erm genes in erythromycin-resistant Staphylococcus aureus and coagulase-negative staphylococci.
Erythromycin-resistant S. aureus from general practice and a dermatology ward with a very high consumption of erythromycin was studied for ermA and ermC content by Southern blot analysis. The prevalence of these erm genes was also studied in coagulase-negative staphylococci from the same dermatology ward and in a collection of 15 S. aureus and 18 coagulase-negative staphylococci found in the same specimen from 15 different patients. ermA was only found as a chromosomal insert and ermC only on small plasmids. In erythromycin-resistant S. aureus from general practice ermC was responsible for 84% of erythromycin resistance, while 16% of the strains contained ermA. In 17 of 18 S. aureus strains from the dermatology ward a 2.5 kb plasmid contained ermC. Among 58 erythromycin-resistant coagulase-negative staphylococci only 2 (3%) had ermA, whereas 44 strains (76%) had ermC. ermA or ermC genes were common in S. epidermidis (36/38). However, in 20 isolates of erythromycin-resistant coagulase-negative staphylococci of other species, 10 had neither ermA nor ermC. ermC was the most common erm gene in both coagulase-negative staphylococci and S. aureus. In 11 of 15 patients with erythromycin-resistant S. aureus the co-isolated erythromycin-resistant coagulase-negative staphylococcus had another resistance mechanism, either another gene or a different phenotypic expression of the same gene. Resistance to pristinamycin, a streptogramin antibiotic only used in animals, was not found in S. aureus but was found in 14% of erythromycin-resistant coagulase-negative staphylococci.
Westh
H
H
Department of Clinical Microbiology, University of Copenhagen, Rigshospitalet, Denmark.
Hougaard
D M
DM
Vuust
J
J
Rosdahl
V T
VT
D000818:Animals; D001483:Base Sequence; D003030:Coagulase / Q000032:analysis* / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004917:Erythromycin / Q000494:pharmacology*; D005194:Family Practice; D005798:Genes, Bacterial; D006761:Hospitals; D006801:Humans; D008969:Molecular Sequence Data; D013210:Staphylococcus / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics
D003030:Coagulase; D004917:Erythromycin