Penicillins Aminoglycosides

Infections resistant to other antibiotics (eg, cephalosporins, penicillins, aminoglycosides) have responded to treatment with imipenem. 

Septicemia with granulocytopenia Any Antipseudomonal penicillin + aminoglycoside ceftazidime cefepime imipenem or meropenem consider addition of systemic antifungal therapy if fever persists beyond 5 days of empiric therapy ... 

Pasteurella multocida Aminobenzyl penicillin Aminoglycoside fluoroquinolone... 

Enterobacter, citrobacter, serratia Imipenem, TMP-SMZ, fluoroquinolone Extended-spectrum penicillin, aminoglycoside... 

Norfloxacin (1, R = C2H5, R = H), a typical example, exhibits broad-spectrum activity and is useful in the treatment of upper respiratory tract and urinary infections [7] Lomefloxacin (2), a very recent introduction, is a third-generation product that, given once daily, is especially useful against pathogens resistant to cephalosponns, penicillins, and aminoglycosides [4] Floxacillin (J) is a stable, orally active antibacterial with improved activity over thenonfluonnated product (cloxacillin) [5]... 

Penicillin, ampicillin, nafcillin, ticarcillin, aminoglycosides, and amphotericin B... 

It is important to determine (1) whether the isolate is methicillin-susceptible or methicillin-resistant and (2) whether the patient has a prosthetic valve. For patients with no prosthetic material, methicillin-susceptible staphylococci treatment should consist of a penicillinase-resistant penicillin (e.g., nafcillin or oxacillin) with or without gentamicin, and for methicillin-resistant strains, therapy should consist of vancomycin (see Table 71-4). Combination therapy with aminoglycosides, when used in these patients, typically is given only during the first 3 to 5 days of therapy. In the absence of prosthetic material, some treatment guidelines do not recommend combination therapy against MRSA. However, many clinicians may combine either gentamicin or rifampin with vancomycin if the patient is unresponsive to monotherapy. 

For enterococci, it is imperative to determine species and antibiotic susceptibilities. If the organism is susceptible to penicillin and vancomycin, treatment may consist of high-dose penicillin G, ampicillin, or vancomycin plus gentamicin (see Table 71-6). Treatment length is usually 4 to 6 weeks, with the aminoglycoside used over the entire course. As resistance develops to penicillin, ampicillin and vancomycin remain treatment options. Once the isolate becomes resistant to ampicillin, vancomycin is considered the treatment of choice. 

When used for intraabdominal infection, aminoglycosides should be combined with agents that are effective against the majority of B. fragilis. Clindamycin or metronidazole is the agent of first choice, but others, such as antianaerobic cephalosporins (e.g., cefoxitin, cefotetan, or ceftizoxime), piperacillin, mezlocillin, and combinations of extended-spectrum penicillins... 

Cirrhosis Peritoneal Cefotaxime Regimen based on organism isolated 1. Add clindamycin or metronidazole if anaerobes are suspected 2. Other third-generation cephalosporins, extended-spectrum penicillins, aztreonam, and imipenem as alternatives 3. Aminoglycoside with antipseudomonal penicillin... 

General Imipenem/cilastatin, meropenem, ertapenem, or extended-spectrum penicillins with 3-lactamase inhibitor 1. Aztreonam with clindamycin or metronidazole 2. Ciprofloxacin with metronidazole 3. Aminoglycoside with clindamycin or metronidazole ... 

Spleen Aminoglycoside plus penicillinase-resistant penicillin Alternatives for penicillinase-resistant penicillin are first-generation cephalosporins or vancomycin... 

Cholangitis Aminoglycoside with ampicillin with or without clindamycin or metronidazole Use vancomycin instead of ampicillin if patient is allergic to penicillin... 

These agents are generally effective for susceptible bacteria. The extended-spectrum penicillins are more active against P. aeruginosa and enterococci and are preferred over cephalosporins. They are very useful in renally impaired patients or when an aminoglycoside is to be avoided. 

Only active against gram-negative bacteria, including P. aeruginosa. Generally useful for nosocomial infections when aminoglycosides are to be avoided and in penicillin-susceptible patients. 

Urinary tract Third-generation cephalosporin (ceftriaxone) OR Fluoroquinolone (levofloxacin or ciprofloxacin) Antipseudomonal penicillin OR Antipseudomonal cephalosporin OR Antipseudomonal carbapenem plus aminoglycoside... 

Pseudomonas Cephtazidime, cefepime, imipenem, aztreonatn, ciprofloxacin, aminoglycoside, and extended-spectrum penicillin... 

The combination of penicillin G or ampicillin with an aminoglycoside results in a bactericidal effect. Patients should be treated for 2 to 3 weeks after defervescence to prevent the possibility of relapse. Combination therapy is given for at least 10 days with the remainder completed with penicillin G or ampicillin alone. 

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