Module 9 2.Patho: Describes the four main classes of infectious microorganism: Bacteria

Question 1

What are bacteria?

Answer 1

Bacteria are prokaryotic microorganisms lacking a discrete nucleus and are relatively small in size.

Question 2

What are the different characteristics exhibited by bacteria?

Answer 2

Bacteria can be aerobic (requiring oxygen) or anaerobic (not requiring oxygen), and motile (capable of movement) or immotile (non-motile).

Question 3

What are cocci, bacilli, and spirochetes in relation to bacteria?

Answer 3

These are different shapes of bacteria, with cocci being spherical, bacilli being rod-shaped, and spirochetes being spiral-shaped.

Question 4

How is the Gram stain used in microbiology?

Answer 4

The Gram stain technique is used to differentiate bacteria into two categories, Gram-positive and Gram-negative, based on their cell wall structure.

Question 5

What are some common upper respiratory tract infections caused by bacteria?

Answer 5

Examples include Corynebacterium diphtheriae, Haemophilus influenzae, and Streptococcus pyogenes.

Question 6

Which bacteria are associated with otitis media, an infection of the ear?

Answer 6

Haemophilus influenzae and Streptococcus pneumoniae.

Question 7

Name a bacterium responsible for lower respiratory tract infections.

Answer 7

Bacillus anthracis (pulmonary anthrax) and Bordetella pertussis (whooping cough) are examples.

Question 8

Which bacteria cause gastro-intestinal infections, and how are they categorized?

Answer 8

Inflammatory gastro-intestinal infections can be caused by Bacillus anthracis, Clostridium difficile, Escherichia coli O157:H7, and Vibrio cholerae. Invasive gastro-intestinal infections are associated with Brucella abortus, Helicobacter pylori, Listeria monocytogenes, Salmonella typhi, and Shigella sonnei.

Question 9

What bacteria are responsible for food poisoning?

Answer 9

Bacillus cereus, Clostridium botulinum, Clostridium perfringens, and Staphylococcus aureus can cause food poisoning.

Question 10

Which bacteria are associated with sexually transmitted infections?

Answer 10

Chlamydia trachomatis, Neisseria gonorrhoeae, and Treponema pallidum are responsible for various sexually transmitted infections.

Question 11

Name some bacteria responsible for skin and wound infections.

Answer 11

Examples include Bacillus anthracis (cutaneous anthrax), Borrelia burgdorferi (Lyme disease), Clostridium tetani (tetanus), and Staphylococcus aureus.

Question 12

Which bacteria cause eye infections?

Answer 12

Chlamydia trachomatis and Haemophilus aegyptius are associated with eye infections.

Question 13

What are zoonotic infections, and which bacteria are involved?

Answer 13

Zoonotic infections can be transmitted from animals to humans. Examples include Bacillus anthracis, Brucella abortus, Borrelia burgdorferi, Listeria monocytogenes, Rickettsia rickettsii, Rickettsia prowazekii, and Yersinia pestis.

Question 14

What bacteria are commonly associated with health care–associated infections?

Answer 14

Health care-associated infections can be caused by Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis.

Question 15

What factors determine the survival and growth of bacteria within the human body?

Answer 15

Bacterial survival and growth depend on the effectiveness of the body’s defense mechanisms and the bacterium’s ability to resist these defenses.

Question 16

What is bacterial pathogenesis, and why is it significant in understanding diseases?

Answer 16

Bacterial pathogenesis is the process by which bacteria cause diseases. Understanding it is crucial for combatting bacterial infections.

Question 17

Can you provide an example of a bacterium that has evolved into a life-threatening pathogen?

Answer 17

Staphylococcus aureus is an example of a bacterium that has adapted to become a dangerous pathogen.

Question 18

What is the role of Staphylococcus aureus in healthcare-associated infections?

Answer 18

Staphylococcus aureus is a major cause of hospital-acquired infections.

Question 19

How is Staphylococcus aureus spreading beyond healthcare settings?

Answer 19

S. aureus is increasingly spreading within communities outside of healthcare facilities.

Question 20

Where is Staphylococcus aureus commonly found in the human body?

Answer 20

S. aureus is a common commensal inhabitant of normal skin and nasal passages.

Question 21

What percentage of individuals may carry Staphylococcus aureus in their nasal passages?

Answer 21

Estimates indicate that 30% to 80% of individuals may carry S. aureus in their noses.

Question 22

How does Staphylococcus aureus typically transmit from person to person?

Answer 22

The main method of transmission for S. aureus is through direct skin-to-skin contact or contact with shared items or surfaces used by contaminated individuals, such as towels and bandages.

Question 23

What type of pathogen is Staphylococcus aureus, and when does it become life-threatening?

Answer 23

S. aureus is an opportunistic pathogen, and it becomes life-threatening when the opportunity arises.

Question 24

Where do skin infections commonly occur due to S. aureus?

Answer 24

Skin infections caused by S. aureus often occur at sites of trauma, such as cuts, abrasions, and areas covered by hair.

Question 25

How do most S. aureus infections initially manifest on the skin?

Answer 25

Most S. aureus infections appear as red and swollen pustules on the skin, often containing pus or other drainage.

Question 26

What are some of the more severe conditions that S. aureus skin infections can progress to?

Answer 26

S. aureus skin infections can progress to conditions like abscesses, boils, carbuncles, cellulitis, or furunculosis.

Question 27

From where can invasive diseases caused by S. aureus originate?

Answer 27

Invasive diseases caused by S. aureus can originate from wound infections, including trauma, surgical wounds, and indwelling medical devices, potentially leading to fatal septicemia and internal organ abscesses.

Question 28

What is the typical Gram stain and cluster formation of staphylococci?

Answer 28

Staphylococci are Gram-positive cocci that grow in grapelike clusters.

Question 29

What determines the severity, location, and clinical features of Staphylococcus aureus infections?

Answer 29

Staphylococcus aureus possesses various virulence factors that influence the characteristics of infections.

Question 30

Do all strains of Staphylococcus aureus express the same virulence factors?

Answer 30

No, individual strains of S. aureus may exhibit only a subset of the entire array of virulence factors.

Question 31

What are biofilms, and what microorganisms can be part of them?

Answer 31

Biofilms are complex multicellular masses of microorganisms. They can include bacteria, fungi, and viruses.

Question 32

Why is bacterial growth in biofilms advantageous for microorganisms?

Answer 32

Bacterial growth in biofilms provides protection from host responses and exposure to antibiotics, offering a survival advantage.

Question 33

Name some medical conditions associated with biofilms.

Answer 33

Biofilms are linked to otitis media, urinary tract infections from catheters, diabetic foot ulcers, infected burn wounds, vaginitis, osteomyelitis, pneumonia in cystic fibrosis, and oral diseases like dental caries and periodontitis.

Question 34

How are Staphylococcus aureus biofilms relevant in healthcare?

Answer 34

S. aureus biofilms are associated with persistent nasopharyngeal colonization and colonization of implanted medical devices.

Question 35

What role do surface proteins play in the adherence of microorganisms in biofilms and to connective tissues?

Answer 35

Surface proteins mediate adherence among microorganisms in biofilms and to connective tissues such as laminin, fibrin, fibronectin, and endothelium.

Question 36

In which medical conditions does bacterial attachment to collagen occur?

Answer 36

Strains causing osteomyelitis and septic arthritis attach to collagen.

Question 37

How do capsular polysaccharides protect bacteria and what do they attach to?

Answer 37

Capsular polysaccharides attach to prosthetic devices and protect against phagocytosis.

Question 38

What is the role of Staphylococcal protein A in binding immunoglobulin G (IgG)?

Answer 38

Staphylococcal protein A binds IgG by the Fc portion, leaving the Fab regions facing outward, preventing IgG from activating complement or acting as an opsonin.

Question 39

Which other protein binds and neutralizes IgG in Staphyylococcus?

Answer 39

Staphylococcal binder of immunoglobulin also binds and neutralizes IgG.

Question 40

How does Staphylococcus inhibit complement activity?

Answer 40

Staphylococcus produces proteins that inhibit complement activity, including the activation of C3 and C5, preventing the production of C3b, C3a, and C5a.

Question 41

What does coagulase do in the context of bacterial surface masking?

Answer 41

Coagulase induces fibrin clotting on the bacterial surface, which masks bacterial antigens under a layer of self-proteins.

Question 42

Coagulase induces fibrin clotting on the bacterial surface, which masks bacterial antigens under a layer of self-proteins.

Answer 42

Coagulase promotes blood clot formation.

Question 43

What is the function of staphylokinase in S. aureus infections?

Answer 43

Staphylokinase breaks down clots formed in the body.

Question 44

How do exfoliative toxins contribute to infections caused by S. aureus?

Answer 44

Exfoliative toxins cause the separation of the epidermis, resulting in scalded skin syndrome.

Question 45

What role does lipase play in Staphylococcus aureus infections?

Answer 45

Lipase degrades lipids on the skin surface, which helps in the formation of abscesses.

Question 46

What type of illness is caused by enterotoxins produced by S. aureus?

Answer 46

Enterotoxins are responsible for causing food poisoning.

Question 47

What is the significance of superantigens produced by S. aureus?

Answer 47

Superantigens are discussed in Chapter 7 and play a role in the pathogenicity of S. aureus.

Question 48

How do different strains of S. aureus vary in their disease-causing capabilities?

Answer 48

Each infectious strain of S. aureus may produce different combinations of toxins, leading to variations in their capacity to cause specific diseases, such as purulent dermal infections, food poisoning, or toxic shock syndrome.

Question 49

Why has antibiotic resistance become a significant problem with Staphylococcus aureus (S. aureus)?

Answer 49

Pathogenic S. aureus strains have produced β-lactamase, an enzyme that destroys penicillin, for many years.

Question 50

What is methicillin-resistant Staphylococcus aureus (MRSA), and why is it a concern?

Answer 50

MRSA is a strain of S. aureus that has developed resistance to broad-spectrum antibiotics, including methicillin-like antibiotics. It poses a significant antibiotic resistance challenge.

Question 51

Why is S. aureus considered an opportunistic pathogen?

Answer 51

S. aureus is an opportunistic pathogen due to its numerous virulence factors that neutralize components of the immune systems, damage tissue, and resist many common antibiotics.

Question 52

What potential approach can be used to combat S. aureus infections?

Answer 52

Vaccination is an option for addressing S. aureus infections.

Question 53

Why might vaccinating against S. aureus be challenging?

Answer 53

Vaccination can be difficult to implement, which can pose challenges in addressing S. aureus infections.

Question 54

What is the name of the endotoxin produced by Gram-negative microbes?

Answer 54

Gram-negative microbes produce an endotoxin called lipopolysaccharide (LPS).

Question 55

How can the release of LPS occur from these bacteria?

Answer 55

The release of LPS can happen due to bacterial growth, lysis, destruction, or antibiotic treatment.

Question 56

Can antibiotics prevent the toxic effects of endotoxins?

Answer 56

No, antibiotics cannot prevent the toxic effects of endotoxins.

Question 57

Why are bacteria that produce endotoxins referred to as pyrogenic bacteria?

Answer 57

They are called pyrogenic bacteria because they activate the inflammatory process and induce fever.

Question 58

What part of lipopolysaccharide (LPS) is responsible for its toxic effects?

Answer 58

The innermost part of LPS, known as lipid A, consists of polysaccharide and fatty acids and is responsible for the toxic effects of the substance.

Question 59

What is bacteremia?

Answer 59

Bacteremia occurs when bacteria are present in the bloodstream.

Question 60

What characterizes Gram-negative sepsis (sepsis or septicemia)?

Answer 60

Gram-negative sepsis occurs when bacteria are growing in the blood and release significant amounts of endotoxin.

Question 61

What can endotoxin release in Gram-negative sepsis lead to, and what is the associated mortality rate?

Answer 61

Endotoxin release can lead to endotoxic shock with a mortality rate of up to 50%.

Question 62

How does endotoxin affect the immune response in sepsis?

Answer 62

Released endotoxin and other bacterial products interact with pattern recognition receptors (PRRs) and induce the excessive production of proinflammatory cytokines, including TNF-α, IL-1, and IL-6.

Question 63

What systems are activated by endotoxin in Gram-negative sepsis, and what are their consequences?

Answer 63

Endotoxin activates the complement and clotting systems, leading to increased capillary permeability, which allows plasma to escape into surrounding tissues, contributing to hypotension and, in severe cases, cardiovascular shock.

Question 64

What syndrome can result from the activation of the coagulation cascade in sepsis?

Answer 64

Activation of the coagulation cascade can lead to the syndrome of disseminated intravascular coagulation (DIC).