Medication Summary
Medical therapy is directed at eradication of the infecting Providencia organism with an antimicrobial agent to which the organism is susceptible.
Antibiotics
Class Summary
Selection of empiric antimicrobial therapy must take into account the likely pathogens given the clinical setting. Selection of final antimicrobial therapy, once the identity of the infecting organism is known, should favor the safest and most cost-effective agent with the narrowest spectrum of activity to which the infecting pathogen is susceptible.
Aztreonam (Azactam)
A monobactam (not a beta-lactam) antibiotic that inhibits cell wall synthesis during bacterial growth. Active against gram-negative bacilli but very limited gram-positive activity and not useful for anaerobes. Lacks cross-sensitivity with beta-lactam antibiotics. May be used in patients allergic to penicillins or cephalosporins.
Duration of therapy depends on severity of infection and should be continued for at least 48 h after symptoms resolve asymptomatic or evidence of bacterial eradication obtained. Doses smaller than indicated should not be used.
Transient or persistent renal insufficiency may prolong serum levels. After initial loading dose of 1 or 2 g, reduce dose by one half for estimated ClCr of 10-30 mL/min/1.73 m2. When only serum creatinine concentration available, the following formula (based on sex, weight, and age) can approximate ClCr. Serum creatinine should represent a steady state of renal function.
Males: ClCr = [(weight in kg)(140 - age)] / (72 X serum creatinine level in mg/dL)
Females: 0.85 X above value
In patients with severe renal failure (ClCr < 10 mL/min/1.73 m2), those supported by hemodialysis, usual dose of 500 mg, 1 g, or 2 g, is given initially.
Maintenance dose is one fourth of usual initial dose given at usual fixed interval of 6, 8, or 12 h.
For serious or life-threatening infections, supplement maintenance doses with one-eighth of initial dose after each hemodialysis session.
Elderly persons may have diminished renal function. Renal status is a major determinant of dosage in these patients. Serum creatinine may not be an accurate determinant of renal status. Therefore, as with all antibiotics eliminated by kidneys, obtain estimates of ClCr and make appropriate dosage modifications. Insufficient data are available regarding IM administration to pediatric patients or dosing in pediatric patients with renal impairment. Administer IV only to pediatric patients with normal renal function.
Imipenem and cilastatin (Primaxin)
For treatment of multiple organism infections in which other agents do not have wide spectrum coverage or are contraindicated due to potential for toxicity.
Piperacillin and tazobactam sodium (Zosyn)
Antipseudomonal penicillin plus beta-lactamase inhibitor. Inhibits biosynthesis of cell wall mucopeptide and is effective during stage of active multiplication.
Ceftazidime (Ceptaz, Fortaz, Tazicef, Tazidime)
Third-generation cephalosporin with broad-spectrum, gram-negative activity, including pseudomonas; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Arrests bacterial growth by binding to one or more penicillin-binding proteins, which, in turn, inhibit the final transpeptidation step of peptidoglycan synthesis in bacterial cell wall synthesis, thus inhibiting cell wall biosynthesis. The condition of the patient, severity of the infection, and susceptibility of the microorganism should determine the proper dose and route of administration.
Cefotaxime (Claforan)
Third-generation cephalosporin with broad gram-negative spectrum, lower efficacy against gram-positive organisms, and higher efficacy against resistant organisms. Arrests bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins, which in turn inhibits bacterial growth. Used for septicemia and treatment of gynecologic infections caused by susceptible organisms.
Third-generation cephalosporin with gram-negative spectrum. Lower efficacy against gram-positive organisms.
Amikacin (Amikin)
Irreversibly binds to 30S subunit of bacterial ribosomes; blocks recognition step in protein synthesis; causes growth inhibition. For gram-negative bacterial coverage of infections resistant to gentamicin and tobramycin. Effective against Pseudomonas aeruginosa.
Use patient's IBW for dosage calculation. The same principles of drug monitoring for gentamicin apply to amikacin.
Meropenem (Merrem IV)
Bactericidal broad-spectrum carbapenem antibiotic that inhibits cell-wall synthesis. Effective against most gram-positive and gram-negative bacteria. Has slightly increased activity against gram-negatives and slightly decreased activity against staphylococci and streptococci compared with imipenem.
