Staph infections, caused by the bacterium staphylococcus aureus, are increasing in frequency and are more difficult to treat with antibiotics. many staph infections are now caused by mrsa, and methicillin-resistant strain of s. aureus. what explains the more widespread phenomenon of mrsa prevalence in staph infections? a) vaccines for mrsa have become not effective because of changes to human immune systems. b) the presence of antibiotics induced the bacterial genomes to mutate and develop resistance to the drug. c) decreased hospital sanitation practices to save money have resulted in increased presence of resistant staph infections. d) selective pressures by excessive antibiotic use have increased the frequency of resistant strains of s. aureus over the last few decades.

Mr. j, age 42, is a construction worker in las vegas. he recently noticed that a mole on his face seemed to be getting larger and darker. at first he did not worry because he was in the sun a lot and assumed the change may have been caused by sunburn. after a month, not only was the mole larger and darker, but it appeared to be “bumpy.” his doctor diagnosed a malignant melanoma skin cancer following biopsy of the nevus. mr. j reports pain in his right shin that does not go away when he puts his feet up or sleeps. discussion questions 1. relate mr. j’s skin changes to the warning signs for malignant melanoma. (see malignant melanoma.) 2. discuss the normal progression of this malignancy. what is the significance of the bone pain that mr. j is experiencing? (see malignant melanoma.) 3. discuss the treatment available for this patient and the prognosis for recovery. (see malignant melanoma.)