INFECTIONS - M - W3 - basics of antibiotics

Question 1

What is Penicillin?

Answer 1

Penicillin is an antibiotic that belongs to the beta-lactam class of drugs. It is used to kill bacteria by targeting their cell wall.

Penicillin was the first true antibiotic discovered and is widely used in medicine.

Question 2

How does Penicillin work?

Answer 2

Penicillin blocks penicillin-binding proteins (PBPs), preventing bacteria from building a proper cell wall. Without a strong wall, bacteria burst and die.

This process is referred to as bactericidal action.

Question 3

What is Beta-Lactamase?

Answer 3

Beta-lactamase is an enzyme that destroys penicillin and other beta-lactam antibiotics before they can work.

It acts as scissors that cut penicillin, rendering it ineffective.

Question 4

How do some bacteria become resistant to Penicillin?

Answer 4

Bacteria that produce beta-lactamase can defend themselves against penicillin.

This resistance mechanism allows these bacteria to survive in the presence of penicillin.

Question 5

How can we overcome Beta-Lactamase?

Answer 5

We can use:
* Beta-lactamase inhibitors
* Stronger beta-lactam antibiotics
* Non-beta-lactam antibiotics

Each of these strategies helps to combat bacterial resistance.

Question 6

What is an example of combining an antibiotic with a beta-lactamase inhibitor?

Answer 6

Amoxicillin + Clavulanic Acid (Augmentin)

Clavulanic acid blocks beta-lactamase, allowing amoxicillin to work effectively.

Question 7

What are some examples of stronger beta-lactam antibiotics?

Answer 7

Some examples include:
* Cephalosporins (like ceftriaxone)
* Carbapenems (like meropenem)

These antibiotics are designed to resist beta-lactamase.

Question 8

What are non-beta-lactam antibiotics that can be used against resistant bacteria?

Answer 8

Examples include:
* Macrolides (like azithromycin)
* Fluoroquinolones (like levofloxacin)

These alternatives are utilized when bacteria produce strong beta-lactamases.

Question 9

What specific bacteria is known for producing a lot of beta-lactamase?

Answer 9

Klebsiella pneumoniae

This bacterium’s production of beta-lactamase makes normal penicillins ineffective.

Question 10

What type of antibiotics are used for Klebsiella pneumoniae due to its beta-lactamase production?

Answer 10

Carbapenems (like meropenem)

Carbapenems are designed to resist the effects of beta-lactamase.

Question 11

What type of bacteria is penicillin more effective against?

Answer 11

Gram-Positive bacteria

Examples include Streptococcus and Staphylococcus.

Question 12

Why is penicillin less effective against Gram-Negative bacteria?

Answer 12

Because of their outer membrane

The outer membrane blocks penicillin from entering.

Question 13

What structural feature do Gram-Positive bacteria have that allows penicillin to be effective?

Answer 13

Thick peptidoglycan layer

Gram-Positive bacteria lack an outer membrane.

Question 14

What are examples of Gram-Negative bacteria?

Answer 14

• E. coli
• Klebsiella
• Pseudomonas

These bacteria have an outer membrane that increases resistance to penicillin.

Question 15

What is a solution for treating Gram-Negative bacteria?

Answer 15

• Use broad-spectrum penicillins (e.g., amoxicillin, piperacillin)
• Use beta-lactamase inhibitors (e.g., clavulanic acid, tazobactam)
• Use stronger beta-lactams like cephalosporins or carbapenems

Broad-spectrum penicillins and beta-lactamase inhibitors help overcome resistance.

Question 16

What does ESBL stand for?

Answer 16

Extended-Spectrum Beta-Lactamase

ESBL is an enzyme produced by certain Gram-negative bacteria that can break down a wide range of beta-lactam antibiotics.

Question 17

Which types of bacteria commonly produce ESBL?

Answer 17

Klebsiella pneumoniae and E. coli

These are among the Gram-negative bacteria that can produce Extended-Spectrum Beta-Lactamases.

Question 18

How do ESBL enzymes differ from regular beta-lactamase?

Answer 18

ESBL enzymes can destroy stronger antibiotics, including:
* Penicillins (e.g., amoxicillin, penicillin G)
* Most cephalosporins (e.g., ceftriaxone, cefotaxime, ceftazidime)
* Monobactams (e.g., aztreonam)

Regular beta-lactamase primarily targets penicillins.

Question 19

What is the first-line treatment for ESBL infections?

Answer 19

Carbapenems

Examples include Meropenem, Imipenem, and Ertapenem, which are resistant to ESBL enzymes.

Question 20

List two non-beta-lactam alternatives for treating ESBL infections.

Answer 20

1. Fluoroquinolones (e.g., Levofloxacin, Ciprofloxacin)
2. Aminoglycosides (e.g., Gentamicin, Amikacin)

These options are considered when carbapenems cannot be used.

Question 21

What newer options are available for multi-drug resistant ESBL bacteria?

Answer 21

1. Ceftazidime-Avibactam
2. Fosfomycin

Ceftazidime-Avibactam combines a cephalosporin with a beta-lactamase inhibitor, while Fosfomycin is used for UTIs caused by ESBL bacteria.

Question 22

True or False: ESBL bacteria are resistant to most beta-lactams.

Answer 22

True

This resistance limits treatment options significantly.

Question 23

What are the major concerns associated with ESBL bacteria?

Answer 23

1. Resistant to many antibiotics
2. Can spread easily in hospitals
3. Can lead to severe infections

These infections can include pneumonia, bloodstream infections (sepsis), and UTIs.

Question 24

Fill in the blank: The best treatment for ESBL infections is _______.

Answer 24

Carbapenems

Specifically, Meropenem is often cited as the best option.

Question 25

What types of infections can ESBL bacteria lead to?

Answer 25

1. Pneumonia 2. Bloodstream infections (sepsis) 3. UTIs ## Footnote These infections can be severe and difficult to treat due to antibiotic resistance.

Question 26

Do beta-lactam antibiotics work only for Gram-positive bacteria?

Answer 26

No! Beta-lactam antibiotics can work against both Gram-positive and Gram-negative bacteria, but with some limitations.

Question 27

Why do beta-lactams work well on Gram-positive bacteria?

Answer 27

Gram-positive bacteria have a thick peptidoglycan layer but no outer membrane. Beta-lactam antibiotics directly attack the peptidoglycan, weakening the cell wall and causing the bacteria to burst.

Question 28

What is the characteristic of Gram-negative bacteria that affects beta-lactam efficacy?

Answer 28

Gram-negative bacteria have an extra outer membrane that makes them harder to kill, acting as a shield that prevents many beta-lactam antibiotics from reaching the peptidoglycan layer.

Question 29

How can we get around the challenge of beta-lactams working on Gram-negative bacteria?

Answer 29

Broad-spectrum beta-lactams can still enter Gram-negative bacteria, such as Ampicillin, Amoxicillin (with beta-lactamase inhibitors), Cephalosporins (3rd & 4th gen), and Carbapenems.

Question 30

What are beta-lactamase inhibitors?

Answer 30

Beta-lactamase inhibitors are compounds that protect beta-lactam antibiotics from being destroyed by beta-lactamase enzymes produced by Gram-negative bacteria.

Question 31

What is an example of a combination of a beta-lactam antibiotic and a beta-lactamase inhibitor?

Answer 31

Amoxicillin + Clavulanic Acid (Augmentin) works against some Gram-negative bacteria.

Question 32

Which beta-lactam class is effective against Gram-negative bacteria?

Answer 32

Some beta-lactam classes effective against Gram-negative bacteria include: * Aminopenicillins (e.g., Amoxicillin, Ampicillin) * Cephalosporins (3rd & 4th gen, e.g., ceftriaxone, cefepime) * Carbapenems (e.g., meropenem)

Question 33

True or False: Basic Penicillin (Penicillin G) works for Gram-negative bacteria.

Answer 33

False.

Question 34

Fill in the blank: Modified beta-lactams like _______ and _______ can work against Gram-negative bacteria too.

Answer 34

[cephalosporins, carbapenems]

Question 35

What are the beta-lactam classes and their effectiveness against Gram-positive and Gram-negative bacteria?

Answer 35

| Beta-Lactam Class | Gram-Positive? | Gram-Negative? | Example | | --- | --- | --- | --- | | Penicillins | ✔️ Yes | ❌ No (unless modified) | Penicillin G | | Aminopenicillins | ✔️ Yes | ⚠️ Some | Amoxicillin, Ampicillin | | Penicillin + Beta-Lactamase Inhibitor | ✔️ Yes | ✔️ Yes | Augmentin (Amoxicillin + Clavulanic Acid) | | Cephalosporins (3rd & 4th Gen) | ✔️ Yes | ✔️ Yes | Ceftriaxone, Cefepime | | Carbapenems | ✔️ Yes | ✔️ Yes (very strong) | Meropenem |

Question 36

What is α-Hemolysis?

Answer 36

Partial lysis of red blood cells with greenish discoloration around colonies ## Footnote Example organisms include Streptococcus pneumoniae and the viridans group streptococci.

Question 37

What color change indicates β-Hemolysis?

Answer 37

Clear zone around colonies due to complete lysis of red blood cells ## Footnote Example organisms include Streptococcus pyogenes and Streptococcus agalactiae.

Question 38

What is γ-Hemolysis?

Answer 38

No lysis of red blood cells with no change in appearance of the blood agar around the colony ## Footnote Often referred to as non-hemolytic bacteria.

Question 39

Define gamma-hemolytic bacteria.

Answer 39

Organisms that do not break down red blood cells at all ## Footnote They do not produce significant hemolysins.

Question 40

Name a common γ-Hemolytic bacteria.

Answer 40

Enterococcus species ## Footnote Examples include Enterococcus faecalis and Enterococcus faecium.

Question 41

What infections can Enterococcus species cause?

Answer 41

Urinary tract infections, endocarditis, and sometimes sepsis ## Footnote Particularly in immunocompromised patients.

Question 42

What is a characteristic of Streptococcus bovis?

Answer 42

Found in the gastrointestinal tract and associated with infections like endocarditis ## Footnote It shows γ-hemolysis on blood agar.

Question 43

True or False: β-Hemolytic bacteria cause partial lysis of red blood cells.

Answer 43

False ## Footnote β-Hemolytic bacteria cause complete lysis.

Question 44

Fill in the blank: The term 'gamma-hemolytic' refers to organisms that do not break down _______.

Answer 44

red blood cells

Question 45

What type of bacteria are Enterococci known for?

Answer 45

γ-hemolytic ## Footnote Enterococci are a type of bacteria that can cause infections and are often resistant to multiple antibiotics.

Question 46

What antibiotics are Enterococci resistant to?

Answer 46

Penicillin and vancomycin ## Footnote This resistance makes infections caused by Enterococci challenging to treat.

Question 47

Are Streptococcus species generally susceptible or resistant to antibiotics?

Answer 47

Generally susceptible ## Footnote Most Streptococcus species respond well to antibiotic treatment.

Question 48

What specific type of Streptococcus can be resistant to certain drugs?

Answer 48

Viridans streptococci ## Footnote Resistance may occur especially in individuals with predisposing factors.

Question 49

What predisposing factor can lead to resistance in viridans streptococci?

Answer 49

Heart valve disease ## Footnote This condition can increase the likelihood of viridans streptococci being resistant to antibiotics. ---- explore the why!!!!!

Question 50

What type of hemolysis do α-hemolytic bacteria produce?

Answer 50

Partial hemolysis of red blood cells ## Footnote This results in a greenish discoloration around the colonies on blood agar due to the reduction of hemoglobin to methemoglobin.

Question 51

What pathogen is associated with pneumonia, meningitis, and otitis media?

Answer 51

Streptococcus pneumoniae

Question 52

Which group of streptococci can inhabit the mouth and throat but may cause endocarditis?

Answer 52

Viridans group streptococci ## Footnote Includes species like Streptococcus mitis and Streptococcus sanguinis.

Question 53

What type of hemolysis do β-hemolytic bacteria produce?

Answer 53

Complete lysis of red blood cells ## Footnote This results in a clear zone around the colony on blood agar due to the full breakdown of hemoglobin.

Question 54

What infections are caused by Streptococcus pyogenes?

Answer 54

* Strep throat * Scarlet fever * Rheumatic fever * Necrotizing fasciitis ## Footnote Scarlet fever can cause rheumatic fever if left untreated. Both occur due to the same bacteria that causes strep throat. Rheumatic fever is generally more serious and affects several organs in the body, including the heart. Left untreated, it can lead to permanent heart damage and may be fatal Rheumatic fever is an inflammatory disease that can develop when strep throat or scarlet fever isn't properly treated. Strep throat and scarlet fever are caused by an infection with streptococcus (strep-toe-KOK-us) bacteria. Rheumatic fever most often affects children ages 5 to 15 Necrotising fasciitis is an infection that can happen after getting a wound. It causes damage to the deep layers of your skin. The infection may get into the body through: cuts and scratches. burns and scalds.

Question 55

What is the primary infection caused by Streptococcus agalactiae?

Answer 55

Neonatal infections, including sepsis and meningitis

Question 56

What type of infections can Enterococcus faecalis cause?

Answer 56

* Urinary tract infections * Endocarditis

Question 57

What types of infections is Staphylococcus aureus commonly associated with?

Answer 57

* Skin abscesses * Pneumonia * Food poisoning

Question 58

Examples of a-hemolytic bacteria

Answer 58

Strep pneumoniae Viridans group strep

Question 59

Examples of b hemolytic bacteria

Answer 59

Strep pyogenes Strep agalactiae Enterococcus faecalis Staph aureus

Question 60

Summary of a,b,g hemolysis

Answer 60

α-hemolytic: Partial lysis, greenish zone (e.g., S. pneumoniae, viridans streptococci). β-hemolytic: Complete lysis, clear zone (e.g., S. pyogenes, S. agalactiae). γ-hemolytic: No lysis, no change in the agar (e.g., Enterococcus faecalis, S. bovis).

Question 61

beta lactam classes

Answer 61

True beta lactam anaphylaxis is <0.05 % Penicillin Flucloxacillin Amoxicillin Cephalosporins Piperacillin/tazobactam carbepenems

Question 63

What is Clostridioides difficile?

Answer 63

A Gram-positive, anaerobic, spore-forming bacillus that causes antibiotic-associated diarrhea and pseudomembranous colitis.

Question 64

What type of staining does Clostridioides difficile exhibit?

Answer 64

Stains purple in Gram staining due to its thick peptidoglycan layer.

Question 65

What environment does Clostridioides difficile require for growth?

Answer 65

Low-oxygen environments, such as the colon.

Question 66

What are the key features of Clostridioides difficile?

Answer 66

* Gram-Positive Bacillus * Anaerobic * Spore-Forming * Toxin-Producing

Question 67

What is the function of Toxin A produced by Clostridioides difficile?

Answer 67

Causes fluid secretion, leading to diarrhea.

Question 68

What is the function of Toxin B produced by Clostridioides difficile?

Answer 68

Causes colonic inflammation and cell death, leading to pseudomembranous colitis.

Question 69

What are the 4Cs that contribute to the risk of C. difficile infection?

Answer 69

* Clindamycin * Cephalosporins * Ciprofloxacin * Co-amoxiclav ## Footnote MNEMONIC WITH GERMAN PRONUNCIATION L E I O

Question 70

What is the primary mechanism by which C. difficile causes disease?

Answer 70

Disruption of gut flora due to broad-spectrum antibiotics.

Question 71

What are the symptoms of mild to moderate C. difficile infection?

Answer 71

* Watery diarrhea (≥3 loose stools in 24 hours) * Abdominal pain & cramping * Low-grade fever

Question 72

What are the symptoms of severe C. difficile infection (pseudomembranous colitis)?

Answer 72

* Profuse diarrhea * Severe abdominal pain * High fever (>38.5°C) * Leukocytosis * Dehydration & electrolyte imbalances * Pseudomembranous plaques on the colon

Question 73

What life-threatening complications can arise from C. difficile infection?

Answer 73

* Toxic megacolon * Sepsis & shock

Question 74

What are the primary diagnostic tests for C. difficile infection?

Answer 74

* Toxin A/B ELISA * PCR (NAAT Test) * GDH Test * Colonoscopy (if severe)

Question 75

What is the first-line treatment for mild to moderate C. difficile infection?

Answer 75

Oral Vancomycin (125 mg QID for 10 days) or Oral Fidaxomicin.

Question 76

What should be avoided in the primary treatment of C. difficile infection?

Answer 76

Metronidazole (only used if others are unavailable).

Question 77

What is the treatment for severe C. difficile infection?

Answer 77

Oral Vancomycin + IV Metronidazole.

Question 78

What critical prevention measure is recommended for C. difficile infection?

Answer 78

Handwashing with soap & water (alcohol does NOT kill spores).

Question 79

Fill in the blank: C. difficile produces _______ leading to pseudomembranous colitis.

Answer 79

Toxin A & B

Question 80

True or False: Clostridioides difficile is resistant to heat and alcohol-based disinfectants.

Answer 80

True

Question 81

What are common risk factors for C. difficile infection?

Answer 81

* Antibiotic use (especially the 4Cs) * Hospitalization or nursing home stay * Immunosuppression * Elderly patients (>65 years old) * Prolonged PPI use * Recent GI surgery or tube feeding

Question 82

How do the 4Cs antibiotics affect gut microbiota?

Answer 82

They disrupt the normal gut microbiota, allowing C. difficile to overgrow. ## Footnote This disruption can lead to antibiotic-associated diarrhea or severe complications like pseudomembranous colitis.

Question 83

What are some examples of cephalosporins that can lead to C. difficile overgrowth?

Answer 83

Ceftriaxone, Cefuroxime ## Footnote These have broad-spectrum activity and can increase resistance in Streptococcus pneumoniae.

Question 84

How does co-amoxiclav increase the risk of C. difficile?

Answer 84

It has broad-spectrum activity that disrupts normal gut flora. ## Footnote This disruption can lead to the overgrowth of C. difficile.

Question 85

What opportunity do C. difficile spores have when the gut microbiota is disturbed?

Answer 85

They can germinate and cause severe colitis. ## Footnote C. difficile spores are resistant to antibiotics.

Question 86

What is the relationship between cephalosporins and Streptococcus pneumoniae?

Answer 86

Overuse has led to resistance in S. pneumoniae. ## Footnote Cephalosporins are often used to treat pneumococcal pneumonia.

Question 87

What are the circumstances for using doxycycline in pneumonia?

Answer 87

1. Community-Acquired Pneumonia (CAP) in Mild Cases 2. In Patients with Penicillin Allergy 3. In Cases of Suspected Atypical Pneumonia 4. In Patients with COPD Exacerbations and Pneumonia ## Footnote Doxycycline is an alternative to other antibiotics in these scenarios.

Question 88

What atypical pneumonia pathogens does doxycycline effectively target?

Answer 88

Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila ## Footnote Doxycycline also covers some strains of Streptococcus pneumoniae.

Question 89

When can doxycycline be used as an alternative for penicillin-allergic patients?

Answer 89

For treating mild pneumococcal pneumonia. ## Footnote It serves as a substitute for beta-lactam antibiotics.

Question 90

What is the role of doxycycline in treating COPD patients with pneumonia?

Answer 90

It is used to treat bacterial infections complicating COPD. ## Footnote Especially if Haemophilus influenzae, Moraxella catarrhalis, or S. pneumoniae are suspected.

Question 91

True or False: Doxycycline is commonly used for atypical pneumonia.

Answer 91

True ## Footnote It is an alternative to macrolides and fluoroquinolones.

Question 92

What are the risks associated with the overuse of broad-spectrum antibiotics?

Answer 92

They may select for drug-resistant pneumococci. ## Footnote This makes treatment more difficult.

Question 93

Fill in the blank: The 4Cs antibiotics increase the risk of _______ and contribute to antibiotic resistance.

Answer 93

C. difficile infection ## Footnote They also contribute to resistance in S. pneumoniae.

Question 94

What is a broad-spectrum antibiotic?

Answer 94

An antibiotic that is effective against a wide range of bacteria, including both Gram-positive and Gram-negative organisms. ## Footnote Broad-spectrum antibiotics target multiple bacterial species rather than being specific to one type.

Question 95

Which types of bacteria do broad-spectrum antibiotics target?

Answer 95

Both Gram-positive and Gram-negative organisms. ## Footnote This allows for the treatment of various bacterial infections.

Question 96

What is the primary mechanism by which broad-spectrum antibiotics work?

Answer 96

By inhibiting essential bacterial processes. ## Footnote These processes include cell wall synthesis, protein synthesis, and DNA/RNA synthesis.

Question 97

What is an example of a broad-spectrum antibiotic that inhibits cell wall synthesis?

Answer 97

Carbapenems, Amoxicillin-Clavulanate. ## Footnote These antibiotics disrupt the structural integrity of bacterial cell walls.

Question 98

What is an example of a broad-spectrum antibiotic that inhibits protein synthesis?

Answer 98

Tetracyclines, Chloramphenicol. ## Footnote These antibiotics interfere with the bacteria's ability to produce proteins necessary for growth.

Question 99

What is an example of a broad-spectrum antibiotic that inhibits DNA/RNA synthesis?

Answer 99

Fluoroquinolones, Rifampin. ## Footnote These antibiotics prevent bacteria from replicating their genetic material.

Question 100

True or False: Broad-spectrum antibiotics are specific to one type of bacteria.

Answer 100

False. ## Footnote They are designed to target a wide variety of bacterial species.

Question 101

What are examples of Beta-Lactams?

Answer 101

Amoxicillin-Clavulanate, Piperacillin-Tazobactam, Carbapenems ## Footnote Beta-Lactams are a class of antibiotics that inhibit cell wall synthesis.

Question 102

What is the mechanism of action for Tetracyclines?

Answer 102

Inhibits protein synthesis (30S ribosome) ## Footnote Tetracyclines are effective against Gram (+), Gram (-), and Atypicals.

Question 103

Which types of bacteria do Macrolides target?

Answer 103

Gram (+), Some Gram (-), Atypicals ## Footnote Macrolides inhibit protein synthesis at the 50S ribosome. e.g. Azithromycin

Question 104

What is the mechanism of action for Fluoroquinolones?

Answer 104

Inhibits DNA synthesis (DNA gyrase) ## Footnote Fluoroquinolones are effective against Gram (-), Some Gram (+), and Atypicals.

Question 105

What does Chloramphenicol inhibit?

Answer 105

Inhibits protein synthesis (50S) ## Footnote Chloramphenicol has a broad spectrum, including anaerobes.

Question 106

Fill in the blank: Tetracyclines are effective against _______.

Answer 106

[Gram (+), Gram (-), Atypicals]

Question 107

True or False: Fluoroquinolones are effective against Gram (+) bacteria.

Answer 107

True ## Footnote Fluoroquinolones target some Gram (+) bacteria.

Question 108

What is the primary target of Beta-Lactams?

Answer 108

Cell wall synthesis ## Footnote Beta-Lactams are used to treat a variety of bacterial infections.

Question 109

List examples of Macrolides.

Answer 109

* Azithromycin * Clarithromycin ## Footnote Macrolides are known for inhibiting protein synthesis.

Question 110

What is the unique mechanism of action of Chloramphenicol?

Answer 110

Inhibits protein synthesis at the 50S ribosome ## Footnote This antibiotic is broad-spectrum and can affect anaerobic bacteria.

Question 111

What class of antibiotics does Methicillin belong to?

Answer 111

Beta-lactam antibiotics ## Footnote Methicillin is specifically within the Penicillin subclass.

Question 112

What is the subclass of Methicillin?

Answer 112

Penicillins ## Footnote Methicillin is categorized as a Penicillinase-Resistant Penicillin.

Question 113

What group does Methicillin belong to?

Answer 113

Penicillinase-Resistant Penicillins (Anti-Staphylococcal Penicillins) ## Footnote This group is specifically designed to combat penicillin-resistant bacteria.

Question 114

Why was Methicillin developed?

Answer 114

To resist beta-lactamase (penicillinase) produced by Staphylococcus aureus ## Footnote This enzyme destroys regular penicillins like penicillin G.

Question 115

What gene is associated with Methicillin-Resistant Staphylococcus aureus (MRSA)?

Answer 115

mecA gene ## Footnote This gene encodes altered penicillin-binding proteins (PBPs) that do not bind methicillin.

Question 116

Name three other Penicillinase-Resistant Penicillins similar to Methicillin.

Answer 116

* Oxacillin * Nafcillin * Dicloxacillin ## Footnote These alternatives are used clinically instead of Methicillin.

Question 117

Why was Methicillin withdrawn from clinical use?

Answer 117

Due to toxicity (interstitial nephritis) ## Footnote The nephrotoxic effects led to its replacement by other penicillinase-resistant penicillins.

Question 118

What is the mechanism of action of Methicillin?

Answer 118

Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs) ## Footnote This prevents peptidoglycan cross-linking, leading to bacterial cell lysis.

Question 119

Is Methicillin still used in clinical practice?

Answer 119

No ## Footnote It has been replaced by oxacillin and nafcillin due to nephrotoxicity.

Question 120

What does MRSA stand for?

Answer 120

Methicillin-Resistant Staphylococcus aureus ## Footnote MRSA is resistant to all beta-lactams due to the mecA gene.

Question 121

Fill in the blank: Methicillin is a _______ antibiotic.

Answer 121

beta-lactam ## Footnote It is specifically a penicillinase-resistant penicillin.

Question 122

What does MRSA stand for?

Answer 122

Methicillin-Resistant Staphylococcus aureus

Question 123

What type of bacterium is MRSA?

Answer 123

Gram-positive

Question 124

What is the mecA gene responsible for in MRSA?

Answer 124

Encodes an altered penicillin-binding protein (PBP2a)

Question 125

What antibiotics is MRSA resistant to?

Answer 125

All beta-lactam antibiotics including penicillins, cephalosporins, and carbapenems

Question 126

What are the two major types of MRSA?

Answer 126

* Hospital-Acquired MRSA (HA-MRSA) * Community-Acquired MRSA (CA-MRSA)

Question 127

Where is Hospital-Acquired MRSA commonly acquired?

Answer 127

Hospitals, nursing homes, ICUs

Question 128

Who is commonly affected by Hospital-Acquired MRSA?

Answer 128

* Elderly * Immunocompromised * Post-surgical patients * Ventilated patients

Question 129

What type of infections are typically caused by HA-MRSA?

Answer 129

* Pneumonia * Bloodstream infections (sepsis) * Surgical site infections * Catheter infections

Question 130

Where is Community-Acquired MRSA typically acquired?

Answer 130

Outside healthcare settings

Question 131

Who is commonly affected by Community-Acquired MRSA?

Answer 131

* Young, healthy individuals * Athletes * Unhoused individuals * Prisoners * Military

Question 132

What type of infections are typically caused by CA-MRSA?

Answer 132

* Skin infections (boils, abscesses) * Necrotizing pneumonia * Osteomyelitis

Question 133

What is the primary reason for MRSA's resistance to beta-lactam antibiotics?

Answer 133

Production of an altered Penicillin-Binding Protein (PBP2a)

Question 134

Which first-line antibiotic is used for severe MRSA infections?

Answer 134

Vancomycin

Question 135

What route is Vancomycin administered?

Answer 135

IV

Question 136

What is Daptomycin used for in MRSA treatment?

Answer 136

MRSA bacteremia, right-sided endocarditis

Question 137

Which antibiotic is the only beta-lactam that covers MRSA?

Answer 137

Ceftaroline

Question 138

What is the risk associated with Clindamycin use?

Answer 138

High risk of C. difficile infection

Question 139

What should be suspected in hospitalized patients with pneumonia or sepsis?

Answer 139

MRSA

Question 140

What infection control measures are used to prevent MRSA spread?

Answer 140

* Hand hygiene * Contact isolation * Screening & Decolonization

Question 141

What is the gold standard for treating severe MRSA infections?

Answer 141

Vancomycin (IV)

Question 142

What are the non-beta-lactam antibiotics for mild/moderate MRSA infections?

Answer 142

* Linezolid * TMP-SMX * Doxycycline

Question 143

Fill in the blank: CA-MRSA is usually resistant to beta-lactams but more susceptible to _______.

Answer 143

non-beta-lactams

Question 144

True or False: Linezolid is the only oral option for severe MRSA infections.

Answer 144

True

Question 145

What types of bacteria do broad-spectrum antibiotics target?

Answer 145

Many types (Gram +, Gram -, atypicals) ## Footnote Broad-spectrum antibiotics are effective against a wide range of bacteria, making them versatile in treatment.

Question 146

What types of bacteria do narrow-spectrum antibiotics target?

Answer 146

Specific bacteria ## Footnote Narrow-spectrum antibiotics are designed to target a specific group of bacteria.

Question 147

How do broad-spectrum antibiotics affect the microbiome?

Answer 147

High disruption (kills good & bad bacteria) ## Footnote This disruption can lead to a variety of health issues due to the loss of beneficial bacteria.

Question 148

How do narrow-spectrum antibiotics affect the microbiome?

Answer 148

Minimal disruption ## Footnote They tend to preserve the normal microbiota while targeting specific pathogens.

Question 149

What is the risk of antibiotic resistance associated with broad-spectrum antibiotics?

Answer 149

Higher (due to overuse) ## Footnote The widespread use of broad-spectrum antibiotics can lead to the development of resistant bacteria.

Question 150

What is the risk of antibiotic resistance associated with narrow-spectrum antibiotics?

Answer 150

Lower ## Footnote Narrow-spectrum antibiotics are less likely to contribute to the development of resistance.

Question 151

Give an example of a broad-spectrum antibiotic.

Answer 151

Amoxicillin-clavulanate, Tetracycline, Fluoroquinolones ## Footnote These antibiotics are commonly used to treat various infections due to their broad coverage.

Question 152

Give an example of a narrow-spectrum antibiotic.

Answer 152

Penicillin G (only Gram+), Vancomycin (Gram+ only) ## Footnote These antibiotics are effective against specific bacterial types.

Question 153

What is a key advantage of broad-spectrum antibiotics in empiric therapy?

Answer 153

Useful in Empiric Therapy → When the specific pathogen is unknown ## Footnote They provide a wide coverage while waiting for specific culture results.

Question 154

What is a benefit of broad-spectrum antibiotics for polymicrobial infections?

Answer 154

Effective for Polymicrobial Infections → Mixed bacterial infections (e.g., intra-abdominal, aspiration pneumonia) ## Footnote They are capable of treating infections caused by multiple types of bacteria.

Question 155

What atypical pathogens can broad-spectrum antibiotics treat?

Answer 155

Legionella, Mycoplasma, Chlamydia ## Footnote These pathogens may not be covered by narrow-spectrum antibiotics.

Question 156

What is a disadvantage of broad-spectrum antibiotics regarding normal microbiota?

Answer 156

Disrupts Normal Microbiota → Kills beneficial bacteria, increasing risk of: * Clostridioides difficile infection (CDI) * Opportunistic infections (e.g., Candida overgrowth) ## Footnote The disruption can lead to serious complications.

Question 157

What is a consequence of the higher risk of antibiotic resistance from broad-spectrum antibiotics?

Answer 157

Promotes multi-drug resistant (MDR) bacteria like MRSA, ESBL, Pseudomonas ## Footnote The overuse of these antibiotics can lead to difficult-to-treat infections.

Question 158

What can unnecessary use of broad-spectrum antibiotics lead to?

Answer 158

Side effects → E.g., GI upset, allergic reactions, kidney/liver toxicity ## Footnote These side effects can complicate patient care and lead to additional health problems.

Question 159

Staph aureus is a Gram x

Answer 159

positive

Question 160

Pseudomona Aeruginosa is a Gram x

Answer 160

Negative

Question 161

antibiotic for staph aureus

Answer 161

oral fluclox --> see CF -

Question 162

antibiotic for pseudomonas

Answer 162

oral azithromycin --> see CF

Question 163

Pseumonas Aeriginosa

Answer 163

Gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium ## Footnote treat with Gentamycin --- aminoglycoside ++++ see Bronchiectasis