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.
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
E A
EA
Eady
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Coates
J I
JI
Ross
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Ratyal
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Cove
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