Are laboratory-based antibiograms reliable to guide the selection of empirical antimicrobial treatment in patients with hospital-acquired infections?
OBJECTIVE
Antibiograms are often taken into account to define a rational selection of an empirical antimicrobial therapy for treating patients with hospital-acquired infections. In this study, we performed a paired comparison between the antibiogram constructed with laboratory-based data and that formed with data subjected to prior clinical validation.


METHODS
Between 2003 and 2005, the laboratory of microbiology printed in duplicate every individual susceptibility report corresponding to hospitalized patients and the copy was sent to the department of infection control. Every individual report was assessed in real time at the bedside of the patient by a multidisciplinary team for clinical significance and appropriateness of the specimen, as well as for the type, source and origin of the infection. Cumulative resistance rates were estimated in parallel at the laboratory with the whole data, and at the infection control department with data subjected to prior clinical validation. These rates were designated as 'laboratory-based' and 'clinically based', respectively.


RESULTS
A total of 2305 individual susceptibility reports were assessed. Only 1429 (62.0%) were considered as clinically significant by the multidisciplinary team. Escherichia coli, Enterobacter cloacae, Citrobacter freundii group, Klebsiella species and Proteus mirabilis resistant to broad-spectrum cephalosporins, as well as methicillin-resistant Staphylococcus aureus, were significantly more frequent in the clinically based rates (P < or = 0.03).


CONCLUSIONS
Laboratory-based data underestimate the frequency of several major resistant organisms in patients with hospital-acquired infection. Previous clinical validation of the individual susceptibility reports seems to be a suitable strategy to get more reliable data.
Bantar
Carlos
C
Department of Infection Control, Hospital San Martín, Perón 450 (3100) Paraná, Entre Ríos, Argentina. cbantar@arnet.com.ar
Alcazar
Gabriela
G
Franco
Diego
D
Salamone
Francisco
F
Vesco
Eduardo
E
Stieben
Teodoro
T
Obaid
Florencia
F
Fiorillo
Alejandro
A
Izaguirre
Mariano
M
Oliva
María Eugenia
ME
D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000188:drug therapy*; D003428:Cross Infection / Q000188:drug therapy*; D024881:Drug Resistance, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests
D000900:Anti-Bacterial Agents