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Clinical Microbiology > Chapter 18: Haemophilus and Other Fastidious Gram-Negative Bacilli > Flashcards

Chapter 18: Haemophilus and Other Fastidious Gram-Negative Bacilli Flashcards

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1
Q

What are the characteristics of Haemophilus?

A

Tiny Gram negative coccobacillus, may form filaments, facultative anaerobes, oxidase positive, optimal growth in 5%-10% CO2, fastidious, susceptible to drying and temperature extremes, require hematin and NAD for in vitro growth.

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2
Q

What factors do Haemophilus species require for growth?

A

X and V factors

X factor is hemin, hematin; V factor is nicotinamide-adenine dinucleotide (NAD)

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3
Q

Which Haemophilus species requires only the V factor?

A

H. parainfluenzae

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4
Q

What is the significance of chocolate agar for Haemophilus species?

A

Chocolate agar releases X and V factor and deactivates NADases.

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5
Q

Define satellitism in the context of Haemophilus growth.

A

Growth of fastidious organisms around other bacteria that release necessary growth factors.

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6
Q

What are the virulence factors of H. influenzae?

A

Capsule, immunoglobulin A (IgA) protease, outer membrane proteins, lipopolysaccharide (LPS), adherence structures.

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7
Q

What diseases are caused by H. influenzae?

A

Meningitis, epiglottitis, bacterial tracheitis, cellulitis, acute pharyngitis, pneumonia.

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8
Q

What is the incubation period for Legionnaires’ disease?

A

2 to 10 days

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9
Q

What are the symptoms of Legionnaires’ disease?

A

Nonproductive cough, fever, headache, myalgia, progressing to bloody or purulent sputum, difficulty breathing.

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10
Q

What is the primary species of Bordetella responsible for whooping cough?

A

B. pertussis

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11
Q

How is Bordetella pertussis transmitted?

A

Via contaminated droplets (talking, coughing, sneezing, laughing).

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12
Q

What type of colonies does Bordetella pertussis form?

A

Smooth silver pinpoint colonies resembling mercury droplets.

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13
Q

What is the primary characteristic of Vibrio cholerae?

A

Causes cholera through an exotoxin, resulting in voluminous rice-water diarrhea.

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14
Q

What are the identifying features of Vibrio species?

A

Facultatively anaerobic, small, straight, gram-negative rods, catalase and oxidase positive.

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15
Q

What is the most common diarrheal illness worldwide?

A

C. jejuni infection

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16
Q

What is Helicobacter pylori associated with?

A

Chronic superficial gastritis, ulcers, gastric carcinoma.

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17
Q

What is a common characteristic of nonfermenting gram-negative bacilli?

A

Do not ferment sugars, oxidize sugars.

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18
Q

What is the leading cause of nosocomial respiratory tract infections?

A

P. aeruginosa

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19
Q

What virulence factors are associated with P. aeruginosa?

A

Endotoxins, exotoxins, motility, pili, proteases, hemolysin, capsule.

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20
Q

What is the significance of the matrix-associated laser desorption-ionization time-of-flight (MALDI-TOF) method?

A

Used for definitive identification of bacteria and fungi based on unique peptide spectra.

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21
Q

What are the characteristics of anaerobes?

A

Prevalent in the environment, normal microbiota of human body, important human pathogens.

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22
Q

What is the difference between exogenous and endogenous infections?

A

Exogenous: external source; Endogenous: commensal sources displaced through surgery or trauma.

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23
Q

What is the source of exogenous infections?

A

External infection source

Examples include Clostridium botulism and C. tetani.

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24
Q

What are endogenous infections?

A

More common sources of infection

These include commensal sources displaced through surgery or trauma.

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25
Which bacterium is associated with abdominal abscess?
Bacteroides fragilis ## Footnote This bacterium is a common anaerobic organism.
26
Name a few anaerobes found in the skin.
* Propionibacterium acnes * Peptostreptococcus ## Footnote These are common skin flora.
27
Which anaerobes are found in the respiratory tract?
* Prevotella * Porphyromonas * Fusobacterium * Anaerobic cocci ## Footnote These bacteria are part of the normal flora but can cause infections.
28
What are the common anaerobes in the gastrointestinal tract?
* Bacteroides * Bifidobacterium * Clostridium * Eubacterium ## Footnote They are part of the normal gut flora.
29
List the anaerobes found in the genitourinary tract.
* Fusobacterium * Prevotella * Bacteroides * Lactobacillus * Anaerobic cocci ## Footnote These species can be involved in infections.
30
What factors predispose patients to anaerobic infections?
* Trauma to protective barriers * Vascular stasis * Prevention of oxygen flow to site * Bite wounds * Aspiration of oral flora into deep lung * Oral surgery * Wounds or burns with soil contamination ## Footnote These factors create an anaerobic environment conducive to infection.
31
Which genera of bacteria are frequently encountered anaerobes?
* Clostridium * Bacteroides * Fusobacterium * Prevotella * Porphyromonas * Veillonella * Peptococcaceae ## Footnote These genera are significant in clinical microbiology.
32
What is the shape and gram stain of Clostridium perfringens?
Boxcar-shaped, gram-negative bacillus ## Footnote It produces a double zone of hemolysis on Brucella blood agar.
33
What is the clinical significance of Clostridium difficile?
Reclassified as Clostridiodes difficile, associated with antibiotic-associated diarrhea and pseudomembranous colitis ## Footnote It is a major cause of hospital-acquired infections.
34
What are the diseases caused by Clostridium spp.?
* Tetanus (Clostridium tetani) * Gas gangrene (Clostridium perfringens) * Botulism (Clostridium botulinum) * Other food poisoning ## Footnote These diseases are known for their severity and clinical impact.
35
What is the purpose of using methanol as a fixative in gram staining?
To recognize morphology with presumptive identification ## Footnote It helps preserve the structure of the bacteria.
36
What is the role of anaerobic media in microbiology?
Isolation of anaerobic bacteria ## Footnote Examples include PEA, KV, PVLB, Thioglycollate, BBE, and CCFA.
37
What is the primary method for identifying anaerobic bacteria?
Gram stain and gross examination ## Footnote This includes detecting putrid odors and colonial morphology.
38
What are spirochetes?
Helical-shaped, motile bacteria ## Footnote They exhibit various types of motion in liquid media.
39
What disease is caused by Treponema pallidum subsp. pallidum?
Syphilis ## Footnote It is a sexually transmitted infection.
40
Which vector is associated with Borrelia recurrentis?
Pediculus humanus humanus (human body louse) ## Footnote It is responsible for louse-borne relapsing fever.
41
What is a classic symptom of Lyme borreliosis?
Erythema chronicum migrans: classic 'bulls-eye rash' ## Footnote This occurs in about 60% of patients.
42
What is the incubation period for syphilis?
10 to 90 days, usually about 3 weeks ## Footnote This period is crucial for diagnosis.
43
What are nontreponemal tests used for in syphilis screening?
To detect reagin, an antibody-like substance ## Footnote Tests include RPR and VDRL.
44
What is the preferred treatment for syphilis?
Penicillin, specifically Benzathine penicillin ## Footnote Alternatives include doxycycline and tetracycline for penicillin allergies.
45
What are the characteristics of Chlamydiaceae?
* Obligate intracellular parasites * Gram-negative type cell wall * Can synthesize proteins, lipids, nucleic acids * Multiply by binary fission ## Footnote They require host cells for growth.
46
How is Rocky Mountain spotted fever transmitted?
By ticks, specifically D. variabilis and D. andersoni ## Footnote Humans are accidental hosts.
47
What diseases are caused by Mycoplasma pneumoniae?
Respiratory disease ## Footnote It is one of the two known human pathogens in the Mycoplasma genus.
48
What is the general characteristic of Mycobacteria?
Nonmotile, slender, slightly curved, rod-shaped bacilli; non-spore-forming ## Footnote They have a high lipid content in their cell wall.
49
What is the treatment duration for tuberculosis?
9-month course of therapy ## Footnote Includes isoniazid and rifampin, with possible addition of other drugs.
50
What is the duration of the recommended therapy course for tuberculosis?
9-month course of therapy ## Footnote This typically includes multiple antibiotics.
51
Which antibiotics are included in the standard tuberculosis treatment?
Isoniazid and rifampin ## Footnote These are the primary drugs used.
52
What additional antibiotics may be used in tuberculosis treatment for 2- to 8-weeks?
Streptomycin or ethambutol ## Footnote These may be included depending on the patient's condition.
53
Which drug may be used if there is lowered cellular immunity in tuberculosis patients?
Pyrazinamide (PZA) ## Footnote This drug helps enhance the treatment outcome.
54
What should be done if tuberculosis bacteria are resistant?
Use combination therapy ## Footnote This approach helps to combat drug resistance.
55
What are some alternative drugs used if tuberculosis is resistant?
Kanamycin, ciprofloxacin ## Footnote These drugs are used in cases of resistance.
56
True or False: Resistance in tuberculosis develops more rapidly with the use of single drugs.
True ## Footnote This highlights the importance of combination therapy.
57
Name three key characteristics of Haemophilus influenzae.
1. Gram-negative 2. Coccobacillus 3. Causes respiratory infections ## Footnote Important to understand its role in human disease.
58
What are the key characteristics of Legionella pneumophila?
1. Gram-negative 2. Rod-shaped 3. Causes pneumonia ## Footnote Recognized for its association with water systems.
59
What is a key characteristic of Bordetella pertussis?
Causes whooping cough ## Footnote This bacterium is known for its highly contagious nature.
60
What are the key characteristics of Vibrio cholerae?
1. Gram-negative 2. Comma-shaped 3. Causes cholera ## Footnote It is linked to contaminated water.
61
Name a key characteristic of Campylobacter jejuni.
Causes gastroenteritis ## Footnote Often associated with undercooked poultry.
62
What is a key characteristic of Helicobacter pylori?
Causes peptic ulcers ## Footnote This bacterium is significant in gastrointestinal health.
63
What is a key characteristic of Pseudomonas aeruginosa?
Opportunistic pathogen ## Footnote Known for causing infections in immunocompromised individuals.
64
What are key characteristics of anaerobes, specifically Clostridium spp.?
1. Gram-positive 2. Spore-forming 3. Can cause severe infections ## Footnote Important to recognize in clinical settings.
65
What is a key characteristic of Borrelia spp.?
Causes Lyme disease ## Footnote Transmitted by ticks, significant for public health.
66
What is a key characteristic of Treponema pallidum?
Causes syphilis ## Footnote This spirochete is important in sexually transmitted infections.
67
What is a key characteristic of Chlamydia trachomatis?
Causes chlamydia ## Footnote It is one of the most common STIs worldwide.
68
What is a key characteristic of Rickettsiae spp.?
Intracellular parasites ## Footnote Known for causing typhus and spotted fevers.
69
What is a key characteristic of Mycoplasma spp.?
Lack a cell wall ## Footnote Important in atypical pneumonia.
70
What is a key characteristic of Mycobacterium tuberculosis?
Causes tuberculosis ## Footnote Known for its resistance to many antibiotics.

Clinical Microbiology (22 decks)

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