Effects of pH on the Antibiotic Resistance of Bacteria Recovered from Diabetic Foot Ulcer Fluid An In Vitro Study.

BACKGROUND: This study investigated the resistance of bacteria isolated from diabetic foot ulcers (DFUs) to antibiotics frequently used in the management of the diabetic foot infections, at a range of pH values (pH 6.5, 7.5, and 8.5) known to exist in DFU wound fluid. This study aimed to determine whether changes (or atypical stasis) in wound fluid pH modulate the antibiotic resistance of DFU isolates, with potential implications in relation to the suppression/eradication of bacterial infections in DFUs. METHODS: Thirty bacterial isolates were recovered from DFU wound fluid, including Staphylococcus spp, Staphylococcus aureus, Escherichia coli, Streptococcus spp, Pseudomonas spp, and Pseudomonas aeruginosa. The resistances of these isolates to a panel of antibiotics currently used in the treatment of infected or potentially infected DFUs, ie, ciprofloxacin, amoxicillin-clavulanate, doxycycline, and piperacillin-tazobactam, at the previously mentioned pH values were determined by a modification of the Kirby-Bauer assay. RESULTS: The resistance of DFU isolates to clinically relevant antibiotics was significantly affected by the pH levels in DFU wound fluid. CONCLUSIONS: These findings highlight the importance of a more comprehensive understanding of the conditions in DFUs to inform clinical decision making in the selection and application of antibiotics in treating these difficult-to-heal wounds. The scale of the differences in the efficacies of antibiotics at the different pH values examined is likely to be sufficient to suggest reconsideration of the antibiotics of choice in the treatment of DFU infection.

The pH of wound fluid in diabetic foot ulcers -- the way forward in detecting clinical infection?

Infections within diabetic foot ulcers are often hard to detect and extremely difficult to treat. The normal signs and symptoms of infection including purulence, erythema, pain, tenderness, warmth and induration are frequently absent in such wounds necessitating exploration of other ways of rapidly and accurately detecting infection. This study considers diabetic wound fluid pH as a possible alternative means of monitoring infection status. CINAHL, Ovid SP and MEDLINE were searched for papers in English published between January 2004 to May 2014. Key search terms included wound fluid, exudate, wound, ulcer, diabetes, pH, healing, infection, bacteria. This paper considers the potential benefits of augmenting and supporting current clinical practice in the early determination of wound healing trajectory and infection status, by monitoring wound fluid pH. The evidence collected highlights the need for further research and suggests the potential of wound fluid analysis as a possible surrogate marker for detecting infection in diabetic foot ulcers.

Low-intensity laser therapy/combined phototherapy in the management of chronic venous ulceration: a placebo-controlled study.

OBJECTIVE: The current placebo-controlled study was undertaken to investigate the efficacy of combined phototherapy and low-intensity laser therapy (LILT) in the management of chronic venous ulceration when used in conjunction with standardized nursing intervention. MATERIALS AND METHODS: Approval was granted by Research Ethical Committees at the University of Ulster and Altnagelvin Hospitals Health and Social Services Trust. Patients (n = 15; 10 female/5 male; age +/- SD = 69.9 +/- 13.8 years) were recruited from an outpatient "leg ulcer clinic," where they attended once per week for irradiation/sham treatments for 4 weeks. Treatment was withheld for a total of 8 weeks, and patients were reviewed during this time (weeks 8 and 12) for ulcer and pain assessment only. A multisource diode array (660-950 nm) was used for irradiation; parameters were kept constant for the duration of the study (532 mW; 5 kHz; 12 J/cm(2)). Wound and pain assessment were carried out by an independent investigator. Digitizing was used to quantify surface areas from wound tracings. RESULTS: Although there was no statistically significant difference between Treatment and Placebo groups, an apparent clinical difference in wound healing rate was noted; at postirradiation, a continued reduction in wound size was evident for the treatment group. These effects were believed to be due to an apparent delayed effect. There was no statistically significant difference between groups for pain. CONCLUSION: These findings provide only limited evidence for the use of this modality as an adjunctive therapy with current nursing intervention. Further group studies are indicated to investigate the apparent delayed effect reported here for various etiologies of ulceration.