Staphylococcus aureus colonization and the risk of infection in critically ill patients.
OBJECTIVE
To evaluate the relationship between Staphylococcus aureus nasal and tracheal colonization and infection in medical intensive care unit (MICU) patients. The primary outcome was the incidence of S. aureus infection in colonized versus non-colonized patients.


METHODS
Prospective, observational cohort study. Patients admitted to the MICU during the study period were screened for S. aureus nasal and tracheal colonization by culture and a PCR assay twice weekly. Demographic, clinical, and microbiologic data were collected in the MICU and for 30 days after discharge. PFGE and antibiotic susceptibility testing were performed on all S. aureus nasal, tracheal, and clinical isolates.


RESULTS
Twenty-three percent of patients (47 of 208) were nasally colonized with S. aureus. Twenty-four percent of these patients developed S. aureus infections versus 2% of non-colonized patients (P < .01). Nine of 11 patients with both nasal colonization and infection were infected by their colonizing strain. Two of 47 nasally colonized patients developed an infection with a different strain of S. aureus. Fifty-three percent of intubated patients with nasal colonization (10 of 19) had tracheal colonization with S. aureus as opposed to 4.9% of intubated, non-colonized patients (3 of 61) (P < .01). Parenteral antibiotics were ineffective at clearing nasal colonization. PCR detected S. aureus colonization (nasal and tracheal) within 6.5 hours with a sensitivity of 83% and a specificity of 99%.


CONCLUSIONS
The incidence of S. aureus infection was significantly elevated in nasally colonized MICU patients. Techniques to rapidly detect colonization in this population may make targeted topical prevention strategies feasible.
Keene
Adam
A
Division of Infectious Diseases, Columbia University College of Physicians & Surgeons, New York, New York, USA. adambkeene@hotmail.com
Vavagiakis
Peter
P
Lee
Mei-Ho
MH
Finnerty
Kathryn
K
Nicolls
Deborah
D
Cespedes
Christian
C
Quagliarello
Bianca
B
Chiasson
Mary Ann
MA
Chong
David
D
Lowy
Franklin D
FD
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D015331:Cohort Studies; D003428:Cross Infection / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data; D016106:Methicillin Resistance; D008875:Middle Aged; D009519:New York City / Q000453:epidemiology; D009666:Nose / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D014132:Trachea / Q000382:microbiology; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents