Clinical Studies
Infectious cause of death determination using minimally invasive autopsies in developing countries

https://doi.org/10.1016/j.diagmicrobio.2015.10.002Get rights and content

Highlights

  • We describe a series of 30 minimally invasive autopsies (MIA) performed in Maputo, Mozambique.

  • Extensive microbiological investigations successfully identified the etiology of most fatal infections.

  • MIA samples and the developed protocol seem valid for infectious cause of death investigation.

Abstract

In developing countries, the knowledge of the microorganisms causing fatal infections is critical and could help designing and implementing more effective preventive interventions and treatment guidelines. We aimed to develop and validate protocols for microbiological analysis in post-mortem samples obtained during minimally invasive autopsy (MIA) procedures and to assess their performance. Thirty MIAs performed in adults at Maputo Central Hospital in Southern Mozambique were included in the analysis. Microbiological tests included a universal screening for HIV, hepatitis B and C viruses, Plasmodium falciparum, and bacterial/fungal culture. In addition, a variety of molecular microbiology assays guided by the histological results were performed in blood, cerebrospinal fluid and a variety of tissue samples including liver, lung and central nervous system. The combination of culture-based methods together with molecular microbiological assays led to the identification of 17 out of 19 (89.5%) of the infectious deaths. Microorganisms identified included Mycobacterium tuberculosis, Toxoplasma gondii, Pneumocystis jiroveci, Cryptococcus neoformans, hepatitis B virus, human herpesvirus 8, cytomegalovirus, Streptococcus pneumoniae, Streptococcus dysgalactiae, Ryzopus oryzae, and Acinetobacter baumannii. The combination of classical cultures, serological tests and molecular assays performed in samples obtained through MIA allows the identification of most infectious agents causing death.

Introduction

In developing countries mortality associated to infectious diseases remains unacceptably high (Sepúlveda and Murray, 2014). The knowledge of the microorganisms involved in the infectious diseases is critical in these settings, where a precise information on the principal etiologies would help the design and implementation of more effective preventive interventions such as vaccines and prophylactic schemes as well as improved treatment guidelines. However, available data on the etiology of fatal infections is scarce. Complete diagnostic autopsy (CDA) remains the gold standard for the investigation of the cause of death (CoD), and despite significant advances in clinical diagnosis, major clinico-pathological discrepancies are reported in up to a quarter of CDAs (Kuijpers et al., 2014). Interestingly, many of these clinicopathological discrepancies are related to infectious diseases (Battle et al., 1987, Sarode et al., 1993).

Minimally invasive autopsy (MIA) has been proposed as an alternative to CDA. Some studies show comparable results of the MIA protocols to those obtained by CDA, and often include biopsy of key organs guided by imaging equipment such as CT scan (Sebire et al., 2012, Thayyil et al., 2010, Weustink et al., 2009). Investigating cause of death using MIA protocols appears as a promising tool for developing countries, in areas where there is no capacity to perform CDA and where modern imaging techniques are not available. We aimed to develop a MIA protocol including organ-directed sampling with subsequent histological and microbiological analyses with special interest in infectious diseases. In this regard, postmortem microbiological analyses have not been widely used in developing countries, probably because of difficulties in implementing microbiological procedures in daily autopsy practice. The diagnosis of infectious diseases usually combines both classical microbiological-culture based techniques and modern molecular assays. A difficult interpretation of bacterial cultures is rather a rule than an exception in post-mortem microbiological analysis, unless stringent precautions are taken (Morris et al., 2006). Bacterial isolates from autopsy samples may correspond to true pathogens but may also reflect transient bacteremia (Seifert, 2009), contamination during sampling or post-mortem translocation of commensal flora (Caplan and KF 2001, Fernández-rodríguez et al., 2013, Morris et al., 2006, Prtak et al., 2010). It is generally accepted that post-mortem bacterial translocation does not have a significant impact if the samples are obtained within 24 hours after death and the corpse has been maintained refrigerated at 4 °C (Morris et al., 2006). Nevertheless, these conditions do not exclude external contamination during the sampling procedure. The above mentioned limitations, together with the lack of sensitivity for fastidious or labile microorganisms have accounted for the limited value of standard microbiological cultures in autopsy studies. Molecular microbiology methods, most of them based on polymerase chain reaction (PCR) assays, have generally higher sensitivity than culture based techniques and appear as an important tool for post mortem microbiological investigations.

The objective of this study was to develop and validate protocols for microbiological analysis in post-mortem samples obtained during MIA procedures and to assess their performance in a series of 30 cases.

Section snippets

Matherial and methods

An ongoing validation study for a simplified minimally invasive autopsy (MIA), in comparison to the CDA (CaDMIA project) (Bassat et al., 2013) is being carried at the Maputo Central Hospital (MCH), Mozambique. Extensive microbiological investigations were included to identify the infectious CoD (ICoD). The study protocol was approved by the National Mozambican Ethics Committee (ref. 342/CNBS/13) and the Ethics Committee of the Hospital Clinic in Barcelona (HCB). For all of them, a CDA had been

Etiological diagnosis of the infectious causes of death

The demographic characteristics of the patients, the histological diagnosis and the microbiological results are summarized in Table 1. Among the 30 cases included in this study, 14 (46.7%) were diagnosed by histology as having an ICoD, including 6 meningoencephalitis, 3 pyogenic pneumonia, 3 disseminated necrotizing granulomatosis, 1 pneumocystis pneumonia, and 1 cryptococcal septicemia. In addition, two additional ICoD were identified by the microbiological analysis: one Streptococcus

Discussion

Our results show that the combination of standard culture and molecular assays in samples collected through MIA procedures allows detection of an etiological agent in the great majority (89%) of the infectious deaths. Although the number of cases included is relatively small, these results suggest that the sampling and testing strategies used in this study are valid for the etiological diagnosis. Up to 11 different pathogens were identified among 17 deaths of infectious origin. This represents

Funding

The CaDMIA research project (Validation of the minimally invasive autopsy tool for cause of death investigation in developing countries) is funded by the Bill & Melinda Gates Foundation (Global Health grant number OPP1067522) and by Spain’s Instituto de Salud Carlos III (FIS, PI12/00757). QB has a fellowship from the program Miguel Servet of the ISCIII (Plan Nacional de I + D + I 2008–2011, grant number: CP11/00269).

Conflict of interest

None of the authors have any conflict of interest.

Acknowledgements

We would like to thank the families of all the deceased patients included in this study. The authors are grateful to all members of the Department of Pathology at the Maputo Central Hospital whose support made this study possible and also to the staff of the “Centro de Investigação em Saúde de Manhiça” for their logistic support. We specifically thank Mr. Bento Nhancale for his invaluable support to the study.

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