This document discusses several broad-spectrum antibiotics and their uses, including tetracyclines, chloramphenicols, and nitrofurantoin. It provides information on the pharmacokinetics, antimicrobial activity and mechanisms, therapeutic uses, and adverse reactions of each antibiotic. Tetracyclines are described as having a broad spectrum of activity against gram-positive and gram-negative bacteria via inhibiting protein synthesis. Chloramphenicols also inhibit protein synthesis but are rarely used due to toxicity risks like bone marrow suppression. Nitrofurantoin is primarily used for urinary tract infections as it is not absorbed systemically and concentrates in the urine.

1. Broad-spectrum antibiotics
&
Nitrofurantoin
Roll no. 136-150

2. • Gram Negative Organisms
●Cocci:--[Neisseria meningitidis]
[Neisseria Gonococci ]
●Bacilli:-- E.Coli
Salmonella
Shigella
Klebsiella

3. Broad-spectrum antibiotics

5. Tetracyclines
Pharmacokinetics
● Oral absorption: incomplete; avoid use with milk, iron preparation and anti-acid
drugs.
● Distribution: widely; easy to accumulate in bone and teeth.Excretion: mainly from
bile and urine; exists enterohepatic circulation.

6. Antimicrobial activity, mechanism, and spectrum
● Efficacy: quick bacteriostatic;
● Mechanism: inhibit bacterial protein synthesis by binding to the 308 subunit and
blocking tRNA binding to the A site.
● Spectrum: broad spectrum of activity
○ G+: <penicillin, cephalosporin
○ G-:<aminoglycosides
○ Others: chlamydia, mycoplasma, rickettsia, leptospira, amoeba.

7. Therapeutic uses
● Richettsiae infections: ship fever;
● Mycoplasmal pneumonia (first choice);
● Chlamydia infections: cervicitis, urethritis, trachoma.
● G+ and G infections (second line choice) 5. Penicillin-resistant
staphylococcus aureus.

8. Chloramphenicols
Pharmacokinetics
● Oral absorption: rapidly and completely absorbed;
● Distribution: all tissues and body fluids including CNS;
● Excretion: metabolized and then eliminated from kidney.

9. Antimicrobial activity, mechanism, and spectrum
● Efficacy: quick bacteriostatic;
● Mechanism: inhibit protein synthesis of bacteria
● Spectrum: aerobic and anaerobic gram-positive and gram negative organisms.
Chloramphenicol binds to the
305 mal want at the peptidyltransferases
and inhibits the transpeptidation reaction.

10. Clinical uses
● In general, it is rarely used due to toxicity.
○ Typhoid fever (first choice: third-generation cephalosporins and quinolones);
○ Bacterial meningitis (first choice: third-generation cephalosporins)
○ Anaerobic infections (alternative drugs);
○ Rickettsial diseases (first choice: tetracyclines)
○ Brucellosis (first choice: tetracyclines)

11. Adverse reaction
● Bone marrow suppression
○ (1) A dose-dependent, reversible depression of erythrocyte, platelet and leucocyte formation that
occurs early in treatment;
○ (2) An idiosyncratic, non-dose related and usually fatal aplastic anemia.
● Grey baby syndrome: circulatory collapse (neonates forbidden, daily
dosage<25mg/kg);
● Secondary infection;
● Hypersensitivity reactions.

12. Nitrofurantoin
Bacterial Spectrum:
● E. coli
● Some Gm+ cocci are susceptible.

13. Mechanism of action
Sensitive bacteria reduce the drug to an active agent that inhibits various enzymes →
damage bacterial DNA.
Antibacterial concentration is not attained in blood or tissues
Not to be used with Probenecid, azotemic patients: interferes with tubular secretion of
drug.

14. Pharmacokinetics
● Absorption is complete after oral use
● Metabolized & excreted rapidly that has no systemic antibacterial action
● Excreted in the urine
● It turns urine brown.
● Must be given with food or milk
● Keep urinary pH below 5.5 (acidic) to enhance drug activity

15. Therapeutic uses
● As urinary antiseptics (little or no systemic antibacterial effect)
○ Dose: 100 mg (orally four times daily)
○ Not associated with prostatitis
○ Supportive long term therapy
○ Long term porphylaxis
○ Following catheterization, instrumentation, in women with recurrent cystitis

16. Contraindications
● Patients with G 6P deficiency
● Neonates
● Pregnant women

17. Adverse effects of nitrofurantoin
● Gastrointestinal Intolerance: Nausea, epigastric pain,diarrhoea
● Hypersensitivity: fever,chills
● Peripheral neuritis and other neurological effects with long termuse
● Hematologic disorders: leukopenia, granulocytopenia, Hemolytic anemia in
G6PD deficientpatients
● Liver damage, pulmonary reaction with fibrosis on chronicuse

18. THANK YOU