Minocycline resistance

Thiatetracyclines contain a sulphur atom at position 6 in the molecule. One derivative, thiacycline, is more active than minocycline against tetracycline-resistant bacteria. Despite toxicity problems affecting its possible clinical use, thiacycline could be the starting point in the development of a new range of important tetracycline-type antibiotics. 

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... 

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. 

Doxycycline is commonly used for moderate to severe acne vulgaris. It is more effective and produces less resistance than tetracycline. The initial dose is 100 or 200 mg daily, followed by 50 mg daily as a maintenance dose after improvement is seen. Doxycycline maybe given with food, but it is more effective when taken 30 minutes before meals. / Minocycline is also commonly used for moderate to severe acne vulgaris. It is more effective than tetracycline. It is dosed similar to doxycycline (100 mg/day or 50 mg twice daily) and on an indefinite basis in selected patients. Minocycline has the most reported adverse effects of the tetracyclines, some of which may be serious. 

Minocycline is an effective alternative to rifampin for eradication of meningococci, including sulfonamide-resistant strains, from the nasopharynx. However, the high incidence of dose-related vestibular side effects renders it less acceptable. Although minocychne has good in vitro activity against Nocardia spp., further studies are necessary to confirm its clinical efficacy. 

Minocycline, 200 mg orally daily for 5 days, can eradicate the meningococcal carrier state, but because of side effects and resistance of many meningococcal strains, rifampin is preferred. Demeclocycline inhibits the action of antidiuretic hormone in the renal tubule and has been used in the treatment of inappropriate secretion of antidiuretic hormone or similar peptides by certain tumors (see Chapter 15). 

Methicillin-resistant Vancomycin TMP-SMZ,1 minocycline, linezolid, daptomycin, tigecycline... 

Tetracyclines are recommended as first-line treatment. When tetracyclines are not tolerated or contraindicated, erythromycin is an alternative. However erythromycin has problems with resistance and gastrointestinal adverse effects. If compliance is a problem, either doxycycline or lymecycline may be prescribed (can be taken once daily with food). Minocycline is second-line treatment (e.g. if oral antibiotic has failed). 

Generally very resistant to all antimicrobials check sensitivities to ceftazidime, ticarcillin[Pg.382]

Systemic or topical antimicrobial therapy (tetracycline, minocycline, erythromycin, at low dose) is used over months (response begins after 2 months). Bacterial resistance is not a problem benefit is due to suppression of bacterial lipolysis of sebum, which generates inflammatory fatty acids. Raised intracranial pressure with loss of vision has occurred with tetracycline used thus. 

Raad I, Hachem R, Hanna H, Girgawy E, Rolston K, Whimbey E, Husni R, Bodey G. Treatment of vancomycin-resistant enterococcal infections in the immunocompromised host quinupristin-dalfopristin in combination with minocycline. Antimicrob Agents Chemother 2001 45(ll) 3202-4. 

Various antibiotics have been investigated for their ability to eradicate mycoplasma from cell lines. Historically the antibiotics of choice were either minocycline or tiamulin. However, many cell culture mycoplasmas are now resistant to these antibiotics. Today the most effective are the quinalone antibiotics ciprofloxacin (Mowles, 1988) and MRA (see Table 1.9.3). 

Tetracycline was discovered after a team of workers examined 100000 soil samples from around the world. Tetracycline derivatives include chlor-tetracycline, oxytetracycline, doxycycline and minocycline. The tetracyclines have a broad spectrum of activity they are effective against Grampositive and Gram-negative bacteria, some anaerobes. Chlamydia, Mycoplasma, Ehrlichia and Rickettsia spp. and some protozoa. Their activity against staphylococci is usually limited and they are not active against enterococci. E. coli, Klebsiella, Proteus and Pseudomonas spp. are usually resistant. Doxycycline and minocycline are usually more active in vitro than the other tetracyclines. Differences in the clinical efficacy of the tetracyclines can be attributed to differences in the absorption, distribution and excretion of the individual drugs rather than to differences in bacterial susceptibility. 

Fig. 13.6 Structural modifications at the 9 position of the tetracycline antibiotic minocycline conferring increased stability against resistance mechanisms.

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