TI- 6 Clinical uses of antibiotics

Question 1

What are the typical presentations of a lower respiratory tract infection (LRTI)?

Answer 1

Acute illness (≤21 days) with cough and ≥1 of the following: fever, sputum production, breathlessness, wheeze, chest pain.
No alternative explanation like sinusitis or asthma.

Question 2

What are the common causes of community-acquired pneumonia (CAP)?

Answer 2

Gram-positive bacteria: Streptococcus pneumoniae, Staphylococcus aureus.
Gram-negative bacteria: Klebsiella pneumoniae, Haemophilus influenzae.
Atypicals: Legionella pneumophila, Mycoplasma pneumoniae, Chlamydia pneumoniae.

Question 3

How does hospital-acquired pneumonia (HAP) differ from community-acquired pneumonia (CAP)?

Answer 3

HAP occurs ≥48 hours after hospital admission and involves more resistant pathogens, such as MRSA, multi-drug resistant Pseudomonas aeruginosa, ESBLs, and a wider range of bacteria.

Question 4

What does the CRB-65 score assess in patients with community-acquired pneumonia?

Answer 4

Confusion (disorientation or mental test score ≤8)
Respiratory rate ≥30 breaths per minute
Blood pressure: diastolic ≤60 mmHg or systolic ≤90 mmHg
Age ≥65 years

Question 5

What are some atypical signs of pneumonia?

Answer 5

Dry cough, no fever, headache, confusion, diarrhea, hyponatremia (seen in Legionella pneumonia).
Upper respiratory involvement, skin changes, encephalitis, uveitis, myocarditis, hemolytic anemia (seen in Mycoplasma pneumonia).

Question 6

Why is it important to look up current antibiotic guidance in treating pneumonia?

Answer 6

Antibiotic recommendations should be up-to-date and aligned with local epidemiology, ensuring the selected antibiotic is effective against likely pathogens and causes the least harm.

Question 7

what are the key antibiotics recommended for low-severity community-acquired pneumonia (CAP) based on NICE guidance?

Answer 7

Amoxicillin: covers Streptococcus pneumoniae with low adverse effects and resistance.
Doxycycline, clarithromycin, erythromycin: broader spectrum including Streptococcus pneumoniae.

Question 8

What are the concerns with penicillin allergies in treating infections?

Answer 8

Patients with IgE-mediated allergic reactions should avoid penicillin and related antibiotics like cephalosporins and carbapenems.
About 10% claim a penicillin allergy, but less than 1% are truly allergic. Taking an accurate history is essential.

Question 9

How does renal impairment affect antibiotic use?

Answer 9

Renal impairment increases the risk of infection, affects drug excretion, and may require dose adjustment for antibiotics like amoxicillin, ciprofloxacin, and trimethoprim.

Question 10

What are the factors to consider when choosing antibiotics for patients with hepatic impairment?

Answer 10

Hepatic impairment increases the risk of infection and affects drug metabolism, absorption, and clearance.
Some antibiotics (e.g., metronidazole) may require dose reduction.
Antibiotics like co-amoxiclav and flucloxacillin should be used with caution due to potential hepatotoxicity.

Question 11

why are oral antibiotics preferred when possible?

Answer 11

They avoid cannula-related infections, improve patient experience, are easier for outpatient use, cheaper, and support antimicrobial stewardship by reducing broad-spectrum antibiotic exposure.

Question 12

What is the significance of the “Golden hour” in sepsis treatment?

Answer 12

For each hour’s delay in administering antibiotics during septic shock, mortality increases by 7.6%.

Question 13

What is the importance of antimicrobial stewardship in using broad-spectrum antibiotics?

Answer 13

Broad-spectrum antibiotics increase the risk of selecting for resistant bacteria.
They may also harm the patient’s gut microbiota and increase the risk of opportunistic infections like Clostridium difficile.

Question 14

Why should antibiotics be administered promptly in cases of infective endocarditis

Answer 14

The endocardium is poorly vascularized, making bacterial eradication difficult.
Prompt empirical treatment is crucial, and blood cultures should be drawn before starting antibiotics.

Question 15

How does bacterial resistance impact the treatment of urinary tract infections (UTIs)?

Answer 15

Increasing resistance to antibiotics like trimethoprim and the emergence of extended-spectrum beta-lactamases (ESBL) complicates treatment.
First-line treatments like nitrofurantoin are preferred, but resistance and renal impairment must be considered.

Question 16

What is the advantage of using directed therapy over empirical therapy in treating bacterial infections?

Answer 16

Directed therapy is based on identifying the specific pathogen and its sensitivities, leading to a more targeted and successful treatment, often using narrower spectrum agents.
Empirical therapy, while faster, is based on probability and carries a higher risk of resistance and side effects.

Question 17

What is the role of the minimum inhibitory concentration (MIC) in antibiotic therapy?

Answer 17

MIC is the lowest concentration of an antibacterial agent that prevents visible growth of bacteria in vitro. It helps determine the most effective antibiotic and dosage for treating an infection.

Question 18

Why is it important to review the use of intravenous (IV) antibiotics within 48 hours?

Answer 18

IV antibiotics are often used in severe infections but should be reviewed to switch to oral antibiotics as soon as appropriate to avoid unnecessary IV exposure and complications.

Question 19

Why should statins be stopped temporarily during certain antibiotic treatments?

Answer 19

Antibiotics like macrolides (e.g., erythromycin) inhibit cytochrome P450 enzymes, increasing the risk of myopathy when combined with statins. Statins are usually stopped during the antibiotic course and for two days afterward.

Question 20

What is the typical approach to treating hospital-acquired pneumonia (HAP)?

Answer 20

What is the typical approach to treating hospital-acquired pneumonia (HAP)?

Question 21

What are some antibiotics with good oral bioavailability, making them effective alternatives to IV treatment?

Answer 21

Amoxicillin (75%), cefalexin (90%), ciprofloxacin (70%), and linezolid (100%) are examples of antibiotics with good oral bioavailability, allowing for easier oral administration.

Question 22

How can alcohol interact with antibiotics like metronidazole and linezolid?

Answer 22

Metronidazole can cause a disulfiram-like reaction (vomiting, flushing, abdominal pain) when taken with alcohol.
Linezolid, a monoamine oxidase inhibitor, can interact with fermented beverages like beer and wine, potentially causing adverse reactions.

Question 23

What are some clinical signs that suggest the presence of an atypical pneumonia pathogen?

Answer 23

Dry cough, lack of fever, confusion, diarrhea, and hyponatremia (seen in Legionella pneumonia)
Upper respiratory involvement, encephalitis, and skin changes (seen in Mycoplasma pneumonia).

Question 24

Why is it important to de-label inaccurate penicillin allergy records?

Answer 24

Many patients incorrectly believe they are allergic to penicillin, which limits treatment options and can lead to less effective or more toxic alternatives. Taking an accurate history and de-labelling false allergies improves patient care and supports antimicrobial stewardship.