November/December 2015
CORRESPONDENCE
Table. Antibiotic Sensitivity Results of the Index Case Antimicrobial Agent
Minimum Inhibitory Concentration/Interpretive Criteria, µg/mL3
Results
Sensitive
Intermediate
Resistant
Ampicillin
≤8
16
≥32
Intermediate resistant
Doxycycline
≤4
8
≥16
Resistant
Ciprofloxacin
≤1
2
≥4
Sensitive
Levofloxacin
≤0.12
0.25–1
≥2
Sensitive
Trimethoprim-sulfamethoxazole
≤2/38
–
≥4/76
Resistant
Of all the enterobacteriacae, E coli, Klebsiella species, and Proteus species cause the majority of the cases of GNF.10 While trimethoprim, cotrimoxazole, and ampicillin have been used in the treatment of GNF,10 the present MIC values2 (Table) do not favor their use. All strains of Klebsiella express a chromosomally encoded β-lactamase that confers resistance to ampicillin, while Proteus vulgaris, Enterobacter, and Serratia frequently harbor plasmids.11 For these organisms, quinolones are an ideal drug class.11 Levofloxacin is two-fold more potent than other quinolones, is as active as ciprofloxacin, and its convenient dosages (once a day) make it the ideal quinolone for enterobacteriaceae infections.11 Conclusions Many patients have ordinary acne vulgaris in addition to GNF. Once the folliculitis has responded, the residual acne should be treated by other means.10 In GNF, an initial targeted antimicrobial for a short duration makes microbiologic sense,10 compared with giving only isotretinoin, which has no in vitro activity against gram-negative organisms.8 Our case demonstrates that levofloxacin with its convenient dosages can be a useful therapy for GNF. The rapid response with levofloxacin (Figure 2) suggests its use as a “bridge therapy” in GNF for unresponsive cases.9 References 1 Eady EA, Cove JH, Blake J, et al. Recalcitrant acne vulgaris. Clinical, biochemical and microbiological investigation of patients not responding to antibiotic treatment. Br J Dermatol. 1988;118:415–423.
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2 Sardana K, Gupta T, Garg VK, et al. Antibiotic resistance to Propionibacterium acnes: worldwide scenario, diagnosis and management. Expert Rev Anti Infect Ther. 2015;13:883–896. 3 Patel JB, Cockerill III FR, Alder J, et al. Performance Standards for Antimicrobial Susceptibility Testing; Twenty-Fourth Informational Supplement (M100-S24). Clinical and Laboratory Standards Institute antimicrobial susceptibility testing. 2014;34:1–230. 4 James WD, Leyden JJ. Treatment of gram-negative folliculitis with isotretinoin: positive clinical and microbiologic response. J Am Acad Dermatol. 1985;12:319–324. 5 Böni, Nehrhoff B. Treatment of gram-negative folliculitis in patients with acne. Am J Clin Dermatol. 2003;4:273– 276. 6 Simjee S, Sahm DF, Soltani K, Morello JA. Organisms associated with gram-negative folliculitis: in vitro growth in the presence of isotretinoin. Arch Dermatol Res. 1986;278:314–316. 7 Hughes BR, Cunliffe WJ. A prospective study of the effect of isotretinoin on the follicular reservoir and sustainable sebum excretion rate in patients with acne. Arch Dermatol. 1994;130:315–318. 8 Neubert U, Plewig G, Ruhfus A. Treatment of gramnegative folliculitis with isotretinoin. Arch Dermatol Res. 1986;278:307–313. 9 Poli F, Prost C, Revuz J. Gram-negative bacteria folliculitis. Ann Dermatol Venereol. 1988;115:797–800. 10 Leyden JJ, Marples RR, Mills Jr OH, et al. Gram-negative folliculitis––a complication of antibiotic therapy in acne vulgaris. Br J Dermatol. 1973;88:533–538. 11 Hauser AL, Enterobacteriaceae. In: Hauser AL, ed. The ABCs of Choosing the Right Antibacterial Agent. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:121– 139.
Efficacy of a Single Daily Dose of Levofloxacin