus mirabilis and Enterobacter sp. tea tree essential oil ear solution significantly induced remission of clinical signs both in bacterial and yeast ear infections. It also reduced as much Malassezia pachydermatis ear infection as the nystatin solution used in this study, while gentamycin solution showed better antibacterial effect. More studies should be conducted to evaluate in vitro diffusion properties of tea tree essential oil. Good antimicrobial spectrum and the absence of adverse reactions confirm the importance of developing a tea tree formulation as an alternative therapy for ear infections in dogs.

Patterns and predictors of antimicrobial resistance among Staphylococcus spp. from canine clinical cases presented at a veterinary academic hospital in South Africa

BACKGROUND

Antimicrobial resistance in staphylococci, often associated with treatment failure, is increasingly reported in veterinary medicine. The aim of this study was to investigate patterns and predictors of antimicrobial resistance among Staphylococcus spp. isolates from canine samples submitted to the bacteriology laboratory at the University of Pretoria academic veterinary hospital between 2007 and 2012. Retrospective data of 334 Staphylococcus isolates were used to calculate the proportion of samples resistant to 15 antimicrobial agents. The Cochran-Armitage trend test was used to investigate temporal trends and logistic regression models were used to investigate predictors of antimicrobial resistance in Staphylococcus aureus and Staphylococcus pseudintermedius.

RESULTS

Results show that 98.2% (55/56) of the S. aureus isolates were resistant to at least one drug while 42.9% were multidrug resistant. Seventy-seven percent (214/278) of the S. pseudintermedius isolates were resistant to at least one drug and 25.9% (72/278) were multidrug resistant. Resistance to lincospectin was more common among S. aureus (64.3%) than S. pseudintermedius (38.9%). Similarly, resistance to clindamycin was higher in S. aureus (51.8%) than S. pseudintermedius (31.7%) isolates. There was a significant (p = 0.005) increase in S. aureus resistance to enrofloxacin over the study period. Similarly, S. pseudintermedius exhibited significant increasing temporal trend in resistance to trimethoprim-sulphamethoxazole (p = 0.004), clindamycin (p = 0.022) and orbifloxacin (p = 0.042). However, there was a significant decreasing temporal trend in the proportion of isolates resistant to doxycycline (p = 0.041), tylosin (p = 0.008), kanamycin (p = 0.017) and amoxicillin/clavulanic acid (p = 0.032).

CONCLUSIONS

High levels of multidrug resistance and the increasing levels of resistance to sulphonamides, lincosamides and fluoroquinolones among Staphylococcus spp. isolates in this study are concerning. Future studies will need to investigate local drivers of antimicrobial resistance to better guide control efforts to address the problem.

Burden and predictors of Staphylococcus aureus and S. pseudintermedius infections among dogs presented at an academic veterinary hospital in South Africa (2007-2012)

Background

Staphylococci are commensals of the mucosal surface and skin of humans and animals, but have been implicated in infections such as otitis externa, pyoderma, urinary tract infections and post-surgical complications. Laboratory records provide useful information to help investigate these infections. Therefore, the objective of this study was to investigate the burdens of these infections and use multinomial regression to examine the associations between various Staphylococcus infections and demographic and temporal factors among dogs admitted to an academic veterinary hospital in South Africa.

Methods

Records of 1,497 clinical canine samples submitted to the bacteriology laboratory at a veterinary academic hospital between 2007 and 2012 were included in this study. Proportions of staphylococcal positive samples were calculated, and a multinomial logistic regression model was used to identify predictors of staphylococcal infections.

Results

Twenty-seven percent of the samples tested positive for Staphylococcus spp. The species of Staphylococcus identified were S. pseudintermedius (19.0%), S. aureus (3.8%), S. epidermidis (0.7%) and S. felis (0.1%). The remaining 2.87% consisted of unspeciated Staphylococcus. Distribution of the species by age of dog showed that S. pseudintermedius was the most common (25.6%) in dogs aged 2–4 years while S. aureus was most frequent (6.3%) in dogs aged 5–6 years. S. pseudintermedius (34.1%) and S. aureus (35.1%) were the most frequently isolated species from skin samples. The results of the multivariable multinomial logistic regression model identified specimen, year and age of the dog as significant predictors of the risk of infection with Staphylococcus. There was a significant temporal increase (RRR = 1.17; 95% CI [1.06–1.29]) in the likelihood of a dog testing positive for S. pseudintermedius compared to testing negative. Dogs ≤ 8 years of age were significantly more likely to test positive for S. aureus than those >8 years of age. Similarly, dogs between 2–8 years of age were significantly more likely to test positive for S. pseudintermedius than those >8 years of age. In addition, dogs 2–4 years of age (RRR = 1.83; 1.09–3.06) were significantly more likely to test positive for S. pseudintermedius compared to those <2 years of age. The risk of infection with S. pseudintermedius or S. aureus was significantly higher in ear canal and skin specimens compared to other specimens.

Conclusions

The findings suggest that S. pseudintermedius and S. aureus were the most commonly isolated species from dogs presented at the study hospital. Age of the dog and the location of infection were significant predictors of infection with both Staphylococcus species investigated. Significant increasing temporal trend was observed for S. pseudintermedius but not S. aureus. This information is useful for guiding clinical decisions as well as future research.

In vitro antimicrobial activity of the organic extract of Cladonia substellata Vainio and usnic acid against Staphylococcus spp. obtained from cats and dogs

ABSTRACT: Cladonia substellata Vainio is a lichen found in different regions of the world, including the Northeast of Brazil. It contains several secondary metabolites with biological activity, including usnic acid, which has exhibited a wide range of biological activities. The aim of this study was to evaluate the in vitro antimicrobial activity of the organic extract of C. substellata and purified usnic acid. Initially, Staphylococcus spp., derived from samples of skin and ears of dogs and cats with suspected pyoderma and otitis, were isolated and analyzed. In antimicrobial susceptibility testing against Staphylococcus spp., 77% (105/136) of the isolates were resistant to the antimicrobials tested. In the assessment of biofilm production, 83% (113/136) were classified as producing biofilm. In genetic characterization, 32% (44/136) were positive for blaZ, no isolate (0/136) was positive for the mecA gene, and 2% (3/136) were positive for the icaD gene. The in vitro antimicrobial activity of the organic extract of C. substellata and purified usnic acid against Staphylococcus spp. ranged from 0.25mg/mL to 0.0019mg/mL, inhibiting bacterial growth at low concentrations. The substances were more effective against biofilm-producing bacteria (0.65mg/mL-0.42mg/mL) when compared to non-biofilm producing bacteria (2.52mg/mL-2.71mg/mL). Usnic acid and the organic extract of C. substellata can be effective in the treatment of pyoderma and otitis in dogs and cats caused by Staphylococcus spp.

Carriage of Staphylococcus species in the veterinary visiting dog population in mainland UK: molecular characterisation of resistance and virulence

This study investigated the prevalence of nasal carriage of staphylococci in dogs and determined the characteristics of the isolates. A total of 724 dogs from 87 veterinary practices across the mainland UK were screened for carriage of Staphylococcus spp. All isolates were examined for meticillin resistance (MR) and the presence of the mecA gene investigated in those isolates showing resistance. All coagulase-positive staphylococci and MR coagulase-negative staphylococci (MRCoNS) were subjected to antimicrobial susceptibility testing. Spa typing and DNA microarray analysis of resistance and virulence genes was carried out on all MR S. aureus (MRSA) and a subset of meticillin susceptible S. aureus (MSSA). Staphylococci were isolated from 399 (55.1%) of the dogs; only seven (1%) carried MRSA, all of which were identified as the dominant UK healthcare-associated strain (EMRSA-15, ST22). MSSA was identified in 47 (6.5%) dogs, the sequence types of which have been suggested as precursors to successful MRSA clones. Forty (5.5%) dogs carried MRCoNS, while no dogs carried MR S. pseudintermedius, although this is increasingly reported in mainland Europe. Resistance to antimicrobials among the isolates varied between species, with multidrug resistance (MDR) in 87.5% of MRCoNS and 21.8% of coagulase positive staphylococci. Microarray analysis of MRSA and a subset of MSSA isolates identified numerous virulence genes associated with pathogenesis, which are commonly identified in isolates of human origin. However, no isolates carried Panton-Valentine leukocidin (PVL) genes. This study suggests that MRSA carriage is low in the vet visiting dog population, but there is a diverse range of virulence and resistance determinants in canine S. aureus and MRCoNS isolates.

Antimicrobial susceptibility profiles of Staphylococcus intermedius isolates from clinical cases of canine pyoderma in South Africa

Successful treatment of canine pyoderma has become compromised owing to the development of antimicrobial resistance with accompanying recurrence of infection. Canine skin samples submitted to a veterinary diagnostic laboratory for microbiological culture and sensitivity between January 2007 and June 2010, from which Staphylococcus intermedius was isolated, were selected for this investigation. Antimicrobial resistance of S. intermedius was most prevalent with reference to ampicillin followed by resistance to tetracycline and then potentiated sulphonamides. In general, antimicrobial resistance was low and very few methicillin-resistant isolates were detected. Temporal trends were not noted, except for ampicillin, with isolates becoming more susceptible, and potentiated sulphonamides (co-trimoxazole), with isolates becoming more resistant. In general, both the Kirby-Bauer disc diffusion and broth dilution minimum inhibitory concentration tests yielded similar results for the antimicrobial agents tested. The main difference was evident in the over-estimation of resistance by the Kirby-Bauer test for ampicillin, co-trimoxazole, penicillin and doxycycline. Knowledge of trends in bacterial resistance is important for veterinarians when presented with canine pyoderma. Analysis of antimicrobial susceptibility profiles of S. intermedius isolated from canine pyodermas will guide veterinarians' use of the most appropriate agent and encourage prudent use of antimicrobials in companion animals.

Multilocus sequence typing for characterization of Staphylococcus pseudintermedius

Staphylococcus pseudintermedius is an opportunistic pathogen in dogs. Four housekeeping genes with allelic polymorphisms were identified and used to develop an expanded multilocus sequence typing (MLST) scheme. The new seven-locus technique shows S. pseudintermedius to have greater genetic diversity than previous methods and discriminates more isolates based upon host origin.

Nasal carriage of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma or both

In veterinary medicine, Staphylococcus schleiferi was previously assumed to be an inhabitant of carnivore skin, however, more recently, it has been repeatedly documented in the literature as both an inhabitant and as a pathogen. In order to determine the frequency of nasal carriage, and the methicillin susceptibility pattern of S. schleiferi from healthy dogs as well as dogs with otitis and/or pyoderma, a prospective study including 24 dogs with healthy ears and skin, 27 dogs with healthy ears and pyoderma, 15 dogs with otitis without pyoderma and 20 dogs with both otitis and pyoderma was performed. Specimens were obtained and cultured and isolates were identified as S. schleiferi based on growth and biochemical characteristics. S. schleiferi was isolated from the nares of 1 healthy dog, 3 dogs with recurrent pyoderma, 2 dogs with recurrent otitis, and 1 dog with both recurrent otitis and pyoderma. One of the S. schleiferi isolates was methicillin resistant. Nasal carriage of S. schleiferi does occur in healthy dogs as well as dogs with otitis and pyoderma. Methicillin resistant and sensitive S. schleiferi can be found in the nares of dogs with diseased ears and skin.

Resistência de bactérias isoladas de cães e gatos no Hospital Veterinário da Universidade Estadual de Londrina (2008-2009)

Foi determinado o perfil de resistência de bactérias isoladas de diversas afecções em cães e gatos atendidos no Setor de Clinica Cirúrgica de Animais de Companhia do Hospital Veterinário da Universidade Estadual de Londrina. Houve maior frequência de Staphylococcus spp. (27,6%), seguido por Pseudomonas spp. (22,7%) e Escherichia coli (16,6%). Na prova de sensibilidade antimicrobiana pelo método de difusão em ágar houve alta porcentagem de resistência das bactérias isoladas aos principais antibióticos usados no tratamento das infecções do trato urinário, principalmente das bactérias Gram negativas que apresentaram resistência superior a 66% aos antibióticos testados, com exceção da norfloxacina. Nas bactérias isoladas de feridas, apenas a gentamicina e a amicacina demonstraram índices de resistência inferior a 50,0%. Nas bactérias isoladas das afecções otológicas observou-se menor resistência à norfloxacina e maior à neomicina, sendo os menores índices de resistência observados nas bactérias Gram positivas. As bactérias Gram positivas apresentaram maior resistência à ciprofloxacina nos casos ortopédicos, e nas bactérias isoladas das peritonites houve 100% de resistência a diversos antibióticos. Este trabalho ressalta a importância da identificação bacteriana e a realização de antibiogramas para a escolha do agente antimicrobiano apropriado no tratamento das principais afecções atendidas na área de animais de companhia em medicina veterinária.

Efficacy of Argentine propolis formulation for topical treatment of canine otitis externa

The therapeutic effects of Argentine propolis ear drop formulation on canine otitis externa were evaluated. Forty-eight dogs with symptoms of otitis externa were randomly assigned to double-blinded, controlled clinical trial to evaluate the efficacy of topical formulation with propolis versus a topical placebo in the treatment of otitis externa. The propolis preparation and placebo were administrated into both external ear canals, twice daily for 14 days. Throughout the study, clinical examination and microbiological analysis of dogs ear exudates were made. The most frequent microorganisms isolated in culture media were: Malassezia pachydermatis (54.2%), Staphylococcus aureus (43.8%), coagulase-negative Staphylococcus (25.0%), Pseudomonas aeruginosa (20.8%), Candida albicans (18.8%), Proteus mirabilis (16.7%), Streptococcus spp. (16.7%), Enteroccocus faecalis (12.5%), Escherichia coli (12.5%), Staphylococcus intermedius (6.3%), Klebsiella spp. (4.2%), andCandida glabrata (2.1%). Whereas the control group did not recover from the infectious ear disease, the propolis preparation exhibited antimicrobial activity against most of the microorganisms isolated from samples of the treated group. In addition, no propolis-adverse effects were observed. This allowed propolis-treated patients to show a significant improvement of the clinical parameters. Thus, this new Argentine propolis ear drop formulation may be used for topical treatment of otitis externa in dogs.

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.

Antimicrobial susceptibility of Staphylococci isolated from naturally occurring canine external ocular diseases

OBJECTIVE

The purpose of this study was to describe the species distribution and antimicrobial susceptibility patterns of Staphylococci isolated from naturally occurring canine ocular diseases. SAMPLES AND PROCEDURES: Samples obtained from 68 dogs with signs of external eye disease were processed for isolation of bacteria of the genus Staphylococcus sp. Isolates were identified by biochemical reactions and tested for susceptibility to 11 antimicrobials of six classes.

RESULTS

Forty (58.8%) samples yielded Staphylococcus sp. in pure culture. Coagulase-positive Staphylococci were most common and Staphylococcus intermedius was the most frequent (45%) species, followed by S. aureus (22.5%) and the coagulase-negative species S. epidermidis (20%), and S. simulans (12.5%). Resistance to at least one drug was observed in 92.5% of the isolates, and multidrug resistance was a common finding (72.5%). The most effective drugs against Staphylococcus strains isolated from extra-ocular canine ocular diseases were ceftiofur and cefalexin.

CONCLUSION

This study highlights the presence of Staphylococcus sp. genus in naturally occurring extra-ocular canine ocular disease and the emergence of resistant strains to common antimicrobial drugs. It also emphasizes the need for bacterial culture with species identification and susceptibility testing in order to choose the appropriate antimicrobial therapy.

In vitro antimicrobial susceptibility of staphylococci isolated from canine pyoderma in Rio de Janeiro, Brazil

The study aimed to determine the etiology and antimicrobial resistance of staphylococci isolated from canine pyoderma. Samples were obtained from dogs with pyoderma and isolates were identified by biochemical reactions and tested for susceptibility to 15 antimicrobials. Thirty nine staphylococci isolates were obtained, and S. pseudintermedius was the most frequent (47.4%). All isolates showed resistance to at least one drug and 77.1% were multiresistant. The most effective drug was oxacillin. The study reports the alarming antimicrobial resistance of Staphylococcus isolated from canine pyoderma samples.

Species distribution and properties of staphylococci from canine dermatitis

The occurrence and phenotypic, and genotypic properties of 24 Staphylococcus isolates from canine dermatitis were investigated. The predominant staphylococcal species was Staphylococcus intermedius. The other species such as Staphylococcus chromogenes, Staphylococcus sciuri, Staphylococcus aureus, Staphylococcus saprophyticus, Staphylococcus epidermidis, and Staphylococcus capitis were only occasionally isolated. The study showed low level biochemical diversity among S. intermedius isolates. Resistance to antibiotics was frequently observed, with 87.5% of the isolates showing resistance to at least one drug. The most active antimicrobial agents against all staphylococci were amoxicillin/clavulanic acid, cephalexin and gentamicin. Resistance to carbenicillin, amoxicillin, ampicillin, cephadroxil, erythromycin, clinadmaycin and neomycin was common. No correlation was observed between antibiotic resistance and plasmid profile. PFGE analysis revealed a high degree of genetic polymorphism of S. intermedius, even among isolates collected in a restricted area over a short time.

Perfil de isolamento microbiano em cães com otite média e externa associadas

Comparou-se o perfil de isolamento microbiano de amostras coletadas de cães com otite média (OM) e externa (OE) associadas. Sessenta e quatro cães com otite média e externa foram avaliados durante 10 meses. Amostras dos condutos auditivos externos foram coletadas com auxílio de swabs estéreis e aquelas do ouvido médio pela técnica cirúrgica da osteotomia da bula timpânica. Os microrganismos foram cultivados e identificados de acordo com os métodos previamente descritos, e a susceptibilidade a antimicrobianos avaliada pelo método de difusão em ágar estabelecido pelo National Committee for Clinical Laboratory Standards. Bactérias anaeróbias estritas não foram isoladas em qualquer amostra. Todas as amostras de OE mostraram crescimento bacteriano e/ou fúngico. Na OM, a positividade nas culturas foi de 48%. Os microrganismos mais isolados na OE foram: Bacillus sp. (26,9%), M. pachydermatis (22,2%) e S. intermedius (21,7%); na OM foram: S. intermedius (32,5%), S. aureus subsp. aureus (22,5%) e bacilos Gram-negativos não fermentadores (10,0%). Observou-se alguma diferença no perfil de isolamento entre os quadros de OM e OE em 96,7% dos animais. Verificou-se elevada resistência de cepas de S. intermedius à penicilina G, ampicilina, eritromicina, tetraciclina e clindamicina.

Identification ofStaphylococcus piscifermentans from dog feces

The AD 2 strain isolated from feces of a healthy dog in Slovakia was characterized phenotypically by the conventional tests and commercial identification kits API Staph and ID32 Staph. Results of biochemical tests identified the strain as S. piscifermentans, fully corresponding with the species description. Further characterization by whole-cell protein profile analysis (SDS-PAGE) confirmed the identification based on biochemical tests and showed that the AD 2 strain is S. piscifermentans; lactic acid production, urease activity, bacteriocin production and the antibiotic susceptibility of it were also determined. S. piscifermentans AD 2 isolated first from an animal source was deposited in the Czech Collection of Microorganisms as Staphylococcus piscifermentans CCM 7165.

A comparative study of two antimicrobial/anti-inflammatory formulations in the treatment of canine otitis externa

The efficacy and tolerability of a marbofloxacin-clotrimazole-dexamethasone otic suspension (MCD) was compared with a standard topical treatment using a phase III clinical trial protocol. In a total of 140 dogs with clinical signs of acute or subacute otitis externa, Staphylococcus, Pseudomonas, Enterobacteriaceae and Malassezia were isolated from samples taken at inclusion to identify the causative pathogen; a further sample was collected in the event of failure or relapse, and from dogs (at day 14) for which Pseudomonas species had been isolated at inclusion. One group received MCD (10 drops per affected ear) once daily and a second received Surolan (containing polymyxin B, miconazole and prednisolone) (5 drops per affected ear), twice daily. Each group received treatment for 7 or 14 days according to the clinical outcome on day 7. Efficacy and tolerability were evaluated on days 7, 14 and, if necessary, 28 for dogs treated for 14 days. The trial demonstrated equivalence of both treatments in terms of efficacy, with a cure rate of 58.3% for MCD and 41.2% for Surolan. Both medications were equally well tolerated by dogs, but MCD was superior in terms of pain relief, decrease in pus quantity and smell, response rate and investigator's assessment on day 14.

Isolation of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both

OBJECTIVE

To determine the frequency of isolation and susceptibility patterns of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both that had or had not received antimicrobial treatment.

DESIGN

Prospective study.

ANIMALS

50 dogs.

PROCEDURE

Dogs were allocated to 1 of 4 groups: healthy dogs (n=13), dogs without otitis but with pyoderma (10), dogs with otitis but without pyoderma (11), and dogs with otitis and pyoderma (16). Bacteriologic culture of ear swab specimens was performed in all dogs. Bacteriologic culture of skin swab specimens was also performed in dogs with concurrent pyoderma. Isolates were identified as S schleiferi subsp schleiferi or S schleiferi subsp coagulans on the basis of growth and biochemical characteristics.

RESULTS

S schleiferi was not isolated from any dogs with pyoderma only. Staphylococcus schleiferi subsp schleiferi was isolated from the ears of 2 healthy dogs, and the skin and ears of 2 dogs and the skin of 1 dog with otitis and pyoderma. Staphylococcus schleiferi subsp coagulans was isolated from the ears of 3 dogs with otitis only, and the ears of 6 dogs and the skin of 2 dogs with otitis and pyoderma. One of the S schleiferi subsp schleiferi isolates from ears, 2 of the S schleiferi subsp coagulans isolates from ears, and 1 of the S schleiferi subsp coagulans isolates from the skin were resistant to methicillin. One methicillin-resistant isolate from the ears and 1 from the skin were also resistant to fluoroquinolones.

CONCLUSIONS AND CLINICAL RELEVANCE

S schleiferi subsp schleiferi was detected in healthy dogs and dogs with otitis and pyoderma. Methicillin-resistant and -susceptible S schleiferi subsp schleiferi and S schleiferi subsp coagulans were detected as the predominant organisms in dogs with otitis.

Evaluation of outcome of otitis media after lavage of the tympanic bulla and long-term antimicrobial drug treatment in dogs: 44 cases (1998-2002)

OBJECTIVE

To evaluate the outcome of otitis media in dogs after video-otoscopic lavage of the tympanic bulla and long-term antimicrobial drug treatment.

DESIGN

Retrospective study.

ANIMALS

44 dogs with otitis media treated in an academic referral practice.

PROCEDURE

Medical records were reviewed for signalment, duration of ear canal disease, previous medical treatments, dermatologic diagnosis, results of cytologic examination and microbial culture of ear canal exudate, findings during video-otoscopy, medical treatment, days to resolution, and maintenance treatments prescribed. Four independent variables (age, duration of ear canal disease prior to referral, use of corticosteroids in treatment regimens, and infection with Pseudomonas aeruginosa) were evaluated statistically for potential influence on time to resolution.

RESULTS

Mean +/- SD (range) duration of ear canal disease prior to referral was 24.9 +/- 21.6 (3 to 84) months. Otitis media in 36 dogs resolved after lavage of the tympanic bulla and medical management; mean +/- SD (range) time to resolution was 117 +/- 86.7 (30 to 360) days. Time to resolution was not significantly influenced by any variable evaluated. Three dogs were lost to follow-up, and 4 dogs eventually required surgical intervention. Seven of 36 dogs in which otitis had resolved relapsed; 4 required additional lavage procedures.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that lavage of the tympanic bulla combined with medical management is an effective and viable option for treatment of otitis media in dogs.

The use of otic powder in the treatment of acute external otitis

BACKGROUND

Acute external otitis (AEO) is a painful condition that results as a secondary infection of macerated skin and subcutaneous tissues of the external auditory canal. The most commonly causative microorganisms are Pseudomonas aeruginosa and Staphylococcus aureus. Classic management strategies include moisture prevention, cleansing of the canal and administration of topical antimicrobial agents in drop form, such as aminoglycosides and quinolones, at times in combination with steroid solutions. The objective of this study was to evaluate and compare the efficacy of topical otic powder, tobramycin drops and ciprofloxacin drops in patients suffering from AEO. MATERIALS AND MEASURES: A randomized prospective trial was performed to determine the efficacy of Auricularum powder (dexamethasone 10 mg, oxytetracycline HCl 90,000 U, polymyxin B Sulfate 100,000 U, nystatin 1,000,000 U; Trima, Serolam Laboratories, Germany) compared with ciprofloxacin (Ciloxan, Alcon Laboratories, Fort Worth, TX) and tobramycin (Tobrex, Alcon Laboratories) drops for the treatment of AEO. One hundred twenty patients who presented with signs and symptoms of AEO were enrolled. Inclusion criteria were: AEO diagnosed by an otolaryngologist, patient age 18 years, no prior treatment with other drops or systemic antibiotics, no sensitivity to any of the drugs used or their contents, and no perforation of the tympanic membrane. All patients were instructed to avoid moisture and wetness of the ear during the course of their treatment. After we received informed consent, a swab culture was taken, and the patient was randomly assigned topical treatment for 14 days.

RESULTS

Eighty-six percent of those treated with Auricularum powder were cured at day 3-4 after initial treatment. Seventy-seven percent of those treated with ciprofloxacin drops, and fifty-six percent of those treated with tobramycin were cured at that time. All 120 patients were cured by day 14.

CONCLUSION

The results show that topical treatment with Auricularum powder is an effective and rapid method for the treatment of AEO. Ciloxan also was effective in the treatment of AEO and relieved symptoms quickly and efficiently in a short period of time. Tobrex was effective in treating AEO, but our results show that relief of symptoms was slower than with the other drugs.

Antibiotic resistance in coagulase-negative staphylococci isolated from Cope's gray treefrogs (Hyla chrysoscelis)

Organisms belonging to the genus Staphylococcus were isolated on mannitol salt agar from the feces of wild caught Cope's gray treefrogs (Hyla chrysoscelis) from east-central Kansas. All 222 presumptive isolates were confirmed as coagulase-negative staphylococci with Staphylococcus sciuri and Staphylococcus xylosus being most prevalent. Antibiotic susceptibility patterns to five different antibiotics were determined and the results indicated 99% of all isolates were resistant to penicillin G and 59% of the isolates were resistant to oxacillin, a clinical substitute for methicillin. Due to the significance of methicillin resistance in the genus Staphylococcus, 10 randomly chosen oxacillin resistant organisms were analyzed for the presence of the mecA gene, which is known to code for methicillin resistance. The gene was detected in four of the 10 organisms examined. These data indicate that gray treefrogs are harboring inordinately large numbers of methicillin resistant staphylococci as part of their normal flora and that the mechanism of methicillin resistance may be independent of mecA.

Antimicrobial susceptibility of staphylococci isolated from the faeces of wild turkeys (Meleagris gallopavo)

AIMS

The purpose of this study was to investigate the staphylococcal flora associated with wild turkey populations.

METHODS AND RESULTS

Faecal samples obtained from 26 wild turkeys over a 16-month period were inoculated onto mannitol salt agar plates to select for staphylococci. Fifty-seven randomly chosen isolates were identified as Staphylococcus lentus and their susceptibility determined against clindamycin, chloramphenicol, ciprofloxacin, erythromycin, oxacillin, penicillin G, rifampin, tetracycline, trimethoprim-sulfamethoxazole, and vancomycin. Resistance was minimal as only 3 isolates showed resistance to clindamycin, 3 isolates were resistant to oxacillin, 3 isolates were resistant to penicillin G, and 1 isolate was resistant to erythromycin. Multiple antibiotic resistance was also minimal.

CONCLUSIONS

S. lentus is the predominant staphylococcal species associated with wild turkey faeces and antibiotic resistance in these organisms is not problematic.

SIGNIFICANCE AND IMPACT OF THE STUDY

S. lentus has been shown as a potential causative agent of inflammatory reactions in the respiratory tract. Due to increased numbers of wild turkeys and more frequent human exposure, surveys to monitor microbial populations are warranted.