Risk factors for methicillin-resistance among patients with Staphylococcus aureus bacteremia at the time of hospital admission.
BACKGROUND
Community-acquired infections caused by methicillin-resistant Staphylococcus aureus (MRSA) seem to be increasing. Characteristics permitting recognition of patients with such strains would aid infection control efforts and choice of empiric therapy pending culture and susceptibility results.


METHODS
Retrospective review of medical records for all adults seen in the Emergency Care Center at Grady Memorial Hospital, Atlanta, Georgia, whose blood cultures taken within 24 hours of entry yielded S. aureus. Risk factors for the presence of methicillin resistance in S. aureus isolates recovered from patients with staphylococcal bacteremia were assessed.


RESULTS
S. aureus isolates from 118 (40%) of 297 study patients with bacteremia at the time of admission were methicillin-resistant. Multivariate analysis identified hospitalization in the 6 months preceding admission [odds ratio (OR) = 4.4; 95% CI, 2.0-9.8], receipt of antimicrobial agents in the past 3 months (OR = 5.6; 95% CI, 2.6-11.9], presence of indwelling urinary catheter (OR = 7.3; CI, 2.5-20.9), and nursing home residence (OR = 9.9; 95% CI, 3.9-25.6) to be independently associated with the presence of methicillin resistance. All but 4 of the 118 patients with methicillin-resistant strains had at least 1 of these factors and the proportion of resistant isolates progressively increased as more of these features were present.


CONCLUSIONS
The presence of these risk factors should be considered when making decisions about isolation and other infection control procedures as well as empiric antimicrobial therapy with vancomycin for patients with suspected staphylococcal infection at the time of hospital admission. Similar studies could guide practices for dealing with such patients in other centers, because the occurrence of MRSA infections at the time of admission may vary widely by geographic area.
Rezende
Nilton A
NA
Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
Blumberg
Henry M
HM
Metzger
Brian S
BS
Larsen
Nina M
NM
Ray
Susan M
SM
McGowan
John E
JE
D000293:Adolescent; D000328:Adult; D016470:Bacteremia / Q000188:drug therapy / Q000382:microbiology* / Q000503:physiopathology; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008712:Methicillin / Q000494:pharmacology* / Q000627:therapeutic use; D016106:Methicillin Resistance; D008875:Middle Aged; D010406:Penicillins / Q000494:pharmacology / Q000627:therapeutic use; D012189:Retrospective Studies; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology* / Q000503:physiopathology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification
D010406:Penicillins; D008712:Methicillin