A Retrospective Analysis of Joint Cultures: Only Time Will Tell (Or Will It?)

Abstract

Abstract Introduction/Objective Multiple textbooks and guidelines, including CLSI, recommend holding joint cultures for 14 days. This prevents false negative results from “slower growers” which include Actinomyces species and Propionibacterium acnes. Holding of these cultures can be a burden for small microbiology labs. Methods A retrospective analysis of three years of joint cultures held for 14 days was reviewed. The length of time for the culture to turn positive and the organism that grew was noted. Results A total of 67 positive joint cultures were evaluated, which covered a period of 3 years at our institution. Of these, only 1 culture turned positive following day 5 (Propionibacterium acnes grew on day 6). The average time to positive for Propionibacterium acnes was 4 days. In comparison, the average growth time for Staphylococcus aureus and Proteus was 1 day, Pseudomonas aeruginosa was 1.2 days, all Streptococcus species was 2.4 days and Staphylococcus epidermidis was 2.7 days. No cultures grew Actinomyces during our study. Conclusion The consequences of missing a positive culture can be grave. In general, culture media has improved and provided increased growth rates. With resources becoming more limited, it may be time to revisit guidelines. This study is too small to be conclusive; a larger study may provide confirmation of the findings.