We randomly allocated infants to receive injectable procaine benzylpenicillin-gentamicin for 7 days ( group A , reference group ) ; injectable gentamicin and oral amoxicillin for 7 days ( group B ) ; injectable procaine benzylpenicillin-gentamicin for 2 days , then oral amoxicillin for 5 days ( group C ) ; or injectable gentamicin for 2 days and oral amoxicillin for 7 days ( group D ) .