Microbial profile of canine persistent wound infections

Aim: To analyse the microbial profile of canine persistent wound infections. Materials and Methods: The total wound samples (n=172) taken from both traumatic (140) and post-surgical (32) persistent wounds in canines were processed for routine microbial isolation and identification during a period of 15 months. Results: Staphylococcus intermedius was found to be the predominant isolate from all types of wounds under study. It was followed by Staphylococcus aureus, Pseudomonas aeruginosa, E. coli, Pasteurella spp., Corynaebacterium spp. and Bacillus spp. From different traumatic wounds of dogs, S. intermedius (92/140=65.7%) and from surgical wounds, P. aeruginosa (24/32=75%) were found to be the predominant isolates recovered whereas the most commonly isolated bacterial genus in both traumatic and surgical wounds of dogs was Staphylococcus spp. Conclusion: Canine wounds are polymicrobial in nature. Hence proper microbial laboratory diagnosis and presence of multiple organisms in a wound are to be taken into consideration for effective treatment of persistent wound infections in dogs.


Introduction
microbial profile of persistent wounds in dogs for their better managemental practices.Wounds can be classified as acute and chronic.The acute wounds either traumatic or surgical move

Materials and Methods
through the healing process at a predictable rate from

Ethical approval:
insult to closure but chronic wounds are not resolved over a reasonable period of time no matter the cause [1,2].In wounds, the presence of exposed subcutaneous Collection of sample: In order to analyse the microbial tissue provides a favourable substratum for a wide profile of canine persistent wound infections, dogs of variety of micro-organisms to contaminate and different age groups and breeds with various history of colonise.If the involved tissue is devitalised and the wounds of more than 16 days old infection, were host immune response is compromised, the conditions included in the study.The study was carried out in the become optimal for microbial growth [3].It is reported laboratory of Department of Veterinary Microbiology that more than 80% of persistent bacterial infections and Teaching Veterinary Clinical Complex (TVCC) in are likely to involve biofilms [4,5,6].The bacteria the college of Veterinary Science and Animal Husbandry, adhere to the surface of wound by attaching to the Orissa University of Agriculture and Technology, exposed extracellular matrix, multiply and develop in to microcolonies.These colonies aggregate in to larger Bhubaneswar in the period of March 2012-June 2013.groups known as Biofilms.These biofilms once esta-Two swabs for each sample were collected in sterile blished, resist the action of antimicrobials and evade way for duplicate cultures.A total of 140 samples were the host defense mechanism [7].The chronic wound collected from dogs having history like prolonged infections in dogs cause economic losses to pet owners nonhealing wounds originated from accidents, infected due to the cost of treatment for longer periods.For wounds like otitis, anal wound, mammary tumor assogreater understanding of wound ecology its microbial ciated wounds, gangrenous tail wounds and pyoderma.analysis is necessary which may allow for better Also 32 samples originated from post-surgical cases of management to facilitate wound healing.
ear haematoma, mandibular fracture and inguinal In the current study it was planned to evaluate the wounds were included in the study.Samples were processed for the aerobic bacterial culture by inoculating swabs in to TSB (Tryptone Soya Broth), The approval for collecting wound samples from dogs was taken from Instituitional Animal Ethics Committee.0 coli (41.3%),Pasteurella spp.(19.2%),Corynaebacand incubated at 37 C for 24 hrs for growth of bacteria.
isolates obtained are depicted in Figure -1.From different To isolate colonies for each types of bacteria present in types of wounds like accidental wound (n=37), culture, they were streaked and incubated on TSA localized anal wound (n=18), otitis (n=29), lacerated (Tryptone Soya Agar), as it provides enough nutrient mammary wound (n=11), gangrenous tail wound for wide variety of bacteria .Then colony morphology (n=14), pyoderma (n=31), post-surgical mandibular was noted and Gram staining of each type of colony wound (n=11), post-surgical ear haematoma wounds was done to confirm the morphological differences (n=13) and post-surgical inguinal wounds (n=8), S. among them.Bacteria from each type of colony were intermedius was isolated and identified in except gangrenous tail wounds where the P. obtained from HiMedia, Mumbai.[8].

Results
was found to be least in all the traumatic wounds except In the wound samples (n=172) collected from gangrenous tail wounds where Corynaebacterium spp.various types of wound infections of dogs, the was least predominant.In all the post-surgical wounds predominant isolate was found to be Staphylococcus P. aeruginosa was the major isolated pathogen whereas intermedius (63.4%).It was followed by Staphylococcus Pasteurella spp. in both post-surgical mandible aureus (51.2%),Pseudomonas aeruginosa (48.2%),E.
wounds and post-surgical inguinal wounds.Bacillus  spp. in post-surgical ear hematoma were found to be response [14].It has been reported that Staphylococcus least predominant.A great variation was obtained for serves as a major source of contamination during the bacteria isolated from different types of traumatic surgery [19] and S. aureus is encountered in 50% of wounds than that of post-surgical wounds.From orthopedic cases [20].different traumatic wounds, S. intermedius (92/140 But in the present study P. aeruginosa was the =65.7%) was found as predominant isolate.In postmajor isolates in both post-surgical and orthopedic surgical wounds, P. aeruginosa (24/32=75%) was the (mandibular wound) cases.This variation could be due to most predominant isolate recovered whereas the most our limited study focusing only on three types of postcommonly isolated genus in both traumatic and surgical surgical wounds.Among different traumatic wounds wounds of dogs was mostly of Staphylococcus.In all mixed infection was least in accidental wound and types of wounds both in traumatic and post-surgical more in gangrenous tail wound, which is chronic in wounds mixed infections were present.Among traumatic nature and always presented in delayed condition after wounds maximum mixed infection was observed in failure of primary treatment.Similarly, in post-surgical cases of gangrenous tail wounds whereas least mixed wounds, mixed infection was more in mandibular infection was in accidental wounds.Similarly in postwound because oral orthopedic wound always take surgical wounds, maximum and minimum mixed more time for healing and there is chance of more infections were observed in post-surgical mandible contamination and inability to maintain aseptic condition wound and post-surgical ear haematoma respectively.during healing period.In post-surgical ear hematoma cases less mixed infection was observed which might Discussion be due to presence of less soft tissue on ear pinna and The present study revealed that the isolates of S. more vascularity.As most wound infections involve intermedius, S. aureus, P. aeruginosa, E.coli, Pasteurella mixed populations of both aerobic and anaerobic spp., Corynaebacterium spp.and Bacillus spp.were micro-organisms [3,14], the complete microbial profile persistently causing wound infections in dogs.This of canine persistent wound infections can be obtained suggests that canine wounds are polymicrobial in nature after analyzing for anaerobes along with aerobes.and containing pathogens which are significantly However analysis for anaerobes could not be prevalent in chronic wounds.This agrees with the conducted in this study due to lack of facilities.findings of previous studies [3,9,10,11].It was reported

Conclusion
by Freeman et al that wounds are polymicrobial in nature in equines too.The study also showed that Total collected wound samples (n=172) from Staphylococcus found in synergistic relation with other persistent wound infections in dogs were processed for bacteria in infected wounds were mostly with E. coli isolation and identification which revealed that wound and P. aeruginosa.This shows similarity with the microbiology of dog is complex.The microbe S. finding of Thomas [13] in which it was reported that intermedius was found to be the most predominant bacteria like Staphylococcus never occurs singly and isolate in traumatic wounds and P. aeruginosa in postmostly found synergistically with other bacteria in surgical wounds.The Staphylococcus genus was found infected wounds.The synergism of bacteria might lead to be the most common isolate from both traumatic and to greater pathogenesis than individual inputs.In the post-surgical wounds.The other isolates obtained in present study, S. intermedius (65.7%) was found to be decreasing order of prevalence were E. coli, the most predominant isolate from traumatic wounds Pasteurella spp., Corynaebacterium spp.and Bacillus which is in accordance of the earlier works [14,15], spp.This suggests that the canine wounds are who reported that most prevalent bacteria was S.
polymicrobial in nature.The results reported in this intermedius in dog infected wounds and that it was the study may serve as a guide for further studies in the most common pathogen isolated in dogs having same species and may help the veterinarians for proper wounds arising due to dog bites .The increased microbial laboratory diagnosis and also for effective prevalence of S. intermedius might be due to its occurrence management of persistent wound infection in dogs.as commensal on skin and mucus membranes in dogs.

Figure- 1 :
Figure-1: Graph showing percentage of bacterial genera isolated from traumatic and post-surgical wounds.

Table - 1
: The prevalence of different bacteria species from canine infected wounds (n=172).