In vitro evaluation of the use of diluted sodium hypochlorite (bleach) against Staphylococcus pseudintermedius ,Pseudomonas aeruginosa and Malassezia pachydermatis

Evaluation of hypochlorous acid as an ear flush in dogs with chronic otitis externa

BACKGROUND

Chronic otitis externa (OE) in dogs frequently requires anaesthetised ear flushing.

OBJECTIVES

To evaluate hypochlorous acid as an ear flushing and antimicrobial agent in dogs with chronic OE.

ANIMALS

Twenty dogs with chronic OE caused by the same organisms bilaterally.

MATERIALS AND METHODS

One ear was flushed under anaesthesia with hypochlorous acid, the other with saline solution. Subsequently, the ear flushed with hypochlorous acid was cleaned with the same solution twice daily for 2 weeks, the other ear with a commercial ear cleaner. An ear medication containing miconazole, polymyxin B and prednisolone was used once daily in both ears. Clinical scores were determined before the flush. Ear cytological results were obtained, a hearing test was conducted before and after the ear flush, and a culture was taken directly after flushing. Ears were evaluated after 2 weeks of therapy.

RESULTS

Yeast was present in the ears of 11, cocci in one and a mixed infection in eight dogs. Five ears were negative on culture after flushing with hypochlorous acid, one after the saline flush. Clinical and cytological scores decreased significantly with both solutions after 2 weeks of treatment. There was no difference between treatments in any of the scores at any time point between treatments and in the results of the hearing test before and after the flushing procedure. Adverse effects were not seen.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypochlorous acid is a suitable cleaning solution for canine OE.

Efficacy of sodium hypochlorite against multidrug-resistant Gram-negative bacteria

BACKGROUND

Increased antimicrobial resistance has been observed among many bacteria leading to treatment failures in human and veterinary medicine. Disinfection is a prerequisite for infection control and prevention in healthcare settings. Chlorine compounds are cost-effective and accessible worldwide.

AIM

To determine the efficacy of sodium hypochlorite (NaOCl) against multidrug-resistant Gram-negative bacteria (MDR-GNB).

METHODS

Minimum inhibitory concentrations (MICs) were determined using broth macro-dilution. Bactericidal efficacy was measured by qualitative and quantitative suspension tests followed by practical tests without mechanical action on stainless steel carriers. The guidelines of the German Association for Applied Hygiene were followed.

FINDINGS

Results varied remarkably depending on the method. MICs were 0.1% or 0.2% NaOCl. Qualitative suspension tests revealed up to 500-fold lower bactericidal concentrations. Pseudomonas aeruginosa (P = 0.0025) was significantly less susceptible in these tests whereas quantitative suspension tests revealed no significant differences between strains (P > 0.05). Practical tests determined bactericidal concentrations of 0.8-0.32% NaOCl at 1 min of contact and even lower concentrations for longer contact times. At 1 min, five Klebsiella were significantly less susceptible (P = 0.0124), whereas the lower susceptibility of P. aeruginosa was not confirmed. Organic load inhibited bactericidal activity significantly, whereas contact time had a marginal effect. Differing test results underline that MIC determination and qualitative suspension tests may be insufficient approaches to evaluate bacterial susceptibility or resistance.

CONCLUSION

NaOCl efficiently reduced Pseudomonas aeruginosa, Acinetobacter spp., and Klebsiella spp., most notably in the absence of organic matter. Strain- and species-specific differences in susceptibility were noticed, but in general MDR-GNB revealed no higher tolerance to NaOCl.

Recommendations for approaches to meticillin-resistant staphylococcal infections of small animals: diagnosis, therapeutic considerations and preventative measures.: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Multiple drug resistance (MDR) in staphylococci, including resistance to the semi-synthetic penicillinase-resistant penicillins such as meticillin, is a problem of global proportions that presents serious challenges to the successful treatment of staphylococcal infections of companion animals.

OBJECTIVES

The objective of this document is to provide harmonized recommendations for the diagnosis, prevention and treatment of meticillin-resistant staphylococcal infections in dogs and cats.

METHODS

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to September 2016. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) provided guidance and oversight for this process. A draft of the document was presented at the 8th World Congress of Veterinary Dermatology (May 2016) and was then made available via the World Wide Web to the member organizations of the WAVD for a period of three months. Comments were solicited and posted to the GP electronically. Responses were incorporated by the GP into the final document.

CONCLUSIONS

Adherence to guidelines for the diagnosis, laboratory reporting, judicious therapy (including restriction of use policies for certain antimicrobial drugs), personal hygiene, and environmental cleaning and disinfection may help to mitigate the progressive development and dissemination of MDR staphylococci.

Diluted sodium hypochlorite (bleach) in dogs: antiseptic efficacy, local tolerability and in vitro effect on skin barrier function and inflammation

BACKGROUND

Diluted sodium hypochlorite represents an inexpensive and widely available topical antiseptic, but there are no tolerability and efficacy data in veterinary dermatology.

OBJECTIVES

To determine the in vivo antibacterial effect and tolerability of topical diluted bleach application and to assess its in vitro effect on skin barrier lipids and anti-inflammatory properties on keratinocytes.

METHODS

Topical hypochlorite at 0.05% and tap water were applied to both sides of the thorax of four healthy dogs. The anti-inflammatory effect on canine keratinocytes was determined by real-time polymerase chain reaction; skin barrier integrity was assessed by evaluating stratum corneum lipid changes in canine stratified epidermal constructs.

RESULTS

The cell viability of primary keratinocytes treated with water and diluted hypochlorite at 0.005 and 0.01%, reduced the percentage of viable cells by 10%. The exposure of primary keratinocytes to 0.005% diluted hypochlorite significantly reduced the induction of inflammatory genes chemokine ligand-2 (CCL2; P = 0.015) and thymus and activation-regulated chemokine (TARC/CCL17, P = 0.032). There were no changes in skin lipid ceramide and nonceramide fractions in stratified epidermal constructs cultured for 17 days with 0.05% hypochlorite. Topical hypochlorite at 0.05% and tap water were well-tolerated without signs of skin irritation. Although a marked reduction in bacterial counts was seen within 20 min of diluted bleach application compared to the tap water control, this was only marginally significant (P = 0.06).

CONCLUSIONS AND CLINICAL IMPORTANCE

The results indicate that a topical diluted bleach solution, at either 0.05 or 0.005% hypochlorite concentrations, is a well-tolerated antiseptic that also exhibits anti-inflammatory properties.