PneumoniaDEFINATION OF

DIFFERENT TYPES OF PNEUMONIADr. Jaydeep HirparaAssistant Professor,

Department Of Medicine,Govt. Medical College, Surat

Pneumonia vs PneumonitisPneumonitis (noo-moe-NIE-tis) is a general term that refers

to inflammation of lung tissue. Although pneumonia is technically a type of pneumonitis because the infection causes inflammation, most doctors are referring to other causes of lung inflammation when they use the term "pneumonitis." 

Pneumonia can be generally defined as inflammation of the lung parenchyma, in which consolidation of the affected part and a filling of the alveolar air spaces with exudate, inflammatory cells, and fibrin is characteristic.[1] Infection by bacteria or viruses is the most common cause, although inhalation of chemicals, trauma to the chest wall, or infection by other infectious agents such as rickettsiae, fungi, and yeasts may occur.

Community-acquired pneumonia (CAP) CAP is defined as pneumonia that develops in the

outpatient setting or within 48 hours of admission to a hospital. CAP should not meet the criteria for healthcare-associated pneumonia (HCAP).

Typical & Atypical - In the individual patient, there are no findings from history, physical examination, or routine laboratory studies that allow the clinician to distinguish pneumonia caused by atypical from typical organisms. Indeed, the term "atypical pneumonia" should no longer be used.

The IDSA defines CAP as “an acute infection of the pulmonary parenchyma that is associated with at least some symptoms of acute infection, accompanied by the presence of an acute infiltrate on a chest radiograph or auscultatory findings consistent with pneumonia (such as altered breath sounds and/or localized rales), in a patient not hospitalized or residing in a long-term care facility for more than 14 days before onset of symptoms

Typical vs Atypical CAPBacteria are the most common cause of CAP and

have traditionally been divided into two groups: "typical" and "atypical" agents:

"Typical" organisms include S. pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Group A streptococci, Moraxella catarrhalis, anaerobes, and aerobic gram-negative bacteria.

"Atypical" refers to pneumonia caused by Legionella spp, Mycoplasma pneumoniae, Chlamydophila (formerly Chlamydia) pneumoniae, and C. psittaci.

Hospital-acquired (or nosocomial) pneumonia (HAP) Pneumonia that occurs 48 hours or more

after admission and did not appear to be incubating at the time of admission.

Early vs Late onsetThe ATS subdivides nosocomial pneumonia

into early onset (usually within the first 4 d of the hospitalization) and late onset (usually occurring after the fifth hospital day). Early onset nosocomial pneumonia tends to carry a better prognosis than does late-onset nosocomial pneumonia; the latter tends to be associated with multidrug-resistant organisms and so is characterized by higher mortality rates

Ventilator-associated pneumonia (VAP) A type of HAP that develops more than 48 to

72 hours after endotracheal intubation.

Healthcare-associated pneumonia (HCAP) Pneumonia that occurs in a non-hospitalized

patient with extensive healthcare contact, as defined by one or more of the following:

      - Intravenous therapy, wound care, or intravenous chemotherapy within the prior 30 days

      - Residence in a nursing home or other long-term care facility

     - Hospitalization in an acute care hospital for two or more days within the prior 90 days

      - Attendance at a hospital or hemodialysis clinic within the prior 30 days

Aspiration PneumoniaAspiration is defined as the inhalation of either

oropharyngeal or gastric contents into the lower airways; that is, the act of taking foreign material into the lungs.

Three types of material cause 3 different pneumonic syndromes. Aspiration of gastric acid causes chemical pneumonia, which has also been called aspiration pneumonitis (Mendelson's syndrome)—although the former is an infectious process and the latter is a chemical injury, and both are managed differently.[1] Aspiration of bacteria from oral and pharyngeal areas causes bacterial pneumonia, and aspiration of oil (eg, mineral oil or vegetable oil) causes exogenous lipoid pneumonia, a rare form of pneumonia. In addition, aspiration of a foreign body may cause an acute respiratory emergency and, in some cases, may predispose the patient to bacterial pneumonia.

Risk Factors for Multidrug-Resistant Pathogens Causing Hospital-Acquired Pneumonia, Healthcare-Associated Pneumonia, and Ventilator-Associated PneumoniaAntimicrobial therapy in preceding 90 days Current hospitalization of 5 days or more High frequency of antibiotic resistance in the community

or in the specific hospital unit Presence of risk factors for HCAP:    Hospitalization for 2

or more days in the preceding 90 days    Residence in a nursing home or extended care facility    Home infusion therapy (including antibiotics)    Chronic dialysis within 30 days    Home wound care    Family member with multidrug-resistant pathogenImmunosuppressive disease and/or therapy

Additional Risk Factors for Multidrug-Resistant Infections in Healthcare-Associated Pneumonia

Presence of chronic indwelling device Prior antibiotic use in the last 3 months Chronic and advanced pulmonary diseases

(chronic obstructive pulmonary disease, bronchiectasis, etc.)

History of alcoholism and immunosuppression (i.e., systemic corticosteroids, immunosuppressive therapy, etc.)

Hypersensitivity pneumonitis (HP) (Extrinsic allergic alveolitis)DIAGNOSTIC CRITERIA — Several different diagnostic criteria

for HP have been proposed [9,11,12]. All have significant problems that limit their utility:

 • All were developed before the common use of high resolution CT scanning and bronchoalveolar lavage

 • Most apply only to typical, acute cases

 • No clear diagnostic criteria exist for subacute or chronic disease

 • All rely on the presence of an abnormal chest radiograph or positive serum precipitins, findings which are often absent

The proposed diagnostic criteria for HP are based upon the presence of some or all of the following :

 1. Known exposure to offending antigen(s) identified by: A. History of appropriate exposure. B. Aerobiologic or microbiologic investigations of the environment that

confirm the presence of an inciting antigen .C. The presence of specific IgG antibodies in serum against the identified

antigen (serum precipitins). A positive precipitin test even in the presence of a clear history of exposure to the identified antigen is merely suggestive of, rather than diagnostic of, a potential etiology.

 2. Compatible clinical, radiographic, or physiologic findings: A. Respiratory (± constitutional) symptoms and signs, such as crackles on

chest exam, weight loss, cough, breathlessness, febrile episodes, wheezing, and fatigue. These findings are especially suggestive if present, appearing, or worsening several hours after antigen exposure [15].

B. Reticular, nodular, or ground glass opacity on chest radiograph or HRCT .

C. Altered spirometry and/or lung volumes (may be restrictive, obstructive, or mixed pattern), reduced DLCO, altered gas exchange either at rest or with exercise testing

3. BAL with lymphocytosis:

A. Usually with low CD4 to CD8 ratioB. Positive specific immune response to the antigen by

lymphocyte transformation testing (currently not available in most centers)

4. Positive inhalation challenge testing by:

A. Reexposure to the environment (figure 1)

 B. Inhalation challenge to the suspected antigen in a hospital setting (figure 2)

5. Histopathology showing compatible changes:

A. Poorly formed, noncaseating granulomas ORB. Mononuclear cell infiltrate

Definite HP Definite HP — A patient is considered to have definite HP under the

following circumstances:

 • Criteria 1, 2, and 3 are met — Histopathologic confirmation of the diagnosis is not needed in the majority of such cases.

 • Criteria 1, 2, and 4A are met — BAL or histopathologic confirmation of the diagnosis is not needed in the majority of these cases but may be important to allow decision-making regarding management.

 • Criteria 1, 2A, 3, and 5 are met — These patients are usually identified as part of a case cluster. The index cases usually have more severe disease.

 • Criteria 2, 3, and 5 are met — In these cases, the diagnosis is first suspected after BAL or transbronchial lung biopsy. It is critical that every attempt be made to identify the specific antigen. This often requires aggressive surveillance of the home and work environment by an experienced industrial hygienist. Complete removal of the patient from his or her usual environment for two to three weeks may lead to spontaneous improvement, and reexposure may result in acute symptoms that help identify environmental precipitants.

Probable or subclinical HPProbable or subclinical HP — A patient is

considered to have probable HP if criteria 1, 2A, and 3 are present, and subclinical HP if criteria 1 and 3A are present. Sensitization, rather than HP, is present in patients who only fulfill criterion 1.

Acute eosinophilic pneumoniaAEP is a diagnosis of exclusion that requires :

An acute febrile illness of short duration (usually less than one week)

Hypoxemic respiratory failureDiffuse pulmonary opacities on chest radiographBAL eosinophilia >25 percentLung biopsy evidence of eosinophilic infiltrates (acute

and/or organizing diffuse alveolar damage (DAD) with prominent eosinophilia is the most characteristic finding)

Absence of known causes of eosinophilic pneumonia, including drugs, infections, asthma, or atopic disease

A 55 year old male presents to his primary care physician's office with cough, mild dyspnea, and fever to 101 degrees. Symptoms have been present for the past 3 days, and when over-the-counter cold medications were having no effect, he decided to seek medical attention. On initial examination, blood pressure was 120/73, pulse was 96 and regular, and respirations were 20. He was febrile with a temperature of 100.9 degrees. Lung examination revealed the presence of right lower lung crackles with decreased breath sounds in this area as well.

Laboratory studies revealed WBC of 15.6 with a left shift, sodium of 140, potassium of 4.5, BUN of 22 and creatinine of 1.0. Chest x-ray revealed a right lower lobe infiltrate.

Based upon the above presentation, what is the most appropriate course of action?

A. Admit the patient to the hospital and start intravenous ceftriaxone and azithromycin

B. Admit the patient to the hospital and start intravenous cefipimeC. Prescribe clarithromycin, 500 mg twice daily and schedule a

follow-up in 1 weekD. Refer the patient to a pulmonary specialist for a STAT evaluation

ANSWER: CThis patient obviously has pneumonia, and

according to the lack of recent hospitalization or exposure to a medical facility, it is acceptable to consider him as having community-acquired pneumonia. Based upon the presentation described, the patient does not have severe enough illness to necessitate admission to the hospital. Scales such as the Pneumonia Severity Index (PSI) can be used to judge if admission is necessary, in addition to the clinical impression of the practitioner. In this case, based upon the information provided, the patient can be allowed to go home and start oral antibiotics, and then re-evaluated to see if he is improving. Lack of improvement at the follow-up visit would be an indication for hospitalization, as would deterioration while being treated.

A 77 year old female presents to the emergency department with dyspnea, fever to 103, hypotension and mental status changes. Initial evaluation demonstrates a left lower lobe infiltrate. Additional studies show blood pressure of 90/60, respiratory rate of 34, and pulse of 110. Laboratory parameters include WBC of 2.3, and BUN of 33, with creatinine of 1.3. Pulse oximetry reveals 88% on room air, which comes up to 99% on 4 liters.

Based upon the above presentation, which of the following is the most appropriate course of action?

A. Discharge the patient on oral azithromycinB. Admit the patient to the general medical ward and begin

intravenous doxycycline and azithromycinC. Admit the patient to the intensive care unit, and begin

fluid resuscitation, and intravenous ampicillin-sulbactam and levofloxacin

D. Admit the patient to the intensive care unit and initiate mechanical ventilation, pressors, and intravenous piperacillin-tazobactam

ANSWER: CThis patient clearly has severe CAP, and

according to current recommendations, meets criteria for ICU admission for CAP. Specifically, the leukopenia, hypoxia, hypotension, and mild uremia all indicate the need for closer monitoring. Initial treatment for CAP requiring ICU admission includes empiric therapy with a beta-lactam + either azithromycin or a fluoroquinolone. If pseudomonas is suspected, an antipseudomonal, antipneumococcal beta-lactam is indicated, in addition to a quinolone. Other regimens may be used as well.

Persistent Pneumonia Symptoms in a 29-Year-Old

A 29-year-old, previously healthy woman was seen on 3 occasions by her primary care provider for upper respiratory symptoms 2 weeks after competing in an outdoor obstacle course that involved crawling in the dirt in the California San Joaquin Valley. The patient denies any recent sick contacts or travel outside of the local area. A diagnosis of community-acquired pneumonia was made and she was given 3 separate courses of antibiotics, over the course of 6-8 weeks, without improvement. She has presented to the urgent care clinic today with worsening cough, production of malodorous sputum, anorexia, fevers, chills, sweats, nausea, vomiting, and malaise. She has lost 20 lb since the onset of symptoms.

On physical examination, the patient is mildly ill-appearing, with a temperature of 102.4°F, a heart rate of 106 bpm, a respiratory rate of 22 breaths/min, a blood pressure of 118/64 mm Hg, and an oxygen saturation of 95% on room air. Lung auscultation reveals coarse rhonchi in the left upper lung field. Her heart rate is rapid, but no murmurs are appreciated. The remainder of her physical examination is unremarkable.

Laboratory tests performed in the urgent care clinic show a mild leukocytosis of 13.4 x 103/µL WBC count, with otherwise normal results. Chest radiography shows a 4.2-cm diameter cavitary lesion with an air fluid level in the left upper lobe, along with mediastinal lymphadenopathy (see Images 1-2).

What is the diagnosis? How would you approach this patient's treatment?

The patient was admitted to the hospital with respiratory isolation, aggressively hydrated with 4 L of normal saline, and started on intravenous ceftriaxone and azithromycin and 800 mg of oral fluconazole. Her purified protein derivative (PPD) and HIV test results were negative. Three induced sputum samples were negative for acid-fast bacilli. Within 1 day of treatment, she improved clinically and was discharged on oral fluconazole (800 mg daily) and amoxicillin/clavulanate (875/125 mg twice daily) with an empiric diagnosis of coccidioidomycosis. On reevaluation, she had almost complete resolution of her systemic symptoms. Within 3 months of therapy on fluconazole, she was asymptomatic and her cavitary lesion had resolved with mild residual scarring.

Coccidioidomycosis, commonly referred to as "valley fever" or "San Joaquin Valley fever," is a fungal infection caused by the inhalation of the spores of Coccidioides immitis, a fungus endemic to the semi-arid areas of the southwest United States, particularly central California, Arizona, parts of Texas, and Mexico.

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