A technical report from the Italian SARS-CoV-2 outbreak. Postmortem sampling and autopsy investigation in cases of suspected or probable COVID-19

SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is a coronavirus responsible for COVID-19 (coronavirus disease 2019) which resulted in a cluster of cases of pneumonia that originated in China around 31 December 2019 and has subsequently spread across the globe. Currently, COVID-19 represents a health emergency worldwide, leading, in severe cases, to pneumonia, severe acute respiratory syndrome, multiorgan dysfunction or failure, and death. In the context of limited scientific knowledge and evidence of SARS-CoV-2 infection, guidance is becoming increasingly necessary for pathologists who have to perform postmortem investigations on COVID-19 cases. The aim of the present report is to share a procedure applicable to cases of COVID-19-related death, particularly in cases of death without medical intervention and in the absence of an ascertained SARS-CoV-2 infection and/or COVID-19 diagnosis, therefore providing support for diagnostic activity in the present COVID-19 pandemic. For this purpose, a standard operating procedure for correct swab collection, autopsy investigation and tissue sampling is provided.

[Genital herpes and pregnancy: Serological and molecular diagnostic tools. Guidelines for clinical practice from the French College of Gynecologists and Obstetricians (CNGOF)]

OBJECTIVES

To describe serological and molecular tools available for genital and neonatal herpes, and their use in different clinical situations.

METHODS

Bibliographic investigations from MedLine database and consultation of international clinical practice guidelines.

RESULTS

Virological confirmation of genital herpes during pregnancy or neonatal herpes must rely on PCR (Professional consensus). HSV type-specific serology (IgG) will allow determining the immune status of a patient (in the absence of clinical lesions). However, there is currently no evidence to justify universal HSV serological testing during pregnancy (Professional consensus). In case of genital lesions in a pregnant woman that do not report any genital herpes before, it is recommended to perform a virological confirmation by PCR and HSV type-specific IgG in order to distinguish a true primary infection, a non-primary infection associated with first genital manifestation, from a recurrence (Grade C). HSV IgM is useless for diagnosis of genital herpes (Grade C). If a pregnant woman has personal history of genital herpes but no lesions, whatever the gestational age, it is not recommended to perform genital sampling nor serology (Professional consensus). In case of recurrence, if the lesion is characteristic of herpes, virological confirmation is not necessary (Professional Agreement). However, if the lesion is not characteristic, virological confirmation by PCR should be performed (Professional consensus). At birth, HSV PCR samples should be collected as soon as neonatal herpes is suspected (symptomatic neonate) (best before beginning antiviral treatment but must not delay the treatment), or after 24hours of life in case of asymptomatic neonate born to a mother with herpes lesions at delivery (Professional consensus). Clinical samples for virological confirmation should include at least blood and a peripheral location. In case of clinical manifestations of herpes in the neonate, first samples PCR positive, preterm birth, or maternal primary infection or non-primary infection associated with first genital manifestation at delivery, CSF should also be collected as well as samples of lesions in the neonate if present (Professional consensus). Sampling should be repeated in case of PCR negative but strong evidence of neonatal herpes (Professional consensus). HSV serology is useless for diagnosis of neonatal herpes (Grade C).

CONCLUSIONS

Virological confirmation for diagnosis of genital herpes during pregnancy or neonatal herpes must rely on PCR. PCR assays available in France are very reliable. Specific IgG are dedicated to restricted indications.

Study and interest of cellular load in respiratory samples for the optimization of molecular virological diagnosis in clinical practice

BACKGROUND

Respiratory viral diagnosis of upper respiratory tract infections has largely developed through multiplex molecular techniques. Although the sensitivity of different types of upper respiratory tract samples seems to be correlated to the number of sampled cells, this link remains largely unexplored.

METHODS

Our study included 800 upper respiratory tract specimens of which 400 negative and 400 positive for viral detection in multiplex PCR. All samples were selected and matched for age in these 2 groups. For the positive group, samples were selected for the detected viral species.

RESULTS

Among the factors influencing the cellularity were the type of sample (p < 0.0001); patient age (p < 0.001); viral positive or negative nature of the sample (p = 0.002); and, for the positive samples, the number of viral targets detected (0.004 < p < 0.049) and viral species.

CONCLUSION

The cellular load of upper respiratory samples is multifactorial and occurs for many in the sensitivity of molecular detection. However it was not possible to determine a minimum cellularity threshold allowing molecular viral detection. The differences according to the type of virus remain to be studied on a larger scale.

[Microbiological diagnosis of viral respiratory infections in the adult patient]

Las técnicas tradicionales para el diagnóstico de los virus respiratorios siguen estando todavía vigentes, aunque los métodos moleculares aplicados al diagnóstico de la infección viral respiratoria han supuesto una auténtica revolución. Las técnicas moleculares tienen como principales ventajas una excelente sensibilidad, especificidad, capacidad de adaptación a virus emergentes, capacidad para detectar múltiples dianas en un mismo ensayo y posibilidad de automatización. Adicionalmente, estas técnicas han permitido profundizar en el papel de los virus en la infección respiratoria aguda a la vez que han descrito la existencia de nuevos virus no conocidos previamente. Los métodos moleculares y no moleculares de diagnóstico rápido para 1 o más virus respiratorios han permitido la toma de decisiones de forma inmediata en el manejo del paciente mejorando su pronóstico y evitando la transmisión nosocomial. Sin embargo, también hay inconvenientes, la mayor sensibilidad de las técnicas moleculares ha supuesto un incremento significativo de la tasa de codetecciones múltiples de virus respiratorios, cuya implicación clínica resulta difícil de interpretar. Finalmente queda por demostrar todavía si la utilización de las nuevas técnicas, de elevado coste, en el diagnóstico microbiológico de rutina de las infecciones respiratorias agudas de etiología viral, en el paciente hospitalizado, es coste-efectiva.

Rapid and generic identification of influenza A and other respiratory viruses with mass spectrometry

The rapid identification of existing and emerging respiratory viruses is crucial in combating outbreaks and epidemics. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid and reliable identification method in bacterial diagnostics, but has not been used in virological diagnostics. Mass spectrometry systems have been investigated for the identification of respiratory viruses. However, sample preparation methods were laborious and time-consuming. In this study, a reliable and rapid sample preparation method was developed allowing identification of cultured respiratory viruses. Tenfold serial dilutions of ten cultures influenza A strains, mixed samples of influenza A virus with human metapneumovirus or respiratory syncytial virus, and reconstituted clinical samples were treated with the developed sample preparation method. Subsequently, peptides were subjected to MALDI-TOF MS and liquid chromatography tandem mass spectrometry (LC-MS/MS). The influenza A strains were identified to the subtype level within 3h with MALDI-TOF MS and 6h with LC-MS/MS, excluding the culturing time. The sensitivity of LC-MS/MS was higher compared to MALDI-TOF MS. In addition, LC-MS/MS was able to discriminate between two viruses in mixed samples and was able to identify virus from reconstituted clinical samples. The development of an improved and rapid sample preparation method allowed generic and rapid identification of cultured respiratory viruses by mass spectrometry.

[Microbiological diagnosis of emerging arboviral and rodent borne diseases]

Vector borne viruses (VBV) include viruses transmitted by arthropods, rodents and other animals. In Spain the three main autochthonous VBVs causing human diseases are: Toscana, West Nile and Lymphocytic Choriomeningitis viruses. There are also other imported viruses that are potential threats to our public health, due to the presence of competent transmission vectors (dengue and chikungunya viruses in areas infested with Aedes albopictus), or due to the potential person-to-person transmission (Lassa and other viruses causing haemorrhagic fever). The Spanish Society for Infectious Diseases and Clinical Microbiology has responded to the emergence of VBVs by publishing a special issue of Microbiological Proceedings focused on the diagnosis of those emerging vector borne viruses of major concern in our country.

[Respiratory viruses: old and new. Review of diagnostic methods]

Acute respiratory infections (ARI) of viral origin are one of the main causes of morbidity and mortality worldwide. In addition to traditional viruses, such as the influenza virus, respiratory syncytial virus, rhinovirus, parainfluenza viruses 1 to 4, and adenovirus, other viruses such as metapneumovirus, new coronaviruses (human coronavirus NL63 and HKU1 and severe acute respiratory syndrome [SARS]-coronavirus), and recently bocaviruses, have been identified as causal agents of ARI. Although most of these viral infections follow a benign and selflimiting course in healthy adults, the consequences for the health care systems increase when they involve children, the elderly, immunosuppressed individuals, or those with chronic underlying diseases. These viral infections are an important cause of hospitalization and death, mainly during the cold months of the year, and, from a social-health perspective, ARI are a drain on economic resources and a frequent cause of work absenteeism. Occasionally, some of these viruses may cause emergent world health problems, as has occurred with the influenza virus pandemic strain and SARScoronavirus. While classical diagnostic methods based on culture and antigen detection remain useful for traditional respiratory viruses, recently described viruses are diagnosed mainly by molecular amplification techniques.