Dental Antibiotic Lecture With Voice PDF

Antibiotic therapy Vaccines for healthcare worker  Key points Introduction Choice of the proper antibiotic Antimicrobial combinations Choice of the route and efficacy assessment Sir A. Fleming: discoverer of Penicillin Noble prize 1945 ...

Antibiotic therapy Vaccines for healthcare worker  Key points Introduction Choice of the proper antibiotic Antimicrobial combinations Choice of the route and efficacy assessment Sir A. Fleming: discoverer of Penicillin Noble prize 1945  Antibiotics PCNs Cephalosporins Carbapenem Monobactams Glycopeptide Aminoglycoside Fluroquinolone  PCN PCN G PCN V Amoxicillin Cloxacillin Oxacillin Ampicillin Piperacillin Methicillin  Choice of the proper agent 1) Identification of the organism 2) Antimicrobial susceptibility 3) The narrowest effective spectrum 4) Host factors (Allergy, Age, renal and liver, site of infection, pregnancy, metabolic abnormalities)  Identification of the organism Gram stain (CSF, Pleural, synovial, peritoneal, urine, sputum) ELISA / latex agglutination PCR CULTURE (best if before Abx) Bacteriologic statistics (the application of knowledge of the organisms most likely to cause infection in a given clinical sitting)  Antimicrobial susceptibility Disk diffusion method Epsilometer (E-test) Minimum inhibitory conc. (MIC) Minimum bactercidal conc. (MBC) Specialized testing for: fastidious organisms (obligate anaerobes), Haemophilus spp, pneumococci, MRSA Resistance mechanism of the bacteria: eg: Staph. aureus, E. coli, Enterbacter …..  Pharmacodynamic profile Area under the curve / time curve to MIC (AUC / MIC) Maximal serum conc. / MIC (C max / MIC) Time during dosing interval that plasma conc. exceed the MIC (t / MIC)  Conc. & Time dependent dosing Conc. dependent (FQ, Ag) 🡪 increase in conc leads to a more rapid rate of bacterial death (i.e. large dose at long intervals) Time dependent (β-lactams, vancomycin) 🡪reduction in bacterial density is proportional to the time that the conc. exceeds MIC (i.e. sufficient dose at appropriate intervals to keep conc. above MIC)  Organism A Concentration Organism B Time Organism C A : resistant; B : moderately susceptible; C very susceptible  Resistance selection days Antibiotic X Antibiotic X  Published data Manuals eg: Sanford’s Medical letter on drugs and therapeutics (nb: use this information within its context)  Host factors Previous history of adverse reactions Neutrophil function 🡪 neutropenic are treated aggressively CLL, Multiple Myeloma, asplenia 🡪 treated empirically  Age Renal function (impaired physiologic function) Absorption Tetracyclines INH hepatotoxicity Nephrotoxicity Ag and cochlear toxicity  Genetic / metabolic Hemolysis in G6PD deficiency DM : sulfa drugs can potentiate the sulfonylurea hypoglycemic agents - Dextrose load - Poor IM absorption (use IV route)  Pregnancy Safe : PCN, cephalosporin, erythromycin Dangerous: tetracyclines (hepatic toxicity, dental discoloration) ? metronidazole FQ 🡪 Contrindicated ?? rifampin, Ag, azithromyccin, clindamycin, imipenem,vancomycin, TMP Abx dose needs to be increased?  Renal and liver fx Vancomycin & Aminoglycosides  Site of infection Optimal therapy requires concentrations > MIC at the site of infection Meningitis Endocarditis Osteomylitis Chronic prostatitis Intraocular infections Abscesses Foreign body UTI  Immune system Abx can cause immune suppression esp. in the immunosuppressed patients Suppress monocyte transformation, phagocytosis, chemotaxis, antibody production  Combinations Some physicians use combinations for the sense of security 🡪 deleterious effects Indications: 1) prevention of emergence of resistant bacteria : TB, staph endocarditis 2) polymicrobial infections : abd. sepsis 3) initial therapy: eg: Ag + piperacillin 4)Synergism:…  Synergism For resistant organisms Limited data to support their benefit e.g.: PCN + Ag 🡪 Enterococcal endocarditis Oxacillin + Ag 🡪 Staph. endocarditis Anti-pseudomonal β- lactam + Ag 🡪 Pseudomonas bacteremia Impaired host  Antagonism Too many in vitro reports Clinically was seen in : PCN + tetracyclines 2 β-lactams 🡪 induce β lactamases More important in immunosuppressed pts  Adverse effects 5% of pts will have a side effect Combinations 🡪 more cost, more adverse effects  Anaphylaxis Beta lactams are the most common ABx to cause anaphylaxis PCN risk of anaphylaxis: 0.01% Death occurs in 1 / 100,000 courses 10 - 20% of pts who claim to have an allergy to PCN are truly allergic 50% of pts with a positive skin test: reaction  Anaphylaxis PCN cross reaction with Cephalosporins Minimum cross reaction with carbapenem ≈ 1% No cross reaction with Aztreonam (except ceftazidime)  Route Oral 🡪 stable , mild infection (reliable pts) IV 🡪 serious infections (sepsis) + DM  Monitoring the response Clinically Drug levels Lab tests  Cost If all other factors are equal, the least expensive drug should be chosen  Needle stick Risk of transmission - Hepatitis B virus 30% - Hepatitis C virus 3% - HIV 0.3%  HBV Vaccine recommendations HB vaccine offered for all HCW – Required in US (1991) – Human rights issues (what if they refused ??) Check response after 1 month – Responders: ….. 10 IU/l – Non responders………. < 10 IU/l  HBV vaccine Does not transmit the virus 3 shots at 0, 1, 6 months The series is administered once A booster shot can be given in times of outbreak conditions If you are exposed to HBV immediate vaccination is extremely helpful  HBV vaccine (cont) You do not need to accept the vaccine You can decline it and sign a declination form If you are exposed to HBV or changed your mind, you can still receive it Your employer might not offer you the vaccine if: – You are vaccinated – Have Antibodies – Contraindicated in your case HBV (cont)  Response or no ??? High risk practice True non response vs. Waning Ab levels One boost to differentiate – Non response: < 10 IU/l – Responders: > 10 IU/l NEJM Dec 2004  To boost or not to boost ?? Currently, there is no proof that booster injections are indicated for the first two decades after successful immunization After 3rd decade: ???? Studies are needed J clini Virology 2003  Influenza vaccine Annually In the fall season – even if late 2 strains of A + 1 strain of B No protection against other Flu like illnesses like – RSV – Para influenza – Adenovirus  Influenza vaccine Weak or no association with Guillain Barre syndrome – 1 / million Contraindication – Previous GB syndrome – ? Egg allergy – Allergic reaction to any component  Prevention - Rubella Rubella IgG + Immune _ Non-Immune MMR (avoid pregnancy x 2 m) 2 _ _ month Check titers Booster Inform patient s + Immune  Rubella-risk Risk of congenital infection ❑ 1 + 2 month: 90% ❑ 3rd month 50% ❑ Termination of pregnancy is usually recommended in Western countries ❑ > 16 weeks negligible ❑ 12 – 16 weeks: deafness can occur  Congenital rubella syndrome: growth retardation; malformations of the heart, eyes, or brain; deafness; and liver, spleen, and bone marrow problems.  Prevention - Varicella Varicella – History of chicken pox: … immune – Positive titers …....... immune – Absent titers: not immune Give vaccine: 2 doses, 2 months apart – Postpone pregnancy 2 m after the second dose  Tetanus - Diphtheria vaccine Once every ten years Toxoid vaccine  Peneumococcal vaccine Indicated for all immunocompromised adults > 65 years 1 or 2 doses ‫ﺷﻛرا‬