Matched case-control analysis of polymicrobial bloodstream infection in a neonatal intensive care unit.
OBJECTIVE
To compare and contrast the epidemiology of polymicrobial and monomicrobial bloodstream infections (BSIs) in newborn intensive care unit (NICU) patients.


METHODS
Retrospective, matched case-control study.


METHODS
The Yale-New Haven Hospital NICU from 1989 through 2006.


METHODS
NICU patients with BSIs.


METHODS
Each neonate with polymicrobial BSI (case patient) was matched to one neonate with monomicrobial BSI (control patient), by birth date, weight, and sex; and univariate and multivariate analyses were performed.


RESULTS
One hundred five cases of polymicrobial BSI were identified in 102 infants, representing 10% of all neonatal BSIs in our institution. Coagulase-negative staphylococci were the most common organisms recovered from culture. Infants with polymicrobial BSI had later onset of infection than infants with monomicrobial BSI (mean day of life, 37.5 vs 24.0; P<.001). Polymicrobial BSI occurred more frequently among infants with a severe underlying condition than in those without such a condition (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.1-3.2) and among infants requiring an indwelling central venous catheter for a prolonged duration (mean, 16.9 days, compared with 9.8 days for infants with monomicrobial BSI; P=.001). Multivariate analysis revealed that later onset of infection (adjusted OR [aOR], 1.02; 95% CI, 1.00-1.04) and presence of a severe underlying condition (aOR, 1.91; 95% CI, 1.12-3.38) were independent risk factors for polymicrobial BSI. No differences in outcome or mortality were observed.


CONCLUSIONS
Changes in the microbiology and epidemiology of NICU-related polymicrobial BSI have occurred since the last North American review. In the present study, although differences were observed, most risk factors and outcomes were similar between monomicrobial BSI and polymicrobial BSI. Epidemiologic surveillance is critical to identify trends associated with neonatal polymicrobial BSI, particularly those that may impact preventative strategies, diagnostic measures, and therapeutic interventions.
Bizzarro
Matthew J
MJ
Division of Perinatal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8064, USA.
Dembry
Louise-Marie
LM
Baltimore
Robert S
RS
Gallagher
Patrick G
PG
D016470:Bacteremia / Q000150:complications / Q000453:epidemiology / Q000382:microbiology; D016022:Case-Control Studies; D005260:Female; D016469:Fungemia / Q000150:complications / Q000453:epidemiology / Q000382:microbiology; D005658:Fungi / Q000145:classification / Q000302:isolation & purification; D006090:Gram-Negative Bacteria / Q000145:classification / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000150:complications / Q000453:epidemiology / Q000382:microbiology; D006094:Gram-Positive Bacteria / Q000145:classification / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000150:complications / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D015994:Incidence; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology / Q000382:microbiology; D019102:Infant, Very Low Birth Weight; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data*; D008297:Male; D012307:Risk Factors