Chapter 6 – Bacteria and Bacterial Infections Flashcards
1
Q
What type of cells are bacteria?
A
Prokaryotes, a class of unicellular life.
2
Q
What are the two domains of bacteria?
A
Archaebacteria and Eubacteria.
3
Q
Why are bacteria highly successful organisms?
A
They are adaptable and inhabit every environmental niche.
4
Q
What is the main structural difference between prokaryotic and eukaryotic cells?
A
Prokaryotic Cells: lack a nucleus and membrane-bound organelles.
Eukaryotic Cells: have a nucleus and organelles like mitochondria, ER, Golgi bodies.
5
Q
What is the nucleoid in prokaryotic cells?
A
Chromosomal region that contains genetic material, not enclosed by a membrane.
6
Q
What is the function of the bacterial cell wall?
A
Made of peptidoglycan, provides mechanical support and prevents the cell from collapsing due to osmotic pressure changes.
7
Q
What are flagella?
A
Provide bacterial motilitiy.
8
Q
What are pili?
A
Aid in bacterial surface adhesion and genetic exchange.
9
Q
What are fimbriae?
A
Help bacteria attach to surfaces.
10
Q
What are glycocalyx?
A
Protects bacteria from phagocytosis.
11
Q
How do bacteria reproduce?
A
By binary fission, where the single circular chromosomal DNA is copied and distributed into two progeny cells.
12
Q
What are plasmids?
A
Small, extra-chromosomal DNA molecules in bacteria that carry additional genes and can be transmitted between bacterial cells.
13
Q
What factors influence bacterial growth rate?
A
Nutrient availability, temperature, pH, osmolarity.
14
Q
How are bacteria identified in a lab?
A
Identified using differential culture media that restrict or provide specific nutrients, and by examining colony growth patterns on agar plates or in nutrient broth.
15
Q
What are endospores, and why are they important?
A
Highly durable bacterial structures that allow bacteria to survive harsh conditions (e.g., extreme temperatures, drying).
16
Q
What do endospores grow into?
A
When conditions are permissive, they germinate into vegetative bacterial cells.
17
Q
What are the main criteria for bacterial classification?
A
- Gram Staining (e.g., gram-positive or gram-negative).
- Cell Shape
- Special Features (e.g., pathogenicity, antibiotic resistance).
18
Q
What does gram staining indicate?
A
Reflects differences in bacterial cell wall structure.
1. Gram-positive: thick peptidoglycan layer, purple.
2. Gram-negative: thin peptidoglycan layer, pink.
19
Q
Bacterial Shapes – Cocci
A
- Cocci: spherical
- Diplococci: paired
- Streptococci: chains
- Staphylococci: clusters
20
Q
Bacterial Shapes – Bacilli
A
- Bacilli: rod-shaped
- Diplobacilli: paired
- Streptobacilli: chains
- Palisades: clusters
21
Q
Bacterial Shapes – Vibrio
A
Comma-Shaped
22
Q
Bacterial Shapes – Spirochaete
A
Spiral-Shaped
23
Q
What are opportunistic pathogens?
A
Harmless but can cause infections in immunocompromised individuals.
24
Q
What are true pathogens?
A
Virulent and capable of causing disease in healthy hosts.
25
How do bacteria resist phagocytosis?
Glycocalyx, Digestive Enzymes, Toxin Production, Intracellular Survival
26
What factors determine the extend of tissue injury caused by bacteria?
1. Number of bacteria present
2. Virulence of bacteria (e.g., type of toxins it contains)
3. Site of infestation
4. Resistance of the tissue
27
What are the main chemical classes of bacterial toxins?
1. Proteins (exotoxins)
2. Lipopolysaccharides (endotoxins)
28
What is the traditional classification of bacterial toxins?
1. Exotoxins (associated w/ gram-positive and gram-negative)
2. Endotoxins (associated w/ gram-negative)
29
How do bacterial toxins cause damage in the body?
Diffuse into blood and body fluids, acting as sites distant from bacterial proliferation, promoting bacterial growth and tissue invasion.
30
What is Staphylococcus Aureus, and where is it found?
A major bacterial pathogen, found in hospitals and clinical settings. One of the most resistant non-spore producing bacteria.
31
What infections can Staphylococcus Aureus cause?
Boils, Impetigo, Wound Infections, Pneumonia, Osteomyelitis, Endocarditis
32
What are the virulence factors of Staphylococcus Aureus?
1. Coagulase (e.g., blood and plasma)
2. Hemolysin (e.g., RBCs, muscle, heart, kidney cells)
3. Release Toxins causing (e.g., Staphylococcal food poisoning, Staphylococcal Scalded Skin Syndrome, Toxic Shock Syndrome)
33
How does Staphylococcus Aureus spread?
Because they are found on fomites (inanimate objects e.g., door handles, faucets).
34
Why is Staphylococcus Aureus hard to treat?
They are resistant to a range of antibiotics. For example, they produce B-Lactamase, which breaks down penicillin, acquiring resistance to methicillin, oxacillin, and cephalothin.
35
What is Staphylococcus Epidermidis, and why is it significant?
A bacterium found in the nares, skin, vagina, and gut. They are opportunistic pathogens and are a common cause of nosocomial infections, associated with catheters and medical devices.
36
What are streptococci, and how are they classified?
Spherical bacteria that form bead-like chains. They are classified by virulence into Groups A, B, C, and G Streptococci, and Streptococcus Pneumoniae.
37
What infections are caused by Group A Streptococcus?
Pharyngitis, Tonsillitis, Skin and Soft Tissue Infections (e.g., S. Pyogenes can cause rheumatic fever, glomerulonephritis).
38
What are the virulence factors of S. Pyogenes?
Hemolysin (e.g., RBCs), Pyrogenic Toxin (e.g., induces fever and inflammation).
39
What infections are caused by Group B Streptococci?
Colonizes the gut and genital tract. Can cause life-threatening neonatal meningitis and septicemia.
40
What infections are caused by Group C and G?
Pharyngitis.
41
What is Streptococcus Pneumoniae, and what does it cause?
Pneomoccocus, leading cause of pneumonia.
42
How are Streptococcus infections treated?
With penicillin, however, resistance to tetracycline.
43
What is Neisseria Gonnorrhoeae, and how is it transmitted?
Gram-negative coccus found in humans, transmitted through sexual contact (e.g., vaginal and anal intercourse). Gonorrhea is one of the top five STIs.
44
What are the symptoms and complications of gonorrhea?
Acute Urethritis (more apparent in men), Pelvic Inflammatory Disease, Uterine & Fallopian Infections, Infertility, Mouth & Rectum Infections.
45
What is Neisseria Meningitidis, and what does it cause?
A gram-negative coccus, causing epidemic meningitis, which is a fatal infection of the meninges.
46
What is Corynebacterium Diphtheriae, and what disease does it cause?
A gram-positive rod, causing diphtheria, a severe respiratory disease.
47
How is diphtheria transmitted?
It is spread by respiratory aerosol, and asymptomatic human carriers serve as reservoirs.
48
What is a pseudomembrane?
A dense, grey layer in the pharynx composed of dead tissue, fibrin, blood cells, and bacteria leading to respiratory obstruction, due to diphtheria.
49
What are the complications of diphtheria?
Produces a potent exotoxin that causes myocarditis, neurological effects, and peripheral vascular collapse.
50
What is Bacillus Anthracis, and what does it cause?
A gram-positive rod, causing the infection, anthrax.
51
Where is Bacillus Anthracis found, and how is it transmitted?
It is found in soil and forms tough, resistant endospores and is transmitted from animals to humans.
52
What are the three forms of anthrax?
1. Cutaneous: affecting the skin.
2. Gastrointestinal: affecting the GI tract.
3. Pulmonary: affecting the respiratory tract, most dangerous as it has high exotoxin production.
53
What are Clostridia, and where are they commonly found?
A gram-positive, spore forming anaerobe found in soil, thriving in low oxygen environments (e.g., deep tissues in the body).
54
What is unique about Clostridia toxins?
They produce exotoxins, the most potent toxins known.
55
What is Clostridium Perfringens, and what does it cause?
A gram-positive anaerobe that rapidly leads to septic shock and death. It causes tissue destruction – myonecrosis and gas gangrene.
56
What are the risk factors for Clostridium Perfringens?
Septic Abortion, Crushing Injuries, Compound Fractures, Gunshot and Knife Wounds, Malignancies.
57
What is Clostridium Botulinum, and what does it cause?
A gram-positive anaerobe that causes food poisoning, where they enter bent/cracked cans in low-oxygen environments.
58
What does Clostridium Botulinum produce?
It produces botulinum toxin, one of the most toxic substances known.
59
How does the Botulinum toxin cause harm?
It binds to presynaptic cholinergic nerves at the NMJ, preventing the release of acetylcholine, leading to skeletal muscle paralysis, and respiratory failure.
60
What is Clostridium Tetani, and what does it cause?
A gram-positive anaerobe that is the causative agent of tetanus. It is found in soil and the GI tract and causes infection by entering cuts or penetrating wounds.
61
What does Clostridium Tetani produce?
It produces an exotoxin, tetanospasmin.
62
How does Tetanospasmin cause harm?
It targets the terminal synapse of the NMJ, inhibiting the release of glycine and GABA, resulting in spastic paralysis.
63
What is Pseudomonas Aeruginosa?
A gram-negative rod aerobic bacteria. It is an opportunistic pathogen affecting the lungs, skin, eyes, and ears.
64
Why is Pseudomonas Aeruginos clinically significant?
They are common in immunocompromised individuals and are a common cause of nosocomial infections. They have a grapey odour and a fluorescent green-blue colour.
65
What is Escherichia Coli (E. Coli), and what does it cause?
A gram-negative rod, part of the normal gut flora that is an indicator of fecal contamination in food and water. It causes UTIs, diarrhea, and kidney infections.
66
What is E. Coli strain O157:H7?
A strain that produces the exotoxin, Shiga toxin. It is transmitted via contaminated food and causes hemorrhagic diarrhea. In immunocompromised individuals, it can cause Hemolytic Uremic Syndrome, leading to kidney failure.
67
What is Salmonella Enterica, and what does it cause?
A gram-negative rod that causes Typhoid fever.
68
What is Typhoid fever?
A diarrheal disease transmitted via fecal-oral route through contaminated food and water. It attacks the liver and can lead to diarrhea, septicemia, ulcerated intestine, peritonitis, septic shock and death.
69
Why is Typhoid fever significant?
A major epidemic disease throughout history and are eradicated in developed nations via improved sanitation and food safety regulations. It is common in war zones and impoverished areas.
70
What is Brucella, and what does it cause?
A gram-negative bacteria that causes Brucellosis, a zoonotic infection (from animals to humans). It is transmitted via direct animal contact, inhalation of aerosols where animals are present, and consumption of contaminated animal products.
71
What are the symptoms and complications of Brucellosis?
It causes undulating fever, headache, joint pain, night sweats, fatigue, anorexia and can lead to endocarditis, liver abscess, neurological damage.
72
What is Bordetella Pertussis, and what does it cause?
A gram-negative bacteria that causes whooping cough, a highly contagious cough that spreads via respiratory droplets and produces pertussis toxin.
73
What is Yersinia Pestis, and what does it cause?
A gram-negative bacteria that causes plague. It is transmitted to humans by fleas from infected rats.
74
What happens after a flea transmits Yersinia Pestis?
The bacteria colonizes local lymph nodes (e.g., axilla, groin, cervical) and forms lymphadenopathy, which are painful, swollen pustules that erupt. This can lead to fever, cramps, malaise, seizures, vomiting, or death.
75
What are Acid-Fast Bacteria?
Bacteria with unique staining properties that contain mycolic acid in their cell wall. They resist destruction by phagocytes and divide and spread slowly, making it difficult to culture.
76
Where are two examples of Acid-Fast Human Pathogens?
1. Myobacterium Tuberculosis
2. Myobacterium Leprae
77
What is Tuberculosis (TB), and why is it a global health challenge?
A highly prevalent infectious disease, affecting one-quarter of the world's population. Common in areas of poverty and overcrowding, closely linked to HIV.
78
What bacterium causes Tuberculosis?
The Mycobacterium Tuberculosis Complex consisting of M. Tuberculosis, M. Bovis, M. Africanum, M. Canetti, and M. Microti.
79
How is Tuberculosis transmitted?
It is spread through respiratory aerosols (e.g., cough, sputum) and the ingestion of unpasteurized milk.
80
What is Primary Tuberculosis?
Occurs when TB bacteria colonize the lungs and survive within macrophages, leading to chronic inflammation with granulomas and caseous necrosis. It can be silent or cause symptoms like fatigue, cough, fever, night sweats, and weight loss.
81
What is Secondary TB?
Occurs when a latent infection reactivates, causing severe lung damage, fibrosis, or pulmonary hemorrhage.
82
What is Extra-Pulmonary TB?
Occurs when TB spreads beyond the lungs and into other tissues.
83
What is Miliary TB?
Occurs when TB granulomas form throughout many organs (e.g., bone, brain, kidneys, ovaries).
84
What test is used for screening latent TB?
The Mantoux Test (tuberculin skin test), which assesses cellular immunity – Hypersensitivity Type IV.
85
How is active TB diagnosed?
Through chest radiography (radio-dense granulomas), microbiological analysis of sputum or other fluids (including culturing and DNA analysis).
86
What is the treatment regimen for TB?
A three-month course of isoniazid along with rifampicin or rifapentine.
87
What is the causative agent of Leprosy (Hansen's Disease)?
Mycobacterium Leprae.
88
How does Leprosy differ from Tuberculosis?
Leprosy affects peripheral tissues (e.g., nerves, skin, eyes, mucosa), while TB affects the lungs.
89
How is Leprosy transmitted?
It is spread through respiratory aerosols, requiring repeated contact in genetically susceptible individuals.
90
What is the incubation period for Leprosy?
3 to 5 years.
91
What are the early signs of Leprosy?
Loss of sensation, pale skin lesions (e.g., macules, papules), thickened nerves with loss of motor strength.
92
How is Leprosy classified?
1. Paucibacillary: < 5 skin patches.
2. Multibacillary: > 5 skin patches.
93
How is Leprosy diagnosed?
Through acid-fast staining of skin lesion samples, and DNA detection of M. Leprae from lesions.
94
What is the treatment regimen for Leprosy?
A six-month combo therapy with rifampicin, dapsone, clofazimine.
95
What are Spirochetes?
They are gram-negative, helical-shaped rods with filaments around the cell wall that help move them through aqueous environments.
96
What are the three main genera of Spirochetes?
1. Leptospira
2. Borrelia
3. Treponema
97
What are Leptospira Spp.?
Zoonotic pathogens that are carried by wild and domestic animals. They are shed in the urine of infected animals and survive in moist environments.
98
How is Leptospira Spp. transmitted to humans?
Through direct or indirect contact with urine-contaminated environments (e.g., water, soil, food). Risk factors include flooding, urban slums, occupations with animal exposure.
99
What are signs and symptoms of Leptospirosis?
Fever, muscle pain, pulmonary hemorrhage, meningitis, acute kidney injury, Weli's disease.
100
What are some pathogenic species of Leptospira?
L. Interrogans, L. Noguchii, L. Kirschneri, and L. Santarosai.
101
How is Leptospira Spp. diagnosed?
Clinical history and serological tests.
102
What is the treatment for Leptospirosis?
If it doesn't go away on it's own, taking doxycycline.
103
What is the causative agent of Lyme disease?
A spirochete bacterium, Borrelia Burgdorferi.
104
How is Lyme disease transmitted?
It is transmitted by lxodes ticks, which are on infected animals (e.g., deer, mice). It enters the body through tick bites.
105
What are the signs and symptoms of Lyme disease?
Eryhtema migrans rash, flu-like symptoms, joint pain.
106
What are the later complications of untreated Lyme disease?
Disseminated infection, neurological involvement (e.g., leptomeningitis, encephalitis, changes in CSF).
107
How is Lyme disease diagnose?
Through clinical history, symptoms, and serological tests.
108
What is the treatment regimen for Lyme disease/
Taking antibiotics (e.g., doxycycline, azithromycin, amoxicillin).
109
What is the causative agent of Syphilis?
The spirochete bacterium, Treponema Pallidum.
110
How is Syphilis transmitted?
Through sexual contact with mucosal lesions containing T. Pallidum, or vertical transmission (from mother to child).
111
What is Primary Syphilis?
At the side of contact, a red papule becomes a painless chancre (e.g., genitals, anus, rectum, mouth). It then releases a fluid containing spirochetes.
112
What is Secondary Syphilis?
Once the spirochetes distribute to lymph nodes, it leads to skin rash, swollen lymph nodes, and fever.
113
What is Latent Syphilis?
The bacteria remains in the body and there are no symptoms. It may remain latent or progress to the tertiary stage.
114
What is Tertiary Syphilis?
The infection spreads to organs (e.g., brain, heart, aorta) and causes complications like aortic aneurysm, meningitis, retinitis, bone pain.
115
How is Syphilis diagnosed?
Through clinical findings and serological tests (e.g., nontreponemal tests for screening, treponemal tests for confirmation).
116
What is the treatment for Syphilis?
Through Penicillin G, and Doxycycline or Azithromycin.
