Answer
Andrea's staph infection persists after following her course of antibiotics because the strain of Staphylococcus aureus bacteria which is causing the infection has developed resistance to antibiotics. The prescribed treatment is thus taking no effect, which has allowed the infection to become worse.
Work Step by Step
1. Many infectious diseases which we deal with presently are the result of bacterial strains which have developed antibiotic resistance.
2. Such resistance is the consequence of antibiotic overuse. The large amount of exposure to antibiotics has allowed some bacterial strains to develop mutations which counteract the effectiveness of these antibiotics.
3. Staphylococcus aureus is a prevalent bacteria which causes staph infections and has strains that are resistant to penicillin, methicillin, and vancomycin.
4. The resistance which staph infections have to antibiotics is borne out by Andrea's example. Despite adhering to her course of antibiotics, no improvement is shown.
5. Indeed, the antibiotic treatment Andrea takes is so ineffective that after 3 days her lesion swells and yellow pus drains from it. In addition, Andrea also becomes feverish, compelling her mother to urge Andrea to follow up with her doctor.
