ANTIMICROBIAL DRUGS-2

Presented by:

Sarbeel Al Mosddar

Drugs that act Drugs that act on 50S subuniton 50S subunit

ChloramphenicolChloramphenicol

•Antimicrobial Activity :Chloramphenicol has a wide spectrum of antimicrobial activity

bacteriostatic .

Some strains of H influenzae, N meningitidis, and bacteroides chloramphenicol bactericidal ..

It is not active against chlamydia

The drug is commonly used as a topical antimicrobial

•Toxicity:

Gastrointestinal disturbances :

Gray baby syndrome :

Aplastic anemia :

MACROLIDESMACROLIDES

•erythromycin, azithromycin, and clarithromycin )

chlamydia, mycoplasma, legionella, gram-positive cocci ,

and some gram-negative organisms .

Azithrornycin has a similar spectrum of activity but is more active against H influenzae ,

Adverse effects include gastrointestinal irritation )common) , skin rashes ,

CLINDAMYCINCLINDAMYCIN inhibit bacterial protein synthesis via a mechanism

similar to that of the macrolides,

treatment of severe infec tions due to certain anaerobes such as bacteroides.

prophylaxis of endocarditis in valvular disease patients who are penicillin-allergic .

toxicity of clindamycin includes gastrointestinal irrita tion, skin rashes, neutropenia

LINEZOLIDLINEZOLID •drug-resis tant gram-positive cocci, including

strains resistant to beta-lactams and vancomycin • -resistant Enterococcusfaecium .)

Linezolid binds to a unique site on the 50S ribosomal sub unit ,

TelithromycinTelithromycin•Ketolide group

•Similar in structure and action to macrolide•Gram-positive and gram -negative bacteria

•Treatment of community acquired pneumonia

STREPTOGRAMIN SSTREPTOGRAMIN S•Quinupristin-dalfopristin° a

combination of two streptogramins, is bactericidal penicillin-resistant pneumococci ,

methicillin-resistant) and vancomycin-resistant staphylococci

resistant Entero coccus faecium .

Inhibition of nucleic acid Inhibition of nucleic acid synthesissynthesis

•Inhibition of precursorSulfonamides :

active against gram-positive and gram-negative bacteria .nocardia. Shigella.EscherichiaSelective action in blocking folic acid synthesis

TrimethoprimTrimethoprim:: •Trimethoprim is a selective inhibitor of

bacterial dihydrofolate reductase dihydrofolate reductase is four to five orders of magnitude

mammalian enzyme .

Trimethoprim plus sulfamethoxazole :

Inhibition of DNA synthesisInhibition of DNA synthesisQuinolonesBactericidalInhibit DNA GYRASE

ciprofloxacin, ofloxacin, levofloxacin, lomefloxacin, and sparfloxacin .

Fluoroquinolones are effective in the treatment of infections

urogenital and gastrointestinal tracts caused by gram-negative

respiratory tract, skin, and soft tissue infections ,

FlucytosineFlucytosine •pyrimidine antimetabolite

Flucytosine is accumulated in fungal cells by the action of a membrane permease

converted by cytosine deaminase to 5-FU, an inhibitor of

thymidylate synthase

The antifungal spectrum of 5-FC is narrow ;

Cryptococcus neofor roans and possibly systemic candidal infections .

Inhibition of mRNA synthesisInhibition of mRNA synthesis•Rifampin :

bactericidal against M tuberculo sis .The drug inhibits DNA-dependent RNA polymerase

InTP rifampin is always used in combination with other drugs .

prophylaxis against tuberculosis in 1NH-intolerant patients

Alternation of bacterial cell Alternation of bacterial cell membranemembrane•Polymyxins

•Polypeptid•Polymyxin E most clinically useful

•AGAINST gram-negative bacteria•Cationic detergent for phospholipids in plasma

membrane

daptomycindaptomycin•Lipopeptide that disrupt the cell membrane of

gram –positive bacteria

Alternation of fungal cell Alternation of fungal cell membranemembrane

•Amphotericin B :

Amphotericin B is the most important of the drugs in treatment

of systemic mycoses

widest antifungal spectrum the drug of choice for most systemic infections caused by

aspergillus, Candida albicans, cryptococcus ,

bind to ergosterol, a sterol specific to fungal cell membranes, and cause the formation of artificial pores

•Amphotericin B decreases the glomemlar filtration rate

tubular acidosis with magnesium and potassium wasting .

Anemia

Liposomal formulations of amphotericin B have reduced nephrotoxic effects ,

•NystatinOnly used topically for infection caused by Candidad

Azole The azoles used for systemic mycoses

The azoles interfere with fungal cell membrane permeability

hibiting the synthesis of ergosterol .

These drugs act at the step of 14c-demethylation of lanosterol� ,which is catalyzed by a cytochrome P450 isozyme .

Adverse effects of the azoles include vomiting, diarrhea, rash ,

KetoconazoleKetoconazole : :•narrow antifungal spectrum

backup drug for systemic infections caused by certain blastomyces ,

coccidioides, and histoplasma .

commonly for chronic mucocutaneous candidiasis

Fluconazole :

Fluconazole is a drug of choice in esophageal and oropharyngeal can didiasis

Additional drug mechanismsAdditional drug mechanisms•Antibacterial activity

•Isoniazidthe single most important drug used in tuberculosis

inhibition of enzymes required for the synthesis of mycolic acid

Neurotoxic effects are common and include peripheral neuritis, restlessness, muscle twitching, and insomnia .

administration of pyridoxine .

hepatotoxic

MetronidazoleMetronidazole:: activity against protozoa and bacteria .

metronidazole is the drag of choice in trichomoniasis

treatment of in- testinal amebiasis and amebic hepatic abscess .HAVE 2 mechanismes of actionElectron sinkInhibit DNAsynthysis

EthambutolEthambutol•Bacteriostatic

Ethambutol inhibits arabinosyl transferases

involved in the synthesis of arabinogalactan, a component of mycobacterial cell walls .

The only use of ethambutol is in tuberculosis ,The most common adverse effects are dose-dependent visual disturbances ,

Antifungal activityAntifungal activity• Griseofulvin

Treatment of hair and nail infectionBind to tubulin

•Chemoprophylaxis

•probiotics

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