Anti-infective Drugs

1. Anti-infective Drugs Jan Bazner-Chandler MSN, CNS, RN, CPNP

2. Bacteria

3. Bacteria • Gram-positive bacterium has a thick layer of peptioglycan. • Gram-negative bacterium has a thin peptioglycan layer and an outer membrane.

4. Common Bacterial Pathogens • Gram positive • Staphylococcus aureus • Streptocci • Enterococci • Gram negative • Escherichia coli or E-coli • Klebsiella • Proteus • Pseudomonas

5. Empiric Therapy • Administration of antibiotics based on the practitioner’s judgment of the pathogens most likely to be causing the infection; it involves the presumptive treatment of an infection to avoid treatment delay before specific cuture information has been obtained.

6. Prophylactic Antibiotic Therapy • Antibiotics taken before anticipated exposure to an infectious organism in an effort to prevent the development of infection. • IV antibiotics given prior to surgery

7. Superinfection • An infection occurring during antimicrobial treatment for another infection, resulting from overgrowth of an organism not susceptible to the antibiotic used. • A secondary infection that occurs due weakening of the patients immune system by the first infection.

8. Examples of Superinfections • Fungal or yeast infection • Diarrhea due to diminished normal flora of the gastrointestinal tract.

9. Laboratory Tests • Gram stain – microscopic identification of organism • Culture – identifies causative agent and susceptibility to specific antibiotics • Serology – titers or antibodies measured • CBC – looking at WBC

10. Cultures • Throat • Wound • Urine • Sputum • Blood

11. Clinical Pearl • Always collect culture: urine, sputum, wound drainage, or blood prior to starting antibiotic therapy. • If technician is drawing blood make sure it has been done before starting antibiotics.

12. Antimicrobials • Drugs used to prevent or treat infection caused by pathogens

13. Two Classifications • Bactericidal drugs kill bacteria directly. • Bacteriostatic drugs prevent bacteria from dividing or inhibits their growth.

14. Infectious Disease • Infections disease involves the presence of pathogen plus clinical signs and symptoms indicating infection. • Microorganisms spread by direct contact with infected person or contaminated hands, food, water, or objects.

15. Opportunistic Infections • Severe burns • Cancer • HIV • Indwelling IV catheter or urinary catheter • Corticosteroid therapy • Fungal or viral infections

16. Two Types of Bacteria • Aerobic – grow and live in presence of oxygen • Staph & Strep • Anaerobic – cannot grow in presence of oxygen • Deep wounds • Characterized by abscess formation, foul-smelling pus and tissue destruction

17. Community-Acquired Infection • Less severe and easier to treat, although drug resistant strains are increasing • Remember Staph is everywhere – it is normal flora on skin and in the upper respiratory tract • MRSA: methicillin-resistant-Staphylococcus aureus

18. Nosocomial Infections • More severe and difficult to manage because they often result from drug-resistant microorganisms and occur in clients whose resistance is impaired • Pseudomonas • Proteus

19. Bacterial Resistance • Bacteria develop the ability to produce substances which block the action of antibiotics or change their target or ability to penetrate the cells.

20. What causes resistance? • Widespread use of antimicrobial drug • Interrupted or inadequate antimicrobial treatment of infection • Type of bacteria – gram-negative strains have higher rates of resistance • Re-occurring infections • Condition of the host • Location – critical care areas

21. Client History / Assessment • Allergies • Previous drug reactions • Baseline renal and liver function • Review culture reports for appropriate antibacterial drug choice • Patient response to antibiotics therapy • Are they getting better? • Any side effects?

22. Antibiotics • Sulfonamides • Penicillins • Cephalosporins • Macrolides • Fluoroquinolones • Aminoglycosides • Tetracyclines

23. Sulfonamides • Action: inhibit the growth of bacteria (bacteriostatic antibiotic) by inhibiting the growth of susceptible bacteria by preventing bacterial synthesis of folic acid. • Usually used in combination drugs. • Trimethoprim / sulfamethoxazole: Trade name Bactrim, Septra, TMP/SMX

24. Indications • Broad spectrum: can be used against gram negative and gram positive organisms • Very useful in treating kidney infections since they achieve a high concentration in the kidneys. • Susceptible organisms: Enterobacter, E.Coli, Klebsiella, Proteus • Problem: organisms becoming more resistant

25. Specific Use of Sulfa Drugs • HIV patients with pneumocystis carinii’ • May be givenBactrim or Septra prophylactically.

26. Contraindications • Drug allergy to sulfa • Use of thiazide and loop diuretics • Pregnant women • Infants younger than 2 months of age

27. Adverse Effects • Most common is cutaneous reactions – can occur weeks after therapy started. • Erythema multiforme (Stevens Johnson Syndrome) • Toxic epidermal necrolysis • Photosensitivity reactions: exposure to sunlight can result in severe sunburn

30. B-Lactam Antibiotics • Includes 4 major drug classifications • penicillins • cephalosporins • carbapenes • monobactams

31. Penicillin • Derived from mold fungus

32. Penicillin • First generation IM or IV • Newer penicillins have been developed that increase gastric acid stability of penicillin • Good drug since it enters most bodily fluids: joint, pleural, and pericardial. • Not effective against intraocular (eye) or cerebral spinal fluid infection (CSF)

33. Penicillin • Bactericidal action against sensitive bacteria • Action: binds to bacterial wall, resulting in cell death

34. Susceptible Bacteria • Gram-positive organisms • Streptococcus • Enterococcus • Staphylococcus

35. Adverse Reactions • Most common reaction is GI (diarrhea) when administered orally. • Urticaria, pruritus, and angioedema • Severe reaction: Steven’s Johns Syndrome • Note: when giving IV or IM observe for ½ to 1 hour after giving for adverse reactions.

36. Combination Penicillin / B-lactamases • Unasyn • Augmentin • Timentin • Zosyn

37. Ampicillin – Synthetic Penicillin • Broad spectrum effective against several gram-positive and gram-negative bacteria • E-coli, proteus, Salmonella, Shigella • Not effective against staphylococci on gonococci • Bronchitis, sinusitis, and otitis media

38. Ampicillin • Bactericidal action – spectrum is broader than penicillin • Binds to bacterial wall resulting in cell death

39. Nursing Implications • Same as penicillin • Ask client about oral contraceptive use – drug may cause transient decrease in effectiveness • Advise to use additional BC – barrier protection during antibiotic therapy

40. Amoxicillin • Oral equivalent of Ampicillin • Readily absorbed and reaches therapeutic levels rapidly • Drug of choice in prevention of bacterial endocarditis • Clients with total knee or hip replacement, heart valve replacement need to take prior to any dental work, endoscopy exams

41. Dosing for Amoxicillin • Adults: 250 to 500 mg q8h • Infants and children less than 20 kg: • 20 – 40 mg / kg / day divided into doses q 8 hours

42. Cephalosporins • Widely used drug derived from fungus • Used against gram–negative bacteria • Widely absorbed and distributed in most bodily fluids – placenta and breast milk

43. Cephalosporin • First generation Cephalosporin drugs do not reach therapeutic levels in CSF (cerebral spinal fluid) but 2nd, and 3rd generation drugs do – especially important in treating meningitis

44. First Generation Cephalosporins • Bactericidal action – binds to bacterial cell wall, causing cell death • Keflex (PO) still used extensively in treatment of skin infections • Ancef – often ordered preoperatively

45. First Generation Cephalosporins • Bactericidal action – binds to bacterial cell wall, causing cell death • Keflex (PO) still used extensively in treatment of skin infections • Ancef – often ordered preoperatively

46. Keflex • First generation cephalosporin • Action: binds to bacterial cell wall membrane, causing cell death • Therapeutic effect: bactericidal action against susceptible bacteria • Active against many gram-positive cocci – step and staph

47. Client teaching • May be taken with or without food but food may minimize the GI irritation • Distribution: may cross placenta or enter breast milk in low concentrations. • Excreted entirely by the kidneys.

48. Keflex Dosing • Adults: 250 – 500 mg q 6 hours • Children: 25 – 50 mg / kg / day in divided doses q 6 h

49. Cefazolin or Ancef • Cefazolin – first generation cephalosporin • Well absorbed following IM or IV administration • Crosses to placenta and breast milk in small concentrations • Minimal CSF penetration • Excreted by kidneys

50. Ancef Dosing • IV • Used for UTI, bone and skin infections, endocarditis • Not suitable for treatment of meningitis • Perioperative prophylaxis • 1 gram within 60 minutes of incision • Post operatively every 8 hours for 24 hours (3 doses)