Action

Uses

Penicillins were first used on a wide scale in the 1940’s and were the main antibiotics for many years. Penicillin is the broad-spectrum drug of choice for susceptible gram-positive and gram-negative organisms. Penicillins are considered the safest antibiotics.

There are many penicillin products, including oral amoxicillin to injectable procaine penicillin. The choice of drug to give a patient depends on the infectious bacteria (as identified by cultures or smears) or on the basis of the clinical picture. Penicillin is effective in the treatment of the following susceptible organisms: alpha-hemolytic streptococci; group A beta-hemolytic streptococci; streptococci belonging to groups C, G, H, L, and M; and Spirillum minus (rat-bite fever), Treponema pallidum (syphilis), Clostridium perfringens, Clostridium tetani, Corynebacterium diphtheriae, Staphylococcus, Pasteurella meningitidis, and other less common organisms. Penicillin is also used for prophylactic (preventive) treatment against bacterial endocarditis in patients with rheumatic or congenital heart disease before they have dental procedures or surgery of the upper respiratory tract, genitourinary tract, or GI tract. Some penicillins may be useful against organisms used by terrorists as bioweapons.

As broad spectrum antibiotics, penicillin has been used for almost every type of infection, including those for which they were not effective. Over the years, overuse and inappropriate use of penicillin has led to the development of penicillin-resistant strains of disease. These penicillin-resistant strains of bacteria produce a chemical called penicillinase. β-lactamase (penicillinase) is an enzyme that disrupts the internal structure of penicillin and thus destroys the antimicrobial action of the drug. Although penicillin continues to be an important antibiotic, research on penicillin has led to the identification of many other types of antibiotics that may now be used to control infection.

Adverse Reactions

Adverse reactions to penicillin are many. Major reactions include neuropathy (nerve damage in a variety of places and seen with high parenteral dosages), fixed drug eruptions (usually a single spot that itches), nausea, vomiting, epigastric distress, anemia, and blood dyscrasias. Allergy to penicillin has also become a problem, producing rash, erythema (redness or inflammation), urticaria (hives), angioedema (swelling of the skin and mucous membranes), laryngeal edema (swelling of the larynx), and anaphylaxis (shock). These allergic reactions may occur suddenly or after the patient has been taking the medicine for some time and may be life threatening. They may occur up to 10% of the time in patients taking penicillin products.

Drug Interactions

Other bacteriostatic antibiotics such as tetracycline and erythromycin may decrease the bactericidal effect of penicillin. Probenecid prolongs blood levels of penicillin by blocking its renal clearance. Use of ampicillin and oral contraceptives together has produced menstrual irregularities and unplanned pregnancies because penicillin reduces the level of available hormone. Indomethacin, phenylbutazone, or aspirin may increase serum penicillin levels. Antacids may decrease the absorption of penicillin. Penicillin may change the results of some laboratory tests. For example, penicillin may cause increased bleeding time when the platelet count is normal, giving a false positive urine protein test and lupus erythematosus cell test.

Nursing Implications and Patient Teaching

The patient in need of antibiotic therapy may vary from being asymptomatic (showing no symptoms) to being severely ill. Look for common clues to infection, such as fever, redness, swelling, or pain.

Ask whether there is a prior history of penicillin allergy, asthma, or hypersensitivity (allergy) to procaine or tartrazine, and find out if the patient is pregnant or breastfeeding. These conditions may be contraindications or precautions to the use of penicillin. Anaphylactic (shock) reactions have occurred with both oral and parenteral penicillin therapy. Penicillin should be used with caution in patients who have many other drug allergies.

With intramuscular (IM) injections, follow institutional policy about whether to aspirate (pull back on the plunger of the syringe to check for blood) to prevent medicine from accidentally being injected into a blood vessel.

Patients often spread infections to family or friends. For example, the sexual partners of patients infected with syphilis or gonorrhea must be treated also.

Penicillin changes the results of many laboratory tests, so while the patient is on penicillin therapy, the results of laboratory culture and sensitivity tests, as well as many other laboratory findings, may be incorrect.

Action

The tetracyclines are bacteriostatic agents. They act by interfering with the ability of the bacterial to make protein. Without this protein, the bacteria cannot stay alive.

Uses

Adverse Reactions

The tetracyclines are relatively safe, with very few serious adverse effects. They commonly produce mild episodes of nausea, vomiting, and diarrhea that may require stopping the drug. These effects are often dose related, and they result from GI irritation, changes in the normal bacteria in the bowel, and overgrowth of yeast.

The use of tetracycline in pregnancy and in children younger than 8 years of age may produce permanent yellow-brown tooth discoloration or inadequate bone or tooth development.

Photosensitivity may occur with tetracycline treatment, so the patient should avoid exposure to the sun or ultraviolet rays. Pregnant women should not use tetracyclines because they are category D agents which may damage the fetus.

Tetracycline should be used with caution in patients with poor liver function, because the drug may cause hepatotoxicity.

Superinfections may develop, particularly after long-term use. These reactions, such as diarrhea, oral thrush (Candida infection of the mouth), or vaginal itching, are usually irritating but mild. At other times, the superinfection may become life threatening. Overgrowth of organisms is commonly seen in AIDS patients, whose immune systems may be totally overwhelmed by a mild superinfection.

Vertigo may develop with the use of any of the tetracyclines; however, vertigo is more common with the use of minocycline.

Drug Interactions

Patients should not drink milk or take any dairy or calcium while taking these medications. Tetracyclines bind with calcium and iron and may reduce the drug’s absorption up to 50%. Tetracycline is best taken with water on an empty stomach 1 hour before eating or 2 hours after eating.

Nursing Implications and Patient Teaching

Tetracycline products that are out of date (older than the expiration date on the label) should not be used, because it may lead to damage of the proximal renal tubules.

Doxycycline (Vibramycin) is a particularly good drug, especially for the older adult population because it may be taken twice daily and is usually tolerated even by some individuals who have reduced renal function.

Action

Macrolides such as erythromycin are either bacteriocidal or bacteriostatic depending on the organisms and the dose used. Marcolides weaken the bacteria by limiting the production of protein, which is essential to the life of the bacteria.

Uses

The macrolides are used as alternatives to penicillin for many infections for which organisms have developed penicillin resistance. They are the drugs of choice in Streptococcus infections, Haemophilus influenza, Mycoplasma pneumoniae, and Chlamydia infections. They are also used in legionnaires disease and in the treatment of pertussis (“whooping cough”).

Adverse Reactions

Macrolides are associated with very few serious side effects. They are often considered a safe first choice for patients with uncomplicated infection. Mild abdominal pain, nausea, and diarrhea are the most common effects. Watch for signs of superinfection.

Nursing Implications and Patient Teaching

The major differences between erythromycin and the newer macrolides include better GI tolerability, a broader spectrum of activity, and less dosing frequency for the newer products. Giving the medication with food reduces GI irritation.

Caution should be used when this drug is given with any other medication because of the risk of drug-drug interactions and increase of adverse effects.

The strength of erythromycin varies by product. The strength of different products are reported as the erythromycin base equivalence. Because of differences in absorption, 400 mg of ethylsuccinate is required to provide the same free erythromycin serum levels as 250 mg of erythromycin base, stearate, or estolate. This accounts for the differences in doses of different erythromycin products.

Many macrolides may be administered orally or parenterally. Topical application should be avoided to prevent sensitization. The patient should be kept well hydrated (supplied with fluids). Drinking extra fluids to ensure a minimum urine output of 1500 mL decreases the chances of renal toxicity.

All chewable forms of erythromycin must be fully chewed to obtain the complete therapeutic effect.

Action

Aminoglycosides weaken the bacteria by limiting the production of protein, which is essential to the life of the bacteria.

Uses

These products, such as gentamycin and amikacin, are used in the treatment of serious aerobic gram-negative infections, including those caused by Escherichia coli, Serratia, Proteus, Klebsiella, and Pseudomonas; aerobic gram-negative bacteria, mycobacteria, and some protozoans. Streptomycin (SM) is used in the treatment of TB. Some products are used to sterilize the bowel before intestinal surgery.

Adverse Reactions

Aminoglycosides may cause serious adverse effects including damage to the kidney (nephrotoxicity) that is usually reversible if the drug is stopped quickly. They may also produce permanent damage to the inner ear (ototoxicity), hearing impairment, dizziness, loss of balance, ringing in the ears, and persistent headache. Aminoglycosides have a narrow therapeutic range, so the blood levels of these drugs should be closely watched to avoid toxic levels. Dosage is calculated on the basis of the patient’s weight and is increased or decreased based on blood levels so an effective level is maintained. The narrow therapeutic range (when the lowest and highest acceptable drug levels are not far apart) requires that the sample for the antibiotic blood level be drawn just before the next scheduled dose is given. This sample will show the lowest blood level of the antibiotic (found at the “trough”), rather than a blood level at a higher range (at or near the “peak”). The lowest blood level will determine whether the dosage needs to be adjusted to stay within the therapeutic range and not go above the toxic level or below the effective level. Because of the nephrotoxicity of these agents, blood urea nitrogen and creatinine levels must also be monitored during the course of therapy.

Drug Interactions

Using this drug with many products, particularly vancomycin, increases the risk of nephrotoxicity. Ototo­xicity is also increased with aspirin, furosemide, ethacrynic acid, and many other drugs.

Nursing Implications and Patient Teaching

Some of these products are available over-the-counter (OTC) or by prescription for eye, ear, or skin infections. When given for systemic bacterial infections they must be given parenterally as they are poorly absorbed from the GI tract.

Patients should have frequent hearing and urine tests to monitor for nephrotoxicity and ototoxicity.

Action

Fluroquinolones are bacteriocidal and act by interfering with bacterial DNA synthesis, which makes it difficult for the pathogens to reproduce themselves and attack other cells.

Uses

There are four generations of fluoroquinolones, which are all effective against gram-negative pathogens. The newer ones are significantly more effective against gram-positive microbes. These agents are used as alternatives to other antibiotics in the treatment of respiratory, GI, gynecologic, skin, and soft-tissue infections. Ciprofloxin (Cipro) is the drug of choice for anthrax exposure in a bioterrorist attack.

Drug Interactions

Fluoroquinolones should not be taken with multivitamins or mineral supplements because they reduce the absorption of the antibiotic by as much as 90%. When taken with warfarin, fluoroquinolones will increase warfarin’s anticoagulant effects. Antacids and ferrous sulfate may decrease absorption of the drugs. Patients may develop excessive nervousness, anxiety, or tachycardia if taken with coffee or other caffeine-containing products.

Nursing Implications and Patient Teaching

Fluoroquinolones are well absorbed orally and may be given only once or twice per day. Take drug with food to decrease adverse GI effects.

Action

Cephalosporins are bactericidal and weaken the bacteria by interfering with building of the bacteria’s cell wall.

Uses

There are four generations of cephalosporins, all of which have broad spectrum activity against gram-negative organisms. In general, second- and third-generation drugs are more effective and more potent than first-generation agents against a broad group of gram-negative organisms; however, they are also less effective against gram-positive organisms. Third-generation agents are also more effective against inact­ivation by beta-lactamase (an enzyme that some organisms make to protect them against the action of some antibiotics). However, these agents cost more and may have more side effects. Differences among drugs within categories are primarily based on the drug’s activity. Later-generation drugs are more effective against some of the organisms to which earlier generation agents have been resistant.

Cephalosporins are used for serious infections, like bacteremia and septicemia (infections of the blood); and infections of the lower respiratory tract, central nervous system (CNS), genitourinary system, joints, and bones. These drugs are also used in patients who cannot take penicillin.

Adverse Reactions

Nausea, vomiting, and diarrhea are frequent. The most common adverse effect is acute hypersensitivity. Although some patients may have only a minor rash and itching, anaphylaxis is possible. There may be severe pain at the injection site. Nephrotoxicity has been reported with some cephalosporins, and the incidence is greater in older adult patients and in patients with poor renal function.

Drug Interactions

Alcohol taken with these products may produce a severe disulfiram reaction resulting in severe flushing, vomiting, and collapse. Other products, such as probenecid, may decrease elimination of the drugs by the kidneys.

Nursing Implications and Patient Teaching

Must be given by the IV or IM route because it is not absorbed from the GI tract.

Patients who have had a recent and severe reaction to penicillin should not be prescribed these products.

Action

Sulfonamides have a bacteriostatic effect against a wide range of gram-positive and gram-negative microorganisms by inhibiting folic acid synthesis, which is essential for cell growth and function.

Uses

Sulfonamides are usually used to treat acute and chronic urinary tract infections, particularly cystitis, pyelitis, and pyelonephritis caused by E. coli or Nocardia asteroides. Other indications include toxoplasmosis, acute otitis media caused by H. influenzae, and preventive therapy in cases of recurrent rheumatic fever. Susceptible organisms include Streptococcus pyogenes, Streptococcus pneumoniae, some strains of Bacillus anthracis, C. diphtheriae, Haemophilus ducreyi, Chlamydia trachomatis, and other less common organisms. Several sulfonamides are useful only in the treatment of ulcerative colitis, and as preoperative and postoperative therapy for bowel surgery.

Adverse Reactions

Adverse reactions to sulfonamides include many minor but irritating problems such as headache, drowsiness, fatigue, dizziness, vertigo (feeling of dizziness or spinning), tinnitus (ringing in the ears), hearing loss, insomnia (inability to sleep), anorexia (lack of appetite), nausea, vomiting, stomatitis (inflammation of the mouth), abdominal pain, rash, fever, malaise (weakness), pruritus (itching), dermatitis, local irritation, anaphylactic shock, crystalluria (formation of crystals in the urine), hematuria (blood in the urine), and proteinuria (large amounts of protein in the urine) may develop with overdosage and indicate that the patient may have a severe hypersensitivity to sulfonamides.

Drug Interactions

Sulfonamides may increase the effect of oral anticoagulants, methotrexate, sulfonylureas, thiazide diuretics, phenytoin, and uricosuric agents. Many other drugs taken at the same time will cause the effects of sulfonamides to be increased. Penicillins may be less effective when given with a sulfonamide. The sulfonamide’s effect may be decreased by local anesthetics. Antacids may cause less absorption of the sulfonamide. Sulfonamides may change the results of various laboratory tests including urine glucose.

Nursing Implications and Patient Teaching

Warn the patient to stay out of the sun, because severe photosensitivity (abnormal response to exposure to sunlight) can occur if the patient’s skin is exposed to excessive amounts of sunlight or ultraviolet light.

Sulfonamide dosage depends on the severity of the infection being treated, the drug used, and the patient’s response to and tolerance of the drug. Generally, the short-acting sulfonamides are given at more frequent intervals than are the intermediate- or long-acting sulfonamides. Also, short-acting sulfonamides usually require a special first dose (initial loading dose) that is larger than the dose that will be regularly taken.

Sulfonamides are more fully and quickly absorbed when they are taken on an empty stomach. They should be taken either 1 hour before or 2 hours after meals, along with a full glass of water.

To prevent formation of crystals in the urine, the patient must drink large amounts of water while taking this medication.

It is particularly important with these drugs that the patient should take all the medication prescribed and not stop just because the symptoms have disappeared, so they do not have a relapse.

The health care provider should be notified quickly if a skin rash, blood in the urine, bruises, nausea, or other adverse effects of therapy develop because these may indicate development of more severe reactions.