Atypical pneumonia

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

For patients presenting with respiratory tract infection symptoms such as fever and cough, clinicians should begin by considering current seasonal and local epidemiologic trends to inform their differential diagnoses, such as COVID-19 during SARS-CoV-2 surges and influenza, respiratory syncytial virus, and other respiratory viruses during winter respiratory viral seasons. See topics Coronavirus disease 2019 (COVID-19), Influenza infection, and Respiratory syncytial virus infection.

Initial treatment for any patient with pneumonia is guided by the severity of the disease and presence of comorbidities, prior hospitalizations, the presence of any rapid diagnostic results suggesting a treatable viral pathogen, and any known bacterial resistance in the community (i.e., penicillin resistance or macrolide resistant Streptococcus pneumoniae)[18] In severe community-acquired pneumonia, guidelines recommend empiric treatment with a beta-lactam antibiotic, as well as coverage for atypical pathogens.[18][44] Antibiotic treatment should be directed at the causative organism once etiology is established.

Patients should be assessed for hydration status, hemodynamic stability and adequacy of gas exchange. [ ]

Antibiotic therapy

Atypical bacterial pneumonia pathogens generally do not respond to beta-lactam antibiotics and require treatment with a macrolide, tetracycline, or fluoroquinolone. The current pneumonia treatment guidelines recommend considering empiric use of a macrolide or doxycycline for uncomplicated community-acquired pneumonia to ensure coverage of atypical organisms.[18][44][45][46] [ ] Coverage of atypical organisms is also recommended in more severe disease and patients with comorbidities.[18][44][47] The recommendation to cover atypical pathogens in the empiric antibiotic regimen is debated;[48][49][50] however, the recommendation is supported by current data.[51][52]

Tetracyclines and fluoroquinolones are generally not recommended in children or pregnant women; however, their use may be considered in these patients when the benefits of using these drugs outweigh the risks, and there are no other suitable treatment options available, especially in cases of macrolide resistance.

When a specific etiology for the pneumonia is found using a reliable method, antimicrobial therapy should be directed at that pathogen.[18] However, in the last few years an increasing frequency (up to 80%) of macrolide-resistant Mycoplasma pneumoniae cases have been reported in Asia, whereas rates are lower in the Middle East (30%), Europe (10%), and the US (10%).[53][54][55][56][57][58] This is likely due to overuse of macrolides for the treatment of community-acquired pneumonia. Fluoroquinolones are highly effective for macrolide-resistant strains of M pneumoniae.[59][60] When Legionella pneumophila is diagnosed, either macrolides or fluoroquinolones should be used without preference to any of the agents.[61]

The use of procalcitonin (a biomarker) to guide initiation, duration, and de-escalation of antibiotic treatment has been found to result in a lower risk of mortality, lower antibiotic consumption, and lower risk of side effects in patients with acute respiratory infections.[62][63] However, one review found no difference in short-term mortality in critically ill patients specifically, while another study found that procalcitonin-guided therapy did not result in decreased use of antibiotics in patients with suspected lower respiratory tract infection.[64][65]

Outpatient care or hospitalization

Scoring the severity of illness can help to determine whether the patient can be treated as an outpatient or requires hospitalization or intensive care. It is most commonly determined using the Pneumonia Severity Index (PSI).[66] [ Community-acquired pneumonia severity index (PSI) for adults Opens in new window ] The PSI, also referred to as the Pneumonia Patient Outcomes Research Team Model, has been repurposed as an online tool. Twenty factors are assessed, including age, respiratory rate, pulse, blood pressure, and temperature, and total points are added together. CURB-65 is another severity scoring system developed by the British Thoracic Society.[44] [ CURB-65 pneumonia severity score Opens in new window ]

New scoring systems might have some advantage on the PSI and the CURB-65, in identifying patients who need intensive care and hospital admission.[67][68][69][70] Two studies suggest that saturation below 92% is associated with adverse effects and more severe disease, thus requiring admission.[69][71]

Role of corticosteroids (non-COVID-19)

The use of corticosteroids in patients with severe community-acquired pneumonia has been a long-debated issue. Current guidelines generally recommend against the use of corticosteroids in patients with nonsevere community-acquired pneumonia. This recommendation is based on the fact that there are no data suggesting benefit in patients with nonsevere community-acquired pneumonia, or influenza pneumonia, with respect to mortality or organ failure, and only limited data to support their use in patients with severe community-acquired pneumonia.[18] However, Surviving Sepsis Campaign guidelines acknowledge that they may be considered in patients with refractory septic shock and an ongoing requirement for vasopressor therapy.[72]

Meta-analyses of studies of hospitalized adults with community-acquired pneumonia found that the use of corticosteroids was associated with reduced need for mechanical ventilation, reduced hospital stay, lower clinical failure rates, fewer complications (including septic shock), decreased C-reactive protein (CRP) levels, and reduced all-cause mortality. However, it appears that the reduction in mortality applies only to patients with severe community-acquired pneumonia. In patients with nonsevere disease, adjunctive corticosteroids reduce morbidity, but not mortality.[73][74][75][76][77][78][79]

A study from Japan suggests that corticosteroids may not offer any advantage in the treatment of M pneumoniae pneumonia.[80] However, adjunct corticosteroid therapy has been found to significantly reduce the duration of fever, length of hospital stay, and decreased CRP levels in patients with macrolide-refractory M pneumoniae.[81]

Patients treated with corticosteroids have an increased risk for hyperglycemia.[75][76] Other adverse effects include super infection and upper gastrointestinal bleeding.

Adjunctive corticosteroid therapy has not been studied in pregnant or pediatric populations and cannot currently be recommended.

Safety of fluoroquinolone antibiotics

Systemic fluoroquinolone antibiotics may cause serious, disabling, and potentially long-lasting or irreversible adverse events. This includes, but is not limited to, tendinopathy/tendon rupture; peripheral neuropathy; arthropathy/arthralgia; aortic aneurysm and dissection; heart valve regurgitation; dysglycemia; and central nervous system effects including seizures, depression, psychosis, and suicidal thoughts and behavior.[82]

Prescribing restrictions apply to the use of fluoroquinolones, and these restrictions may vary between countries. In general, fluoroquinolones should be restricted for use in serious, life-threatening bacterial infections only. Some regulatory agencies may also recommend that they must only be used in situations where other antibiotics, that are commonly recommended for the infection, are inappropriate (e.g., resistance, contraindications, treatment failure, unavailability).
Consult your local guidelines and drug formulary for more information on suitability, contraindications, and precautions.

Tracheal intubation: animated demonstration

How to insert a tracheal tube in an adult using a laryngoscope.

Bag-valve-mask ventilation: animated demonstration

How to use bag-valve-mask apparatus to deliver ventilatory support to adults. Video demonstrates the two-person technique.

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