Images of Memorable Cases: Case 5 5. Cystitis emphysematosa Air in the wall and lumen of the urinary bladder. Gas-forming bladder infections typically occur in diabetic patients, and coliform bacteria are the usual pathogens. Urine from this patient, a diabetic, grew Escherichia coli. Other organisms, however, such as clostridia, staphylococci, and Nocardia and Candida species, are sometimes responsible.