Many respiratory pathogens are gram-positive bacteria.
Because gram-positive bacteria are very resistant to drying, they are easily transmitted in air. Less hardy respiratory pathogens can be transferred from person to person via respiratory aerosols generated by coughing, sneezing, talking, or breathing. Two respiratory diseases caused by streptococci are streptococcal sore throat and pneumococcal pneumonia. Under certain conditions, simple Streptococcus pyogenes infections can develop into more serious conditions such as scarlet fever or rheumatic fever. Pneumonia caused by Streptococcus pneumoniae is always a serious disease.