Influence of penicillin resistance on outcome in adult patients with invasive pneumococcal pneumonia: is penicillin useful against intermediately resistant strains?
OBJECTIVE
To compare outcome between patients with pneumonia due to penicillin-susceptible S. pneumoniae and patients with pneumonia due to penicillin intermediately resistant strains and to study the outcome of patients with pneumococcal pneumonia caused by strains with MICs of 0.12-1 mg/L treated empirically during the first 48 h with beta-lactam antibiotics.


METHODS
We studied 247 adult patients with invasive pneumococcal pneumonia occurring from 1997 to 2001. The following data were recorded from each patient: socio-demographic characteristics, underlying diseases, clinical presentation, initial severity of pneumonia, initial and subsequent antimicrobial therapy, in-hospital complications, hospital mortality and length of hospital stay. Multivariate analysis was done to identify variables associated with the development of pneumonia caused by a non-susceptible strain.


RESULTS
The overall presence of penicillin non-susceptibility was 26.7%; no strain had an MIC >2 mg/L. Overall mortality was 23.5% in patients with pneumonia caused by intermediately resistant pneumococci and 12.7% in those with pneumonia caused by susceptible strains (P=0.075). Mortality during the first 7 days of admission, considered to be pneumonia-related deaths (13.7% versus 9.9%; P=0.448) was similar in both groups. The multivariate analysis showed that serotype 14 (OR, 140.18; 95% CI, 16.95-1159.20), serotype 19 (OR, 7.53; 95% CI, 1.98-28.7), haematological malignancy or splenectomy (OR, 4.46; 95% CI, 1.5-13.23) and HIV infection (OR, 4.54; 95% CI, 1.54-13.44) were the only independent factors associated with pneumonia caused by penicillin intermediately resistant pneumococci. In patients with strains having MICs of 0.1-1 mg/L, overall mortality was similar in the group of penicillin-treated patients (22.2%) to those treated with broad-spectrum beta-lactams (23.5%).


CONCLUSIONS
There is a non-significant trend to higher mortality in patients with pneumococcal pneumonia caused by intermediately resistant strains; however, they do not have a poorer outcome when they are treated with amoxicillin.
Falcó
Vicenç
V
Infectious Disease Department, Hospitals Vall d'Hebron, Universitat Autònoma de Barcelona, P degrees Vall d'Hebron 119-129, 08035 Barcelona, Spain. vfalco@vhebron.net
Almirante
Benito
B
Jordano
Queralt
Q
Calonge
Laura
L
del Valle
Oscar
O
Pigrau
Carles
C
Planes
Ana María
AM
Gavaldà
Joan
J
Pahissa
Albert
A
D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D003422:Critical Care; D004917:Erythromycin / Q000494:pharmacology; D005260:Female; D006760:Hospitalization; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000150:complications; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015999:Multivariate Analysis; D010403:Penicillin Resistance; D010406:Penicillins / Q000627:therapeutic use*; D010994:Pleura / Q000382:microbiology; D011018:Pneumonia, Pneumococcal / Q000188:drug therapy* / Q000382:microbiology / Q000401:mortality; D018570:Risk Assessment; D013030:Spain / Q000453:epidemiology; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D010406:Penicillins; D004917:Erythromycin; D000658:Amoxicillin