Brain Abscess in the Twenty-First Century: the Importance of Timing of Pus Sampling To

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Brain abscess in the twenty-first century: the importance of timing of pus sampling to. the likelihood of obtaining positive culture results Dr James Melhorn1 & Professor Philip Kane2, 1Cambridge University Hospitals NHS Foundation Trust, Cambridge & 2South Tees Hospitals Foundation Trust, Middlesborough

Introduction Results Figure 3. Causative organisms identified from brain Discussion Brain abscess is rare, with an incidence of Median age of the cohort was 54.6 years with a abscess pus samples (30) plus a further 6 cultures Although Otitis media (OM) is the most common approximately 0.3 to 1.3 cases per 100,000 male to female ratio of 1.7:1. A majority of 84.9% of from infective sources believed to be causative for identified causal infection for our cohort we note a the respective brain abscesses people per year. In Europe, it is almost cases were supra-tentorial single abscesses with decline in the relative contribution of OM to brain always secondary to a focus of suppuration 11.3% infra-tentorial single abscesses and 3.8% abscess in the context of previously reported UK somewhere else in the body. cases of multiple abscesses. Mortality at one year cohorts. This could reflect a reduced burden of specific to brain abscess was 9.4%, while mortality middle ear disease. We also note that while rare, It has been suggested that delayed for brain abscess and its primary causes was 16%. the contribution of gram negative bacteria and identification of pathogens in a brain abscess Forty-seven of 53 patients underwent neurosurgery fungal pathogens may be increasing in response to can result in harm to the patient in the form of with 25 patients having two surgeries and 5 new states of immuno-compromise and increased irreversible focal neurological deficits, patients undergoing three surgeries. A total of 57 neurosurgery epilepsy and loss of mental acuity. The aspirated pus samples submitted for culture from European (GISIG) working group on brain 38 of the 53 patients in our series were eligible for Our data, as demonstrated in Figure 2, shows a abscesses recommend (5.4.1) that a ‘sample analysis. Patients were treated with multiple clear association between the likelihood of from the abscess should be made without antibiotic regimes: the most common being obtaining a positive bacterial culture from a brain antibiotic therapy or at least within not more Ceftriaxone ± Metronidazole ± Rifampicin abscess and the duration of intravenous antibiotics than 3 days of the start of therapy.’1 The a patient has received when the sample is taken. practical issue of how long a successful Figure 2. Positive versus negative bacterial culture results This is further supported by consideration of the culture can be obtained after IV antibiotics from pus samples obtained from brain abscesses, per exceptions. The only sample that had been taken are commenced has a very limited evidence duration of intravenous antibiotic therapy (hours). All 4 of our patients with fungal growths within the first 48 hours of IV antibiotics that failed base, however. It is a pertinent issue as brain Probability of obtaining a positive versus negative culture (Aspergillus, Saccharomyces, Candida x2) to culture a pathogen was taken from a multi- abscess patients often require stabilization at pre and post 24, 48, 72 hours were all significant (p < 0.001) using Fishers Exact Test. died within a year of diagnosis. None of our loculated abscess (and a positive culture was prior to surgery; and surgery should be cohort had HIV. obtained on a second aspiration). Of the two cases performed within regular working hours 25 Growth No Growth that cultured a pathogen after >5 days of IV wherever possible. Ten patients were initially treated as brain therapy, one was the notoriously resilient nocardia.

20 tumour before either rapid growth of the Our findings are also supported by Janssen et al Methods (2004)2, who found a significant difference in the space occupying lesion or pus obtained at We describe a cohort of 53 cases of intra- probability of obtaining a positive culture between biopsy disclosed the diagnosis parenchymal brain abscess referred to 15 aspirates taken before and after 72 hours of IV James Cook University Hospital, antimicrobial chemotherapy. Middlesbrough between 2000 and 2013. Table 1 Pathogenesis of brain abscess by groups. aspirationsof 10 ‡ denotes 2 cases and † denotes 1 case The concept of a 48 or 72 hour window in which to associated with immuno-compromise Figure 1. Brain abscess in a 61 y.o lady secondary perform a diagnostic aspiration is suggestive from to a right-left shunt. The chest radiograph shows an Number Number 5 the very limited observational data. Confounding arterio-venous malformation in the right mid zone. Pathogenesis Number of Cases issues such as patient fitness for surgery and the The saggital MR slice shows the right parieto- Cryptogenic‡ 14 eloquence of surrounding brain tissue in decisions occipital abscess 0 Otitis Media & Sinusitis 11 < 24 24-48 48-72 72-96 96-120 > 5 days to aspirate must be acknowledged. Time from start of IV Antibiotic therapy IVDU 5 Lung Abscess‡ 5 References Only 4 patients presented with the classic brain Right to Left Shunt 5 1Arlotti M, Grossi P & Pea F (2010) Consensus document on controversial Post Neurosurgery 4 abscess triad of fever, headache and focal issues for the treatment of infections of the central nervous system: Odontological 3 bacterial brain abscesses, International Journal of Infectious Diseases, 14, neurological deficit. Symptoms were more likely Endocarditis 2 S4, S79-S92 2Jannsson A K, Enblad P, & Sjölin J (2004) Efficacy and Safety of non-specific such as headache (63.5%), nausea & Direct Contiguous Spread 2 Cefotaxime in Combination with Metronidazole for Empirical Treatment of vomiting (34.6%) and malaise. Seizures, either Urosepsis 1 Brain Abscess in Clinical Practice: A Retrospective Study of 66 partial or generalized, affected 25% of our cohort. Oesophageal Dilatation† 1 Consecutive Cases, European Journal of Clinical Microbiology and Infectious Diseases, 23, 7-14