RT Journal Article SR Electronic T1 Histamine synthesis by respiratory tract micro-organisms: possible role in pathogenicity. JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 516 OP 522 DO 10.1136/jcp.42.5.516 VO 42 IS 5 A1 Devalia, J L A1 Grady, D A1 Harmanyeri, Y A1 Tabaqchali, S A1 Davies, R J YR 1989 UL http://jcp.bmj.com/content/42/5/516.abstract AB Five bacterial species considered to be potential pathogens in acute exacerbations of chronic bronchitis, cystic fibrosis, and pneumonia--Branhamella catarrhalis, Haemophilus parainfluenzae, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pneumoniae--were evaluated for their potential to synthesise histamine in vitro. Bacterial species commonly isolated from infected sputum but generally not considered to be pathogenic--Enterobacteriacae, Neisseria pharyngis, coagulase negative staphylococci, alpha-haemolytic streptococci, and Candida albicans--were similarly studied. Of the "pathogens", the Gram negative species B catarrhalis, H parainfluenzae and Ps aeruginosa synthesised clinically important amounts of histamine; this was not the case for the Gram positive species S aureus and S pneumoniae. Of the "non-pathogenic" species, only the Enterobacteriacae, as a group, were found to synthesise clinically important amounts of histamine. These results show that some Gram negative bacteria, associated with acute exacerbations in respiratory infections, produce histamine and possibly other inflammatory mediators, which may contribute to their pathogenecity in the lower respiratory tract in vivo.