Microbiology: Pseudomonas and Legionella

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Questions and Answers

What is the preferred treatment for B. Fragilis infections?

Metronidazole (correct)

Vancomycin

Ciprofloxacin

Amoxicillin

Which Pseudomonas species is predominantly found in clinical settings?

Burkholderia mallei

P. putida

P. fluorescens

P. aeruginosa (correct)

Which type of infections is commonly associated with P. aeruginosa?

Skin infections in healthy individuals

Viral infections in the elderly

Pneumonia in cystic fibrosis patients (correct)

Stomach flu in children

What is a characteristic property of Pseudomonas species?

They are non-fermenters of glucose. Signup and view all the answers

What type of infections can commonly lead to sepsis caused by Pseudomonas?

Systemic infections including CNS and endocarditis Signup and view all the answers

What kind of organisms are common in the human colon that are resistant to antibiotics?

B. Fragilis Signup and view all the answers

In which patients is P. aeruginosa most commonly associated with wound infections?

Burn patients Signup and view all the answers

What environmental conditions do Pseudomonas species thrive in?

Plain water with very little nutrition Signup and view all the answers

What is a significant clinical outcome of systemic Pseudomonas infections?

50% lethality in sepsis cases Signup and view all the answers

Which type of pneumonia is associated with Legionella pneumophila?

Atypical pneumonia Signup and view all the answers

What is the main virulence factor of Legionella pneumophila?

Lipopolysaccharide (endotoxin) Signup and view all the answers

How is Legionella pneumophila primarily acquired?

Inhalation of aerosols Signup and view all the answers

Which group is typically more susceptible to Legionnaire's disease?

Immunocompromised patients Signup and view all the answers

Which of the following is a characteristic of Pontiac Fever?

Spontaneous recovery Signup and view all the answers

Which diagnostic test is used for Legionnaire's disease?

Urinary antigen test Signup and view all the answers

What is Brucellosis also known as?

Undulant fever Signup and view all the answers

What type of bacteria is Brucella classified as?

Coccobacillus Signup and view all the answers

Where do Brucella bacteria localize in the body?

Reticuloendothelial system Signup and view all the answers

What is a common risk factor for developing Legionnaire's disease?

Kidney disease Signup and view all the answers

What is the primary treatment for competent individuals with severe localized abscesses caused by Yersinia Pestis?

Azithromycin Signup and view all the answers

Which virulence factor of Yersinia Pestis helps block phagocytosis?

Capsular antigen (F-1) Signup and view all the answers

What is the ID50 of Yersinia Pestis, making it particularly dangerous?

1-10 organisms Signup and view all the answers

How is Yersinia Pestis primarily transmitted from rodent hosts to humans?

Bites from infected fleas Signup and view all the answers

What characteristic describes Bubonic plague in terms of its clinical findings?

Cells accumulate in the bloodstream and localize in lymph nodes Signup and view all the answers

Which factor contributes to the pathogenesis of Yersinia Pestis in its flea vector?

Biofilm formation in the upper GI tract Signup and view all the answers

What is a major clinical manifestation of Septicemic plague?

Abscesses and intravascular coagulation Signup and view all the answers

Which factor does NOT contribute to Yersinia Pestis's ability to facilitate intracellular growth?

Endotoxin Signup and view all the answers

What was the historical name for Septicemic plague during the 14th century in Europe?

The Black Death Signup and view all the answers

What is a potential mode of transmission of pneumonic plague among humans?

Inhalation of respiratory droplets from infected individuals Signup and view all the answers

What is the most common cause of atypical pneumonia?

Pneumonia Signup and view all the answers

Which of the following is NOT a symptom associated with atypical pneumonia?

Shortness of breath Signup and view all the answers

Which complication is NOT typically associated with pneumonia?

Sepsis Signup and view all the answers

What type of treatment can shorten the course of atypical pneumonia?

Macrolides Signup and view all the answers

What is a recognized symptom of Ureaplasma Urealyticum infection in women?

Endometritis Signup and view all the answers

How is M. Genitalium most commonly diagnosed?

PCR tests Signup and view all the answers

Which drug combination is primarily recommended for treating dapsone-resistant infections?

Dapsone + rifampin + clofazimine Signup and view all the answers

What is a characteristic feature of Actinomyces israelii infections?

Yellow 'sulfur' granules in draining pus Signup and view all the answers

Which characteristic is true for Mycoplasma pneumoniae?

Does not gram stain due to lack of a cell wall Signup and view all the answers

Nocardia asteroides infections are primarily associated with which of the following sources?

Soil Signup and view all the answers

Which of the following conditions can prolonged IUD retention lead to?

Pelvic actinomycosis Signup and view all the answers

What is the primary mode of transmission for Mycoplasma pneumoniae?

Respiratory droplets Signup and view all the answers

What percentage of community-acquired pneumonia is caused by Mycoplasma pneumoniae, particularly among young adults?

10-20% Signup and view all the answers

What type of bacteria are actinomycetes classified as?

Gram-positive and filamentous Signup and view all the answers

Which feature distinguishes Mycoplasmas from other bacteria?

Cell membrane containing cholesterol Signup and view all the answers

Which condition is NOT caused by Mycoplasma pneumoniae?

Abscesses in lungs Signup and view all the answers

Study Notes

Pseudomonas

Most commonly encountered species is Pseudomonas aeruginosa.
Found in soil, water, moist skin, and occasionally the colon.
Causes various diseases associated with weakened immunity and low neutrophil counts.
Pseudomonas aeruginosa is a major nosocomial pathogen.
Pseudomonas aeruginosa is an obligate aerobe (oxidase-positive and non-fermenter of glucose, except for Pseudomonas aeruginosa), and can grow in plain water with minimal nutrition.

Legionella Pneumophila

Intracellular parasites that can live in amoebas in nature and macrophages during infection.
Anerobic; lipopolysaccharide is the main virulence factor.
Found in areas where water collects and in soil; can become airborne in the wind or ventilation systems.
Resistant to chlorine.
Acquired by inhaling aerosols; not transmitted person-to-person (humans are dead-end hosts).
Alveolar macrophages consume Legionella pneumophila for defense, but the bacteria then multiply within them.

Brucella (Brucellosis = undulant fever)

Coccobacillus lacking a capsule.
Aerobic; LPS is the main virulence factor.
Intracellular in macrophages; localizes to the reticuloendothelial system (lymph nodes, liver, spleen, bone marrow = connective tissue macrophages).

Yersinia Pestis (Plague)

Small rod-shaped bacteria with bipolar staining; intracellular.
Extremely low infectious dose (1-10 organisms); potential bioweapon.
Transmitted among rodents via fleas; humans are accidental hosts after being bitten by infected fleas.
Two epidemiological cycles:
- Sylvatic cycle: Wild rodents (especially prairie dogs in the U.S.)
- Urban cycle: Rats in the city (not currently found in the U.S.)
Respiratory droplet transmission can occur from patients with pneumonic plague.
Forms a biofilm in the upper gastrointestinal tract of the flea, preventing nourishment; the starving blocked flea bites more hosts and regurgitates bacteria.

Actinomycetes

Filamentous, resembling fungi.
Gram-positive; some are weakly acid-fast.

Actinomyces Israeli

Normal oral microbiota; invades after trauma or poor dental hygiene.
Yellow "sulfur" granules (masses of filaments) in draining pus.
50% of cases occur in the face and neck; the remainder in the chest or abdomen.
Prolonged retention of intrauterine devices (IUDs) can lead to pelvic actinomycosis.

Nocardia Asteroides

Primarily found in soil; inhaled or enters through wounds.
Can infect immunocompromised lungs, causing abscesses and pneumonia, and then disseminate.

Mycoplasmas

Among the smallest bacteria known.
Lack a cell wall; thus, cell wall-targeting antibiotics are ineffective.
Can change shape.
Do not stain with Gram stain.
Cell membrane contains cholesterol, which stiffens it, as in eukaryotes.
Cause problems in laboratory tissue cultures of eukaryotic cells.
M.Pneumoniae is pathogenic only in humans.

M.Pneumoniae (Atypical Pneumonia)

Transmitted by respiratory droplets.
Has adhesions for ciliated bronchial epithelium.
Produces an exotoxin similar to that of pertussis.
Causes inflammation and necrosis; inhibits ciliary motion.
Causes 10-20% of community-acquired pneumonia, especially among young adults in close quarters.
More frequent in the fall and winter.
Autoantibodies against red blood cells, brain, lung, and liver can form during infection.

Genital Mycoplasmas (Found in Urogenital Tract)

M. Hominis causes postpartum fever and pelvic inflammatory disease.
Ureaplasma urealyticum causes non-gonococcal urethritis. In women, it can cause endometritis and is associated with premature labor and delivery.
M. Genitalium is sexually transmitted; causes non-gonococcal urethritis in men. In women, it causes cervical inflammation and pelvic inflammatory disease. Diagnosed by PCR.

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Description

This quiz focuses on the characteristics and pathogenicity of Pseudomonas aeruginosa and Legionella pneumophila. You will explore their environments, modes of transmission, and impact on human health. Evaluate your understanding of these important microorganisms prevalent in various settings.