Emphysematous cystitis is a rare form of complicated urinary tract infection characterized by gas inside the bladder and in the bladder wall. While the exact mechanisms underlying gas formation are not clear, gas-producing pathogens are clearly implicated in severe infection. E coli and Klebsiella pneumoniae are the most common organisms associated with emphysematous cystitis; others include Proteus mirabilis, and Enterobacter and Streptococcus species.
Abusnina W, Shehata M, Nassri S, Zeid F. Emphysematous cystitis. Cleve Clin J Med. 2019;86(1):10-11. doi: 10.3949/ccjm.86a.18063.