Routine Testing for Anaerobic Bacteria in Cerebrospinal Fluid Cultures Improves Recovery of Clinically Significant Pathogens

Abstract

cIn North America, the widespread use of vaccines targeting Haemophilus influenzae type b and Streptococcus pneumoniae have dramatically altered the epidemiology of bacterial meningitis, while the methodology for culturing cerebrospinal fluid (CSF) specimens has remained largely unchanged. The aims of this study were 2-fold: to document the current epidemiology of bacterial meningitis at a tertiary care medical center and to assess the clinical utility of routinely querying for anaerobes in CSF cultures. To that end, we assessed CSF cultures submitted over a 2-year period. A brucella blood agar (BBA) plate, incubated anaerobically for 5 days, was included in the culture procedure for all CSF specimens during the second year of evaluation. In the preand postimplementation years, 2,353 and 2,302 CSF specimens were cultured, with 49 and 99 patients having positive culture results, respectively. The clinical and laboratory data for patients with positive cultures were reviewed. Anaerobic bacteria were isolated in the CSF samples from 33 patients post-BBA compared to two patients pre-BBA (P ‫؍‬ 0.01). The anaerobic isolates included Bacteroides thetaiotaomicron (n ‫؍‬ 1), Propionibacterium species (n ‫؍‬ 15), and Propionibacterium acnes (n ‫؍‬ 19) isolates; all of these isolates were recovered on the BBA. Eight of the 35 patients from whom anaerobic organisms were isolated received antimicrobial therapy. Although six of these patients had central nervous system hardware, two patients did not have a history of a neurosurgical procedure and had community-acquired anaerobic bacterial meningitis. This study demonstrates that the simple addition of an anaerobically incubated BBA to the culture of CSF specimens enhances the recovery of clinically significant anaerobic pathogens.

Diagnostic Approach to Health Care- and Device-Associated Central Nervous System Infections

“…Prior antibiotic treatment is a common cause of falsely negative CSF Gram stain and culture, with up to 50% of patients having received antibiotics before CSF collection in some studies (21). Interlaboratory differences in the set up and processing of devicecollected CSF samples are another major cause of variable culture yield and performance across institutions (13,33,(42)(43)(44)(45). The recommendations regarding the need for CSF centrifugation prior to culture, anaerobic culture, anaerobic transport media, broth culture, duration of broth incubation, and the role, appropriateness, and procedure for CNS device tip cultures are frequently not explicit and differ between standard clinical microbiology references (44,45).…”

“…Several studies have reported an increase in the proportion of positive CSF cultures and clinically significant Propionibacterium spp. infections with the addition of anaerobic culture (solid media or broth) and prolonged incubation of broth media (10 to 14 days) (13,30,42,46). Calderaro et al observed a shorter time-to-positivity and a 79% increase in the detection of aerobic bacteria and yeast with an inoculation of 1 to 3 ml CSF into a Bactec Peds Plus/F blood culture bottle over that with conventional agar culture (43).…”

“…The wide variation in the observed rate of infection is most likely due to differences in EVD utilization and handling at individual facilities and variation in how VAI is defined across studies. Differences in microbiologic culture procedures also contribute to differences in the rate of VAI between institutions (13).…”

High‐throughput sequencing of cerebrospinal fluid for diagnosis of chronic Propionibacterium acnes meningitis in an allogeneic stem cell transplant recipient

“…P. acnes is a part of the normal flora of the skin and may be associated with biofilms . It is well recognized as a cause of CNS infections in patients with a CSF shunt or other foreign material present , but is often dismissed as a contaminant when it is recovered from CSF cultures from patients who do not have foreign material present.…”

“…Bacterial, mycobacterial, and fungal cultures were performed. The process used for CSF culture in the treating institution included centrifugation of the CSF specimen with inoculation of the sediment on sheep blood agar and chocolate agar (Remel, Lenexa, Kansas USA) incubated in 5% CO 2 for a minimum of 48 h, plus an anaerobic culture consisting of inoculation of sediment onto a pre‐reduced Brucella blood agar plate, which was incubated anaerobically for a total of 5 days . All cultures from his CSF were negative, as were PCR assays of CSF for herpes simplex virus (HSV), cytomegalovirus, human herpesvirus‐6, varicella zoster virus, and Toxoplasma gondii .…”