Case of coexisting Nocardia cyriacigeorgica and Aspergillus fumigatus lung infection with metastatic disease of the central nervous system.

Nocardiosis is a rare opportunistic gram-positive bacterial infection. The genus Nocardia consists of non-motile, aerobic, non-spore-forming, catalase-positive, filamentous-branching bacteria with fragmentation into coccoid or bacillary forms. Opportunistic infections due to Nocardia are reported in immunocompromised patients. Aspergillus fumigatus is a conidia forming fungus that can be found in soil, plant matter and dust, causing invasive pulmonary and disseminated infection in immunocompromised patients. Both Nocardia cyriacigeorgica and A. fumigatus are known to cause pulmonary infection with metastatic dissemination to the central nervous system. We present a case of Nocardia and Aspergillus co-infection in a patient who presented within a few days of initiation of immunosuppressants for suspected systemic lupus erythematosus.

The effect of empiric antimicrobial treatment duration on detection of bacterial DNA in sterile surgical specimens.

Initial antimicrobial treatment of patients with deep seated or invasive infections is typically empiric. Usually, cultures of specimens obtained from the suspected source of infection are performed to identify pathogens and guide continued antimicrobial treatment. When patients present with signs and symptoms of infection, but sterile body fluid or tissue specimens cannot be obtained in a timely fashion, growth of bacterial pathogens in culture may be inhibited following initiation of empiric antibiotic treatment. To address this clinical dilemma, we performed a prospective evaluation of conventional culture vs. PCR coupled to electrospray ionization mass spectrometry (PCR/ESI-MS) on sterile body fluids and tissues submitted to the diagnostic microbiology lab following initiation of empiric antibiotic treatment for patients with suspected infection. In this series of surgical samples, PCR/ESI-MS identified bacterial pathogen(s) in 56% (49/87) of patients with non-diagnostic cultures. Examination of patients stratified by antibiotic treatment duration demonstrated that PCR/ESI-MS sustains high rates of bacterial DNA detection over time by generalized estimating equation models (p<0.0001).