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Infectious Diseases and Microbiology: Sore Throat
Basics
Description
Sore throat refers to painful inflammation of the pharynx, typically worse with swallowing. Common infectious causes are covered elsewhere; the emphasis here is recognizing distinguishing clinical features and considering noninfectious etiologies.
Approach to the Patient
First assess for airway compromise and decide whether the illness is localized or part of a systemic process, most often viral. Clarify symptom type and duration and ask about hoarseness and fever. History should include sick contacts, oral–genital sexual exposure, recent weight loss, and other features suggesting noninfectious causes such as neoplasms. Findings that strongly support streptococcal pharyngitis include fever, marked tonsillar exudate and enlargement, tender anterior cervical nodes, myalgias, and supportive epidemiology such as age, season, and community colonization prevalence. Conjunctivitis points toward viral illness. When clinical and epidemiologic clues suggest gonococcal pharyngitis or diphtheria, use specific microbiologic techniques and begin appropriate therapy promptly. Differentiate laryngitis, croup, and other hoarseness syndromes from epiglottitis. The main practical distinction is group A streptococcal versus nonstreptococcal pharyngitis, confirmed by throat culture or rapid antigen testing.
Epidemiology
Most pharyngitis is viral, accounting for roughly 90% of adult cases and 70% of pediatric cases. Group A beta-hemolytic Streptococcus is more common in children than adults. Antibiotic prescribing is frequent in adults with pharyngitis. In outbreaks involving rheumatogenic strains, untreated group A streptococcal infection can be followed by acute rheumatic fever in a small but meaningful percentage. Lancefield groups C and G streptococci can cause syndromes similar to group A disease and are often opportunistic or healthcare-associated. Arcanobacterium hemolyticum is seen particularly in adolescents and young adults. Parainfluenza infection is most common in children.
General Prevention
Advise patients with streptococcal pharyngitis to avoid close contact with others, and counsel on safer sex practices to reduce sexually transmitted causes.
Etiology
Acute pharyngitis is most often viral, including rhinovirus, coronavirus, influenza A/B, and parainfluenza, and may involve broader respiratory tract symptoms. Acute laryngitis is usually viral and can be caused by rhinovirus, influenza, parainfluenza, coxsackievirus, adenovirus, or respiratory syncytial virus. Some viruses produce characteristic patterns, including herpangina from coxsackie A, infectious mononucleosis from Epstein–Barr virus or cytomegalovirus, HSV gingivostomatitis, and adenoviral pharyngoconjunctival fever. Primary HSV-1 can cause acute pharyngitis, and HSV-2 can cause similar illness after oral–genital exposure. Acute pharyngitis can occur during primary HIV infection. The key bacterial cause is group A Streptococcus, with additional causes including groups C and G streptococci, Arcanobacterium hemolyticum, Neisseria gonorrhoeae, Corynebacterium diphtheriae, Mycoplasma pneumoniae, and Chlamydophila pneumoniae. Sore throat can also occur with systemic infections such as toxoplasmosis, plague, brucellosis, leptospirosis, secondary syphilis, Yersinia infections, and tularemia. Histoplasma and Blastomyces can cause laryngeal nodules with or without ulceration. Candida can cause sore throat with thrush in immunosuppressed patients or those with mucocutaneous candidiasis. West Nile virus can present as a febrile illness with malaise, headache, myalgias, rash, and occasional pharyngitis. Lemierre syndrome can present with sore throat. Deep neck infections include parapharyngeal abscess from spread of tonsillitis, pharyngitis with adenoid involvement, parotitis, mastoiditis, or periodontal infection, and retropharyngeal abscess from spread, lymphatic seeding, trauma, or cervical osteomyelitis extension. Acute necrotizing pharyngeal infections can cause foul breath, fever, and choking sensation, often associated with ulcerative gingivitis. Ludwig angina arises from dental infection near the third molar and causes rapidly spreading bilateral submandibular and sublingual cellulitis with swelling, pain, trismus, drooling, tongue displacement, and progressive dysphagia and sore throat that can lead to airway obstruction. PFAPA syndrome affects young children and causes periodic high fevers lasting several days with aphthous stomatitis, pharyngitis, and cervical adenitis, recurring at regular short intervals without other symptoms.
Diagnosis
Parapharyngeal space infection typically causes toxic appearance, fever, sore throat, dysphagia, and leukocytosis, with possible neck rigidity or contralateral torticollis; advanced disease can produce dyspnea and stridor. Acute necrotizing pharyngeal infection presents with swollen erythematous ulcerated tonsillar pillars covered by a gray membrane that peels easily and is often accompanied by lymphadenopathy. In infectious mononucleosis, pharyngitis is most prominent in the first two weeks. Herpangina presents with fever, sore throat, myalgias, and vesicles on the soft palate between the uvula and tonsils. Tuberculous laryngitis can cause mucosal hyperemia, thickening, nodules, and ulcerations.
Diagnostic Tests and Interpretation
Laboratory Studies
Throat culture is the reference standard for streptococcal diagnosis but takes 24–72 hours. Rapid antigen tests are highly specific but have variable sensitivity.
Imaging
Retropharyngeal infection may be suggested by lateral neck soft-tissue radiography, while CT or MRI best defines source and extent.
Diagnostic Procedures/Other
In suspected tuberculous laryngitis, biopsy may show granulomas with acid-fast bacilli, with cultures needed for confirmation and susceptibility testing.
Differential Diagnosis
Viral pharyngitis commonly includes sore throat with coryza and cough, an inflamed edematous pharynx, and usually no exudate, though adenovirus and mononucleosis can be exudative. Fever, tender anterior cervical nodes, erythematous pharynx with or without tonsillar enlargement or exudate, and absence of cough support streptococcal pharyngitis in children and adults. Mycoplasma-related sore throat typically occurs in young healthy patients with mild pharyngitis and prominent tracheobronchitis symptoms.
Treatment
Medications
Patients at high risk of complications from streptococcal infection, such as those with prior rheumatic carditis or valvular disease, should receive immediate antibiotics while awaiting culture confirmation. Parapharyngeal space infection management includes airway protection, operative drainage, and intravenous antibiotics targeting streptococci and oral anaerobes, using regimens such as penicillin plus metronidazole, cefoxitin, or ampicillin-sulbactam. For streptococcal pharyngitis, a single intramuscular dose of benzathine penicillin may be slightly more effective than oral penicillin VK and ensures adherence.
Ongoing Care and Follow-Up
Post-viral chronic fatigue syndrome can include fatigue, fever, sore throat, painful lymph nodes, myalgias, arthralgias, sleep disturbance, and headache. Appropriate treatment and monitoring of group A streptococcal infection aims to prevent nonsuppurative complications such as acute rheumatic fever and glomerulonephritis, reduce toxic complications and local suppurative spread, limit transmission, and shorten illness duration. Sore throat can also precede broader constitutional symptoms that culminate in viral encephalitis.
Complications
Peritonsillar abscess can follow untreated streptococcal pharyngitis and presents with unilateral swelling and erythema and uvular deviation. Parapharyngeal infections can lead to airway obstruction, aspiration after intraoral rupture, jugular vein thrombophlebitis with pulmonary emboli, carotid artery erosion, and mediastinitis.
Basics
Description
Sore throat refers to painful inflammation of the pharynx, typically worse with swallowing. Common infectious causes are covered elsewhere; the emphasis here is recognizing distinguishing clinical features and considering noninfectious etiologies.
Approach to the Patient
First assess for airway compromise and decide whether the illness is localized or part of a systemic process, most often viral. Clarify symptom type and duration and ask about hoarseness and fever. History should include sick contacts, oral–genital sexual exposure, recent weight loss, and other features suggesting noninfectious causes such as neoplasms. Findings that strongly support streptococcal pharyngitis include fever, marked tonsillar exudate and enlargement, tender anterior cervical nodes, myalgias, and supportive epidemiology such as age, season, and community colonization prevalence. Conjunctivitis points toward viral illness. When clinical and epidemiologic clues suggest gonococcal pharyngitis or diphtheria, use specific microbiologic techniques and begin appropriate therapy promptly. Differentiate laryngitis, croup, and other hoarseness syndromes from epiglottitis. The main practical distinction is group A streptococcal versus nonstreptococcal pharyngitis, confirmed by throat culture or rapid antigen testing.
Epidemiology
Most pharyngitis is viral, accounting for roughly 90% of adult cases and 70% of pediatric cases. Group A beta-hemolytic Streptococcus is more common in children than adults. Antibiotic prescribing is frequent in adults with pharyngitis. In outbreaks involving rheumatogenic strains, untreated group A streptococcal infection can be followed by acute rheumatic fever in a small but meaningful percentage. Lancefield groups C and G streptococci can cause syndromes similar to group A disease and are often opportunistic or healthcare-associated. Arcanobacterium hemolyticum is seen particularly in adolescents and young adults. Parainfluenza infection is most common in children.
General Prevention
Advise patients with streptococcal pharyngitis to avoid close contact with others, and counsel on safer sex practices to reduce sexually transmitted causes.
Etiology
Acute pharyngitis is most often viral, including rhinovirus, coronavirus, influenza A/B, and parainfluenza, and may involve broader respiratory tract symptoms. Acute laryngitis is usually viral and can be caused by rhinovirus, influenza, parainfluenza, coxsackievirus, adenovirus, or respiratory syncytial virus. Some viruses produce characteristic patterns, including herpangina from coxsackie A, infectious mononucleosis from Epstein–Barr virus or cytomegalovirus, HSV gingivostomatitis, and adenoviral pharyngoconjunctival fever. Primary HSV-1 can cause acute pharyngitis, and HSV-2 can cause similar illness after oral–genital exposure. Acute pharyngitis can occur during primary HIV infection. The key bacterial cause is group A Streptococcus, with additional causes including groups C and G streptococci, Arcanobacterium hemolyticum, Neisseria gonorrhoeae, Corynebacterium diphtheriae, Mycoplasma pneumoniae, and Chlamydophila pneumoniae. Sore throat can also occur with systemic infections such as toxoplasmosis, plague, brucellosis, leptospirosis, secondary syphilis, Yersinia infections, and tularemia. Histoplasma and Blastomyces can cause laryngeal nodules with or without ulceration. Candida can cause sore throat with thrush in immunosuppressed patients or those with mucocutaneous candidiasis. West Nile virus can present as a febrile illness with malaise, headache, myalgias, rash, and occasional pharyngitis. Lemierre syndrome can present with sore throat. Deep neck infections include parapharyngeal abscess from spread of tonsillitis, pharyngitis with adenoid involvement, parotitis, mastoiditis, or periodontal infection, and retropharyngeal abscess from spread, lymphatic seeding, trauma, or cervical osteomyelitis extension. Acute necrotizing pharyngeal infections can cause foul breath, fever, and choking sensation, often associated with ulcerative gingivitis. Ludwig angina arises from dental infection near the third molar and causes rapidly spreading bilateral submandibular and sublingual cellulitis with swelling, pain, trismus, drooling, tongue displacement, and progressive dysphagia and sore throat that can lead to airway obstruction. PFAPA syndrome affects young children and causes periodic high fevers lasting several days with aphthous stomatitis, pharyngitis, and cervical adenitis, recurring at regular short intervals without other symptoms.
Diagnosis
Parapharyngeal space infection typically causes toxic appearance, fever, sore throat, dysphagia, and leukocytosis, with possible neck rigidity or contralateral torticollis; advanced disease can produce dyspnea and stridor. Acute necrotizing pharyngeal infection presents with swollen erythematous ulcerated tonsillar pillars covered by a gray membrane that peels easily and is often accompanied by lymphadenopathy. In infectious mononucleosis, pharyngitis is most prominent in the first two weeks. Herpangina presents with fever, sore throat, myalgias, and vesicles on the soft palate between the uvula and tonsils. Tuberculous laryngitis can cause mucosal hyperemia, thickening, nodules, and ulcerations.
Diagnostic Tests and Interpretation
Laboratory Studies
Throat culture is the reference standard for streptococcal diagnosis but takes 24–72 hours. Rapid antigen tests are highly specific but have variable sensitivity.
Imaging
Retropharyngeal infection may be suggested by lateral neck soft-tissue radiography, while CT or MRI best defines source and extent.
Diagnostic Procedures/Other
In suspected tuberculous laryngitis, biopsy may show granulomas with acid-fast bacilli, with cultures needed for confirmation and susceptibility testing.
Differential Diagnosis
Viral pharyngitis commonly includes sore throat with coryza and cough, an inflamed edematous pharynx, and usually no exudate, though adenovirus and mononucleosis can be exudative. Fever, tender anterior cervical nodes, erythematous pharynx with or without tonsillar enlargement or exudate, and absence of cough support streptococcal pharyngitis in children and adults. Mycoplasma-related sore throat typically occurs in young healthy patients with mild pharyngitis and prominent tracheobronchitis symptoms.
Treatment
Medications
Patients at high risk of complications from streptococcal infection, such as those with prior rheumatic carditis or valvular disease, should receive immediate antibiotics while awaiting culture confirmation. Parapharyngeal space infection management includes airway protection, operative drainage, and intravenous antibiotics targeting streptococci and oral anaerobes, using regimens such as penicillin plus metronidazole, cefoxitin, or ampicillin-sulbactam. For streptococcal pharyngitis, a single intramuscular dose of benzathine penicillin may be slightly more effective than oral penicillin VK and ensures adherence.
Ongoing Care and Follow-Up
Post-viral chronic fatigue syndrome can include fatigue, fever, sore throat, painful lymph nodes, myalgias, arthralgias, sleep disturbance, and headache. Appropriate treatment and monitoring of group A streptococcal infection aims to prevent nonsuppurative complications such as acute rheumatic fever and glomerulonephritis, reduce toxic complications and local suppurative spread, limit transmission, and shorten illness duration. Sore throat can also precede broader constitutional symptoms that culminate in viral encephalitis.
Complications
Peritonsillar abscess can follow untreated streptococcal pharyngitis and presents with unilateral swelling and erythema and uvular deviation. Parapharyngeal infections can lead to airway obstruction, aspiration after intraoral rupture, jugular vein thrombophlebitis with pulmonary emboli, carotid artery erosion, and mediastinitis.
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