Clindamycin-resistant

Of the latter four agents, clindamycin has the most data supporting its use. However, the clinician must be aware of inducible clindamycin resistance. For CA-MRSA isolates determined to be resistant to erythromycin but sensitive to clindamycin, an additional laboratory analysis, known as the erythromycin-clindamycin D-zone test, is conducted to assess for inducible clindamycin resistance.15 Isolates for which the D-zone test indicates inducible resistance should not be treated with clindamycin. 

CCA-MRSA isolates resistant to erythromycin should be evaluated for inducible clindamycin resistance. 

CA-MRSA isolates resistant to erythromycin should be evaluated for inducible clindamycin resistance. cLimited clinical data exist for the treatment of MRSA infections. 

Restricting the use of clindamycin has been successful in terminating outbreaks of C. difficile diarrhea associated with its use (29). Between 1989 and 1992, outbreaks of diarrhea due to a clindamycin-resistant strain of C. difficile occurred in different parts of the USA. Resistance was mediated by the ermB gene. The use of chndamycin was a specific risk factor for diarrhea due to this strain (30). 

Ohm-Smith MJ, Sweet RL, Hadley WK. Occurrence of clindamycin-resistant anaerobic bacteria isolated from cultures taken following chndamycin therapy. Antimicrob Agents Chemother 1986 30(1) 11-14. 

Dalmau D, Cayouette M, Lamothe F, et al. Clindamycin resistance in Bacteroides fragilis group Association with hospital-acquired infection. Clin Infect Dis 1997 24 874-877. 

Clindamycin binds exclusively to the 50S subunit of bacterial ribosomes and suppresses protein synthesis. Although clindamycin, erythromycin, and chloramphenicol are not structurally related, they act at sites in close proximity, and binding by one of these antibiotics to the ribosome may inhibit the interaction of the others. There are no clinical indications for the concurrent use of these antibiotics. Macrolide resistance due to ribosomal methylation by encoded enzymes also may produce resistance to clindamycin. However, because cUndamycin does not induce the methylase, there is cross-resistance only if the enzyme is produced con-stitutively. Clindamycin is not a substrate for macrolide efflux pumps thus, strains that are resistant to macrolides by this mechanism are susceptible to clindamycin. Altered metabolism occasionally causes clindamycin resistance. 

Hachler, H., Berger-Bachi, B., and Kayser, F. H. (1987). Genetic characterization of a Clostridium difficile erythromycin-clindamycin resistance determinant that is transferable to Staphylococcus aureus. Antimicrob. Agents Chemother. 31, 1039-1045. 

Cross-resistance between lincomycin and clindamycin is complete (64), and co-resistances of lincomycin also apply to clindamycin. However, the inactivation of clindamycin by clinical isolates of Staphylococcus haemolyticus and Staphylococcus aureus is caused by adenylylation at the 4-position to form clindamycin 4-(5 -adenylate) [29752-38-3] (7) in contrast to the lincomycin 3-(5 -adenylate) [117785-83-8] (8) that forms (26). 

Ribosomal Protein Synthesis Inhibitors. Figure 5 Nucleotides at the binding sites of chloramphenicol, erythromycin and clindamycin at the peptidyl transferase center. The nucleotides that are within 4.4 A of the antibiotics chloramphenicol, erythromycin and clindamycin in 50S-antibiotic complexes are indicated with the letters C, E, and L, respectively, on the secondary structure of the peptidyl transferase loop region of 23S rRNA (the sequence shown is that of E. coll). The sites of drug resistance in one or more peptidyl transferase antibiotics due to base changes (solid circles) and lack of modification (solid square) are indicated. Nucleotides that display altered chemical reactivity in the presence of one or more peptidyl transferase antibiotics are boxed. 

To prevent development of resistance and promote synergy, inhaled tobramycin or colistin is usually added to an oral fluoroquinolone for P. aeruginosa coverage.1,3 Methicillin-sensitive S. aureus (MSSA) may be treated with oral amoxiciUin-clavulanic acid, dicloxacillin, first- or second-generation cephalosporins, trimethoprim-sulfamethoxazole, or clindamycin, depending on sensitivity. Likewise, methiciUin-resistant S. aureus (MRSA) may be treated with oral trimethoprim-sulfamethoxazole, clindamycin, minocycline, or linezolid. H. influenzae often produces... 

Adverse effects are generally mild and include dryness, erythema, and itching.18 Although rare and seen most often with oral therapy, pseudomembranous colitis can occur with the use of topical clindamycin.19 As with any antibacterial agent, the possibility of resistance exists with the use of topical erythromycin. However, co-administration of erythromycin and benzoyl peroxide has been shown to decrease the incidence of resistance, as well as to improve symptoms of mild to moderate inflammatory acne.20... 

Although tetracycline, doxycycline, and minocycline are the most commonly prescribed oral antibiotics for acne, erythromycin and clindamycin are appropriate second-line agents for use when patients cannot tolerate or have developed resistance to tetracycline or its derivatives.3 See Table 62-3 for antibiotic dosing guidelines. 

Although their effectiveness is similar to the tetracyclines, the use of erythromycin and clindamycin is often limited due to their potential adverse outcomes. Erythromycin has treatment failure due to resistance and a high incidence of gastrointestinal intolerance, while clindamycin causes diarrhea and carries a risk of developing pseudomembranous colitis with long-term use.3,8... 

Broad-spectrum antibiotic cefotaxime or ceftriaxone (clindamycin for cephalosporin allergy) vancomycin for staphylococcal and resistant pneumococcal organisms... 

Cefazolin or cefuroxime are appropriate for prophylaxis in cardiothoracic and vascular surgeries. In the case of 3-lactam allergy, vancomycin or clindamycin are advised. Debate exists on the duration of antimicrobial prophylaxis. The National Surgical Infection Prevention Project cites data that extending prophylaxis beyond 24 hours does not decrease SSI rates and may increase bacterial resistance.1 American Society of Health-System Pharmacists guidelines from 1999 allow for the continuation of prophylaxis for up to 72 hours.22 Duration of therapy should be based on patient factors and risk of development of an SSI. SSIs are rare after cardiothoracic operations, but the potentially devastating consequences lead some clinicians to support longer periods of prophylaxis. 

The answer is c. (Hardman, pp 996-997r 1145—1146. Ka tzung, p 8455 Metronidazole is often used to treat antibiotic-associated enterocolitis, especially when caused by C difficile. Vancomycin is no longer preferred because it induces selection of resistant staphylococci. Clindamycin is also associated with C difficile colitis, but in another way a higher percentage of patients taking this over other antibiotics develop antibiotic-associated enterocolitis. 

The currently recommended regimen for group B Streptococcus disease is penicillin G, 5 million units IV, followed by 2.5 million units IV every 4 hours until delivery. Alternatives include ampicillin, 2 g IV, followed by 1 g IV every 4 hours cefazolin 2 g IV, followed by 1 g every 8 hours clindamycin, 900 mg IV every 8 hours or erythromycin, 500 mg IV every 6 hours. In women who are penicillin-allergic, and in whom sensitivity testing shows the organism to be resistant to clindamycin and erythromycin, vancomycin 1 g IV every 12 hours until delivery can be used. 

FCC,b c trimethoprim-sulfamethoxazole, clindamycin ampidllin-sulbadam, or amoxidllinresistant Vancomycin (gentamicin or rifampin)... 

Mild-moderate infections can generally be treated with oral agents (didoxacillin, cephalexin, clindamycin) unless resistance is high in the community. 

Serious infections should be treated intravenously with a penicillinase-resistant penicillin (nafcillin) or first-generation cephalosporin (cefazolin). Patients with penicillin allergies should be treated with vancomycin or clindamycin. 

Penicillinase-resistant penicillins, first-generation cephalosporins, macrolides, and clindamycin should not be used for treatment because of their poor activity against Pasteurella multocida. 

In penicillin-allergic patients, oral or parenteral clindamycin may be used. Alternatively, a first-generation cephalosporin such as cefazolin (1 to 2 g IV every 6 to 8 hours) may be used cautiously for patients who have not experienced immediate or anaphylactic penicillin reactions and are penicillin skin test negative. In severe cases in which cephalosporins cannot be used because of documented methicillin resistance or severe allergic reactions to /1-lactam antibiotics, IV vancomycin should be administered. 

Pharmacology Lincomycin and clindamycin, known collectively as lincosamides, bind exclusively to the 50 S subunit of bacterial ribosomes and suppress protein synthesis. Cross-resistance has been demonstrated between these 2 agents. Clindamycin is preferred because it is better absorbed and more potent. Pharmacokinetics Administration with food markedly impairs lincomycin (but not clindamycin) oral absorption. 

Anaerobic infections Treaimeni of serious infections caused by susceptible anaerobic bacteria. Effective in Bacteroides fragilis infections resistant to clindamycin, chloramphenicol, and penicillin. 

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