Inhibitors of Cell Wall SynthesisPenicillin

Natural penicillinsSemisynthetic penicillinsExtended-spectrum penicillins

PenicillinsLow toxicityEffective derivatives created from

manipulating drug’s basic molecular structure

Kills bacteria by preventing them from forming the rigid cell wall

Because human cells do not have cell walls, they are not affected

Therapeutic Uses of PenicillinsAbscessesBeta-hemolytic streptococcusMeningitisOtitis mediaPneumoniaRespiratory infectionsTooth and gum infectionsVenereal diseases (syphilis and gonorrhea)Endocarditis due to streptococci

Penicillins’ Side EffectsDiarrheaAllergies in 7% to 10% of population

Penicillins’ Dispensing IssuesTake on an empty stomach

Food slows absorptionAcids in fruit juices or colas could deactivate

the drug

The Structure of Penicillins

The Structure of Penicillins

Retention of Penicillin G

The Effect of Penicillinase on Penicillins

-b Lactam AntibioticsPenicillin

Penicilinase-resistant penicillins

Penicillins + -lactamase inhibitors

CarbapenemsSubstitute a C for a

S, add a double bond

MonobactamSingle ring

Inhibitors of Cell Wall SynthesisCephalosporins

First-generation: Narrow spectrum, gram-positive

Second-generation: Extended spectrum includes gram-negative

Third-generation: Includes pseudomonads; injected

Fourth-generation: Oral

First-generation Similar to penicillinase-resistant penicillins with greater gram-

negative coverage Used for

community-acquired infections mild to moderate infections

Second-generation Increased activity, especially against Haemophilus influenzae Used for

Otitis media in children Respiratory infections UTIs

Third-generation Active against a wide spectrum of gram-negative organisms Long half-life, so once-a-day dosing for some Used for

Ambulatory patients Children (dosing before or after school)

Inhibitors of Cell Wall SynthesisPolypeptide antibiotics

Bacitracin Topical application Against gram-positives

Vancomycin Glycopeptide Important "last line" against antibiotic-resistant

S. aureus

Comparison of Cephalosporin and Penicillin

The Inhibition of Protein Synthesis by Antibiotics

Inhibitors of Protein SynthesisChloramphenicol

Broad spectrum Binds 50S subunit; inhibits peptide bond formation

Inhibitors of Protein SynthesisAminoglycosides

Streptomycin, neomycin, gentamycin Broad spectrum

Changes shape of 30S subunit

Inhibitors of Protein Synthesis

Inhibitors of Protein SynthesisStreptogramins

Gram-positives Binds 50S subunit; inhibits translation

Inhibitors of Protein Synthesis

Inhibitors of Protein SynthesisOxazolidinones

Linezolid Gram-positives

Binds 50S subunit; prevents formation of 70S ribosome

Inhibitors of Nucleic Acid SynthesisRifamycin

Inhibits RNA synthesisAntituberculosis

Quinolones and fluoroquinolonesNalidixic acid: Urinary infectionsCiprofloxacinInhibits DNA gyraseUrinary tract infections

QuinolonesStrong, rapid bactericidal action against most

gram-negative and many gram-positive bacteriaAntagonize the enzyme responsible for coiling

and replicating DNA, causing DNA breakage and cell death

Quinolones’ Dispensing IssuesNot to be given with theophyllineAntacids interfere with absorptionAvoid exposure to sun

Therapeutic Uses of QuinolonesBone and joint infections caused by gram-

negative organismsInfectious diarrheaOphthalmic infectionsSome sexually transmitted diseasesUpper respiratory infectionsUTIs

Quinolones’ Side EffectsPrimarily gastrointestinal, with nausea and

vomitingDizzinessUnpleasant tasteCan cause joint problems such as swelling

and malformationsPatients taking them have a tendency to

injure tendons

Rifamycinany of a family of antibiotics biosynthesized

by a strain of Streptomyces mediterranei, effective against a broad spectrum of bacteria, including gram-positive cocci, some gram-negative bacilli, and Mycobacterium tuberculosis and certain other mycobacteria; used for the treatment of tuberculosis and the prophylaxis of meningococcal infections.

Adverse reactions

CNS: ataxia, confusion, drowsiness, fatigue, headache, asthenia, psychosis, generalized numbness

EENT: conjunctivitis; discolored tears, saliva, and sputum GI: nausea, vomiting, diarrhea, abdominal cramps, dyspepsia,

epigastric distress, flatulence, discolored feces, anorexia, sore mouth and tongue, pseudomembranous colitis

GU: discolored urine Hematologic: eosinophilia, transient leukopenia , hemolytic

anemia, hemolysis, disseminated intravascular coagulation (DIC), thrombocytopenia

Hepatic: jaundice Metabolic: hyperuricemia Musculoskeletal: myalgia, joint pain Respiratory: dyspnea, wheezing Skin: flushing, rash, pruritus, discolored sweat, erythema

multiforme, toxic epidermal necrolysis, Stevens-Johnson syndrome Other: flulike symptoms, hypersensitivity reactions including vasculitis

prophylaxis refers to medical or public health measures taken in order to prevent disease or health problems, rather than to treat or cure an existing condition. Prophylaxis is also a way to stem an outbreak of disease, or minimize the symptoms of someone who has been exposed to a disease or virus.