Search Results (81)

Background/Objectives: Antimicrobial resistance (AMR) in companion animals is an emerging public health threat due to zoonotic potential and limited therapeutic options. Dogs with otitis externa may harbor multidrug-resistant (MDR) bacteria, including Escherichia coli (E. coli), Proteus mirabilis (P. mirabilis), and Enterobacter cloacae complex (E. cloacae complex), some producing extended-spectrum beta-lactamase (ESBL) or AmpC β-lactamases. This study aimed to assess the prevalence, AMR patterns, MDR occurrence, β-lactamase production, and co-infection profiles of these pathogens in canine otitis externa. Methods: Ear canal samples were collected from 592 dogs presenting clinical signs of otitis externa, with one sample per dog included in the analysis. Samples were collected from veterinary clinics in Timiș County, Romania, from 2022 to 2025. Samples were cultured on blood agar and MacConkey agar, followed by biochemical testing and MALDI-TOF mass spectrometry for bacterial identification. Antimicrobial susceptibility testing against 15 agents across six classes was performed using the VITEK^® 2 system. MDR and β-lactamase production (ESBL, AmpC) were determined according to CLSI 2018 veterinary guidelines. Co-isolation with bacterial and fungal species were recorded. Results: E. coli, P. mirabilis, and E. cloacae complex were isolated in 9.12%, 6.25%, and 1.2% of cases, respectively. E. coli exhibited the highest resistance to aminoglycosides (tobramycin 72.2%, gentamicin 61.1%) and full susceptibility to carbapenems. P. mirabilis showed the highest resistance to ampicillin (54%) and trimethoprim + sulfamethoxazole (46%), with complete susceptibility to carbapenems and fluoroquinolones. E. cloacae complex displayed universal resistance to cephalosporins but remained susceptible to non-cephalosporin β-lactams (piperacillin–tazobactam), carbapenems and aminoglycosides. MDR prevalence was 35.2% for E. coli, 18.9% for P. mirabilis, and 14.3% for the E. cloacae complex. ESBL production was detected in 13% of E. coli and 8.1% of P. mirabilis isolates, while all E. cloacae complex isolates were AmpC-positive. Co-isolations were common, primarily involving Staphylococcus pseudintermedius (S. pseudintermedius) and Malassezia pachydermatis (M. pachydermatis). Conclusions: MDR and β-lactamase-producing bacteria were identified in dogs with otitis externa, emphasizing the importance of routine antimicrobial susceptibility testing, targeted therapy based on local resistance profiles, and continuous AMR surveillance to prevent treatment failure and mitigate zoonotic risk. Full article

The canine ear microbiota plays an important role in ear health, and dysbiosis is associated with otitis externa (OE) and antimicrobial resistance (AMR). This study aims to investigate the ear microbiota of dogs with healthy ears and OE using bacterial culture-based methods and shotgun metagenomic sequencing, and to screen for AMR and virulence-associated genetic signatures. Ear swab specimens from 100 healthy and 100 OE-affected dogs were analyzed. The isolates obtained via bacterial culture were identified by MALDI-TOF MS and 16S rRNA sequencing. Metagenomic analysis was performed via Illumina shotgun sequencing. The most commonly defined species in healthy dogs in culture were Staphylococcus pseudintermedius (24.5%) and Staphylococcus epidermidis (5.7%); in dogs with OE, the most commonly defined species were S. pseudintermedius (30.5%), and Clostridium perfringens (4.5%). In healthy samples, metagenomic analysis revealed higher relative abundances of Bacteroides fragilis (15.8%) and Ezakiella coagulans (8.2%), while S. pseudintermedius (38.7%) dominated in OE. AMR profiling demonstrated diverse resistance determinants, including efflux pump systems and methicillin resistance-associated genes. In conclusion, the present study shows that S. pseudintermedius is a predominant member of canine ear microbiota, with higher presence in OE highlighting microbial shifts, and demonstrates that combining culture and metagenomic analyses provides a concise view of microbial communities and clinical relevance. Full article

Background/Objectives: Skull base osteomyelitis and necrotising otitis externa require prolonged antibiotic therapy, yet determining optimal treatment cessation timing remains challenging. Conventional imaging modalities demonstrate persistent abnormalities beyond infection resolution, confounding treatment decisions. This systematic review evaluated the diagnostic test accuracy of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) for treatment response monitoring in skull base osteomyelitis and necrotising otitis externa. Methods: We conducted a systematic review following PRISMA-DTA guidelines, searching MEDLINE, Embase, CENTRAL, CINAHL, Scopus, and Web of Science from inception to November 2025. Studies evaluating ¹⁸F-FDG PET diagnostic accuracy for treatment response assessment in confirmed skull base osteomyelitis or necrotising otitis externa were included. Two reviewers independently screened studies, extracted data, and assessed risk of bias using QUADAS-2. Bivariate random-effects meta-analysis was performed using MetaBayesDTA to obtain pooled sensitivity and specificity. Results: Eight studies comprising 154 lesions contributed to the primary analysis. Pooled sensitivity was 95.2% (95% credible interval 85.6–99.0%) and pooled specificity was 89.1% (95% credible interval 70.7–96.7%). The positive likelihood ratio was 8.7 (95% credible interval 3.2–28.4) and negative likelihood ratio was 0.05 (95% credible interval 0.01–0.17), with a diagnostic odds ratio of 172.0. Seven studies evaluating detection rate at initial presentation yielded a pooled rate of 96.1% (95% confidence interval 91.3–98.3%). SUVmax was the most frequently used metabolic parameter. Conclusions: ¹⁸F-FDG PET, specifically using SUVmax, demonstrates high sensitivity and good specificity for treatment response monitoring, with excellent capacity to rule out persistent infection. However, evidence quality is limited by retrospective designs and substantial heterogeneity. Prospective studies with standardised thresholds are needed to validate clinical utility. Full article

Although increasingly studied feline otitis externa (OE) prevalence is not yet well defined. The aim of this study was to assess the prevalence of OE in a population of privately owned cats in Northern Italy. Cats were clinically, otoscopically and cytologically evaluated. Diagnosis of OE was based on clinical findings along with abnormal ear cytology. The influence of the main demographic variables was examined. The prevalence of OE was 17% with a positive correlation to being European, and having short hair, a dermatological history, pruritus and multiple clinical signs. Ear cytology was abnormal in 19% of cats. Mites were found in 6% of the cats, about half of which were exclusively indoor cats and completely asymptomatic. Pathological numbers of bacteria and/or yeasts were found on cytology in 15% of cats and, of these, 29% had only Malassezia spp., 65% only cocci, and 6% a mixed population of these microorganisms. The prevalence of OE in owned cats in Northern Italy is relatively high. The identification of parasitic OE in asymptomatic and exclusively indoor cats, and a correlation between OE and dermatological history highlights the importance of systematic ear evaluation as part of routine feline health assessments. Full article

Congenital external auditory canal atresia (EACA) is a rare developmental anomaly in dogs with limited information to guide management. This report describes the clinical presentation, diagnostic work-up, surgical technique, and long-term outcome in two young dogs with unilateral congenital EACA. An 8-month-old Caucasian Shepherd and a 9-month-old Maltese presented with left-sided otalgia and absence of the external canal opening. Computed tomography identified segmental atresia of the vertical canal with intraluminal soft-tissue attenuating material and mild otitis externa and media in both dogs. Cytology and culture of canal contents were unremarkable, supporting a congenital, non-infectious origin. Both dogs underwent a canal-preserving vertical canal-to-external acoustic meatus anastomosis using a pull-through approach. Minor postoperative complications (partial wound dehiscence, mild canal stenosis) were successfully managed. At the 5-year and 1.5-year follow-up, respectively, both dogs remained free of clinical signs, with preserved hearing, supporting this procedure as a functional, cosmetically acceptable option in carefully selected dogs. Full article

Pseudomonas aeruginosa is a clinically important opportunistic pathogen in dogs and cats, frequently associated with chronic infections and increasing antimicrobial resistance. In 2024, 111 P. aeruginosa isolates from 77 dogs and 34 cats were analyzed. Isolates originated from the external ear canal of animals with chronic otitis externa (66/111, 59.5%) and the nasal cavity of animals with chronic rhinitis (29/111, 26.1%), wounds (7/111, 6.3%), the conjunctival sac (5/111, 4.5%), and the skin (4/111, 3.6%). MICs for ciprofloxacin, meropenem, ceftazidime, aztreonam, piperacillin, piperacillin/tazobactam, and colistin were determined using a commercial microdilution panel and interpreted with CLSI M100 breakpoints for P. aeruginosa. Susceptibility was highest to piperacillin and piperacillin/tazobactam (both 90.1% susceptible and 7.2% resistant). Resistance was more frequent to ciprofloxacin (26.1%), meropenem (17.1%), and ceftazidime (16.2%). Colistin resistance (MIC ≥ 4 µg/mL) was detected in 6.3% of isolates. MDR (Magiorakos definition; non-susceptibility to ≥1 agent in ≥3 antimicrobial categories) was identified in 17/111 (15.3%) isolates. Meropenem non-susceptibility was strongly associated with ceftazidime non-susceptibility (25/111, 22.5%; OR 11.21; 95% CI 4.29–29.30; phi 0.51; p = 2.4 × 10⁻⁷). These findings provide baseline phenotypic surveillance data for P. aeruginosa from companion animals in Poland and highlight clinically relevant co-non-susceptibility patterns involving meropenem and ceftazidime. Full article

Background/Objectives: Canine otitis externa (OE) is frequently complicated by Pseudomonas aeruginosa (P. aeruginosa) infections, which are often associated with treatment failure due to intrinsic and acquired antimicrobial resistance. This study aimed to assess the prevalence and antimicrobial susceptibility of P. aeruginosa isolates from dogs with OE in Timiș County, Romania, with a focus on aminoglycosides and fluoroquinolones, to provide region-specific, clinically relevant data and address potential public health implications. Methods: Exudate samples were collected from 435 dogs diagnosed with OE across multiple veterinary clinics between 2022 and 2025. P. aeruginosa isolates were identified using standard culture methods, and antimicrobial susceptibility was determined using the VITEK^® 2 Compact system according to CLSI VET01, Fifth Edition (2018) guidelines. Tested antibiotics included amikacin, gentamicin, enrofloxacin, marbofloxacin, and pradofloxacin. Resistance profiles were analyzed at both the individual antibiotic and class levels. Results:P. aeruginosa was isolated in 14.0% (61/435) of dogs. All isolates were susceptible to amikacin and gentamicin, whereas resistance to enrofloxacin and marbofloxacin was 27.9%, and pradofloxacin resistance reached 63.9%. A total of 24.6% of isolates were susceptible to all tested antibiotics. The most frequent multidrug-resistant combination among fluoroquinolones was ENR (R) + MAR (R) + PRA (R), observed in 23.0% of isolates. Conclusions: This study provides recent, region-specific data on P. aeruginosa prevalence and antimicrobial susceptibility in canine OE, offering clinically relevant insights into aminoglycoside and fluoroquinolone resistance. The findings highlight the potential public health significance of resistant P. aeruginosa strains at the human–animal interface and underscore the importance of antimicrobial stewardship in veterinary practice. Full article

Nystatin is a polyene macrolide antibiotic with broad-spectrum antifungal activity and serves as a key therapeutic agent for superficial fungal infections. This review systematically elaborates on its multicomponent chemical nature, its mechanism of action targeting ergosterol, and highlights the potential adverse effects, such as cardiotoxicity, associated with impurities like RT6 (albonoursin). The fundamental analytical techniques for quality control are outlined. Furthermore, the clinical applications and combination therapy strategies of nystatin in treating oral diseases, vaginitis, and otitis externa are summarized in detail. Regarding biosynthesis, the assembly mechanism of nystatin A₁ via the type I polyketide synthase pathway and its subsequent modification processes are thoroughly discussed. Emphasis is placed on the latest advances and potential of gene-editing technologies, particularly CRISPR/Cas9, in the targeted knockout of genes responsible for toxic components and in optimizing production strains to enhance nystatin yield and purity. Finally, this review prospects the future development of nystatin towards improved safety and efficacy through structural optimization, innovative delivery systems, and synthetic biology strategies, aiming to provide a reference for its further research and clinical application. Full article

Background: Canine skin and ear infections are common in small-animal practice and increasingly complicated by multidrug resistance (MDR), yet data from Serbia are limited. This study aimed to describe the bacterial etiology and antimicrobial resistance patterns in canine otitis externa and pyoderma. Methods: We retrospectively reviewed laboratory records from the Clinical Bacteriology and Mycology Laboratory, Faculty of Veterinary Medicine, University of Belgrade (January 2017–August 2024). A total of 422 non-invasive swabs from clinically ill dogs were included (ears: n = 210; skin: n = 212). Bacterial identification used conventional methods and commercial systems, and disk-diffusion susceptibility testing followed CLSI/EUCAST guidance. Methicillin resistance in staphylococci was assessed by cefoxitin/oxacillin screening; MRSA was confirmed by PCR and PBP2a detection. Resistance trends were compared between 2017–2020 and 2021–2024. Results: The leading pathogens were Staphylococcus pseudintermedius (ears 48.1%; skin 79.7%) and Pseudomonas aeruginosa (ears 29.1%; skin 7.6%). Staphylococci showed high resistance to macrolides, clindamycin, tetracycline, and first-line β-lactams (amoxicillin–clavulanate, cephalexin), with the highest susceptibilities to amikacin, florfenicol, and rifampicin. P. aeruginosa remained most susceptible to amikacin, polymyxin B, and imipenem. Between the two periods, S. pseudintermedius resistance increased to amikacin, fusidic acid, and cephalexin, while resistance to florfenicol decreased. P. aeruginosa resistance to imipenem increased. The prevalence of methicillin-resistant S. pseudintermedius (MRSP) was 27.4% (74/270). MDR S. pseudintermedius and MDR P. aeruginosa were identified in 38.5% and 53.3% of isolates, respectively. One isolate of each species was resistant to all tested drugs. Conclusions: These findings confirm high levels of antimicrobial resistance in major canine skin and ear pathogens and emphasize the need for susceptibility-based therapy, rational antimicrobial use, and ongoing surveillance in small-animal practice. Full article

Malassezia pachydermatis, an important opportunistic secondary pathogen, is often associated with atopic dermatitis or otitis externa in dogs. Recent studies indicate an increase in resistance of this yeast to commonly used antifungal agents. Therefore, the search for new antifungal agents is a challenge. In the present study, the susceptibility of M. pachydermatis strains to 10 plant essential oils—EOs (bergamot, grapefruit, coriander, hyssop, lavender, tea tree, nutmeg, oregano, rosemary, and Spanish sage) was determined using the broth microdilution method. All 15 clinical strains tested were susceptible to coriander (100%). A good antifungal activity was shown for EO from nutmeg (93.33%), bergamot (86.66), Spanish sage and hyssop (73.33%) and rosemary (66.67%). Lower antifungal efficacy was identified in EOs from grapefruit, lavender, tea tree and oregano (53.33%). The obtained results indicate promising prospects for the clinical use of essential oils in the treatment of M. pachydermatis infections. Full article

Background/Objectives: Antimicrobial resistance (AMR) in companion animals is a growing One Health concern due to the close interaction between pets and humans. Staphylococcus aureus (S. aureus) and Staphylococcus schleiferi (S. schleiferi) are common colonizers of the canine ear canal and can act as reservoirs of resistance. This study aimed to assess the prevalence and antimicrobial resistance profiles of S. aureus and S. schleiferi isolated from dogs with otitis externa and clinically healthy dogs in western Romania. Methods: A total of 973 canine ear swabs were collected, 503 from dogs with otitis externa and 470 from healthy dogs. Isolates were identified using MALDI-TOF MS. Antimicrobial susceptibility testing was performed using the VITEK^® 2 Compact system, bioMérieux, Marcy-l’Étoile, France, and interpreted according to CLSI VET01 guidelines, with 13 antimicrobials representing multiple drug classes. Results: S. aureus was more prevalent in healthy dogs (20%) than in otitis cases (4%), while S. schleiferi was more common in otitic samples (7.5% vs. 4%). Among S. aureus isolates from otitic dogs, penicillin resistance was highest (65%), and 25% were multidrug-resistant (MDR). In healthy dogs, S. aureus showed 54.3% penicillin resistance and 16% MDR prevalence. Four MRSA strains (4.3%) were identified only in healthy dogs. S. schleiferi exhibited the highest resistance to clindamycin, with MDR rates of 10.6% in otitic and 5.6% in healthy dogs. No MRSS strains were detected. Conclusions: Clinically healthy dogs may serve as asymptomatic carriers of resistant Staphylococcus strains, including MRSA. Routine antimicrobial susceptibility testing is essential to inform treatment choices and mitigate resistance dissemination within veterinary and public health contexts. Full article

Canine otitis externa is a common and recurrent ear infection in dogs, often caused by bacterial pathogens, and complicated by increasing antimicrobial resistance. The analysis of bacterial isolates from dogs with otitis externa revealed a predominance of Staphylococcus pseudintermedius, representing 41% of all cases, followed by Staphylococcus aureus (23%), and Pseudomonas aeruginosa (19%). Other less frequently isolated organisms included Escherichia coli, Streptococcus canis, and Proteus mirabilis. These results highlight the significant role of S. pseudintermedius in the pathogenesis of otitis externa in dogs, as well as the relevance of Gram-negative opportunistic pathogens like P. aeruginosa, which exhibits the highest recurrence rate, with 90% of the cases associated with highly resistant to β-lactams (93% for amoxicillin–clavulanic acid; >70% for third-generation cephalosporins). P. mirabilis showed complete resistance to tetracycline, partial resistance to doxycycline, and reduced susceptibility to carbapenems, nitrofurantoin, and polymyxin B. S. canis exhibited limited resistance to erythromycin and clindamycin, while S. epidermidis displayed extensive multidrug resistance, including β-lactams, fluoroquinolones, sulfonamides, and polymyxins. These findings highlight the high prevalence of multidrug-resistant pathogens in canine otitis externa, emphasizing the need for culture-guided therapy and raising concerns regarding One Health, due to potential zoonotic transmission and dissemination of genetic determinants of antimicrobial resistance. Full article

Rhodotorula spp. are ubiquitous red-pigmented yeasts increasingly reported as opportunistic animal pathogens. Recognition matters because underdiagnosis can misguide therapy, especially in companion-animal otitis externa. This review supports laboratory and clinical decisions by summarising taxonomy and ecology, host risk factors, diagnostics, virulence factors, antifungal susceptibility, and veterinary cases. This review addresses: (1) taxonomy and ecology; (2) clinical epidemiology and predisposing factors (immunomodulation, prior antibacterial therapy, chronic inflammation); (3) diagnostics—cytology, organism burden, repeat or pure culture, MALDI-TOF MS, ITS sequencing—with a brief comparison of feasibility in veterinary practice; (4) virulence factors—adhesion and biofilm on abiotic surfaces, hydrolytic enzymes, capsule in some strains, haemolysins, urease, and carotenoids that protect against oxidative stress; (5) antifungal susceptibility and therapy—intrinsic resistance to echinocandins, often high azole MICs, and the most consistent in vitro activity of amphotericin B ± flucytosine; and (6) a synthesis of veterinary case reports. Rhodotorula spp. should not be dismissed as contaminants when clinical signs match laboratory evidence; distinguishing infection from colonisation requires clinicomicrobiological correlation. This review highlights the need for standardised susceptibility testing and veterinary breakpoints, prospective data on burden and outcomes, better data on biofilm behaviour on clinical materials, environmental surveillance, and practical diagnostic and treatment guidance. Full article

Canine otitis externa (OE) presents a significant challenge in veterinary medicine due to its complex, multifactorial nature and the growing issue of antimicrobial resistance (AMR) associated with conventional antibiotic use. The objective of this study was to compare the efficacy of a novel, antibiotic-free topical ear solution (Therapy A) containing antimicrobial peptides and encapsulated plant extracts (chamomile, calendula, rosemary, and hops) against a standard conventional treatment (Therapy B) composed of gentamicin, betamethasone valerate, and clotrimazole. A longitudinal, randomized study was conducted over four weeks with 40 domestic dogs diagnosed with OE. The dogs were divided into two groups, each receiving one of the therapies. Evaluations were performed weekly, assessing clinical signs using the Otitis Index Scoring System (OTIS-3) and a pruritus visual analog scale (pVAS), as well as ear canal pH and cytology. The results showed that Therapy A provided similar clinical efficacy in OTIS-3 and pVAS scores that were comparable to Therapy B. Cytological analysis also revealed a significant reduction in microbial presence for both groups. Notably, Therapy A was clinically effective in two of the three dogs presenting multi-drug resistant (MDR) bacterial infections. The novel formulation also demonstrated a favorable safety profile, with no adverse drug reactions reported, in contrast to one dog in the conventional treatment group that experienced an adverse reaction. These findings suggest that the plant-based formulation is a safe and effective alternative for managing canine OE, offering a promising solution to reduce the reliance on antibiotics and corticosteroids. Full article

Background/Objectives: Staphylococcus pseudintermedius (S. pseudintermedius) is an opportunistic pathogen frequently isolated from dogs, involved in a wide range of infections, particularly otitis externa. Increasing antimicrobial resistance (AMR), including methicillin-resistant S. pseudintermedius (MRSP), poses significant challenges for veterinary and potentially human health. This study aimed to assess the prevalence and antimicrobial resistance profiles of S. pseudintermedius in dogs with otitis externa compared to clinically healthy dogs. Methods: Between 2022 and 2025, samples were collected from 400 dogs with otitis externa and 360 healthy dogs in veterinary clinics from Timișoara. Ear swabs were processed by conventional microbiological techniques and confirmed using MALDI-TOF MS. Antimicrobial susceptibility was tested using the VITEK^® 2 Compact system, following CLSI VET01, Fifth Edition (2018) standards. Fourteen antimicrobials from 11 classes were evaluated. Results: S. pseudintermedius was isolated in 40% of dogs with otitis externa and in 21.1% of healthy dogs. The highest resistance in both groups was observed to tetracycline (37.5% and 25%, respectively). No resistance was recorded to linezolid, vancomycin, teicoplanin, tigecycline, or fusidic acid. MRSP strains were identified in 1.2% of dogs with otitis, displaying multidrug resistance (MDR). MDR strains were also detected in 8.7% of diseased and 4% of healthy dogs, indicating the potential for subclinical reservoirs. Conclusions: The findings highlight the notable prevalence and AMR of S. pseudintermedius in both symptomatic and asymptomatic dogs. The detection of MRSP and MDR strains emphasizes the need for prudent antibiotic use and continuous AMR surveillance in veterinary medicine to mitigate zoonotic risks and preserve antimicrobial efficacy. Full article