<prompt> The commonest pathogen responsible for acute pyelonephritis in pregnancy is:Escherichia coliKlebsiella pneumoniaeProteus mirabilisPseudomonas aeruginosa  <response>: E. coli is the common bacteria responsible for acute pyelonephritis in pregnancy It also causes asymptomatic bacteriuria. Urinary tract infection in pregnancy is a risk factor for threatened aboion, chorioamnionitis, preterm labor, IUGR. 