Normal gut flora are killed which produces diarrhea and can pave the way for colonization with pathogenic bacteria.
Suprainfection – infection with a second (antibiotic resistant) organism that occurs during antibiotic therapy. In pseudomembranous colitis, the bowel is colonized with Clostridium difficile , producing a severe diarrhea that is sometimes fatal.
I. Antibiotics Affecting the Bacterial Cell Wall: Beta-Lactam Antibiotics
Beta-lactam antibiotics penetrate the cell wall and bind to targets on cytoplasmic membrane
Disrupt synthesis/maintenance of the cell wall: bacterium is killed by osmotic pressure.
Can be inactivated by beta-lactamases: enzymes that degrade the drug.
Gram-negative organisms have an additional component to their cell wall that most beta-lactam antibiotics cannot penetrate. Therefore, most of these agents are not effective against gram-negative bacteria.
Therapeutic: used for gram-positive bacteria such as Strep and Staph & a few gram-negatives such as Neisseria, and syphilis ( Treponema ). Some will cover anaerobes such as Enterobacter & also Pseudomonas , and Klebsiella .
Prophylactic: used to prevent bacteremia in selected populations at risk for endocarditis, such as people with artificial or damaged heart valves.
Individual penicillins have varying resistance to beta-lactamases (bacterial enzymes that break apart the beta-lactam ring).
activity, susceptibility to beta-lactamases, and uses.
Widely distributed to body fluids including bone
1 st and 2 nd generations do not cross blood-brain barrier.
Most eliminated by the kidney: may need decreased dose with decreased renal function
Major Differences between Cephalosporin Generations Lehne, 2007, Pharmacology for Nursing Care, 6 th ed., Elsevier, p. 973 Generation Activity against Gram Negative Resistance to Beta-Lactamases Distribution to CSF 1 st (e.g., cephalothin) Low Low Poor 2 nd (e.g., cefamandole) Higher Higher Poor 3 rd (e.g. cefotaxime) Higher Higher Good 4 th (e.g. cefepime) Highest Highest Good
Poor absorption of some: all form insoluble compounds with calcium, iron, magnesium, aluminum and zinc. So don’t give with antacids/laxatives, milk/dairy, iron.
Bind to calcium in developing teeth and form a discolored area. So don’t give to pregnant women (will only affect baby teeth) or children below 8 years.
Suprainfection with bowel organisms or Candida
Tetracycline-Stained Teeth http://www.wisconsinreconstructiveimplantdentist.com/images/tetracycline4.jpg The patient was treated with tetracycline while the permanent teeth were developing. Dark staining is present in the parts of the teeth that were forming during treatment.
Can cause irreversible joint disease in children <18.
Rarely, tendon rupture in adults.
Candida suprainfections, especially of the oropharynx.
Infrequent but serious CNS effects.
Vyas H and Krishnaswamy G. N Engl J Med 2007;357:2067 An 81-year-old woman with rheumatoid arthritis, Sjogren's syndrome, and hypertension presented with swelling and pain in the area of the left heel, which had developed suddenly a week after a short course of levofloxacin for acute bronchitis
HIV is always treated with combinations of drugs. The current combinations are collectively referred to as ART ( A nti- R etroviral T herapy), ARV ( A nti- R etro v irals) or HAART (highly active antiretroviral therapy). To avoid development of viral resistance, it is very important that patients receiving HAART take their medications reliably and on time.
Skipping doses can have devastating results, both for the individual patient and for society if the patient infects someone else with a resistant strain of virus.
Because the medications have a variety of side effects that can be very bothersome, it may be tempting to patients to discontinue treatment when they feel better.
Pregnant patients who would otherwise receive treatment should receive it while pregnant, although particular drugs might have to be avoided.
Treatment of the patient’s infection will reduce viremia and thereby reduce the risk of transmission to the fetus.
In women who have not received therapy during pregnancy, RT inhibitors can be given during labor, and to both mother and child after delivery. This strategy reduces maternal to fetal transmission dramatically.
PMTCT programs = Prevention of Mother to Child Transmission.
Work at same stage in the replication cycle but in different ways
I. Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
Inhibit viral enzyme, reverse transcriptase, that converts viral RNA into DNA, by terminating the growing DNA strand. This activity can also inhibit human DNA polymerases so these drugs are toxic to dividing cells.
Zidovudine (AZT), ddi, ddc, 3tc, d4t and others.
Can cause mitochondrial toxicity in liver (hepatomegaly and fatty liver) and elsewhere leading to lactic acidosis.
Bone marrow depression, anemia, neutropenia.
All have GI toxicity – stomatitis, nausea, diarrhea, etc.
All are metabolized by cytochrome P450 enzymes. Concurrent administration with inducers or inhibitors of cytochrome P450 can affect half-lives and drug levels (recall that the non-nucleoside RT inhibitors have varying effects on the cytochrome P450 enzymes). See table 93-6 in Lehne.
St. John’s wort and garlic preparations should be avoided.
Most have GI side effects similar to the nucleoside and non-nucleoside RT inhibitors.
Therapy for HIV infection is complicated and drugs have significant toxicity and interactions with other drugs.
Management of HIV-infected patients is best done by health care providers who are very experienced with these drugs and their side effects.
When HIV-infected patients are hospitalized on general medical or surgical floors, nurses must become knowledgeable about the patient’s regimen and how it might interact with other drugs the patient might be given as part of his/her hospital treatment.