EAR INFECTIONS 329 



Various fly larvae are far more common, and the " screw- worm," 

 the larva of the Chrysomyia macellaria, is common in certain parts 

 of tropical America, and may by its burrowing effects cause fatal results. 



The larvae of Sarcophaga have in particular been found in the nasal cavities of 

 children. Myriapods, while of very little importance elsewhere, have been reported 

 more than thirty times from the nasal fossae. 



In a study of the bacteriology of otitis media, in 277 cases, Libman 

 and Celler found streptococci present alone in 81%, streptococcus 

 mucosus in 10% and the pneumococcus in 8%; staphyococci, B. pyo- 

 cyaneus and B. proteus have also been found. Mixed infections are 

 common. 



Streptococci are the organisms which most often cause sinus thrombosis and brain 

 abscess. The influenza bacillus has been reported as a cause of acute otitis media. 



Nonvirulent diphtheroid bacilli are not infrequently obtained in cultures from 

 ear discharges. 



Other organisms which have been isolated from middle ear or mastoid discharges 

 are B. coli, M. catarrhalis, M. tetragenus and Friedlander's bacillus. 



B. typhosus may be found in middle-ear discharges of persons who have had an 

 attack of typhoid fever. 



The middle ear is normally free of bacteria, but in affections of the throat, as 

 with streptococci, pneumococci, and diphtheria bacilli, these organisms may infect 

 it by way of the Eustachian tube. 



The moulds are of greater importance in affections of the external auditory canal 

 than the bacteria. The cerumen seems to make a good culture medium so that 

 various species of Aspergillus, Mucor, etc., develop and close the canal. These 

 infections are often introduced by the patient's finger. Various mites and fly larvae 

 have been reported from the ear. 



