GENERAL BACTERIOLOGY

• Morphology

  • Spherical (coccus)
  • Rod (bacillus)
  • Comma (vibrio)
  • Corkskrew (spirochete)
  • Spiral (spirila)
• Spectrum of Activity - arsenal/list of microbes that can be targeted by medicines
• Sites of Action

  • Cell wall (cidal)
  • Cell membrane (cidal)
  • Nucleic acid: DNA & RNA (cidal); Folate precrusor (static)
  • Ribosomes (static)
• Source of Antibiotics

  • Cell membrane inhibitors

  1. Daptomycin (Streptomyces roseosporus)
  2. Bacitracin (Bacillus subtilis)

  • Antitubercular agents

  1. Rifampicin (Streptomyces mediterranei)
  2. Cycloserine (Streptomyces orchidaceous)
• Bactericidal Agents

  • DNA synthesis inhibitor: Fluoroquinolones (FLOXACIN)
  • RNA synthesis
• Beta-Lactam Antibiotics

  • Ineffective

  1. Cell wall-less microbes
  2. Acid fast bacteria
  3. Intracellular parasites
  4. Resistant microorganisms

  • Adverse reactions

  1. Allergy/anaphylactic (DOC: Erythromycin)
• Natural Penicillins

  • Penicillin G/Benzylpenicillin

  1. Intramuscular -> acid-labile
  2. DOC for leptospirosis, meningococcus, & syphilis
• Beta-Lactamase Inhibitors

  • Class I (beta-lactamase only)

  1. Clavam (Clavulanic acid)
  2. Penam (Sulbactam + Tazobactam)

  • Ampicillin + Sulbactam = UNASYN
  • Piperacillin + Tazobactam = PIPTAZ / TAZOCIN
• Cephalosporins

  • 1st Gen (ceph- & cefa-) [except cefamandole & cefaclor]
  • 2nd Gen (cef- & -lor-)
  • 3rd Gen (cef- + -em/-ine /-one) [except cefapime & cefuroxime]
  • 4th Gen (cef- + -pi- + -me)
  • 5th Gen (-rol-)
• Carbapenems - wildest spectrum among the beta-lactams

  • Doripenem - wildest spectrum carbapenem
• Vancomycin

  • MOA: binds to D-alanyl-D-alanine portion → blockade of transpeptidation
  • USES: DOC (drug of choice) for MRSA (methicillin-resistant Staphylococcus aureus) & MRSE (Methicillin-resistant Staphylococcus epidermidis) 2nd line treatment for pseudomembranous colitis
  • A/E: red man syndrome - Tx: Diphenhydramine + Discontinue (temporarily)
• Tetracyclines (Broadest-Spectrum antibiotic)

  • USES: DOC for relapsing fever, lymphogranuloma venereum, psittacosis, rickettsia infection
  • DOXYCYCLINE; prophylaxis of leptospirosis; DOC for Lyme disease
  • MINOCYCLINE; most potent
• Aminoglycosides

  • STREPTOMYCIN = DOC for zoonotic infections
  • Brucellosis / undulant fever
  • Bubonic plague
  • Tularemia / rabbit fever
• Aminoglycosides (A/E)

  • VESTIBULOTOXICITY
  • Streptomycin & Gentamicin
  • OTOTOXICITY
  • Neomycin, Amikacin, & Kanamycin
  • NEPHROTOXICITY
  • Neomycin, Tobramycin, & Gentamicin
• CHLORAMPHENICOL

  • USES: former DOC for typhoid fever (current DOC: ceftriaxone)
• LINCOSAMIDES

  • MOA: resemble macrolides in receptor site, mode of action, and spectrum of activity
  • A/E: overuse of clindamycin → overgrowth of clostridium difficile bacteria → pseudomembranous colitis
• OXAZOLIDINONES

  • A/E: reversible thrombocytopenia
• MACROLIDES

  • ERYTHROMYCIN: DOC for diphtheria & pertussis
  • A/E: AZITHROMYCIN – ARRHYTHMIAS
• FLUOROQUINOLONES

  • CIPROFLOXACIN: 1st line agent for anthrax
  • CIPROFLOXACIN & LEVOFLOXACIN: UTI
• ANTIMETABOLITE COMBINATIONS

  • SULFAMETHOXAZOLE + TRIMETHOPRIM (COTRIMOXAZOLE) DOC for Pneumocystis carinii pneumonia in AIDS patients
• RIFAMPICIN

  • MOA: inhibits RNA polymerase → inhibits RNA synthesis
• DAPSONE

  • USE: TX of leprosy (with rifampicin)
• NITROIMIDAZOLE (METRONIDAZOLE, TINIDAZOLE)

  • MOA: inhibits protein synthesis, and causes DNA strand breakage
• METRONIDAZOLE

  • TRICHOMONAS VAGINALIS (TRICHOMONIASIS)
  • ANAEROBES: BACTEROIDES FRAGILIS (intestinal abscess) & CLOSTRIDIUM DIFFICILE (pseudomembranous colitis)
• URINARY ANTISEPTICS

  • FOSFOMYCIN
  • METHENAMINE: acidify the urine and liberate formaldehyde
  • NALIDIXIC ACID
  • NITROFURANTOIN