Avery Koonce, 19, of Tyler, Texas, died Sept. 4 as the result of “paeniclostridium sordelli sepsis complicating parainfluenza laryngotraceobronchitis,” according to an autopsy report from the El Paso County Coroner’s Office. “In essence she died of untreated pneumonia,” said famed forensic pathologist Dr. Michael Baden, who reviewed the autopsy report obtained by The Post. The coroner described paeniclostridium sordelli as a “relatively rare but potentially fatal anaerobic bacteria” that is “associated with a toxic shock-like syndrome that can rapidly progress to death.” But it was “secondary” to the parainfluenza — or viral lung infection — the coroner’s report found. ......