Topical antimicrobial agents for preventing and treating foot infections in people with diabetes

Topical antimicrobial agents for treating foot ulcers in people with diabetes

BACKGROUND

People with diabetes are at high risk for developing foot ulcers, which often become infected. These wounds, especially when infected, cause substantial morbidity. Wound treatments should aim to alleviate symptoms, promote healing, and avoid adverse outcomes, especially lower extremity amputation. Topical antimicrobial therapy has been used on diabetic foot ulcers, either as a treatment for clinically infected wounds, or to prevent infection in clinically uninfected wounds.

OBJECTIVES

To evaluate the effects of treatment with topical antimicrobial agents on: the resolution of signs and symptoms of infection; the healing of infected diabetic foot ulcers; and preventing infection and improving healing in clinically uninfected diabetic foot ulcers.

SEARCH METHODS

We searched the Cochrane Wounds Specialised Register, CENTRAL, Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations), Ovid Embase, and EBSCO CINAHL Plus in August 2016. We also searched clinical trials registries for ongoing and unpublished studies, and checked reference lists to identify additional studies. We used no restrictions with respect to language, date of publication, or study setting.

SELECTION CRITERIA

We included randomised controlled trials conducted in any setting (inpatient or outpatient) that evaluated topical treatment with any type of solid or liquid (e.g., cream, gel, ointment) antimicrobial agent, including antiseptics, antibiotics, and antimicrobial dressings, in people with diabetes mellitus who were diagnosed with an ulcer or open wound of the foot, whether clinically infected or uninfected.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, 'Risk of bias' assessment, and data extraction. Initial disagreements were resolved by discussion, or by including a third review author when necessary.

MAIN RESULTS

We found 22 trials that met our inclusion criteria with a total of over 2310 participants (one study did not report number of participants). The included studies mostly had small numbers of participants (from 4 to 317) and relatively short follow-up periods (4 to 24 weeks). At baseline, six trials included only people with ulcers that were clinically infected; one trial included people with both infected and uninfected ulcers; two trials included people with non-infected ulcers; and the remaining 13 studies did not report infection status.Included studies employed various topical antimicrobial treatments, including antimicrobial dressings (e.g. silver, iodides), super-oxidised aqueous solutions, zinc hyaluronate, silver sulphadiazine, tretinoin, pexiganan cream, and chloramine. We performed the following five comparisons based on the included studies: Antimicrobial dressings compared with non-antimicrobial dressings: Pooled data from five trials with a total of 945 participants suggest (based on the average treatment effect from a random-effects model) that more wounds may heal when treated with an antimicrobial dressing than with a non-antimicrobial dressing: risk ratio (RR) 1.28, 95% confidence interval (CI) 1.12 to 1.45. These results correspond to an additional 119 healing events in the antimicrobial-dressing arm per 1000 participants (95% CI 51 to 191 more). We consider this low-certainty evidence (downgraded twice due to risk of bias). The evidence on adverse events or other outcomes was uncertain (very low-certainty evidence, frequently downgraded due to risk of bias and imprecision). Antimicrobial topical treatments (non dressings) compared with non-antimicrobial topical treatments (non dressings): There were four trials with a total of 132 participants in this comparison that contributed variously to the estimates of outcome data. Evidence was generally of low or very low certainty, and the 95% CIs spanned benefit and harm: proportion of wounds healed RR 2.82 (95% CI 0.56 to 14.23; 112 participants; 3 trials; very low-certainty evidence); achieving resolution of infection RR 1.16 (95% CI 0.54 to 2.51; 40 participants; 1 trial; low-certainty evidence); undergoing surgical resection RR 1.67 (95% CI 0.47 to 5.90; 40 participants; 1 trial; low-certainty evidence); and sustaining an adverse event (no events in either arm; 81 participants; 2 trials; very low-certainty evidence). Comparison of different topical antimicrobial treatments: We included eight studies with a total of 250 participants, but all of the comparisons were different and no data could be appropriately pooled. Reported outcome data were limited and we are uncertain about the relative effects of antimicrobial topical agents for each of our review outcomes for this comparison, that is wound healing, resolution of infection, surgical resection, and adverse events (all very low-certainty evidence). Topical antimicrobials compared with systemic antibiotics : We included four studies with a total of 937 participants. These studies reported no wound-healing data, and the evidence was uncertain for the relative effects on resolution of infection in infected ulcers and surgical resection (very low certainty). On average, there is probably little difference in the risk of adverse events between the compared topical antimicrobial and systemic antibiotics treatments: RR 0.91 (95% CI 0.78 to 1.06; moderate-certainty evidence - downgraded once for inconsistency). Topical antimicrobial agents compared with growth factor: We included one study with 40 participants. The only review-relevant outcome reported was number of ulcers healed, and these data were uncertain (very low-certainty evidence).

AUTHORS' CONCLUSIONS

The randomised controlled trial data on the effectiveness and safety of topical antimicrobial treatments for diabetic foot ulcers is limited by the availability of relatively few, mostly small, and often poorly designed trials. Based on our systematic review and analysis of the literature, we suggest that: 1) use of an antimicrobial dressing instead of a non-antimicrobial dressing may increase the number of diabetic foot ulcers healed over a medium-term follow-up period (low-certainty evidence); and 2) there is probably little difference in the risk of adverse events related to treatment between systemic antibiotics and topical antimicrobial treatments based on the available studies (moderate-certainty evidence). For each of the other outcomes we examined there were either no reported data or the available data left us uncertain as to whether or not there were any differences between the compared treatments. Given the high, and increasing, frequency of diabetic foot wounds, we encourage investigators to undertake properly designed randomised controlled trials in this area to evaluate the effects of topical antimicrobial treatments for both the prevention and the treatment of infection in these wounds and ultimately the effects on wound healing.

Systemic antibiotics for treating diabetic foot infections

BACKGROUND

Foot infection is the most common cause of non-traumatic amputation in people with diabetes. Most diabetic foot infections (DFIs) require systemic antibiotic therapy and the initial choice is usually empirical. Although there are many antibiotics available, uncertainty exists about which is the best for treating DFIs.

OBJECTIVES

To determine the effects and safety of systemic antibiotics in the treatment of DFIs compared with other systemic antibiotics, topical foot care or placebo.

SEARCH METHODS

In April 2015 we searched the Cochrane Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library); Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE, and EBSCO CINAHL. We also searched in the Database of Abstracts of Reviews of Effects (DARE; The Cochrane Library), the Health Technology Assessment database (HTA; The Cochrane Library), the National Health Service Economic Evaluation Database (NHS-EED; The Cochrane Library), unpublished literature in OpenSIGLE and ProQuest Dissertations and on-going trials registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating the effects of systemic antibiotics (oral or parenteral) in people with a DFI. Primary outcomes were clinical resolution of the infection, time to its resolution, complications and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed the risk of bias, and extracted data. Risk ratios (RR) were estimated for dichotomous data and, when sufficient numbers of comparable trials were available, trials were pooled in a meta-analysis.

MAIN RESULTS

We included 20 trials with 3791 participants. Studies were heterogenous in study design, population, antibiotic regimens, and outcomes. We grouped the sixteen different antibiotic agents studied into six categories: 1) anti-pseudomonal penicillins (three trials); 2) broad-spectrum penicillins (one trial); 3) cephalosporins (two trials); 4) carbapenems (four trials); 5) fluoroquinolones (six trials); 6) other antibiotics (four trials).Only 9 of the 20 trials protected against detection bias with blinded outcome assessment. Only one-third of the trials provided enough information to enable a judgement about whether the randomisation sequence was adequately concealed. Eighteen out of 20 trials received funding from pharmaceutical industry-sponsors.The included studies reported the following findings for clinical resolution of infection: there is evidence from one large trial at low risk of bias that patients receiving ertapenem with or without vancomycin are more likely to have resolution of their foot infection than those receiving tigecycline (RR 0.92, 95% confidence interval (CI) 0.85 to 0.99; 955 participants). It is unclear if there is a difference in rates of clinical resolution of infection between: 1) two alternative anti-pseudomonal penicillins (one trial); 2) an anti-pseudomonal penicillin and a broad-spectrum penicillin (one trial) or a carbapenem (one trial); 3) a broad-spectrum penicillin and a second-generation cephalosporin (one trial); 4) cephalosporins and other beta-lactam antibiotics (two trials); 5) carbapenems and anti-pseudomonal penicillins or broad-spectrum penicillins (four trials); 6) fluoroquinolones and anti-pseudomonal penicillins (four trials) or broad-spectrum penicillins (two trials); 7) daptomycin and vancomycin (one trial); 8) linezolid and a combination of aminopenicillins and beta-lactamase inhibitors (one trial); and 9) clindamycin and cephalexin (one trial).Carbapenems combined with anti-pseudomonal agents produced fewer adverse effects than anti-pseudomonal penicillins (RR 0.27, 95% CI 0.09 to 0.84; 1 trial). An additional trial did not find significant differences in the rate of adverse events between a carbapenem alone and an anti-pseudomonal penicillin, but the rate of diarrhoea was lower for participants treated with a carbapenem (RR 0.58, 95% CI 0.36 to 0.93; 1 trial). Daptomycin produced fewer adverse effects than vancomycin or other semi-synthetic penicillins (RR 0.61, 95%CI 0.39 to 0.94; 1 trial). Linezolid produced more adverse effects than ampicillin-sulbactam (RR 2.66; 95% CI 1.49 to 4.73; 1 trial), as did tigecycline compared to ertapenem with or without vancomycin (RR 1.47, 95% CI 1.34 to 1.60; 1 trial). There was no evidence of a difference in safety for the other comparisons.

AUTHORS' CONCLUSIONS

The evidence for the relative effects of different systemic antibiotics for the treatment of foot infections in diabetes is very heterogeneous and generally at unclear or high risk of bias. Consequently it is not clear if any one systemic antibiotic treatment is better than others in resolving infection or in terms of safety. One non-inferiority trial suggested that ertapenem with or without vancomycin is more effective in achieving clinical resolution of infection than tigecycline. Otherwise the relative effects of different antibiotics are unclear. The quality of the evidence is low due to limitations in the design of the included trials and important differences between them in terms of the diversity of antibiotics assessed, duration of treatments, and time points at which outcomes were assessed. Any further studies in this area should have a blinded assessment of outcomes, use standardised criteria to classify severity of infection, define clear outcome measures, and establish the duration of treatment.