Medical School · Year 3 · Family Medicine · includes a quiz and discussion video

Seminar 03: Common Acute Complaints

Year 3: Family Medicine Clerkship

Learning Objectives

By the end of this seminar, students will be able to:

1. Evaluate and manage upper respiratory infections
2. Diagnose and treat urinary tract infections
3. Assess and manage acute low back pain
4. Recognize serious causes of common symptoms
5. Apply appropriate testing and treatment strategies
6. Practice antibiotic stewardship principles

Seminar Outline

I. Upper Respiratory Infections

Upper respiratory infections represent the most common reason for primary care visits and provide frequent opportunities to practice evidence-based management and antibiotic stewardship. The common cold is caused by over two hundred different viruses, with rhinoviruses accounting for the majority of cases, followed by coronaviruses, adenoviruses, and respiratory syncytial virus. Typical symptoms include rhinorrhea, nasal congestion, sore throat, and cough, which develop gradually and peak around day three to four of illness. The natural history involves symptom duration of seven to ten days, though cough may persist longer, and patients should receive education about expected timeline to reduce demand for unnecessary interventions. Understanding viral etiology is essential for appropriate management and for communicating with patients about why antibiotics will not help.

Symptomatic treatment provides the only evidence-based intervention for viral upper respiratory infections, as no antiviral treatments are available for common cold viruses. Nasal congestion responds to oral decongestants such as pseudoephedrine or topical decongestants such as oxymetazoline, though topical agents should be limited to three days to avoid rebound congestion. First-generation antihistamines like diphenhydramine may reduce rhinorrhea through anticholinergic effects but cause sedation. Sore throat may be managed with lozenges, warm salt water gargles, or systemic analgesics including acetaminophen or ibuprofen. Cough may respond to honey in patients over one year of age, while dextromethorphan provides modest benefit in adults. Adequate hydration and rest constitute reasonable general recommendations, though evidence for efficacy is limited.

Several commonly used interventions lack evidence of efficacy and should not be routinely recommended. Antibiotics provide no benefit for viral upper respiratory infections and cause harm through side effects, cost, and contribution to antimicrobial resistance, yet remain among the most frequently overprescribed medications. Vitamin C does not prevent colds when started after symptom onset and provides minimal treatment benefit. Zinc lozenges have shown modest benefit in some studies when started within twenty-four hours of symptom onset, but evidence remains inconsistent and side effects include nausea and altered taste. Echinacea products have not demonstrated consistent benefit in well-designed trials. Patients often expect treatment beyond symptomatic care, requiring effective communication about evidence and appropriate setting of expectations.

Red flags during evaluation of upper respiratory symptoms identify the minority of patients with serious conditions requiring different management. High fever exceeding one hundred three degrees Fahrenheit suggests possible bacterial infection rather than typical viral illness. Severe or worsening facial pain, particularly if unilateral, raises concern for bacterial sinusitis. Neck stiffness should prompt evaluation for meningitis, which may present with upper respiratory prodrome. Significant respiratory distress including tachypnea, accessory muscle use, or hypoxia requires evaluation for pneumonia or other lower respiratory conditions. Symptoms persisting beyond ten days without improvement suggest secondary bacterial infection. Proper identification of red flags ensures appropriate escalation while avoiding unnecessary intervention for self-limited viral illness.

<image>Panel A: Diagram showing viral etiology of common cold with rhinovirus, coronavirus, and other pathogens with their relative frequencies and typical symptom timeline over ten days. Panel B: Symptomatic treatment algorithm showing interventions matched to specific symptoms including congestion, rhinorrhea, sore throat, cough, and fever with recommended agents. Panel C: Chart depicting ineffective treatments for viral URI including antibiotics, vitamin C after onset, and inconsistent evidence for zinc and echinacea with supporting evidence summaries. Panel D: Red flag identification flowchart showing high fever, severe facial pain, neck stiffness, respiratory distress, and prolonged duration with corresponding concerns and actions.</image>

II. Pharyngitis

Pharyngitis presents a common diagnostic challenge requiring differentiation between viral and bacterial etiologies to guide appropriate treatment decisions. Viral pharyngitis accounts for seventy to eighty percent of cases and is caused by numerous pathogens including rhinoviruses, adenoviruses, Epstein-Barr virus, and influenza. Group A streptococcus causes ten to twenty percent of pharyngitis cases in adults and up to thirty percent in children, representing the primary bacterial pathogen of concern due to its association with rheumatic fever and suppurative complications. Other bacterial causes including groups C and G streptococci, Fusobacterium, and Arcanobacterium are uncommon and generally do not require antibiotic treatment. Accurate diagnosis enables appropriate treatment of streptococcal pharyngitis while avoiding unnecessary antibiotics for viral illness.

The Centor criteria and modified Centor score provide clinical prediction tools for estimating the probability of group A streptococcal pharyngitis. Classic Centor criteria award one point each for tonsillar exudates, tender anterior cervical lymphadenopathy, history or presence of fever, and absence of cough. The modified score adds age modification, adding one point for ages three through fourteen, no modification for ages fifteen through forty-four, and subtracting one point for ages forty-five and above. Interpretation of scores guides testing and treatment decisions, with scores of zero to one indicating low probability not warranting testing or treatment, scores of two to three indicating moderate probability warranting rapid strep testing with treatment if positive, and scores of four or higher indicating high probability where empiric treatment may be reasonable though testing remains preferred.

Management of confirmed or highly probable group A streptococcal pharyngitis requires antibiotic treatment to prevent rheumatic fever, reduce suppurative complications, decrease symptom duration, and limit transmission. Penicillin remains the first-line treatment given its narrow spectrum, established efficacy, low cost, and lack of documented resistance, with dosing options including penicillin V five hundred milligrams twice daily or two hundred fifty milligrams four times daily for ten days. Amoxicillin provides an alternative with more palatable formulations, particularly for children, at doses of five hundred milligrams twice daily or one thousand milligrams once daily for ten days. Patients with penicillin allergy may receive azithromycin as a five-day course or cephalexin if the allergy is not severe. The primary treatment goal is prevention of rheumatic fever, which requires completion of the full antibiotic course even after symptom resolution.

Supportive care for pharyngitis provides symptom relief regardless of etiology and should be emphasized alongside antibiotic treatment when indicated. Analgesics including acetaminophen and nonsteroidal anti-inflammatory drugs reduce pain and fever effectively. Topical measures including salt water gargles, throat lozenges, and anesthetic sprays provide local relief. Adequate hydration and soft foods ease swallowing discomfort. Patients should be informed that symptomatic improvement begins within one to two days of antibiotic initiation for streptococcal pharyngitis, while viral pharyngitis resolves over approximately one week regardless of treatment. Return precautions should address worsening symptoms, difficulty swallowing or breathing, or inability to maintain hydration, which may indicate peritonsillar abscess or other complications.

<image>Panel A: Pie chart showing etiology of pharyngitis with viral causes at seventy to eighty percent, group A streptococcus at ten to twenty percent, and other bacterial at less than five percent with key pathogens listed. Panel B: Modified Centor score calculation showing clinical criteria with point values and age modifications alongside probability estimates and recommended actions for each score range. Panel C: Streptococcal pharyngitis treatment algorithm showing first-line penicillin or amoxicillin with dosing, penicillin allergy alternatives, and treatment duration with goals of therapy. Panel D: Supportive care options for pharyngitis regardless of etiology including analgesics, topical treatments, hydration, and dietary modifications with return precaution indicators.</image>

III. Acute Sinusitis

Acute sinusitis presents diagnostic challenges in distinguishing viral from bacterial etiology and selecting patients who may benefit from antibiotic treatment. The clinical syndrome involves purulent nasal discharge accompanied by nasal obstruction or facial pain and pressure, with symptom duration of less than four weeks defining acute presentation. The vast majority of acute sinusitis cases are viral, representing extension of upper respiratory infection into the paranasal sinuses with inflammation and mucus production. Bacterial superinfection occurs in only a small percentage of cases, and even bacterial sinusitis often resolves spontaneously without antibiotic treatment. This natural history requires careful patient selection for antibiotic therapy to maximize benefit while minimizing unnecessary treatment.

Clinical criteria distinguish bacterial from viral sinusitis based on symptom pattern rather than symptom presence, as the same symptoms occur in both conditions. Persistent symptoms lasting ten days or longer without improvement suggest bacterial etiology, as viral illness typically shows improvement by this timeframe. Severe symptoms presenting with high fever exceeding one hundred two degrees Fahrenheit and purulent nasal discharge persisting for three to four consecutive days from illness onset indicate bacterial infection. Double worsening, characterized by initial improvement followed by new fever, worsening headache, or increased nasal discharge, suggests secondary bacterial infection. Meeting any of these three patterns provides reasonable indication for antibiotic treatment, while absence of all three suggests viral etiology warranting supportive care alone.

Treatment of bacterial sinusitis should employ first-line antibiotics with appropriate spectrum and duration. Amoxicillin-clavulanate provides first-line therapy at standard dosing of five hundred milligrams three times daily or eight hundred seventy-five milligrams twice daily for five to seven days, with the clavulanate component addressing beta-lactamase-producing organisms increasingly encountered in sinusitis. Patients with penicillin allergy may receive doxycycline or a respiratory fluoroquinolone, though the latter should be reserved for patients without alternative options given concerns about adverse effects and resistance. Treatment duration of five to seven days is sufficient for uncomplicated cases, representing a shift from historical ten to fourteen day courses. Failure to improve within seventy-two hours of antibiotic initiation should prompt reassessment and consideration of alternative diagnosis or antibiotic change.

Adjunctive treatments provide symptomatic relief and may accelerate resolution regardless of etiology. Nasal saline irrigation using commercially available squeeze bottles or neti pots helps clear secretions and soothe inflamed mucosa with minimal risk. Intranasal corticosteroids reduce inflammation and may modestly accelerate symptom resolution, though evidence for monotherapy in acute sinusitis is limited. Oral decongestants and topical decongestants provide temporary relief of nasal congestion. Analgesics address facial pain and headache. Imaging with computed tomography is not recommended for uncomplicated acute sinusitis, as abnormal findings are nearly universal during viral upper respiratory infection and do not distinguish viral from bacterial etiology. CT should be reserved for suspected complications such as orbital involvement or intracranial extension, or for evaluation of recurrent or chronic sinusitis.

<image>Panel A: Clinical presentation comparison showing symptoms shared by viral and bacterial sinusitis including purulent discharge, nasal obstruction, and facial pain with notation that symptoms alone do not distinguish etiology. Panel B: Bacterial sinusitis diagnostic criteria showing three patterns of persistent symptoms beyond ten days, severe symptoms with high fever, and double worsening with management implications. Panel C: Antibiotic treatment algorithm for bacterial sinusitis showing first-line amoxicillin-clavulanate, penicillin allergy alternatives, treatment duration, and failure assessment at seventy-two hours. Panel D: Adjunctive treatment options including nasal saline irrigation, intranasal corticosteroids, decongestants, and analgesics with imaging indications limited to suspected complications.</image>

IV. Acute Bronchitis

Acute bronchitis represents one of the most common conditions seen in primary care and one of the most frequently over-treated with antibiotics despite overwhelming evidence that antibiotics provide no benefit. The condition is caused by viral infection in over ninety percent of cases, with the same pathogens responsible for upper respiratory infections extending to cause inflammation of the bronchial tree. The hallmark symptom is cough, which may be productive or dry and typically persists for two to three weeks, often longer than patients expect. Low-grade fever may occur early in the illness course, but high persistent fever suggests alternative diagnosis. Understanding the viral etiology and natural history of prolonged cough is essential for providing effective patient education and avoiding unnecessary antibiotic prescribing.

Distinguishing acute bronchitis from pneumonia represents the key diagnostic consideration, as pneumonia may require antibiotic treatment while bronchitis does not. Concerning features for pneumonia include fever exceeding one hundred point four degrees Fahrenheit that persists beyond the first few days, tachypnea with respiratory rate exceeding twenty breaths per minute, abnormal lung examination findings suggesting consolidation such as focal crackles, dullness to percussion, or egophony, and hypoxia with oxygen saturation below ninety-five percent. Elderly patients and those with significant comorbidities warrant lower threshold for chest radiography and further evaluation. The absence of these concerning features in an otherwise healthy adult supports diagnosis of acute bronchitis without need for chest radiography or other testing.

Management of acute bronchitis centers on symptomatic treatment and patient education, with explicit avoidance of antibiotic prescribing. Multiple systematic reviews and meta-analyses have demonstrated that antibiotics provide no meaningful benefit for acute bronchitis in healthy adults, with at most minimal reduction in cough duration that is outweighed by side effects and resistance concerns. Cough suppressants including dextromethorphan provide modest benefit and may be used for symptomatic relief. Bronchodilators are not routinely recommended but may be considered if wheezing is present, particularly in patients with underlying asthma or chronic obstructive pulmonary disease. Honey provides safe and modestly effective cough relief for patients over one year of age. Expectant management with reassurance that cough may persist for three weeks is often the most important intervention.

Effective patient communication addresses expectations and reduces demand for unnecessary antibiotics. Explaining the viral cause using patient-friendly language helps patients understand why antibiotics will not help, such as noting that the infection is caused by a virus similar to the common cold and that antibiotics only work against bacteria. Setting realistic expectations about symptom duration is crucial, as many patients expect cough to resolve within one to two weeks and become concerned when it persists. Offering symptomatic treatment alternatives demonstrates responsiveness to patient concerns even while withholding antibiotics. Providing clear return precautions empowers patients to seek reassessment if concerning symptoms develop, such as new fever after initial improvement, worsening shortness of breath, or failure to improve after three weeks. This communication approach maintains patient trust while practicing appropriate antibiotic stewardship.

<image>Panel A: Etiology diagram showing viral causes of acute bronchitis including rhinovirus, influenza, and coronavirus with symptom timeline depicting cough duration of two to three weeks. Panel B: Decision algorithm for distinguishing bronchitis from pneumonia using presence or absence of persistent fever, tachypnea, abnormal lung findings, and hypoxia with management pathways. Panel C: Treatment approach showing symptomatic options including cough suppressants, honey, and conditional bronchodilator use alongside explicit indication that antibiotics are not recommended with supporting evidence. Panel D: Patient communication framework showing explanation of viral cause, expectation setting for symptom duration, alternative treatment offerings, and specific return precaution instructions.</image>

V. Urinary Tract Infections

Urinary tract infections represent common acute conditions with different management approaches depending on patient characteristics, infection location, and presence of complicating factors. Uncomplicated cystitis refers to bladder infection in healthy, non-pregnant women without structural or functional abnormalities of the urinary tract, representing the most common and straightforward presentation. Complicated urinary tract infections occur in men, pregnant women, patients with structural abnormalities, catheterized patients, or those with other complicating factors that increase risk of treatment failure or serious complications. Pyelonephritis involves upper urinary tract infection with kidney involvement, characterized by systemic symptoms and requiring different treatment approaches. Accurate classification guides appropriate diagnostic testing and treatment selection.

Diagnosis of uncomplicated cystitis relies primarily on clinical presentation, with classic symptoms including dysuria, urinary frequency, and urgency. Urinalysis demonstrating pyuria and bacteriuria supports the diagnosis but is not required when symptoms are classic, as empiric treatment based on symptoms alone is both safe and cost-effective in this population. Urine culture is not routinely necessary for uncomplicated cystitis, as the causative organism and susceptibility pattern are predictable. However, urine culture should be obtained for complicated urinary tract infections, pyelonephritis, recurrent infections, treatment failures, and when resistance is suspected based on prior culture results or recent antibiotic exposure. The presence of vaginal symptoms such as discharge or irritation suggests alternative diagnosis including vaginitis or sexually transmitted infection and warrants different evaluation.

Treatment of uncomplicated cystitis employs first-line antibiotics selected for efficacy, safety, and minimal resistance impact. Nitrofurantoin monohydrate macrocrystals one hundred milligrams twice daily for five days provides excellent first-line therapy with narrow spectrum that minimizes collateral damage to normal flora and resistance development. Trimethoprim-sulfamethoxazole one sixty over eight hundred milligrams twice daily for three days offers an alternative when local resistance rates are below twenty percent. Fosfomycin three grams as a single dose provides convenient option though with slightly lower efficacy. Fluoroquinolones should be avoided for uncomplicated cystitis given concerns about adverse effects including tendinopathy, neuropathy, and central nervous system effects, reserving these agents for situations without alternative options. Beta-lactam antibiotics represent second-line options with somewhat lower efficacy.

Pyelonephritis and urinary tract infections in special populations require modified approaches reflecting increased severity and complication risk. Pyelonephritis presents with fever, flank pain, and costovertebral angle tenderness, with or without lower tract symptoms. Outpatient treatment with fluoroquinolone for five to seven days or trimethoprim-sulfamethoxazole for fourteen days is appropriate for patients who are not severely ill, can tolerate oral intake, and have reliable follow-up. Hospitalization is indicated for severe illness, inability to tolerate oral medications, pregnancy, or suspected urinary obstruction. Urinary tract infection during pregnancy requires culture-guided treatment and test of cure, with caution regarding medication safety including avoidance of trimethoprim-sulfamethoxazole in first trimester and near term and avoidance of nitrofurantoin near term. Men with urinary tract infection should be evaluated for complicating factors and treated with longer antibiotic courses, typically seven to fourteen days.

<image>Panel A: Classification diagram showing uncomplicated cystitis criteria in healthy non-pregnant women versus complicated UTI criteria including male sex, pregnancy, structural abnormalities, and catheterization with pyelonephritis as upper tract involvement. Panel B: Diagnostic approach for uncomplicated cystitis showing clinical symptoms sufficient for diagnosis, urinalysis supportive but not required, and situations requiring urine culture. Panel C: First-line antibiotic treatment options for uncomplicated cystitis showing nitrofurantoin, trimethoprim-sulfamethoxazole, and fosfomycin with dosing, duration, and fluoroquinolone avoidance rationale. Panel D: Pyelonephritis management showing presentation features, outpatient versus inpatient criteria, treatment regimens, and special population considerations for pregnancy and male patients.</image>

VI. Acute Low Back Pain

Acute low back pain affects the vast majority of adults at some point and represents one of the most frequent reasons for primary care visits. The first priority in evaluation is identification of red flags suggesting serious underlying pathology that requires urgent evaluation and treatment. Saddle anesthesia and urinary retention suggest cauda equina syndrome requiring emergent surgical evaluation. Progressive motor weakness, particularly bilateral, raises concern for cord compression or cauda equina. History of cancer, unexplained weight loss, or failure to improve with conservative treatment should prompt evaluation for spinal metastases. Fever combined with back pain, particularly in patients with history of intravenous drug use, suggests spinal infection. Significant trauma or osteoporosis with even minor trauma raises concern for fracture. The presence of any red flag warrants immediate imaging and possible emergent referral.

In the absence of red flags, acute low back pain is classified as nonspecific in the vast majority of cases, meaning no identifiable anatomic cause can be determined through history, examination, or imaging. This classification is not a failure of diagnosis but rather recognition that pain often arises from structures that cannot be definitively identified and that prognosis is excellent regardless of the specific pain generator. Radiculopathy with dermatomal pain distribution and nerve root signs represents a distinct category with somewhat different prognosis but still generally favorable outcomes with conservative treatment. History and physical examination should assess pain characteristics including location, radiation, timing, and aggravating and relieving factors. Neurological examination includes assessment of motor strength in key myotomes, sensory examination, deep tendon reflexes, and straight leg raise testing for radiculopathy.

Imaging for acute low back pain should be reserved for patients with red flags and is not indicated for nonspecific low back pain regardless of severity. Multiple studies have demonstrated that routine imaging does not improve outcomes and may cause harm through identification of incidental findings, increased medicalization, and higher rates of surgery without corresponding benefit. The ubiquity of degenerative findings on imaging in asymptomatic individuals means that positive findings frequently represent incidental abnormalities rather than pain causes, leading to inappropriate treatment targeting these findings. If symptoms persist beyond six weeks despite conservative treatment, imaging may be considered to evaluate for structural abnormalities that might benefit from intervention. MRI represents the imaging modality of choice when neurological deficit is present or infection or malignancy is suspected, while plain radiography suffices for fracture evaluation.

Treatment of acute nonspecific low back pain emphasizes activity, simple analgesics, and reassurance about favorable prognosis. The most important intervention is encouragement to stay active and avoid bed rest, as prolonged rest delays recovery and increases risk of chronic pain development. Nonsteroidal anti-inflammatory drugs provide first-line pharmacological therapy with evidence of modest benefit. Acetaminophen represents an alternative for patients who cannot tolerate NSAIDs, though evidence of efficacy specifically for back pain is limited. Superficial heat provides short-term relief without significant risk. Muscle relaxants may be considered for short-term use when muscle spasm is prominent, though sedation limits utility. Opioids should be avoided for routine acute low back pain given lack of superior efficacy, substantial risks, and potential to complicate recovery. Physical therapy referral is appropriate for patients not improving with initial management.

<image>Panel A: Red flag identification checklist showing cauda equina symptoms, progressive weakness, cancer history, fever with spinal tenderness, and trauma with corresponding serious conditions and required urgent actions. Panel B: Classification framework showing nonspecific back pain as majority category without identifiable structural cause, radiculopathy with nerve root signs, and serious pathology identified by red flags. Panel C: Imaging indications showing red flags require immediate imaging, nonspecific back pain does not require imaging regardless of severity, and consideration of imaging after six weeks without improvement with explanation of incidental finding concerns. Panel D: First-line treatment approach showing stay active as most important recommendation, NSAIDs for analgesia, heat for symptomatic relief, and explicit avoidance of bed rest and opioids with prognosis information.</image>

VII. Headache in Primary Care

Headache evaluation in primary care requires efficient differentiation between common primary headache disorders and less common but serious secondary causes requiring urgent intervention. Primary headache disorders including tension-type headache, migraine, and cluster headache account for the vast majority of headache presentations and are diagnosed based on clinical features without need for diagnostic testing. Secondary headaches result from underlying pathology including subarachnoid hemorrhage, brain tumor, meningitis, giant cell arteritis, and numerous other conditions that require identification and treatment of the underlying cause. Tension-type headache represents the most common headache disorder, while migraine is the most common reason for headache-related medical visits due to its greater severity and disability.

Red flag features during headache evaluation identify patients requiring urgent evaluation for potentially life-threatening conditions. Sudden onset headache reaching maximum intensity within seconds to minutes, often described as thunderclap headache, raises concern for subarachnoid hemorrhage and requires emergent evaluation. Characterization as the worst headache of life, even without thunderclap onset, also suggests subarachnoid hemorrhage. Fever with neck stiffness indicates possible meningitis requiring lumbar puncture and empiric antibiotic treatment. New onset headache after age fifty raises concern for giant cell arteritis and intracranial pathology. Focal neurological deficits or altered mental status suggest structural lesion or other serious pathology. Papilledema on fundoscopic examination indicates elevated intracranial pressure. Progressive worsening over days to weeks without prior similar headaches warrants imaging to evaluate for mass lesion.

Tension-type headache is characterized by bilateral location, pressing or tightening quality, mild to moderate intensity, and absence of features typical of migraine. Pain does not worsen with routine physical activity and is not accompanied by nausea, vomiting, or significant photophobia or phonophobia. Episodes last from thirty minutes to seven days. Treatment relies on simple analgesics including acetaminophen, aspirin, or nonsteroidal anti-inflammatory drugs, with caution to limit use to avoid medication overuse headache, which occurs with analgesic use exceeding ten to fifteen days per month. Patients with frequent tension-type headache may benefit from prophylactic treatment with tricyclic antidepressants and nonpharmacological approaches including stress management, sleep hygiene, and regular exercise.

Migraine is characterized by recurrent headaches lasting four to seventy-two hours with unilateral location, pulsating quality, moderate to severe intensity, and aggravation by routine physical activity. Associated features include nausea, vomiting, photophobia, and phonophobia, with at least some of these present during most attacks. Approximately one-third of migraine patients experience aura, typically visual disturbance preceding headache by five to sixty minutes. Acute treatment includes nonsteroidal anti-inflammatory drugs for mild to moderate attacks and triptans for moderate to severe attacks or those not responding to NSAIDs. Prophylactic treatment should be considered for patients experiencing four or more headache days per month, with options including beta-blockers, antidepressants, antiepileptic drugs, and CGRP monoclonal antibodies for refractory cases. Patient education about trigger identification and lifestyle modification supports pharmacological management.

<image>Panel A: Headache classification showing primary headache disorders including tension-type, migraine, and cluster as majority of presentations versus secondary causes requiring identification of underlying pathology. Panel B: Red flag identification showing thunderclap onset, worst headache ever, fever with neck stiffness, age over fifty new onset, neurological deficits, and papilledema with corresponding serious conditions. Panel C: Tension-type headache diagnostic criteria showing bilateral pressing quality, mild to moderate intensity, no worsening with activity, and absence of migraine features with treatment approach using simple analgesics and medication overuse caution. Panel D: Migraine characteristics showing unilateral pulsating quality, moderate to severe intensity, activity aggravation, and associated symptoms with acute treatment options and prophylaxis indications.</image>

VIII. Skin and Soft Tissue Infections

Skin and soft tissue infections range from minor conditions manageable with simple interventions to serious infections requiring hospitalization and surgical management. Cellulitis represents infection of the dermis and subcutaneous tissue characterized by spreading erythema, warmth, and tenderness without purulence or underlying collection. Streptococcus pyogenes causes the majority of non-purulent cellulitis cases, with Staphylococcus aureus contributing in a minority. The spreading nature of cellulitis distinguishes it from localized abscess formation, and the absence of fluctuance suggests that incision and drainage will not be beneficial. Cutaneous abscess represents a localized collection of pus within the dermis or subcutaneous tissue, often caused by methicillin-resistant Staphylococcus aureus in community settings, requiring drainage as primary treatment.

Treatment of uncomplicated cellulitis without purulence or underlying abscess relies on antibiotic therapy targeting streptococcal organisms. First-line options include cephalexin five hundred milligrams four times daily or dicloxacillin five hundred milligrams four times daily for five to seven days. Penicillin VK represents an alternative specifically targeting streptococci. The addition of methicillin-resistant Staphylococcus aureus coverage with trimethoprim-sulfamethoxazole or doxycycline should be considered when purulence is present, when prior MRSA infection or colonization is documented, when local MRSA prevalence is high, or when initial treatment fails. Elevation of the affected extremity, when applicable, promotes drainage and reduces swelling. Marking the border of erythema enables objective assessment of treatment response, with failure to improve or continued spread after forty-eight to seventy-two hours indicating need for treatment modification or hospitalization.

Cutaneous abscess requires incision and drainage as the primary and often sole necessary treatment. Antibiotics are not required for small, uncomplicated abscesses in healthy patients when drainage is adequate, as multiple studies have shown no benefit from adjunctive antibiotics in this setting. Antibiotic therapy should be added for larger abscesses, presence of surrounding cellulitis extending beyond the abscess margin, multiple abscesses, immunocompromise, or systemic signs of infection. When antibiotics are indicated, trimethoprim-sulfamethoxazole or doxycycline provides coverage for community-acquired MRSA that commonly causes these infections. The drainage procedure involves adequate anesthesia, incision over the fluctuant area, expression of purulent material, exploration to break up loculations, irrigation with saline, and packing for larger cavities to maintain drainage. Follow-up within twenty-four to forty-eight hours enables packing change and assessment of healing.

Certain clinical features warrant hospitalization for skin and soft tissue infections rather than outpatient management. Signs of sepsis including fever, tachycardia, hypotension, or altered mental status indicate serious systemic infection requiring intravenous antibiotics and close monitoring. Rapidly spreading infection despite oral antibiotics suggests aggressive organism or inadequate treatment. Deep space infections, necrotizing fasciitis, or infection overlying hardware or prostheses require surgical consultation and often operative intervention. Facial cellulitis carries risk of spread to cavernous sinus or other dangerous structures. Orbital cellulitis manifests as proptosis, ophthalmoplegia, or vision changes and requires emergent evaluation. Immunocompromised patients may require more aggressive management given reduced ability to contain infection. When hospitalization is indicated, blood cultures should be obtained and broad-spectrum intravenous antibiotics initiated pending culture results.

<image>Panel A: Clinical differentiation between cellulitis showing spreading erythema without purulence and abscess showing localized fluctuant collection, with predominant organisms for each and primary treatment approach. Panel B: Cellulitis treatment algorithm showing first-line oral antibiotics for streptococcal coverage, indications for MRSA coverage addition, and supportive measures including elevation and border marking for response assessment. Panel C: Abscess management showing incision and drainage as primary treatment, criteria for adding antibiotics versus drainage alone, antibiotic selection when indicated, and drainage procedure steps. Panel D: Hospitalization criteria for skin and soft tissue infections including sepsis signs, rapidly spreading infection, deep space involvement, facial or orbital location, and immunocompromise with initial management approach.</image>

IX. Acute Diarrhea

Acute diarrhea lasting less than fourteen days represents a common complaint requiring assessment of severity, identification of patients requiring testing, and appropriate supportive management. Initial assessment determines duration with acute defined as less than fourteen days, persistent as fourteen to thirty days, and chronic as greater than thirty days. Stool character as watery versus bloody provides important diagnostic information, with bloody diarrhea suggesting invasive bacterial pathogens or inflammatory conditions. Associated symptoms including fever, abdominal pain, and signs of dehydration guide management decisions. Exposure history including recent food intake, travel, sick contacts, and healthcare or antibiotic exposure helps identify likely causes and appropriate testing strategies.

Most acute diarrhea is caused by viral pathogens and resolves spontaneously without specific treatment or diagnostic testing. Norovirus represents the most common cause of acute gastroenteritis in adults, with typical presentation of watery diarrhea, nausea, vomiting, and low-grade fever lasting one to three days. Campylobacter and Salmonella constitute the most common bacterial causes of community-acquired diarrhea, typically causing more prolonged symptoms with fever and sometimes bloody stools. Traveler's diarrhea is most commonly caused by enterotoxigenic Escherichia coli and typically resolves within a few days. Clostridioides difficile infection should be suspected in patients with recent healthcare exposure or antibiotic use within the preceding eight weeks, presenting with watery diarrhea, cramping, and sometimes fever.

Diagnostic testing is not required for most cases of acute diarrhea but should be obtained in specific circumstances. Stool culture is indicated for bloody diarrhea, severe or prolonged symptoms, fever, or when public health investigation is needed such as for suspected foodborne outbreak. Clostridioides difficile testing should be performed for patients with diarrhea following antibiotic exposure or recent hospitalization. Ova and parasite examination is indicated for persistent diarrhea, travel to endemic areas, or suspected Giardia or Cryptosporidium exposure. Immunocompromised patients warrant comprehensive testing given expanded differential diagnosis including opportunistic pathogens. Testing should also be considered for patients in high-risk occupations such as food handlers or healthcare workers where infection may have public health implications.

Treatment of acute diarrhea emphasizes hydration as the cornerstone of management, with specific therapy reserved for selected situations. Oral rehydration with commercially available solutions or homemade alternatives maintains fluid and electrolyte balance for most patients, with intravenous fluid indicated for severe dehydration or inability to tolerate oral intake. Continued eating as tolerated promotes mucosal recovery, with no evidence supporting dietary restriction beyond avoiding foods that exacerbate symptoms. Antibiotics are not routinely indicated for acute diarrhea given the viral etiology of most cases and self-limited nature of many bacterial infections. Empiric antibiotics with fluoroquinolone or azithromycin may be considered for traveler's diarrhea, severe symptoms, or when specific bacterial pathogens are suspected, but should be avoided when Shiga toxin-producing Escherichia coli is suspected due to risk of hemolytic uremic syndrome. Antimotility agents such as loperamide may provide symptomatic relief for watery diarrhea but should be avoided in bloody or febrile diarrhea.

<image>Panel A: Initial assessment framework for acute diarrhea showing duration classification, stool character as watery versus bloody, associated symptoms, and relevant exposure history including food, travel, contacts, and healthcare. Panel B: Common causes of acute diarrhea showing viral pathogens including norovirus as most common, bacterial pathogens including Campylobacter and Salmonella, traveler's diarrhea organisms, and Clostridioides difficile with risk factors. Panel C: Indications for diagnostic testing showing stool culture for bloody or severe diarrhea, C. difficile testing for antibiotic exposure, ova and parasites for travel or persistent symptoms, and comprehensive testing for immunocompromised patients. Panel D: Treatment approach showing oral rehydration as cornerstone, continued eating as tolerated, selective antibiotic use with indications and avoidance of STEC concern, and antimotility agent limitations.</image>

X. Antibiotic Stewardship

Antibiotic stewardship encompasses systematic efforts to optimize antibiotic use through selection of the right drug, at the right dose, for the right duration, while avoiding unnecessary antibiotic prescribing. The imperative for stewardship arises from the public health threat of antimicrobial resistance, which has been identified by major health organizations as one of the most significant challenges facing modern medicine. Inappropriate antibiotic use drives resistance development by eliminating susceptible organisms and allowing resistant strains to proliferate. Primary care settings account for the majority of antibiotic prescriptions, with a substantial proportion directed toward conditions that do not benefit from antibiotic treatment, making stewardship in these settings essential for addressing resistance at the population level.

Common situations of antibiotic overuse in primary care have been well characterized and represent priority targets for stewardship intervention. Viral upper respiratory infections including the common cold, acute bronchitis, and viral pharyngitis account for the largest proportion of inappropriate antibiotic prescribing, as these conditions are caused by viruses against which antibiotics have no activity. Acute sinusitis is frequently treated with antibiotics despite the viral etiology of most cases and the self-limited nature of even many bacterial cases. Asymptomatic bacteriuria in non-pregnant adults, particularly elderly individuals, is commonly treated despite evidence that treatment provides no benefit and may cause harm. Viral gastroenteritis and non-specific diarrhea rarely benefit from antibiotic treatment. Skin and soft tissue infections may receive broader-spectrum or longer-duration treatment than necessary.

Effective patient communication is essential for successful stewardship, as patient expectations and satisfaction concerns often drive inappropriate prescribing. Explaining the cause of illness in patient-friendly terms helps patients understand why antibiotics will not help, avoiding medical jargon while conveying that viral infections do not respond to antibiotics. Setting realistic expectations about symptom duration reduces anxiety about prolonged symptoms that might otherwise drive repeat visits and antibiotic requests. Offering symptomatic treatment alternatives demonstrates that clinicians are responsive to patient concerns even while withholding antibiotics. Providing specific safety-net instructions empowers patients to return if warning signs develop while providing reassurance about the expected course. The delayed prescription strategy, where a prescription is provided with instructions to fill only if symptoms worsen or fail to improve after a specified interval, represents an option for selected patients, though immediate prescribing avoidance is preferred.

The consequences of antibiotic overuse extend beyond the theoretical concern of future resistance to immediate harms affecting individual patients. Adverse drug reactions including gastrointestinal symptoms, allergic reactions, and drug interactions occur frequently with antibiotic exposure. Clostridioides difficile infection, which may be severe and difficult to treat, represents a direct consequence of antibiotic-mediated disruption of normal gut flora. Cost to patients and the healthcare system from unnecessary medication and associated visits is not trivial. At the population level, resistance development threatens the effectiveness of antibiotics for treating serious infections, with some organisms already demonstrating resistance to nearly all available agents. Communicating both individual and societal consequences helps patients understand the importance of appropriate antibiotic use beyond their immediate illness.

<image>Panel A: Antibiotic stewardship principles showing selection of right drug, dose, and duration with avoidance of unnecessary prescribing, supported by the context of antimicrobial resistance as a major public health threat. Panel B: Common inappropriate antibiotic use targets in primary care showing viral URI, acute bronchitis, viral pharyngitis, most acute sinusitis, asymptomatic bacteriuria, and viral gastroenteritis with better management approaches. Panel C: Patient communication strategies for stewardship showing explanation of illness cause, expectation setting for duration, symptomatic alternatives, safety-net instructions, and delayed prescription option with preferred approaches. Panel D: Consequences of antibiotic overuse showing individual harms including adverse reactions and C. difficile infection, costs to patients and system, and population-level resistance development threatening future treatment effectiveness.</image>

Summary

• Viral upper respiratory infections require supportive care only with no benefit from antibiotics, vitamin C, or consistently from zinc or echinacea
• Group A streptococcal pharyngitis is diagnosed using Centor criteria to guide testing and treated with penicillin or amoxicillin for ten days
• Acute bacterial sinusitis is suggested by symptoms persisting ten days without improvement, severe onset, or double worsening pattern
• Acute bronchitis is viral in over ninety percent of cases and antibiotics are not indicated in healthy adults regardless of cough severity or duration
• Uncomplicated cystitis in healthy women is treated with nitrofurantoin for five days as first-line, avoiding fluoroquinolones for this indication
• Acute low back pain evaluation prioritizes red flag identification, with imaging not indicated for nonspecific back pain
• Headache red flags include thunderclap onset, worst headache ever, fever with stiffness, new onset after age fifty, and neurological deficits
• Cellulitis without purulence is treated with streptococcal coverage using cephalexin, while abscess requires incision and drainage as primary treatment
• Acute diarrhea management centers on rehydration with testing reserved for bloody, severe, or persistent cases and antibiotic exposure
• Antibiotic stewardship requires effective communication explaining viral illness, setting expectations, and offering symptomatic alternatives

Key Terms

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