Penicillin resistance in S. pneumoniae

• this is sometimes known as pneumococcus

• 45-yo man was admitted with high fever and painful, swollen right knee

• Gram stain was positive for diplococci; both blood and joint culture grew Streptococcus pneumoniae

• by day 3, the patient felt better overall but continued to have fever and the knee had not improved

• the patient had septic arthritis; bacteria entered bloodstream and localized itself to the joint

• the strain of S. pneumoniae was reported as having intermediate resistance to penicillin. the patient was switched to vancomycin and showed steady improvement

• this was due to acquisition of a new penicillin-binding protein less sensitive to penicillin, hence conferring penicillin resistance

• this can be acquired by transformation in vitro

Category: Microbiology Notes