Pneumocystis jirovecii/Pneumocystis Pneumonia (PCP)

Pneumocystis jirovecii is a yeast-like fungus causing pneumocystis pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia (PCP) in immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship. Pneumocystis pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia is spread through airborne transmission and classically affects patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with AIDS AIDS Chronic HIV infection and depletion of CD4 cells eventually results in acquired immunodeficiency syndrome (AIDS), which can be diagnosed by the presence of certain opportunistic diseases called AIDS-defining conditions. These conditions include a wide spectrum of bacterial, viral, fungal, and parasitic infections as well as several malignancies and generalized conditions. HIV Infection and AIDS, functioning as an AIDS-defining illness. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship may present with insidious onset of fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, chills Chills The sudden sensation of being cold. It may be accompanied by shivering. Fever, dry cough Dry Cough Strongyloidiasis, chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, and shortness of breath Shortness of breath Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea. The diagnosis is supported by an increased β-D-glucan level and diffuse, bilateral infiltrates on chest imaging in the immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis patient. A definitive diagnosis can be given with microscopy of induced sputum or specimens from bronchoalveolar lavage Bronchoalveolar lavage Washing out of the lungs with saline or mucolytic agents for diagnostic or therapeutic purposes. It is very useful in the diagnosis of diffuse pulmonary infiltrates in immunosuppressed patients. Pulmonary Fibrosis (BAL). Management involves antimicrobial therapy with a trimethoprim-sulfamethoxazole combination, and supportive care. Addressing the etiology of immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome is paramount. Prophylaxis Prophylaxis Cephalosporins is often required to prevent infection or reinfection.

Last updated: May 10, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

General Characteristics

Basic features of Pneumocystis

Pneumocystis is a yeast-like fungus. 

  • Previously classified as a protozoan
  • Isolated in host alveolar spaces 
  • Cell wall Cell wall The outermost layer of a cell in most plants; bacteria; fungi; and algae. The cell wall is usually a rigid structure that lies external to the cell membrane, and provides a protective barrier against physical or chemical agents. Cell Types: Eukaryotic versus Prokaryotic consists of carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates rich in: 
    • β-1,3-glucan
    • Chitins
    • Proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis
  • Reproduction:
  • Forms:
    • Trophic form: 
      • Mononuclear
      • Pleomorphic Pleomorphic Bacteroides
      • Thin walled
      • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables size
      • Pseudohyphal structures
      • Predominant form during active infection
    • Cyst form ( spore Spore The reproductive elements of lower organisms, such as bacteria; fungi; and cryptogamic plants. Microsporidia/Microsporidiosis form):
      • Contains 8 intracystic bodies
      • Thick walled with an outer membrane
      • Allows survival outside the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy
      • Releases trophic forms once matured
Photomicrograph pneumocystis jirovecii pneumonia

Photomicrograph of a toluidine blue-stained, lung-tissue impression showing numerous Pneumocystis jirovecii fungal cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change

Image: “This photomicrograph of a toluidine blue stained lung tissue impression smear, revealed the presence of numerous, Pneumocystis jirovecii, formerly known as Pneumocystis carinii, fungal cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change.” by CDC. License: Public Domain

Clinically relevant species

P. jirovecii (formerly known as P. carinii) causes pneumocystis pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia (PCP).

Epidemiology and Pathogenesis

Epidemiology

  • Rare amongst immunocompetent individuals
  • Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency varies depending on patient risk factors, but is generally < 5% in immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship:
    • Closer to 6% in solid-organ transplant recipients 
    • < 1% in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with hematologic malignancy Malignancy Hemothorax or HIV HIV Anti-HIV Drugs
    • Rate is declining in the United States due to prophylactic measures.

Reservoir Reservoir Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (disease vectors) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks. Humans may serve both as disease reservoirs and carriers. Escherichia coli

The reservoir Reservoir Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (disease vectors) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks. Humans may serve both as disease reservoirs and carriers. Escherichia coli for P. jirovecii is unknown, but immunocompetent humans may play a role.

Transmission

P. jirovecii spreads through airborne transmission.

Host risk factors

Pneumocystis pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia occurs in immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis individuals:

  • HIV HIV Anti-HIV Drugs with CD4 count < 200 cells/μL (an AIDS-defining condition)
  • Impaired cellular immunity Cellular immunity Manifestations of the immune response which are mediated by antigen-sensitized T-lymphocytes via lymphokines or direct cytotoxicity. This takes place in the absence of circulating antibody or where antibody plays a subordinate role. Squamous Cell Carcinoma (SCC)
  • Organ transplantation Organ Transplantation Transplantation is a procedure that involves the removal of an organ or living tissue and placing it into a different part of the body or into a different person. Organ transplantations have become the therapeutic option of choice for many individuals with end-stage organ failure. Organ Transplantation
  • Immunosuppressive therapy
  • Hematologic malignancies

Virulence factors Virulence factors Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: toxins, biological and surface adhesion molecules that affect the ability of the microorganism to invade and colonize a host. Haemophilus

  • Major surface glycoprotein (MSG) or glycoprotein A:
    • Main surface antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination
    • MSG locus Locus Specific regions that are mapped within a genome. Genetic loci are usually identified with a shorthand notation that indicates the chromosome number and the position of a specific band along the P or Q arm of the chromosome where they are found. For example the locus 6p21 is found within band 21 of the P-arm of chromosome 6. Many well known genetic loci are also known by common names that are associated with a genetic function or hereditary disease. Basic Terms of Genetics can undergo recombination Recombination Production of new arrangements of DNA by various mechanisms such as assortment and segregation, crossing over; gene conversion; genetic transformation; genetic conjugation; genetic transduction; or mixed infection of viruses. Virology to avoid host defenses.
    • Binds to:
      •   Surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS) protein D (protein within lung collagen Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth). Connective Tissue: Histology) of the host
      •   Macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation of the host
  • Biofilm Biofilm Encrustations formed from microbes (bacteria, algae, fungi, plankton, or protozoa) embedded in an extracellular polymeric substance matrix that is secreted by the microbes. They occur on body surfaces such as teeth (dental deposits); inanimate objects, and bodies of water. Biofilms are prevented from forming by treating surfaces with dentifrices; disinfectants; anti-infective agents; and anti-fouling agents. Staphylococcus formation provides a survival advantage.

Pathophysiology

  • P. jirovecii is inhaled into the alveolar space → trophic form attaches to alveolar epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology
  • Both humoral and cell-mediated immunity Cell-mediated immunity Manifestations of the immune response which are mediated by antigen-sensitized T-lymphocytes via lymphokines or direct cytotoxicity. This takes place in the absence of circulating antibody or where antibody plays a subordinate role. Squamous Cell Carcinoma (SCC) are essential to host defense:
    • CD4 lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes: Histology are the principal regulator of the host response.
    • Immunocompetent individuals can eradicate the organism or become colonized.
    • In patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with impaired cell-mediated immunity Cell-mediated immunity Manifestations of the immune response which are mediated by antigen-sensitized T-lymphocytes via lymphokines or direct cytotoxicity. This takes place in the absence of circulating antibody or where antibody plays a subordinate role. Squamous Cell Carcinoma (SCC):
      • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship cannot adequately clear the infection.
      • Inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation → alveolar damage → impaired gas exchange Gas exchange Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood. Gas Exchange

Clinical Presentation and Diagnosis

Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor

Pneumocystis pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia can present in a nonspecific manner compared to other types of pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia.

Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor may be subacute and evolve over the course of weeks:

  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways
  • Dry cough Dry Cough Strongyloidiasis
  • Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
  • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome
  • Respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure

Radiographic imaging

  • Chest X-ray may show a variable presentation depending on severity:
    • Normal in 10%–15%
    • Bilateral, patchy opacities
    • Subpleural blebs 
    • Pneumothorax
  • Chest CT generally shows diffuse ground glass opacities and may be compounded by:
    • Alveolar airspace disease
    • Reticular opacities 
    • Septal thickening in presence of ground glass opacities is referred to as “crazy paving.”
    • Mediastinal lymphadenopathy (uncommon)
    • Nodules may form cavities or “tree-in-bud” opacities.
    • Thin-walled cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change (pneumatoceles) may progress to pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax.
  • Extrapulmonary inflammatory changes may also be seen on imaging of the:
    • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy
    • Spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen: Anatomy
    • Kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy

Laboratory evaluation

Definitive diagnosis: 

  • Demonstration of cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change or trophozoites Trophozoites Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the merozoite and then splits into the schizont. Trophozoites that are left over from cell division can go on to form gametocytes. Amebicides in tissue or body fluids:
    • Common modalities:
    • Common stains:
      • Methenamine silver
      • Toluidine Blue O
      • Giemsa 
      • Diff-Quik
      • Monoclonal antibody staining
  • Immunofluorescence assays
  • PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) of induced sputum or BAL fluid

Supporting evaluation:

  • ↑ WBC (note: can be ↓ or normal in HIV infection HIV infection Human immunodeficiency virus (HIV), a single-stranded RNA virus belonging to the Retroviridae family, is the etiologic agent of acquired immunodeficiency syndrome (AIDS). The human immunodeficiency virus is a sexually transmitted or blood-borne infection that attacks CD4+ T lymphocyte cells, macrophages, and dendritic cells, leading to eventual immunodeficiency. HIV Infection and AIDS when baseline WBC is low)
  • LDH LDH Osteosarcoma (reflects tissue damage, but is nonspecific)
  • ↑ β-D-glucan (component of fungal cell wall Cell wall The outermost layer of a cell in most plants; bacteria; fungi; and algae. The cell wall is usually a rigid structure that lies external to the cell membrane, and provides a protective barrier against physical or chemical agents. Cell Types: Eukaryotic versus Prokaryotic, but is nonspecific)
  • Arterial blood gas Arterial blood gas Respiratory Alkalosis
Methenamine silver stain pneumocystis jirovecii

Methenamine silver stain Silver stain The use of silver, usually silver nitrate, as a reagent for producing contrast or coloration in tissue specimens. Legionella/Legionellosis demonstrating Pneumocystis jirovecii cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change within a necrosed granuloma

Image: “Microscopy 800x magnification: Gomori methenamine silver stain Silver stain The use of silver, usually silver nitrate, as a reagent for producing contrast or coloration in tissue specimens. Legionella/Legionellosis” by Patel K. License: CC BY 4.0

Management

General treatment strategies

  • Address any respiratory distress with supplemental oxygen Supplemental Oxygen Respiratory Failure.
  • Antimicrobials 
  • Hemodynamic support in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock physiology 
  • Manage etiology of immunosuppression.

Antimicrobial therapy

  • Trimethoprim-sulfamethoxazole (TMP-SMX) combination is the 1st line:
  • Alternative agents (prior reaction to TMP-SMX or glucose-6-phosphate-dehydrogenase ( G6PD G6PD Pentose Phosphate Pathway) deficiency):
    • Trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim plus dapsone Dapsone A sulfone active against a wide range of bacteria but mainly employed for its actions against Mycobacterium leprae. Its mechanism of action is probably similar to that of the sulfonamides which involves inhibition of folic acid synthesis in susceptible organisms. It is also used with pyrimethamine in the treatment of malaria. Antimycobacterial Drugs 
    • Clindamycin Clindamycin An antibacterial agent that is a semisynthetic analog of lincomycin. Lincosamides plus primaquine Primaquine An aminoquinoline that is given by mouth to produce a radical cure and prevent relapse of vivax and ovale malarias following treatment with a blood schizontocide. It has also been used to prevent transmission of falciparum malaria by those returning to areas where there is a potential for re-introduction of malaria. Adverse effects include anemias and GI disturbances. Antimalarial Drugs 
    • Atovaquone Atovaquone A hydroxynaphthoquinone that has antimicrobial activity and is being used in antimalarial protocols. Antimalarial Drugs
    • Pentamidine

Prophylaxis Prophylaxis Cephalosporins

Prophylaxis Prophylaxis Cephalosporins varies depending on the etiology of the immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis state:

  • HIV HIV Anti-HIV Drugs patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with CD4 count < 200 cells/μL or presence of oropharyngeal candidiasis Oropharyngeal candidiasis Infection of the mucous membranes of the mouth by a fungus of the genus candida. Candida/Candidiasis
    • TMP-SMX is the 1st line agent.
    • Dapsone Dapsone A sulfone active against a wide range of bacteria but mainly employed for its actions against Mycobacterium leprae. Its mechanism of action is probably similar to that of the sulfonamides which involves inhibition of folic acid synthesis in susceptible organisms. It is also used with pyrimethamine in the treatment of malaria. Antimycobacterial Drugs is an alternative.
    • Stop prophylaxis Prophylaxis Cephalosporins therapy once CD4 count > 200 cells/μL.
  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship on chronic steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors: Continue TMP-SMX until steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors are < 20 mg daily.
  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship receiving chemotherapy Chemotherapy Osteosarcoma or immunosuppressive agents temporarily: TMP-SMX until treatment is complete and the immune system Immune system The body’s defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs has recovered.
  • Transplant recipients: 
    • TMP-SMX should be given as long as high-dose immunosuppressive therapy is required.
    • Lifelong therapy is typically required in lung transplant patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship.

Complications and Prognosis

Complications

Complications of PCP include:

  • ARDS ARDS Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Acute Respiratory Distress Syndrome (ARDS): Address with invasive or noninvasive ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing, and high-flow oxygenation (depending on severity).
  • Pneumatoceles:
    • May contribute to pneumomediastinum Pneumomediastinum Mediastinitis and pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax
    • If possible, avoid high levels of positive pressure ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing.
  • Pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax: may require chest tube placement Chest tube placement Surgical procedure involving the creation of an opening (stoma) into the chest cavity for drainage; used in the treatment of pleural effusion; pneumothorax; hemothorax; and empyema. Pleural Effusion or needle decompression Needle Decompression Pneumothorax (if tension physiology is present)
  • Secondary infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease:
    • May be bacterial, fungal, or viral
    • Supported by additional culture data
    • Treat with appropriate antimicrobials.

Prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

Early recognition and initiation of therapy improves prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas.

Factors negatively impacting outcomes:

  • Old age
  • HIV HIV Anti-HIV Drugs
  • Coexisting viral pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia
  • ICU ICU Hospital units providing continuous surveillance and care to acutely ill patients. West Nile Virus requirement

Differential Diagnosis

  • Other infectious Infectious Febrile Infant pneumonias: can be viral, bacterial, or fungal. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship may present with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, shortness of breath Shortness of breath Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, cough, and malaise Malaise Tick-borne Encephalitis Virus. A thorough history should address risk factors for COVID-19 COVID-19 Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that mainly affects the respiratory system but can also cause damage to other body systems (cardiovascular, gastrointestinal, renal, and central nervous systems). , influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza, tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis, and Mycoplasma Mycoplasma Mycoplasma is a species of pleomorphic bacteria that lack a cell wall, which makes them difficult to target with conventional antibiotics and causes them to not gram stain well. Mycoplasma bacteria commonly target the respiratory and urogenital epithelium. Mycoplasma pneumoniae (M. pneumoniae), the causative agent of atypical or “walking” pneumonia. Mycoplasma pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia. Diagnosis is based on history, exam, imaging, cultures Cultures Klebsiella, and viral testing. Treatment includes supportive care, supplemental oxygenation, and antimicrobials.
  • Pulmonary alveolar proteinosis: a rare disease characterized by abnormal intra-alveolar accumulation of surfactant-derived, lipoproteinaceous material. Pulmonary alveolar proteinosis is classically associated with a pattern of crazy paving on CT scan. Diagnosis is based on BAL staining, and supported by granulocyte macrophage colony-stimulating factor Granulocyte macrophage colony-stimulating factor An acidic glycoprotein of mw 23 kda with internal disulfide bonds. The protein is produced in response to a number of inflammatory mediators by mesenchymal cells present in the hemopoietic environment and at peripheral sites of inflammation. GM-CSF is able to stimulate the production of neutrophilic granulocytes, macrophages, and mixed granulocyte-macrophage colonies from bone marrow cells and can stimulate the formation of eosinophil colonies from fetal liver progenitor cells. GM-CSF can also stimulate some functional activities in mature granulocytes and macrophages. White Myeloid Cells: Histology ( GM-CSF GM-CSF An acidic glycoprotein of mw 23 kda with internal disulfide bonds. The protein is produced in response to a number of inflammatory mediators by mesenchymal cells present in the hemopoietic environment and at peripheral sites of inflammation. GM-CSF is able to stimulate the production of neutrophilic granulocytes, macrophages, and mixed granulocyte-macrophage colonies from bone marrow cells and can stimulate the formation of eosinophil colonies from fetal liver progenitor cells. GM-CSF can also stimulate some functional activities in mature granulocytes and macrophages. White Myeloid Cells: Histology) antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions and clinical history. Treatment may involve whole-lung BAL and GM-CSF GM-CSF An acidic glycoprotein of mw 23 kda with internal disulfide bonds. The protein is produced in response to a number of inflammatory mediators by mesenchymal cells present in the hemopoietic environment and at peripheral sites of inflammation. GM-CSF is able to stimulate the production of neutrophilic granulocytes, macrophages, and mixed granulocyte-macrophage colonies from bone marrow cells and can stimulate the formation of eosinophil colonies from fetal liver progenitor cells. GM-CSF can also stimulate some functional activities in mature granulocytes and macrophages. White Myeloid Cells: Histology supplementation. 
  • Pneumonitis Pneumonitis Human Herpesvirus 6 and 7: inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the lung tissue commonly related to a variety of exposures, including medication, aspiration, environmental, and/or radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship can present with an acute or chronic process with symptoms resembling an infectious Infectious Febrile Infant process. Diagnosis is clinical and radiological. Infection should be ruled out. Treatment includes eliminating the offending agent, addressing the underlying cause, and corticosteroids Corticosteroids Chorioretinitis or other immunosuppressive agents. 
  • Pulmonary hemorrhage: commonly related to an inflammatory process, which may include vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus, connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology disease, infection, medication, and coagulopathy. Pulmonary hemorrhage may present as a cough (with or without hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis), fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, chills Chills The sudden sensation of being cold. It may be accompanied by shivering. Fever, and/or shortness of breath Shortness of breath Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea. Diagnosis is made with clinical history, imaging, and alveolar fluid analysis. Treatment includes supportive care, respiratory support with supplemental oxygenation, and addressing the underlying cause. 
  • Cryptogenic organizing pneumonia Cryptogenic organizing pneumonia An interstitial lung disease of unknown etiology, occurring between 21-80 years of age. It is characterized by a dramatic onset of a ‘pneumonia-like’ illness with cough, fever, malaise, fatigue, and weight loss. Pathological features include prominent interstitial inflammation without collagen fibrosis, diffuse fibroblastic foci, and no microscopic honeycomb change. There is excessive proliferation of granulation tissue within small airways and alveolar ducts. Bronchiolitis Obliterans: an inflammatory and scarring Scarring Inflammation form of idiopathic Idiopathic Dermatomyositis, interstitial pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia, which leads to obstruction of the small airways and alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS). Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship may present with flu-like symptoms Flu-Like Symptoms Babesia/Babesiosis. Diagnosis is made radiologically after infection has been ruled out. Cryptogenic organizing pneumonia Cryptogenic organizing pneumonia An interstitial lung disease of unknown etiology, occurring between 21-80 years of age. It is characterized by a dramatic onset of a ‘pneumonia-like’ illness with cough, fever, malaise, fatigue, and weight loss. Pathological features include prominent interstitial inflammation without collagen fibrosis, diffuse fibroblastic foci, and no microscopic honeycomb change. There is excessive proliferation of granulation tissue within small airways and alveolar ducts. Bronchiolitis Obliterans is considered idiopathic Idiopathic Dermatomyositis in etiology, and treatment generally consists of steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors.

References:

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