The mef(A) gene predominates among seven macrolide resistance genes identified in gram-negative strains representing 13 genera, isolated from healthy Portuguese children.
Of the 176 randomly selected, commensal, gram-negative bacteria isolated from healthy children with low exposure to antibiotics, 138 (78%) carried one or more of the seven macrolide resistance genes tested in this study. These isolates included 79 (91%) isolates from the oral cavity and 59 (66%) isolates from urine samples. The mef(A) gene, coding for an efflux protein, was found in 73 isolates (41%) and was the most frequently carried gene. The mef(A) gene could be transferred from the donors into a gram-positive E. faecalis recipient and a gram-negative Escherichia coli recipient. The erm(B) gene transferred and was maintained in the E. coli transconjugants but was found in 0 to 100% of the E. faecalis transconjugants tested, while the other five genes could be transferred only into the E. coli recipient. The individual macrolide resistance genes were identified in 3 to 12 new genera. Eight (10%) of the oral isolates and 30 (34%) of the urine isolates for which the MICs were 2 to >500 microg of erythromycin per ml did not hybridize with any of the seven genes and may carry novel macrolide resistance genes.
Ojo
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KK
Department of Pathobiology, Box 357238, School of Public Health and Community Medicine, University of Washington, Seattle, WA 98195, USA.
Ulep
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C
Van Kirk
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N
Luis
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H
Bernardo
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M
Leitao
J
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Roberts
M C
MC
D001426:Bacterial Proteins / Q000235:genetics*; D002648:Child; D003227:Conjugation, Genetic / Q000235:genetics; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000235:genetics; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D008565:Membrane Proteins / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D009055:Mouth / Q000382:microbiology; D011174:Portugal / Q000453:epidemiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014556:Urine / Q000382:microbiology
D001426:Bacterial Proteins; D003470:Culture Media; D004269:DNA, Bacterial; D018942:Macrolides; C117866:MefA protein, Streptococcus; D008565:Membrane Proteins