Combination of available topical beta-blockers and antibiotic ointment for epidermal growth factor receptor tyrosine kinase inhibitor-induced paronychia and pseudopyogenic granulomas in Taiwan.

BACKGROUND: Painful paronychia and pseudopyogenic granuloma (PG) are common adverse drug reactions (ADRs) associated with the use of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) to treat non-small cell lung cancer (NSCLC). Multiple local management approaches have been tested with unsatisfactory results. We have introduced an occlusion therapy technique through which available topical drugs for longer than 2 years. METHODS: Based on the cancer registry and case management system of our hospital, from July 2019 to July 2020, we retrospectively enrolled patients with NSCLC who were treated with EGFR-TKIs and received applications of 0.5% timolol ophthalmic solution (TIMOPTOL XE 0.5%®) combined with a neomycin/tyrothricin ointment (Biomycin®) using the occlusion method to treat paronychia or PG. RESULTS: A total of 22 patients were enrolled, with a mean age of 66.5 years, most of whom were women (72.7%). Periungual lesion-related pain was reported by all patients, and periungual bleeding and PG were reported in 14% (3/22) and 64% (14/22) of patients, respectively. After the occlusion therapy application of timolol ophthalmic solution combined with neomycin/tyrothricin ointment twice daily, the overall response rate was 83.3%, including complete response in 18% (4/22) of cases and partial response in 68% (15/22) of cases. CONCLUSION: We presented an occlusion method using available topical beta-blockers and antibiotic ointment for EGFR-TKI-induced paronychia and PG in Taiwan. The result is favorable. Further randomized control trial is urgent to validate our findings.

Tyrothricin--An underrated agent for the treatment of bacterial skin infections and superficial wounds?

The antimicrobial agent tyrothricin is a representative of the group of antimicrobial peptides (AMP). It is produced by Bacillus brevis and consists of tyrocidines and gramicidins. The compound mixture shows activity against bacteria, fungi and some viruses. A very interesting feature of AMPs is the fact, that even in vitro it is almost impossible to induce resistances. Therefore, this class of molecules is discussed as one group that could serve as next generation antibiotics and overcome the increasing problem of bacterial resistances. In daily practice, the application of tyrothricin containing formulations is relatively limited: It is used in sore throat medications and in agents for the healing of infected superficial and small-area wounds. However, due to the broad spectrum antimicrobial activity and the low risk of resistance development it is worth to consider further fields of application.

Decade-long use of the antimicrobial peptide combination tyrothricin does not pose a major risk of acquired resistance with gram-positive bacteria and Candida spp.

Tyrothricin, an antimicrobial peptide combination produced by Bacillus brevis consisting of gramicidins and tyrocidins commands broad antimicrobial activity against gram-positive bacteria and some yeasts in vitro. The polypeptide and its components have been used therapeutically for about 60 years in the local treatment of infected skin and infected oro-pharyngeal mucous membranes. Though older studies suggest that resistance development of originally susceptible microorganisms towards tyrothricin is a rare event, data concerning recent state of resistance are lacking. In the present in vitro study the susceptibility to tyrothricin of clinical isolates of bacterial and yeast origin from superficial swabs of the skin and mucous membranes of outpatients and inpatients obtained from clinical material in the second half of the year 2003 was determined. Using a microdilution assay, the minimum inhibitory concentration (MIC and MIC90, defined as the concentration that inhibits at least 90 percent of the tested strains) of 20 strains each of Staphylococcus aureus of the variety MSSA (susceptible to methicillin), Staphylococcus aureus of the variety MRSA (methicillin resistant), Staphylococcus haemolyticus, Streptococcus pyogenes, Enterococcus faecalis, Corynebacterium spec., Candida albicans and Candida parapsilosis was determined. All of the tested gram-positive bacteria turned out to be highly susceptible to tyrothricin with MICs ≤ 4mg/l. The tested yeast strains were susceptible to the polypeptide antibiotic as well, but (with MICs of 16 mg/l and 32 mg/l, respectively) to a lesser extent. No acquired resistance of the tested strains was determined, indicating that the risk of resistance development against topically applied tyrothricin is only marginal, if there is any at all. Thus, long-term-, i.e. decade-long use of topically applied tyrothricin and its components in the local treatment of infected skin does not pose a major risk with respect to acquired resistance of originally susceptible gram-positive bacteria and yeasts, not even in the case of Staphylococcus aureus, both with MSSA and MRSA strains. The broad anti-bacterial and anti-fungal activity of tyrothricin combined with its lacking risk for resistance development make the antimicrobial peptide a valuable addition to our therapeutic armamentarium in the treatment of infected skin.

[Tyrothricin powder in the treatment of cutaneous lesions]. / Tyrothricin-Puder bei Hautverletzungen. Reduktion des Wundradius bei infizierten und infektionsgefährdeten Wunden--Eine randomisierte, placebokontrollierte Doppelblind-Studie.

BACKGROUND AND OBJECTIVES: The efficacy and tolerance of an antiseptic wound powder based on the antibiotic tyrothricin was investigated in a prospective, randomized multicenter trial in patients with posttraumatic and surgical cutaneous lesions. PATIENTS AND METHODS: In 5 centers, 131 male and female patients from 18-85 years were included with posttraumatic or surgical cutaneous lesions with infection or in danger of infection (area > or = 200 mm2). In a double-blind study, tyrothricin (n = 62; 0.1 g tyrothricin per 100 g of vehicle) or placebo powder (n = 69) was applied to the wound twice daily for 9 days. The primary aim was to evaluate the average daily reduction of the radius from the lesion area between the start and end of the randomized treatment (alpha = 0.025; one-sided). Secondly, a wound index (range 0-15) was calculated from the assessments of rubor, crusting, exudation, pain and functional impairment. RESULTS: The treatment groups were comparable at baseline. During randomized treatment, the radius of the lesions was reduced at an average of 0.55 +/- 0.31 mm/day (mean +/- SD) for tyrothricin and 0.47 +/- 0.30 mm/day for placebo (p = 0.016; one-sided; intention-to-treat data set). The wound index decreased at an average of 4.2 +/- 1.7 and 3.3 +/- 1.9 points for tyrothricin and placebo, respectively (p = 0.0048; one-sided). 4 adverse events occurred in each group. A causal relationship with the investigational drug could not be excluded in 3 of the placebo group. CONCLUSION: The results confirm the tendency to an acceleration of wound healing by tyrothricin powder (Tyrosur Powder) in case of infection or danger of infection. A superior efficacy compared to placebo was demonstrated. Due to its good tolerability and the absence of a systemic effects tyrothricin powder is appropriate for the treatment of superficial skin lesions.