Surgical Wound Infection Rates in Dogs and Cats Data from a Teaching Hospital

Two thousand sixty-three surgical procedures were performed on 1992 patients (1715 dogs and 277 cats). In a retrospective analysis, the procedures were categorized according to the expected degree of wound contamination, and corresponding wound infection rates were determined. The number of procedures in each category and the percent that became infected were as follows: clean (1100, 2.5%), clean-contaminated (554, 4.5%), contaminated (172, 5.8%), and dirty (237, 18.1%). The administration of antibiotics significantly reduced the frequency of wound infection in clean surgical procedures performed by senior veterinary students (p less than 0.05), but not in clean elective procedures performed by faculty or resident surgeons that required 90 minutes or less to complete. There was a significant correlation between elevation of rectal temperature postoperatively and increased duration of the surgical procedure. However, the rectal temperature measured the day after surgery was not an accurate predictor of wound infection.     

Efficacy of Adhesive Incise Drapes in Preventing Bacterial Contamination of Clean Canine Surgical Wounds

Objective— To investigate the efficacy of adhesive incise drapes in reducing bacterial contamination of clean canine surgical wounds.
Study Design— Randomized clinical trial.
Animals— Dogs (n=100) having elective ovariohysterectomy or stifle surgery.
Methods— Dogs were randomly assigned to 1 of 2 groups: drape or no drape. Swabs obtained from the inner edge of the surgical wound at the beginning (swab 1) and end (swab 2) of surgery were submitted for microbial culture. Number of colony forming units was counted for all positive cultures and change in bacterial counts between swabs 1 and 2 was calculated. Percentage adhesive drape adherence at the end of surgery was calculated from a digital photograph of the surgical site. Duration of surgery/anesthesia and the anesthetic induction agent used were recorded.
Results— There was a significant increase in bacterial counts between swabs 1 and 2 ( P =.001). Wound contamination was 14% (6 drape; 8 no drape; P =0.78) with Staphylococcus spp. most commonly isolated. Median percentage drape adherence at the end of surgery was 89.3% (0–100%). Duration of anesthesia was significantly related to wound contamination ( P =.013), but duration of surgery and anesthesia induction agent were not.
Conclusions— Adhesive incise drapes did not reduce wound contamination of clean canine surgical wounds.
Clinical Relevance— Use of adhesive incise drapes in clean surgical procedures is of questionable benefit in dogs.     

Epidemiologic evaluation of postoperative wound infection in clean-contaminated wounds: A retrospective study of 239 dogs and cats

OBJECTIVE: To evaluate risk factors for development of postoperative wound infections in clean-contaminated wounds. STUDY DESIGN: Retrospective clinical study. SAMPLE POPULATION: Two hundred thirty-nine dogs and cats that had clean-contaminated surgical procedures. METHODS: Records of animals that had a clean-contaminated surgical procedure and were prospectively monitored for development of postoperative wound infection were reviewed. Prospective data included signalment, nutritional status, body weight, duration of surgery, surgical procedures, wound classification, surgical site clip time before surgery, hypotension during surgery, the presence of an active distant infection, endocrinopathy, administration of an immunosuppressive agent, administration of antibiotics, and the type of antibiotic used. Additional retrieved data included total anesthesia time, temperature variables, blood loss, and suture material used. RESULTS: Intact males (P =.008) and animals with concurrent endocrinopathy (P =.008) were at a higher risk of development of postoperative wound infection. Total surgery time (P =.02) and total anesthesia time (P =.04) were longer in animals that developed postoperative wound infection. No other factors were statistically significant. CONCLUSIONS: Intact males and animals with a concurrent endocrinopathy were at higher risk of postoperative wound infection after clean-contaminated surgical procedures. CLINICAL RELEVANCE: Time under anesthesia and duration of surgery should be minimized to reduce the risk of wound infection in clean-contaminated surgical procedures.     

Postoperative infection with Actinobacillus spp in horses: 10 cases (1995-2000)

OBJECTIVE: To determine features of postoperative wound infection caused by Actinobacillus spp in horses undergoing clean, elective surgery and to evaluate bacterial susceptibility profiles of bacteria isolated. DESIGN: Retrospective study. ANIMALS: 10 horses. PROCEDURE: Data were retrieved from medical records and the microbiology laboratory database. RESULTS: 1,604 horses underwent clean, elective surgical procedures during the study period. Of these, 23 (1.43%) had postoperative wound infections, and Actinobacillus spp was isolated from 10 of these 23 (43%). Surgical procedures in these 10 horses included laryngoplasty with ventriculocordectomy (n = 3), arthroscopy (3), desmotomy of the accessory ligament of the superficial digital flexor tendon (2), removal of laryngoplasty prostheses (1), and hygroma resection (1). Seven horses survived, and 3 were euthanatized. All 10 Actinobacillus isolates were resistant to penicillin, and 6 were resistant to trimethoprim-sulfamethoxazole. All isolates were susceptible to ceftiofur and gentamicin. During the 5-year period of the study, Actinobacillus organisms were isolated from 35 of 513 (6.8%) samples from the general hospital population submitted for bacterial culture and antimicrobial susceptibility testing. CONCLUSIONS AND CLINICAL RELEVANCE: During the study period, Actinobacillus spp was isolated from a higher than expected percentage of horses that developed postoperative wound infections after clean, elective surgery. Susceptibility profiles for these isolates were different from typical susceptibility profiles for Actinobacillus isolates, suggesting that a pattern of resistance may be emerging.     

The Association of Propofol Usage With Postoperative Wound Infection Rate in Clean Wounds: A Retrospective Study

OBJECTIVE: To determine if the use of propofol influences the postoperative infection rate of clean surgical wounds in dogs and cats. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: 863 dogs and cats undergoing clean surgical procedures. METHODS: Medical and anesthetic records of surgical cases used as part of a previously described epidemiologic study on postoperative wound infection rates were reviewed. The records of all animals with clean surgical wounds were reviewed to determine if propofol had been used for anesthetic induction or maintenance during the procedure. To determine the effect of propofol use on wound infection rate, data were analyzed using Fisher's exact test, followed by multiple logistic regression to adjust for various factors, including surgery time, time from clipping to surgery, antibiotic usage, coexisting distant infection, endocrine disease, and the use of immunosuppressive drugs in the perioperative period. RESULTS AND CONCLUSIONS: Of 863 dogs and cats with clean surgical wounds, 46 received propofol as part of the anesthetic protocol. A total of 6 of 46 animals (13%) receiving propofol developed postoperative wound infections, compared with 33 of 817 animals (4%) not receiving propofol (P = .014; % difference = 9%; 95% CI = 0.5% to 24%). Adjusting for all other factors evaluated, animals receiving propofol were 3.8 times more likely to develop postoperative wound infections compared to animals not given propofol (95% CI = 1.5-9.9). CLINICAL IMPLICATIONS: Propofol is a lipid-based emulsion capable of supporting microbial growth. Administration of a potentially contaminated solution may contribute to surgical wound infection or other patient morbidity or mortality. Strict aseptic technique in the preparation of the solution and prompt disposal of unused drug are imperative to curtail the potential for extrinsic contamination.     

Monitoring of microbial contamination of stick wound in swine carcasses

This study was done to evaluate the microbial contamination by Salmonella spp., Escherichia coli, fecal coliforms, and total aerobic count of the stick wound of swine carcasses. The effectiveness of trimming the stick wound in the 2 Québec slaughterhouses visited was evaluated. A bacteriological analysis was done on 276 stick wounds. Results indicated that, before trimming, 0.9% stick wounds were contaminated by Salmonella spp. Contamination by coliforms was observed in 40.6% of samples, and 27.7% were positive for E. coli. After trimming the stick wounds, 1.1% were contaminated by Salmonella spp., 34.1% were contaminated by coliforms, and 26.2% were positive for E. coli. The results showed that trimming contributes to reducing significantly the bacterial total count at the site and that the bacterial load at this site was less important than that found on the brisket.     

The effects of perioperative hypothermia and the duration of anesthesia on postoperative wound infection rate in clean wounds: a retrospective study

OBJECTIVE: To determine the effects of hypothermia and duration of anesthesia on the infection rate in clean wounds in dogs and cats. STUDY DESIGN: Retrospective clinical study. SAMPLE POPULATION: Seven hundred seventy-seven dogs and cats undergoing clean surgical procedures. METHODS: Records of animals prospectively evaluated for postoperative wound infection were retrospectively evaluated for the prevalence of perioperative hypothermia. Body temperatures during the perioperative period and the duration of surgery and anesthesia were recorded. Data were analyzed to identify differences between animals with infected and uninfected wounds and multiple logistic regression modeling was used to evaluate the independent contribution of risk factors to the incidence of postoperative wound infection. RESULTS: No statistically significant differences were found in the analysis of temperature data between animals with infected and uninfected wounds. Duration of anesthesia was significantly greater in animals with wound infections (P = .01). Multiple logistic regression modeling identified duration of anesthesia as a risk factor for postoperative wound infection independent of the duration of surgery. CONCLUSIONS: In animals with clean surgical wounds, mild perioperative hypothermia is not a significant risk factor for postoperative wound infection. The duration of anesthesia, however, is a significant risk factor independent of the duration of surgery. CLINICAL RELEVANCE: To decrease the incidence of postoperative wound infection, the duration of anesthesia should be minimized. Surgical time, as well as the time required for ancillary diagnostic tests while under anesthesia should, therefore, be kept to a reasonable minimum.     

Bacterial contamination of commercial ear cleaners following routine home use

Ear cleaning solutions are designed for repeated use, which raises the possibility for bacterial contamination leading to recurrent or persistent infectious otitis. The purpose of this study was to investigate the prevalence of bacterial contamination of commercial ear cleaners following routine home use in dogs and to describe the characteristics that are associated with contamination. Used ear cleaner bottles and information regarding their use were obtained from canine owners visiting veterinary dermatologists. Both the bottle applicator tips and the solution contents were cultured for aerobic bacteria. Bacterial contamination was present on 10% of the bottle tips and in 2% of the solutions. Isolated bacteria included Staphylococcus pseudintermedius, Bacillus spp., coagulase-negative Staphylococcus spp., Micrococcus spp. and Burkholderia cepacia. The contamination rate was significantly higher on the applicator tips than in the solutions (P = 0.0076). The applicator tip contamination rate was significantly higher in expired samples (17%) than in-date samples (4%; P = 0.0277). The bottle sizes were significantly larger for the samples with contaminated applicator tips compared with noncontaminated tips (P = 0.0455). The contamination rate was significantly higher when Tris-EDTA was an ingredient. Cleanliness of the bottle, contact with the ear canal and infection status of the ear at time of culture had no bearing on the contamination rate. In summary, with routine home use of commercial ear cleaners, pathogenic bacterial contamination is of minor concern. This concern may increase when expired products or larger bottles of ear cleaner are used and when Tris-EDTA is an ingredient.     

Evaluation of bacterial contamination on surgical drapes following use of the Bair Hugger? forced air warming system

This pilot study determined the rate of bacterial contamination on surgical drapes of small animal patients warmed intra-operatively with the Bair Hugger^® forced air warming system compared to a control method. Surgical drapes of 100 patients undergoing clean surgical procedures were swabbed with aerobic culturettes at the beginning and end of surgery. Samples were cultured on Trypticase soy agar. Contamination of the surgical drapes was identified in 6/98 cases (6.1%). There was no significant difference in the number of contaminated surgical drapes between the Bair Hugger^® and control groups (P = 0.47).     

In vitro efficacy of a polyhexamethylene biguanide-impregnated gauze dressing against bacteria found in veterinary patients

OBJECTIVE: To evaluate the in vitro efficacy of polyhexamethylene biguanide (PHMB)-impregnated gauze dressing in limiting the growth of bacteria both within and underneath the dressing. STUDY DESIGN: In vitro study. METHODS: Squares of PHMB-impregnated and control gauze were placed on agar plates inoculated with 1 of 11 bacterial species, including 8 multi-resistant organisms. Growth under the gauze was assessed qualitatively after 24-hour incubation. Repeated use of sponges was used to evaluate residual inhibitory activity against Micrococcus lutea and Staphylococcus schleiferi ss. schleiferi. In a second procedure, PHMB-impregnated and control gauze squares were placed in sterile plastic wells and inoculated with 1 of 5 bacterial species, including Pseudomonas spp. and Klebsiella spp. Inhibition of bacterial growth within and underneath the dressing after 24-hour incubation was evaluated by quantifying the numbers of bacteria on the well floor and within each square. RESULTS: PHMB-impregnated gauze provided greater inhibition of growth of 4/4 Gram-positive species and 2/6 Gram-negative species on inoculated plates compared with control gauze. Residual inhibitory activity of PHMB-impregnated gauze was significantly greater against M. lutea on all days and against S. schleiferi ss. schleiferi on days 1 and 4 compared with control. No bacteria were recovered from inoculated PHMB-impregnated gauze squares placed in sterile wells or from the well floor underneath. More than 9 x 10(5) colony-forming units (CFU) were recovered from inoculated control samples placed in sterile wells and more than 8.4 x 10(4) CFU were recovered from control well floors. CONCLUSION: PHMB-impregnated gauze dressing, when placed on inoculated agar plates, reduces growth of underlying bacteria, particularly Gram-positive species. Wet-inoculated PHMB-impregnated dressing prevents growth of Gram-positive and Gram-negative bacteria both within and underneath the dressing. CLINICAL RELEVANCE: PHMB-impregnated dressings may be useful for reducing contamination of underlying wounds by bacterial pathogens.     

Dog-bite wounds: bacteriology and treatment outcome in 37 cases

Bite wounds in 37 dogs were prospectively evaluated. Ninety-five percent of animals presented within 12 hours of injury. The most common wound locations were neck, limbs, head, chest, shoulder region, and abdomen. Eighty-six percent had wounds to multiple locations. Fifty-seven percent of wounds were Class 4 (i.e., most severe). Based on results of all samples, 65% had positive aerobic cultures, 15% had positive anaerobic cultures, and 33% had negative cultures. The most commonly isolated aerobic bacteria were Staphylococcus intermedius, Enterococcus spp., Staphylococcus coagulase negative, and Escherichia coli. Most common anaerobic isolates were Bacillus spp., Clostridium spp., and Corynebacterium spp. Severe bite wounds had a high rate of bacterial contamination at presentation. No single antibiotic or antibiotic combination was effective against all bacteria that were cultured.     

The bacteriology and antimicrobial susceptibility of infected and non-infected dog bite wounds: fifty cases

Dog bite wounds are a common reason for dogs requiring veterinary care, but there is surprisingly little data on the bacteriology of bite wounds. A prospective study was performed on dogs with various grades of bite wound to identify the bacteria present in these wounds. Swabs were collected from all wounds for bacterial culture and cytology. All swabs were cultured aerobically and anaerobically and all aerobic cultures were evaluated for antibiotic susceptibility using the Kirby Bauer disk diffusion test. Fifty dogs with 104 bite wounds, inflicted within the previous 72h, were included. The victims were predominately intact male small breed dogs. Of the 104 wounds, 21 were judged by cytology to be infected and 83 non-infected. Infected wounds were significantly more likely to culture positive (p=0.02). Sixteen percent of wounds showed no growth. Sixteen percent grew aerobes, 1% anaerobes and 67% a mixture of aerobes and anaerobes. Pasteurella canis and pyogenic streptococci were common in infected wounds, whereas Bacillus spp., Actinomyces spp. and the oral streptococci were usually found in contaminated wounds. Three anaerobic genera were cultured, namely, Prevotella, Clostridium and Peptostreptococcus. One case represented the first isolation of Capnocytophaga canimorsus in an infected dog bite wound. Although no single antibiotic therapy was considered to be effective against all the bacteria, amoxycillin plus clavulanic acid, 1st and 3rd generation cephalosporins ampicillin or amoxycillin and potentiated sulphonamides gave the best in vitro sensitivity results.     

Survey of Intraoperative Bacterial Contamination in Dogs Undergoing Elective Orthopedic Surgery

Objective

To investigate the frequency, source, and risk factors of intraoperative (IO) surgeon and patient bacterial contamination during clean orthopedic surgeries, and to investigate the relationship between IO contamination and surgical site infection (SSI) in dogs.

Study Design

Prospective clinical study.

Sample Population

Client‐owned dogs undergoing stifle surgery (n = 100).

Methods

IO cultures were taken in each case from surgical foot wrap, peri‐incisional skin, surgical gloves, and the surgical team's hands. The environment (operating room [OR] lights, computers, scrub sink faucet, anesthesia gurney, and radiology table) was sampled every 5 months. Bacteria were identified and the contamination of each case was categorized. All gloves from the surgical team were collected and tested for perforations using a water infusion test. Cases were followed for at least 8 weeks to determine the presence or absence of SSI. Perioperative variables were evaluated for association with IO contamination and SSI.

Results

Bacterial isolates were yielded from 81% of procedures from 1 or more sources; 58% had positive hand cultures, 46% had positive glove cultures, 23% had positive patient skin cultures, and 12% had positive foot wrap cultures. Staphylococcus spp. was the most commonly recovered bacteria. There was no apparent association between IO contamination and SSI. The highest level of environmental contamination was associated with the scrub sink faucet, followed by the radiology table, anesthesia gurney, and OR computers. The IO glove perforation rate was 18%.

Conclusion

Clean orthopedic procedures commonly had clinically insignificant bacterial contamination. In our study, bacteria responsible for SSI did not appear to colonize the patient in the OR.     

Chlorhexidine Gluconate Versus Chloroxylenol for Preoperative Skin Preparation in Dogs

The efficacy of 3% chloroxylenol (PCMX) or 4% chlorhexidine gluconate (CG) for preoperative skin preparation was assessed in 100 dogs undergoing clean or clean-contaminated surgical procedures. Replication Organism Detection and Counting (RODAC) plates were used to quantify skin bacteria colony forming units (CFU) at the operative site before and after skin preparation and immediately postoperatively. Reduction of CFU after skin preparation and immediately postoperatively was significant for each agent. However, CFU levels were significantly lower in the CG group than in the PCMX group after surgical preparation, regardless of initial CFU numbers. No significant difference in CFU counts was observed between antiseptic groups postoperatively. Within-group comparisons showed PCMX to be significantly less efficacious when the prescrub CFU number was greater than 1,000. Bacterial reduction was similar in the CG group regardless of prescrub CFU levels. The number of negative cultures after skin preparation was significantly greater with CG than with PCMX. Chlorhexidine gluconate also had fewer cultures with heavy bacterial growth (>5 CFUs) after surgical preparation. There was no significant difference between antiseptics in the number of negative cultures or cultures with more than 5 CFUs immediately after surgery. The number of skin reactions and postoperative wound infections that occurred with each technique were similar. Three percent PCMX, as used in this study, was less effective than 4% CG in its immediate antimicrobial activity, however, this difference was not associated with an increased wound infection rate.     

The antimicrobial activity of honey against common equine wound bacterial isolates

Delayed healing associated with distal limb wounds is a particular problem in equine clinical practice. Recent studies in human beings and other species have demonstrated the beneficial wound healing properties of honey, and medical grade honey dressings are available commercially in equine practice. Equine clinicians are reported to source other non-medical grade honeys for the same purpose. This study aimed to assess the antimicrobial activity of a number of honey types against common equine wound bacterial pathogens. Twenty-nine honey products were sourced, including gamma-irradiated and non-irradiated commercial medical grade honeys, supermarket honeys, and honeys from local beekeepers. To exclude contaminated honeys from the project, all honeys were cultured aerobically for evidence of bacterial contamination. Aerobic bacteria or fungi were recovered from 18 products. The antimicrobial activity of the remaining 11 products was assessed against 10 wound bacteria, recovered from the wounds of horses, including methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa. Eight products were effective against all 10 bacterial isolates at concentrations varying from <2% to 16% (v/v). Overall, the Scottish Heather Honey was the best performing product, and inhibited the growth of all 10 bacterial isolates at concentrations ranging from <2% to 6% (v/v).Although Manuka has been the most studied honey to date, other sources may have valuable antimicrobial properties. Since some honeys were found to be contaminated with aerobic bacteria or fungi, non-sterile honeys may not be suitable for wound treatment. Further assessment of gamma-irradiated honeys from the best performing honeys would be useful.     

Evaluation of arthrocentesis site bacterial flora before and after 4 methods of preparation in horses with and without evidence of skin contamination

OBJECTIVE: To evaluate the effectiveness of four methods of povidone-iodine preparation on skin bacterial flora of arthrocentesis sites, in horses, with and without evidence of skin contamination. STUDY DESIGN: Prospective randomized study. ANIMALS: Twenty-four adult horses. METHODS: Horses were assigned to either the clean or contaminated group based on housing environment and visual evidence of contamination. Using a moist sterile swab, microbial culture samples were obtained from the skin over the distal interphalangeal joints immediately before and after preparation. Each site was aseptically prepared with 1 of 4 povidone-iodine techniques: 10-minutes scrub, 5-minutes scrub, three 30-second scrubs, or commercial one-step iodophor surgical solution. Colony forming units (CFUs) were determined for each sample, 24 hours after inoculation, on blood agar plates. RESULTS: Mean (+/-SD) pre-scrub CFUs/mL was significantly higher in the contaminated group (9588.33+/-1223.65) compared with the clean group (4489.00+/-3842.03) (P<.01). After preparation of the arthrocentesis sites, there were no significant differences in post-scrub CFUs/mL among the 10 minutes (mean clean, 46.00+/-64.36; mean contaminated, 28.67+/-18.04), 5 minutes (mean clean, 84.17+/-109.80; mean contaminated, 40.33+/-44.52), three 30 seconds povidone-iodine scrubs (mean clean, 95.50+/-172.29; mean contaminated, 46.67+/-56.94), or application of a commercial one-step iodophor surgical solution (mean clean, 102.17+/-161.78; mean contaminated 117.67+/-143.78); or between the clean (81.96+/-131.69) and contaminated groups (58.33+/-85.90) (P<.01). CONCLUSIONS: Preparation of the distal interphalangeal joint arthrocentesis site with each of these techniques significantly reduces the bacterial flora to a similar level for arthrocentesis in horses with and without evidence of skin contamination. Clinical Relevance- Aseptic preparation of the skin over the distal interphalangeal joint may be accomplished with any of these techniques.     

The distribution of pathogens and their antimicrobial susceptibility patterns among canine surgical wound infections in Sweden in relation to different risk factors

Background

Surgical site infection (SSI) is a common nosocomial infection in dogs and a growing concern in veterinary hospitals as an increase in multidrug-resistant pathogens is reported. Despite the need for rational and prudent antimicrobial use, few peer-reviewed and published veterinary studies have investigated the pathogenic growth including susceptibility patterns of the isolated pathogens in canine SSIs.The first objective of the present study was to estimate the distribution of bacterial pathogens in dogs with SSI and to investigate whether this was influenced by type of surgical procedure (clean, clean-contaminated, contaminated or dirty), duration of hospitalization, wound classification and depth of the infection, or antimicrobial treatment. The second objective was to assess susceptibility patterns to clinically relevant antimicrobials.During three years, four animal referral hospitals and three small animal clinics submitted bacterial swabs from canine SSIs for culture and susceptibility, together with a questionnaire completed by the attending clinician.

Results

Approximately two thirds of the in total 194 isolates were staphylococci. Staphylococcus pseudintermedius was the most prevalent finding (46%) followed by beta haemolytic Streptococcus spp. (24%). No associations between distribution of the isolated pathogens and classification of the surgical procedure, duration of hospitalization or depth of the SSI were shown, with the exception of Escherichia coli isolates being significantly more often found in deep wound infections than in superficial skin infections.Overall the possibilities of finding first generations antimicrobials to treat the SSIs included in the study were favorable, as the isolated pathogens were mostly without acquired antimicrobial resistance and multidrug resistance was uncommon. There were only three cases of methicillin-resistant S. pseudintermedius-infections (one percent of all isolates), one case of extended-spectrum beta-lactamase producing E. coli-infection, and no methicillin-resistant Staphylococcus aureus infections.

Conclusions

None of the investigated factors were shown to influence the distribution of bacterial pathogens. The majority of SSIs were caused by staphylococci, and S. pseudintermedius was the most prevalent pathogen. Based on the study results, use of first-line antimicrobials prior to receiving culture and susceptibility results is a rational empirical antimicrobial therapy for the studied dog population.     

Bacterial contamination of colostrum fed to newborn calves in Québec dairy herds

A convenience sample of 234 colostral specimens, collected directly from the nursing bottle immediately prior to the first feeding, was studied. Samples originated from 6 farms and were collected over 24 months. Routine bacteriologic techniques were used to quantify the bacterial load of the colostrum, as well as to identify the bacteria. Overall, at least 1 microorganism was cultured from 221 colostral samples (94.4%). By using the upper tolerance level of 100,000 bacteria/mL, 84 samples (35.9%) were considered contaminated. Staphylococcus spp. (57.7%), gram-negative rods (47.9%), coliforms (44.0%), and Streptococcus uberis (20.5%) were among the most frequently isolated bacteria. The relative risk (RR) of contamination with more than 100,000 bacteria/mL was significantly greater in warm months [RR = 2.55, 95% confidence interval (CI): 1.63 to 4.02] than in cool months and in colostrum offered to male calves (RR = 1.55, 95% CI: 1.09 to 2.20). Bacterial load was also associated with the farm of origin (P < 0.0001). When assessing colostrum management, one should consider bacterial contamination. Multiple factors are likely associated with the degree of contamination, and farm-specific factors may be important. Further studies are necessary to evaluate the impact of bacterial contamination of colostrum on neonatal health.     

Microbiology of equine wounds and evidence of bacterial biofilms

Horse wounds have a high risk of becoming infected due to their environment. Infected wounds harbour diverse populations of microorganisms, however in some cases these microorganisms can be difficult to identify and fail to respond to antibiotic treatment, resulting in chronic non-healing wounds. In human wounds this has been attributed to the ability of bacteria to survive in a biofilm phenotypic state. Biofilms are known to delay wound healing, principally due to their recalcitrance towards antimicrobial therapies and components of the innate immune response. This study describes the presence of bacterial biofilms within equine wounds. Thirteen 8-mm diameter tissue samples were collected from (n=18) chronic wounds. Following histological staining, samples were observed for evidence of biofilms. Fifty one wounds and control skin sites were sampled using sterile swabs. Control skin sites were on the uninjured side of the horse at the same anatomical location as the wound. The isolated bacteria were cultured aerobically and anaerobically. The biofilm forming potential of all the isolated bacteria was determined using a standard crystal violet microtitre plate assay. Stained tissue samples provided evidence of biofilms within 61.5% (8 out of 13) equine wounds. In total 340 bacterial isolates were identified from all the equine wound and skin samples. Pseudomonas aeruginosa and Enterococcus faecium were the most predominantly isolated bacterial species from equine wound and skin samples respectively. Staphylococcus was the most commonly isolated genus in both environments. Bacteria cultured from chronic and acute wounds showed significantly (P<0.05) higher biofilm forming potential than bacteria isolated from skin. This paper highlights preliminary evidence supporting the presence of biofilms and a high microbial diversity in equine chronic wounds. The presence of biofilms in equine wounds partly explains the reluctance of many lower limb wounds to heal. Non-healing limb wounds in horses are a well documented welfare and economic concern. This knowledge can be used to shape future treatments in order to increase the healing rate and decrease the costs and suffering associate with equine wounds.     

A Comparison of Antimicrobial Efficacy and Tissue Reaction of Four Antiseptics on Canine Wounds

Three concentrations of povidone iodine, chlorhexidine, benzalkonium chloride, and a pluronic polyol were tested for antimicrobial efficacy and tissue reaction in wounds inoculated with Staphyloccocus aureus .
Five paired incisions were created on the back of each of 16 dogs in four treatment groups. Five wounds were inoculated with beta-hemolytic, coagulase positive S. aureus (10⁹ organisms); the contralateral wounds were not inoculated. After two hours, three wounds on each side were irrigated with antiseptic in low, medium, or high concentrations; another was irrigated with physiological saline; and one was left untreated. One hundred ml of solution was applied in each instance with a syringe and needle at approximately 8 psi.
Tissue bacteria were quantitated immediately following irrigation. The wounds were sutured with 5/0 monofilament stainless steel and bandaged. After 48 hours, the dogs were euthanized and signs of wound infection were recorded. Wound bacteria were quantitated again, and sections of the wounds were removed for examination by light microscopy.
Antiseptics were significantly effective (p < 0.01) in reducing the bacterial population in contaminated wounds when compared to control wounds on the same dog. High antiseptic concentrations were more effective than low concentrations. At 48 hours, the bacterial population was significantly lower in wounds treated with chlorhexidine or benzalkonium chloride compared with povidone iodine or pluronic polyol. The antiseptics caused no significant difference (p < 0.01) in tissue reaction in noninoculated wounds. Chlorhexidine (0.5 or 1.0%) was the most effective antiseptic under the conditions used.