Companion articles in this issue of The Journal (pp 2157 and 2190) retell the story of the ubiquitous Serratia marcescens, long believed to be a nonpathogenic pigment producer. Especially during the last decade, a number of authors have dispelled misconceptions; S marcescens does indeed cause infections (some of them quite serious), and the great majority of strains are not chromogenic. The latter fact, as implied by Wilkowske et al, may be the reason for the earlier belief in the innocuousness of Serratia; without the utmost refinement of bacteriological technique, the organism is easily mistaken for another species of Enterobacter.
Serratia infections are likely to occur in the elderly, the debilitated, the hospitalized patients. In the experience of Wilkowske's group, 98 of 176 patients acquired Serratia infections after hospitalization. The two most important antecedent conditions were surgical operation and antimicrobial therapy. The authors mention frequent contamination of irrigating solutions, inhalation therapy
Serratia marcescens Endocarditis. JAMA. 1970;214(12):2185. doi:10.1001/jama.1970.03180120057010