Miscellaneous Antibiotics Polymyxins Active against gram-negative including pseudomonas. Polymyxin B is only available. Bactericidal inhibits cell wall synthesis. Used only topically . Highly nephrotoxic.

Spectinomycin Bactericidal ,inhibits protein synthesis by binding to 30S ribosomal subunits. Active against gram positive & gram negative organisms. Rapidly absorbed after intramuscular injection. Excreted through kidney .

Clinical uses As an alternative treatment for drug- resistant gonorrhea or gonorrhea in penicillin –allergic patients. No cross-resistance with other drugs used in gonorrhea. A single intramuscular dose is given

Adverse effects Pain at the site of injection Fever And nausea Nephrotoxicity ( rare )

Clindamycin Active against gram-positive cocci Gram negative anaerobic organisms Inhibits protein synthesis by binding to 50S ribosomal subunits.

Pharmacokinetics Given orally or intravenously Highly bound to plasma proteins Distributes well into all body fluids & tissues except brain &CSF. Penetrates well into abscess & is taken up by phagocytic cells.

Metabolized by the liver. Both active drug & active metabolites are excreted in bile & urine No dosage adjustment is needed for renal failure.

Clinical uses Severe anaerobic infections ( bones and joints) . Conjunctivitis. In combination with aminoglycoside or cephalosporin to treat penetrating wounds of the abdomen & the gut. Infections in female genital tract ( septic abortion ,pelvis abscess ).

For prophylaxis of endocarditis in patients with valvular heart disease Plus primaquine is an effective alternative to co-trimoxazole for moderate or severe pneumocystis jiroveci pneumonia in AIDS patients

Adverse Effects Diarrhea , nausea, Skin rash Antibiotic-associated colitis Impaired liver function Neutropenia ( not common )

Vancomycin Bactericidal Inhibits bacterial cell wall synthesis Active on gram-positive bacteria including β-lactamase producer & those resistant to methicillin.

Pharmacokinetics Poorly absorbed from GIT Slow IVI is used for treatment of systemic infections. Widely distributed Cerebrospinal fluid levels are achieved in meningeal inflammation Excreted mainly through renal route

Clinical uses Endocarditis or sepsis mainly caused by methicillin –resistant staphylococci. Alternative to penicillin in enterococcal endocarditis( in combination with gentamicin). Meningitis( in combination with cephalosporin) Orally only for the treatment of antibiotic -associated enterocolitis

Adverse effects Phlebitis at the site of infusion Fever Ototoxicity & nephrotoxicity ( not common). Red man or red neck syndrome. Hypotension

Bacitracin Bactericidal Inhibits cell wall synthesis Active against gram +ve organisms Used only topically in skin ,eye ,nose infections . As ointment in combination with polymyxin or neomycin for mixed bacterial infections. As solution in saline for irrigation of joints, wounds or pleural cavity.

Adverse Effects Highly nephrotoxic producing proteinuria, hematuria Hypersensitivity reactions

Teicoplanin Similar to vancomycin in : Mechanism of action Antibacterial activity Given I.M. or I.V. long half-life(45-70 h). once daily.

Cycloserine Bactericidal Inhibits bacterial cell wall Effective on gram- positive & gram- negative organisms as well as M.tuberculosis. Rapidly absorbed orally Widely distributed in body tissues & fluids. Excreted as active form in urine Used in treatment of pulmonary & extrapulmonary tuberculosis C.N.S. toxicity ( headaches, tremors, acute psychosis, convulsions) Contraindicated in epileptic & psychotic patients