Comparison of PCR and culture for detection of Nocardia asteroides in brain specimens from experimentally infected BALB/c Mice

Abstract

Systemic infection of BALB/c mice with Nocardia asteroides strain GUH-2 results in widespread replication of the organism in the brain, followed by its immune-mediated clearance. The present study compared the sensitivity of polymerase chain reaction (PCR) to bacterial culture for detection of cerebral nocardial infection in this experimental system. Mice (n=4/time point) were administered N. asteroides by intravenous injection, and brain specimens were evaluated for Nocardia by PCR and culture at post-infection days 2, 7, 14 and 21. Nocardia was detected by PCR in all infected animals on post-infection days 2, 7, and 14, and in one of four mice on post-infection day 21; in contrast, the organism was detected by culture only on post-infection days 2 and 7. These findings suggest that PCR may be more sensitive than culture for the detection of low numbers of Nocardia in the brain.

An unusual murine behavior following infection with log-phase Nocardia asteroides type 6 strain GUH-2 (Nocardia cyriacigeorgica GUH-2)

“…The median number of days for the onset of impaired movements appeared to be 15 days after infection. There were no lesions observed in the mid-brain in any of these mice, but the organisms grew freely for the first 72 h [6,8,13] and then gradually disappeared such that by 15 days postinfection, no organisms could be cultured [11,13]. Although the brains were sterile at this point in time, the substantia nigra appeared to be the major (but not exclusive) target for damage by GUH-2 in headshake mice [6,8e 10,13].…”

Nocardia farcinica pericarditis after kidney transplantation despite prophylaxis

“…A previous English‐language literature review demonstrated 29 case reports of Nocardia bacteremia, only 2 of which were reported as N. farcinica (22). There have been experimental reports using polymerase chain reaction to expedite identification of Nocardia in addition to improving the sensitivity of the test when compared with culture alone, but this does not appear to be widely clinically available (23).…”

Treatment of cardiac nocardiosis in a post-renal transplant patient of systemic nocardiosis

“…PCR is a rapid and sensitive method for detection of Nocardia in blood and different visceral organs. 7 In comparison, Nocardia specie usually require 5-21 days for growth in routine aerobic culture. 8,9 Interestingly, TTE performed as a part of work up showed a mobile mass attached to the posterior leaflet of the mitral valve.…”