title: Effect of agitation of BACTEC 13A blood cultures on recovery of Mycobacterium avium complex.
abstract: The effect of agitation of BACTEC 13A bottles (Becton Dickinson) on the recovery of Mycobacterium avium complex (MAC) from blood was compared with that of static incubation. A total of 265 blood specimens was inoculated in duplicate into BACTEC 13A bottles. One specimen was statically incubated at 35 degrees C, and the other was incubated with agitation on a Gyrotory shaker at 35 degrees C for the first 2 weeks and thereafter without shaking for up to 12 weeks. Of the 265 specimens, 77 (29.1%) were positive in either one or both of the paired bottles. The average detection times for the shaken and nonshaken bottles were 12.7 and 15.9 days, respectively. A total of 10.4% of the specimens in the shaken bottles became positive 1 week before those in the nonshaken bottles, and 16.9% of the shaken cultures were positive more than 2 weeks before their counterparts. A further 46.8% of the agitated specimens became positive while the corresponding nonagitated cultures remained negative. When both specimens became positive at the same time, 88% of the shaken cultures had higher growth indices than their nonshaken counterparts. A further 11 paired blood cultures were taken from patients known to be infected with MAC to assess the effect of agitation of bottles on the utility of making twice-weekly readings during the first 2 weeks of incubation. Ten of the 11 sets of specimens in the shaken bottles were positive 1 or more weeks before those in the corresponding nonshaken bottles. In the remaining set, both specimens became positive on the same day; however, the growth index of the agitated culture was higher.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Mycobacterium Reference Laboratory, Fairfield Infectious Diseases Hospital, Victoria, Australia.
authors.forename: K
authors.initials: K
authors.lastname: Jackson
authors.forename: A
authors.initials: A
authors.lastname: Sievers
authors.forename: B
authors.initials: B
authors.lastname: Dwyer
mesh_terms: D016470:Bacteremia / Q000175:diagnosis; D001431:Bacteriological Techniques; D001769:Blood / Q000382:microbiology*; D006801:Humans; D015269:Mycobacterium avium Complex / Q000254:growth & development / Q000302:isolation & purification*; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis; D013997:Time Factors