Allergic contact dermatitis from colistin

Colistin and polymyxin B in critical care

The emergence of gram-negative bacteria resistant to most available antibiotics has led to the readministration of polymyxins B and E (colistin) as "salvage" therapy in critically ill patients. Recent studies demonstrated acceptable effectiveness and considerably less toxicity than reported in older studies of polymyxins. These old antibiotics may be administered for the treatment of intensive care unit-acquired infections of various types, including ventilator-associated pneumonia, urinary tract infections, bacteremia, and meningitis caused by multidrug resistant gram-negative pathogens, such as Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, and Enterobacter species. Randomized controlled trials are urgently needed to further clarify various issues regarding the effectiveness and safety of polymyxins, however.

Toxicity of polymyxins: a systematic review of the evidence from old and recent studies

Background

The increasing problem of multidrug-resistant Gram-negative bacteria causing severe infections and the shortage of new antibiotics to combat them has led to the re-evaluation of polymyxins. These antibiotics were discovered from different species of Bacillus polymyxa in 1947; only two of them, polymyxin B and E (colistin), have been used in clinical practice. Their effectiveness in the treatment of infections due to susceptible Gram-negative bacteria, including Pseudomonas aeruginosa and Acinetobacter baumannii, has not been generally questioned. However, their use was abandoned, except in patients with cystic fibrosis, because of concerns related to toxicity.

Methods

We reviewed old and recent evidence regarding polymyxin-induced toxicity by searching Pubmed (from 1950 until May 2005).

Results

It was reported in the old literature that the use of polymyxins was associated with considerable toxicity, mainly nephrotoxicity and neurotoxicity, including neuromuscular blockade. However, recent studies showed that the incidence of nephrotoxicity is less common and severe compared to the old studies. In addition, neurotoxic effects of polymyxins are usually mild and resolve after prompt discontinuation of the antibiotics. Furthermore, cases of neuromuscular blockade and apnea have not been reported in the recent literature.

Conclusion

New evidence shows that polymyxins have less toxicity than previously reported. The avoidance of concurrent administration of nephrotoxic and/or neurotoxic drugs, careful dosing, as well as more meticulous management of fluid and electrolyte abnormalities and use of critical care services may be some of the reasons for the discrepancy between data reported in the old and recent literature.

Contact dermatitis due to sodium colistimethate

Colistin methanesulfonate sodium (CLMS) is a widely-used antibiotic. To our best knowledge, only two cases of contact allergy to CLMS have been reported. We described a 4-year-old girl with contact dermatitis evoked by CLMS that had been applied as an ophthalmic solution. The dermatitis started after administration for 21 days. The diagnosis was confirmed by as is and constituent patch tests. We reviewed the literature in which contact allergy due to CLMS and colistin sulfate is described.