Is methicillin resistance associated with a worse prognosis in Staphylococcus aureus ventilator-associated pneumonia?
BACKGROUND
Excess mortality associated with methicillin resistance in patients with Staphylococcus aureus ventilator-associated pneumonia (SA-VAP), taking into account such confounders as treatment adequacy and time in the intensive care unit (ICU), have not been adequately estimated.


METHODS
One hundred thirty-four episodes of SA-VAP entered in the Outcomerea database were studied. Patients from whom methicillin-resistant S. aureus (MRSA) was recovered were compared with those from whom methicillin-susceptible S. aureus (MSSA) was recovered, stratified for duration of stay in the ICU at the time of VAP diagnosis and adjusted for confounders (severity at admission, characteristics at VAP diagnosis, and treatment adequacy).


RESULTS
Treatment was adequate within 24 h after VAP diagnosis for 86% of the 65 MSSA-infected patients and 77% of the 69 MRSA-infected patients (P = .2). Polymicrobial VAP was more commonly associated with MSSA than with MRSA (49.2% vs. 25.7%; P = .01). MRSA infection was associated with a lower prevalence of coma at hospital admission and a higher rate of use of central venous lines and fluoroquinolones during the first 48 h of the ICU stay. The rates of shock, recurrence, and superinfection were similar in both groups. The crude hospital mortality rate was higher for MRSA-infected patients than for MSSA-infected patients (59.4% vs. 40%; P = .024). This difference disappeared after controlling for time in the ICU before VAP and parameters imbalanced at ICU admission (odds ratio [OR], 1.23; 95% confidence interval [CI], 0.49-3.12; P = .7) and remained unchanged after further adjustments for initial treatment adequacy and polymicrobial VAP (OR, 0.98; 95% CI, 0.36-2.66).


CONCLUSIONS
Differences in patient characteristics, initial ICU treatment, and time in the ICU confounded estimates of excess death due to MRSA VAP. After careful adjustment, methicillin resistance did not affect ICU or hospital mortality rates.
Zahar
Jean-Ralph
JR
Department of Microbiology, Necker Teaching Hospital, Paris, France.
Clec'h
Christophe
C
Tafflet
Muriel
M
Garrouste-Orgeas
Maite
M
Jamali
Samir
S
Mourvillier
Bruno
B
De Lassence
Arnaud
A
Descorps-Declere
Adrien
A
Adrie
Christophe
C
Costa de Beauregard
Marie-Alliette
MA
Azoulay
Elie
E
Schwebel
Carole
C
Timsit
Jean-Francois
JF
D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D011023:Pneumonia, Staphylococcal / Q000188:drug therapy* / Q000209:etiology / Q000401:mortality*; D011379:Prognosis; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000009:adverse effects*