BACKGROUND: Cytological detection of acantholytic keratinocytes (acantholytic cells [AC]) helps to identify canine pemphigus foliaceus (cPF) yet AC also occurs in superficial pyoderma (SP), the main differential diagnosis.
OBJECTIVE: To compare selected cytomorphological features of cPF and SP and to establish cytological diagnostic criteria that could differentiate cPF from SP.
METHODS: 40 and 51 client-owned dogs with PF and SP, respectively.
METHODS: Impression smears from cPF (64), impetigo (40) and exfoliative superficial pyoderma (ESP) (17) samples were stained with Romanowsky stain, randomised, blinded and evaluated by two investigators independently. The entire sample was screened (×500 or ×1000 magnification) for round (AC1), boat (AC2) and raft AC, eosinophils and bacteria. Interobserver agreements were calculated.
RESULTS: The average number of the 10 highest ×500 fields for AC1 and AC2 was significantly higher in PF than SP (p < 0.0001; Kruskal-Wallis test). Rafts and eosinophils were more common in PF than SP (p < 0.0001; chi-square test), while bacteria were rare in PF (5%; p < 0.0001; chi-square test). Observations between the experienced and novice investigators were highly correlated. An ROC analysis identified five AC1/×500-magnification field as a suitable cut-off value for predicting PF diagnosis. This cut-off value was tested by two additional investigators, who identified sensitivity of 84%-100%, specificity of 95%-97% and accuracy of 95%-96% for the diagnosis of cPF.
CONCLUSIONS: Criterion-based impression smear cytological evaluation can provide strong evidence to support the clinical diagnosis. Acantholytic cell morphology varies in cPF and SP, and experience can improve accuracy in cytological differentiation.

Staphylococcus pseudintermedius is one species in the commensal staphylococcal population in dogs. While it is commonly carried on healthy companion dogs it is also an opportunistic pathogen associated with a range of skin, ear, wound and other infections. While adapted to dogs, it is not restricted to them, and we have reviewed its host range, including increasing reports of human colonisation and infections. Despite its association with pet dogs, S. pseudintermedius is found widely in animals, covering companion, livestock and free-living species of birds and mammals. Human infections, typically in immunocompromised individuals, are increasingly being recognised, in part due to improved diagnosis. Colonisation, infection, and antimicrobial resistance, including frequent multidrug resistance, among S. pseudintermedius isolates represent important One Health challenges.

BACKGROUND: Streptococcus pyogenes causes more than 500 000 deaths per year globally, which occur disproportionately in low-income and middle-income countries. The roles of S pyogenes skin and pharyngeal carriage in transmission are unclear. We aimed to investigate the clinical epidemiology and household transmission dynamics of both S pyogenes asymptomatic carriage and infection in a high-burden setting.
METHODS: We did a 1-year prospective, longitudinal, household cohort study, recruiting healthy participants from households in Sukuta, The Gambia. Households were eligible if they comprised at least three members, including one child younger than 18 years, and were excluded if more than half of household members declined to participate. Households were identified by random GPS coordinates derived from census data. At monthly visits, pharyngeal and normal skin swabs were collected for S pyogenes culture, and sociodemographic data were recorded by interview. Incident pharyngitis and pyoderma infections were captured. Cultured isolates underwent emm genotyping. The primary outcome measures were incidence of S pyogenes carriage and disease. Additional outcomes were prevalence of S pyogenes skin and pharyngeal carriage, S pyogenes skin and pharyngeal clearance time, S pyogenes emm type, risk factors for carriage and disease events, household secondary attack rate, and emm-linked household transmission events. The study is registered on ClinicalTrials.gov, NCT05117528.
RESULTS: Between July 27, 2021, and Sept 28, 2022, 442 participants were enrolled from 44 households. The median age was 15 years (IQR 6-28) and 233 (53%) were female. We identified 17 pharyngitis and 99 pyoderma events and 49 pharyngeal and 39 skin S pyogenes carriage acquisition events. Mean monthly prevalence was 1·4% (95% CI 1·1-1·9) for S pyogenes pharyngeal carriage and 1·2% (0·9-1·6) for S pyogenes skin carriage. Incidence was 120 per 1000 person-years (95% CI 87-166) for S pyogenes pharyngeal carriage, 124 per 1000 person-years (90-170) for S pyogenes skin carriage, 51 per 1000 person-years (31-84) for S pyogenes pharyngitis, and 263 per 1000 person-years (212-327) for S pyogenes pyoderma. Pharyngeal carriage risk was higher during the rainy season (HR 5·67, 95% CI 2·19-14·69) and in larger households (per additional person: 1·03, 1·00-1·05), as was pharyngitis risk (rainy season: 3·00, 1·10-8·22; household size: 1·04, 1·02-1·07). Skin carriage risk was not affected by season or household size, but was lower in female than in male participants (0·45, 0·22-0·92) and highest in children younger than 5 years compared with adults (22·69, 3·08-167·21), with similar findings for pyoderma (female sex: 0·34, 0·19-0·61; age <5 years: 7·00, 2·78-17·64). Median clearance time after carriage acquisition was 4·0 days for both skin (IQR 3·5-7·0) and pharynx (3·5-7·3). The mean household secondary attack rate was 4·9 (95% CI 3·5-6·3) for epidemiologically linked S pyogenes events and 0·74 (0·3-1·2) for emm-linked S pyogenes events. Of the 204 carriage and disease events, emm types were available for 179 (88%). Only 18 emm-linked between-visit household transmission events were identified. Pyoderma was the most common source of S pyogenes household transmissions in 11 (61%) of 18 emm-linked transmissions. Both pharynx to skin and skin to pharynx transmission events were observed.
CONCLUSIONS: S pyogenes carriage and infection are common in The Gambia, particularly in children. Most events are non-household acquisitions, but skin carriage and pyoderma have an important role in S pyogenes household transmission and bidirectional transmission between skin and pharynx occurs.
BACKGROUND: Wellcome Trust, Chadwick Trust, Fonds National de la Recherche Scientifique (Belgium), European Society for Paediatric Infectious Diseases, and Medical Research Council (UK).

Staphylococcus pseudintermedius is the most common cause of pyoderma in dogs. We validated a point-of-care (PoC) test based on colorimetric loop-mediated isothermal amplification (LAMP) for rapid S. pseudintermedius identification and susceptibility testing for first line antimicrobials for systemic treatment of canine pyoderma, i.e., lincosamides, first generation cephalosporins and amoxicillin clavulanate. Newly designed LAMP primers targeting clinically relevant resistance genes were combined with a previously validated set of primers targeting spsL for species identification. After laboratory validation on 110 clinical isolates, we assessed the performance of the test on 101 clinical specimens using routine culture and susceptibility testing as a reference standard. The average hands-on and turnaround times for the PoC test were 30 and 90 min, respectively. The assay showed sensitivity and specificity near 100% for both species identification and susceptibility testing when performed on bacterial cultures or clinical specimens in the laboratory. However, the PoC test yielded less accurate results when performed on-site by clinical staff (92% sensitivity and 64% specificity for species identification, 67% sensitivity and 96% specificity for β-lactam susceptibility, and 83% sensitivity and 71% specificity for lincosamide susceptibility). These results indicate that the PoC test should be adapted to a user-friendly technology to facilitate performance and interpretation of results by clinical staff. If properly developed, the test would allow veterinarians to gain rapid information on antimicrobial choice, limiting the risk of treatment failure and facilitating adherence to antimicrobial use guidelines in small animal veterinary dermatology.

Background: Pyoderma vegetans (PV) is a rare neutrophilic dermatosis of unknown etiology. Currently, there are no treatment guidelines for PV. Systemic steroids are often used as first-line therapy, but recurrence upon discontinuation or tapering is common.Materials and methods: We tested the efficacy of doxycycline at a dose of 200 mg/d to treat resistant PV.Results: After 4 weeks of treatment we noticed a significant improvement in the clinical appearance of PV.Conclusions: Our case demonstrates the potential utility of doxycycline as a systemic steroid-sparing agent in the treatment of PV.

Cutaneous manifestations of hematologic malignancy represent both a clinical challenge for the treating physician and a pathophysiological model for advancing the knowledge on individual neoplasms. Indeed, a growing body of evidence supports the concept of recurrent molecular defects associating with specific clinical features, as best exemplified by VEXAS. Herein neutrophilic and eosinophilic dermatoses of potential interest for both hematologists and dermatologists will be reviewed, including subcorneal pustular dermatosis-type IgA pemphigus, neutrophilic eccrine hidradenitis, Sweet\'s syndrome as well as myelodysplasia cutis and VEXAS, pyoderma gangrenosum, eosinophilic annular erythema, eosinophilic dermatosis of hematological malignancy, Wells syndrome and cutaneous involvement in hypereosinophilic syndromes. Possible management approaches are discussed for each, emphasizing scenarios that require treatment of the underlying condition to achieve remission at the skin level.

Staphylococcus coagulans (SC) belongs to a group of coagulase-positive staphylococci occasionally isolated from the skin lesions of dogs with pyoderma. We recently revealed that erythritol, a sugar alcohol, inhibited the growth of SC strain JCM7470. This study investigated the molecular mechanisms involved in this growth inhibition of JCM7470 by erythritol, and determine whether erythritol inhibits the growth of SC isolated from the skin of dogs with pyoderma. Comprehensive analysis of the gene expression of JCM7470 in the presence of erythritol revealed that erythritol upregulated the expression of glcB and ptsG genes, both of which encode phosphotransferase system (PTS) glucoside- and glucose-specific permease C, B, and A domains (EIICBA), respectively, associated with sugar uptake. Moreover, erythritol suppressed in vitro growth of all 27 SC strains isolated from the skin lesions of canine pyoderma, including 13 mecA gene-positive and 14 mecA gene-negative strains. Finally, the growth inhibition of the SC clinical isolates by erythritol was restored by the addition of glucose. In summary, we revealed that erythritol promotes PTS gene expression and suppresses the in vitro growth of SC clinical isolates from dogs with pyoderma. Restoration of the erythritol-induced growth inhibition by glucose suggested that glucose starvation may contribute to the growth inhibition of SC.

Bacterial culture and susceptibility are widely used in veterinary medicine to determine the specific bacteria causing infection as well as aid in appropriate antimicrobial selection. Previous studies have shown variable results with culture and susceptibility depending on the laboratory and methodology used. Samples from dogs with superficial pyoderma were obtained to make a homogeneous solution of bacteria. Sample acquisition from this solution was randomized and submitted to four veterinary laboratories for microbial identification and sensitivity. There was fair agreement among the laboratories in identification of a Staphylococcus spp. as well as fair agreement among the laboratories on the same Staphylococcus sp. Very good agreement was noted on identification of methicillin-resistant Staphylococcus spp. Additionally, good to very good agreement was noted on all antimicrobials that were tested across all four laboratories. A difference in turnaround time for sample processing was observed between the laboratories in the present study. Overall, there was mild variability among the laboratory results in this study.

Erythritol (ERT) and L-ascorbyl-2-phosphate (APS) are bacteriostatic, but their effects on staphylococcal skin infections remain unknown. We aimed to determine whether ERT combined with APS inhibits the growth of staphylococci that are commonly isolated from pyoderma skin lesions in dogs. We investigated the individual and combined effects of ERT and APS on the growth of Staphylococcus pseudintermedius, S. schleiferi, and S. aureus using turbidity assays in vitro. Skin lesions from 10 dogs with superficial pyoderma were topically treated with 5% ERT and 0.1% APS for 28 days, and swabbed skin samples were then analyzed using 16S rRNA amplicon sequencing and quantitative real-time PCR (qPCR). Results showed that ERT inhibited S. pseudintermedius growth regardless of harboring the mecA gene, and APS increased the inhibitory effects of ERT against S. pseudintermedius, S. schleiferi, and S. aureus in vitro. Moreover, combined ERT and APS decreased the prevalence of staphylococci on canine skin lesions at the genus level. The combination slightly increased the α-diversity but did not affect the β-diversity of the microbiota. The qPCR results revealed that the combination significantly decreased S. pseudintermedius and S. schleiferi in skin lesions. Topical administration of EPS combined with APS can prevent staphylococcal colonization on the surface of mammalian skin. The results of this study may provide an alternative to systemic antibiotics for treating superficial pyoderma on mammalian skin surfaces.

Dogs often carry methicillin-resistant Staphylococci asymptomatically. These bacteria are frequently linked to conditions such as canine pyoderma and otitis. Close interaction between dogs and humans can facilitate the exchange of resistant strains, particularly Methicillin-resistant Staphylococcus pseudintermedius (MRSP). This represents a public health issue, since these strains, in addition to occasionally causing infections in humans, can also serve as a source of resistance and virulence genes for strains of greater importance in human medicine, such as Staphylococcus aureus. Furthermore, MRSP strains are often multidrug resistant, which ends up compromising the treatment of infections. This study aimed to assess the potential transmission of Staphylococcus pseudintermedius among dogs and their owners. We examined a total of one hundred canine samples collected from cases of pyoderma and otitis to detect the presence of staphylococci. Simultaneously, we conducted evaluations on all dog owners. Staphylococci strains were identified using MALDI-TOF MS and PCR targeting the nuc gene. Methicillin resistance screening was also performed by detecting the mecA gene using PCR. Among the sampled dogs, 64 carried S. pseudintermedius. Nine were identified as MRSP. In six instances, dogs and their owners exhibited S. pseudintermedius. These samples underwent genome sequencing and were screened for antimicrobial resistance genes, SCCmec typing, MLST characterization, and Single Nucleotide Polymorphisms (SNP) analyses. The results of the phylogenetic analysis revealed that in three cases, dogs and owners had closely related isolates, suggesting interspecies transmission. Two of these cases involved MRSP and one MSSP. Moreover, in the two MRSP cases, the same SCCmec type (type V) was detected. Additionally, the sequence type was consistent across all three cases involving dogs and owners (MSSP ST2277, MRSP ST2282, and ST2286). These findings strongly indicate a transmission event. Since Staphylococcus pseudintermedius is primarily isolated from canine samples, it is plausible that dogs may have acted as a potential source. In the remaining three cases, despite identifying the same species in both samples, they had notable phylogenetic differences.