Infections Lecture 2: Bacterial Infections, anti-bacterial agents and mechanisms of action Flashcards
What are the symptoms of a bacterial infection?
Malaise, fever and chills
What are the two different types of bacteria?
- Gram +ve- thick peptidoglycan
2. Gram -ve- thin peptidoglycan
How does penicillin work? And where is it excreted mainly?
- Bactericidal that inhibits cell wall synthesis by interfering with peptidoglycan and it acts as a bactericidal
- Excreted mainly in the bile and urine
How do cephalosporins (beta lactams) work? And where are they excreted mainly? What are the side effects?
- Bactericidal that interfere cell wall synthesis by interfering with peptidoglycan synthesis after binding to the Beta-lactam-binding proteins
- Excreted mainly in urine
- Side effects: Nephrotoxicity, diarrhoea, similar to penicillin
How do Fluoroquinolones work? And where are they excreted mainly?
- Bactericidal that inhibits DNA gyrase
2. Excreted by kidneys and metabolised by liver
How do Aminoglycosides work? And where are they excreted mainly?
- Bactericidal inhibit protein synthesis
2. Excreted unchanged in urine
How do Tetracyclines work? And where are they excreted mainly? What are the unwanted side effects?
- Bacteriostatic inhibit protein synthesis
- Excreted mainly in urine
- Side effects: GI disturbances, staining growing teeth and bone deformities
How do Metronidazole work? And where are they excreted mainly?
- Bactericidal are toxic to cells by interfering with electron transport/producing free radicals
- Metabolised in liver
How does Chloramphenicol work? And where are they excreted mainly?
- Bacteriostatic folate antagonist/inhibits folate synthesis
- Metabolised in liver and excreted in kidney
How does sulphonamides work? What are the unwanted side effects and its clinical use?
- Targets folate synthesis pathways by competing with PABA which is an essential precursor in folic acid synthesis in bacteria
- Side effect: nausea, vomiting, headaches, rashes
- Used in UTIs and eye infections
Give examples of the main antibiotics that affect the cell wall synthesis
Penicillin, Beta-lactamase inhibitors, Carbapenems
How does Trimethoprim work, what are the side effects and the clinical uses of it?
- An agent that interferes with the synthesis or action of folate by acting as a folate antagonist
- Side effects: Nausea, vomiting, blood disorders and skin rashes
- Clinical use: Urinary and respiratory tract infection
What does bacteriostatic mean?
Inhibits the growth of bacteria but doesn’t kill them
What are the clinical uses of penicillin? Give the main examples and their uses?
- Severe infections of sensitive organisms (bacterial meningitis): benzylpenicillin
- Bone and Joint infections (staphylococcus auereus): Flucloxacillin
- Skin and soft tissue infections (staphylococcus auereus): Benzylpenicillin, flucloxacillin, PHENOXYLMETHYLPENICILLIN
- Otitis media: amoxicillin
- Bronchitis: amoxicillin
- Pneumonia: amoxicillin
What are the clinical uses of cephalosporins? Give the main examples and their uses?
- Septicaemia (cefuroxime, cefotaxime)
- Meningitis (ceftriaxone, cefotaxime)
- Urinary tract infection (pregnancy)- Cefalexin
What are the clinical uses of tetracyclines? And what is a common drug form of it?
- Rickettsial and chlamydial infections, brucellosis, anthrax and lyme disease
- Doxycycline
What are the clinical uses of chloramphenicol? Give the main examples and their uses?
For serious infections where benefit of drug outweighs haematological toxicity such as
- Haemophilus influenzae resistant to other drugs
- Meningitis in patients when penicillin cannot be used
- Safe for “Bacterial conjunctivitis (topical)”
What are the clinical uses of aminoglycosides? And what are the unwanted side effects?
- Effective against many aerobic G-ve and some Gram +ve
- Mainly gram -ve enteric organisms
- Sepsis
- Unwanted side effects: Ototoxicity and nephrotoxicity
How do macrolides work and give some example of the main drugs
- Inhibit protein synthesis, bactericidal or bacteriostatic (concentration and organism)
- Erythromycin (main one), Clarithromycin, Azithromycin, Spiramycin, Telthromycin
What are the clinical uses of streptogramins and give some example of the main drugs?
- Mostly Gram -ve enteric organisms
- Treatment of severe infections in combination
- Examples: Quinupritsin and Dalfropristin
What are the clinical uses of Lincosamides and give some example of the main drugs?
- Bone and joint infections.
2. Clindamycin- Gram +ve cocci (penicillin resistant staph)
What are the fluroquinolines clinical uses?
- Complicated urinary tract infection
- Gonorrhoea
- Bacterial Prostatitis
- Anthrax (ciprofloaxin)
Affect the DNA gyrases
What is the antibiotic mechanism for Glycopeptides? Give the 2 examples of the drug and what are its clinical uses?
- Inhibit cell wall synthesis
- Examples: Vancomycin and teicoplanin
- IV for multi-resistant staphylococcal infections
- Orally: Clostridium Difficile
What is the antibiotic mechanism for polymyxins? Give the example of a drug and what are its clinical uses?
- Disrupts bacterial cell membrane
- Colisitin
- Only used topically
