Prevalence of Bacterial Species in Skin, Urine, Diarrheal Stool, and Respiratory Samples in Cats

Staphylococcus felis C4 exhibits in vitro antimicrobial activity against methicillin-resistant Staphylococcus pseudintermedius in a novel canine skin explant model

BACKGROUND

Canine superficial pyoderma is a common bacterial skin infection of dogs, generally caused by Staphylococcus pseudintermedius. The C4 strain of Staphylococcus felis was recently discovered to have strong antimicrobial activity against S. pseudintermedius in mice.

OBJECTIVES

We aimed to evaluate in vitro if this antimicrobial activity was maintained using a novel canine skin explant model.

MATERIALS AND METHODS

Punch biopsies (8 mm) of skin from recently euthanised dogs were collected and placed into six-well plates on top of an agarose pedestal.

RESULTS

Histological examination of the skin explants showed an intact dermal-epidermal organisation and a stratum corneum that was successfully colonised by S. pseudintermedius after topical application. The number of colony forming units of S. pseudintermedius showed a 2 log increase after 24 h colonisation, indicating that the explant supported bacterial growth. By contrast, co-treatment with S. felis C4 live bacteria and its sterile protein product significantly reduced the growth of a methicillin-susceptible (ST540, p = 0.0357) and a methicillin-resistant (MR) strain (ST71, p = 0.0143) of S. pseudintermedius. No detectable bacteria were recovered from or visualised on skin 24 h posttreatment with the S. felis C4 sterile protein product.

CONCLUSIONS AND CLINICAL RELEVANCE

Using a novel canine explant model, we demonstrate that the S. felis C4 strain inhibits the growth of S. pseudintermedius and that it is a promising candidate for a new probiotic therapy to treat cutaneous infections caused by S. pseudintermedius, including MR strains.

Baicalin Exhibits a Protective Effect against Cisplatin-Induced Cytotoxic Damage in Canine Renal Tubular Epithelial Cells

Renal failure is a common chronic disease in dogs that substantially affects both their quality of life and longevity. The objective of this study was to assess the protective mechanisms of baicalin in cisplatin-induced Madin-Darby canine kidney (MDCK) epithelial cells' apoptosis model and explore the impacts of baicalin at varying doses on various indexes, such as cisplatin-induced MDCK cell apoptosis, oxidation and antioxidation, and inflammatory factors. (Methods) MDCK cells in the logarithmic growth phase were randomly divided into a control group, a model group (20 μmol/L cisplatin), and a baicalin-protection group (20 μmol/L cisplatin + 50, 25 μmol/L baicalin) and received the corresponding treatments for 24 h. The effects of cisplatin on MDCK cell apoptosis, oxidation and antioxidation, inflammatory factors, and other indicators were studied, and the relieving effect of baicalin on cisplatin-induced MDCK cell damage was explored. Calcein/PI staining and Annexin V-FITC/PI staining showed that cisplatin induced the apoptosis of MDCK cells, while baicalin effectively reduced the damage caused by cisplatin. The ELISA results demonstrated a significant elevation in the nitric oxide (NO) and malondialdehyde (MDA) levels within the MDCK cells following treatment with cisplatin (p < 0.01). In addition, superoxide dismutase (SOD), glutathione peroxidase (GSH), and catalase (CAT) activities remarkably declined (p < 0.01), while tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) expression within the MDCK cells were apparently elevated (p < 0.01). However, baicalin treatment resulted in opposite changes in these factors. The findings suggested that baicalin exhibits potential in mitigating cisplatin-induced oxidative stress and inflammation in MDCK cells. As revealed with the Western blot results, cisplatin promoted P62, P53, and BAX protein levels, increased mTOR phosphorylation, inhibited AMPK phosphorylation, and reduced Beclin1 and BCL-2 protein levels. However, a contrasting trend was observed following baicalin treatment. Cisplatin can inhibit the activity of MDCK cells, lead to abnormalities in oxidation and antioxidation functions and cell inflammatory factors, and accelerate cell apoptosis. Moreover, baicalin can significantly alleviate the damage of cisplatin to MDCK cells.

The detection and phylogenetic characterization of Cryptosporidium, Cystoisospora, and Giardia duodenalis of cats in South Korea

Introduction

Cryptosporidium, Cystoisospora, and Giardia duodenalis are gastrointestinal protozoa parasites that cause diarrhea in various animals. However, information regarding the detection and phylogenetic characterization of gastrointestinal protozoa parasites in cats is limited throughout South Korea. Therefore, this study aimed to determine the detection and identify subspecies of gastrointestinal protozoa parasites in cats from South Korea.

Methods

A total of 290 fecal samples were collected from stray, companion, and shelter cats in six provinces. Cryptosporidium, Cystoisospora, and G. duodenalis were identified by PCR. All positive samples were subtyped by PCR and sequencing of gp60, ITS-1, tpi, bg, and gdh.

Results

The overall detection of gastrointestinal protozoan parasitic infection was 17.93%. G. duodenalis was the most prevalent, with 7.93%, followed by Cystoisospora spp. (7.24%) and Cryptosporidium spp. (4.48%). In addition, C. felis (n=10), C. parvum (n=2), C. ryanae (n=1), Cystoisospora felis (n=14), Cystoisospora suis (n=5), Cystoisospora ohioensis (n=1), Cystoisospora spp. were identified in subspecies analysis of positive samples. C. felis showed a significant association with diarrhea (7.81%) and living condition (6.04%), and Cystoisospora felis in diarreha (9.38%) according to detection. Through phylogenetic analysis of the tpi, bg, and gdh genes from 23 G. duodenalispositive samples, it was confirmed that the samples of present study belonged to assemblage A, B, C, and D.

Discussion

South Korean cats have a high rate of gastrointestinal protozoan parasites infection with cat-specific Cryptosporidium and Cystoisospora, which are associated with living conditions and diarrhea symptoms. Moreover, zoonotic and other animal-specific subtype of protozoan parasites have been detected in cat feces.

Gut microbiota differences induced by Toxoplasma gondii seropositivity in stray cats in South Korea

T. gondii is a highly prevalent parasite worldwide, with cats serving as its final host. However, few studies have investigated the impact of T. gondii infection on cat gut microbiota. Therefore, this study examined the influence of T. gondii infection on the gut microbiota of stray cats and identified potential pathogens in their feces. This study examined T. gondii infection through blood of stray cats and the influence of microbiota in their feces using 16S rRNA gene amplicon sequencing. The results revealed significant differences in gut microbiota composition and diversity between the T. gondii seropositive and seronegative groups. Seropositive samples displayed a lower number of operational taxonomic units and reduced Shannon index than the seronegative samples. The seropositive and seronegative groups exhibited enrichment of taxa, including Escherichia and Enterobacteriaceae and Collinsella, Bifidobacterium, and Roseburia, respectively. Furthermore, potential pathogen species, including Campylobacter, Escherichia, and Streptococcus, were identified in the fecal samples. These findings suggest that T. gondii infection significantly impacts gut microbiota composition and diversity in stray cats. Additionally, an increased potential pathogen load, represented by Escherichia spp., was observed. These results underscore the importance of monitoring the prevalence of zoonotic pathogens in stray cats, as they can serve as reservoirs for zoonotic diseases.

Chromogenic culture media complements diagnostic cytology in the visual identification of pathogenic skin bacteria in dogs and cats

In dogs and cats, bacterial skin infections (pyoderma and otitis externa) are a common cause for visiting the veterinary clinic. The most frequent skin pathogens are Staphylococcus pseudintermedius, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, often requiring different therapeutic antibiotic protocols. Unfavorably, existing diagnostics based on cytology cannot reveal bacterial species but only bacterial shapes such as cocci or rods. This microscopic limitation could be overcome by clinical translation of affordable chromogenic media, which enable species identification based on bacterial colonies growing in different colors and sizes. In this study, we determined how well inexperienced general veterinary clinicians identified bacterial pathogens from the skin and ears on two commercial (Chromatic™ MH and Flexicult® Vet) and one custom-made Mueller Hinton agar-based chromogenic medium. For this purpose, four veterinarians evaluated 100 unique samples representing 10 bacterial species. On average, clinicians correctly identified between 72.1 and 86.3% of bacterial species. Colony colors developed quickly on the Chromatic™ MH medium, leading to the highest 81.6% identification accuracy after 24 h incubation. However, Flexicult® Vet exhibited the highest accuracy of 86.3% after prolonged 48 h incubation. Evaluators easily recognized bacteria displaying uniquely colored colonies like green-brown Pseudomonas aeruginosa, blue Enterococcus faecalis, orange-brown Proteus spp., and red Escherichia coli. Oppositely, staphylococci shared uncharacteristically pale pink colonies causing misidentifications among the genus, deteriorating overall accuracy by around 10 percentage points (from 90.9%). Another reason for identification errors was the evaluators' inexperience, reflected in not recognizing colony size differences. For example, although Streptococcus canis exhibited the tiniest colonies, the species was frequently mistaken for other cocci. Finally, around 10% of errors were negligence-related slips due to unconsidered sample history. To conclude, the introduction of chromogenic media into veterinary clinics can significantly complement diagnostics in skin inflammations by identifying pathogen species in around 80% of cases. The extra information may help in therapeutic dilemmas on antibiotics and standard antimicrobial susceptibility testing. Additional personnel training and evaluation help by visuals, flowcharts, checklists, and, if necessary, microbiologists could further improve identification accuracy.

Prevalence and Characterization of Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolated from Dogs and Cats in South Korea

Overall, 836 Escherichia coli isolates (695 isolates from dogs and 141 from cats) were recovered from the diarrhea, skin/ear, urine, and genitals of dogs and cats between 2018 and 2019. Cefovecin and enrofloxacin resistance were noted in 17.1% and 21.2% of E. coli isolates, respectively. The cefovecin and enrofloxacin resistance rates were higher in dog isolates (18.1% and 22.9%) compared with the rates in cat isolates (12.1%, 12.8%). Interestingly, resistance to both antimicrobials was noted in 10.8% (90/836) of the isolates, predominantly in isolates from dogs. bla_CTX-M-14, bla_CTX-M-15, and bla_CMY-2 were the most frequent extended-spectrum β-lactamase/plasmid-mediated AmpC β-lactamase (ESBL/AmpC)- gene types. The co-existence of bla_{CTX-M and}bla_CMY-2 was noted in six E. coli isolates from dogs. Sequencing analysis demonstrated that S83L and D87N in gyrA and S80I in parC were the most frequent point mutations in the quinolone resistance-determining regions of the cefovecin and enrofloxacin-resistant isolates. A total of 11 isolates from dogs carried the plasmid-mediated quinolone resistance genes (six aac(6')-Ib-cr, four qnrS, and one qnrB), while only two cat isolates carried the qnrS gene. Multilocus sequence typing of the cefovecin and enrofloxacin-resistant isolates revealed that sequence type (ST)131 E. coli carrying bla_CTX-M-14 and bla_CTX-M-15 genes and ST405 E. coli carrying bla_CMY-2 gene were predominant among the isolated E. coli strains. The majority of the ESBL/AmpC-producing isolates displayed diverse pulsed-field gel electrophoresis profiles. This study demonstrated that third-generation cephalosporin- and fluoroquinolone-resistant E. coli were widely distributed in companion animals. The detection of the pandemic ST131 clone carrying bla_CTX-M-_14/15 in companion animals presented a public health threat.

A pharmacodynamic investigation to assess the synergism of orbifloxacin and propyl gallate against Escherichia coli

Escherichia coli (E. coli) infections are becoming increasingly difficult to treat, as antibiotic-resistant variants proliferate. Studies on novel methods to combat the spread of resistance and improve the performance of current antibiotics are vital. We aimed to boost the efficacy of the antibiotic orbifloxacin (ORB) against E. coli by combining it with a phenolic component, propyl gallate (PG). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ORB against the E. coli KVCC 1423 resistant strain were 128 μg/ml and 256 μg/ml, respectively. However, the MIC of ORB for the remaining E. coli strains was 0.5 μg/ml–2 μg/ml. For the combination of PG and ORB, the lowest fractional inhibitory concentration (FIC) index was less than 0.5, and the combination decreased the MIC of both drugs by 74%. The time-kill assay revealed the killing properties of both the drugs and the pharmacodynamic model (PD model) confirmed the strong killing properties of the combination as compared to the individual activities of the drugs. The ratio between MIC and mutant prevention concentration of ORB against E. coli 1400306 and 1,423 were 1:32 and 1:8, respectively. The combination of ORB and PG showed strong biofilm eradication and inhibited the motility of bacteria. The cell viability of the combination was > 80%. Therefore, we believe that ORB and PG in combination could be a possible antibacterial candidate that could minimize resistance and improve antibiotic potential.

Bacterial Prevalence in Skin, Urine, Diarrheal Stool, and Respiratory Samples from Dogs

The emergence of bacterial infections in companion animals is a growing concern as humans can also be infected through the transmission of pathogenic bacteria. Because there have been few studies conducted on companion animals, the extent and significance of prevalence in veterinary practices remain unknown. This is the first nationwide surveillance report aimed at elucidating the prevalence pattern and associated infections of isolated bacteria from dogs in Korea. Bacterial isolates were collected from seven different laboratories participating in the Korean Veterinary Antimicrobial Resistance Monitoring System from 2018 to 2019. The samples were obtained from the diarrheal stool, skin/ear, urine, and respiratory samples of veterinary hospital-visited dogs. Isolation and identification of bacterial species was carried out using a bacterial culture approach and then confirmed with matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF) and polymerase chain reaction (PCR). Out of 3135 isolates in dogs, 1085, 1761, 171, and 118 were extracted from diarrheal stool, skin/ear, urine, and respiratory samples, respectively. The overall prevalence of bacteria was higher among two age groups (1-5 and 6-10 years) with a 66.5 percent prevalence. This study showed that Escherichia coli was the most prevalent species among isolated bacterial species of diarrheal and urine origin, whereas Staphylococcus pseudintermedius was the most prevalent among skin and respiratory sample isolates. The data on the prevalence of bacteria for each dog specimen could provide basic information to estimate the extent of bacterial infection and antimicrobial resistance development and to guide veterinarians in therapeutic decisions in clinical practices throughout Korea.