Most of the main pathogens of acute respiratory infections are seen in viral infections, which are responsible for roughly 70% of clinical statistics. The viruses include respiratory syncytial virus, coronavirus, influenza virus, parainfluenza virus, rhinovirus, adenovirus, and coxsackievirus. The other 30% are caused by bacterial infections, either secondary to viral infections in acute upper respiratory tract infections or directly from bacterial infections. There are also other pathogens, such as Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella, Mycoplasma, Chlamydia, and others.