Microbiology, Infections, and Antibiotic Therapy

Microbiology, Infections, and Antibiotic Therapy
Presentation by: Elizabeth J. Rosen, MD
Francis B. Quinn, MD


Basic Bacteriology
Shape
Arrangement
Gram Staining
Cell Wall Characteristics

* Gram Positive
* Gram Negative

Bacterial Growth

* Binary Fission = Exponential Growth
* Four Phases of Growth

Normal Bacterial Flora
Host Defense Mechanisms

* Nonspecific Immunity
o barriers
o inflammatory response
* Specific Immunity
o Passive
o Active
+ humoral
+ cell-mediated

Clinical Microbiology

* Gram Positive Cocci
* Gram Positive Bacilli
* Gram Negative Cocci
* Gram Negative Bacilli
* Anaerobes
* Spirochetes
* Mycobacteria

Gram Positive Cocci

* Staphylococcus
* Streptococcus

Staphylococcus

* S. aureus, S. epidermidis, S. saprophyticus
* S. aureus

Streptococcus

* S. viridans
o oral flora
o infective endocarditis
S. pyogenes

* Group A, beta hemolytic strep
* pharyngitis, cellulitis
* rheumatic fever
+ fever
+ migrating polyarthritis
+ carditis
+ immunologic cross reactivity
* acute glomerulonephritis
+ edema, hypertension, hematuria
+ antigen-antibody complex deposition
S. pneumoniae

Gram Negative Cocci

* Neisseria
o meningitidis
o gonorrhea
* Moraxella catarrhalis

Gram Positive Bacilli

* Clostridium
* Bacillus
* Corynebacterium
* Listeria
* Actinomyces
* Nocardia

C. tetani
C. botulinum

* Descending weakness-->paralysis
* diplopia, dysphagia-->respiratory failure

C. perfringens
C. diphtheriae

* Fever, pharyngitis, cervical LAD
* thick, gray, adherent membrane
* sequelae-->airway obstruction, myocarditis
* colony morphology
L. monocytogenes
Actinomyces

* Part of normal oral cavity flora
* 50% of infections occur in face & neck
* forms abscesses with sulfur granules
* draining sinus tracts

Nocardia
Gram Negative Bacilli

* Facultative Anaerobes
o Respiratory
# Haemophilus
# Bordetella
# Legionella
o Zoonotic
# Yersinia
# Francisella
# Pastuerella
o Enteric
# Klebsiella
# Serratia
# Proteus
# Enterobacter

* Strict Aerobes
o Pseudomonas
* Anaerobes
o Bacteroides

Enterobacteriaceae
K. rhinoscleromatis
* Catarrhal
o purulent rhinorrhea
* Granulomatous
o mucosal nodules
* Cicatricial
o fibrosis
o stenosis

H. influenzae
Legionella

* Community and Nosocomial pneumonia
* contaminated water sources
B. pertussis
Zoonotic Gram Negative Rods

* Yersinia
o plague
* Franciscella
o tularemia
* Pasturella
o dog/cat bites

Pseudomonas
Anaerobic Bacteria

* Bacteroides
* Fusobacterium
* Peptostreptococcus
* Actinomyces
* Prevotella

Spirochetes

* Treponema
* Borrelia

Manifestations of Syphilis
Lyme Disease

* Cutaneous lesions
o erythema chronicum migrans
* Nonspecific symptoms
o malaise, fatigue, headache, fevers, chills, myalgias, arthralgias, lymphadenopathy
* Late manifestations
o neurologic
o cardiac

M. tuberculosis

* Pulmonary disease (82%)
* Extrapulmonary disease (18%)

ENT Manifestations of TB

* Scrofula
o matted lymphadenopathy: posterior triangle
* Laryngeal TB
o edema, ulcers, polypoid changes: arytenoids
* Oral TB
o painless ulcers: tongue
* Aural TB
o thickened TM-->hyperemia-->multiple perfs
o thin, watery otorrhea-->thick, cheesy d/c
M. leprae

Antibiotic Therapy

* Identify infecting organism
* Evaluate drug sensitivity
* Target site of infection
* Drug safety/side effect profile
* Patient factors
* Cost

Classification of Antibiotics

* Bacteriostatic
* Bactericidal
* Chemical Structure
* Spectrum of Activity
* Mechanism of Action

Mechanism of Action
Inhibitors of Cell Wall Synthesis
Beta Lactam Antibiotics

* Penicillins
* Cephalosporins
* Carbapenems
* Monobactams
Penicllins

* Derived from the fungus Penicillium
* Therapeutic concentration in most tissues
* Poor CSF penetration
* Renal excretion
* Side effects: hypersensitivity, nephritis, neruotoxicity, platelet dysfunction

Natural Penicillins

* Penicillin G, Penicillin V

Antistaphylococcal Penicillins
Aminopenicillins
Antipseudomonal Penicillins
Cephalosporins
Generations of Cephalosporins
Monobactams
Carbapenems
Vancomycin
Protein Synthesis Inhibitors
Tetracyclines
Aminoglycosides
Macrolides
Erythromycin
Alternate Macrolides
Chloramphenicol
Clindamycin
Inhibitors of Metabolism
Sulfonamides
Trimethoprim
Co-Trimoxazole (TMP/SMX)
Inhibitors of Nucleic Acid Function/Synthesis
Fluoroquinolones
Antimycobacterial Therapy
First-Line Agents
Antimycobacterials for Leprosy
Antibiotic Prophylaxis
Classification of Wounds
Classification of Wounds
Prophylactic Antibiotics
Effective Prophylactic Regimens
Topical Antibiotic Prophylaxis
Indications for Antibiotic Prophylaxis in ENT Surgery

Microbiology, Infections, and Antibiotic Therapy.ppt