A molecular epidemiological analysis of 2 Staphylococcus aureus clonal types colonizing and infecting patients with AIDS.
BACKGROUND
Persons with acquired immune deficiency syndrome (AIDS) who use drugs appear to be at increased risk for colonization and infection with Staphylococcus aureus. Little is known about the nature of and risk factors responsible for this association. This study is among the first to prospectively follow carriage and infection in this uniquely high-risk population.


METHODS
We prospectively followed the cases of 75 patients with AIDS in a residential drug treatment facility and screened for S. aureus nasal colonization and infection.


RESULTS
Thirty-seven baseline cultures (49%) were positive for S. aureus, and 81% of subjects were colonized at least once during the study. Thirteen subjects experienced 17 infections. Pulsed-field gel electrophoresis and sequence-based typing methods revealed that 244 (92%) of the isolates belonged to either clonal type A or B. Clonal type A was methicillin-susceptible. Clonal type B consisted of 3 main subtypes (B1, B2, and B3), all with the same allelic profile (ST8) and staphylococcal protein A gene (spa) type (7). Of note, subtype B1 was methicillin-susceptible (ST8 and spa type 7), lacking mecA, whereas the other B clones were methicillin-resistant. Both clones were resistant to trimethoprim-sulfamethoxazole. Clonal type B isolates were relatively resistant, suggesting prior exposure to the health care setting.


CONCLUSIONS
This study demonstrates a sustained high rate of S. aureus carriage and infection. It demonstrates the capacity of unique methicillin-resistant S. aureus clones with an established linkage to earlier outbreaks of methicillin-resistant S. aureus, as well as to human immunodeficiency virus--infected subjects, to persist in this residential setting. It also illustrates the apparent genetic instability or transmissibility of the staphylococcal chromosomal cassette mec type IV element.
Gordon
Rachel J
RJ
Division of Infectious Diseases, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, USA.
Quagliarello
Bianca
B
Cespedes
Christian
C
Chung
Marilyn
M
de Lencastre
Herminia
H
Vavagiakis
Peter
P
Miller
Maureen
M
Zeller
Barbara
B
Lowy
Franklin D
FD
D000163:Acquired Immunodeficiency Syndrome / Q000150:complications*; D000328:Adult; D000900:Anti-Bacterial Agents; D002353:Carrier State; D024881:Drug Resistance, Bacterial; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D009666:Nose / Q000382:microbiology; D010641:Phenotype; D010802:Phylogeny; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000209:etiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents