International Journal of Pediatric Otorhinolaryngology, 23 (1992) 15-23 Elsevier Science Publishers B.V. 15 PEDOT 00747 Effect of respiratory syncytial virus on adherence, colonization and immunity of non-typable Haemophilus influenzae: implications for otitis media J. Pate1 *, H. Faden, Sanjay Sharma and P.L. Ogra * * Department of Pediatrics, State University of New York School of Medicine at Buffalo, Buffalo, NY (U.S.A.) and Division of Infectious Diseases, The Children’s Hospital of Buffalo, Buffalo, NY 14222 (U.S.A.) (Received 9 October 1990) (Revised version received 13 March 1991) (Accepted 13 March 1991) Key words: Non-typable Haemophilus influenzae; Otitis media; Nasopharyngeal colonization; Bacterial adherence; Respiratory syncytial virus Abstract Adherence of non-typable Huemophilus influenzae to respiratory epithelium was evaluated in a cotton rat model of respiratory syncytial virus (RSV) infection. Colonization with non-typable H. influenzae increased to a maximum within 4 days of RSV infection compared to RSV negative controls (4.58 + 0.17 vs 3.82 + 0.23 log colony forming units (CFU) per ml, P < 0.05) and then declined over the subsequent 10 days (2.0 k 0 vs 3.78 -t 0.39 CFU per ml, P < 0.0001). In a second series of experiments, attachment of non-typable H. influenzae to epithelial cells collected from RSV infected cotton rats at the time of maximum virus replication was not different from controls (57.4 f 18.3 vs 52.0 + 24.3 bacteria per 50 cells). Systemic immunity to non-typable H. influenzue as measured by IgG-specific antibody to the outer membrane complex and bactericidal antibody did not influence colonization. These data suggest that colonization with non-typable H. influenzae is significantly affected by a concurrent infection with RSV; however, the site of bacterial attachment is not known, * Present address: Department of Pediatrics, Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77550, U.S.A. * * Present address: Department of Pediatrics, University of Texas Medical Branch at Galveston, Child Health Center C3-3, Galveston, TX 77550, U.S.A. Correspondence: H. Faden, Division of Infectious Diseases, Children’s Hospital, 219 Bryant Street, Buffalo, NY, 14222, U.S.A.