Macroscopic purulence, leukocyte counts, and bacterial morphotypes in relation to culture findings for sinus secretions in acute maxillary sinusitis

Abstract

Macroscopic purulence, leukocyte counts, and bacterial morphotypes in Gram-stained smears were investigated in 335 sinus secretions (240 aspirates and 95 injection aspirates) obtained by puncture in 234 young patients with acute maxillary sinusitis. Over 90% of the 147 aspirates macroscopically classified as purulent also contained high numbers of leukocytes (>20 per oil immersion field). A total of 82% of the 147 macroscopically purulent aspirates and 79% of the 156 aspirates containing high numbers of leukocytes yielded presumed sinus pathogens by culture in quantities of >103 CFU/ml. Streptococcus pneumoniae or Streptococcus pyogenes was associated relatively more often (92 or 87%, respectively) with high numbers of leukocytes than Haemophilus influenzae, which was not infrequently (29%) recovered from the less purulent aspirates. When a bacterial morphotype was seen in the Gram-stained smear, a corresponding sinus pathogen was isolated in quantities of >103 CFU/ml in 92% of aspirates. Other bacterial species (most often staphylococci) were usually isolated in low numbers and were almost never seen in the smear, suggesting nasal contamination. The 95 injection aspirates behaved, to a large extent, like diluted aspirates, with the exception that there was a higher frequency of probable nasal contamination. Macroscopic purulence, high leukocyte counts, and bacterial morphotypes seen in Gram-stained smears each predicted well the isolation of a presumed sinus pathogen and in some cases supported the significance of an otherwise doubtful culture finding. However, the macroscopic appearance of the secretion should not be used to screen samples for culture, because in several cases H. influenzae grew from nonpurulent samples as well.