Effect of antimicrobial use on pneumococcal diagnostic tests in elderly patients with community-acquired pneumonia

• DOI: 10.1007/s10096-014-2278-5
• Publication Date: 2014-11-21T14:32:30Z
• Authors: A. Saukkoriipi; A. A. Palmu; J. Jokinen; V. Verlant; W. P. Hausdorff; T. M. Kilpi
• Keywords: Aged, 80 and over; Male; Antigens, Bacterial; Diagnostic Tests, Routine; Sputum; Pneumonia, Pneumococcal; Urinalysis; Antibodies, Bacterial; Polymerase Chain Reaction; Sensitivity and Specificity; 6. Clean water; Anti-Bacterial Agents; 3. Good health; Community-Acquired Infections; 03 medical and health sciences; Streptococcus pneumoniae; 0302 clinical medicine; Nasopharynx; Humans; Female; Aged

Antimicrobial treatment decreases bacterial culture yields. We assessed the impact of antimicrobial treatment on pneumococcal assays in a prospective study of community-acquired pneumonia (CAP) in the elderly. We enrolled 323 cases aged ≥65 years with radiologically confirmed CAP and collected detailed data on antimicrobial exposure and pneumococcal assays on various samples. Complete antimicrobial use data were available for 303 (94%) cases; 61% had no antimicrobial exposure, 19% had received antibiotics at the acute visit only, and 20% within 2 weeks before the acute visit (15% ongoing and 5 % completed treatment). Ongoing use before the visit reduced pneumococcal detection by culture (nasopharyngeal swab 2 vs. 16% in the unexposed; high-quality sputum 0 vs. 25%) and sputum lytA polymerase chain reaction (PCR) (0 vs. 25%). Urine antigen test and serology were not affected. Among those who had received antibiotics only at the acute visit before study sampling, serology (29 vs. 15%), urine antigen (19 vs. 8%), and blood culture (9 vs. 2%) were more often positive than among the unexposed. Antimicrobial exposure before the visit reduced both culture and PCR-based detection. Patients given antibiotics at the visit had higher proportions of positive blood culture, serology, and urine antigen tests, suggesting higher pneumococcal CAP prevalence.