Augmentin :: Multiple pharmacies comparison.

Beta-lactam antibiotics include penicillins, cephalosporins and related compounds. As a group, these drugs are active against many gram-positive, gram-negative and anaerobic organisms. Information based on “expert opinion” and antimicrobial susceptibility testing supports certain antibiotic choices for the treatment of common infections, but less evidence-based literature is available to guide treatment decisions. Evidence in the literature supports the selection of amoxicillin as first-line antibiotic therapy for acute otitis media. Alternative drugs, such as amoxicillin-clavulanate, trimethoprim-sulfamethoxazole and cefuroxime axetil, can be used to treat resistant infections. Penicillin V remains the drug of choice for the treatment of pharyngitis caused by group A streptococci. Inexpensive narrow-spectrum drugs such as amoxicillin or trimethoprim-sulfamethoxazole are first-line therapy for sinusitis. Animal and human bites can be treated most effectively with amoxicillin-clavulanate. For most outpatient procedures, amoxicillin is the preferred agent for bacterial endocarditis prophylaxis. Beta-lactam antibiotics are usually not the first choice for empiric outpatient treatment of community-acquired pneumonia. Based on the literature, the role of beta-lactam antibiotics in the treatment of bronchitis, skin infections and urinary tract infections remains unclear. (Am Fam Physician 2000;62:611-20.)

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Long Island Technology Briefs: September 30, 2005

Beta-lactam antibiotics, which are named for the beta-lactam ring in their chemical structure,(1) include the penicillins, cephalosporins and related compounds. These agents are active against many gram-positive, gram-negative and anaerobic organisms. The beta-lactam antibiotics exert their effect by interfering with the structural crosslinking of peptidoglycans in bacterial cell walls. Because many of these drugs are well absorbed after oral administration, they are clinically useful in the outpatient setting.
Resistance to Beta-Lactam Antibiotics
Bacterial resistance against beta-lactam antibiotics is increasing at a significant rate and has become a common problem in primary care medicine. There are several mechanisms of antimicrobial resistance to beta-lactam antibiotics.(1-3) One important mechanism is the production of beta-lactamases, which are enzymes that cleave the beta-lactam ring.(4) Beta-lactamase activity can occur in gram-positive organisms (Staphylococcus aureus and Staphylococcus epidermidis); gram-negative organisms (Haemophilus influenzae, Neisseria gonorrhoeae, Moraxella [formerly Branhamella] catarrhalis, Escherichia coli, and Proteus, Serratia, Pseudomonas and Klebsiella species); and anaerobic organisms (Bacteroides species).
The newer beta-lactam antibiotics can be highly effective in combating infections caused by beta-lactamase-producing organisms. When used alone, beta-lactamase inhibitors (clavulanate, sulbactam and tazobactam) have weak intrinsic antibacterial activity, but their effectiveness increases when they are combined with a beta-lactam antibiotic (e.g., amoxicillin-clavulanate [Augmentin]).
Orally administered beta-lactam antibiotics are divided into classes based on their antimicrobial spectrum(5) (Table 1).
Oral Penicillins
The orally administered penicillins include natural penicillins, penicillinase-resistant penicillins, aminopenicillins, beta-lactam- beta-lactamase inhibitor combinations and antipseudomonal penicillins.(6)
The antibiotic properties of Penicillium mold were first noted by Fleming in 1928.(1) Penicillins first became available commercially in the mid-1940s, and they remain one of the most important classes of antimicrobial agents. Despite the development of bacterial resistance, which was noted shortly after the penicillins were introduced, these drugs are still widely used, and new penicillin derivatives are being developed.
NATURAL PENICILLINS
Penicillin V, the potassium salt of phenoxymethyl penicillin, is well absorbed orally, and peak serum levels are achieved within 60 minutes. Penicillin G is not as well absorbed and is therefore less useful for oral therapy. Penicillin V is indicated for the treatment of mild gram-positive infections of the throat, respiratory tract and soft tissues. This natural penicillin is still the drug of choice for the treatment of group A streptococcal pharyngitis in patients who are not allergic to penicillin.(5) Penicillin V is also useful for anaerobic coverage in patients with oral cavity infections.
PENICILLINASE-RESISTANT PENICILLINS
Penicillinase-resistant penicillins were developed because of the increasing resistance of staphylococci to natural penicillins. These chemically modified penicillins have a side chain that inhibits the action of penicillinase.(6)
The penicillinase-resistant penicillins are active against Streptococcus and Staphylococcus species, but they are not active against methicillin-resistant S. aureus, which is becoming an increasingly common organism.(7) These drugs also do not have activity against gram-negative organisms.