Clinical efficacy and safety of cefovecin in the treatment of canine pyoderma and wound infections

CEFOVECIN PROTEIN BINDING AS A PREDICTOR FOR EXTENDED DURATION OF ACTION: A REVIEW OF CURRENT LITERATURE AND IN VITRO ANALYSIS IN MULTIPLE ZOOLOGICAL SPECIES

Cefovecin is a third-generation cephalosporin antibiotic with an efficacy of 2 wk following a single injection in domestic dogs and cats. A high degree of plasma protein binding to cefovecin has been proposed as one of the mechanisms responsible for the long elimination half-life, but protein binding has not been evaluated extensively in nondomestic species. In this study, a review of the current literature was conducted, and pharmacokinetic data were compiled for species in which cefovecin has been evaluated thus far. Additionally, in vitro cefovecin protein binding was evaluated in plasma from 22 nondomestic species representing a broad range of taxa. Animals of the order Carnivora demonstrated protein-binding levels of >98%, which is supportive of the long elimination half-life seen in related species. Protein binding was highly variable in Artiodactyl and Perissodactyl species, with dolphins (Tursiops truncatus) and barasingha (Rucervus duvaucelii) displaying high protein binding (99.12% to >99%), but not gazelles (Eudorcas thomsonii) or equids (91.76-92.70%). Cefovecin was not highly bound in any reptiles or birds, corresponding to short half-lives reported for these taxa. These results suggest that a high percentage of plasma protein binding in vitro may predict in which species cefovecin may exhibit a long half-life and duration of action in vivo. These findings may aid in selecting species for cefovecin pharmacokinetic research and for empirical treatment of infections caused by susceptible bacteria.

The Complex Diseases of Staphylococcus pseudintermedius in Canines: Where to Next?

Staphylococcus pseudintermedius is a pathogenic bacterium of concern within the veterinary sector and is involved in numerous infections in canines, including topical infections such as canine pyoderma and otitis externa, as well as systemic infections within the urinary, respiratory and reproductive tract. The high prevalence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) within such infections is a growing concern. Therefore, it is crucial to understand the involvement of S. pseudintermedius in canine disease pathology to gain better insight into novel treatment avenues. Here, we review the literature focused on S. pseudintermedius infection in multiple anatomic locations in dogs and the role of MRSP in treatment outcomes at these niches. Multiple novel treatment avenues for MRSP have been pioneered in recent years and these are discussed with a specific focus on vaccines and phage therapy as potential therapeutic options. Whilst both undertakings are in their infancy, phage therapy is versatile and has shown high success in both animal and human medical use. It is clear that further research is required to combat the growing problems associated with MRSP in canines.

The Effectiveness of Fluorescent Light Energy as Adjunct Therapy in Canine Deep Pyoderma: A Randomized Clinical Trial

A single centre, single-blinded, prospective, randomized, controlled clinical study was conducted to evaluate the effectiveness of twice weekly fluorescent light energy therapy (Phovia™) as adjunct to systemic antibiotics in the management of deep pyoderma in dogs. Dogs with clinical lesions consistent with deep pyoderma, positive bacterial culture, and showing neutrophil engulfing bacteria at cytology were included in the study. Assessments were undertaken weekly for 8 weeks and every 2 weeks thereafter until 12 weeks after enrolment. At each visit, lesions were scored and cytology was conducted to determine a neutrophil engulfing bacteria score. All dogs (Groups A and B) were treated with systemic antibiotic twice daily, and Group B received additionally Phovia twice weekly. Median treatment duration was 11.7 weeks for Group A and 5.7 weeks for Group B. After 8 weeks of treatment, the percentage of dogs that achieved clinical resolution was 35.0% and 88.0% for Groups A and B, respectively. Lesion scores showed highly statistically significant difference in favour of Group B from week 3 to 8, and neutrophil engulfing bacteria scores showed statistical difference from week 2 onwards in favour of Group B. These results indicate that Phovia, when used as an adjunct to systemic antibiotics, can accelerate time to clinical resolution in cases of canine deep pyoderma.

In vitro killing of canine strains of Staphylococcus pseudintermedius and Escherichia coli by cefazolin, cefovecin, doxycycline and pradofloxacin over a range of bacterial densities

Background

Bacterial densities likely fluctuate during infection and may exceed the bacterial density used in susceptibility testing. As such, investigation of bacterial killing by antibiotics over a range of varying bacterial densities may provide important differences between compounds and could impact drug selection for therapy.

Hypothesis/Objectives

To measure killing of clinical isolates of Staphylococcus pseudintermedius and Escherichia coli by cefazolin, cefovecin, doxycycline and pradofloxacin at clinically relevant (minimum inhibitory, mutant prevention, maximum serum and maximum tissue) drug concentrations against varying densities of bacteria.

Animals/Materials

Bacterial strains collected from dogs with urinary tract infections were studied.

Methods and materials

High bacterial densities ranging from 10⁶ to 10⁹ colony forming units (cfu)/mL were exposed to minimum inhibitory, mutant prevention, blood and tissue drug concentrations, and the percentages (log₁₀) of viable cells killed following 30 min, 1, 2, 4, 6, 12 and 24 h of drug exposure were quantified.

Results

Doxycycline exhibited bacteriostatic properties with less killing than the other three agents. For example, at a 10⁷ cfu/mL density of S. pseudintermedius, more cells were killed by pradofloxacin (P < 0.0001) and cefovecin (P = 0.0014) but not cefazolin when compared to doxycycline at the maximum serum drug concentration following 12 h of drug exposure.

Conclusions and clinical importance

Differences were seen between some drugs in the speed and extent of bacterial killing; this could be clinically important and may impact drug selection and length of therapy.

Background – Bacterial densities likely fluctuate during infection and may exceed the bacterial density used in susceptibility testing. As such, investigation of bacterial killing by antibiotics over a range of varying bacterial densities may provide important differences between compounds and could impact drug selection for therapy. Hypothesis – To measure killing of clinical isolates of Staphylococcus pseudintermedius and Escherichia coli by cefazolin, cefovecin, doxycycline and pradofloxacin at clinically relevant (minimum inhibitory, mutant prevention, maximum serum and maximum tissue) drug concentrations against varying densities of bacteria. Conclusions and clinical importance – Differences were seen between some drugs in the speed and extent of bacterial killing; this could be clinically important and may impact drug selection and length of therapy.

Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases)

BACKGROUND

Superficial bacterial folliculitis (SBF) is usually caused by Staphylococcus pseudintermedius and routinely treated with systemic antimicrobial agents. Infection is a consequence of reduced immunity associated with alterations of the skin barrier and underlying diseases that may be difficult to diagnose and resolve; thus, SBF is frequently recurrent and repeated treatment is necessary. The emergence of multiresistant bacteria, particularly meticillin-resistant S. pseudintermedius (MRSP), has focused attention on the need for optimal management of SBF.

OBJECTIVES

Provision of an internationally available resource guiding practitioners in the diagnosis, treatment and prevention of SBF.

DEVELOPMENT OF THE GUIDELINES

The guidelines were developed by the Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases, with consultation and advice from diplomates of the American and European Colleges of Veterinary Dermatology. They describe optimal methods for the diagnosis and management of SBF, including isolation of the causative organism, antimicrobial susceptibility testing, selection of antimicrobial drugs, therapeutic protocols and advice on infection control. Guidance is given for topical and systemic modalities, including approaches suitable for MRSP. Systemic drugs are classified in three tiers. Tier one drugs are used when diagnosis is clear cut and risk factors for antimicrobial drug resistance are not present. Otherwise, tier two drugs are used and antimicrobial susceptibility tests are mandatory. Tier three includes drugs reserved for highly resistant infections; their use is strongly discouraged and, when necessary, they should be used in consultation with specialists.

CONCLUSIONS AND CLINICAL IMPORTANCE

Optimal management of SBF will improve antimicrobial use and reduce selection of MRSP and other multidrug-resistant bacteria affecting animal and human health.

Azithromycin pharmacokinetics in the serum and its distribution to the skin in healthy dogs and dogs with pyoderma

Serum and skin tissue azithromycin (AZM) concentrations were analysed in healthy and pyoderma affected dogs to determine AZM pharmacokinetics and to establish the effect of disease on AZM skin disposition. AZM was administered orally to two groups of healthy dogs: (1) at 7.02 mg/kg (n=7) and (2) at 11.2mg/kg (n=9). A crossover design was used on five of them. Seven dogs with pyoderma were treated with AZM at 10.7 mg/kg. The two groups of healthy dogs received AZM once daily over three consecutive days and dogs with pyoderma received the same treatment repeated twice with an interval of 1 week. AZM concentrations were determined by liquid chromatography-tandem mass spectrometry. AZM was rapidly absorbed and slowly excreted. In healthy dogs, maximum serum concentrations appeared 2h after administration and were (mean ± standard deviation) 0.60 ± 0.25 μg/mL and 1.03 ± 0.43 μg/mL, and the half-lives were 49.9 ± 5.10 and 51.9 ± 6.69 h for doses of 7.02 and 11.2mg/kg, respectively. Clearance (CL0-24/F) was similar in both dosing groups (1.24 ± 0.24 and 1.29 ± 0.24 L/h/kg) and the respective mean residence time (MRT0-24) was 11.1 ± 0.8 and 8.4 ± 2.2h. The skin concentration in healthy dogs was 3.5-6.5 and 5.0-12.0 times higher than the corresponding serum concentration after the two doses and increased after the cessation of AZM administration. The ratio increased significantly in inflamed tissue (9.5-26.2).

Evidence-based medicine: the design and interpretation of noninferiority clinical trials in veterinary medicine

Noninferiority trials are clinical studies designed to demonstrate that an investigational drug is at least as effective as an established treatment within a predetermined margin. They are conducted, in part, because of ethical concerns of administering a placebo to veterinary patients when an established effective treatment exists. The use of noninferiority trial designs has become more common in veterinary medicine with the increasing number of established veterinary therapeutics and the desire to eliminate potential pain or distress in a placebo-controlled study. Selecting the appropriate active control and an a priori noninferiority margin between the investigational and active control drug are unique and critical design factors for noninferiority studies. Without reliable historical knowledge of the disease response in the absence of treatment and of the response to the selected active control drug, proper design and interpretation of a noninferiority trial is not possible. Despite the appeal of conducting noninferiority trials to eliminate ethical concerns of placebo-controlled studies, there are real limitations and possible ethical conundrums associated with noninferiority trials. The consequences of incorrect study conclusions because of poor noninferiority trial design need careful attention. Alternative trial designs to typical noninferiority studies exist, but these too have limitations and must also be carefully considered.

Suggested guidelines for using systemic antimicrobials in bacterial skin infections: part 2-- antimicrobial choice, treatment regimens and compliance

Systemic antimicrobials are critically important in veterinary healthcare, and resistance is a major concern. Antimicrobial stewardship will be important in maintaining clinical efficacy by reducing the development and spread of antimicrobial resistance. Bacterial skin infections are one of the most common reasons for using systemic antimicrobials in dogs and cats. Appropriate management of these infections is, therefore, crucial in any policy for responsible antimicrobial use. The goals of therapy are to confirm that an infection is present, identify the causative bacteria, select the most appropriate antimicrobial, ensure that the infection is treated correctly, and to identify and manage any underlying conditions. This is the second of two articles that provide evidence-led guidelines to help practitioners address these issues. Part 1 discussed the use of clinical signs, cytology and culture in diagnosis. This article will cover the rationale for topical and systemic antimicrobial therapy, including choice of first-, second- and third-line drugs, the dose, duration of therapy, compliance and identification of underlying predisposing conditions. In addition, there is guidance on cases of therapeutic failure and environmental hygiene. These guidelines will help veterinarians avoid the development and propagation of antimicrobial-resistant bacterial strains.

Usefulness of cefovecin disk-diffusion test for predicting mecA gene-containing strains of Staphylococcus pseudintermedius and clinical efficacy of cefovecin in dogs with superficial pyoderma

BACKGROUND

Cefovecin has been widely used to treat skin infections in dogs. The relationship of the cefovecin disk-diffusion test results to the presence of the mecA gene and the clinical efficacy of cefovecin have not been fully evaluated.

HYPOTHESIS/OBJECTIVES

To determine the usefulness of an in vitro cefovecin disk-diffusion test in predicting the presence of the mecA gene in Staphylococcus pseudintermedius, as well as the in vivo efficacy of cefovecin therapy in dogs with superficial pyoderma.

METHODS

Twenty-six S. pseudintermedius strains isolated from 22 dogs with pyoderma were used. In vitro disk-diffusion test results of cefovecin were compared with agar-dilution test results, the presence of the mecA gene, and the improvement in clinical scores of dogs with superficial pyoderma at 14 days post treatment.

RESULTS

There was a significant linear correlation (r = -0.83) between the diameter of the obvious zone of inhibition by disk diffusion and the minimal inhibitory concentration for cefovecin (P < 0.0001). Receiver operating characteristic analysis revealed that zone diameters between 25 and 27 mm exhibited better sensitivity (92.9%) and specificity (100.0%) for detection of strains carrying the mecA gene. The mean improvement in clinical scores in dogs carrying cefovecin-resistant strains was significantly lower than in dogs carrying cefovecin-susceptible strains (P < 0.01).

CONCLUSIONS AND CLINICAL IMPORTANCE

The cefovecin disk-diffusion test with a cut-off value estimated in this study was valuable for predicting mecA gene carriage in S. pseudintermedius, as well as the in vivo efficacy of cefovecin therapy in dogs with superficial pyoderma caused by S. pseudintermedius.

The effectiveness of systemic antimicrobial treatment in canine superficial and deep pyoderma: a systematic review

AIM

To identify and evaluate existing evidence for the effectiveness of systemic antimicrobial treatments for naturally occurring superficial and deep canine pyoderma.

METHOD

Electronic searches of PubMed, MEDLINE and CAB Direct were carried out (25 May 2011) without date or language restrictions. Proceedings of ESVD/ECVD, AAVD/ACVD, NAVDF and WCVD annual congresses were searched. Unpublished studies were sought via the Veterinary Dermatology discussion list and Veterinary Information Network.

RESULTS

Seventeen full-length, peer-reviewed controlled trials reporting clinical outcomes of systemic antimicrobial treatment for canine pyoderma were identified. Outcomes specific to superficial or deep pyoderma were reported in nine and five studies, respectively. Five studies reported outcomes only for nondifferentiated pyoderma depth. Heterogeneity of study designs and outcome measures made meta-analysis inappropriate. A good level of evidence was identified supporting the high efficacy of subcutaneously injected cefovecin in superficial pyoderma and for oral amoxicillin-clavulanic acid in deep pyoderma. A fair level of evidence was identified for moderate to high efficacy of oral amoxicillin-clavulanic acid, clindamycin, cefadroxil, trimethoprim-sulphamethoxazole and sulfadimethoxine-ormetoprim in superficial pyoderma and oral pradofloxacin, oral cefadroxil and subcutaneously injected cefovecin in deep pyoderma. Eleven trials reported observations of adverse effects in treated pyoderma cases by intervention group; four dogs were withdrawn owing to the severity of adverse effects.

CONCLUSIONS

There is a need for greater numbers of adequately sized, blinded, randomized controlled trials evaluating systemic antimicrobial interventions for canine pyoderma. Improved differentiation between superficial and deep pyoderma in outcome reporting, outcome measure standardization and association of outcomes with causative bacterial species and their resistance patterns are required.

Effectiveness and safety of cefovecin sodium, an extended-spectrum injectable cephalosporin, in the treatment of cats with abscesses and infected wounds

OBJECTIVE

To evaluate the effectiveness and safety of cefovecin sodium in the treatment of cats with naturally occurring skin infections (abscesses and infected wounds).

DESIGN

Multicenter (26 sites), randomized, double-blind, controlled clinical trial.

ANIMALS

Client-owned cats of any breed with naturally occurring skin infections with associated clinical signs and confirmatory bacteriologic culture results.

PROCEDURES

Cats with clinical signs of skin and soft tissue infection were randomly allocated to receive a single dose of cefovecin (8 mg/kg [3.6 mg/lb], SC) followed by placebo drops administered orally once daily for 14 days or 1 SC placebo injection followed by cefadroxil (22 mg/kg [10 mg/lb], PO, once daily for 14 days). Only one 14-day treatment course was permitted.

RESULTS

Effectiveness of cefovecin in the treatment of cats with abscesses and infected wounds was similar to that of cefadroxil. At the final assessment on day 28, 97% (86/89) of cefovecin-treated cats and 91% (80/88) of cefadroxil-treated cats were considered treatment successes. There were no serious adverse events or deaths related to treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

1 SC injection of 8 mg of cefovecin/kg for the treatment of cats with naturally occurring skin infections (wounds and abscesses) was safe and as effective as cefadroxil administered orally at 22 mg/kg, once daily for 14 days.

Efficacy and safety of cefovecin in treating bacterial folliculitis, abscesses, or infected wounds in dogs

OBJECTIVE

To evaluate the efficacy and safety of administration of cefovecin, compared with cefadroxil, for treatment of naturally occurring secondary superficial pyoderma, abscesses, and infected wounds in dogs.

DESIGN

Multicenter, randomized, positive-controlled clinical trial.

ANIMALS

235 client-owned dogs.

PROCEDURES

Dogs with clinical signs of skin infection confirmed via bacteriologic culture were randomly allocated to receive a single SC injection of cefovecin (8 mg/kg [3.6 mg/lb]) followed by placebo administered PO twice daily for 14 days or cefadroxil (22 mg/kg [10 mg/lb]) administered PO twice daily for 14 days following a placebo injection. Two 14-day treatment courses were permitted. Treatment success was defined as reduction of clinical signs to mild or absent at the final assessment.

RESULTS

Clinical efficacy achieved with cefovecin in dogs was equivalent to that observed with cefadroxil. At the final assessment, 14 days following the completion of treatment (on day 28 or 42), 92.4% (109/118) of the cefovecin group and 92.3% (108/117) of the cefadroxil group were treatment successes. There were no serious adverse events or deaths related to treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

A single cefovecin injection (8 mg/kg) administered SC, which could be repeated once after 14 days, was safe and effective against naturally occurring skin infections in dogs and as effective as cefadroxil administered PO twice daily for 14 or 28 days.