Older adults who are hospitalized for pneumonia are at high risk for heart problems. About 20 percent of patients experience complications such as congestive heart failure or cardiac arrhythmia, which have been implicated in more than a quarter of pneumonia-related deaths. Along with the low oxygen levels caused by a lung infection, stress on heart muscles may be a direct result of invading bacteria, according to a study published today (September 18) in PLOS Pathogens. Researchers from the University of Texas Health Science Center at San Antonio (UTHSCSA) and their colleagues found that mice and rhesus macaques infected with Streptococcus pneumoniae developed myocardial microlesions, which were also present in human autopsy samples.