Pharyngitis Phacts

I'm looking to hit a couple "hot-button" topics coming up. As well I'm trying to set up a LLSA review forum. I'd like to do a little review of pharyngitis. I feel that this is one topic where I see a huge variation in work-ups and evaluation. I think we probably over-test and over-treat this diagnosis. So let's review this, shall we?

• Let me start off by saying this is a chief complaint that enables us to perform a lot of patient education. I think you'll find that sitting down with a patient or parent for five minutes will save them time (waiting for lab tests), you time (quicker dispositions) and money (paying for said lab tests and the antibiotics they probably don't need). Also the antibiotic choices I see are varied and too aggressive for a pharyngitis that is a) probably a virus b) self-limiting and likely will get better on its own and c) too broad spectrum when treating one specific, easily treated bacteria. These are important points to consider the next time you're tempted to test and treat.
• MOST CASES OF PHARYNGITIS ARE DUE TO VIRUSES. This should probably be the first and last sentence out of your mouth to the patients.
• The majority of cases of acute pharyngitis are self-limiting and only need supportive care (again an important discussion point).
• Seven million cases of pharyngitis visits annually in the US.
• Common viruses behind acute pharyngitis: Coxsackievirus, echovirus, adenovirus, HSV, and EBV (usually associated with LAD, splenomegaly). Consider mono as well (especially in patients with posterior cervical LAD).
• Group A Beta-Hemolytic Strep (GABHS) is the bacterial infection that we end up over-treating for.
• GABHS is the cause of only 15-30% of acute pharyngitis in pediatrics. It causes only 10% of adult acute pharyngitis cases. These are nice facts to present to patients/parents during your educational talk with them.
• Other bacterial causes are Group C, Group G Beta-hemolytic strep, Corynebacterium diphtheriae, Mycoplasma, Chlamydia and Neisseria gonorrhoeae (if you have to ask how it got there, I'm not going to be the one telling you).
• Pharyngeal diphtheria typically has the grayish brown pseudomembrane. They can have significant soft tissue edema and cervical LAD resulting in the "bull-neck" appearance.
• Most cases of pharyngitis occur in winter and early spring.
• Group C hemolytic strep can cause outbreaks (especially in teenagers and adults).
• I'm not going to go over the typical clinical features of acute GABHS. I think we're all well versed on this.
• Scarlet Fever: A URI due to GABHS with a classic "sandpaper" rash. This occurs because of a pyrogenic exotoxin released by GABHS. The occurence of Scarlet fever has significantly decreased in frequency and virulence over the years.
• The rash associated with Scarlet Fever blanches and is typically more pronounced in the flexor surfaces of elbows, axilla and groin.
• Scarlet Fever rash typically has its onset 24-48 hours after the first signs of the pharyngitis. It'll typically last 3-4 days and results commonly in desquamation.
• The tongue can commonly give a "strawberry" appearance due to desquamation and promient papillae.
• So since we know that viruses cause the majority of acute pharyngitis, are there clinical signs that suggest a viral etiology? I'm glad you asked...
• The Centor criteria: No longer should these be pimp questions, but educational tools for your patients. The four Centor criteria are a) history of fever b) tonsillar exudates c) no cough, and d) tender anterior cervical lymphadenopathy (lymphadenitis). If the patient meets all four criteria, it's more likely bacterial. Other symptoms consistent with viral pharyngitis are headaches, coryza, cough, rhinorrhea, myalgias, conjunctivitis, exanthem, and odynophagia.
• Some have taken the position that you should not test or treat patients with none or only one of these criteria, since these patients are unlikely to have GABHS infection. Again, if they have met ZERO OR ONE criteria, do not bother testing or treating with antibiotics. Supportive care only.
• For patients with two or more criteria the following three options are recommended by Internal Medicine docs: OPTION #1) Test patients with two, three, or four criteria by using a rapid antigen test, and limit antibiotic therapy to patients with positive test results. OPTION #2) Test patients with two or three criteria by using a rapid antigen test, and limit antibiotic therapy to patients with positive test results or patients with four criteria (don't test, just treat); or OPTION #3) Do not use any diagnostic tests, and limit antibiotic therapy to patients with three or four criteria.
• My personal feeling is that these are a little conservative even for the simple fact that individuals that meet ALL FOUR Centor criteria still only 50% of the time have GABHS. Thus why not simply avoid testing all patients and simply treat the ones who have only met ALL FOUR Centor criteria? Some docs (including myself) take this approach.
• Testing: Sensitivity of RSA is 90-95% when done correctly (big caveat). Specificity of most RSA's are 60-95%. Also no test can distinguish those infected with acute GABHS and those that are carriers.
• Throat cultures: why bother getting them? They typically need 48 hours to be accurate. Also since RSA's are typically 95% sensitive, what's the benefit. By the time you get the results back, they'll probably confirm what you already know. Also only 50% of positive throat cultures are acutely infected (people can also be carriers).
• Treatment: So if symptoms typically resolve in 3-4 days after treatment, why bother? Antibiotics have been shown to shorten the course in 13% by a whopping one day. So again, why bother treating? The one reason to treat is due to the possibility of acute rheumatic fever secondary to GABHS (as a quick aside antibiotics DOES NOT change the incidence of glomerulonephritis secondary to GABHS). With regards to the treatment to prevent rheumatic fever, antibiotics can be delayed up to nine days after the onset of symptoms and still be effective. Other reasons are because GABHS can progress to a PTA, retropharyngeal abscess, sinusitis, OM, or mastoiditis. Again, rare sequelae to GABHS.
• Acute rheumatic fever typically doesn't occur for 2-4 weeks after onset of the acute pharyngitis. Post-streptococcal glomerulonephritis doesn't occur for 3 weeks until onset of original symptoms. The incidence of rheumatic fever is typically 0.3% (up to 3% in epidemic outbreaks). Still very small when you consider that only 10-15% of the cases will be due to GABHS AND only 0.3% of those patients could develop rheumatic fever. Your patients probably will have a greater chance of having an anaphylatic reaction to the antibiotics you give them.
• IF despite this blog, you're still determined to treat you have only two accetable choices of antibiotics. You should give everyone PCN unless they're allergic. IF they're allergic to PCN then the only reasonable option is Erythromycin. Do not use amoxicillin, cephalosporins, maxipime, etc. GABHS has never become resistant to PCN in cultures. Therefore why use a more broad-spectrum, expensive antibiotic when PCN works perfectly fine?
• If you're going to treat you have a choice of either PCN V (oral) or G (IM). I'm a personal fan of IM (I know, I'm sadistic). To me, it's easier to do a one time shot, versus qid oral dosing for ten days. If you ever look at studies that show how compliant patients are when taking 40 doses of a medicine, you'd not even bother writing the Rx. Also if the patient is going to be better in 3-4 days, do you really forsee them continuining a ten day course?
• Doses: PCN G 1.2 million units (greater than 27 kg) IM or 0.6 MU if less than 27 kg) one time IM.
• PCN V 250 mg PO bid/tid x 10 days in children; In adults 250 mg PO tid/qid x 10 days or 500 mg PO bid x 10 days. (Again is it really worth it?)
• Again, if they're PCN allergic, erythromycin is the best alternative.
• Thus, if you take away some key points from this, review the Centor criteria with the patient/parents, explain the disease epidemiology, the logic behind not testing and whether antibiotics are warrented. You probably can significantly shorten LOS in the ED, increase patient satisfaction and decrease patient cost.
• Hope this was helpful. I'm out.