OBSERVATIONS ON BACTERIOPHAGE TYPING OF PSEUDOMONAS AER UGINOSA

Recent reports indicate that there have been increasing numbers of serious infections due to Pseudomonas aeruginosa during the past few years (1-3). This has also been true at this hospital where the number of cases of bacteremic infection with this organism and of deaths in such cases has been steadily increasing since the introduction of potent antibacterial agents (4). Ps. aeruginosa has become one of the most important infectious agents, rivaling the staphylococcus as a cause of septicemia and death in patients with burns (5-7); it is being found frequently in infected surgical wounds (8), and outbreaks of serious and fatal infections with this organism have been reported in nurseries (9). It causes notoriously intractable urinary tract infections (10, 11), and it is being recognized as a major cause of serious and fatal superinfections in patients under intensive treatment with multiple or broad spectrum antibiotics (12-14). Most recently it has proved to be a major cause of bacteremia and death in patients under treatment for staphylococcal infections with methicillin (dimethoxyphenyl penicillin) (15-17). Most of the pseudomonas infections seem to arise in hospitals (12, 18, 19) and some studies have implicated inhalation of humid air (20-22) and contaminated water (23) as sources of isolated outbreaks in nurseries, but the sources of most of the sporadic infections within hospitals remain obscure. The use of bacteriophage typing for the characterization of strains within certain genera of bacteria is now well known and has had many applications (24). This method, applied to strains of Staphylococcus aureus has proved particularly useful in recent years for the identification of sources of endemic and epidemic spread of infections with this organism, particularly in nurserie