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ePaper created 2016-11-22, 09:52:12 | version 1.38.0
antibiotics CE article | 11 roots 4 2016 2. Clindamycin is the antibiotic of choice for patients allergic to penicillins. 3. While amoxicillin and augmentin (amoxicillin plus clavulanate) demonstrated a higher antibacterial effectiveness than Pen-V-K, due to the broader antibacterial spectrum of amoxicillin and the in- creased cost of augmentin, the authors recom- mended that amoxicillin/augmentin be reserved forunresolvedinfectionsandpatientswhoareim- munocompromised. 4. Metronidazol demonstrated the greatest amount of bacterial resistance and is only effective against anaerobes. Therefore, it should not be used alone for the treatment of endodontic infections.14 Myth No. 4: Antibiotics increase the host’s defense to infection Theincreasedprevalenceinorganandtissuetrans- plants, resulting in patients with compromised im- mune systems, has heightened the interest in the po- tential effects of antimicrobial drugs on the host’s resistancetoinfection.15 Invivoandinvitrostudiesare highly variable and sometimes contradictory. How- ever,thefollowingconsiderationsappearvalid:1)An- tibiotics that can penetrate into the mammalian cell (erythromycin, tetracycline, clindamycin and metro- nidazole) are more likely to affect the host defenses than those that cannot (beta-lactams); 2) Tetracy- clines may suppresswhitecellchemotaxis; 3) Most antibiotics (except tetracycline) do not depress phago- cytosis; and 4) T- and B-lymphocyte transformation maybedepressedbytetracyclines.Thegreatestpoten- tialharmtothehostdefensesmayresultfromantibi- otics that easily penetrate into the mammalian cell andtheleastharmisobservedwithbactericidal,non- penetrating agents (penicillins and cephalosporins). Myth No. 5: Multiple antibiotics are superior to a single antibiotic It is often assumed that a combination of antibiot- ics is superior to a single carefully chosen antibacte- rial agent. When the purported benefits of antibiotic combinations are weighed against the possible con- sequences to the host as well as to the bacterial envi- ronment, this assumption is not always reality. The usual sequela to combined antibiotic therapy results inagreaterselectivepressureonthemicrobialpopu- lation to develop drug resistance. The greater the an- tibacterial spectrum of the antimicrobials used, the greater the number of drug-resistant microorgan- isms that develop, and the more difficult it is to treat a resulting superinfection. The primary clinical indi- cationforcombinedantimicrobialtherapyisasevere infection in which the offending organism(s) is un- known and major consequences may ensue if anti biotic therapy is not instituted immediately before culture and sensitivity tests are available.3 Myth No. 6: Bactericidal agents are always superior to bacteriostatic agents Bactericidal agents are required for patients with impaired host defenses.3 However, bacteriostatic agents are usually satisfactory when the host’s de- fenses against infections are unimpaired. Post anti bioticeffects(PAEs—persistentsuppressionofbacte- rial growth after previous exposure to antibiotics) are morepersistentandreliablewithbacteriostaticagents (erythromycin, clindamycin) than with bactericidal agents (beta-lacatamase) because the clinical effects of bacteriostatic agents are less dose-dependent. Myth No. 7: Antibiotic dosages, dosing intervals and duration of therapy are established for most infections After more than 80 years of antibiotic usage, the proper dosages, dosing intervals and duration of therapyareessentiallyunknownformostspecificin- fections.3 Infectious diseases are associated with a high number of variables that affect treatment out- come (microbial characteristics and drug sensitivity, diverse resistance mechanisms, tissue barriers to an- tibioticdiffusion,andtheintegrityandactivityofthe host’s defense mechanisms). However, basic princi- plesareavailabletoguidethedentalhealthcarepro- vider in establishing proper dosages, dosing intervals and duration of therapy once the microbial patho- gen(s) is suspected or identified and a rational choice of antimicrobial agent is made. The following principles of antibiotic dosing are adapted from Dr Thomas J. Pallasch3 : 1. The current recommendation is to employ an antimicrobial on an intensive basis with vigorous dosage for as short a period of time as the clinical situation permits. The major factor in the clinical success of most antimicrobial agents is the height of the serumconcentration ofthe drugand there- sulting amount in the infected tissue(s). Also im- Primary Reasons for Revision of Infective Endocarditis Guidelines 1.IE is much more likely to result from frequent exposure to random bacteremias associated with daily activities than from bacteremias caused by a dental, GI tract or GU tract procedure. 2.Prophylaxis may prevent an exceedingly small number of cases of IE,if any, in individuals who undergo a dental,GI tract or GU tract procedure. 3.The risk of antibiotic-associated adverse events exceeds the benefit,if any, from prophylactic antibiotic therapy. 4.Maintenance of optimal oral health and hygiene may reduce the incidence of bacteremia from daily activities and is more important than prophylactic antibiotics for a dental procedure to reduce the risk of IE. Table 1 42016