Microbial co-infections and pathogenic consortium with SARS-CoV-2 in
COVID-19 patients: A contingent review
Abstract
The emergence of novel coronavirus infectious disease-2019 (COVID-19) in
December 2019, caused by severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2) has traumatized the whole world with the ongoing
devastating pandemic. After droplet mediated transmission of infectious
virus particle, and subsequent tissue tropism through the upper and
lower respiratory tract, the acute clinical disease is manifested by
severe respiratory illness accompanied by shortness of breath,
progressive pneumonia, multi-organ dysfunction and ultimate death in
SARS-CoV-2 infected patients. The involvement of other microbial
co-infections leading to extortionate ailment in critically ill patients
has not been significantly reviewed along with conclusive reporting on
underlying molecular mechanisms in COVID-19 patients. Although the
incidence of co-infections could be up to 94.2% in laboratory-confirmed
COVID-19 cases, the fate of co-infections among SARS-CoV-2 infected
hosts often depends on the balance between the host’s protective
immunity and immunopathology. The cross-talk between co-pathogens
(especially lung microbiomes), SARS-CoV-2 and host is an important
factor that ultimately increases the difficulty of diagnosis, treatment,
and prognosis of COVID-19, and even increase the symptoms and mortality
of the disease. Simultaneously, co-infecting microorganisms may use new
strategies to escape host defense mechanisms (by altering both innate
and adaptive immune responses) to further aggravate SARS-CoV-2
pathogenesis. This review of literature suggests that clinicians should
rule out SARS-CoV-2 infection by ruling in other respiratory
co-pathogens, and must have a high index of suspicion for co-infection
among COVID-19 patients. Thus, after recognizing the possible pathogens
causing co-infection among COVID-19 patients, and the underlying
molecular mechanisms of co-infections appropriate curative and
preventive interventions can be recommended.