Bacterial Infections Part 2 Flashcards
1
Q
Pseudomonas Infection
A
- P.aeruginosa, opportunistic aerobic Gram-negative bacillus.
- Seen in those with CF, burns, neutropenia, and is often a hospital-acquired infection.
- Causes corneal keratitis in contact lens wearers and external otitis (swimmer’s ear).
2
Q
Pseudomonas Infection Virulence Factors
A
- Pili and adherence proteins that bind to epithelial cells and lung mucin.
- Endotoxin that cause gram-neg sepsis.
- Exotoxin A that inhibits protein synthesis like Diptheria.
- Phospholipase C that lyses red cells and degrades surfactant and an elastase that degrades IgG and ECM.
- In those with CF, secretes an exopolysaccharide (alginate) that forms a slimy biofilm that protects bacteria.
3
Q
Pseudomonas Findings
A
- Skin infections give rise to well-demarcated necrotic and hemorrhagic skin lesions, exthyma gangrenous.
4
Q
Plague
A
- Yersinia, gram-neg facultative intracellular bacterium.
- Pestis causes plague, transmitted from rodents to humans by aerosols or fleas.
- Enteocolitica and pseudo tuberculosis cause fecal-oral transmitted ileitis and mesenteric lymphadenitis.
5
Q
Yersinia Virulence
A
- Toxins called Yops are injected into host by a syringe-like mechanism, they block phagocytosis and cytokine production.
- A biofild obstructs the flea GI tract, causing it to throw up prior to feeding and thus infection ensues.
6
Q
Yersinia Findings
A
- Massive lymph node involvement (buboes), pneumonia, and sepsis, with extensive bacterial proliferation, tissue necrosis, and neutrophilic infiltrates.
7
Q
Granuloma Inguinale
A
- STI caused by Klebsiella (encapsulated coccobacillus)
- Begins as a papule on genitalia or elsewhere that ulcerates and granulates to form a soft, painless mass with prominent epithelial hyperplasia at borders.
- Lesion may scar and cause strictures.
8
Q
Tuberculosis
A
- Second leading cause of death worldwide (after HIV)
- Transmitted via aerosol.
- Virulence is based on the properties of its waxy cell wall made of mycolic acid.
9
Q
Tuberculosis Findings
A
- TH1 mediated delayed hypersensitivity response that activates macrophages via interferon gamma to promote endocytosis and killing via NO, promote cidal activity through TNF production, surround microbes with granulomatous inflammation.
- Caseating granulomas are characteristic, central necrosis surrounded by lymphocytes and activated macrophages.
10
Q
Tuberculosis Caseating Granulomas
A
Formed in response to infection typically involved the lung apex and draining lymph node; these are called a Ghon complex.
11
Q
Leprosy
A
- Also called Hansen’s Disease.
- Waxy cell wall made of mycolic acid: M. Leprae.
- Inhaled M, Leprae are phagocytized by pulmonary macrophages and spread hematogenously.
- Secretes no toxins, virulence from cell wall.
12
Q
Tuberculoid Leprosy
A
- TH1 response (IFN-gamma)
- Granulomatous inflammation-few bacilli.
- Insidious, dry, scaly skin lesions lacking sensation, peripheral nerve involvement and local anesthesia with skin and muscle atrophy that increase risk of chronic ulcers and autoamputation.
13
Q
Lepromatous (anergic) Leprosy
A
- Relatively ineffective TH2 response.
- Large collections of lipid-laden macrophages overstuffed with bacilli.
- Disfiguring cutaneous thickening and nodules, with nervous system damage due to mycobacterial invasion into perineural macrophages and Schwann cells.
- TESTES are extensively involved = STERILITY.
14
Q
Spirochetes
A
- Gram-negative, corkscrew-shaped bacteria with flagella.
15
Q
Syphillis
A
- Treponema pallidum (venereal or transplacental)
- Delayed TH1 hypersensitivity.
