Acute bacterial prostatitis is caused by:: (A) E. Coli, (B) Streptococcus viridans, (C) Staphylococcus aureus, (D) Proteus
Answer is A. Ref. Textbook of Microbiology and Immunology BY Parija. Page. 182, 261
 
Bacterial prostatitis is usually caused by E. coli or another gram-negative rod, with one of two presentations.

Acute bacterial prostatitis presents with fever and chills; prostate examination should be gentle or not performed at all, as massage may result in a wave of bacteremia.
Chronic bacterial prostatitis presents as recurrent episodes of bacterial cystitis