S. aureus infection can preclude patients to a wide range of infectious processes. Therefore, a thorough multisystem history and physical should be performed. When evaluating the need for hospitalization of the patient, care should be taken to assess the onset of symptoms, duration of symptoms, as well as associative symptoms of fever, chills, dyspnea, or productive cough. Eighty percent of patients with pneumonia can be febrile. However, this finding is less reliable in the elderly. Evaluation for sick contacts, recent travel, ongoing or recent infection with influenza can also help delineate those who may have a higher predisposition to developing S. aureus pneumonia. Employment status and recent hospitalizations can be ascertained to raise clinical suspicion for colonization with S. aureus, such as healthcare workers.

In the appropriate clinical scenario, evaluation for IV drug use should be ascertained as tricuspid valve endocarditis from IV drug use can lead to septic emboli to the lungs and cause S. aureus pneumonia. Physical exam should include a complete multisystem evaluation, but the focus should be given to the cardiopulmonary examination to assess for signs of valvular murmur, respiratory distress, tachypnea, or inspiratory crackles in a lobar pattern. Percussion and tactile fremitus can also be utilized if there is a concern for pleural effusion. Unfortunately, there is no specific constellation of history and physical exam findings that can effectively guarantee with certainty a diagnosis of pneumonia, but the above findings do further the clinical suspicion of this disease process.[7]

Initial evaluation for staphylococcal pneumonia starts with the same foundational workup for those suspected of having any etiology of CAP. A complete blood count (CBC) will likely show leukocytosis with a neutrophilic predominance. The gold standard for diagnosing pneumonia with the appropriate clinical suspicion is the presence of infiltrate on a chest radiograph.[8] The infiltrate on a chest radiograph can show lobar infiltrate or in severe patients can show cavitary lesions and empyema. If the clinical syndrome supports the diagnosis of pneumonia, but the chest radiograph does not reveal pathology, a computed tomography (CT) scan can be performed to further evaluate for pathology in the lungs.

Findings on CT scan may show a developing lobar infiltrate or cavitary lesion that chest radiograph may not reveal.[9] A sputum sample can be obtained, but a 2005 study noted that only 17% of the study population were able to produce an adequate sample. However, if the patient can produce an adequate sample, 82% were found to be diagnostic and could be used to guide antibiotic therapy.[10] An MRSA swab may also be utilized to assess the patient's colonization status for MRSA and, therefore, further the suspicion of this process. A procalcitonin level can also be drawn at the time of treatment in order to guide antibiotic efficacy and aid in antibiotic stewardship.[11]

Treatment for staphylococcal pneumonia depends on if this process is categorized into either MRSA or MSSA. If MRSA is suspected or confirmed, either vancomycin or linezolid should be initiated at the start of treatment and be promptly discontinued if MRSA is ruled out. Both vancomycin and linezolid have similar efficacy, and selection should be based on patient tolerance, antibiotic allergy profile, renal function, drug interaction, and intravenous access. As linezolid is systemically bioavailable in its oral form, this is preferred if there is an issue with intravenous access. Vancomycin is preferred if the patient is cytopenic or taking selective serotonin reuptake inhibitors (SSRIs).[12][13] Ceftaroline can be used if vancomycin or linezolid are contraindicated; however, it should be known that it is not FDA approved for hospital-acquired pneumonia or ventilator-associated pneumonia. Clindamycin is also an alternative, but it is also less efficacious in hospital-acquired and ventilator-associated pneumonia.[14] 

If culture results grow MSSA and rule out other causes of pneumonia, then therapy can be de-escalated to nafcillin, oxacillin, or cefazolin.[15] Supportive measures for staphylococcal pneumonia include bronchodilation to help those with underlying lung diseases such as asthma or chronic obstructive pulmonary disease (COPD). Supplemental oxygenation may also be needed due to the restrictive lung disease caused by the pneumonia disease process. This can begin with a nasal cannula. However, if the disease process is severe enough, then mechanical ventilation may be necessary.

As the clinical presentation for pneumonia and, therefore, staphylococcal pneumonia is broad and nonspecific, so is the differential for this process. Differential diagnosis may include:

• Pneumonia secondary to:
• Streptococcal pneumonia 
• Nontypeable Haemophilus influenza 
• Mycoplasma pneumonia 
• Chlamydia pneumonia 
• Legionella 
• Gram-negative bacilli 
• Group A Streptococcus 
• Anaerobic infection 
• Mycoplasma tuberculosis 
• Viral infection 
• Pulmonary edema secondary to congestive heart failure 
• Pulmonary hemorrhage 
• Atelectasis 
• Pneumonitis from aspiration or chemical exposure 
• Interstitial lung disease 
• Drug reaction 
• Pulmonary embolism

Prognosis of staphylococcal pneumonia is very much dependent on the patient's comorbid conditions, underlying lung disease, and sequelae of this disease process. Prognosis is more guarded if the patient becomes bacteremic, and this further alludes to the importance of astute clinical suspicion and appropriate antibiotic intervention.

A significant complication of staphylococcal pneumonia is the development of severe necrotizing pneumonia. This can be seen in community associated-MRSA (CA-MRSA).[16] If this is of clinical concern, then a chest CT may be warranted to help further assess for this pathology. It should be noted that a chest CT should not be used in the initial diagnosis of pneumonia, and that chest x-ray should be ordered first as a foundational approach to the initial evaluation of pneumonia. Staphylococcal pneumonia may also lead to complications such as sepsis, septic shock, bacteremia, and respiratory failure leading to invasive mechanical ventilation.

Patients should be educated on the presentation of CAP in the outpatient setting, as this could lead to a faster diagnosis of CAP and possibly staphylococcal pneumonia in the appropriate clinical scenario. This is important for patients to be educated on, as prompt antibiotic therapy can help resolve this infectious process before sequelae such as sepsis, bacteremia, or respiratory failure occur.

Clinicians need to have an interprofessional team approach to the diagnosis and treatment of these patients. There should be a broad clinical suspicion with this and any presentation of patients with pneumonia. Nursing staff should also have a broad suspicion as they are foundational to patient care and help add information that the patient may not have alluded to during the initial encounter. Pharmacy staff should also be utilized to their fullest potential as antibiotic therapy and stewardship are essential to practice to help not only treat this disease process but also prevent antibiotic resistance in the future.