Lung Path 4 Pulmonary Infections and Lung Transplants (Singh) Flashcards
(144 cards)
1
Q
What are the 4 stages of the inflammatory response which have been classically described for lobar pneumonia?
A
1) Congestion: vascular engorgement; intra-alveolar fluid
2) Red hepatization: massive exudation of alveolar spaces w/ lots of neutrophils; red, firm, airless lobe; liver-like consistency
3) Gray hepatization: disintegration of red cells w/ fibrinosuppurative exudate
4) Resolution: fibrosis and macrophage clean-up
2
Q
Congested septal capillaries due to massive confluent exudation w/ numerous intra-alveolar neutrophils is characteristic of what stage of lobar pneumonia?
A
Red Hepatization
3
Q
Which inflammatory stage of lobar pneumonia is characterized by progressive disintegration of red cells and the persistence of a fibrinosuppurative exudate?
A
Grey Hepatization
4
Q
Exudates within alveolar spaces converted into fibromyxoid masses rich in macrophages is characteristic of which inflammatory stage of lobar pneumonia?
A
Resolution/Organization
5
Q
What are the gross morpholigical features of hepatization?
A
Noarmal vs.
Red
Gray
etc..
6
Q
What is the most common cause of death in viral influenza epidemics?
A
Superimposed bacterial pneumonia
7
Q
What are 2 acute phase markers made in the liver that are specific for bacterial infection and can be useful in pneumonia diagnosis?
A
- CRP
- Procalcitonin
8
Q
What organisms cuase communiy acquired pneumonia (CAN)?
A
S. pneumoniae
H. influenzae
S. aureus
K. pneumoniae
P. aeruginosa
L. pneumophila
M. pneumoniae
9
Q
Which serotype of the encapsulated H. influenzae is most virulent?
A
Type B
10
Q
What will the sputum culture of a patient with community-acquired bacterial pneumonia caused by Streptococcus pneumoniae show morphologically?
A
Lancet-shaped gram (+) diplococci in pairs and chains
11
Q
Which patient population is at a high risk for development of invasive infection by H. influenzae?
A
Neonates and children w/ comorbidities
12
Q
What is the 1st and 2nd most common bacterial cause of acute exacerbation of COPD?
A
- Most common = H. influenzae
- 2nd = M. catarrhalis
13
Q
Pneumonia caused by what bacteria is a pediatric emergency due risk of acute epiglottitis w/ high mortality rate?
A
H. influenzae
14
Q
What is the pulmonary consolidation associated w/ H. influenzae typically like?
A
Lobular and Patchy
15
Q
Which patient population is especially susceptible to bacterial pneumonia by Moraxella Catarrhalis?
A
Elderly
16
Q
S. aureus pneumonia is associated with a high incidence of which 2 complications?
A
- Lung abscess
- Empyema (aka pus in the pleural space)
17
Q
What is the most frequent cause of gram-negative bacterial pneumonia and who does it most commonly afflict?
A
- Klebsiella pneumoniae
- Debilitated and malnourished people, particularly chronic alcoholics
18
Q
What type of sputum is characteristic of Klebsiella pneumoniae?
A
Thick, mucoid (blood-tinged) –> “currant jelly”
19
Q
Pseudomonas aeruginosa is a common cause of pneumonia in whom and in what setting?
A
Hospital acquired
Cystic Fibrosis
Immunocompromised
(fun fact: aeruginosa means copper rust)
20
Q
What is the gram stain, shape, and O2 dependency of Pseudomonas aeruginosa?
A
AEROBIC Gram NEGATIVE; bacillus
21
Q
What are the characteristics of typical pneumonia?
A
- More abrupt onset
- Respiratory symptoms predominate
- Consolidation on CXR
- Older adults or young children
22
Q
What are the characteristics of atypical (walking) pneumonia?
A
- Slower onset
- Systemic symptoms predominate
- Patchy infiltrates on CXR
- Young adults/teens/older children
23
Q
Mycoplasma pneumoniae infections are common in which age groups and occur most often how?
A
Children and young adults (<30)
Sporadically or as local epidemics (i.e., schools, military camps, prisons)
Smallest free-living, self- replicating microorganisms
NO CELL WALL!
24
Q
Which cause of bacterial pneumonia is classically seen in military recruits or college student i.e., those living in close quarters?
A
Mycoplasma pneumonia
25
Which bacteria cause of pneumonia flourished in warm freshwater (i.e., AC units, misters, hot tubs); what does it live inside?
*Legionella pneumophila*
Lives in amoebas
26
What are the 2 common modes of transmission for *Legionella pneumophilia?*
- **Inhalation** of **aerosolized** organisms
- **Aspiration** of **contaminated** drinking water
27
What is the gram stain and morphology of *Legionella pneumophila?*
**Gram NEGATIVE** **bacillus**
28
Pt's with what predisposing conditions are most at risk for ***Legionella*** pneumonia?
Pt's w/ **cardiac**, **renal**, **immunologic**, or **hematologic** diseases
## Footnote
**Organ transplant recipients\*\*\*\***
**Elderly smokers**
29
How is rapid diagnosis of *Legionella pneumophila* done and what is the gold standard?
- *Legionella* **Ags** in the **urine**
- **(+) fluorescent Ab** test on **sputum samples**
- **CULTURE** = **gold standard**
30
Which bacterial cause of pneumonia is associated with **hypokalemia**, **elevated CPK**, and **lobar infiltrates?**
*Legionella pneumophila*
31
Air-fluid level within cystic space seen on CXR associated with pneumonia suggests what?
Common causes?
Lung **abscess**
Compliction from S. aureus or K. phenumoniae
Apiration (EtOH, elderly, or anearobic bacteria) --\> tends to follow gravity
32
What is a common cause of postobstructive pneumonia which may lead to abscess formation?
**Neoplasia** causing **obstruction**
33
What is a cause of lung abscess which may originate in systemic venous circulation or the right side of the heart?
**Septic embolism**
34
When all the causes have been exluded and in which there is no discernible basis for lung abscess formation, what is this referred to as?
**Primary cryptogenic lung abscesses**
35
Lung abscesses due to aspiration are more common on which side of the lung and are most often (single/mutliple)?
**Right** side of lung; most often **single**
36
What is the cardinal histologic change in all lung abscesses?
**Suppurative** destruction of the **lung parenchyma** within the **central area** of **cavitation**
37
Clinical signs/sx's of lung abscess?
- **Cough** + fever + **copious** amounts of **foul-smelling** **purulent** or **bloody** sputum
- Fever + chest pain + **weight loss** = common
- **Clubbing** of digits may appear within a few weeks
38
If a lung abscess is discovered in an elderly pt, what must be ruled out?
Underlying **carcinoma**
39
Complications which may arise from a lung abscess?
- Extension into **pleural cavity**
- **Hemorrhage**
- **Brain abscesses** or **meningitis** from **_septic emboli_**
- Rarely, **secondary amyloidosis (AA)**
40
**Tissue destruction** and **abscess** formation as a complication of pneumonia are most common associated w/ what 3 organisms?
**- Type 3 pneumococci**
***- Klebsiella***
***- S. aureus***
41
Patchy consolidation of the lung is the dominant characteristic of what type of bacterial pneumonia?
Bronchopneumonia
42
Which pattern of bacterial pneumonia is often **multilobular** and frequently **bilateral** and **basal**?
Bronchopneumonia
43
Histologically, the rxn associated with bronchopneumonia shows areas of acute suppurative inflammation rich in what type of immune cell?
**Neutrophilic** exudate filling bronchi, bronchioles, and adjacent alveolar spaces
44
Bacteremic dissemination as a complication of pneumonia can spread where and cause what?
- Heart valves, pericardium, brain, kidneys, spleen, or joints
- **Metastatic abscesses**, endocarditis, **meningitis**, or suppurative arthritis
45
What are the major sx's of acute bacterial pneumonia?
- Abrupt onset of **high fever** + **shaking chills** + **cough**
- **Mucopurulent sputum** and occasionally hemoptysis
46
What are the 2 most important components in term of virulence for Influenza virus allowing it to cause infections; function of each?
- **Hemagglutinin**: allows for **attachment** to cells; via **sialic acid** residues
- **Neuraminidase**: allows **release of** replicated virus from cells; cleaves **sialic acid** residues
47
What is **antigenic drift** in regards to Influenza virus and what changes occur; leads to **what type of outbreak**?
**Spontaneous** mutation that alter antigenic epitopes on the vial **Hemagglutinin** and **Neuraminidase** proteins
--\> Result in new viral strains, leading to **epidemics**
48
What is **antigenic** **shift** in regards to Influenza virus and what changes occur; leads to **what type of outbreak**?
Both **hemagglutinin** and **neuraminidase** genes are replaced through **recombination** w/ **animal influenza viruses (maybe ?).**
Resulting in major changes in protein structure
--\> Leads to **pandemics**
49
If influenza virus gains entry into pneumocytes what are the cytopathic changes that it can elicit which contribute to its pathogenesis?
- **Inhibits Na+** channels --\> electrolyte + H2O shifts = **fluid accumulation** in **alveolar lumen**
- **Inhibits** host cells mRNA translation and **activates** caspases --\> **cell death** via **apoptosis**
50
What complications may arise with viral pneumonia as a result of activation of the nearby pulmonary endothelium causing lung injury?
For all viruses
**ARDS**
**Fatal pulmonary disease** from **superimposed bacterial infection**
In case of COVID
**cytokine storm**
51
Which bacteria is most commonly found as cause of superimposed bacterial infection on a viral pneumonia?
*Staphylococcus aureus*
52
Which family of viruses does SARS belong to?
Coronavirus
53
Why is SARS a distinct coronavirus in terms of infection?
- Many upper respiratory infections are caused by coronavirus
- SARS differs in that it can infect the **lower respiratory** tract and **spread** throughout the body
54
What is the molecular pathogenesis of COVID?
Explain image...
**Take note of the D-dimer!**
--\> It correlates with a poorer outcome in COVID patients due to the thrombotic complications
55
What histological findings might you see in a biopsy for a COVID pt?
diffuse alveolar damage as well as a fibrin microthrombus
56
What uniqe cells in circulation can help you identify COVID?
Megakaryocytes
57
Besides, the lung and circulation, where else may you find megakaryocytes associated with COVID?
liver
heart
kideny
She said IMPORTANT slide!
58
Which family of viruses does Human Metapneumovirus (MPV) belong to?
Paramyxovirus
59
What is the only antiviral tx that is currently available for human MPV infections and is most commonly used for immunocompromised pt's w/ severe disease?
Ribavirin
60
Respiratory syncytial virus (RSV) belongs to what family of viruses?
Paramyxovirus
61
How does respiratory syncytial virus (RSV) spread from the nasopharynx to lower respiratory tract; what is the effect of viral replication on this process?
- **Attaches to** and **infects** host **epithelial** cells in nasopharynx
- Cells are **sloughed** and **aspirated**, carrying RSV to lower respiratory tract cells
- **Viral replication** leads to **abnormal sloughing** of epithelial cells, **inflammatory cell infiltration**, ↑ **mucus secretion** and **impaired ciliary action**
62
Which virus is associated w/ sx's of rhinorrhea, cough, wheezing, dyspnea, tachypnea, and cyanosis in an infant?
RSV
63
What are 5 major viral causes of pneumonia in children \>1 month?
RSV\*\*
Parainfluenza virus
Influenza A and B,
Adenovirus,
Rhinovirus
64
What viruses belong the the paramyxoviridea fam affecting mostly children?
**RSV:** Respiratory syncytial virus
**hMPV:** human Metapneumovirus (pages 706-7, Robbins)
Parainfluenza
Measles! (if not vaccinated)
65
How does the inflammatory rxn (location and immune cells) differ between bacterial vs. viral causes of pneumonia?
BACTERIAL
**inside alveoral spacee with** **_neutrophilic_** inflammation "linear progression"
VIRAL
**interstitial** **_lymphocytic_** inflammatory rxn**; walls** of alveoli; "goes everywhere"
66
When viral pneumonia is complicated by ARDS what is seen lining the alveolar walls?
Pink **hyaline** membranes
67
What are the 3 major bacterial causes of pneumonia in neonates?
- Group B strep
- Gram negative bacilli
- Listeria
68
What are 4 major bacterial causes of pneumonia in children \>1 month?
- *S. pneumoniae*
- *M. catarrhalis*
- *H. influenzae*
- *S. aureus*
69
Viral-induced tonsillitis causing hyperplasia of the lymphoid tissue within what is common in children?
Waldeyer ring
70
What are the 3 major morphological changes seen in upper respiratory viral infections?
- Mucosal **hyperemia**
- Lymphomonocytic and plasmacytic **infiltration** of **submucosa**
- **Overproduction** of **mucus** secretions
71
Which 3 viruses may be associated with necrosis of bronchial and alveolar epithelium and acute inflammation?
- Herpes simplex
- Varicella
- Adenovirus
72
What is the onset, fever, and infiltration seen on CXR like for bacterial vs. viral causes of pneumonia?
- **Bacterial** has **abrupt onset** w/ **high fever**; and **lobar/consolidated** appearance
- **Viral** has **gradual onset** w/ **absent** or **low-grade fever**; and **diffuse infiltrates** on CXR
73
Bacterial causes of pneumonia are not typically associated w/ epidemics, except those caused by what 2 types?
- **Legionella**
- **Pertussis**
74
A red, flat to slightly bumpy (maculopapular) rash that starts on the forehead and spreads to the face, neck, torso, and finally the feet is associated with what virus?
**Measles** (paramyxovirus)
75
What is the gram stain and shape of *Bordatella pertussis?*
**Gram negative** **bacillus**
76
What are the 4 major virulence factors of *Bordetella pertussis?*
- **Pertussis toxin**: activates G proteins --\> ↑cAMP
- **Extracytoplasmic adenylate cyclase**: "weakens" immune cells
- **Filamentous hemagglutinin**: binding to ciliated epithelial cells
- **Tracheal cytotoxin**: kills ciliated epithelial cells
77
While working the pediatric ED, you see a child with a sore throat and fever. There is a dark exudate on the child's pharynx, which appears darker and thicker than that of strep throat; which bacteria is most likely responsible and what its gram stain/shape?
* -* ***Corynebacterium diptheriae***
- Gram **positive** rods - very pleomorphic and **club**-shaped
78
If *Corynebacterium diptheriae* is suspected why must you NOT scrape the pseudomembranes formed on the pharynx; may lead to what?
- May **bleed** and **systemic absorption** of **lethal EXOTOXIN** will be enhanced
- Can cause: **myocarditis** and **neural involvement** (peripheral nerve palsies, Guillan Barre-like syndrome, and palatal paralysis/cranial neuropathies
79
What is the gram stain and shape of *Listeria monocytogenes?*
**Gram POSITIVE rod**
80
What are the 2 most common organisms isolated in association with Health Care-Associated Pneumonia?
- ***P. aeruginosa***
- **MRSA**
81
How is health care-associated pneumonia different from hospital-acquired pneumonia?
- **Health care** = recent hospitalization, presenting from nursing/long-term care facility; attending hospital or hemodialysis clinic; recent IV abx, chemotherapy, or wound care
- **Hospital-acquired** = acquired while in the hospital
82
Patients on what are at particularly high-risk of hospital-acquired pneumonia?
Mechanical ventilation
83
What are the most common gram positive and gram negative organisms responsible for hospital-acquired pneumonia?
- **Gram (+) cocci** --\> ***S. aureus*** and ***S. pneumonia***
- **Gram (-) rods** --\> **Enterobacteriaceae** (i.e., *Klebsiella spp., Serratia,* and *E. coli)* and ***Pseudomonas*** species
84
Which bacteria is a common cause of bacteria in pt's with CF, burn victims, and those with neutropenia?
***P. aerugionosa*** (Gram negative rod)
85
Which bacterial cause of pneumonia is especially common in organ transplant recipients?
*Legionella pneumophila*
86
What are the 4 anaerobic oral bacteria commonly recovered in the culture of pt with **aspiration** pneumonia?
- Bacteroides
- Prevotella
- Fusobacterium
- Peptostreptococcus
87
What are 3 **atypical** (aka not detectable on gram stain or with culture) bacteria associated with pneumonia?
- *Mycoplasma pneumoniae*
- *Chlamydophila pneumoniae*
- *Coxiella burnetii*
88
Aspiration pneumonia occurs most frequently in whom; what are the risk factors?
**- Markedly debilitated** pt's + pt's who aspirate gastric contents while **unconcious** or during **repeated vomiting**
- **Acute/chronic alcoholism**, COMA, **stroke**, anesthesia, sinusitis, **gingivodental sepsis**
89
What type of damage is seen with aspiration pneumonia and what is its typical course?
Abscess formation, which is often **necrotizing** and pursues **fulminant** clinical course --\> **Frequent** cause of **death**
**Food particle** in inflammatory exudate indicating aspiration
90
In those who survive aspiration pneumonia what is a frequent complication that arises?
Lung abscesses
91
Microaspiration is commonly seen in pt's with what condition?
What type of immune rxn/damage does it result in?
- Pts w/ **GERD**
- Results in **small,** poorly formed **NON-caseating granulomas** w/ **multinucleated** foreign body **giant cell rxn**
92
Which chronic lung disease puts people at a particularly high risk for tuberculosis?
Silicosis
93
Which **critical** mediator released from TH1 cells both in LN's and the lung enables macrophages to contain *M. tuberculosis* infection?
IFN-γ
94
Which immune cells orchestrate the formation of granulomas and caseous necrosis seen in *M. tuberculosis* infection?
TH1
95
Macrophages activated by IFN-γ in *M. tuberculosis* infection differentiate into what?
"**Epithelioid histiocytes"** that aggregate to form **granulomas**; some may aggregate to form **giant cells**
96
Pt's with RA treated with what type of drugs are at an increased risk for tuberculosis reactivation?
**TNF** antagonist
97
Which pattern of tuberculosis arises in a nonimmune host vs. previously sensitized host?
- **Non-immune** = primary TB
- **Previously sensitized** = secondary TB
98
Secondary pulmonary tuberculosis classically involves which area of the lungs?
**APEX** of **one** or **both** lungs
99
What are the systemic and pulmonary signs/sx's associated with secondary tuberculosis?
- **Remittent/low-grade** **FEVER** + **WEIGHT LOSS** + **Night sweats**
- Fever appears late each afternoon and then subsides
- **Sputum** that at first is **mucoid** and later **purulent**; variable degree of **hemoptysis**
100
Which laboratory diagnostic test allows for more rapid diagnosis of *M. tuberculosis?*
**PCR** amplification of *M. tuberculosis* **DNA**
101
What remains the gold standard for confirming diagnosis of *M. tuberculosis?*
Culture
102
What is a risk factor in HIV infected pt's before starting HAART which increases risk for developing tuberculosis?
Low CD4 count
103
Primary tuberculosis almost always begins in which organ and what is seen morphologically as sensitization develops?
- **Lungs** --\> bacilli implant in the distal airspaces of **lower** part of **upper lobe** or **upper** part of **lower lobe**
- **Gray-white** inflammation **w/ consolidation**, know as **Ghon focus** --\> center of focus undergoes **caseous necrosis**
104
Ghon complex seen in primary TB is a combination of what?
**Parenchymal lung lesion (Ghon focus****)**+**LN involvement**
105
Cell-mediated immunity typically controls the primary TB infection leading to what morphological change in the Ghon complex, which is often followed by what radiologically detectable change?
Ghon complex undergoes **progressive fibrosis**, followed by **radiologically** detectable **calcification** (**Ranke complex**)
106
What type of pneumonia is most often a localized lesion in the immunocompetent pt, with or without LN involvement; typically featuring a granulomatous inflammatory rxn?
Chronic pneumonia
107
Which subset of pt's **do NOT** form the characteristic granulomas associated with primary TB and instead have macrophages loaded with many bacilli?
**Immunocompromised**
108
With progressive pulmonary tuberculosis, the pleural cavity is almost invariably involved, and what 3 complications may be seen here?
- **Pleural effusions**
- **Tuberculous empyema**
- **Obliterative fibrous pleuritis**
109
Systemic miliary tuberculosis is most prominent in which organs/structures?
- Liver
- Bone marrow (**osteomyelitis**)
- Spleen
- Adrenals (**Addison diseas**)
- Meninges (**tuberculous meningitis**)
- Kidneys (**renal tuberculosis**)
- Fallopian tubes (**salpingitis**) and Epididymis
110
When the vertebrae are affected by isolated tuberculosis this is known as what?
Parapsinal "cold" abscesses in these pt's may track along tissue planes and present how clinically?
- **Pott disease**
- Present as **abdominal** or **pelvic mass**
111
What is the most frequent presentation of extra-pulmonary tuberculosis (aka what is most often affected)?
Lymphadenitis
112
How does lymphadenitis and the presentation differ in HIV-negative vs. HIV-positive pt's with active tuberculosis?
- **HIV-negative** = lymphadenitis tends to be **unifocal** and **localized**
- **HIV-positive** = tends to be **multifocal** disease w/ **systemic sx's**, and either **pulmonary** or other organ involvement
113
*Histoplasma capsulatum* infection is acquired via inhalation of what?
Dust particles from soil **contaminated** with **bird** or **bat droppings** containing **small spores (microconidia)**
114
*Histoplasma capsulatum* is endemic where; where else is it seen?
- **Endemic** --\> **Ohio** and **Mississippi rivers** and **Caribbean**
- Also found in Mexico, Central and S.A., parts of Europe, Africa, east Asia, and Australia
115
*Histoplasma capsulatum* typically causes what type of infection with what type of immune response; what is seen on CXR?
- **Subclinical** infection with **granulomas**, which usually undergo **caseation** necrosis and coalesce to produce large areas of **consolidation**
- **Calcifications** ("**tree-bark appearance**) or **coin lesions** on CXR
116
What is the morphology (aka shape) of the yeast forms seen with *Histoplasma capsulatum?*
**Thin-walled** yeast w/ **"pumpkin seed"** morphology
117
How is the diagnosis of *Histoplasma capsulatum* established; when are serological tests for Abs and Ags most useful?
- Via **culture** or identification of **fungus** in **tissue lesions**
- Ag detection **most useful** in the **early stages**
118
Granulomas in the lungs associated with *Histoplasma capsulatum* may **liquefy** and form cavities in pt's with what underlying disease?
COPD
119
What are the 4 clinical presentations/morphological lesions which may be associated with *Histoplasma capsulatum?*
1. **Self-limited** and often **latent** primary pulmoanry involvement; **coin-lesions** on CXR
2. **Chronic, progressive** lung disease, localized to **apices** and causes **cough, fever**, and **night sweats**
3. **Extrapulmonary spread** --\> **mediastinum, adrenals, liver**, or **meninges**
4. **Widely disseminated** disease in **immunocompromised**
120
How is the morphology of the disease caused by *Histoplasma capsulatum* different in immunosuppressed individuals?
- Causes **fulminant disseminated histoplasmosis**
- **Granulomas** do **NOT** form
- Instead there are **focal** accumulations of **mononuclear phagocytes** FILLED w/ **fungal yeasts** throughout the body
121
*Blastomyces dermatitidis* is a soil-inhabiting **dimorphic** fungi that is endemic where in the US and also seen in what other countries?
- **Central** (Ohio and Mississippi river valleys) and **SE** United States
- Also seen in **Canada, Mexico**, the **Middle East, Africa**, and **India**
122
How does **pulmonary** *Blastomyces dermatitidis* infection typically present clinically (signs/sx's)?
- **ABRUPT** onset w/ **productive cough** + **HA** + **chest pain**
- **Weight loss** + **fever** + **night sweats** + **chills**
123
How do the lung lesions of *Blastomyces dermatitidis* appear morphologically in a normal host?
Which immune cells are seen in high numbers?
- **Suppurative granulomas**
- Macrophages have **limited** ability to ingest and kill this organism; persistence of this yeast leads to ↑↑ **neutrophils**
124
What is the characteristic morphology of *Blastomyces dermatitidis* that distinguishes it from other fungi?
- **Round** w/ **BROAD-BASED BUDDING**
- **THICK**, double-contoured **cell-wall**
125
Involvement of the skin and larynx by *Blastomyces Dermatitidis* caused what change to epithelial cells and may be mistaken for what?
- **Marked** **epithelial hyperplasia**
- May be **mistaken** for **SCC**
126
Where is *Coccidioides immitis* endemic and in the lungs what does the infection cause?
- **Endemic** in **SW United States** and **Mexico**
- Causes **granulomatous** response w/ **eosinophils**
127
What are the signs/sx's of pulmonary and cutaneous infection with *Coccidioides immitis?*
- **Fever + cough + pleuritic chest pain**
- **Erythema nodosum** or **erythema multiforme** (the **San Joaquin Valley fever complex**)
128
Which pt population and ethnic groups are at the highest risk for the rare disseminated infection caused by *Coccidioides immitis?*
What type of lesions dominate in the disseminated disease?
- **Filipino** and **African Americans**
- **Immunosuppressed**
- **Purulent** lesions dominate
129
What is the characterisitc morphology of *Coccidioides immitis* that distinguishes it from other fungi?
- **THICK-walled**, **NON**-budding **SPHERULES**
- Often **filled** w/ **small endospores**
130
A pt with known lung disease presents with **recurrent hemoptysis**, a tissue sample from the lungs shows this; what is the diagnosis and how do you know?
- **Aspergillosis**
- **Septate hyphae** w/ **acute-angle branching** (**40 degrees**)
131
A tissue biopsy of a pt with granulomatous lung disease shows this; what oganism is this most consistent with?
*Coccidioides immitis*
132
Which is the **_most common_** opportunistic fungal infection in the immunocompromised that also an AIDS-defining illness?
Pneumocystis jiroveci (carinii)
Can cuase diffuse, focal, or any other pattern on radiographs
133
What pt populations are most frequency affected by Mycobacterium avium complex (MAC)?
Elderly and immunocompromised
Histologically, thin mycobacteria seen as slender red forms on acid-fast staining
134
List 3 common causes of **diffuse** pulmonary infiltrates in an immunocompromised host?
- CMV
- ***Pneumocystis jiroveci***
- Drug rxn
135
List 5 common causes of **focal** pulmonary infiltrates in immunocompromised hosts
- **Gram-negative** bacterial infections
- ***S. aureus***
- ***Aspergillus***
- ***Candida***
- **Malignancy**
136
What is the hallmark finding of MAC infections in patients with immunosuppressed (i.e., HIV, elderly, transplant); morphology of the organism?
- Abundant **ACID-FAST** **bacilli** within **macrophages**
- **Thin** mycobacteria seen as **slender red forms**
137
Common sx's of pt with HIV who become infected with MAC?
**Fever** + **drenching night sweats** + **weight loss**
141
Opportunistic infections are common causes of pneumonia in HIV pt's, but what are 4 of the more common "usual" bacteria that may be seen?
- *S. pneumoniae*
- *S. aureus*
* -* *H. influenzae*
- Gram-negative rods
142
As a general rule of thumb which organisms causing infection in HIV pt's are more likely with a **CD4** count **\>200, \<200, and \<50**?
- **\>200** = bacterial and tubercular infections
- **\<200** = ***Pneumocystis*** pneumonia
- **\<50** = CMV, fungal, and ***Mycobacterium avium*** **complex**
143
What is the morphology of acute rejection of a lung transplant that differentiates it from an infection?
**Rejection** shows **mononuclear** infiltates around **small vessels**, in **submucosa** of airways, or **both**
144
What is the major morphological pattern of damage seen with **chronic** rejection following a lung transplant?
**Bronchiolitis obliterans** --\> **fibrosis** causing partial or complete occlusion of small airways WITH or WITHOUT active inflammation
145
What is most likely seen on CXR of pt with HIV infected with *Pneumocystis jiroveci?*
- **Diffuse** BILATERAL **interstitial** infiltrates
- Can also be **focal** or show **nothing**!
147
Which type of organism is the most common cause of pulmonary infection in the early post-transplant period (first few weeks)?
Bacterial
148
Since **acute rejection** following a lung transplant has a **similar** picture to **infections**, diagnosis relies on what?
Transbronchial biopsy
