Dataset Information

Characterization of the biofilm forming ability of Staphylococcus pseudintermedius from dogs.

ABSTRACT:

Background

Staphylococcus pseudintermedius is an opportunistic pathogen of dogs and has emerged as a leading cause of skin, wound and surgical site infections worldwide. Methicillin resistance is common and clinical infections as a result of methicillin-resistant S. pseudintermedius (MRSP) pose a clinical challenge. In other staphylococci, biofilm formation has been shown to be a virulence factor for infection, however, it has received little attention in S. pseudintermedius. The objectives of this study were to evaluate the biofilm forming ability of clinical isolates of S. pseudintermedius obtained from dogs using phenotypic and genotypic techniques.

Results

96% (136/140) of S. pseudintermedius isolates were classified as strong or moderate biofilm producers, with the majority of isolates being able to produce biofilm. There was no difference in biofilm formation between MRSP and MSSP (p=0.8), amongst isolates from clinical infections compared with isolates obtained from colonized dogs (p=0.08), and between isolates from sequence type (ST) 71 and ST 68 (P=0.09). icaA was detected in 77.9% (109/140) of isolates and icaD was detected in 75.7% (106/140) of isolates. Scanning electron microscopic evaluation of S. pseudintermedius biofilm production revealed aggregates of cocci and irregularly produced extracellular polymeric matrix.

Conclusion

The majority of S. pseudintermedius isolates evaluated in this study were able to produce biofilm and this may be an important virulence factor in the rapid emergence of this bacterium in veterinary hospitals worldwide. Further study into the mechanisms of biofilm formation by S. pseudintermedius is warranted.

SUBMITTER: Singh A

PROVIDER: S-EPMC3681638 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

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Publications

Characterization of the biofilm forming ability of Staphylococcus pseudintermedius from dogs.

Singh Ameet A Walker Meagan M Rousseau Joyce J Weese Jeffrey Scott JS

BMC veterinary research 20130503

<h4>Background</h4>Staphylococcus pseudintermedius is an opportunistic pathogen of dogs and has emerged as a leading cause of skin, wound and surgical site infections worldwide. Methicillin resistance is common and clinical infections as a result of methicillin-resistant S. pseudintermedius (MRSP) pose a clinical challenge. In other staphylococci, biofilm formation has been shown to be a virulence factor for infection, however, it has received little attention in S. pseudintermedius. The objecti ...[more]

PMID: 23641755

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Project description:Staphylococcus pseudintermedius is an important canine pathogen implicated in an increasing number of human infections. Along with rising levels of methicillin and multidrug resistance, staphylococcal biofilms are a complicating factor for treatment and contribute to device, implant, and surgical infections. Staphylococcal virulence, including biofilm formation, is regulated in part by the quorum sensing accessory gene regulator system (agr). The signal molecule for agr, known as the autoinducing peptide molecule, contains polymorphisms that result in the formation of distinct groups. In S. pseudintermedius, 4 groups (i.e., groups I, II, III, and IV) have been identified but not comprehensively examined for associations with infection type, virulence factor carriage, or phylogenetic relationships-all of which have been found to be significant in S. aureus In this study, 160 clinical canine isolates from Texas, including isolates from healthy dogs (n?=?40) and 3 different infection groups (pyoderma, urinary tract, and surgical, n?=?40 each), were sequenced. The agr group, biofilm-producing capabilities, toxin gene carriage, antimicrobial resistance, and sequence type (ST) were identified for all isolates. While no significant associations were discovered among the clinical infection types and agr groups, agr II isolates were significantly less common than any other group in diseased dogs. Furthermore, agr II isolates were less likely than other agr groups to be multidrug resistant and to carry toxin genes expA and sec-canine Fifty-two (33%) of the 160 isolates were methicillin resistant, and the main sequence types (ST64, ST68, ST71, ST84, ST150, and ST155) of methicillin-resistant strains of S. pseudintermedius (MRSP) were identified for the geographic region.IMPORTANCE Staphylococcus pseudintermedius is an important disease-causing bacterium in dogs and is recognized as a growing threat to human health. Due to increasing multidrug resistance, discovery of alternative methods for treatment of these infections is vital. Interference with one target for alternative treatment, the quorum sensing system agr, has demonstrated clinical improvement of infections in S. aureus animal models. In this study, we sequenced and characterized 160 clinical S. pseudintermedius isolates and their agr systems in order to increase understanding of the epidemiology of the agr group and clarify its associations with types of infection and antimicrobial resistance. We found that isolates with agr type II were significantly less common than other agr types in diseased dogs. This provides valuable information to veterinary clinical microbiologists and clinicians, especially as less research has been performed on infection associations of agr and its therapeutic potential in S. pseudintermedius than in S. aureus.

Project description:BACKGROUND: Methicillin-resistant S. pseudintermedius strains (MRSP) are reported with increasing frequency in bacterial cultures from dogs. The objectives of this study were to determine whether MRSP could be found in dogs several months after a clinically apparent infection and whether the length of carriage varied depending on systemic antimicrobial treatment, diagnosis at time of the first positive MRSP culture and the presence of skin disease or wounds. Thirty-one dogs previously diagnosed with a clinical infection were sampled repeatedly for a minimum of eight months or, with the exception of two dogs, until two consecutive negative results were obtained. Five specified locations were sampled, and the results were evaluated to determine future recommendations concerning sample strategies when screening for MRSP carriage. Information was collected from medical records and questionnaires to evaluate factors that may influence length of carriage. RESULTS: The overall median length of MRSP carriage was 11 months (48 weeks). The presence of wounds and signs of dermatitis did not influence length of carriage. Systemic treatment for three weeks or longer with antimicrobial agents to which the bacterium was resistant was associated with prolonged carriage compared to dogs treated for a shorter period of time. Three of five dogs treated with an antimicrobial to which their MRSP-isolates were susceptible (tetracycline) were found to still be MRSP-positive when sampled after the end of treatment. Wound samples had the highest positive MRSP yield (81%) for the positive sample sites, compared to less than 70% for each of the other four sample sites. Cultures from the nostrils were less likely to detect MRSP carriage relative to the pharynx, perineum, wounds and the corner of the mouth. CONCLUSIONS: Dogs can carry MRSP for more than a year after a clinically apparent infection. Systemic antimicrobial treatment of infections with antimicrobial agents to which the MRSP-bacteria are resistant should be avoided when possible in dogs with possible or confirmed MRSP carriage or infection, since it may prolong time of MRSP carriage. Simultaneous sampling of pharynx, perineum, and the corner of the mouth as well as wounds when present is recommended when screening for MRSP. Cultures from nostrils were shown to be less likely to detect MRSP carriage.

Project description:Staphylococcus pseudintermedius is a commensal bacterium of the canine skin but is also a key opportunistic pathogen that is responsible for most cases of pyoderma in dogs. The current paradigm indicates that infection arises when predisposing factors alter the healthy skin barrier. Despite their importance, the characteristics of the S. pseudintermedius populations colonizing the skin of healthy dogs are yet largely unknown. Here, we retrieved 67 complete circular genomes and 19 associated plasmids from S. pseudintermedius isolated from the skin of 9 healthy dogs via long-reads Nanopore sequencing. Within the S. pseudintermedius populations isolated from healthy skin, multilocus sequence typing (MLST) detected 10 different STs, distributed mainly by the host. 39% of the 18 representative genomes isolated herein were methicillin-resistant S. pseudintermedius (MRSP), and they showed, on average, a higher number of antibiotic resistance genes and prophages than did the methicillin-sensitive (MSSP). In summary, our results revealed that the S. pseudintermedius populations inhabiting the skin of healthy dogs are relatively diverse and heterogeneous in terms of MLST and methicillin resistance. In this study, all of the 67 commensal S. pseudintermedius populations that were isolated from healthy dogs contained antibiotic resistance genes, indicating the extent and severity of the problem of antimicrobial resistance in staphylococci with zoonotic potential. IMPORTANCE Staphylococcus pseudintermedius is a commensal canine bacterium that can become an opportunistic pathogen and is responsible for most cases of canine pyoderma. It can also cause occasional zoonotic infections. Infections caused by antibiotic-resistant Staphylococcus are a global concern. Skin commensal Staphylococcus pseudintermedius is understudied. To provide insight into the commensal strains circulating in healthy dogs, we performed whole-genome sequencing of 67 S. pseudintermedius isolates from different skin sites in 9 healthy dogs. Through the bioinformatic analysis of these genomes, we identified a genomic diversity that is more complete than those afforded by traditional molecular typing strategies. We identified 7 new STs. All of the isolates harbored genes associated with antibiotic resistance, and 39% of the representative genomes were methicillin-resistant. Our data provide critical insights for future skin infection control and antibiotic surveillance within veterinary medicine.

Project description:Staphylococcus pseudintermedius is responsible for severe and necrotizing infections in humans and dogs. Contrary to S. aureus, the pathophysiological mechanisms involved in this virulence are incompletely understood. We previously showed the intracellular cytotoxicity induced after internalization of S. pseudintermedius. Herein, we aimed to identify the virulence factors responsible for this cytotoxic activity. After addition of filtered S. pseudintermedius supernatants in culture cell media, MG63 cells, used as representative of non-professional phagocytic cells (NPPc), released a high level of LDH, indicating that the cytotoxicity was mainly mediated by secreted factors. Accordingly, we focused our attention on S. pseudintermedius toxins. In silico analysis found the presence of two PSMs (?-toxin and PSM?) as well as Luk-I leukotoxin, the presence of which was confirmed by PCR in all clinical strains tested (n = 17). Recombinant Luk-I leukotoxin had no cytotoxic activity on NPPc but the ectopic expression of the CXCR2 receptor in U937 cells conferred cytotoxity to Luk-I. This is in agreement with the lack of Luk-I effect on NPPc and the previous report of Luk-I cytoxic activity on immune cells. Contrary to Luk-I, synthetic ?-toxin and PSM? had a strong cytotoxic activity on NPPc. The secretion of ?-toxin and PSM? at cytotoxic concentrations by S. pseudintermedius in culture supernatant was confirmed by HPLC-MS. In addition, the supplementation of such supernatants with human serum, known to inhibit PSM, induced a complete abolition of cytotoxicity which indicates that PSMs are the key players in the cytotoxic phenotype of NPPc. The results suggest that the severity of S. pseudintermedius infections is, at least in part, explained by a combined action of Luk-I that specifically targets immune cells expressing the CXCR2 receptor, and PSMs that disrupt cell membranes whatever the cell types. The present study strengthens the key role of PSMs in virulence of the different species belonging to Staphylococcus genus.

Dataset Information

Characterization of the biofilm forming ability of Staphylococcus pseudintermedius from dogs.

Background

Results

Conclusion

Publications

Characterization of the biofilm forming ability of Staphylococcus pseudintermedius from dogs.

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