Prevalence of coagulase-positive methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius in dogs in Bangladesh

Virulence genes and antibiotic resistance profiling of staphylococcus species isolated from mastitic dairy cows in and around Bahir dar, Ethiopia

BACKGROUND

Mastitis is one of the primary causes of economic and production losses in the dairy cattle industry. Bacterial infections are the most significant contributors to bovine mastitis, with Staphylococcus species among the most prevalent and challenging pathogens. This issue is especially severe in low- and middle-income countries, including Ethiopia, where a comprehensive understanding of Staphylococcus species in clinical and subclinical mastitis remains poorly understood. This is particularly true in the regions surrounding Bahir Dar, where comprehensive data on the genetic determinants of virulence and resistance in Staphylococcus species causing bovine mastitis are notably lacking. The lack of such molecular insights hampers the development of targeted therapeutic and preventive strategies for managing mastitis in the region. Therefore, the present study aimed to investigate the virulence gene profiles and antimicrobial resistance (AMR) patterns of Staphylococcus species isolated from mastitic dairy cows in and around Bahir Dar, Ethiopia.

METHODOLOGY

A cross-sectional study was conducted from March 2023 to December 2023 to investigate the molecular characteristics of Staphylococcus species and their antimicrobial resistance profiles in dairy cows with mastitis. A total of 150 lactating cows from 21 farms were included in the study, with 600 milk samples collected from the four-quarters of each cow. The samples were screened via the California mastitis test and physical examination. Staphylococcus species isolates were identified and single-plex PCR was used to detect virulence genes. The antimicrobial resistance profile of the isolates was determined via the Kary-Bauer disk diffusion method.

RESULTS

The overall quarter-level mastitis incidence was 19.83% (119/600). Among 119 mastitis-positive samples, 80 samples were bacteriologically confirmed to harbor Staphylococcus species with eight different Staphylococcus species, of which Staphylococcus chromogenes was the most prevalent isolate (19%), followed by S. aureus, S. hyicus and S. epidermidis (15%), S. hemolyticus (11%), S. simulans and S. xylosus (10%), and S. intermedius (5%). Seven distinct virulence genes were identified with varying frequencies: Coa (35%), seb (33.33%), mecA (31.67%), icaD (31.67%), Hla (20%), Hlb (10%), and sea (8.3%). The icaD and seb genes were observed in all 8 species with respective percentages (S. hemolyticus (62.5, 37.5), S. aureus (44.44, 55.55), S. hyicus (44.44, 44.44), S. epidermidis 2 (22.22, 44.44), chromogenes (9.1, 9.1), S. intermidius (33.33, 33.33), S. simulance (16.67, 16.67) and S. xylosus (16.67, 16.67). Both the Hla and Hlb genes were detected in the same three distinct species, with percentages of S. aureus (44.44; 22.22%), S. hemolyticus (42.5; 25%) and S. hyicus (55.55; 22.22). S. aureus exhibited the highest proportion of mecA-positive isolates, with 6 out of 9 isolates (66.67%) carrying the gene. All the isolated Staphylococcus species were 100% resistant to penicillin, and except for S. chromogenes and S. xylosus, the remaining 6 species of Staphylococcus also exhibited 100% resistance to tetracycline. Among all MDR isolates, 6/9 (66.7%) S. aureus, (5/8; 62.5%) S. hemolyticus, and (6/9; 66.7%) S. hyicus were resistant to up to seven classes of antibiotics. A lower frequency of MDR isolates was detected among S. simulans and S. xylosus (both at 2/6; 33.33%), resistant to up to five antibiotics.

CONCLUSIONS

Among the identified Staphylococcus species, S. chromogenes emerged as the dominant isolate. All eight isolated species harbored two or more virulence genes, with nearly one-third of the isolates carrying the mecA gene, underscoring their pathogenic potential in causing bovine mastitis. Furthermore, all the Staphylococcus isolates in this study were resistant to penicillin and were multidrug resistant.

Genotypic profile of Staphylococcus spp., Enterococcus spp., and E. coli colonizing dogs, surgeons, and environment during the intraoperative period: a cross-sectional study in a veterinary teaching hospital in Brazil

AIMS

This prospective cross-sectional study aimed to determine the occurrence of resistance genes and genetic diversity in Staphylococcus spp., Enterococcus spp., and Escherichia coli isolated from dogs' superficial surgical site (SS), surgeons' hands, and the operating room (OR) during the intraoperative period.

METHODS

Thirty dogs undergoing clean/clean-contaminated (G1, n = 20) and contaminated surgeries (G2, n = 10), along with eight surgeons, were included in the study. Specimens were collected using sterile swabs, transported in 0.1% peptone salt solution, and spread onto blood agar. Environmental samples were collected through passive exposure using BHI agar plates. Seventy-five isolates were selected and classified using MALDI-TOF MS. Resistance genes were screened via PCR: tet(M), ermA, aacA-aphD, blaZ, mecA, blaTEM-1, blaSHV, blaSHV-1, blaCTX-M-1, 3 e 15, blaCTX-M-2, blaCMY-2, mcr1, mcr2, mcr3, mcr4, and ndm. Genetic diversity was assessed through PFGE analysis using SmaI and XbaI restriction enzymes, with clustering performed by the UPGMA method. The chi-square test compared the frequency of resistance gene detected.

RESULTS

Staphylococcus pseudintermedius (83.33%), Enterococcus spp. (52.63%), and E. coli (62.50%) were more frequently isolated from dogs' skin, while coagulase-negative staphylococci (CoNS; 62.50%) were more frequent in the OR. Resistance genes detected in Staphylococcus spp. included blaZ (79.17%), mecA (43.75%), tet(M) (41.67%), and aacA-aphD (25%). Among Enterococcus spp., tet(M) (78.95%) and blaZ (10.53%) were identified. S. pseudintermedius harbored tet(M) and aacA-aphD genes more frequently than CoNS. No E. coli isolates tested positive for the investigated genes. Twenty-four PFGE banding patterns were observed in CoNS (24/24), 15 in S. pseudintermedius (15/24), 4 in E. coli (4/8), and 7 in Enterococcus spp. (7/19). Genetically related S. pseudintermedius and E. coli were obtained from SS and OR in G2. Seven indistinguishable Enterococcus spp. were identified across different procedures and patients.

CONCLUSION

Our study revealed high rates of methicillin-resistant Staphylococcus spp. and tetracycline-resistant Enterococcus spp. colonizing the environment in a veterinary teaching hospital in Brazil. PFGE analysis indicated a high diversity of CoNS and Enterococcus spp. Genetically related strains in S. pseudintermedius, Enterococcus spp., and E. coli emphasize the importance of effective infection control policies to minimize the spread of resistant bacteria.

Novel hydroxy naphthol blue-based recombinase polymerase amplification for the rapid detection of Staphylococcus pseudintermedius

Staphylococcus pseudintermedius (S. pseudintermedius) is a significant cause of pyoderma, soft tissue, urinary tract, and ear infections in cats and dogs. Bacterial culture and biochemical phenotypic assays are the gold standards for clinical diagnosis of bacteria but molecular methods have now been developed to identify and differentiate S. pseudintermedius. However, these methods require complex and expensive equipment, restricting usage in many laboratories. This study developed a rapid, specific, and sensitive detection method for S. pseudintermedius based on recombinase polymerase amplification (RPA) combined with hydroxy naphthol blue (HNB) dye. The RPA primer was designed, optimized, and subjected to amplify the spsL gene as the molecular diagnostic target. HNB dye was added to the reaction, successfully enabling the development of a colorimetric detection method for S. pseudintermedius. This RPA-HNB assay completed amplification at 37 °C within 20 min, with results visualized by the naked eye as a color change. All processes were completed within an hour. The assay showed the limit of detection at 1 copy per reaction, with sensitivity and specificity against S. pseudintermedius 0.98 and 1.00, respectively. Results indicated that our assay provided high sensitivity and specificity for detecting S. pseudintermedius with reduced detection time.

Antimicrobial Resistance Profiles and mupA Gene Characterization of Staphylococcus epidermidis Recovered from Facial Skin of Healthy Females in Shanghai, China

Purpose

To explore antimicrobial resistance profiles and mupA gene characterization of Staphylococcus epidermidis recovered from facial skin of healthy females in Shanghai, China.

Patients and Methods

In this study, we collected facial skin samples from 107 healthy females in Shanghai, China, and S. epidermidis isolation was performed. The minimal inhibitory concentrations of 10 antibiotics were determined for the S. epidermidis isolates using the agar dilution method. High-level mupirocin-resistant isolates were subjected to whole-genome sequencing and bioinformatics analysis. A total of 94 un-duplicated S. epidermidis isolates were obtained from 107 facial skin samples.

Results

Antimicrobial susceptibility tests revealed that 23.4% of the 94 S. epidermidis isolates were resistant to oxacillin and positive for the mecA gene, which could be cauterized as methicillin-resistant S. epidermidis (MRSE). Resistance rates for erythromycin, clindamycin, tetracycline, ciprofloxacin, and gentamicin were 8.5%, 11.7%, 10.6%, 12.8%, and 1.1%, respectively. For mupirocin, the rates of low- and high-level resistance were 3.2% (3/94) and 11.7% (11/94), respectively. Resistance to vancomycin or linezolid was not observed. High-level mupirocin resistance in facial skin isolates is mediated by mupA. WGS and SNP-based phylogenetic analyses revealed diverse phylogenies among the 11 mupA-positive S. epidermidis isolates. Additionally, various resistance and virulence genes were identified in mupA-positive isolates. A new hybrid plasmid carrying mupA genes was found in two S. epidermidis isolates.

Conclusion

We observed a considerable level of antimicrobial resistance to several antibiotics and the prevalence of abundant and diverse resistance and virulence genes in the facial skin-origin S. epidermidis isolates. This may pose a potential risk for both public health and S. epidermidis infection.

Antimicrobial resistance and virulence profiling of Staphylococcus pseudintermedius isolated from cats, Bangladesh

Staphylococcus pseudintermedius is a significant bacterial pathogen that frequently colonizes different body sites and mucous membranes of pets. The objectives of the cross-sectional study were to estimate the prevalence, antimicrobial resistance pattern, and detection of diverse resistance as well as virulence genes of S. pseudintermedius in cats. A standard bacteriological method, species-specific gene and different antimicrobial resistance as well as virulence genes were confirmed by PCR assay. A total of 233 swab samples were collected from different body sites of 102 cats, among them 146 swabs from 73 healthy cats, and 87 from 29 diseased cats. Overall, prevalence of S. pseudintermedius in cats was 12.01%, while dermatitis and otitis affected cats were 26.08% and 33.33%, respectively. The highest antimicrobial resistance was observed against penicillin (96.42%) followed by streptomycin (85.71%) and erythromycin (78.57%). Moreover, 89.28% of S. pseudintermedius isolates exhibit multi-drug resistance (MDR) (≥ 3 classes' antimicrobial resistant). In addition, 17.86% isolates harbored the mecA gene; thus, were classified as methicillin-resistant S. pseudintermedius (MRSP). Furthermore, the erythromycin resistance genes ermA and ermB were harbored by 25% and 10.71% of isolates, while 42.86% and 17.86% of isolates carried tetK and tetL (tetracycline resistance) genes, respectively. In virulence profiling, 32.14% (sea) and 10.71% (seb) of isolates were found positive for enterotoxin genes, whereas, the toxic shock syndrome toxin-1 (tst-1) gene and the Panton-Valentine leukocidin gene (pvl) were detected in 25% and 14.29% of isolates, respectively. To our knowledge, this is the first report of cats in Bangladesh for MDR S. pseudintermedius, MRSP, and their virulence profiling.

Isolation and antimicrobial resistance patterns of Staphylococcus aureus and Escherichia coli from caprine respiratory tract infections: A hospital-based clinical study

Objective

Staphylococcus aureus and Escherichia coli are the most common opportunistic pathogens frequently associated with respiratory tract infection (RTI) in different animals. This cross-sectional study aimed to identify the occurrence of S. aureus and E. coli in goats with RTI, analyze the antimicrobial resistance patterns, and explore potential risk factors contributing to RTI.

Materials and Methods

A total of 120 nasal swab samples were collected from goats, and standard classical bacteriological methods were performed to isolate and identify S. aureus and E. coli. Subsequently, the disc diffusion method was employed to evaluate the antimicrobial sensitivity test. A logistic regression model was used to analyze the factors associated with RTI.

Results

About 13.3% (N = 16; N = 120) isolates were confirmed as S. aureus, and 6.67% (N = 8; N = 120) isolates were confirmed as E. coli. All S. aureus isolates were resistant to ampicillin, and all E. coli isolates were resistant to amoxicillin and penicillin. Among the isolated organisms, 43.7% (N = 7; N = 16) S. aureus and 62.5% (N = 5; N = 8) E. coli isolates were found to be multidrug-resistant (resistant to ≥3 classes of antimicrobials). Multivariable logistic regression analysis revealed that female goats [(odds ratio) OR: 4.2; 95% confidence intervals (CI): 0.8-20.8; p = 0.074] and goats in poor health condition (OR: 3.8; 95% CI: 0.7-19.3; p = 0.100) were more prone to RTI caused by S. aureus. Besides, goats that were not dewormed (OR: 4.8; 95% CI: 1-23.6; p = 0.051) and those reared in semi-intensive conditions (OR: 2.7; 95% CI: 0.8-8.7; p = 0.092) were found to be at higher risk of S. aureus-mediated RTI.

Conclusion

The findings highlight the importance of implementing improved farm management practices and efficient antimicrobial resistance control approaches to minimize respiratory infections and reduce the burden of antibiotic resistance in goats.

Staphylococcus pseudintermedius and Pseudomonas aeruginosa Lubbock Chronic Wound Biofilm (LCWB): a suitable dual-species model for in vitro studies

Antimicrobial treatment of methicillin-resistant Staphylococcus pseudintermedius associated with canine wounds represents an important challenge. The aim of this study was to create a canine wound infection model, Lubbock Chronic Wound Biofilm (LCWB), with a focus on S. pseudintermedius, drawing inspiration from the established human model involving Staphylococcus aureus. Methicillin-resistant S. pseudintermedius 115 (MRSP) and Pseudomonas aeruginosa 700 strains, isolated from dog wounds, were used to set up the LCWB at 24, 48 and 72 h. The LCWBs were evaluated in terms of volume, weight, and microbial CFU/mg. The microbial spatial distribution in the LCWBs was assessed by SEM and CLSM imaging. The best incubation time for the LCWB production in terms of volume (3.38 cm3 ± 0.13), weight (0.86 gr ± 0.02) and CFU/mg (up to 7.05 × 106 CFU/mg ± 2.89 × 105) was 48 h. The SEM and CLSM images showed a major viable microbial colonization at 48 h with non-mixed bacteria with a prevalence of MRSP on the surface and P. aeruginosa 700 in the depth of the wound. The obtained findings demonstrate the capability of S. pseudintermedius to grow together P. aeruginosa in the LCWB model, representing the suitable model to reproduce the animal chronic wound in vitro.

Antimicrobial resistance, enterotoxin and biofilm production genes in Staphylococcus spp. isolated from facilities and fomites in veterinary hospital in the Caatinga biome

The Caatinga biome occurs only in Brazil and offers epidemiological conditions that should be assessed differently from other regions of Brazil and the world. Thus, the aim of this survey was to identify antimicrobial resistance, enterotoxin and biofilm production genes in Staphylococcus spp. isolated from facilities and fomites in a veterinary hospital in Caatinga biome. Samples were collected from surfaces of small animal clinical care tables (n =8), cages in the dog and cat hospitalisation sector and animals with infectious diseases (n = 21), small animal surgical centre (n =8), sterilisation sector (n =7) and stethoscopes (n = 32) by using sterile swabs. Bacterial isolation and identification, antimicrobial resistance phenotypic test and molecular detection of antimicrobial resistance, biofilm formation and enterotoxin genes were carried out. Ninety-five bacterial isolates were obtained, and 29 (30.5%) were identified as Staphylococcus spp. Overall, 13 isolates (44.8%) of six species of Staphylococcus spp. showed antimicrobial resistance profile, as well as S. haemolyticus expressed phenotypic profile of multidrug resistance. The antimicrobials with the highest resistance rates were penicillin and tetracycline. The most frequent resistance genes were blaZ and tetM, both detected in 10 (76.9%) isolates. The mecA, tetL and tetK genes had frequencies of 38.5% (5/13), 23.1% (3/13) and 15.4% (2/13), respectively. The biofilm production marker, icaD gene, was detected in one S. sciuri strain. SEE gene, which encodes enterotoxins, was detected in 15.4% (2/13) of the strains (S. pseudintermedius and S. intermedius). The occurrence of Staphylococcus spp. carrying resistance genes to diferent classes of antimicrobials, presenting MDR phenotypic pattern and carrying enterotoxins and biofim encoding genes recovered from veterinary hospital facilities and fomites in the Caatinga biome reinforce the need to implement prevention cares in veterinary practices to avoid One Health-concerning conditions.

Integrating multi-wet laboratory diagnostics to study staphylococci in animals in Uganda

BACKGROUND

Several diagnostic environments in Uganda lack real-time, robust and high-throughput technologies for comprehensive typing of microbes, which is a setback to infectious disease surveillance. This study combined various wet laboratory diagnostics to understand the epidemiology of pathogenic staphylococci isolated from animals in Uganda and the implications for global health security priorities.

METHODS

A retrospective study was conducted employing records and pathogenic staphylococci (from animals) archived at the Central Diagnostic Laboratory (CDL), Makerere University, Uganda, between January 2012 and December 2019. The bacteria were speciated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and tested for virulence factors [beta lactamases, lecithinase, deoxyribonuclease (DNase), haemolysins] and resistance to ten antimicrobials of clinical and veterinary relevance. Tetracycline and methicillin resistance genes were also tested.

RESULTS

The prevalent diseases were mastitis in cattle and skin infections in dogs. Of the 111 staphylococci tested by MALDI-TOF MS, 79 (71.2%) were Staphylococcus aureus, 27 (24.3%) were Staphylococcus pseudintermedius and 5 (4.5%) were Staphylococcus schleiferi. All these strains expressed haemolysins. The prevalence of strains with lecithinase, penicillinase, cephalosporinase and DNase was 35.9% (14/39), 89.7% (35/39), 0.0% (0/39) and 87.2% (34/39), respectively. Staphylococci were primarily resistant to early penicillins (over 80%), tetracycline (57.7%), and chloramphenicol (46.2%). Minimal resistance was noted with cloxacillin (0.0%), ciprofloxacin (9.6%), and cefoxitin (3.8%). The prevalence of multidrug resistance (MDR) was 78.8% for general staphylococci, 82.2% for S. aureus, 73.1% for S. pseudintermedius, and 60.0% for S. schleiferi. Multidrug resistant staphylococci were significantly more prevalent in the cattle isolates than in the dog isolates (P < 0.05). The prevalence of methicillin-resistant staphylococci (MRS) tested by resistance to cefoxitin and mecA carriage was 3.8%. These four strains were all isolated from dog skin infections. The tetK gene was the most predominant (35.4%), followed by tetM (25.0%).

CONCLUSION

In resource-constrained settings, the approach of integrated diagnostics promises sustainable disease surveillance and the addressing of current capacity gaps. The emergence of MRS (zoonotic bacteria) in companion animals creates a likelihood of reduced treatment options for related human infections, a threat to global health.

Prevalence and anti-microbial resistance of Staphylococcus spp. isolated from the environment and veterinary personnel in a Spanish veterinary teaching hospital

Methicillin-resistant Staphylococcus (MRS) bacteria, including methicillin-resistant S. aureus and methicillin-resistant S. pseudintermedius (MRSP), pose a significant threat in veterinary medicine, given their potential for zoonotic transmission and their implications for companion animals and humans' health. This study aimed to assess the prevalence of MRS and anti-microbial resistance patterns at a university clinical hospital in Madrid, Spain. Samples were collected from both the environment and hospital staff at Veterinary Clinical Hospital of Alfonso X el Sabio University. Anti-microbial susceptibility assays, molecular detection of mecA gene and genetic relationships among the identified bacterial strains were performed. The study revealed an MRS prevalence of 1.50% in environmental samples, with MRSP accounting for 0.75% of the cases. Genetically related MRSP strains were found in different hospital areas. Among hospital staff, there was a MRS prevalence of 14.03%, including S. pseudintermedius and S. epidermidis strains. Antibiogram tests revealed multi-drug resistance among MRSP strains. Additionally, methicillin-resistant coagulase-negative staphylococci were isolated, suggesting potential cross-species transmission. This study underscores the presence of MRS in a veterinary clinical hospital, highlighting the significance of infection control through the implementation of protective measures, stringent hygiene practices among personnel and in the environment and responsible use of antibiotics. Further research is necessary to assess MRS incidence in animal patients and explore geographical variations, enhancing our understanding of MRS in veterinary medicine and addressing its challenges.

Molecular identification, antimicrobial resistance and virulence gene profiling of Staphylococcus spp. associated with bovine sub-clinical mastitis in Bangladesh

This study was conducted to investigate the diversity and antimicrobial resistance profiling of Staphylococcus species causing sub-clinical mastitis (SCM) in dairy herds in Bangladesh as well as putative risk factors associated with the infections. Individual quarter milk samples were collected from a total of 284 lactating cows from 30 dairy farms were screened by means of California mastitis test; 178 (62.7%) of them had at least of quarter affected by SCM. After conventional microbiological isolation procedures, PCR tests were used for Staphylococcus species identification and detection of antimicrobial resistance and virulence genes. S. chromogenes (65.7%) was the most predominant species followed by, S. epidermidis (20.2%), S. haemolyticus (19.1%), S. aureus (15.7%), and S. sciuri (5.6%). High levels of antimicrobial resistance to ampicillin and amoxicillin/clavulanic acid were observed in S. aureus (82.1% and 75%) and S. sciuri (80% and 70%), while resistance to cefepime was markedly higher in S. chromogenes (95.7%), S. haemolyticus (94.1%), and S. epidermidis (97.2%). Multidrug resistance isolates were identified in all five species. The mecA gene was detected in S. aureus (32.1%) and S. chromogenes (5.98%). In addition, 20% S. sciuri and 17.7% S. haemolyticus carried the cytotoxin (pvl) gene, while 14.3% S. aureus harbored the toxic shock syndrome toxin (tst) gene. Multivariable logistic regression analysis identified "Old aged" (OR [CI]: 3.5 [1-12.4]); "Early stage of lactation" (OR [CI]: 3.4 [1.2-9.7]) and, "Firm udder condition" (OR [CI]: 4.2 [1.2-14.6]) as risk factors associated with SCM caused by S. aureus, S. chromogenes, and S. haemolyticus, respectively. Moreover, "Use of antimicrobials" (OR [CI]: 10.4 [3.4-32.1] and "History of previous clinical mastitis" (OR [CI]: 4.9 [1.2-19.7] for the carriage of methicillin-resistant Staphylococcus spp.

Comparative Susceptibility of Pathogenic Methicillin-Resistant and Methicillin-Susceptible Staphylococcus pseudintermedius to Empirical Cotrimazole for Canine Pyoderma

The prevalence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) that causes pyoderma has been gradually shifting, according to many surveillance studies, with annual changes. The empirical cotrimazole regimen remains interesting, but research on cotrimazole susceptibility to MRSP is limited. The objective of this study was to evaluate the susceptibility of cotrimazole to canine pyoderma MRSP isolates. Sixty isolates of S. pseudintermedius were identified as 16 MRSP and 44 methicillin-susceptible S. pseudintermedius (MSSP) using an oxacillin disk diffusion test and VITEK 2 system with VITEK GP card. Using the VITEK 2 system with a VITEK AST-GP81 card, the susceptibility rates of MRSP (15.00%) and MSSP (35.00%) to cotrimazole was observed. The median MIC of cotrimazole on MSSP (median, ≤10; IQR, 10-320) was lower than that of MRSP (median, ≥320; IQR, 10-320) (p = 0.5889, Mann-Whitney test). Percent attainment of PK/PD targets in MRSP (q 12 h, 43.75; q 8 h, 43.75) were lower than that of MSSP (q 12 h, 52.27; q 8 h, 52.27) (p = 0.7710). These findings show the moderately phenotypic cotrimazole susceptibilities of both MRSP and MSSP. Further study is required to develop clinical trials examining the use of cotrimazole in dogs with pyoderma.

Effects of Piper betle Extracts against Biofilm Formation by Methicillin-Resistant Staphylococcus pseudintermedius Isolated from Dogs

Emergence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) isolated from dogs with cutaneous and wound infections has significantly impacted veterinary medicine. This study aimed to isolate S. pseudintermedius from canine pyoderma and investigate the effects of ethanolic extracts of Piper betle (PB), P. sarmentosum (PS), and P. nigrum (PN) on the bacterial growth and biofilm formation of S. pseudintermedius and MRSP. Of the isolated 152 isolates, 53 were identified as S. pseudintermedius using polymerase chain reaction, and 10 isolates (6.58%) were identified as MRSP based on the presence of mecA. Based on phenotype, 90% of MRSPs were multidrug-resistant. All MRSP had moderate (10%, 1/10) and strong (90%, 9/10) biofilm production ability. PB extracts were the most effective in inhibiting planktonic cells, and the minimum inhibitory concentration at which ≥50% of the isolates were inhibited (MIC₅₀) was 256 µg/mL (256-1024 µg/mL) for S. pseudintermedius isolates and 512 µg/mL (256-1024 µg/mL) for MRSP isolates. The MIC₉₀ for S. pseudintermedius and MRSP was 512 µg/mL. In XTT assay, PB at 4× MIC showed an inhibition rate of 39.66-68.90% and 45.58-59.13% for S. pseudintermedius and MRSP, respectively, in inhibiting biofilm formation. For PB at 8× MIC, the inhibition rates for S. pseudintermedius and MRSP were 50.74-81.66% and 59.57-78.33%, respectively. Further, 18 compounds were identified in PB using gas chromatography-mass spectrometry, and hydroxychavicol (36.02%) was the major constituent. These results indicated that PB could inhibit bacteria growth of and biofilm formation by S. pseudintermedius and MRSP isolated from canine pyoderma in a concentration-dependent manner. Therefore, PB is a potential candidate for the treatment of MRSP infection and biofilm formation in veterinary medicine.

Prevalence of mecA, mecC and Panton-Valentine-Leukocidin Genes in Clinical Isolates of Coagulase Positive Staphylococci from Dermatological Canine Patients

Coagulase positive Staphylococci (CoPS) are the leading cause of canine cutaneous and otic infections. Virulence factors associated with Staphylococci include the expression of mec and panton-valentine leukocidin (pvl) genes. Methicillin-resistance (MR) is commonly associated with mecA gene expression, although a recently identified variant, mecC, has been reported. This study aims to evaluate the prevalence of mecA, mecC and pvl genes in 232 clinical isolates of CoPS collected from dogs with pyoderma. A multiplex PCR, and Kirby-Bauer disk diffusion susceptibility test for cefoxitin was performed for all isolates. PBP2a agglutination test was performed on 127 isolates. Standard MRSA isolates were used as positive controls. The mecA gene was identified in 149/232 isolates (64.2%): 116 S. pseudintermedius, 30 S. coagulans and three S. aureus. The pvl gene was present in only 1 isolate of S. pseudintermedius (0.4%), whereas no isolates carried the mecC gene. 34 isolates were resistant to cefoxitin (14.6%) and they were all mecA positive. The results of this study show an MR prevalence of 64.2% confirming concerns about antibiotic resistance in veterinary medicine. In conclusion, this is the first study analyzing the prevalence of mecC and pvl in comparison to mecA, in a large cohort of CoPS clinical isolates from dogs with pyoderma. A multimodal surveillance on the prevalence of mecC and pvl in veterinary medicine is essential to appropriate antimicrobial management.

Antibiotic resistance, biofilm formation, and virulence factors of isolates of staphylococcus pseudintermedius from healthy dogs and dogs with keratitis

Canine bacterial keratitis is a common infection that can potentially threaten vision. Staphylococcus pseudintermedius (S. pseudintermedius) is an opportunistic pathogen that has been isolated from the canine conjunctival sac but there are only a few reports on the role of this bacterium in canine keratitis. This study focused on the distribution rate of S. pseudintermedius in the canine conjunctival sac, and the antibiotic resistance, biofilm-producing ability, and dissemination of virulence factors in strains of S. pseudintermedius isolated from healthy dogs and dogs with keratitis. The study included 35 healthy dogs and 40 dogs with keratitis. Bacterial species were confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI–TOF MS). Strains of S. pseudintermedius were screened for resistance against nine different antibiotics by the Kirby–Bauer assay. The ability to produce biofilm was investigated by microtiter plate assay (MtP) and amplification of icaA and icaD genes. Virulence factors in the strains were also evaluated. A total of 132 aerobic bacteria were isolated from the 119 samples in the study. Among them, 67 bacterial strains were isolated from 70 eyes of healthy dogs, and 65 bacterial strains were isolated from 49 eyes of dogs with keratitis. The prevalence of S. pseudintermedius, which was the most frequent bacterial isolate in both the groups, was 20.9% in the healthy group and 23.08% in the keratitis group. Most of the isolates of S. pseudintermedius were sensitive to rifampin (96.6%), oxacillin (100%), and neomycin (96.6%), and resistant to tetracycline (96.6%). Virulence factors such as lip (96.6%), hlgB (96.6%), and hlgA (96.6%) were found in most of the isolates, and 89.66% of isolates were classed as biofilm producers. In conclusion, S. pseudintermedius was the common bacterium in the conjunctivital sac of the healthy dogs and dogs with keratitis in Yangzhou, China, and the presence of virulence factors and biofilm-formation ability were high in the strains isolated from the dogs with keratitis.