Relatively few obstetricians in high-income countries will experience the tragedy of a maternal death, and fewer still will see one result from meningitis. When such cases arise, the obstetricians will be partners in care alongside physicians and intensivists. It is more than half a century since a major review on meningitis in pregnancy has been published, and here BJOG presents a significant report and review of the condition.
Acute bacterial meningitis (ABM; that is, acute pyogenic, non-tuberculous-viral-fungal infection) still has a high mortality rate of >20% in adults, with rapid evolution and relatively non-specific presenting signs and symptoms. Antibiotic resistance is not an issue with the usual causative organisms. The problems lie in delayed diagnosis and the biology of the disease. The observational study on fatal meningitis (all causes) among pregnant women in the Netherlands published in this issue is significant for several reasons.1 Firstly, it is the first study of meningitis in pregnancy published in 50 years that is not a case report, or case series of between one and six cases,2 but instead represents all the known cases for a country over a period of 23 years (1983–2007). Fifteen of 489 maternal deaths (direct and indirect causes) were ABM or other meningoencephalitis. In fact, all of the meningitis cases happened in the last 15 years, when 344 mothers died, making meningitis the cause of 4.4% of maternal deaths. From admittedly small numbers, the case fatality rate could be as high as 38%. Secondly, the rate of pregnancy-associated ABM in the Netherlands appears to be higher than that in the only other European country (the UK) that publishes similar audits of all known maternal deaths. The incidence of meningitis in the Netherlands for 1993–2007 was 0.5/100 000 live births; the overall maternal mortality rate (MMR) was 11.8/100 000 live births. Excluding the three non-ABM cases, the Netherlands ABM rate was actually 0.4. In the UK, with a similar overall MMR, the ABM fatality rate in 2006–2008 was 0.13, and the highest recorded rate in any triennium was only 0.24.1,3 Why the difference between countries with similar socio-economic conditions? Thirdly, the organisms and chronologies are documented. Ten (67%) deaths were caused by Streptococcus pneumoniae (pneumococcus), and there were single cases of Streptococcus milleri, Haemophilus influenzae, Mycobacterium tuberculosis, Cryptococcus neoformans and herpes simplex meningoencephalitis. All the streptococcal and the herpes simplex virus (HSV) infections were diagnosed before delivery (15–37 weeks of gestation; median 34 weeks of gestation); the cryptococcal, tuberculous and H. influenzae patients presented 10–27 days postpartum. Only one woman had an HIV infection and was receiving antiretroviral therapy, and she developed pneumococcal infection. The pattern and chronology of the infections raise questions over the susceptibility to infection in pregnancy. Fourthly, the clinical features, diagnostic processes, treatments and possible risk factors for fatal meningitis are documented. Nearly all (87%) presented with headache, most had altered mental status and fever, but only five had documented neck stiffness. The microbiological diagnoses were based on cultures of cerebrospinal fluid (CSF) and blood; only one patient was autopsied. All but one patient received antibiotics before death: the cryptococcal patient appears to have presented with postpartum psychosis, and was diagnosed post-mortem. Regarding risk factors for infection, no patient had spinal anaesthesia or cranial operative interventions. But nine of 15 patients had clinical and/or radiological evidence of otitis infection prior to meningitis. In fact, excluding the patients with HSV, tuberculosis and cryptococcosis, where ear infection would not be relevant pathogenetically, nine of 12 (75%) women had preceding ear infection. This raises questions over the management of otitis in pregnancy.
Obviously, such a retrospective study has limitations, which are acknowledged. All pregnancy-associated meningitis deaths may not be reported to the Dutch Maternal Mortality Committee (MMC), particularly if they are postpartum. The absence of reported cases from 1983 to 1993 suggests that under-reporting must happen alongside, presumably, improved diagnostic methods over time. Some clinical data are always missing in national studies such as this, perhaps including more HIV-positive women. There are no denominator data on women, pregnant or not, with meningitis who did not die. This is a standard problem with all medical confidential enquiries that are based on analysing deaths. These facts are also common to the Confidential Enquiries into Maternal Deaths in the UK. Nonetheless, we can ask why pneumococcus infection appears to be so important in pregnancy-associated meningitis, why ear infection appears to be an important predisposing factor and whether this explains the differences in data from Netherlands and the UK?