Antibiotics Flashcards
A patient has been experiencing a cough for the past 2 weeks. He coughs up green sputum, has a fever, bp is 125/85mmhg. On exam, lymphadenopathy is present. What is the diagnosis?
Pneumonia
DISCUSS PENICILLIN CLINICAL PHARM
MOA:
Penicillins inhibits the enzymes that cross peptidoglycans in bacterial cell.
This weakens cell walls, preventing them from maintaining an osmotic gradient
The water causes cell swelling, lysis and death. Penicillins contain a β-lactam ring, which is responsible for their bactericidal activity.
Drugs:
amoxicillin, co-amoxiclav
Indications:
Amoxicillin used for susceptible infections, community-acquired pneumonia, otitis media, sinusitis and urinary tract infections
Helicobacter pylori-associated peptic ulcers
Severe, resistant and hospital-acquired infections (respiratory tract infection, genitourinary and abdominal infections
Adverse effects:
- Gastrointestinal (GI) upset, Stomach upset, diarrhoea
- Antibiotic-associated colitis (Clostridium difficile)
- Skin rash
- Anaphylactic reaction (Swelling of the throat,lips)
- Acute liver injury
- Jaundice
Warnings/caution:
- ▴C. difficile infection
- ▴penicillin-associated liver injury
- ▴severe renal impairment
Contraindications:
- ✗history of allergy
Interactions:
- Enhance the anticoagulant effect of warfarin by killing normal gut flora that synthesise vitamin K
Monitoring:
- Check that infection resolves by resolution of symptoms, signs (e.g. pyrexia, lung crackles, dysuria) and blood markers (e.g. falling C-reactive protein and white cell count) as appropriate.
What medication treats tonsilitis.
Phenoxymethylpenicillin
A patient arrives to the GP with a swollen area around his arm. On exam, the arm is erythemous, pus filled and warm to touch. What is this infection called?
What medication do you treat osteomyelitis?
Staphylococcus aureus
Flucloxacillin for skin infection usually 500mg 3 times a day for 7 days
Flucloxacillin for osteomyelitis for 6 weeks
DISCUSS FLUCLOXACILLIN CLINICAL PHARM
MOA:
Same moa as general penicillin. This is just narrow spectrum against Gram-positive staphylococci. Flucloxacillin effective against β-lactamase-producing staphylococci.
Indications:
Skin and soft tissue infections such as cellulitis
Osteomyelitis and septic arthritis
Endocarditis
Adverse effects:
- GI upset
- Skin rash
- Anaphylactic reaction
- Liver toxicity
Warning/caution:
- ▴renal failure
- ▴hepatic impairment
Contraindications:
- ✗history of penicillin allergy
- ✗prior flucloxacillin-related hepatotoxicity
Interactions:
- Penicillins reduce renal excretion of ▴methotrexate, increasing the risk of toxicity.
Monitoring:
Check that infection resolves by resolution of symptoms, signs (e.g. pyrexia, erythema of cellulitis) and blood markers
A patient comes to your gp clinic with worsening abdominal pain. She has tested positive for the H.pylori bacteria. How do you manage this?
Eradication, Omprazole, amoxicillin 1g and clarithromycin 500mg or metrodnidazole 400mg 7 days, twice daily
If allergic to penicillin: omeprazole, clarithromycin 250mg or metrodnidazole 400g
DISCUSS CLARITHROMYCIN CLINICAL PHARM
MOA:
- Macrolides inhibit bacterial protein synthesis, and block translocation.
- Inhibition of protein synthesis is bacteriostatic (stops bacterial growth)
- Bacterial resistence due to ribosomal mutations preventing macrolide binding
Drugs:
- Clarithromycin, erythromycin, azithromycin
Indications:
- Respiratory, skin and soft tissue infections
- severe pneumonia such as Legionella. p and Mycoplasma. p
- Eradication of Helicobacter pylori, peptic ulcer disease
Adverse effects:
- Irritant causing nausea, vomiting, abdominal pain, diarrhora
- Antibiotic-associated colitis
- Cholestatic jaundice, Prolongation of the QT interval arrhythmias risk and ototoxicity
Warnings/cautions:
- Severe hepatic and liver impariment
Contraindications:
✗macrolide hypersensitivity
Interactions:
- ▴drugs metabolised by CYP enzymes
- ▴drugs that prolong the QT interval (SSRIs, antipsycotic)
Monitoring:
Check that infection resolves by patient report (e.g. resolution of symptoms), examination (e.g. resolution of pyrexia, lung crackles) and blood tests
DISCUSS METRONIDAZOLE CLINICAL PHARM
MOA:
- In anaerobic bacteria, reduction of metronidazole generates a nitroso free radical.
- This binds to DNA, reducing synthesis and causing widespread damage, DNA degradation and cell death (bactericidal).
Indications:
- Antibiotic-associated colitis clostridium difficile
- Oral infections Aspiration pneumonia
- Surgical and gynaecological infections
- Protozoal infections (trichomonal vaginal infection)
Adverse effects:
- GI upset nausea and vomiting
- Hypersensitivity reactions
- Peripheral optic neuropathy
- Seziures
- Encephalopathy
Warnings/caution:
- Severe liver disease
Contraindications:
- Alcohol
Interactions:
- CYP enzymes, reducing metabolism of warfarin (increasing the risk of bleeding)
- CYP inducers (e.g. phenytoin, rifampicin), resulting in reduced plasma concentrations efficacy
Monitoring:
- Warn patients not to take alcohol during or for 48 hours after treatment, explaining that if they do they may feel very unwell with nausea, vomiting, flushing and headache.
- Check that infection resolves by review of symptoms, signs and blood tests
A patient came in with Dyspareunia, Dysuria, Vaginal discharge (yellow/green purulent with odour), Post coital bleeding, Intermenstrual bleeding May present with an inflamed cervix, cervical discharge, abdominal tenderness, pelvic tenderness. What is the diagnosis and how do you treat it?
Chlamydia
DISCUSS TETRACYCLINES CLINICAL PHARM
- Drugs: Doxycycline, lymecycline
MOA:
- Tetracyclines inhibit bacterial protein synthesis by binding to 30S subunit.
- Inhibition of protein synthesis is bacteriostatic (stops bacterial growth), which assists the immune system in killing and removing bacteria from the body
Adverse effects:
- Nausea, vomiting, diarrhoea
- Hypersensitivity reaction
- Oesophageal irritation, ulceration and dysphagia
- Photosensitivity
- Discolouration (Staining) and/or hypoplasia of tooth enamel (Small tooth)
- Hepatotoxicity and intracranial hypertension
Warnings/Cautions:
- ▴renal impairment
Contraindication:
- ✗pregnancy,
- ✗breastfeeding
- ✗children ≤12 years of age.
Interactions:
- They should therefore not be given within 2 hours of calcium, antacids or iron, which will prevent antibiotic absorption
- enhance the anticoagulant effect of warfarin
Monitoring:
- Advise patients to take the treatment during a meal with a full glass of water when sitting or standing. They should avoid indigestion remedies
- Check that infection resolves by resolution of symptoms, signs
A youngn patient has been exhibiting urinary symptoms. Burning on urination, frequent urge to go, cloudy, dark or has a strong smell. What does this patient have?
- Trimethroprim
DISCUSS TRIMETHOPRIM CLINICAL PHARM
Drug names:
Trimethoprim, co-trimoxazole
MOA:
-Trimethoprim inhibits bacterial folate synthesis, slowing bacterial growth (bacteriostasis).
Indications:
- Acute lower urinary tract infection (UTI).
- Prophylaxis of recurrent UTI. Alternatives include nitrofurantoin, amoxicillin and cefalexin
- the treatment of acne, respiratory tract infections and prostatitis
- prevention of pneumocystis pneumonia (immunosuppresant individuals)
Adverse effects:
- GI upset (nausea, vomiting and sore mouth)
- Skin rash
- Severe hypersensitivity
- haematological disorders (megaloblastic anaemia)
- Hyperkalaemia
Warnings/cautions:
- ▴folate deficiency
- ▴renal impairment;
- ▴HIV infection
- ▴Neonates
- ▴elderly
Contraindications:
- ✗first trimester of pregnancy
Interactions:
- ▴potassium-elevating drugs (e.g. aldosterone, ACEi
- ▴folate antagonists (e.g. methotrexate)
- ▴drugs that increase folate metabolism (e.g. phenytoin)
Monitoring:
Check that acute infection resolves by resolution of symptoms (e.g. reduction in dysuria), signs (e.g. resolution of pyrexia) and investigations
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DISCUSS NITROFURANTOIN CLINICAL PHARM
Drugs: Nitrofurantoin
MOA:
- Its active metabolite damages bacterial DNA and causes cell death (bactericidal).
Adverse effects:
- GI upset (including nausea and diarrhoea)
- hypersensitivity reactions
- can turn urine dark yellow or brown.
- chronic pulmonary reactions
- peripheral neuropathy prolonged use
- neonates, haemolytic anaemia
Warnings/cautions:
- ▴long-term prevention
Contraindications:
- ✗pregnant women towards term (Tetragenic)
- ✗babies in the first 3 months of life.
- ✗renal impairment
Interactions:
- no common interactions
Monitoring:
- Efficacy of treatment for acute UTI is determined by resolution of symptoms
- Advise them that their urine colour may change to dark yellow or brown during treatment; this is harmless and temporary. Also pins and needles can later go on to cause further issues
A patient recent dental work, which was a tooth extraction 2 days ago. After some days he started to experience the following: Fever, chest pain, Dizziness, weakness, Arthralgia. What does he have and how do you manage it?
Endocarditis
DISCUSS VANCOMYCIN CLINICAL PHARM
MOA:
- Vancomycin inhibits growth and cross-linking of peptidoglycan chains, inhibiting synthesis of the cell wall of Gram-positive bacteria, thus lysing and killing the bacteria (bactericidal)
Adverse effects:
- thrombophlebitis
- red man syndrome’
- immediate or delayed hypersensitivity
- nephrotoxicity
- ototoxicity
- hearing loss
- neutropenia and thrombocytopenia.
Warning/cautions:
- ▴renal impairment
- ▴elderly (increased risk of hearing impairment)
Contraindications:
Inflammatory disorders of the intestinal mucosa or Clostridium difficile-induced
Interactions:
- Vancomycin increases the risk of ototoxicity and/or nephrotoxicity when prescribed with ▴aminoglycosides, ▴loop diuretics or ▴ciclosporin
Monitoring:
- renal function. Platelet and leucocyte counts should be monitored in prolonged courses.
- if ringing or hearing loss occurs in the ears, medication should be stopped.
