Antibacterial Antibiotics

Flashcards based on Antibacterial Antibiotics lecture notes.

Antibiotics

Chemicals that inhibit specific bacteria.

Bacteriostatic

Substances that prevent the growth of bacteria.

Bactericidal

Substances that kill bacteria directly.

β-lactam Antibiotics MOA

Inhibits bacterial cell wall synthesis; Bactericidal action

6-aminopenicillanic acid

Β-lactam ring + thiazolidine ring; A component of Penicillins

Mechanism of action of Penicillin

It destroys bacteria by inhibiting the enzyme- transpeptidase responsible for the formation of the cell wall and cross-linking in the bacterial cells

Deterioration of Penicillin

The main cause of deterioration of penicillin is reactivity of the strained lactam ring, particularly to hydrolysis.

Penicillinases

Enzymes that inactivate penicillins

Nature of the acylamino side chain

Determines the extent to which penicillins are plasma protein bound

Penicillin G

Benzylpenicillin; most popular; agent of choice for many infections (but CI in patients with allergy to Pen)

Penicillin V

Has resistance to hydrolysis by gastric juice and its ability to produce uniform concentrations in blood when administered orally

Methicillin Sodium

Not inactivated by penicillinase; Tx of staphylococcal infections caused by strains resistant to other penicillins.

Oxacillin Sodium

Highly resistant to inactivation by penicillinase, resistant to acid hydrolysis so may be administered orally with good effect; Use is restricted to the tx of infections caused by staphylococci resistant to Pen G

Cloxacillin sodium

Almost all other respects, it resembles oxacillin, enhances its activity by enhancing its oral absorption leading to higher plasma levels.

Dicloxacillin Sodium

properties and use are similar to those of cloxacillin sodium

Nafcillin Sodium

Used in infections caused solely by penicillin G- resistant staphylococci or when streptococci are present also; Also effective against pneumococci and group A beta-hemolytic streptococci

Ampicillin

Antibacterial spectrum broader than Pen G, active against Gram (+) susceptible to other penicillins & some gram (-) and enterococci than other penicillins

Bacampicillin Hydrochloride

Prodrug of ampicillin

Amoxicillin

Antibacterial spectrum similar to ampicillin, absorption not impaired by food

Carbenicillin Disodium, Sterile

Broader range of antimicrobial activity than any other known penicillin, must be administered by injection (usually IV)

Carbenicillin Indanyl Sodium

Provides orally active alternative for tx of carbenicillin- sensitive systemic & UTI caused by Pseudomonas sp, Proteus sp, & selected Gram (-) bacilli; Stable in acid

Ticarcillin Disodium, Sterile

Isostere of carbenicillin in w/c phenyl group is replaced by thienyl group; Antibacterial spectrum similar to carbenicillin

Mezlocillin Sodium, Sterile

Antibacterial spectrum similar to carbenicillin & ticarcillin

Piperacillin Sodium, Sterile

Most generally useful of the extended-spectrum acylureidopenicillins, more active than mezlocillin against susceptible strains of gram (-) aerobic bacilli

β-Lactamase Inhibitors

Acts by covalently binding bacterial β-lactamase, allowing β-lactam drugs that would otherwise be destroyed by the β-lactamase to exert their antibacterial effect

Clavulanate Potassium

Antibiotic isolated from Streptomyces clavuligeris; Structurally, it is 1-oxopenam lacking the 6-acylamino side chain of penicillins but possessing a 2-hydroxyethylidene moiety at C-2

Sulbactam

Synthetic penicillin derivative

Tazobactam

Penicillanic acid sulfone that is similar in structure to sulbactam

Carbapenems

Have antibacterial activity similar to penicillins

Thienamycin

β- lactam antibiotic isolated from Streptomyces cattleya

Imipenem

Derived from thienamycin

Meropenem

2nd-generation carbapenem; Tx of infections caused by multiple-resistant bacteria & for serious infections (bacterial meningitis, septicemia, pneumonia, & peritonitis

Biapenem

Newer 2nd-generation carbapenem; Broad-spectrum antibacterial activity (most aerobic gram (-) & (+) bacteria, & anaerobes); Stable to DHP-1 & resistant to most β-lactamases

Cephalosporins

Classified into 1st, 2nd, 3rd & 4th generation agents based on their time of discovery & their antimicrobial properties

Structure of Cephalosporins

Cephalosporin nucleus consists of a β-Lactam ring fused with dihydrothiazine ring ( 7- Aminocephalosporanic acid)

Cephalexin

Tx of UTI; sometimes used for URTI

Cephradine

Only cephalosporin derivative available in both oral & parenteral dosage forms

Cefadroxil

Therapeutic indications similar to Cephalexin & Cephradine

Cefaclor

Tx of non-life-threatening infections caused by H. influenzae particularly strains resistant to ampicillin

Cefprozil

Similar in structure & antibacterial spectrum to cefadroxil

Loracarbef

A carbacephem (contain methylene group in place of 1-sulfur atom)

Cephalothin Sodium

Resistant to penicillinase produced by S. aureus & provides alternative to the use of penicillinase-resistant penicillins for tx of infections caused by such strains.

Cefazolin Sodium, Sterile

More active against gram (-) bacilli but less active against gram (+) cocci than either cephalothin or cephaloridine

Cephapirin Sodium, Sterile

Similar to cephalothin in antimicrobial spectrum & potency

Ceforanide, Sterile

Antimicrobial properties similar to cefamandole ; Has excellent potency against most Enterobacteriaceae family (K. pneumonia, E. coli, P. Mirabilis)

Cefoperazone Sodium, Sterile

Antipseudomonal cephalosporin that resembles piperacillin (chemically & microbiologically)

Cefoxitin Sodium

Effective against strains of gram (-) bacilli (E. coli, K. pneumoniae,etc); Also effective against penicillin-resistant S. aureus & N. gonorrhoeae

Cefotetan Disodium

Similar to cefoxitin in antibacterial spectrum

Cefmetazole Sodium

higher potency against members of Enterobacteriaceae family but lower activity against Bacteroides sp. than cefoxitin

Cefuroxime Sodium

Antibacterial activity resembles that of cefamandole ; Effective in meningitis

Cefpodoxime Proxetil

Tx of upper & lower RTI (pharyngitis, bronchitis, otitis media, CAP); Tx of uncomplicated gonorrhea

Cefixime

Tx of RTI, uncomplicated UTI & gonorrhea caused by β-lactamase-producing bacterial strains

Cefotaxime Sodium

Effective in the tx of meningitis

Ceftizoxime Sodium

Tx of gram (-) or (+) bacterial meningitis

Ceftriaxone Disodium

β- lactamase-resistant cephalosporin; Excellent broad-spectrum antibacterial activity against both gram (+) & (-) organisms

Ceftazidime Sodium

β- lactamase-resistant cephalosporin; Anti-pseudomonal activity; tx of meningitis caused by H. influenzae & N. meningitidis

Ceftibuten

Management of community-acquired respiratory tract, urinary tract & gynecological infections

Cefpirome

First 4th-generation cephalosporin

Cefepime

Similar to Cefpirome; Broad antibacterial spectrum w/ significant activity against both gram (+) & (-) bacteria

Aztreonam Disodium

Active against aerobic gram (-) bacilli including E. coli, K. pneumoniae, P. aeruginosa and the like.

Action of Cephalosporins

Interfere with the cell wall–building ability of bacteria when they divide

Ciprofloxacin Actions

Interferes with DNA replication in susceptible gram- negative bacteria, preventing cell reproduction

Erythromycin Actions

Binds to cell membranes causing a change in protein function and cell death; can be bacteriostatic or bactericidal

Amoxicillin Actions

Inhibits synthesis of the cell wall in susceptible bacteria, causing cell death

Tetracycline Actions

Inhibits protein synthesis in susceptible bacteria, preventing cell replication