What it is:Three separate infections that share the same setup story. Acute otitis media (middle ear), pharyngitis (throat, specifically group A strep), and acute bacterial rhinosinusitis (sinuses) are the bread-and-butter ENT infections you'll see constantly in primary care, urgent care, and community pharmacy triage.
The core problem:A virus does the initial damage in all three. It wrecks mucociliary clearance or blocks a drainage pathway (eustachian tube, sinus ostia), and bacteria move into the space that opens up. Most cases never get that far and stay viral. The clinical skill isn't knowing which antibiotic, it's knowing whether this particular patient is in the bacterial minority who actually needs one.
What you do about it:Treat pain in every single case regardless of cause. Apply the specific criteria for each disease to sort bacterial from viral. When antibiotics are warranted, amoxicillin (plain or with clavulanate) is first line for all three, dosed against the same recurring organisms: Streptococcus pneumoniae, Haemophilus influenzae,and Moraxella catarrhalis(group A strep instead, for pharyngitis).
One idea drives this entire chapter: "virus first, judgment second, antibiotic third."Every diagnostic criterion and every watch-and-wait pathway here exists to stop reflexive antibiotic prescribing for infections that were going to resolve on their own.
Before the details, see how these line up next to each other. Notice how two of the three share the exact same bacteria and the exact same first-line logic, while pharyngitis plays by different rules entirely.
| Disease | Site | Bacteria (when bacterial) | How much is bacterial | Diagnostic anchor |
|---|---|---|---|---|
| Acute otitis media | Middle ear | S. pneumoniae, H. influenzae(nontypeable), M. catarrhalis | Bacteria found in >80% of cases | Middle ear effusion + bulging or acutely painful tympanic membrane |
| Pharyngitis | Oropharynx / nasopharynx | Group A Streptococcus(GAS, S. pyogenes) | 10–30% of pediatric cases, 5–15% of adult cases | Positive RADT or throat culture, guided by pretest probability |
| Acute bacterial rhinosinusitis | Paranasal sinuses | S. pneumoniae, H. influenzae | ~50–70% of bacterial cases from these two organisms | Symptoms ≥10 days without improvement, severe onset, or "double sickening" |
The same two organisms(S. pneumoniaeand H. influenzae) drive both otitis media and sinusitis, which is exactly why they share a first-line drug and the same resistance logic. Pharyngitis is the odd one out. It's GAS, which has stayed reliably penicillin-susceptible for decades, so first line stays plain penicillin or amoxicillin instead of a clavulanate combination.
All three usually start the same way: a viral upper respiratory infection impairs the mucociliary apparatus and causes dysfunction of a drainage structure. In the ear, that's eustachian tube dysfunction, which lets fluid build up behind the drum instead of draining into the nasopharynx. In the sinuses, it's obstruction of the ostia that normally keep mucus moving out. Once fluid or mucus sits still, it becomes a place for bacteria to multiply instead of getting cleared. This is why otitis media and sinusitis are so often described together and treated with the same drugs; they're mechanically the same problem in two different locations. Children get otitis media far more often because their eustachian tube is shorter and sits more horizontally, so it drains less efficiently to begin with.
| Organism | Resistance mechanism | Why it matters for drug choice |
|---|---|---|
| S. pneumoniae | Altered penicillin-binding proteins | Resistance is relative, not absolute. More drug can still overcome it, which is why high-dose amoxicillin is the fix instead of switching drug class. |
| H. influenzae | β-lactamase production | Plain amoxicillin gets destroyed before it can work. Needs clavulanate to inactivate the enzyme. |
| M. catarrhalis | β-lactamase production | Same problem, same fix as H. influenzae. |
That table isthe prescribing logic. High-dose amoxicillin beats S. pneumoniaeby brute concentration, since its resistance is a matter of degree. Amoxicillin-clavulanate beats H. influenzaeand M. catarrhalisbecause clavulanate disables the β-lactamase enzyme that would otherwise chew up amoxicillin before it ever reaches the bacteria. That's the entire reason treatment failure, recent antibiotic exposure, or other risk features push you toward the clavulanate combination rather than just raising the amoxicillin dose further.
Otitis media isn't one thing. Three subtypes get lumped together and mixing them up is a common mistake.
| Subtype | Defined by |
|---|---|
| Acute otitis media (AOM) | Middle ear effusion, plusacute signs of infection and evidence of middle ear inflammation |
| Otitis media with effusion (OME) | Non-infected fluid buildup without acute infection signs. Often follows a URI or allergies. Can self-resolve in 4–6 weeks; if it becomes infected, it becomes AOM |
| Chronic otitis media | Persistent middle ear disease beyond the expected acute course |
Diagnose AOM when there is middle ear effusion andeither: (1)moderate-to-severe bulging of the tympanic membrane or new-onset otorrhea not explained by otitis externa, or (2)mild bulging of the tympanic membrane plus ear pain within the last 48 hours, or intense erythema of the tympanic membrane.
| Infants / young children | Older children / adults |
|---|---|
| Fussy, irritable, crying more than usual, trouble sleeping, tugging at the ear, fever, otorrhea if the drum ruptures | Ear pain, fullness or pressure in the ear, hearing impairment, otorrhea if the drum ruptures; some report vertigo, nystagmus, or tinnitus |
These get mixed up constantly. Otitis externais infection of the ear canal(Pseudomonas and S. aureus, roughly 98% bacterial), comes on fast (under 48 hours), and its signature exam finding is severe pain when the pinna is pulled or the tragus is pressed, plus canal edema and erythema. AOMis behind an intact (often bulging) drum, pinna traction doesn't reproduce the pain, and it's treated with an oral or IM/IV antibiotic instead of topical drops. If a question describes pain on pulling the ear, that's externa, not media.
Give antibiotics quickly when the diagnosis is certain. Withhold them, at least initially, when it isn't. That single sentence is the entire watch-and-wait philosophy for AOM in one line.
Pain control is not optional and not an afterthought. Offer acetaminophen or an NSAID like ibuprofen early, on a schedule rather than only as needed, for every AOM patient regardless of whether they're getting an antibiotic. Decongestants and antihistamines are not recommended; they don't help clear the middle ear effusion and add adverse effects for no benefit.
| Initial diagnosis | ||
| Amoxicillin | 80–90 mg/kg/day orally, divided twice daily | First line |
| Amoxicillin-clavulanate | 90 mg/kg/day amoxicillin + 6.4 mg/kg/day clavulanate, divided twice daily | First line if certain criteria present (see callout below) |
| Cefdinir, cefuroxime, or cefpodoxime | Cefdinir 14 mg/kg/day (1–2 doses); cefuroxime 30 mg/kg/day (2 doses); cefpodoxime 10 mg/kg/day (2 doses) | Second line, or nonsevere penicillin allergy |
| Ceftriaxone | 50 mg/kg/day IM or IV for 1–3 days | Second line, or nonsevere penicillin allergy |
| Failure at 48–72 hours | ||
| Amoxicillin-clavulanate | 90 mg/kg/day amoxicillin + 6.4 mg/kg/day clavulanate, divided twice daily | First line |
| Ceftriaxone | 50 mg/kg/day IM or IV for 1–3 days | First line, or nonsevere penicillin allergy |
Go straight to high-dose amoxicillin-clavulanate instead of plain amoxicillin if the child has received amoxicillin within the last 30 days, has concurrent purulent conjunctivitis, or has a history of recurrent infection that already failed amoxicillin. All three point toward a β-lactamase-producing organism that plain amoxicillin won't touch.
Duration:in children at least 6 years old with mild-to-moderate AOM, a shorter 5- to 7-day course can be used. Short-course treatment is not recommended in children younger than 2 years, who need the full course.
Reassessment:check back at 48–72 hours. No clinical improvement by day 3 means switch the regimen, don't just wait longer on the same drug.
Most pharyngitis is viral (rhinovirus, coronavirus, adenovirus, herpes simplex virus among others) and self-limited. GAS is the most common bacterialcause, but bacterial causes overall are far less common than viral ones. Noninfectious throat irritation from allergens, GERD, smoking, or chronic mouth breathing can mimic pharyngitis too and doesn't need an antibiotic at all.
| Suggests GAS | Suggests viral |
|---|---|
| Sore throat, pain on swallowing, fever, headache, nausea/vomiting/abdominal pain (especially in children), erythema and inflammation of the tonsils and pharynx with or without patchy exudates, enlarged tender lymph nodes, red swollen uvula, petechiae on the soft palate, scarlatiniform rash | Conjunctivitis, coryza (runny nose), cough |
Confirm with a rapid antigen-detection test (RADT) and/or throat culture, which is the gold standard. In children younger than 3 years, a negative RADT should be followed by a throat culture before ruling GAS out. The Modified Centor (McIsaac) scoreis used to decide who needs testing in the first place: a score of 0–1 needs no further testing, 2 makes testing optional, and 3–4 means perform a RADT and/or culture.
Antimicrobial therapy should be limited to patients with clinical andepidemiologic features of GAS pharyngitis, preferably backed by a positive test. Treating a sore throat blind, without testing, is exactly how GAS pharyngitis becomes a source of unnecessary antibiotic exposure for what is usually a viral illness.
Goals of treatment: improve signs and symptoms, minimize adverse drug reactions, prevent transmission to close contacts, and specifically prevent acute rheumatic fever and suppurative complications.
Suppurative:peritonsillar abscess, retropharyngeal abscess, cervical lymphadenitis, mastoiditis, otitis media, rhinosinusitis, and necrotizing fasciitis. Nonsuppurative:acute rheumatic fever, acute glomerulonephritis, reactive arthritis. Preventing rheumatic fever specifically is the real reason antibiotics matter here, even though the sore throat itself would likely resolve without them.
Pain is often the whole reason a patient shows up, so lean on acetaminophen and NSAIDs. Nonpharmacologic measures matter too: rest and fluids, warm liquids, ice chips or popsicles, non-medicated lozenges (choking hazard, avoid in young children), a cool mist vaporizer, saltwater gargles (¼–½ teaspoon of salt per 8 oz water), and honey in warm beverages (avoid under age 2). Topical anesthetics and antiseptics can help with local pain and soothing.
| Preferred if no penicillin allergy | |||
| Penicillin V | Children 250 mg twice or three times daily; adults 250 mg four times daily or 500 mg twice daily | Oral, 10 days | IB |
| Penicillin G benzathine | <27 kg: 0.6 million units; ≥27 kg: 1.2 million units | IM, one dose | IB |
| Amoxicillin | 50 mg/kg once daily (max 1000 mg), or 25 mg/kg (max 500 mg) twice daily | Oral, 10 days | IB |
| Penicillin allergy | |||
| Cephalexin | 20 mg/kg/dose twice daily (max 500 mg/dose) | Oral, 10 days | IB |
| Cefadroxil | 30 mg/kg once daily (max 1 g) | Oral, 10 days | IB |
| Clindamycin | 7 mg/kg/dose three times daily (max 300 mg/dose) | Oral, 10 days | IIaB |
| Azithromycin | 12 mg/kg once daily (max 500 mg) day 1, then 6 mg/kg once daily (max 250 mg) days 2–5 | Oral, 5 days | IIaB |
| Clarithromycin | 15 mg/kg/day divided twice daily (max 250 mg twice daily) | Oral, 10 days | IIaB |
Penicillin, amoxicillin, the cephalosporins, and clindamycin all run 10 days. The two exceptions: benzathine penicillin Gis a single IM dose, and azithromycinis a compressed 5-day course. Even though symptoms often improve within a couple of days on any of these, the full course still matters, since rheumatic fever prevention depends on actually eradicating the organism, not just easing symptoms. Macrolide resistance in GAS varies locally, so check local susceptibility before defaulting to azithromycin or clarithromycin.
Amoxicillin-clavulanate, clindamycin, penicillin plus rifampin, or benzathine penicillin G plus rifampin can be used for recurrent episodes, to maximize eradication in potential carriers and to cover copathogens producing β-lactamases that can shield GAS from penicillin.
| Regimen | Dose |
|---|---|
| Clindamycin | 20–30 mg/kg/day divided three times daily (max 300 mg/dose) for 10 days |
| Amoxicillin-clavulanate | 40 mg/kg/day divided three times daily (max 2000 mg/day of amoxicillin) for 10 days |
| Penicillin V + rifampin | Penicillin V 50 mg/kg/day in 4 doses for 10 days (max 2000 mg/day); rifampin 20 mg/kg/day once daily for the last 4 days (max 600 mg/day) |
| Penicillin G benzathine + rifampin | Penicillin G benzathine as a single IM dose (weight-based as above); rifampin 20 mg/kg/day divided twice daily during the last 4 days of treatment (max 600 mg/day) |
Follow-up:not routinely needed for index cases or asymptomatic contacts. A throat culture 2–7 days after finishing antibiotics is warranted only if the patient remains symptomatic or symptoms recur after seeming to resolve.
Untreated GAS pharyngitis usually resolves in 3–4 days on its own. Antibiotics only shave off about 0.5–2.5 extra days. The point of treating is not speed. It's preventing rheumatic fever and suppurative complicationsand cutting the contagious period short.
"Rhinosinusitis" is the preferred term over "sinusitis" because the nasal mucosa is almost always involved too. Most cases are viral. Telling viral from bacterial is the entire diagnostic task, since the two need different management.
A patient with a typical cold that seemed to be getting better, then suddenly worsens again around day 5 or 6, is describing double sickening. That second wave, on top of a course that was already improving, is the giveaway for a bacterial infection layered onto a resolving virus. Don't confuse this with a cold that just never got better in the first place; that's pattern 1 (persistent), not double sickening.
Purulent anterior nasal discharge, purulent or discolored posterior nasal discharge, nasal congestion or obstruction, facial congestion or fullness, facial pain or pressure, fever, headache, ear pain/pressure/fullness, halitosis, dental pain, cough, and fatigue. For contrast, uncomplicated viralrhinosinusitis typically improves within 7–10 days without any of these persistent or worsening patterns.
Goals: reduce signs and symptoms, restore drainage through the sinus ostia, limit antibiotics to patients likely to benefit, eradicate infection when antibiotics are indicated, minimize illness duration, and prevent progression to chronic disease.
Adjuncts that help:intranasal saline irrigation (physiologic or hypertonic) and intranasal corticosteroids, especially useful alongside antibiotics in patients with a history of allergic rhinitis.
Topical or oral decongestants and antihistamines are not recommendedas adjuncts for acute bacterial rhinosinusitis. They can dry out the mucosa and actually disturb clearance of the very secretions you're trying to move out.
High-dose amoxicillin-clavulanate is preferred (over standard dose) when any of the following apply: geographic regions with high endemic rates (≥10%) of invasive penicillin-nonsusceptible S. pneumoniae, severe infection, daycare attendance, age under 2 or over 65, recent hospitalization, antibiotic use within the last month, or immunocompromised status. Doxycycline is a reasonable second-line option in adults, but should be avoided in children.
| Children - initial empirical therapy | ||
| Amoxicillin-clavulanate | 45 mg/kg/day orally twice daily | First line |
| Amoxicillin-clavulanate | 90 mg/kg/day orally twice daily | Second line (high-dose criteria) |
| Children - β-lactam allergy | ||
| Clindamycin + cefixime or cefpodoxime | Clindamycin 30–40 mg/kg/day three times daily, plus cefixime 8 mg/kg/day twice daily or cefpodoxime 10 mg/kg/day twice daily | Nontype 1 allergy |
| Levofloxacin | 10–20 mg/kg/day orally every 12–24 hours | Type 1 allergy |
| Children - resistance risk or failed initial therapy | ||
| Amoxicillin-clavulanate | 90 mg/kg/day orally twice daily | |
| Clindamycin + cefixime or cefpodoxime | Same dosing as above | |
| Levofloxacin | 10–20 mg/kg/day orally every 12–24 hours | |
| Children - severe, requiring hospitalization | ||
| Ampicillin-sulbactam | 200–400 mg/kg/day IV every 6 hours | |
| Ceftriaxone | 50 mg/kg/day IV every 12 hours | |
| Cefotaxime | 100–200 mg/kg/day IV every 6 hours | |
| Levofloxacin | 10–20 mg/kg/day IV every 12–24 hours | |
| Adults - initial empirical therapy | ||
| Amoxicillin-clavulanate | 500/125 mg three times daily, or 875/125 mg twice daily | First line |
| Amoxicillin-clavulanate | 2000/125 mg twice daily | Second line (high-dose criteria) |
| Doxycycline | 100 mg twice daily, or 200 mg once daily | Second line |
| Adults - β-lactam allergy | ||
| Doxycycline | 100 mg twice daily, or 200 mg once daily | |
| Levofloxacin | 500 mg once daily | |
| Moxifloxacin | 400 mg once daily | |
| Adults - resistance risk or failed initial therapy | ||
| Amoxicillin-clavulanate | 2000/125 mg twice daily | |
| Levofloxacin | 500 mg once daily | |
| Moxifloxacin | 400 mg once daily | |
| Adults - severe, requiring hospitalization | ||
| Ampicillin-sulbactam | 1.5–3 g IV every 6 hours | |
| Ceftriaxone | 1–2 g IV every 12–24 hours | |
| Cefotaxime | 2 g IV every 4–6 hours | |
| Levofloxacin | 500 mg once daily | |
| Moxifloxacin | 400 mg once daily | |
Duration:5–7 days for most uncomplicated adult cases. Children still need a longer course, 10–14 days. If symptoms persist or worsen after 48–72 hours of appropriate therapy, reevaluate and switch to an alternative antibiotic.
| Disease | When to check back | Watching for |
|---|---|---|
| AOM (watchful waiting) | 48–72 hours after diagnosis | Worsening symptoms → start antibiotics if previously deferred |
| AOM (on antibiotics) | 48–72 hours after starting therapy | No clinical improvement by day 3 → switch regimen, don't extend the same drug |
| Pharyngitis | 3–4 days without antibiotics, sooner with | Failure to improve or recurrence → throat culture 2–7 days after completing therapy |
| Rhinosinusitis | 48–72 hours after starting therapy | No improvement or worsening → reevaluate, consider an alternative antibiotic |
| Rhinosinusitis (untreated/observed) | Ongoing through the illness | Crossing the 10-day mark without improvement, or double sickening → reclassify as bacterial |