Acinetobacter is one of the most relevant pathogenic and nosocomial bacteria in human medicine. However, in veterinary medicine, particularly in Spain, there are very few studies on the impact and frequency of infections due to this genus. The main objective of this study was to characterise Acinetobacter isolates recovered at the Complutense Veterinary Teaching Hospital of the Complutense University of Madrid (HCV-UCM), with special emphasis on detecting antimicrobial resistance. A total of 23 isolates obtained from different animal species and samples over a 25-year period were included in the study, based on their identification as Acinetobacter by VITEK-2. Identification was made by using MALDI-TOF, VITEK-2, whole-genome sequencing (WGS) and a chromogenic medium. WGS confirmed that 13 of the 23 isolates belonged to Acinetobacter spp. Antimicrobial susceptibility was interpreted according to CLSI guidelines using the Kirby-Bauer disk diffusion and broth microdilution method. The proportion of clinical isolates identified as Acinetobacter spp. at the HCV-UCM was 0.3%. Of these, 15.4% (2/13 isolates) were classified as multidrug-resistant. Two isolates with the highest MIC for tigecycline carried the tet(X) gene, and two isolates harboured mutations in both gyrA and parC QRDR regions. The results of this study suggest that, in this hospital, antimicrobial resistance among Acinetobacter isolates may not yet be widespread.

Aminoglycoside resistance mediated by 16S rRNA methyltransferases poses a growing threat in both human and veterinary medicine. Here, we conducted a retrospective genomic study of Enterobacterales isolates (n = 789) collected from clinical samples at a veterinary teaching hospital in Spain between 2011 and 2020. We identified four high-level aminoglycoside-resistant ST171 Enterobacter hormaechei subsp. xiangfangensis isolates carrying the armA gene, all from horses. Using Illumina and Nanopore sequencing, we determined that armA was located on a 70 kb IncR plasmid, also carrying other resistance genes such as msr(E), mph(E), blaDHA-1, and qnrB4, embedded within a Tn1548-like element. Genomic comparisons indicated that the IncR plasmid was linked to a 2008-2010 ST11 Klebsiella pneumoniae outbreak in companion animals at the same hospital, with >95% sequence plasmid identity. Although the IncR plasmid lacked conjugative genes, it was mobilizable in vitro via co-resident conjugative plasmids. To probe for an environmental reservoir, we sampled three horse stalls in 2022 and recovered 19 armA-positive isolates (E. hormaechei, Klebsiella pneumoniae, and Mixta calida) whose IncR plasmids were nearly identical to that found in clinical clones. Broader analysis of 1,330 IncR plasmids from the genomic plasmid database PLSDB revealed that most were mobilizable, frequently co-integrated with other replicons, and carried diverse resistance genes, though armA was uncommon. These findings demonstrate that non-conjugative IncR plasmids can persist in the environment and be horizontally disseminated to clinical isolates over a long period of time, underscoring the need for routine, plasmid-focused genomic surveillance in veterinary healthcare settings within a One Health framework.IMPORTANCEThe spread of antimicrobial resistance threatens both human and animal health. In veterinary hospitals, bacteria can share resistance genes not only through direct transmission but also via mobile plasmids that persist in the environment. In this study, we uncovered a decade-long persistence of a non-conjugative IncR plasmid carrying the armA gene, which confers high-level aminoglycoside resistance, in a Spanish veterinary teaching hospital. This plasmid was found in clinical isolates of Enterobacter hormaechei, Klebsiella pneumoniae, and Mixta calida from horses and from the hospital environment. Our findings show that even plasmids lacking self-transfer capability can be maintained and disseminated across bacterial species over many years. These results highlight the need for routine genomic surveillance of plasmids in veterinary healthcare settings to prevent long-term environmental reservoirs from fueling recurrent outbreaks.

Antimicrobial resistance (AMR) is a major global health threat, exacerbated by globalization which facilitates the spread of resistant bacteria. Addressing this issue requires a One Health perspective, involving humans, animals, and the environment. This study aims to compare the phenotypic resistance profiles of 69 clinical bacterial isolates (Enterobacteriaceae and Pseudomonaceae) from a Veterinary Teaching Hospital in Spain with their genotypic resistance profiles based on the presence of Extended-Spectrum Beta-Lactamases (ESBLs), AmpC and carbapenemases-enconding genes. For the genotypical analysis, whole genome sequencing (WGS) was used. Phenotypic characterization revealed that 37 isolates (53.6 %) grew on ESBL-selective medium. Phenotypic confirmatory tests showed that 12 strains (17.4 %) had some type of ESBL and 21 (30.4 %) could have an AmpC. Also, 24 isolates (34.8 %) grew in selective media for carbapenemases-producing bacteria, and 2 of these had a class A carbapenemase based on the KPC&MBL&OXA-48 disc kit. The genotypic analysis revealed 20 isolates (29 %) had blaTEM, 8 (11.6 %) had blaCTX-M and 7 (10.1 %) blaSHV. 27 (39.1 %) isolates had class C beta-lactamase genes. 35 isolates (50.7 %) had blaOXA, class D beta-lactamase. 37 strains (53.6 %) had an Inc. plasmid replicon associated with the spread of AMR genes, including beta-lactamases and carbapenemases. This study emphasizes the value of combining phenotypic and genomic analyses to better understand and address antibiotic resistance, especially in veterinary contexts. Integrating these approaches enhances diagnostic accuracy by identifying strains with resistance genes that may not show phenotypically, helping clinicians in anticipating resistance under selective pressure.

A canine population's immune resistance to canine distemper virus (CDV), canine parvovirus (CPV), and infectious hepatitis virus (CAV-1) was evaluated. In this study, a total of 112 sera were analyzed. Animals were considered as vaccinated if, in the last two years, they had received at least one dose of a vaccine that provides joint protection against CDV, CPV, and CAV-1. Animals that had never received any dose of these vaccines were designated as non-vaccinated. CDV, CPV, and CAV-1 antibodies were detected via a modified solid-phase enzyme-linked immunosorbent assay (ELISA), which detects IgG antibody levels in sera and provides semi-quantitative results in <30 min. In total, 41.1 % of the dogs had been vaccinated, and 58.9 % of dogs were designated as non-vaccinated. Overall, 90.2 %, 92.0 %, and 78.6 % of the tested dogs had positive results for the presence of IgG antibodies against CPV, CDV, and CAV-1, respectively. CPV antibodies were present in 87.9 % (58/66) of the vaccinated and 93.5 % (43/46) of the non-vaccinated dogs, while CDV antibodies were present in 95.5 % (63/66) of the vaccinated and 87.0 % (40/46) of the non-vaccinated dogs. Finally, CAV-1 antibodies were present in 84.8 % (56/66) of the vaccinated and of 69.6 % (32/46) the non-vaccinated dogs.

Despite previous reports on the emergence of Malassezia pachydermatis strains with decreased susceptibility to azoles, there is limited information on the actual prevalence and genetic diversity of azole-resistant isolates of this yeast species. We assessed the prevalence of azole resistance in M. pachydermatis isolates from cases of dog otitis or skin disease attended in a veterinary teaching hospital during a 2-year period and analyzed the ERG11 (encoding a lanosterol 14-alpha demethylase, the primary target of azoles) and whole genome sequence diversity of a group of isolates that displayed reduced azole susceptibility. Susceptibility testing of 89 M. pachydermatis isolates from 54 clinical episodes (1-6 isolates/episode) revealed low minimum inhibitory concentrations (MICs) to most azoles and other antifungals, but 11 isolates from six different episodes (i.e., 12.4% of isolates and 11.1% of episodes) had decreased susceptibility to multiple azoles (fluconazole, itraconazole, ketoconazole, posaconazole, ravuconazole, and/or voriconazole). ERG11 sequencing of these 11 azole-resistant isolates identified eight DNA sequence profiles, most of which contained amino acid substitutions also found in some azole-susceptible isolates. Analysis of whole genome sequencing (WGS) results revealed that the azole-resistant isolates from the same episode of otitis, or even different episodes affecting the same animal, were more genetically related to each other than to isolates from other dogs. In conclusion, our results confirmed the remarkable ERG11 sequence variability in M. pachydermatis isolates of animal origin observed in previous studies and demonstrated the value of WGS for disentangling the epidemiology of this yeast species. We analyzed the prevalence and diversity of azole-resistant Malassezia pachydermatis isolates in a veterinary hospital. A low prevalence of multi-azole resistance (c.10% of isolates and cases) was found. Whole genome and ERG11 sequencing of resistant isolates revealed remarkable genetic diversity.

BACKGROUND:Clostridioides difficile has been recognized as an emerging pathogen in both humans and animals. In this context, antimicrobial resistance plays a major role in driving the spread of this disease, often leading to therapeutic failure. Moreover, recent increases in community-acquired C. difficile infections have led to greater numbers of investigations into the animal origin of the disease. The aim of this study was to evaluate the genetic similarities between 23 environmental and animal isolates by using whole-genome sequencing and to determine antimicrobial resistance and virulence factor genes in toxigenic C. difficile strains to provide important data for the development of diagnostic methods or treatment guidelines. RESULTS:The most common sequence type was ST11 (87%), followed by ST2 (9%) and ST19 (4%). In addition, 86.95% of the strains exhibited multidrug resistance, with antimicrobial resistance to mainly aminoglycosides, fluoroquinolones, tetracycline and B-lactams; nevertheless, one strain also carried other resistance genes that conferred resistance to lincosamide, macrolides, streptogramin a, streptogramin b, pleuromutilin, oxazolidinone and amphenicol. In addition, a wide range of virulence factor genes, such as those encoding adherence factors, exoenzymes and toxins, were found. However, we observed variations between toxinotypes, ribotypes and sequence types. CONCLUSIONS:The results of this study demonstrated significant genetic similarity between ST11 strains isolated from environmental sampling and from animal origin; these strains may represent a reservoir for community-acquired C. difficile infection, which is becoming a growing public health threat due to the development of multridug resistant (MDR) bacteria and the number of virulence factors detected.

The role of small animal veterinary hospitals in the onset and dissemination of antimicrobial-resistant organisms (AMROs) is still not clear, and the implementation of an internal surveillance systems is a cost-effective tool to better understand their impact. The aim of this study was to describe a pilot program of active surveillance in a Spanish Veterinary Teaching Hospital, developed to estimate the detection frequency of AMROs in the commensal flora of patients and in the environment. Surveillance was focused on Methicillin-resistant Staphylococci (MRS), third generation cephalosporins resistant gram-negative bacteria (3GCR-GNB), and carbapenems-resistant gram-negative bacteria (CR-GNB). Oral and perirectal swabs were collected in dogs and cats hospitalized > 48hours, at admission and before discharge. Out of 50 patients sampled, 24% (n=12) were carriers at admission of at least one of the three investigated AMROs. Twenty-eight percent of patients acquired at least one AMRO during the hospital stay. MRS detection frequency at admission was 12%, while acquisition was 6%. 3GCR-GNB detection frequency was 14% at admission and acquisition 22%, while CR-GNB detection frequency was 2% at admission and acquisition 2%. Environmental surveillance (98 samples) showed a total detection frequency of 22.4% for MRS, 2% for 3GCR-GNB and CR-GNB. Clinical staff’ shoe soles showed high detection frequency for MRS (50%). 3GCR Escherichia coli was the most isolated species in patients (n=17). The results show how active surveillance can be used as a tool to assess the impact of AMROs in veterinary hospitals to subsequently build up tailored control plans based on specific issues.

Despite the increasing interest in studying the gut mycobiota of dogs, the association between fungal colonization and the development of digestive disorders in this species remains largely understudied. On the other hand, the high prevalence of antifungal-resistant yeasts detected in previous studies in samples from animals represents a major threat to public health. We analyzed the presence of culturable yeasts in 112 rectal swab samples obtained from dogs with digestive disorders attended in a veterinary teaching hospital. Our results revealed that Malassezia pachydermatis was frequently isolated from the studied dog population (33.9% of samples), and that the isolation of this yeast was significantly associated to the age of animals, but not to their sex, disease group, or the presence of vomits and/or diarrhea. In contrast, other yeast species were less prevalent (17.9% of samples in total), and their isolation was not significantly associated to any variable included in the analysis. Additionally, we observed that 97.5% of the studied M. pachydermatis isolates (n = 158, 1-6 per positive episode) displayed a minimum inhibitory concentration (MIC) value >4 mu g/ml to nystatin, 31.6% had a MIC >= 32 mu g/ml to fluconazole, and 27.2% had a MIC >4 mu g/ml to amphotericin B. The antifungal susceptibility profiles of non-Malassezia (n = 43, 1-7 per episode) were more variable and included elevated MIC values for some antifungal-species combinations. These results confirm that the intestine of dogs is a reservoir of opportunistic pathogenic yeasts and suggest that the prevalence of M. pachydermatis colonization depends more on the age of animals than on any specific digestive disorder.

Abstract Background Previous studies have demonstrated that fidaxomicin, a macrocyclic lactone antibiotic used to treat recurrent Clostridioides difficile-associated diarrhea, also displays potent in vitro bactericidal activity against Clostridium perfringens strains isolated from humans. However, to date, there is no data on the susceptibility to fidaxomicin of C. perfringens strains of animal origin. On the other hand, although combination therapy has become popular in human and veterinary medicine, limited data are available on the effects of antibiotic combinations on C. perfringens. We studied the in vitro response of 21 C. perfringens strains obtained from dogs and cats to fidaxomicin and combinations of fidaxomicin with six other antibiotics. Results When tested by an agar dilution method, fidaxomicin minimum inhibitory concentrations (MICs) ranged between 0.004 and 0.032 µg/ml. Moreover, the results of Etest-based combination assays revealed that the incorporation of fidaxomicin into the test medium at a concentration equivalent to half the MIC significantly increased the susceptibility of isolates to metronidazole and erythromycin in 71.4% and 61.9% of the strains, respectively, and the susceptibility to clindamycin, imipenem, levofloxacin, and vancomycin in 42.9–52.4% of the strains. In contrast, ¼ × MIC concentrations of fidaxomicin did not have any effect on levofloxacin and vancomycin MICs and only enhanced the effects of clindamycin, erythromycin, imipenem, and metronidazole in ≤ 23.8% of the tested strains. Conclusions The results of this study demonstrate that fidaxomicin is highly effective against C. perfringens strains of canine and feline origin. Although fidaxomicin is currently considered a critically important antimicrobial that has not yet been licensed for veterinary use, we consider that the results reported in this paper provide useful baseline data to track the possible emergence of fidaxomicin resistant strains of C. perfringens in the veterinary setting.

Antifungal-resistant fungi, including Aspergillus fumigatus and other Aspergillus species, pose an urgent threat to human and animal health. Furthermore, the environmental route of azole resistance selection due to the widespread use of azole fungicides in crop protection and other applications is a major public health issue. Although environmental surveillance of fungi is frequently performed in many zoological parks and wildlife rehabilitation centers, the antifungal susceptibility of recovered isolates is only rarely analyzed, which precludes a clear assessment of the threat posed by these fungi to captive animals. In this study, we assessed the presence of airborne azole-resistant Aspergillus spp., including the so-called ‘cryptic species’ (i.e., species which are phenotypically similar to more well-known aspergilli but clearly constitute different phylogenetic lineages) in a zoological park located in the city of Madrid, Spain. In general, our results revealed a low prevalence A. fumigatus and cryptic aspergilli with decreased susceptibility to azoles. However, we detected an A. fumigatus isolate with the TR34/L98H mutation in the gene encoding the lanosterol 14α-demethylase (Cyp51A), consisting of a tandem repeat of 34 base pairs in the promoter region and a lysine to histidine substitution at codon 98. Notably, this TR34/L98H mutation has been linked to the environmental route of azole resistance selection, thus highlighting the ‘One Health’ dimension of the emerging problem of antifungal resistance. In this context, continuous environmental surveillance of azole-resistant aspergilli in zoological parks and other similar animal facilities is recommended.

The emergence of resistance to antifungal drugs, and in particular to the azoles, is causing great concern in the scientific community. However, the actual impact of antifungal resistance on animal health and the farming system is mostly unknown, as animal mycoses have traditionally received much less attention than those affecting humans, and in vitro antifungal susceptibility testing of animal isolates is still uncommon. In this chapter, we briefly review the main characteristics of antifungal therapy in the veterinary setting and the current knowledge on antifungal resistance of some major animal pathogenic fungi, including yeasts such as Candida spp., Cryptococcus gattii, and Malassezia pachydermatis, and the filamentous fungus Aspergillus fumigatus. In addition, we discuss some issues that should be addressed in order to optimize antifungal therapies in animal medicine and minimize the impact caused by resistant strains, including the species-level identification of pathogenic fungi, the establishment of meaningful breakpoints for antifungal resistance of veterinary isolates, and the reduction of the environmental impact of antifungal use. We conclude that veterinarians and other animal health professionals should take action to demand more resources for improving the monitoring of antifungal resistances in veterinary clinics and animal facilities worldwide.

La edad dental es un indicador de maduración corporal de importancia clínica en Odontología para la planificación del tratamiento de pacientes en crecimiento. El objetivo de esta investigación fue establecer la precisión de la determinación de la edad dental calculada con el método Nolla, en un grupo de niños y niñas del Área Metropolitana de Caracas. Materiales y Métodos: Se seleccionó una muestra estratificada por edad y género incluyendo 238 radiografías panorámicas de elevada calidad de personas sanas con edades entre 5 y 13 años. Se calculó la diferencia entre la edad cronológica y dental distribuyéndola entre géneros y grupos de edad. Los datos fueron analizados utilizando pruebas de correlación (Pearson), y diferencias entre medias t -Student, ANOVA, fijando p<0,05. El coeficiente k intraobservador fue de 0,68. Resultados: La correlación entre la edad dental cronológica y la edad dental fue de 0,92 años (p=0,01). La formación dental se presentó retrasada en varones al compararla con la de las hembras, alcanzando significación estadística sólo para los caninos y primer premolar superior. Para el total, la diferencia entre la edad dental y cronológica fue estadísticamente significativa, registrándose una subestimación de la edad en -0,88 ± 0,94 años (p=0,01). La subestimación fue mayor para las hembras (-1,04±0,93 años) que para los varones (-0,72±0,94 años). Conclusión: Se concluye que el Método de Nolla puede ser utilizado para la identificación de etapas de formación dental en la población de niños y niñas venezolanos, aunque carece de precisión para el cálculo de su edad dental.

A total of 62 Prototheca bovis isolates from cases of bovine mastitis were tested for susceptibility to different antifungal compounds by the Clinical and Laboratory Standards Institute (CLSI) reference microdilution method and a commercial colorimetric microdilution panel (Sensititre YeastOne). All isolates displayed low susceptibility to echinocandins (MICs > 8 mu g/ml for anidulafungin, caspofungin, and micafungin), flucytosine (MIC > 64 mu g/ml), and the azoles enilconazole and fluconazole (MICs > 4 and > 64 mu g/ml, respectively). Moreover, 45.2, 32.3, and 1.6% of isolates had MICs> 4 mu g/ml for ketoconazole, terbinafine, and voriconazole, respectively, when tested by the CLSI method. In contrast, all isolates were more susceptible to the polyene compounds amphotericin B and nystatin, and itraconazole, posaconazole, and ravuconazole (MICs <= 2 mu g/ml, in all cases). Comparison of the results obtained in the CLSI and Sensititre methods showed excellent essential agreement (EA) for azoles (98.4% for itraconazole and posaconazole, and 100% for voriconazole) and moderate EA for amphotericin B (72.6%), when MICs were read after 48 and 24 h of incubation, respectively. In contrast, much lower EA values were obtained in some cases when the MICs for both techniques were determined after 48 h of incubation (e.g., 9.7% for amphotericin B and 69.4% for posaconazole). Therefore, the CLSI broth microdilution method and the Sensititre YeastOne panel can be used indistinctly for susceptibility testing of P. bovis isolates against azoles but not against amphotericin B until further optimization of the test conditions.

SummarySprouted cereals have a better digestibility and contain oligosaccharides that act as prebiotics improving and stabilising the intestinal flora. Supplementation with germinated malted barley could help to prevent the occurrence of colic in horses. The objective of this study was to determine if the inclusion of germinated barley as a supplement decreased the incidence of colic in a population of horses. An observational prospective study was designed to record the colic incidence of an equestrian centre horse population in Madrid (Spain). Data were collected during two 21 months periods, only including horses that were maintained at the centre for the whole time. Age, sex, housing and colic events were recorded during Period 1 (control period) and Period 2 (with germinated barley supplementation, Equinocol®). Sixty‐three horses were included in the study of which 43 were stabled 12 h/day (Group A) and 20 that lived at pasture all‐day long (Group B). Colic incidence of the total population, Group A and group B during Period 1 was 18.1, 23.9 and 5.7 cases/100 horses at risk‐year, respectively. With the inclusion of germinated barley, there was a significant decrease in the colic events in the total population (5.4 cases/100 horses at risk‐year) and group A (5.3 cases/100 horses at risk‐year). It was concluded that supplementation with germinated barley might decrease the appearance of colic in stabled horses. Further investigation is warranted to identify the potentially beneficial substances and the repeatability of the results.

The Staphylococcus pseudintermedius group (SIG) is an emerging threat in veterinary medicine, particularly methicillin-resistant (MRSP) isolates, which are frequently associated with multidrug resistance. Reliable identification of SIG members is critical to establish correct antimicrobial treatments. However, information on the molecular epidemiology and antimicrobial resistance patterns of MRSP in some regions is still limited. This study aimed to assess the antimicrobial resistance of SIG isolates recovered from animals at the Veterinary Teaching Hospital of Complutense University of Madrid (Spain) during a 10-year period (2007–2016). A total of 139 selected Staphylococcus isolates were subjected to species-level identification by different bioanalytical techniques (PCR, VITEK, MALDI-TOF) and subsequent antimicrobial susceptibility testing. Methicillin-resistant isolates (n = 20) were subjected to whole genome sequencing for further characterization of their antibiotic resistance determinants. Our results showed that there was a good correlation between PCR and MALDI-TOF identification, whereas VITEK showed very divergent results, thus confirming MALDI-TOF as a good alternative for species-level identification of coagulase-positive staphylococci. Notably, S. pseudintermedius, including the epidemic MRSP genotype ST71, was the only SIG species found among canine isolates. In addition, we found a high prevalence of multidrug resistance and resistance to fluoroquinolones, cephalosporins and macrolides. Finally, diverse genes associated with antibiotic resistance were detected among MRSP isolates, although the genetic basis of some of the resistant phenotypes (particularly to fluoroquinolones) could not be determined. In conclusion, our study reveals the circulation of MRSP in the veterinary setting in Spain, thus highlighting the emerging threat posed by this bacterial group and the need for further epidemiological surveillance.

Background: In Bogotá, 2,165 deaths from cardiovascular and respiratory diseases are attributed annually to air pollution. The impact on health due to air pollution in the Capital District, especially by PM10 is evident for the years 2015-2018. The proportion of children who presented wheezing in the last year was 74.3%, with a difference between greater and lesser exposure of 79.6% vs. 69.0% (p < 0.05). Symptoms of wheezing and expectoration were associated with higher PM10 exposure (RR 1.39 and 1.30). A child under 5 years of age exposed to PM10 is 1.70 times more at risk of being absent from school due to acute respiratory disease, and a decrease in PM10 would reduce this absence by 41.1%. The response from the health sector continues to be fragmented and reactive in the face of contingency levels of the environmental authorityObjective: Design in a participatory way a strategic plan of response of the health sector for the improvement of air quality.Results:1.Health Promotion-Air Governance: It is the participation of citizens in air management in Bogotá-Region.2.Collective Risk Management: Social communication of risk in both contingencies and pre-contingencies from the IBOCA: Bogota Air Quality Index.3. Individual Risk Management: It is the counseling or orientation that is done in the outpatient consultation to the general population and in patients with basic diseases on air quality and health. It also includes the assessment of population vulnerability to air pollution from the life course and the socioeconomic condition of individuals, families and communities.4.Public Health Management: Inclusion of estimates of exposure to air pollution through averages closest to the population: nowcast.Conclusions: Through a knowledge translation methodology and with institutional and citizen participation, the preparation of a proposal for a Strategic Plan for the Health Sector against Air Pollution was achieved.

The present study focused on detecting the presence of Clostridium difficile on veterinary hospital surfaces of large and small animal areas at the Universidad Complutense of Madrid. Isolated C. difficile strains were further characterized and investigated for antimicrobial susceptibility testing. Of n = 23 sampling area, 17% were positive for the presence of C. difficile. The isolates belonged to PCR ribotypes 078, 014, 039, and 154, of which RT 078 and 014 are also frequently found as human pathogens. Two isolates had high level resistance to metronidazole. These results suggest that the veterinary hospital environment constitutes a potential reservoir of zoonotical transferable C. difficile. (C) 2019 Elsevier Ltd. All rights reserved.

Combination therapy has become popular in clinical practice, but limited data on the effects of combinations of antifungal agents is still available for most fungal pathogens. We studied the in vitro response of 30 genetically diverse clinical strains of the basidiomycetous lipophilic yeast Malassezia pachydermatis obtained from cases of canine otitis to several amphotericin B (AMB)-azole combinations. Broth microdilution checkerboard tests revealed that AMB antagonized the effects of itraconazole (ITC) and voriconazole (VRC) in 50% and 6.7% of the strains, respectively, but did not interact with fluconazole or posaconazole (fractional inhibitory concentration index (FICI) values were <4 in all cases). Subsequent Etest-based assays performed for a subset of strains did not confirm the antagonism between AMB and ITC or AMB and VRC. In summary, the results of this study suggest that antagonistic combination effects between AMB and azoles might occur when tested against M. pachydermatis. Nevertheless, as observed for other fungi, different in vitro analyses yielded contrasting results, and the response to AMB-azole combinations was compound- and strain-dependant.