Yet, none of these tests have high specificity and are to be interpreted in the setting of other relevant clinical information. for 15% of AIDS-related deaths . Other forms of fungal meningitis are rarer, but also deadly. Antinori reported a case fatality rate of 63.5% due Rabbit polyclonal to RAB14 to meningitis for immunocompetent and 83% for immunocompromised patients . Meningitis cause by has mortality of 90% at 1?year and 100% at 2?years if untreated . CNS infections due to have a 39% case fatality rate . It is not always possible to determine the etiology of meningitis. A study by Sulaiman only identified the etiology in about 32% of cases, while other studies found similar ranges [16C18]. This is likely related to the lack of sensitivity of CSF cultures for non-bacterial pathogens as well as the underutilization of viral molecular and serologic testing . Of course the etiology in any individual case may be influenced by many factors including test availability, geographic region, host, and many others C the main point is that the exact etiology is not always uncovered. Due to the high mortality and morbidity of many types of meningitis, it is critical to obtain a diagnosis or initiate empiric treatment rapidly as soon as possible . S38093 HCl Clinician diagnoses must be informed by historical information such as duration of symptoms, travel and country of origin, host immune capabilities, vaccination status, as well as an understanding of the appropriate diagnostic testing based on the probable epidemiology . This review will focus on the diagnosis of bacterial, mycobacterial, fungal meningitis due to their worse prognosis and need for accurate diagnosis as well as the various diagnostic tests used in these conditions. Given viral meningitis typically is generally associated with relatively good outcomes, PCR testing of viral etiologies will not be a major focus of this review. This is an extensive narrative review. We searched pubmed for meningitis and diagnosis, epidemiology and meningitis, risk factors and meningitis, stem cell transplant and meningitis, organ transplant and meningitis, bacterial meningitis, tuberculosis meningitis, fungal meningitis, histoplasma meningitis, coccidioides meningitis, cryptococcal meningitis, blastomyces meningitis and meningitis to gather data in addition to using material cited in some of the sources found via these searches. Epidemiology Although an estimated 16?million cases of bacterial meningitis occurred worldwide in 2013, S38093 HCl only 4100 cases per year occur in the USA [2,19]. In Western countries the incidence of bacterial meningitis over the past 10C20?years has declined by approximately 3C4% per year and currently is approximately 0.8 cases per 100,000?per year . The rates of bacterial meningitis are significantly higher in many African countries with an incidence of 10C40?per 100,000 persons per year . The most common etiologies in order of frequency are [4,20]. Meningitis due to type B and has decreased over the past 10C20?years, due to vaccination [3,20,21]. Aseptic meningitis is relatively common with an annual incidence of 7.6?per 100,000 adults in the USA . Enteroviruses, herpes simplex virus, varicella zoster virus and West Nile virus are the most common causes of infectious aseptic meningitis, other causes include cytomegalovirus and human immunodeficiency virus (HIV), among others [18,22,23]. Aseptic meningitis can also be caused by non-infectious etiologies such as adverse reaction to medications, chemotherapy, vaccinations or inflammatory diseases [22,23]. In 30C65% of cases of aseptic meningitis, the etiology is not definitively identified . Tuberculosis (TB) meningitis incidence is not known, but likely occurs in about 1C5% of TB cases worldwide . In 2017 WHO estimated S38093 HCl 10?million incident cases of tuberculosis, which would correlate to 100,000C500,000 cases per year of TB meningitis . Worldwide, fungal meningitis causes substantial mortality, particularly among immunocompromised persons . The primary pathogens implicated are estimated 223,100 incident cases of cryptococcal meningitis with 181,100 annual fatalities . Sub-Saharan Africa accounted for 73% of the 223,1000 cases . Meningitis due to is most commonly seen in immunocompromised individuals, especially those with HIV [5,26]. However in high-income countries, 30% of cryptococcal meningitis occurs in apparently immunocompetent individuals, particularly if due to . Meningitis due to typically occurs as a results of dissemination and so is relatively uncommon in hosts with intact immune systems. Meningeal involvement occurs in 33C50% of disseminated coccidioidomycosis and 10C20% of disseminated histoplasmosis . Regional variation in frequency and etiology of meningitis occurs as well. For instance, the meningitis.