sentences:  He first became interested in the role of atypical bacterial forms after noting that a large number of patients with urinary tract infections suffer from continual relapsing illness.Using a direct phase microscope, he examined the urine specimens of several patients with urinary tract infections and found atypical bacteria in his samples.He began to investigate atypical bacteria (cell wall-defective, L-forms and difficult-to-culture bacteria) striving to better understand their biology and the role they play in causing disease.