Antibiotic resistance patterns of aerobic coryneforms and furazolidone-resistant Gram-positive cocci from the skin surface of the human axilla and fourth toe cleft.
Samples of skin surface bacteria from 28 healthy subjects plated directly on to selective and non-selective media revealed that the proportion of aerobic coryneforms and furazolidone-resistant Gram-positive cocci (FURECs) resistant to erythromycin was significantly greater in the fourth toe cleft than in the axilla (P < 0.05). There were more erythromycin-resistant bacteria than tetracycline-resistant bacteria at both sites (P = 0.001 for the toe cleft; P < 0.01 for the axilla). In total, 160 distinct isolates were obtained, of which 42 were FURECs and 118 were aerobic coryneforms. Of these, 153 (96%) were resistant to erythromycin and 66 (41%) to tetracycline. All except seven of the tetracycline-resistant strains were also resistant to erythromycin. The resistant isolates belonged to a variety of species. CDC group ANF corynebacteria were most numerous and composed 31% of all isolates. The majority (76%) of FURECs were identified as Micrococcus luteus. MIC determinations on selected strains revealed that tetracycline-resistant FURECs were sensitive to doxycycline and minocycline, as were most tetracycline-resistant coryneforms. Nine coryneform isolates were cross-resistant to all three tetracyclines. Only a minority of erythromycin-resistant FURECs (21%) demonstrated a macrolide-lincosamide-streptogramin type B (MLS)-resistant phenotype with inducible or constitutive cross-resistance to clindamycin and the type B streptogramin, pristinamycin IA. Twenty-nine erythromycin-resistant FURECs had a novel phenotype distinct from MLS and macrolide-streptogramin type B resistance. In contrast, most coryneforms (79%) were MLS resistant. Among the remainder, two unusual erythromycin resistance phenotypes were apparent, both of which differed from the unusual phenotype in FURECs. This study has revealed that the non-staphylococcal aerobic flora of skin contains a considerable reservoir of tetracycline and erythromycin resistance determinants. The three unusual macrolide resistance phenotypes may be associated with novel resistance mechanisms.
Eady
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EA
The Skin Research Centre, Division of Microbiology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. e.a.eady@leeds.ac.uk
Coates
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Ross
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Ratyal
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AH
Cove
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JH
D000192:Actinomycetales / Q000187:drug effects* / Q000378:metabolism; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001365:Axilla / Q000382:microbiology; D001420:Bacteria, Aerobic / Q000187:drug effects / Q000378:metabolism; D015169:Colony Count, Microbial; D003470:Culture Media; D004352:Drug Resistance, Microbial; D004917:Erythromycin / Q000494:pharmacology; D005260:Female; D005664:Furazolidone / Q000494:pharmacology*; D006095:Gram-Positive Cocci / Q000187:drug effects*; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D012867:Skin / Q000382:microbiology*; D013753:Tetracycline Resistance; D014034:Toes / Q000382:microbiology
D000900:Anti-Bacterial Agents; D000891:Anti-Infective Agents, Local; D003470:Culture Media; D005664:Furazolidone; D004917:Erythromycin