50 - Antibiotics III Flashcards
Case Study 1
A 64-year-old woman with Type II diabetes presented with a foot infection. She recently underwent surgical debridement of the involved tissue and bone on her right foot. She has no known allergies. Examination of temperature, respiratory rate, heart rate, and pulse oximetry reading are all within normal ranges. Gram-stain of a sample collected during the debridement procedure is shown below.
Is this complicated or uncomplicated?
Complicated category
Based on the type of infection and Gram staining results, what is the most likely causative organism?
Staph aureus –> gram positive clusters
What is a reasonable therapeutic strategy for treatment?
Broad spectrum penicillin plus beta-lactamase inhibitor
If a resistant organism is identified, what agents would be effective?
Vancomycin, linezolid, daptomycin ***
Case study 2
A 55-year-old man is brought to the local hospital emergency department by ambulance. His wife reports that he had been in his normal state of health until 3 days ago when he developed a fever and a productive cough. During the last 24 hours he has complained of a headache and is increasingly confused. His wife reports that his medical history is significant only for hypertension, for which he takes hydrochlorothiazide and lisinopril, and that he is allergic to amoxicillin. She says that he developed a rash many years ago when prescribed amoxicillin for bronchitis. In the emergency department, the man is febrile (38.7°C [101.7°F]), hypotensive (90/54 mm Hg), tachypneic (36/min), and tachycardic (110/min). He has no signs of meningismus but is oriented only to person. A stat chest x-ray shows a left lower lung consolidation consistent with pneumonia. The plan is to start empiric antibiotics and perform a lumbar puncture to rule out bacterial meningitis.
What antibiotic regimen should be started to treat both pneumonia and meningitis?
Pneumonia: Should be thinking about macrolides (azithromycin) or beta-lactam antibiotics
Meningitis: May need to include vancomycin and ceftriaxone or cefotaxime as well (emphasized good CNS penetration with 3rd and 4th generation cephalosporins, which is critical in accessing the infection in the CNS)
With an approach which covers both of these, it is reasonable to use all of them
Does the history of amoxicillin rash affect the antibiotic choice? Why or why not?
- Probably not worried about cross sensitivity
- This was not an anaphylactic reaction
- We have a pretty serious infection going on here, so we don’t care about a mild rash
- Good chance they won’t react at all, but if they do, we’ll take the rash and treat the infection
Case 3
A 59-year-old woman presents to an urgent care clinic with a 4-day history of frequent and painful urination. She has had fevers, chills, and flank pain for the past 2 days. Her physician advised her to come immediately to the clinic for evaluation. In the clinic she is febrile (38.5°C [101.3°F]) but otherwise stable and states she is not experiencing any nausea or vomiting. Her urine dipstick test is positive for leukocyte esterase. Urinalysis and urine culture are ordered. Her past medical history is significant for three urinary tract infections in the past year. Each episode was uncomplicated, treated with trimethoprim-sulfamethoxazole, and promptly resolved. She also has osteoporosis for which she takes a daily calcium supplement. The decision is made to treat her with oral antibiotics for a complicated urinary tract infection with close follow-up.
Given her history, what would be a reasonable empiric antibiotic choice?
- This is a UTI, the physician treats it as a “complicated” UTI (it may or may not be considered as a complicated case, just depends on the practitioner)
- Antibiotics: Fluoroquinolone, TMP-SMX *** (there is no difference between the drugs for uncomplicated and complicated)
- Know the sulphonamides MOA *** (emphasized this)
- If the TMP-SMX was not working, the next first choice would be the fluoroquinolone
Depending on the antibiotic choice are there potential drug interactions?
If they take the FLUOROQUINOLONES with the calcium, it will NOT be absorbed
Do NOT take them together **
KNOW THIS DRUG-NUTRIENT INTERACTION **
