title: Nasal carriage of methicillin resistant staphylococci.
abstract: Coagulase-negative staphylococci (CoNS) are believed to function as reservoirs, as well as possible sources of staphylococcal chromosome cassette mec (SCCmec) to Staphylococcus aureus, but the frequency, preferred partners, and factors promoting SCCmec transfer are not known. Such postulated in vivo genetic transfer events are likely to occur at anatomical sites such as the normal nasal mucosa, which is known to be colonized by both CoNS and coagulase positive staphylococci. In this study, we characterized S. aureus and CoNS strains colonizing the anterior nares of 67 patients in Denmark. A total of 54 patients (80%) were colonized with staphylococci that included nine different species identified by internal transcribed spacer PCR (ITS-PCR) and 16S RNA sequencing. The highest rates of colonization were found for S. epidermidis (58%) and S. aureus (39%). Methicillin resistance was present in S. aureus (53%), S. epidermidis (53%), S. haemolyticus (33%), and S. hominis (62%). Genetic backgrounds were characterized by spa typing for S. aureus and by pulsed-field gel electrophoresis for CoNS. SCCmec typing showed that SCCmec type IV (2B) was the most common in the entire collection (65%). Carriage of multiple species was detected in 20 patients (30%), 16 of whom were colonized with both S. aureus and S. epidermidis. In two cases, simultaneous carriage of different methicillin resistant species was detected. However, the strains carried different SCCmec types. Additional studies in the same epidemiological settings are warranted to identify interspecific genetic events that involve the acquisition of SCCmec by S. aureus.
authors.affiliation: 1 Laboratorie of Molecular Genetics, Instituto de Tecnologia Química e Biológica (ITQB) , Oeiras, Portugal .
authors.forename: Nuno A
authors.initials: NA
authors.lastname: Faria
authors.forename: Teresa
authors.initials: T
authors.lastname: Conceição
authors.forename: Maria
authors.initials: M
authors.lastname: Miragaia
authors.forename: Mette Damkjær
authors.initials: MD
authors.lastname: Bartels
authors.forename: Hermínia
authors.initials: H
authors.lastname: de Lencastre
authors.forename: Henrik
authors.initials: H
authors.lastname: Westh
mesh_terms: D000328:Adult; D015373:Bacterial Typing Techniques; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002876:Chromosomes, Bacterial; D021901:DNA, Intergenic / Q000235:genetics; D003718:Denmark / Q000453:epidemiology; D022761:Gene Transfer, Horizontal; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification; D008875:Middle Aged; D009666:Nose / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000235:genetics / Q000302:isolation & purification; D041162:Staphylococcus haemolyticus / Q000235:genetics / Q000302:isolation & purification; D041181:Staphylococcus hominis / Q000235:genetics / Q000302:isolation & purification
chemical_list: D021901:DNA, Intergenic; D012336:RNA, Ribosomal, 16S