Impairment of polymorphonuclear neutrophil functions precedes nosocomial infections in critically ill patients.
OBJECTIVE
A postinjury immunodepression involving neutrophil functions has been described in critically ill patients. The aim of this prospective study was to search for a relationship between an impairment of neutrophil functions and the subsequent development of nosocomial infection.


METHODS
Twenty-one severely ill (simplified acute physiology score II >20 on admission), nonimmunosuppressed patients who were receiving no antibiotics active against methicillin-resistant Staphylococcus aureus and highly resistant Pseudomonas aeruginosa were included. Twelve healthy subjects constituted a control group.


METHODS
Neutrophil functions (phagocytosis and bactericidal activity toward S. aureus and P. aeruginosa in homologous plasma, reactive oxygen species secretion) were studied at day 4 +/- 1 after admission, and occurrence of nosocomial infection was prospectively recorded over the following 5 days. Interleukin-10 concentration was assessed by enzyme-linked immunosorbent assay. Results are expressed as median (25th-75th percentiles).


RESULTS
Six out of the 21 patients acquired a nosocomial infection during the 5 days after blood sampling (infected group). Compared with the patients who did not acquire nosocomial infection (noninfected group, n = 15), the neutrophils of the infected group demonstrated a higher percentage of intracellular bacterial survival (17% [2% to 67%] vs. infected: 62% [22% to 100%], p <.05), leading to an impairment of S. aureus killing in homologous plasma (killed bacteria: 4.93 log(10) colony forming units/mL [4.24-5.29] vs. infected: 3.62 log(10) colony forming units/mL [0.00-4.58], p <.05). Interleukin-10 plasma concentration was higher in infected patients (78 pg/mL [60-83]) compared with noninfected patients (22 pg/mL [14-58], p <.05). By contrast, P. aeruginosa killing was similar in patients whether or not they acquired a nosocomial infection.


CONCLUSIONS
A decrease in S. aureus killing capabilities of neutrophils can be evidenced within the days before occurrence of a nosocomial infection.
Stephan
François
F
Surgical Intensive Care Unit, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris, Paris, France.
Yang
Kun
K
Tankovic
Jacques
J
Soussy
Claude-James
CJ
Dhonneur
Gilles
G
Duvaldestin
Philippe
P
Brochard
Laurent
L
Brun-Buisson
Christian
C
Harf
Alain
A
Delclaux
Christophe
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001770:Blood Bactericidal Activity; D003428:Cross Infection / Q000453:epidemiology / Q000276:immunology*; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D066298:In Vitro Techniques; D016753:Interleukin-10 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000276:immunology / Q000382:microbiology*; D010587:Phagocytosis / Q000276:immunology*; D011552:Pseudomonas Infections / Q000453:epidemiology / Q000276:immunology*; D017382:Reactive Oxygen Species / Q000097:blood; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000276:immunology*; D018709:Statistics, Nonparametric
D015850:Interleukin-6; D017382:Reactive Oxygen Species; D016753:Interleukin-10