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Physician Assistant CME

Prescribing Antibiotics for Common Infections

John Bielinski, MS PA-C By September 5, 2018November 27th, 2018No Comments
Prescribing Antibiotics for Common Infections

One of the biggest ways I feel I can serve my readers and my board review attendees is to continue to cover common infections and recent antibiotics. Are we up-to-date on what we’re prescribing?

I just want to start with this point: amoxicillin is a pretty safe medicine. Cephalosporins are pretty safe, as are macrolides. Fluoroquinolones are dangerous; proceed with caution. Fluoroquinolones are good for everything: gram-positive, gram-negative, atypicals, Pseudomonas. But you need to look at some of the side effects and proceed with caution.

  • QT prolongation
  • Tendon rupture: You put a young lady on a fluoroquinolone, she pops her ACL and can’t play college soccer anymore.
  • Transaminitis: Their AST and SLT are up and it can mess with their liver.
  • Teratogenic: Clearly, we want to avoid prescribing to pregnant woman and kids under 18.
  • Dysglycemia: This is such a big deal that the FDA recently increased its warning about dysglycemia. Proceed with caution with fluoroquinolones for diabetics.


What needs to be the first thing out of your mouth when faced with cellulitis? You need to know if the patient is a diabetic or not. Diabetic cellulitis almost always comes in. That’s a very easy admission, so it’s one of the first things I want to hear.

When we have someone with cellulitis, I need to know if it’s focal or systemic. Focal isn’t a big deal. With systemic cellulitis, they’re going to have a fever, chills, rigors, the tachypnea. I want to know three things: if they have bacteremia, if they have lymphangitis and if they’re experiencing malaise.

We use these three things to pick up on sick people early. A good provider doesn’t put out fires. A good provider prevents the fires from starting in the first place. Lymphangitis needs to be in your terminology. Are there stripes up the legs?

When you’re coming down with a cold and you just feel sick, there’s a medical term for that: malaise. For a patient with lymphangitis, that’s not a cold, that’s early sepsis. They need an IV dose of antibiotics. With a fever, chills, rigors and a high white count, it’s easy to pick up on cellulitis early. Maybe observe them, or bring them back the next day.

We know cellulitis is plaque-like structures that spread rapidly, usually in a unilateral pattern. Often the patient’s febrile with lymphangitis, which needs to be part of your documentation. According to the literature, lower extremity cellulitis is often a tinea infection on the feet. Really look for it in between the cracks of the toes.

Right now, clindamycin, Bactrim and doxy are all options for treatment. What’s better, clindamycin or Bactrim? We don’t know. They’re comparable based on literature.

UTI in Females

How do you know if they have a pyelonephritis? They will be sick; there will be rigors, chills, fever, CVA and tenderness because kidneys are super vascular, just like the lungs. Do a urine culture and always consider an STD. Could it be general urinary or a urethritis? A urethritis is an STD, while cystitis is your UTI.

Sanford’s is still suggesting Bactrim as a good, viable medicine. If there’s a resistance of greater than 20% in your area, you should think about nitrofurantoin. Do not use nitrofurantoin during your last trimester of pregnancy because of the risk for hemolytic anemia in newborns. Fluoroquinolones are not recommended as a primary antibiotic for UTIs, as the resistance patterns are comparable to those of Bactrim.


I want to warn you about something. I’ve admitted people to the hospital because of this. Sulfamethoxazole/trimethoprim (Bactrim, Sulfatrim, Bactrim DS) cannot be combined with another medicine. If it’s combined with another medicine, it’s potentially life-threatening after two doses. You can never combine Bactrin and warfarin because the INR will go to nine in two doses.


Pyelonephritis is greater than 102 with CVA tenderness. When you’re testing for CVA tenderness, you’re going to pop, pop, pop. If I hit anybody in their kidney, they’re going to jump. My advice is to percuss down. Don’t whack them right in the kidney; start up on the ribs. Give them a couple shots on the upper part of their back and percuss down to it. You’ll get a much more sensitive exam.

You want to do urine and blood cultures. Males should not have pyelonephritis, so it’s a flag that should make you think, “This could be something bad. I better talk to urology.” You might want an intervascular study or some kind of CAT scan. We have a lot of complications from pyelonephritis. You want to look for obstructions and underlying renal disease. If it’s immunosuppressive pyelonephritis, it’s concerning. If they have a kidney stone and a pyelonephritis, that’s an emergency.

Pyelonephritis and Kidney Stones

If someone has a fully obstructive, 100-millimeter, kidney stone, how long can the stone stay in there before causing permanent kidney damage? The literature shows two weeks. But a kidney stone and pyelonephritis together is an emergent life-threatening problem, as bad as meningitis or ascending cholangitis. It needs to be drained immediately with either a stent or a percutaneous nephrostomy tube. Otherwise, they’ll die very quickly.

Pyelonephritis Treatment

You can make an argument to admit pyelonephritis patients. They get better pretty quickly with a gram of ceftriaxone and a bunch of fluids. I can perk them up in about an hour. For outpatient treatment, ciprofloxacin, Levaquin or moxifloxacin are acceptable. In clinical settings where fluoroquinolone resistance is greater than 10%, they’re recommending ceftriaxone. I like ceftriaxone. Gentamicin is still a very good antibiotic, especially for gram-negative sepsis. It’s dirt cheap and covers pseudomonas.

Other Antibiotic Pearls

You’d never use ciprofloxacin for a skin infection because it doesn’t cover gram-positives well. As I mentioned above, proceed with caution with fluoroquinolones because of the risky side effects. They’re causing more trouble than we thought with blood sugars. That’s already acknowledged overseas in Europe and we’re catching up now.

There’s no published evidence supporting prophylaxis. A local cellulitis doesn’t necessitate pulling the trigger on antibiotics. Hand surgeons love a gram of Ancef, but the literature doesn’t support it.

There is an exception to this: endocarditis prophylaxis. We need to consider prosthetic hearts, heart valves. I don’t care if it’s mechanical or a bioprosthetic. You should cover it with antibiotics. Your notes have to reflect that you’re aware of a patient’s heart valve and that you’re concern about germs getting in. It is very reasonable to say, “Because they have an artificial valve, I’m going to cover them for skin pathogens.” I think that’s super high-end medicine.

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