A study for the isolation of the causative organism,antimicrobial susceptibility tests and therapeutic aspects in patients with impetigo

Park, Sung Wook; Wang, Han Young; Sung, Ho Suk

Abstract

BACKGROUND: It is traditiqnally considered that the non-bullous fonn of impetigo is primarily of streptococcal origin and the bullous form is of staphylococcal origin. However, recent reports have shown that Staphylococcus aureus (SA) has become the predominant cauative pathogen of non-bullous impetigo as well as of bullous impetigo. Objective. Our purpose was to evaluate the predominant causativi. pathogen, and to establish a therapeutic guideline for impetigo. METHOD: We described the characteristics of lesions and gerformed bacterial culture and susceptibility tests in patients with impetigo. Patients were treatecl by one of three frequently used antibiotics(erythromycin, cefuroxime, fusidic acid).
RESULTS
Of 77 patients, there were 47 cases of crusted type(61.9%), 18 cases of mixed type with crusted and bullous lesiona(23.3%), 7 cases of mixed type with crusted and pustular lesions(9.1%) and 5 cases of bullous type(6.6%). SA was grown from 90.1% af the cases, in 83.1% of cases it was the only organism to be foind and no gowth of streptococcus was faund even in mixed infections. An antimicrobial susceptibility test of 63 strains of SA demonstrated high susceptibility to vancomycin(98.4%), cefuroxime(97.1%), oxacillin(96.4%), cephalothin(95.2%), fusidic acid(91.7%) etc, and high resistance to penicillin(93.7%), gentamicin(90.5%), tobramycin(88.9%) and erythromicin(80.9%). Of 19 patients treated with erythrornycin, 12(63.1% ) showed treatment failure at a weeks, while no treatment failure occured in groups treated with cefuroxime and usidic acid. There were statistically significant differences iri therapeutic effect between cefuroxirne and erythromycin(P=0.005 by two tailedy test), and betweer fusidic acid and erythromycin(P=0.0040. But there was no significant difference between cefuroxime and fusidic acid.
CONCLUSION
The predominant pathogen of non-bullous impetigo a well as bullous impetigo was SA which were highly resistant to erythromycin and highly sensitive to efuroxime and fusidic acid. In the clinical response, cefuroxinie and fusidic acid treatment were most effective and erythromycin was inadequate for treatment of impetigo.