Respiratory System Infections

• Respiratory system infections are primary causes for medical attention and morbidity/mortality.
• They primarily affect children under 5 and adults over 65 due to weaker immune systems and vulnerable airways.

Common Infections

• Most commonly affect the upper respiratory tract, are mild, and self-limiting.
• Include acute pharyngoamigdalitis, laryngitis, rhinopharyngitis, sinusitis, acute otitis media, and otitis externa.
• Lower respiratory tract infections, like community-acquired pneumonia (NAC), COPD exacerbation, or acute bronchitis, occur less but have higher morbidity/mortality.

Pharyngoamigdalitis (Tonsillitis)

• It involves inflammation/infection of the pharynx and/or peritonsillar area, named pharyngoamigdalitis when tonsils are involved.
• Most acute pharyngoamigdalitis (FA) cases in adults are viral (80-90%) and do not require antibiotics.
• Bacterial FA cases are commonly caused by Streptococcus pyogenes.
• Diagnosis involves observing erythema, edema, exudates, vesicles, or ulcers.
• Viral etiology is suspected with conjunctivitis, common cold symptoms, rhinorrhea, hoarseness, or oral ulcers.
• Centor-McIsaac criteria help identify patients likely to have a streptococcal infection, assigning points for:
  • Fever above 38°C
  • Tonsillar swelling or exudate
  • Anterior cervical lymph node enlargement
  • Absence of cough
  • Age: 3-14 years (1 point), 15-44 (0 points), >45 years (-1 point)
• Probability based on points:
  • ≤0 points: 1-2.5% chance of S. pyogenes
  • 1 point: 5-10% chance
  • 2 points: 11-17% chance
  • 3 points: 28-35% chance
  • ≥4 points: 51-53% chance
• Microbiological tests (rapid strep test) are not indicated if ≤2 points are obtained.
• Rapid tests or throat culture is considered if ≥3 points are scored; antimicrobial treatment is then assessed.

Laryngitis

• Laryngitis, a common upper respiratory tract infection, presents with rhinorrhea, cough, and sore throat.
• Uncomplicated acute catarrhal laryngitis is a common clinical syndrome and does not require microbiological diagnosis, additional tests, or antibiotics, since its etiology is mainly viral (>90%).

Acute Otitis Media (AOM)

• AOM involves inflammation of the middle ear and tympanic membrane mucosa, often leading to effusion.
• 75-90% of AOM cases are self-limiting, resolving spontaneously in 7-10 days.
• It is common in children but less frequent in adults.
• Diagnosis is based on the presence of exudate and inflammation in the middle ear, with acute onset.
• Microbiological tests are generally not indicated, except in severe cases or treatment failure, when ear exudate culture with a sterile swab is performed, especially if the tympanic membrane is perforated.
• Antimicrobial treatment is unnecessary for AOM without severe symptoms.
• Antibiotics is considered if there's no improvement after 48-72 hours or if the patient has severe AOM (fever >39°C, intense ear pain).

Otitis Externa (OE)

• OE is inflammation of the skin covering the auricle, external auditory canal, and outer tympanic epithelial layer.
• Localized OE is termed circumscribed, while diffuse OE affects more extensive auricular soft tissues.
• Diffuse OE is diagnosed by pruritus, ear pain, discharge, complete canal occlusion, and tragus tenderness.
• Suspect malignancy with progressive facial and cranial soft tissue involvement and necrosis.
• Microbiological diagnosis may be performed via sterile swab sampling of ear exudate when necessary.
• Antimicrobial treatment is generally not indicated, but prescribed for diffuse OE without improvement after 48-72 hours or for circumscribed OE.

Sinusitis

• Sinusitis is an inflammatory condition affecting the mucosa of one or more paranasal sinuses.
• When nasal cavity inflammation accompanies it, it’s termed rinosinusitis.
• Most cases are viral (90-98%), often as secondary infections from common colds.
• After 7 days, bacterial infection probability increases, along with symptom intensity and severity.
• Diagnosis of bacterial sinusitis requires at least 2 major symptoms (purulent nasal discharge, postnasal drip, nasal congestion or obstruction, facial pain, or fever) or one major symptom and ≥2 minor symptoms (headache, ear pain, halitosis, dental pain, cough, fatigue).
• Other criteria include symptom persistence beyond 7-10 days without improvement, clinical worsening, or new fever episode, headache, or increased secretions after an upper respiratory tract infection, 5-6 days after initial improvement.
• Microbiological tests are not routinely indicated, only in severe cases with complications, where nasal and nasopharyngeal samples can be cultured via sinus aspiration or puncture, using a specific anaerobic container.
• Mild acute sinusitis does not require antimicrobial treatment.
• Acute sinusitis with intense symptoms lasting over 7-14 days or specific bacterial sinusitis signs would indicate antimicrobial treatment.

Community-Acquired Pneumonia (NAC)

• NAC is defined as lung parenchyma infection originating outside the hospital setting.
• Its symptoms include fever, variable respiratory symptoms, and pulmonary infiltrates on radiographs.
• It's a common cause of morbidity/mortality, especially in older adults and those with comorbidities.
• Typical NAC involves abrupt onset, high fever, pleuritic pain, lobar consolidation on X-ray, purulent sputum, and leukocytosis.
• Atypical NAC involves insidious onset, extrapulmonary symptoms, clinical-radiological dissociation, absent leukocytosis, and non-condensing, diffuse infiltrates.
• Diagnosis is made by identifying patient signs and symptoms such as fever lasting more than 4 days, dyspnea, tachypnea (>100 breaths per minute), crackles, and alveolar consolidation.
• Evaluation of respiratory rate, blood pressure, O2 saturation, and mental status should also be performed.
• Treatment should begin promptly, within 4 hours of diagnosis, to reduce 30-day mortality.
• To assess severity, the CURB-65 criteria are used, giving 1 point for each criterion:
  • Confusion
  • Uremia (>42 mg/dL)
  • Respiratory rate (≥30 rpm)
  • Low blood pressure (systolic ≤90 mmHg or diastolic ≤60 mmHg)
  • Age ≥65 years
• Based on the CURB-65 score:
  • Mild (CURB-65 ≤1): no hospitalization is needed
  • Moderate (CURB=2): hospitalization or 24-hour monitoring is needed
  • Severe (CURB ≥3): hospitalization is needed, and ICU admission necessity is evaluated
• If uremia determination is unavailable, the CRB-65 scale, assessing confusion, respiratory rate (≥30 rpm), low blood pressure (systolic ≤90 mmHg or diastolic ≤60 mmHg), and age ≥65, can be used.
• Based on the CRB-65 scale:
  • Low (CRB-65=0): outpatient treatment is needed
  • Moderate (CRB-65=1): patient requires hospital assessment and supervision
  • Severe (CRB≥2): patient requires hospitalization
• Microbiological tests aren't necessary for NAC cases not requiring hospital admission, except for epidemiological reasons or in immunocompromised patients after individual evaluation.
• Nasopharyngeal swabs for respiratory virus PCR, urine antigens for Legionella pneumophila and Streptococcus pneumoniae, and blood cultures are recommended
• Individualized samples include other tests.

Pneumonia in Institutionalized Patients

• Nursing homes are environments where respiratory infections are high risk.
• Institutionalized patient pneumonia presents certain differences from NAC or hospital-acquired pneumonias.
• Its prevalence ranges from 2.7-32%.
• Diagnosis is based on symptoms and signs that include productive/non-productive cough, dyspnea, tachypnea (>22 breaths/min), hypoxemia (oxygen saturation <90%), fever (>38°C), or hypothermia (<36°C) in the elderly.
• Atypical symptoms, such as sudden confusion/delirium, appetite loss, functional decline and/or drowsiness may be present.
• The differential diagnosis between this syndrome and common respiratory infections in institutionalized individuals is usually made via radiographic studies as symptoms are nonspecific.
• Microbiological diagnosis is usually not indicated.
• Sputum cultures, bronchoaspirates, and urinary antigens for L. pneumophila and S. pneumoniae are performed in indicated cases (immunocompromised patients, suspected resistant or atypical pathogens, or severe pneumonia).

Aspiration Pneumonia

• Aspiration pneumonia occurs via accidental entry of foreign material into the airways and is a common cause of treatment in institutionalized patients.
• Its clinical diagnosis depends on symptoms such as productive cough with purulent/foul-smelling sputum, fever/chills, dyspnea/tachypnea, pleuritic chest pain, and in severe cases, cyanosis and sepsis signs.
• Microbiological diagnosis is not indicated except in moderate to severe aspiration pneumonia or suspected multi-resistant bacteria infection.
• Blood cultures, sputum cultures, bronchial aspirates, and urine antigens for L. pneumophila and S. pneumoniae can be performed.

Exacerbation of COPD (A-EPOC)

• A-EPOC is a natural course of the disease with increased dyspnea and/or worsening cough/sputum, possibly with tachypnea/tachycardia, associated with increased local/systemic inflammation.
• Respiratory infection (viral or bacterial) is the most frequent disease aggravation, although non-infectious causes may contribute, such as exposure to air pollution, dust, vapors, or abandoned baseline medication.
• The A-EPOC diagnosis is mainly clinical, following symptom exacerbation.
• Severity criteria include severe cyanosis, altered consciousness, respiratory rate >25 rpm, heart rate >120 bpm, use of accessory respiratory muscles, ventilatory muscle failure signs, right heart failure signs, or failure to respond after initial treatment.
• Determining whether an exacerbation is infectious, particularly bacterial, is complex.
• Anthonisen criteria can estimate the likelihood of bacterial etiology, relies on:
  • increased dyspnea
  • sputum volume increase
  • increased sputum purulence.
• Antimicrobial treatment is indicated if 2-3 cardinal symptoms are met, or if one of 2 is the increase in sputum purulence.
• It is also indicated in severe COPD cases, regardless of symptom count.
• Microbiological tests are not systematically recommended; a Gram stain and sputum culture may be performed only in moderate/severe A-EPOC cases.

Acute Bronchitis

• Acute bronchitis involves inflammation of the bronchial mucous membrane and is usually self-limiting, with viral etiology in 95% of cases.
• Diagnosis is based on acute cough, initially dry, then productive, worsening at night, persisting for several weeks.
• Alarm signs that can lead to a diagnosis of a severe infection are dyspnea, tacypnea, chest pain, hemoptysis, severe worsening of general condition, with a high fever, tachycardia, and/or hypotension in patients with chronic underlying illness.
• Microbiological diagnosis is not typically advised unless specific situations are present (immunocompromised patients, with COPD or suspicions of bacterial etiology).
• Due to mostly viral etiology, routine antibiotic use is discouraged, only recommended in severe cases, in patients with comorbidities or in immunocompromised patients and when purulent sputum is present.
• Isolated sputum does not indicate antibiotic treatment in previously healthy patients without focal thoracic signs on examination.

Sampling

• For pharyngeal exudate samples, the swab must roll over the pharynx and tonsils, ensuring to exclude the tongue and mouth’s walls.
• The swab is placed in transport media and sent to the lab for culture or used in a rapid test device.
• Sputum should be collected after deep expectoration, preferably in the morning, after rinsing the mouth with water.
• Induced with aerosolized sterile saline at 37°C, if deep expectoration won't occur.
• Samples should exclude saliva, as it contaminates sputum with oral flora and affects processing validity.
• The specimen must be collected in sterile, wide-mouth containers and kept refrigerated during storage and shipping.

Empirical Treatment Tables

• Empirical treatment options are provided for various respiratory infections, detailing drug choices, dosages, durations, and adjustments for renal/hepatic insufficiency.

Directed Treatment Methods

• Once microbiological results are available, select the most appropriate antimicrobial with a high probability of success.
• It is crucial to simplify antimicrobial treatment when possible and select the least broad-spectrum antimicrobial.
• Prescribing either amoxicillin or oral penicillin V should be considered first for infections of the upper respiratory tract when the etiological agent is sensitive to penicillins.
• Indicating oral amoxicillin/clavulanate could be a plan B if the agent isn’t susceptible to penicillins, but only after a failure to yield better results after 48–72 hours of starting first-line treatment and/or a multiresistant/poly-microorganism is recognized rather than using other broad-spectrum alternatives.
• In patients with lesser respiratory tract infections, it is recommended to use amoxicillin/clavulanate only after assurance of isolation of S. pneumoniae being penicillin-susceptible or when it's clavulanate based, depending on the level of security when linked by other alternatives. It would be recommended to use oral cefadroxil when Staphylococcus aureus is isolated or even utilize trimethoprim sulfamethoxazole (cotrimoxazole) or clindamycin if oxazoline-resistant (meticillin). For patients suffering from Mycoplasma peneumoniae or Clamydophyla peneumophila, azithromycin or clarithromycin can be used. Quinolones are indicated in cases such as Legionella pneumophila or Pseudomonas aeruginosa , or in situations of resistant.
• Try to restrict quinolones at all times because of their relationship with incapacitating adverse effects, potentially permeant second reactions linked to it, and mental problems caused for quinolones.
• Exercise care when using the product around patients who have the extension of the QT.

Keys to Concepts

• Treatment guidelines are given for:
  • Acute tonsillitis, in most cases of having viral origins, may not require any type of antibiotics, only being indicated for S. Pyrogens.
  • Acute otitis media (AOM), frequently is an infection. If it isn't improved, amoxicillin clavulanate is administered.
  • For otitis externa (OE) the only way to treat it is through antimicrobial medication.
  • In the greatest amount of cases from Sinusitis, the etiology is purely viral. Consider oral amoxicillin to treat this.
  • With acute community acquired pneumonia (NAC) it may bring higher health and mortality risks, frequently for older adults. With a bacteria known to caused harm, the fast prescription with antibiotics can improve the state, and the go-to for medical care should always have clavulanic amoxicillin.
  • AEPC shows difficulty due to it's etiology with Anthonisen being necessary.
  • Bronchitis being frequent, it's treatment is to only focus on serious cases where antibiotics should be focused.