Bacterial Infection and Hospital Infection of Patients with Influenza.

THOUGH the atiology of influenza has for 30 years been the concern of virus workers, the secondary ravages of bacteria are still recognized to be a very important feature of the disease. I shall not attempt a wide survey of this subject, which would take me far outside my own province, but will consider the role of bacteria in patients admitted to hospital with influenza during recent outbreaks, with particular reference to prevention and treatment of secondary staphylococcal infections. The importance of Staphylococcus aureus as a cause of pneumonia complicating influenza was reported from many sources during the Asian influenza epidemic of I957. For instance, the Public Health Laboratory Service (1958) described the isolation of staphylococci from the lungs or sputum of 62% of 477 patients who died from pneumonia during the epidemic; the staphylococcus was held responsible for most of the deaths in young, healthy patients. Oswald, Shooter and Curwen (1958) reported a mortality of 28% in 155 cases of staphylococcal pneumonia complicating influenza, compared with a mortality of i2% in 145 patients with non-staphylococcal pneumonia; the high mortality of the staphylococcal cases appeared in all age-groups, whereas the mortality of the non-staphylococcal pneumonia was highest (26%) in patients of 55 years of age or more, and low (o to 3%) in the lower age groups. In most reports Staphylococcus aureus appeared to be the worst bacterial invader, though not necessarily the commonest; indeed Forbes (1958) found Staphylococcus aureus in only five out of 34 fatal cases with bacterial complications, both pneumococci and Streptococcus pyogenes being commoner. The majority of staphylococcal infections are brought in, rather than acquired in hopital, by patients admitted with influenza (e.g. Public Health Laboratory Service, I958), but those who are admitted commonly acquire hospital strains of staphylococci. Oswald and his colleagues (I958) (Table i) found a much higher proportion of staphylococci of hospital type resistant to penicillin and tetracycline in the sputum of influenzal pneumonia patients after they had been in the ward for several days than in their first days after admission; a relative increase of hospital phage types was shown in a similar comparison by TABLE I SENSITIVITIES OF STAPHYLOCOCCI FROM INFLUENZA PATIENTS IN HOSPITAL WITH STAPHYLOCOCCAL PNEUMONIA