Direct examination and cultures of bronchoalveolar lavage in pneumonia diagnosis: a comparative experimental study.
OBJECTIVE
To assess the accuracy of direct examination and quantitative cultures of BAL to diagnose pneumonia with or without antibiotic treatment.


METHODS
Experimental rat models.


METHODS
Pneumonia was induced by intratracheal inoculation of S. pneumoniae (10(9) cfu/ml) or P. aeruginosa (10(8)cfu/ml). Controls (n = 10) received sterile inoculum. Study animals received penicillin (n = 19) or saline (n = 18) (pneumococcal model); amikacin (n = 13), ceftazidime (n = 11), or saline (n = 13) (Pseudomonas model). BAL was assessed 48 h after infection. The animals were killed for histopathological analysis.


RESULTS
All study animals developed pneumonia, which was more extensive in the pneumococcal than in the Pseudomonas model. In pneumococcal pneumonia the sensitivity of BAL cultures (10(3) cfu/ml or higher) was 77.8% with saline and 21.0% with penicillin. In the Pseudomonas ceftazidime group all specimens were negative, precluding diagnosis. The sensitivity of cultures with amikacin was 23.1% vs. 30.8% with saline. In the pneumococcal model intracellular organism (ICO) count of 2% or higher had a sensitivity of 100% for detecting pneumonia with saline and 57.9% with penicillin. In the Pseudomonas model the sensitivity of ICO was 69.2% with both amikacin and saline and 36.3% with ceftazidime. The sensitivity of neutrophil count above 50% in pneumococcal pneumonia was 77.8% and 64.7% with saline and penicillin, respectively, and 69.2%, 61.5%, and 81.8% with saline, amikacin, and ceftazidime, respectively, in Pseudomonas pneumonia.


CONCLUSIONS
BAL-positive intracellular organisms were more accurate than cultures for the diagnosis of recent pneumonia, and were less affected by antibiotic treatment.
Centro de Terapia Intensiva, Hospital Moinhos de Vento, 90035-001, Porto Alegre RS, Brazil. brandao@hmv.org.br
Nilton
N
Brandão da Silva
Lucas
L
Martins
Frederico
F
Martins
José
J
Anflor
Tiago
T
Tonietto
Cristiano
C
Koefender
Paulo G
PG
Cardoso
José
J
Moreira
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001431:Bacteriological Techniques; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology* / Q000382:microbiology; D015169:Colony Count, Microbial; D008168:Lung / Q000382:microbiology / Q000473:pathology; D018410:Pneumonia, Bacterial / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology* / Q000473:pathology; D011018:Pneumonia, Pneumococcal / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology; D011552:Pseudomonas Infections / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae / Q000302:isolation & purification
D000900:Anti-Bacterial Agents