Antibiotics Flashcards
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Staphylococcus
Gram positive
Coccus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Streptococcus
Gram positive
Coccus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Enterococcus
Gram positive
Coccus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Peptostreptococcus
Gram positive
Coccus
Anaerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Propionibacterium
Gram positive
Coccus
Anaerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Listeria
Gram positive
Bacillus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Clostridium
Gram positive
Bacilllus
Anaerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Bacillus
Gram positive
Bacillus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Corynebacterium
Gram positive
Bacillus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Neisseria
Gram negative
Coccus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Coliforms
Gram negative
Bacillus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Haemophilus
Gram negative
Coccobacillus
Aerobic
For the following bacteria, describe
- Gram stain
- Shape
- Air requirement
Bordetella
Gram negative
Coccobacillus
Aerobic
What antibiotic classes are inhibitors of cell wall synthesis?
Beta-lactams
Glycopeptides
What antibiotic classes are inhibitors of the 30S ribosomal subunit?
Aminoglycosides
Tetracyclines
What antibiotic classes are inhibitors of the 50S ribosomal subunit?
Lincosamides
Macrolides
Fusidic acid
Linezolid
What antibiotic classes are inhibitors of folic acid synthesis?
Trimethoprim
Sulphonamides
What antibiotic classes are inhibitors of DNA gyrase?
Fluoroquinolones
What antibiotic classes are inhibitors of RNA polymerase?
Rifamycins
What antibiotic classes are disrupts of DNA strands?
Nitroimidazoles
What antibiotic classes are inhibitors of cell membrane function?
Colistin
Daptomycin
What antibiotic classes are bactericidal?
Penicillins Cephalosporins Carbapenams Glycopeptides Fluoroquinolones Rifamycins Aminoglycosides Metronidazole
What antibiotic classes are bacteriostatic?
Macrolides Lincosamides Tetracyclines Trimethoprim Sulphonamides
What sort of infection does discoloured sputum suggest?
Bacterial, rather than viral
What are the typical causes of community acquired pneumonia?
Streptococcus pneumoniae Haemophilus influenzae type b Staphylococcus aureus Streptococcus pyogenes Moraxella catarrhalis Anaerobes Aerobic and facultative Gram negative rods
What are the atypical causes of community acquired pneumonia?
Mycoplasma pneumoniae Legionella Chlamydophila pneumoniae C psittaci Chlamydia trachomatis Coxiella burnetii
What are examples of narrow spectrum penicillins?
Penicillin G Penicillin V Procaine penicillin - Procaine slows absorption rate Benzathine pencillin
What are examples of moderate spectrum penicillins?
Amoxycillin
Ampicillin
What are examples of broad spectrum penicillins?
Piperacillin
Ticarcillin
Against which bacteria do broad spectrum penicillins have?
Pseudomonas aeruginosa
When would you use broad spectrum penicillins?
If complicating factors present
What do beta-lactamase inhibitors do?
Inhibit most beta-lactamases produced by bacteria
What are examples of beta-lactamase inhibitors?
Clavulanic acid
Tazobactam
What are examples of beta-lactam/beta-lactamase inhibitor combinations?
Amoxycillin-clavulanate
Piperacillin-tazobactam
Ticarcillin-clavulanate
If a patient develops a rash within 24 hours of commencing penicillin, which antibiotics would you use?
Cephalosporins
What should you keep in mind when using cephalosporins as an alternative antibiotic in people with penicillin allergies?
Some cross-reactivity between true penicillin allergy and some cephalosporins
Rare
What are examples of first generation cephalosporins?
Oral - Cephalexin IV - Cephazolin - Cephalothin
What is the spectrum of first generation cephalosporins?
Gram positives
Some common Gram negatives; eg: E coli
What are examples of second generation cephalosporins?
Oral
- Cefuroxime
- Cefaclor
What is the spectrum of second generation cephalosporins?
Same as 1st generation
Slightly enhanced activity against Gram negatives; eg: H influenzae
What are examples of third generation cephalosporins?
IV
- Ceftriaxone
- Cefotaxime
What is the spectrum of third generation cephalosporins?
Enhanced Gram negative activity
Less Gram positive activity, especially against S aureus
What are examples of fourth generation cephalosporins?
IV
- Ceftazidime
- Cefepime
What is the spectrum of ceftazidime?
Gram negatives, including Pseudomonas aeruginosa
Poor against Gram positives, especially S aureus
What is the spectrum of cefepime?
Gram negatives, including P aeruginosa
Some Gram positive activity, including against Streptococcus and S aureus
When are fourth generation cephalosporins used a lot?
Febrile neutropaenia
What are examples of fifth generation cephalosporins?
IV
- Ceftaroline
- Ceftolozane
What is the spectrum of ceftaroline?
Gram positives, including MRSA
Gram negatives except Pseudomonas
What is the spectrum of ceftolazane?
Pseudomonas
Gram negative activity
Which antibiotic classes have intracellular activity?
Tetracyclines
Macrolides
Fluoroquinolones
What differential diagnoses should you consider when considering community acquired pneumonia?
Upper respiratory tract infections Acute exacerbation of chronic bronchitis Cardiac failure Pulmonary embolus Endocarditis Liver abscess
What antibiotic classes have Gram negative activity?
Minimal/some - Moderate spectrum penicillins - 1st and 2nd generation cephalosporins Penicillin/beta-lactamase inhibitor combinations 3rd and 4th generation cephalosporins Gentamicin Fluoroquinolones
What antibiotic classes have anaerobic activity?
Penicillin Metronidazole Beta-lactam/beta-lactamase inhibitor combinations Carbapenems Clindamycin Moxifloxacin
Why is vancomycin given orally in the treatment of Clostridium difficile?
Oral vancomycin not absorbed very well > stays in gut - where you need it
Also undergoes 1st pass hepatic metabolism, so not much enters systemically
What cause true rigors?
Influenza
Bacteria
Is there a clinical benefit in treating asymptomatic bacteriuria?
No
Exceptions
- Pregnancy
- Patients undergoing urology procedures
Why is asymptomatic bacteriuria usually not treated?
Exposes patient to complications
Promotes antibiotic resistance
Signs of splinter haemorrhages and Janeway lesions suggest what?
Infective endocarditis
What is MRSA resistant to?
All beta-lactams
Describe penicillin G
Beta-lactam
Also called benzylpenicillin
Narrow spectrum
Mainly active against Gram positive bacteria
Inactivated by beta-lactamases
IV administration
Treatment of choice for susceptible infections; eg: pneumococcal pneumonia
Describe flucloxacillin
Beta-lactamase Food impairs absorption Dosed at 6-hourly intervals Usually well tolerated Rarely associated with - Cholestatic jaundice, especially in older patients on prolonged therapy IV/oral
Describe ceftriaxone
3rd generation cephalosporin
Broad spectrum
- Including majority of community-associated enteric Gram negative rods
- Less active against Staphylococcus
Inactive against MRSA
Anti-staphylococcal activity dose dependent
Not useful against enterococci
Effective in meningitis
Risk-benefit ratio in neonates
Shouldn’t be mixed with Ca-containing IV solutions
Describe gentamicin
Aminoglycoside
Broad spectrum activity against Gram negative bacteria
- Including P aeruginosa
Describe ciprofloxacin
Quinolone Reserved for - Infections resistant to other drugs - Oral therapy when alternative antibiotics not available Broad spectrum activity against Gram negative bacteria - Haemophilus influenzae - Enteric Gram negative rods - P aeruginosa - Gram negative cocci - Some Gram positive cocci - Legionella - Several mycobacteria Not active against anaerobes Poor activity against streptococci
Describe vancomycin
Glycopeptide
Broad spectrum activity against Gram positive bacteria
Primary indication: treatment for
- MRSA
- Methicillin-resistant coagulase negative staphylococci; eg: S epidermidis
- Enterococcus faecium
Used in people with penicillin hypersensitivity
Oral vancomycin reserved for severe cases/those not responding to metronidazole when treating C difficile
- To avoid development of VRE
Describe metronidazole
Nitroimidazole Broad spectrum activity against - Gram negative anaerobic bacteria - Gram positive anaerobic bacteria - Helicobacter pylori - Protozoa Can cause disulfiram-like reaction when used with alcohol - Abstain during treatment for up to 72 hours after completing course
Describe doxycycline
Tetracycline
Broad spectrum
- Gram positive and negative bacteria
- Chlamydia
- Rickettsia
- Mycoplasma
- Spirochetes
- Some non-TB mycobacteria
- Some protozoa; eg: malaria-causing Plasmodium
Can cause oesophagitis
Should be taken with food and full glass of water
Can cause photosensitivity
Tooth discolouration and enamel dysplasia in children
- Reactions minimal if single short courses used
Describe acyclovir
Nucleic acid analogue Primarily used for treatment of - HSV - Chickenpox (VZV) - Shingles (VZV) Other uses - Prevention of CMV infections after transplant - Severe complications of EBV IV/oral
