30.2 Acute Bronchitis & Lower Respiratory Tract Infections

ABFM Family Medicine Certification Study Guide Exam

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1 Chapter 1: Exam Structure, Blueprint & Clinical Decision-Making

1.1 Exam Blueprint, FMCLA vs. One-Day Exam & Board Scoring 1.2 Clinical Reasoning, Test-Taking Strategy & Ambiguity Management 1.3 Evidence-Based Medicine & Clinical Practice Guidelines in Primary Care

2 Chapter 2: Healthcare Systems, Practice Management & Quality

2.1 Practice Management, Billing, Coding & Documentation 2.2 Quality Improvement, Patient Safety & Diagnostic Stewardship 2.3 Interprofessional Team-Based Care & Care Coordination

3 Chapter 3: Ethics, Law, Biostatistics & Health Equity

3.1 Medical Ethics, Informed Consent & Surrogate Decision-Making 3.2 Biostatistics, Clinical Epidemiology & Diagnostic Test Interpretation 3.3 Social Determinants of Health, Health Equity & Cultural Humility 3.4 Physician Wellness, Burnout Prevention & Professionalism

4 Chapter 4: Lifestyle Counseling & Behavior Change

4.1 Alcohol Use Screening & Brief Intervention 4.2 Illicit Drug & Cannabis Counseling 4.3 Tobacco & Vaping Cessation Counseling

5 Chapter 5: Nutrition, Physical Activity & Chronic Disease Prevention

5.1 Dietary Counseling for Obesity & Chronic Disease Prevention 5.2 Exercise Prescription & Physical Activity Counseling 5.3 Genetic Risk Assessment & Family History Counseling

6 Chapter 6: Routine Adult Immunizations

6.1 ACIP Adult Respiratory Vaccines: Influenza, COVID-19, RSV & Pneumococcal 6.2 ACIP Adult Non-Respiratory Vaccines: Tdap, Shingrix, HPV & Hep B 6.3 Immunizations in Special Populations: Pregnancy, Asplenia & Immunocompromise

7 Chapter 7: Pediatric Health Maintenance & Surveillance

7.1 Newborn Examination & Early Postnatal Care 7.2 Well-Child Care, Developmental Surveillance & Milestones 7.3 Pediatric & Adolescent Screening: Vision, Hearing, Anemia & Lead 7.4 Pediatric Oral Health, Dental Screening & Fluoride

8 Chapter 8: Behavioral Health & Safety Screening

8.1 Primary Care Depression, Anxiety & Behavioral Health Screening 8.2 Domestic Violence, Intimate Partner Violence & Firearm Safety 8.3 Occupational Health & Recreational Safety Counseling

9 Chapter 9: Adult Preventive Screening: Cardiovascular & Metabolic

9.1 Cardiovascular Disease & Hypertension Screening 9.2 Type 2 Diabetes Screening & Prediabetes Risk Stratification 9.3 Abdominal Aortic Aneurysm & Osteoporosis Screening

10 Chapter 10: Adult Cancer Screening: Breast & Gynecologic

10.1 Breast Cancer Screening & Risk-Assessment 10.2 Cervical Cancer Screening & ASCCP Algorithms 10.3 Skin Cancer Clinical Assessment & Counseling

11 Chapter 11: Adult Cancer Screening: Colorectal, Lung & Prostate

11.1 Colorectal Cancer Screening Modalities & Intervals 11.2 Lung Cancer Screening with Low-Dose CT 11.3 Prostate Cancer Screening & Shared Decision-Making

12 Chapter 12: Sexual Health, Infectious Disease Screening & Contraception

12.1 Sexual Health Counseling & Risk-Reduction Strategies 12.2 STI Screening: Chlamydia, Gonorrhea, Syphilis & Trichomoniasis 12.3 Bloodborne Infectious Disease Screening: HIV & Hepatitis C

13 Chapter 13: Reproductive Life Planning, Lactation & Preoperative Care

13.1 Preconception Planning & Comprehensive Contraception Management 13.2 Lactation Support & Breastfeeding Counseling 13.3 Preoperative Medical Evaluation & Pre-Participation Sports Exam

14 Chapter 14: Emergent Cardiovascular Conditions

14.1 Acute Coronary Syndromes & Myocardial Infarction 14.2 Acute Chest Pain Risk Stratification & Triage 14.3 Acute or Critical Valvular Heart Emergencies

15 Chapter 15: Cardiac Arrhythmias, Heart Failure & Hypertensive Crises

15.1 Acute Atrial & Ventricular Arrhythmias 15.2 Acute Decompensated Heart Failure & Cardiogenic Shock 15.3 Hypertensive Emergency & Urgency Management

16 Chapter 16: Vascular & Thromboembolic Emergencies

16.1 Pulmonary Embolism & Deep Vein Thrombosis 16.2 Acute Aortic Syndromes & Peripheral Vascular Emergencies 16.3 Critical Limb Ischemia & Acute Arterial Occlusion

17 Chapter 17: Neurologic Emergencies: Stroke & Altered Consciousness

17.1 Acute Ischemic Stroke & Intracranial Hemorrhage 17.2 Syncope Evaluation & Status Epilepticus 17.3 Acute Delirium, Encephalopathy & Severe Confusion

18 Chapter 18: Neurologic Trauma & Acute Cranial Emergencies

18.1 Concussion, Moderate-to-Severe TBI & Intracranial Injury 18.2 Thunderclap & Acute Severe Secondary Headaches 18.3 Acute Ophthalmologic Emergencies

19 Chapter 19: Acute Abdominal, Pelvic & Gastrointestinal Emergencies

19.1 Acute Abdominal & Pelvic Pain Triage 19.2 Upper & Lower Gastrointestinal Bleeding 19.3 Acute Hepatic Failure, Cholangitis & Severe Jaundice

20 Chapter 20: Acute Pulmonary & Airway Emergencies

20.1 Acute Hypoxic Respiratory Failure & ARDS 20.2 Severe Community-Acquired Pneumonia & Empyema 20.3 Acute Severe Epistaxis & Airway Obstruction

21 Chapter 21: Acute Traumatic Injuries & Wound Care

21.1 Major Trauma Resuscitation & Initial Assessment 21.2 Burn Assessment, Inhalation Injury & Resuscitation 21.3 Laceration Management, Complex Wounds & Animal Bites

22 Chapter 22: Acute Orthopedic & Musculoskeletal Emergencies

22.1 Acute Ambulatory Fractures & Initial Splinting 22.2 Compartment Syndrome & Major Orthopedic Trauma 22.3 Septic Arthritis & Acute Microcrystalline Crises

23 Chapter 23: Severe Infections, Sepsis & Systemic Emergencies

23.1 Sepsis, Septic Shock & Initial Fluid Resuscitation 23.2 Necrotizing Soft Tissue Infections & Severe CNS Infections 23.3 Anaphylaxis Diagnosis, Epinephrine Dosing & Airway Protection

24 Chapter 24: Metabolic, Endocrine & Electrolyte Emergencies

24.1 Diabetic Ketoacidosis & Hyperosmolar Hyperglycemic State 24.2 Critical Electrolyte Emergencies: Dyskalemias & Dysnatremias 24.3 Severe Calcium Abnormalities & Acute Adrenal Crisis

25 Chapter 25: Hematologic, Urologic & Dental Emergencies

25.1 Severe Symptomatic Anemias & Coagulopathic Emergencies 25.2 Testicular Torsion, Priapism & Acute Urinary Retention 25.3 Urgent Odontogenic Infections & Dental Trauma

26 Chapter 26: Psychiatric, Behavioral & Obstetric/Gynecologic Emergencies

26.1 Suicidal Ideation, Acute Agitation & Behavioral Emergencies 26.2 Acute Physical & Sexual Assault Care 26.3 Life-Threatening Vaginal Bleeding & Ectopic Pregnancy 26.4 Environmental Heat Stroke & Severe Hypothermia

27 Chapter 27: Acute Head, Neck & Neurologic Symptoms

27.1 Primary Acute Headaches: Migraine, Tension & Cluster 27.2 Concussion & Minor Closed Head Injury Evaluation 27.3 Transient Ischemic Attack Evaluation & ABCD2 Risk Scoring

28 Chapter 28: Acute Cranial Nerves, Hearing & Sensory Symptoms

28.1 Peripheral Neuropathies: Bell's Palsy, Carpal Tunnel & Radiculopathy 28.2 Acute Tinnitus, Sudden Sensorineural Hearing Loss & Cerumen Impaction 28.3 Acute Dizziness, Benign Paroxysmal Positional Vertigo & Vestibular Neuritis

29 Chapter 29: Acute Upper Respiratory Tract Infections

29.1 Acute Viral Rhinosinusitis vs. Bacterial Rhinosinusitis 29.2 Acute Pharyngitis: Group A Streptococcus & Centor Criteria 29.3 Acute Otitis Media, Otitis Externa & Serous Effusion

30 Chapter 30: Acute Lower Respiratory Infections & Cough

30.1 Influenza, COVID-19 & Viral Respiratory Syndromes 30.2 Acute Bronchitis & Lower Respiratory Tract Infections 30.3 Ambulatory Community-Acquired Pneumonia

31 Chapter 31: Allergic, Nasal & Non-Infectious Pulmonary Conditions

31.1 Allergic Rhinitis & Acute Non-Anaphylactic Allergic Reactions 31.2 Acute Dyspnea in Ambulatory Care 31.3 Interstitial Lung Diseases & Sarcoidosis Presentation

32 Chapter 32: Acute Chest, Cardiac & Vascular Symptoms

32.1 Palpitations Evaluation & Arrhythmia Triage in Primary Care 32.2 Deep Vein Thrombosis & Superficial Thrombophlebitis 32.3 Ambulatory Hypotension & Orthostasis Evaluation

33 Chapter 33: Acute Upper Gastrointestinal Conditions

33.1 Peptic Ulcer Disease & Gastritis 33.2 Dysphagia, Esophagitis & Acute Esophageal Disorders 33.3 Acute Nausea, Vomiting & Foodborne Illness

34 Chapter 34: Acute Lower Gastrointestinal Conditions

34.1 Acute Infectious Diarrhea & Gastroenteritis 34.2 Acute Constipation & Functional Bowel Changes 34.3 Ano-Rectal Disorders: Hemorrhoids, Fissures, Abscesses & Pruritus Ani

35 Chapter 35: Inflammatory, Functional & Malabsorptive GI Disorders

35.1 Acute Flares of Inflammatory Bowel Disease 35.2 Irritable Bowel Syndrome: Diagnosis, Subtyping & Management 35.3 Celiac Disease & Malabsorption Syndromes

36 Chapter 36: Acute Abdominal, Hepatic & Biliary Disorders

36.1 Ambulatory Abdominal & Pelvic Pain Triage 36.2 Acute Cholecystitis, Biliary Colic & Pancreatitis 36.3 Acute Liver Injury & Viral Hepatitis

37 Chapter 37: Acute Abdominal Wall, Hernias & Dental Conditions

37.1 Abdominal Wall, Inguinal & Ventral Hernias 37.2 Acute Dental Pain, Odontogenic Abscess & Aphthous Ulcers 37.3 Acute Edema: Unilateral vs. Bilateral Diagnostic Evaluation

38 Chapter 38: Acute Infectious Dermatoses

38.1 Bacterial Skin Infections: Impetigo, Cellulitis & Cutaneous Abscesses 38.2 Fungal Skin Infections: Tinea Corporis, Cruris, Pedis & Onychomycosis 38.3 Viral Cutaneous Infections: Herpes Simplex, Zoster & Molluscum Contagiosum

39 Chapter 39: Inflammatory, Allergic & Autoimmune Dermatoses

39.1 Atopic Dermatitis, Contact Dermatitis & Eczematous Flares 39.2 Non-Infectious Rashes: Urticaria, Drug Eruptions & Erythema Multiforme 39.3 Cutaneous Malignancies & Premalignant Lesions: AK, BCC, SCC & Melanoma

40 Chapter 40: Acute Shoulder, Elbow & Upper Extremity Injuries

40.1 Rotator Cuff Pathology, Tendinopathy & Shoulder Impingement 40.2 Lateral & Medial Epicondylitis, Olecranon Bursitis & Elbow Sprains 40.3 Wrist & Hand Soft-Tissue Injuries: De Quervain, TFCC & Finger Sprains

41 Chapter 41: Acute Knee, Ankle & Lower Extremity Injuries

41.1 Meniscal Tears, Ligamentous Knee Injuries & Patellofemoral Pain 41.2 Ankle Sprains, Ottawa Ankle Rules & Achilles Tendinopathy 41.3 Plantar Fasciitis, Shin Splints & Overuse Syndromes

42 Chapter 42: Acute Ambulatory Fractures & Dislocations

42.1 Distal Radius, Scaphoid & Common Upper Extremity Fractures 42.2 Metatarsal, Clavicle & Common Lower Extremity Fractures 42.3 Joint Dislocation Management: Nursemaid's Elbow & Shoulder Subluxation

43 Chapter 43: Acute Axial Musculoskeletal Pain & Falls

43.1 Acute Low Back Pain: Red Flags, Strain & Disc Herniation 43.2 Acute Cervical Strain, Whiplash & Axial Neck Pain 43.3 Evaluation of Falls in Ambulatory & Older Patients

44 Chapter 44: Acute Inflammatory Arthropathies & Generalized Pain

44.1 Acute Inflammatory Arthritis & Spondyloarthropathies 44.2 Myalgias, Rhabdomyolysis & Post-Viral Pain Syndromes 44.3 Acute Non-Headache Pain Management Strategies

45 Chapter 45: Acute Renal, Urinary & Genitourinary Conditions

45.1 Uncomplicated UTI, Pyelonephritis & Acute Urethritis 45.2 Hematuria Workup & Glomerulonephritis 45.3 Nephrolithiasis & Acute Urinary Tract Obstruction

46 Chapter 46: Acute Male Genitourinary & Prostatic Conditions

46.1 Acute Prostatitis, Epididymitis & Orchitis 46.2 Acute Scrotal Pain: Torsion vs Appendage, BPH & Male Genital Emergencies 46.3 Acute Urinary Retention & Incontinence Evaluation

47 Chapter 47: Acute Women's Health & Early Pregnancy Care

47.1 Early Pregnancy Diagnosis, Dating & Initial Complications 47.2 Abnormal Uterine Bleeding & Acute Menstrual Disorders 47.3 Premenstrual Syndrome & Premenstrual Dysphoric Disorder

48 Chapter 48: Breast Disorders, STIs & Pediatric Elimination

48.1 Palpable Breast Mass, Mastitis & Nipple Discharge 48.2 Sexually Transmitted Infections: Diagnosis, Staging & CDC Guidelines 48.3 Pediatric Enuresis & Encopresis

49 Chapter 49: Systemic Signs, Metabolic Dysregulation & Miscellaneous Infections

49.1 Acute Fever, Sepsis Screening & FUO in Primary Care 49.2 Acute Hyperglycemia & Symptomatic Hypoglycemia 49.3 Electrolyte Abnormalities: Mild-to-Moderate Disturbances 49.4 Vector-Borne, Tick-Borne & Rickettsial Illnesses

50 Chapter 50: Chronic Cardiovascular Diseases: Hypertension & Ischemia

50.1 Essential Hypertension Management: 2025 AHA/ACC Guideline & JNC Strategies 50.2 Chronic Coronary Artery Disease & Post-MI Secondary Prevention 50.3 Chronic Heart Failure: HFrEF, HFpEF & Quadruple GDMT

51 Chapter 51: Chronic Vascular, Valvular & Dyslipidemic Diseases

51.1 Peripheral Arterial Disease & Claudication 51.2 Chronic Valvular Heart Disease & Murmur Evaluation 51.3 Lipid Disorders & ASCVD Risk-Based Statin Therapy

52 Chapter 52: Chronic Respiratory Diseases: Asthma & COPD

52.1 Chronic Asthma Management: GINA Stepwise SMART Therapy 52.2 Chronic Obstructive Pulmonary Disease: GOLD Recommendations 52.3 Solitary Pulmonary Nodule Evaluation & Fleischner Society Criteria

53 Chapter 53: Chronic Metabolic Diseases: Diabetes Mellitus

53.1 Type 2 Diabetes Management: ADA Pharmacotherapy Algorithms 53.2 Type 1 Diabetes: Basal-Bolus Insulin, CGMs & Diabetic Complications 53.3 Diabetic Microvascular & Macrovascular Disease Surveillance

54 Chapter 54: Obesity, Nutrition & Metabolic Bone Diseases

54.1 Medical & Behavioral Management of Obesity & Incretin Mimetics 54.2 Osteoporosis & Metabolic Bone Disease: DEXA, FRAX & Antiresorptives 54.3 Nutritional Deficiencies: Vitamin D, B12, Iron & Malnutrition

55 Chapter 55: Chronic Endocrine Disorders

55.1 Primary & Subclinical Hypothyroidism, Hyperthyroidism & Nodules 55.2 Adrenal Disorders: Addison's Disease & Cushing's Syndrome 55.3 Hypercalcemia, Hyperparathyroidism & Pituitary Disorders

56 Chapter 56: Chronic Kidney Disease & Venous Disorders

56.1 Chronic Kidney Disease: KDIGO Staging & Renoprotective Therapy 56.2 Chronic Venous Insufficiency, Stasis Dermatitis & Lymphedema 56.3 Chronic Electrolyte & Acid-Base Management in CKD

57 Chapter 57: Chronic Gastrointestinal & Hepatic Diseases

57.1 Gastroesophageal Reflux Disease, Barrett's Esophagus & Dyspepsia 57.2 Chronic Liver Disease: MASLD/NAFLD, Cirrhosis & Portal Hypertension 57.3 Viral Hepatitis B & C: Long-Term Monitoring & DAA Therapy

58 Chapter 58: Colorectal Surveillance & Chronic Pancreaticobiliary Care

58.1 Post-Polypectomy Colorectal Polyp Surveillance Guidelines 58.2 Chronic Pancreatitis & Exocrine Pancreatic Insufficiency 58.3 Chronic Nausea, Gastroparesis & Functional GI Disorders

59 Chapter 59: Chronic Musculoskeletal & Rheumatologic Disorders

59.1 Osteoarthritis: Hip, Knee & Hand Management 59.2 Spinal Conditions: Spinal Stenosis, Spondylolisthesis & Compression Fractures 59.3 Chronic Myopathies & Fibromyalgia Syndrome

60 Chapter 60: Chronic Neurologic & Neurodegenerative Disorders

60.1 Dementia: Alzheimer's, Vascular & Lewy Body Disease 60.2 Parkinson's Disease & Essential Tremor 60.3 Epilepsy: Chronic Antiseizure Medications & Post-Stroke Care

61 Chapter 61: Chronic Peripheral Nerves, Pain & Sensory Disorders

61.1 Diabetic & Chronic Peripheral Neuropathies 61.2 Chronic Pain Syndromes & Chronic Daily Headaches 61.3 Chronic Tinnitus, Presbycusis & Persistent Dizziness

62 Chapter 62: Chronic Psychiatric Disorders

62.1 Major Depressive Disorder & Generalized Anxiety Disorder 62.2 Bipolar Disorder: Maintenance Pharmacotherapy & Lithium Monitoring 62.3 Adult & Pediatric Attention-Deficit/Hyperactivity Disorder

63 Chapter 63: Chronic Behavioral Health & Neurodevelopmental Conditions

63.1 Chronic Behavioral Conditions: PTSD, OCD & Somatization 63.2 Autism Spectrum Disorder & Intellectual Disabilities 63.3 Eating Disorders: Anorexia Nervosa, Bulimia & Binge Eating

64 Chapter 64: Chronic Substance Use Disorders & Tobacco Cessation

64.1 Alcohol Use Disorder: Pharmacotherapy & Relapse Prevention 64.2 Opioid & Stimulant Use Disorders: MOUD & Harm Reduction 64.3 Longitudinal Tobacco Cessation Pharmacotherapy

65 Chapter 65: Chronic Dermatologic Conditions

65.1 Acne Vulgaris, Rosacea & Seborrheic Dermatitis 65.2 Chronic Plaque Psoriasis & Biologic Therapies 65.3 Chronic Eczema, Hidradenitis Suppurativa & Cutaneous Lupus

66 Chapter 66: Chronic Reproductive, Infectious & Geriatric Special Care

66.1 Chronic Menstrual Disorders, Infertility & Sexual Dysfunction 66.2 Menopause Management & Hormone Replacement Therapy 66.3 Chronic HIV Infection Management & Primary Care Integration 66.4 Gender-Affirming Primary Care & Hormone Therapy 66.5 Advance Care Planning, Palliative Care & End-of-Life Symptom Control

67 Chapter 67: Continuity Care: Sleep, Fatigue, Cancer, Pregnancy & the Adult Preventive Visit

67.1 Chronic Insomnia & Obstructive Sleep Apnea 67.2 Chronic Malaise, Fatigue & ME/CFS 67.3 Primary Care During Cancer Treatment & Survivorship 67.4 Routine Prenatal Care & Longitudinal Pregnancy Management 67.5 The Periodic Adult Health Examination & Medicare Annual Wellness Visit

30.2 Acute Bronchitis & Lower Respiratory Tract Infections

Key Takeaways Explain This Topic AI

Acute bronchitis is a self-limiting inflammation of the large tracheobronchial airways characterized by an acute cough lasting 1 to 3 weeks (mean duration 18 days) in an ambulatory patient without chronic underlying lung disease.

Over 90% of acute bronchitis cases are viral in etiology; routine antibiotic prescription is strongly discouraged by Choosing Wisely and ACP/CDC guidelines, as antibiotics provide no clinically meaningful benefit (reducing cough by ~12 hours) while causing adverse drug reactions, C. difficile colitis, and antimicrobial resistance.

Purulent (yellow or green) sputum is caused by myeloperoxidase released from degenerating leukocytes and tracheobronchial epithelial desquamation; it is an expected feature of viral bronchitis and does NOT indicate bacterial infection or justify antibiotic therapy.

The vital signs and lung examination rule (normal heart rate <100 bpm, respiratory rate <20 breaths/min, oral temperature <38.0°C [100.4°F], and absence of focal crackles, egophony, bronchial breath sounds, or dullness) has a negative predictive value >99% for pneumonia, eliminating the need for chest radiography.

Pertussis (Bordetella pertussis) progresses through catarrhal (1-2 weeks; highly contagious), paroxysmal (2-6 weeks; staccato coughing fits, inspiratory 'whoop', post-tussive emesis, absolute lymphocytosis), and convalescent stages; nasopharyngeal PCR is the diagnostic standard during the first 3-4 weeks, and macrolides (azithromycin) eradicate carriage to halt transmission, requiring post-exposure prophylaxis for all household contacts.

Last updated: September 2026

Acute Bronchitis: Pathophysiology, Natural History & Etiology

Acute bronchitis is one of the most frequent reasons for outpatient ambulatory visits in primary care, accounting for over 10 million office evaluations annually in the United States. It is defined as a self-limiting inflammation of the large conducting airways (tracheobronchial tree) presenting as an acute cough with or without sputum production in a patient without underlying chronic lung disease (such as COPD, asthma, bronchiectasis, or cystic fibrosis).

Pathophysiology & Natural History

Mechanisms : Inoculation of the respiratory tract leads to hyperemic bronchial mucosa, desquamation of ciliated columnar epithelial cells, lymphocytic infiltration of the submucosa, excessive mucous secretion, and transient bronchial hyperresponsiveness.

The Expected 3-Week Timeline : Clinical studies demonstrate that the natural history of acute bronchitis features a cough that averages 18 days (range 1 to 3 weeks) , with up to 25% of patients continuing to cough beyond 3 to 4 weeks. Clinician education regarding this 18-day average is paramount: patients who expect coughs to resolve within 5 to 7 days frequently request antibiotics under the false premise of an abnormally prolonged illness.

Microbial Etiology

Viral Pathogens (>90%) : The vast majority of acute bronchitis presentations are viral, including:

• Rhinovirus and Enterovirus (most prevalent);
• Coronaviruses (common human strains);
• Influenza A and Influenza B viruses;
• Respiratory Syncytial Virus (RSV);
• Parainfluenza viruses;

Human Metapneumovirus (hMPV).

Atypical Bacterial Pathogens (<10%) : Uncommon causes include Bordetella pertussis , Mycoplasma pneumoniae , and Chlamydophila pneumoniae .

The Critical Negative Rule : Typical pyogenic bacteria ( Streptococcus pneumoniae , Haemophilus influenzae , Moraxella catarrhalis ) do NOT cause acute bronchitis in ambulatory patients with normal baseline lung architecture ! These organisms cause pneumonia when alveolar spaces are infected, or acute exacerbations in patients with pre-existing COPD, but they are not primary pathogens in uncomplicated acute bronchitis.

The Sputum Color Fallacy: Debunking Purulence

A persistent clinical myth in ambulatory medicine is that yellow or green (purulent) sputum signifies bacterial infection requiring antimicrobial therapy.

The Cellular Reality : Sputum purulence is driven by the release of myeloperoxidase , a green heme-containing enzyme released from the cytoplasmic granules of activated polymorphonuclear neutrophils (PMNs), accompanied by cellular debris from desquamated bronchial epithelium.

Evidence-Based Rule : Multiple randomized trials have demonstrated that the presence of purulent, discolored, or thick green sputum correlates with intense mucosal inflammation, NOT the presence of bacterial pathogens. Purulent sputum does not predict bacterial etiology, nor does it predict clinical response to antibacterial therapy .

Choosing Wisely & Antibiotic Stewardship in Acute Bronchitis

Despite clear clinical guidelines, acute bronchitis remains one of the leading drivers of inappropriate antibiotic prescribing in adult ambulatory medicine, with antibiotics historically prescribed in 60% to 80% of clinical visits.

Evidence Against Antibiotic Prescribing

Negligible Clinical Efficacy : A landmark Cochrane Systematic Review of 17 randomized controlled trials (over 5,000 patients) demonstrated that routine antibiotic prescribing reduced the total duration of cough by approximately 0.5 days (approx. 12 hours) over a 2-to-3-week illness—a clinically imperceptible benefit.

Significant Adverse Harms : Approximately 1 in 5 to 1 in 10 patients prescribed antibiotics experience adverse drug events, including:

• Gastrointestinal distress (nausea, severe vomiting, abdominal cramping, severe diarrhea);
• Vulvovaginal candidiasis;
• Allergic cutaneous exanthems, urticaria, and life-threatening anaphylaxis;
• Life-threatening Clostridioides difficile colitis;

Escalation of individual and community antimicrobial resistance.

Guidelines Consensus : The American College of Physicians (ACP), Centers for Disease Control and Prevention (CDC), and American Academy of Family Physicians (AAFP) Choosing Wisely campaign explicitly recommend:

"Do not prescribe antibiotics for uncomplicated acute bronchitis in otherwise healthy patients without chronic lung disease."

Communication Strategies to Avoid Antibiotic Overuse

Clinicians often prescribe antibiotics due to perceived patient pressure or fear of patient dissatisfaction. Evidence demonstrates that patient satisfaction correlates with adequate communication and validation , not antibiotic prescriptions:

Validate Distress : Acknowledge the disruptive nature of the cough ("I can see how exhausted you are from coughing through the night").

Avoid Ambiguous Labels : Avoid terms like "chest cold" or "bronchial infection" without explaining they are viral. Explain: "You have acute viral bronchitis, which is an inflammation of the airways caused by a virus. Antibiotics kill bacteria, not viruses, and taking them will not make your cough resolve any faster while exposing you to side effects like diarrhea and rash."

Set Realistic Expectations : Emphasize that post-viral airway hyperreactivity takes an average of 18 days to resolve.

Provide a Written Symptom-Relief Plan : Outline non-pharmacologic and pharmacologic antitussive strategies.

Safety-Netting & Delayed Prescribing : Instruct the patient to contact the clinic if they develop new high fevers, shortness of breath, hemoptysis, or if symptoms worsen after initial improvement.

Clinical Rule-Out of Pneumonia: The Vital Signs & Exam Rule

The primary clinical challenge in evaluating acute cough is differentiating self-limited acute bronchitis from potentially life-threatening community-acquired pneumonia (CAP) without ordering unnecessary chest radiographs on every patient. ACUTE COUGH EVALUATION IN AMBULATORY ADULTS

• Acute Cough Illness (<=3 Weeks)
• │
• ▼
• Check Vital Signs & Perform Lung Exam
• │
• ┌──────────────────────────┴──────────────────────────┐
• ▼ ▼
• NORMAL VITAL SIGNS & EXAM ANY ABNORMAL FINDING
• Heart Rate <100 bpm • Heart Rate >=100 bpm
• Respiratory Rate <20 breaths/min • Respiratory Rate >=20 bpm
• Temperature <38.0°C (100.4°F) • Temperature >=38.0°C (100.4°F)
• Lung Exam Normal (no crackles, • Focal lung crackles, egophony,
• bronchial breath sounds, dullness) or dullness to percussion
• Normal mental status • SpO2 <95% on room air
• │ • Age >=65 with acute confusion
• ▼ │
• ================================= ▼
• NEGATIVE PREDICTIVE VALUE >99% OBTAIN CHEST RADIOGRAPH
• FOR PNEUMONIA (PA and Lateral Views)
• Chest Radiograph NOT Indicated │
• Diagnosis: ACUTE BRONCHITIS ┌───────────┴───────────┐
• Strict Antibiotic Stewardship ▼ ▼
• Reassurance & Symptomatic Relief Infiltrate Present Normal CXR
• Diagnose CAP Acute Bronchitis
• The Evidence-Based Vital Signs Decision Rule

A patient presenting with acute cough who meets ALL four of the following criteria :

• Heart rate < 100 beats/min;
• Respiratory rate < 20 breaths/min;
• Oral body temperature < 38.0°C (100.4°F); AND

Normal chest examination (absence of focal crackles, egophony, bronchial breath sounds, or dullness to percussion);

Has a negative predictive value (NPV) exceeding 99% for pneumonia . In these patients, posteroanterior (PA) and lateral chest radiography is unnecessary, unhelpful, and not cost-effective.

• Indications for Chest Radiography (PA and Lateral)
• Any abnormal vital sign: Tachycardia (HR ≥100), tachypnea (RR ≥20), or documented fever (T ≥38.0°C);

Any focal auscultatory abnormality: Localized crackles, bronchial breath sounds, whispered pectoriloquy, egophony, or asymmetric dullness to percussion;

Pulse oximetry SpO2 <95% on ambient room air;

Age ≥65 years presenting with altered mental status, delirium, acute confusion, or unexplained functional decline (frequently lack fever and cough in pneumonia);

Presence of red-flag symptoms: Frank hemoptysis, severe pleuritic chest pain, or unremitting high fevers.

Symptomatic & Supportive Pharmacotherapy

Therapeutic Agent Clinical Indication Mechanism & Dosing Clinical Evidence & Safety Pearls

Honey Nocturnal cough relief in patients >1 year of age 1 to 2 teaspoons (5 to 10 mL) orally before bedtime Proven superior to diphenhydramine and placebo for cough suppression. CONTRAINDICATED in infants <1 year due to the fatal risk of infant botulism ( Clostridium botulinum spores).

Dextromethorphan Troublesome dry nocturnal cough Centrally acting NMDA receptor antagonist / sigma-1 agonist (30 mg PO Q6-8H) Modest cough reflex suppression. Caution: Risk of serotonin syndrome when co-administered with SSRIs, SNRIs, or MAOIs.

Inhaled Beta-2 Agonists (Albuterol MDI) ONLY if objective wheezing or bronchospasm is present on physical exam 2 puffs (90 mcg/puff) via spacer Q4-6H PRN wheezing Provides symptom relief in patients with documented airway hyperreactivity/wheezing. In patients without wheezing , beta-agonists offer zero benefit and cause tremor, anxiety, and tachycardia.

Oral Analgesics / NSAIDs Malaise, myalgias, chest wall soreness, and headache Ibuprofen 400-600 mg PO Q6-8H or Acetaminophen 650-1000 mg PO Q6H PRN Alleviates musculoskeletal chest wall soreness from violent coughing paroxysms and controls low-grade fever.

Systemic Corticosteroids (Prednisone) NOT RECOMMENDED in acute bronchitis Oral glucocorticoids Randomized controlled trials show no reduction in cough severity or duration in patients without asthma or COPD. Causes acute hyperglycemia, insomnia, and mood lability.

Codeine & Opioid Antitussives NOT RECOMMENDED Centrally acting opioid receptor agonists No superior efficacy compared to dextromethorphan; high risks of sedation, constipation, nausea, dependency, and fatal respiratory depression.

Pertussis ("Whooping Cough", Bordetella pertussis )

Pertussis is an acute, highly contagious respiratory tract infection caused by the fastidious Gram-negative coccobacillus Bordetella pertussis . Despite childhood immunization programs, pertussis incidence has surged in adolescents and adults due to waning vaccine-induced immunity following acellular pertussis (DTaP/Tdap) vaccines.

Clinical Staging & Natural History CLINICAL STAGES OF PERTUSSIS

• Catarrhal Stage (1-2 Weeks) Paroxysmal Stage (2-6+ Weeks) Convalescent Stage (Months)
• ┌───────────────────────────┐ ┌───────────────────────────────┐ ┌───────────────────────────┐
• │ • Rhinorrhea, low fever │ │ • Staccato coughing bursts │ │ • 'Cough of 100 days' │
• │ • Indistinguishable from │ │ • Inspiratory 'whoop' │ │ • Gradual decrease in │
• │ viral upper resp. inf. │ │ • Post-tussive emesis │ │ cough paroxysms │
• │ • MOST CONTAGIOUS PHASE │ │ • Absolute lymphocytosis │ │ • Paroxysms can recur │
• │ • Antibiotics alter course│ │ • Subconjunctival hemorrhages │ │ with subsequent viral │
• │ if started here │ │ • Antibiotics halt spread │ │ respiratory infections │
• └───────────────────────────┘ └───────────────────────────────┘ └───────────────────────────┘
• 1. Catarrhal Stage (1 to 2 Weeks)

Manifests as an insidious, mild upper respiratory illness: low-grade fever, mild rhinorrhea, sneezing, lacrimation, and an occasional non-productive hack.

The Contagion Peak : This is the period of maximal communicability and bacterial shedding . Because symptoms are indistinguishable from a common cold, pertussis is rarely suspected or diagnosed during this window. Antimicrobial therapy initiated during this stage effectively abbreviates the clinical illness.

2. Paroxysmal Stage (2 to 6 Weeks, up to 10 Weeks)

Hallmarked by agonizing paroxysms of rapid, staccato, expiratory coughing bursts (often 5 to 15 coughs in a single exhalation), during which the patient is unable to breathe.

The paroxysm terminates with a forceful, massive inspiratory gasp against a partially closed, edematous glottis, producing the characteristic high-pitched inspiratory "whoop" .

Cardinal Diagnostic Signs:

• Post-tussive emesis (highly specific for pertussis in adults; positive likelihood ratio ~4.0);
• Post-tussive exhaustion, syncope, or apnea;

Bilateral subconjunctival hemorrhages, facial petechiae, and epistaxis from elevated intrathoracic and venous pressures;

Cough-induced rib fractures and inguinal hernias.

Atypical Presentation in Adults & Adolescents : In previously vaccinated adults with waning immunity, the classic inspiratory "whoop" is absent in over 50% of cases. The condition often manifests simply as an intractable, exhausting nocturnal cough persisting beyond 2 to 3 weeks with post-tussive retching.

Infants <6 Months : Do NOT develop the classic "whoop"; they present with life-threatening apneic spells , cyanosis, bradycardia, seizures, and cardiogenic collapse.

3. Convalescent Stage (Weeks to Months)

Gradual resolution of coughing paroxysms over several months (historically known as the "cough of 100 days" ). Cough paroxysms can temporarily re-emerge during subsequent viral respiratory tract infections.

Diagnostic Testing & Laboratory Evaluation

Complete Blood Count (CBC) : Marked absolute lymphocytosis (white blood cell count often 20,000 to 50,000/µL with >60% to 70% mature lymphocytes). Pertussis toxin blocks the extravasation of lymphocytes from the intravascular space into secondary lymphoid tissues.

Nasopharyngeal Swab for Pertussis PCR : The gold-standard diagnostic modality of choice during the first 3 to 4 weeks of cough (sensitivity >90%, specificity >95%). Swabs must use synthetic polyester or Dacron tips (calcium alginate or cotton tips inhibit PCR assays).

Nasopharyngeal Culture : Inoculated onto specialized selective media (Regan-Lowe or Bordet-Gengou charcoal agar). Highly specific (100%), but sensitive only during the initial 2 weeks of illness and requires 7 to 10 days of incubation.

Pertussis Serology (IgG Anti-Pertussis Toxin) : Preferred diagnostic modality when the patient presents after 3 to 4 weeks of cough , when bacterial shedding has ceased and PCR sensitivity drops precipitously.

Antimicrobial Treatment Protocols PERTUSSIS ANTIMICROBIAL REGIMENS

• First-Line (All Ages): MACROLIDES
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• AZITHROMYCIN (Preferred):

• Adults: 500 mg PO on Day 1, then 250 mg PO daily on Days 2-5
• Infants/Children: 10 mg/kg Day 1, then 5 mg/kg daily Days 2-5
• Preferred in neonates (lowest risk of pyloric stenosis)

• CLARITHROMYCIN:

- Adults: 500 mg PO BID for 7 days

• ERYTHROMYCIN:

• Adults: 500 mg PO QID for 14 days (GI toxicity, pyloric stenosis risk)
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Alternative (Macrolide Allergy / Intolerance):

• TRIMETHOPRIM-SULFAMETHOXAZOLE (TMP-SMX):

• Adults: 1 DS tablet (160/800 mg) PO BID for 14 days
• CONTRAINDICATIONS: Infants <2 months (kernicterus) & term pregnancy
• The Clinical Timing Paradox

Initiation ≤3 Weeks of Cough : Macrolide therapy started in the catarrhal or early paroxysmal stage significantly reduces symptom severity and shortens illness duration.

Initiation >3 Weeks of Cough : Initiating antibiotics after 3 to 4 weeks of cough DOES NOT alter or reduce clinical symptoms , because the tracheobronchial ciliated epithelium has already suffered extensive cytotoxic damage by pertussis toxin and tracheal cytotoxin. However, antibiotics are still universally indicated to eliminate viable nasopharyngeal carriage and halt secondary transmission to susceptible contacts (especially unimmunized infants) .

Post-Exposure Antimicrobial Prophylaxis (PEP)

Universal Household Recommendation : PEP is recommended for all household and close contacts of a confirmed pertussis case, regardless of their personal immunization status , within 21 days of exposure.

High-Risk Prioritization : Prophylaxis is mandatory if the contact setting includes:

• Infants aged <1 year (highest mortality risk);
• Pregnant women in their third trimester (to prevent transmission to the newborn);
• Individuals with pre-existing chronic cardiopulmonary disease or severe immunocompromise;

Daycare attendees and staff.

Prophylactic Regimen : Identical dosing regimens and durations as active treatment (e.g., Azithromycin 5-day course).

Immunization & Prevention Across the Lifespan

Adolescent & Adult Booster : Single lifetime dose of Tdap for all adults aged 19 to 64 years who have not previously received it, followed by routine Td or Tdap decennial boosters every 10 years.

Pregnancy Protocol : A single dose of Tdap is recommended during EVERY pregnancy, ideally between 27 and 36 weeks of gestation , regardless of the mother's prior vaccination history. This timing optimizes maternal anti-pertussis IgG production and maximizes active transplacental transfer to the fetus, conferring vital passive immunity during the vulnerable initial 2 months of life prior to the infant's primary DTaP immunization series.

Loading diagram... Clinical Pathway for Acute Cough, Bronchitis Stewardship, and Pertussis