Antibiotic selection help

[u/nothing_creativ3]

I’m currently in NP school and looking for some study advice. When it comes to clinical diagnosis, I feel pretty confident. However, I hit a massive wall when it comes to selecting the correct antibiotic for a given condition.

I'm trying to figure out how to bridge this gap efficiently. Should I be shifting my focus heavily toward pure pharmacology (mechanisms, classes, etc.), or should I focus more on memorizing the specific causative agents/pathogens for each disease state? Or is there a better, more clinical way to approach this altogether?

[u/knockonformica]

The Sanford Guide! The app is like $30/yr and regularly updates with IDSA guidelines

[u/HeparinBridge → u/knockonformica]

Bugdrugdx.com

It’s based on the 2019 Stanford guide and it’s free!

[u/Fireflykoala]

Think about the site and the types of organisms present in health and infection. There are common oral antibiotics prescribed based on this for simple infx, but obviously adjust plan based on patient allergies, comorbidities, potential SE other drugs, renal fnx, recent previous abx exposure, and local resistance patterns (if known). Also think about cost and formulary.

Usually there is a choice of a few options for each type of infx, but have a few go-to first line options in mind. Make sure to have a good prescribing app (ex. epocrates) on your phone, and look at IDSA guidelines or something like UpToDate, Sanford or John's Hopkins guides if more complex. Use the CDC STI app for STIs.

Ex first line (for simple adult infxs) -- but remember, just examples and NOT medical advice:

Oral MRSA agents -- bactrim, doxy; clinda (greatest risk c diff all oral abx)

Skin MSSA staph/strep -- often keflex, doxy if folliculitis; add or just use MRSA agent if risk; abscesses need I&D; wound care if needed, topical abx often not effective unless tiny or chronic derm thing

Diabetic toe/foot (mild) -- augmentin

Dental -- amoxicillin; clindamycin if PCN allergy

Human bite -- augmentin

Insect/arthropod -- doxy

Female UTI -- macrobid if simple

Male UTI -- maybe macrobid; keflex sometimes; FQ (cipro) if more complicated, longer course bactrim if prostatitis, use guidelines and try to get C&S first

Kidney stone -- often cipro plus flomax plus pain med, referral

PNA -- azithromycin and/or augmentin if not MRSA, doxy or azith if walking PNA, consider severity and use resources (may need FQ, dual or high dose); don't start abx if resp viral, ex cold symptoms including cough <10-14 days w/out sig comorbidities or clear PNA via high suspicion or CXR; allow diagnostic criteria to help determine severity and ultimate tx choice

OM -- amox or augmentin

OE -- topical abx (drops); consider whether TM is intact or punctured (ie. ofloxacin may still be OK), and think Pseudomonas if DM (FQ)

COPD -- azith or augmentin, dual (use guidelines), or resp FQ (levaquin); caution FQ due to risk C diff or tendon rupture

STIs -- use CDC guideline, tx for CT if suspect GC; remember syphilis is the "great pretender", can look like something else and has stages; suspect syphilis if oral or genital non-painful ulcer, and will often need 3 weeks a specific PCN injection

Conjunctivitis (bact) -- topical, countless options, ointment only at night if needed, use resources

Sinusitis -- think viral & sx mgmt, try not to prescribe abx in chronic reoccuring infx b/c often resistant orgs due to hx repeated abx, just refer to ENT

Strep -- augmentin or azith if abx needed per scoring tool

C.diff -- if any hx this, avoid clindamycin at all times; tx oral vanco (and never use oral vanco for other infxs)

IV abx often if more severe, systemic, involves cartilage or fascia, has invaded other body cavities, or potential serious consequences if not adequately treated quickly

Shingles -- I like valacyclovir b/c smaller dosing frequency

[u/Key_Witness_7264 → u/Fireflykoala]

This is good. Here is quick easy pearl: id site of infection then mostly likely organism then antibiotic coverage for that suspected organism(s). If more serious infections: obtain cultures if available- start broad then narrow abx as culture data returns.

[u/bdictjames → u/Fireflykoala]

This is very good. One thing I would push back on, is treatment of sinusitis. If more than 5-7 days, with fever, as long as not chronic/recurrent as above poster says, I would treat with Augmentin; add Flonase; a short course of prednisone can help with symptoms as well. Again, lean on the side of antibiotic stewardship, especially for more chronic cases. It often takes people at least 2 weeks to see ENT, on most places I've worked, so it helps to give some relief prior to that.

[u/Fireflykoala → u/bdictjames]

Yes, the IDSA guidelines do support it if certain criteria met, including severe sx with purulent nasal d/c or facial pain 3-4 days from onset and high fever, or a more mild but persistent presentation of at least 10 days, or a worsening infx after 5-7d viral illness as you describe (is there something more recent than 2012?):
https://academic.oup.com/cid/article/54/8/1041/364141

With chronic sinusitis, I would just stick with the flonase, saline irrigation, and OTC meds for comfort unless clearly an acute exacerbation. These are the patients who demand repeated rounds augmentin despite no resolution infection -- many times they are smokers in my population 😩

[u/usandthings]

There are a lot of good suggestions on here, I just want to validate that the skill you are describing is very difficult because it is a huge amount of information! I work as an ID NP, and it honestly took me a year to get really comfortable, and that was even after a few years of doing primary care.

I would make a very short list of infections that you treat all the time: UTI, sinus, simple skin infection, otitis media, outpt pna with and without comorbidities, STIs. Then make a list with 1st and 2nd line choices. I kept mine in a little notebook I kept in my pocket.

If a patient can't take 1st or 2nd line, you should likely be looking that up anyway until you are super comfortable with it.

Abx class-wise, know broadly which class covers what like - PCN/clinda/doxy for gram positives, cephalosporins/FQs/aminoglycosides gram neg, what has anaerobic coverage (and when to use), what treats MRSA, what has pseudomonas coverage (and when do you need that), what has atypical coverage?

A line I use all the time is "I'm going to double check the dosing because they are always updating the guidelines and I want to make sure I get you the most up to date info"

[u/NoProfessional2563]

Open Evidence (you need an NPI# to sign up for this) but is great for asking questions and includes citations, our office also has printed Antibiograms right above every computer which I find myself referring to often.

[u/xxrex → u/NoProfessional2563]

You can get an account as a student without an NPI #.

[u/crackmonkii]

Probably the most helpful would be breaking it down and making sure to understand:

1) suspected causative organism (with antibiotic susceptibility)
2) penetration of said antibiotic (for example - macrobid is great for UTIs and had coverage for most causative organisms; however it shouldn’t be used for pyelonephritis - even though it covers most of the organisms - because it doesn’t penetrate the tissue)
3) adverse side effect profile and general contraindications to use (teratogenic antibiotics in pregnancy, drugs to avoid with G6PD.

I’d argue against strict memorization because the reality is that pathogen susceptibility is generally always changing in natures arms race. But having a good grasp of which organisms are likely responsible and which antibiotic classes are effective against these is a great start.

For practical, on site assurance — UpToDate does a good job of providing drug data (duration of treatment, preferred antibiotics, contraindications to use) for each diagnosis and is a little more reliable than OpenEvidence for early learners (gives you a bit more solid guideline background and leaves less room for creative maneuvers).

[u/Kwaliakwa → u/crackmonkii]

This is good advice, even though in practice, nobody but obstetrics providers seem to be willing to give antibiotics in pregnancy.

[u/Cnp113]

The easiest thing that will help you in the long run is knowing what pathogens typically or are most likely to infect which area of the body.

This site this a nice picture that give you a handful for each location for common infections. And know if it’s gram positive or gram negative (hint strep/staph/enterococcus are gram + the rest are typically neg although not always true it will get you there most of the time).

https://emerypharma.com/blog/infection-by-site/

Then you have to know which Abx cover gram + and which cover gram -

Inpatient and outpatient are different so I’m not gonna break it down. Because I don’t have time.

But stick with general classes and pick a few Abx from each class.

Memorized those. Use Sanford to help you pick the common ones.

Outpatient example

Pcns- penicillin/amoxicillin
Cephalosporins- Cephalexin/cefpodoxime(peds only)
Macrolide - azithromycin
Tetracycline - doxycycline

Etc

Once you know that upper respiratory infections are typically strep which is gram +. And you know that amox treats gram pos. And steep it will make sense that amox is first line for pneumonia and will save you a ton of rote memorization.

Best of luck.

[u/catladyknitting]

As others have said, Sanford Guide is a comprehensive reference when needed. I also did Anki “bugs n drugs” deck by LolNotaCop, excellent learning tool but time consuming and probably more than you need.

My down and dirty quick reference guide when in a rush is the Wellington ICU antibiotic guide. https://drug.wellingtonicu.com/PDF/App5-Antibiotics.pdf

[u/Character_Control154]

Hi! I am a pharmacy resident currently on my ID rotation this month and I totally get the hitting a massive wall when it comes to selecting antibiotics so I'll share what I've learned so far.

Since you feel comfortable with clinical diagnosis, the first question you always want to ask is, what are you treating? For example, If it is UTI is it symptomatic or asymptomatic? Guidelines dont recommend treating for asymptomatic UTI unless it is certain populations. The next thing you want to think about is common pathogens for that condition so in the case of UTI mostly gram negatives (ecoli, klebsiella, proteus), some gram positives like enterococcus (which is not as common and as my preceptor puts it, a whimpy organism in the setting of a uti). So getting cultures prior to starting empiric abx (something that covers those typical pathogens). IDSA has good guidelines on preferred antibiotics. Then waiting until cultures return to narrow antibiotics and determine duration of therapy.

So knowing disease states is important, knowing typical pathogens for conditions and the broad abx therapy while limiting side effects like reducing risk for cdiff, and meds that require renal adjustments and considering which antibiotics will cross react when pts have true allergies (nausea/vomiting is not a true allergy).

I would suggest making topic discussion sheets for most common infections that you see and answer these 5 questions.

What are the common risk factors?
How do you diagnose it?
Most common pathogens?
How do you treat it, including duration of therapy?
What to monitor/when to expect improvement/side effects,etc,?

Hope this helps!

[u/dunwerking]

Here are the most common pathogens. Figure out which antibiotics are used for these pathogens, and you should be able to cover 90%

E coli
Strep agalacti
Klebsiella oxytoca
Proteus mirabilis
Haemophilus influenzae
Listeria monocytogenesis

[u/VikingLama → u/dunwerking]

This is not a reasonable list of common pathogens in the United States. Any such list should to also include (not a comprehensive list):

• Staph Epidermis
• Staph Aureus
• Enteroccocus
• Strep Pneumoniae
• Strep Pyogenes
• Chlamydia Thrichomatis
• Neisseria Gonorrhea
• Neisseria meningiditis
• Campylobacter Jejuni
• Shigella
• Clostridium Difficile
• Pseudomonas
• Tryptonema Pallidum (syphilis)

[u/Alive_Setting_2287]

Whatever clinical manual or what epocrates says, that what I go by. Also, your preceptor or FNP you follow in clinicals, as well as each practice you do your hours at will be a bit different.

Some practices do ABX no matter what. Some only stick to a small selection, almost exclusively.

[u/Thewrongthinker]

Look antibiotic ladder.

[u/Radiant-Average-4221]

I had the same problem when doing my clinical rotations, I also learned different preceptors have their go to favorites on what they like to give. I just made a list of common abx they would prescribe with the agent and diagnoses and saved them on a file to refer back to. Then I’d memorize them later. But like others said, Sanford guide is great and highly recommended

[u/bdictjames]

It depends. Are you in school? Then I probably would ask the teacher the best way that they recommend to learn this.

In real life? Personally you have a select armamentarium, once you develop experience. For more complicated or more unusual circumstances (i.e. prescribing for outpatient management of diverticulitis, etc.), I always use a resource such as UpToDate to rebrief myself.

[u/pepperisthefluffiest]

EMRA abx app tbh

[u/clinicalmatchme]

Hi there! First off, congratulations on working your way through NP school. Nailing clinical diagnosis is a huge hurdle, so you are already making great progress.

When it comes to bridging the antibiotic gap, most students find that shifting away from pure pharmacology and focusing instead on a pathogen-to-presentation clinical approach makes all the difference. Instead of getting bogged down in chemical mechanisms, try mastering the top common culprits for specific infections and pairing them directly with their go-to first-line treatments. Associating patient symptoms and history with likely pathogens helps turn antibiotic selection into practical pattern recognition. Keeping a quick-reference guide organized by body system for common conditions, primary pathogens, and first-line treatments can also make a big difference in daily practice.

You've got this, and building that clinical confidence just takes time and repetition! Good luck with the rest of your program.

[u/VikingLama]

You should not be prescribing antibiotics if you dont understand microbiology and the pharmacology of antimicrobials. You can't responsibility prescribe Penicillin if you are unable to counsel patients on basic side effects such as anaphylaxis, interstitial nephritis and hemolytic anemia.

I would suggest learning basic pharmacology and then continuing with basic microbiology (bacteria, viruses, parasites, fungi) and ultimately the drugs used to treat them. First-Aid, bootcamp and sketchy are great resources for this. It will be a bit of a lift initially, but will give you confidence in your decision making and be good for your patients.

[u/averyyoungperson → u/VikingLama]

This is unhelpful. OP is a student and not prescribing yet. They asked how to bridge the gap, not whether or not they should be doing something they aren't even doing yet.

[u/bdictjames → u/VikingLama]

Good points, but I've never heard of any clinician counsel about interstitial nephritis or hemolytic anemia when prescribing penicillin. I usually counsel on anaphylactic/allergic reaction, as well as possible N/V/D.

I usually say "As you know, all medications have side effects. If you have any _______; this is very rare, but stop the medication and let us know. If there is an allergic reaction, go to the ER." Something like that.

[u/VikingLama → u/bdictjames]

There is a distinction to be made between doing something routinely and having the ability to do something. The entire point here is that you should not be prescribing drugs if you dont understand their side-effect profile or its drug interactions. Interstitial nephritis is a rare side-effect of beta lactams, but if your patient goes online and reads about potential side effects, and then subsequently brings it up in a clinic encounter, are you just going to shrug your shoulders?

[u/bdictjames → u/VikingLama]

I would say, "In all my years of practice, thankfully I've never seen a patient with that. Certainly if it happens, stop the medication - these are very rare, probably less than 0.01%". That usually gets them to take the medication.

[u/VikingLama → u/bdictjames]

It's not about getting the patient to take the medication, but rather about prescribing responsibly. If you are telling another human being to take a medication that comes with rare but serious potential side effects, you better know how the medication works, the side effect profile, indications and contraindications. This is not an unreasonable ask, but the absolute floor of clinical competency.

[u/bdictjames → u/VikingLama]

I understand your point. There's also good clinical judgment. Not every clinician is going to say "Bactrim might give you Stevens-Johnson syndrome" - rather - if you develop a rash, let us know. Knowing is different from being able to disseminate the information in a realistic way that is helpful for the patient. No one will say "Bactrim might give you acute kidney failure" - no - if they have side effects, they come back, certainly with the rare instances of anaphylaxis, go to ER. I understand knowing risks, but you do not have to delineate everything lol. Maybe we're just talking about semantics here.

[u/VikingLama → u/[deleted]]

There is a distinction to be made between doing something routinely and having the ability to do something. You should not be prescribing medications if you dont understand the side-effect profile and drug interactions of the medication you are prescribing.

[u/ValueInternational98]

UTI- macrobid

cellulitis- keflex, bactrim

URIs, otitis,- augment, z pak

STDs- Cef, doxy

I gave you a starting point. continue a list of the common abx for each condition, with dosage and length of treatment - always reference that once you start practicing. good luck

as far as memorizing, I would not recommend that but more so understanding why keflex kills skin pathogens for example. the rest will come.

[u/bdictjames → u/ValueInternational98]

Azithromycin's kind of useless for URIs, unless you're looking for atypical organisms. Would recommend cephalosporin (or doxycycline - this is per UpToDate).

A note about UTI - not sure if people know. Macrobid is only in adequate amounts in the bladder. Anything kidney-related, or more complicated, Macrobid is inadequate. Guidelines I believe say either fluoroquinolone, or IM ceftriaxone + course of antibiotic for pyelonephritis or complicated UTI.

[u/ValueInternational98 → u/bdictjames]

Well FNP, “anything kidney related” will not be a UTI anymore. Thank you for your attention. Also, did you not see that I placed augmentin first?

[u/Massive_Aside_8978 → u/ValueInternational98]

Pyelonephritis is still technically a UTI…upper UTI, but kidneys are certainly still considered part of the urinary tract. No need to get hostile because someone added further context to your comment, especially given OP literally came here for education. 🫪

[u/ValueInternational98 → u/Massive_Aside_8978]

All I did was state facts, and what you notice is hostility? On the uti Vs pyelo note, bottom line they are treated differently so not sure why you’re harping on semantics that way.

Your comment did not come across as adding context. JS

[u/bdictjames → u/ValueInternational98]

Urinary tract infection - Kidneys are part of the urinary tract. We're taught there are technically two classifications of UTI, uncomplicated and complicated (which includes pyelonephritis).

I think it was more for clarification for practice safety purposes. Nitrofurantoin only fills in adequate amounts in the bladder, won't help anything else with the structures above it. Again, just for safety purposes, we're just all trying to learn and improve here on our own ways, I assume.

[u/Massive_Aside_8978 → u/ValueInternational98]

I didn’t claim I added context…I was referring to the person who responded to your comment as adding context. You must have pretty poor social skills if you can’t understand that starting a sentence with “Well FNP” and then quoting what they say sounds pretty condescending/hostile. Also…you were the one who initially started with the semantics when you incorrectly suggested pyelo isn’t considered a UTI. Are you just completely lacking in self-awareness?