Doxycycline resistance

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. 

The cornerstone of cholera treatment is fluid replacement. Without treatment, the case-fatality rate for severe cholera is approximately 50%. For cholera, rice-based ORT is better than glucose-based ORT because it reduces the number of stools.21 Patients with significant disease should receive a short antibiotic course, 1 to 3 days, to shorten the duration of illness and decrease the number of stools. Doxycycline 300 mg once daily is the drug of choice. Other antibiotics shown to be effective include erythromycin, azithromycin, trimethoprim-sulfamethoxazole, and ciprofloxacin.2 Antibiotic resistance has been documented in V cholerae since 1977.2 Antibiotic prophylaxis is not warranted. 

Alternatives Doxycycline (oral) 1 00 mg daily Greater than or equal to 8 years of age 2 mg/kg (maximum 100 mg) Effective for mefloquine-resistant P. falciparum Start 1-2 days before departure, continue through stay in endemic area, and continue regimen for 4 weeks after returning... 

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. 

Antibiotics shorten the duration of diarrhea, decrease the volume of fluid lost, and shorten the duration of the carrier state (see Table 39-3). A single dose of oral doxycycline is the preferred agent. In children younger than 7 years of age, trimethoprim-sulfamethoxazole, erythromycin, and furazolidone can be used. In areas of high tetracycline resistance, fluoroquinolones are effective. 

In uncomplicated exacerbations, recommended therapy includes a mac-rolide (azithromycin, clarithromycin), second- or third-generation cephalosporin, or doxycycline. Trimethoprim-sulfamethoxazole should not be used because of increasing pneumococcal resistance. Amoxicillin and first-generation cephalosporins are not recommended because of /1-lactamase susceptibility. Erythromycin is not recommended because of insufficient activity against H. influenzae. 

Since patients can rarely be relied upon to take (or be given) medication after fasting, and since itis common experience that doses are omitted more or less frequently the properties of doxycycline make it appear a promising successor to the first generation tetracyclines. This is even more likely since the antibacterial spectrum and activity is at least equal to that of tetracycline, and in the case of certain tetracycline-resistant bacteria doxycycline has (of all derivatives tested) shown the highest activity [35, 41]. 

Malaria (doxycycline only) Prophylaxis of malaria due to Plasmodium falciparum in short-term travelers (less than 4 months) to areas with chloroquine and/or pyrimethamine-sulfadoxine resistant strains. 

Multiply resistant coagulase-negative staphylococci are frequently the cause of postoperative endophtalmitis and require the use of a glycopep-tide (e.g. vancomycin). For topical treatment fusidic acid eye gel, tetracycline or chloramphenicol ointment are available, and can be administered 2 t.d. for 7 days. Trachoma should be treated with an oral macrolide (e.g. a single oral dose of 20 mg/kg azithromycin) or doxycyclin for 3 weeks (for moderate to severe cases). Keratitis needs hourly administration of fortified antibiotic eye drops for 2 weeks. Endophtalmitis needs specialist treatment for 6 weeks. 

COPD exacerbations. Therefore, in exacerbation treatment with antibiotics is justified when the patient has at least two of three features of increased dyspnea, increased sputum volume, and sputum pu-rulence. Antibiotic choice will depend on local experience derived from local bacteriological sensitivity data. Older, less costly compounds such as tetracycline, doxycycline, amoxicillin, erythromycin, cefaclor etc. are often as effective as newer, more expensive ones. If resistant organisms are suspected or when the severity of the patients clinical condition puts them at high-risk of treatment failure, a second or third generation cephalosporin, fluoroquinolone, newer macrolide or broad-spectrum penicillin may be preferred. In cases of recurrent infection prolonged courses of antibiotics continuous or intermittent, may be useful. 

Travelers to areas endemic for chloroquine-resistant disease Mefloquine, doxycycline, or atovaquone/proguanil Excellent... 

Doxycycline Areas with multidrug-resistant P falciparum 100 mg daily... 

Areas without known chloroquine-resistant P falciparum are Central America west of the Panama Canal, Haiti, Dominican Republic, Egypt, and most malarious countries of the Middle East. Malarone or mefloquine are currently recommended for other malarious areas except for border areas of Thailand, where doxycycline is recommended. 

Quinine sulfate is appropriate first-line therapy for uncomplicated falciparum malaria except when the infection was transmitted in an area without documented chloroquine-resistant malaria. Quinine is commonly used with a second drug (most often doxycycline or, in children, clindamycin) to shorten quinine s duration of use (usually to 3 days) and limit toxicity. Quinine is less effective than chloroquine against other human malarias and is more toxic. Therefore, it is not used to treat infections with these parasites. 

Some of the newer tetracycline derivatives such as doxycycline may be used to overcome bacterial strains that are resistant to the traditional drugs.16 Currently, tetracyclines are used to treat specific infections relating to such bacilli as Chlamydia, Rickettsia, and certain spirochetes (see Table 33-5). Tetracyclines may also be used as alternative agents in treating bacterial strains... 

Chloroquine-resistant Quinine Artemisinin derivatives Atovaquone-proguanil Mefloquine Pyrimethamine-sulfadoxine Antibacterials (e.g., clindamycin, doxycycline, sulfamethoxazole, or tetracycline] ... 

A lead compound bearing a ferrocenyl moiety at position N(l) was identified. This derivative is more active than Ciprofloxacin and Doxycycline. The activity is remarkably constant regardless of the level of resistance to CQ of the strains. Contrary to other antibiotics, no delayed-death effect was noted. Isobologram analysis showed that this compound exerts an antagonist effect with the main quinoline-containing antimalarials. In vitro results have to be confirmed in vivo to check the bioavailability of the molecule and its potential interest as a new antimalarial [113],... 

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