Bacterial Diseases
Victor Politi,M.D., FACP, Medical Director,
SVCMC School of Allied Health Professions,
Physician Assistant Program
Introduction
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Bacteria consist of only a single cell
Bacteria fall into a category of life called
the Prokaryotes
There are thousands of species of
bacteria, but all of them are basically one
of three different shapes.
Classification of Bacteria
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Until recently classification has done on the basis
of such traits as:
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shape
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bacilli: rod-shaped
cocci: spherical
spirilla: curved walls
ability to form spores
method of energy production (glycolysis for anerobes,
cellular respiration for aerobes
nutritional requirements
reaction to the Gram stain.
Classification of Bacteria
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The Gram stain is named after the 19th
century Danish bacteriologist who developed it.
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The bacterial cells are first stained with a purple dye
called crystal violet.
Then the preparation is treated with alcohol or
acetone.
This washes the stain out of gram-negative cells.
To see them now requires the use of a counterstain of
a different color (e.g., the pink of safranin).
Bacteria that are not decolorized by the
alcohol/acetone wash are gram-positive
Gram Positive Bacteria
I-Gram Positive Cocci
A-Streptococcus (e.g. streptococcus Pneumoniae)
B-Staphylococcus (e.g. Staph. aureus)
C-Enterococcus (Previously Group D Strep.)
II-Gram Positive Rods
A-Corynebacteria: Corynebacterium diphtheria
B-Listeria monocytogenes
C-Bacillus anthracis (Anthrax)
D-Erysipelothrix rhusiopathiae
III-Gram Positive Branching Organisms
A-Actinomycetes
Gram Positive Cocci
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I-Beta-hemolytic Streptococcus (Lancefield Groups)
Group A Streptococcus (Streptococcus Pyogenes)
Group B Streptococcua (Streptococcus agalactiae)
Group C Streptococcus
Group G Streptococcus
II-Alpha-hemolytic Streptococcus
Streptococcus Pneumoniae (Pneumococcus)
- Viridans streptococcus (bacterial endocarditis)
III-Non-hemolytic Streptococcus
Streptococcus faecalis (Group D)
Certain members of Groups B, C, D, H, and O

Strep throat is caused by group A Streptococcus
bacteria. These bacteria are spread through
direct contact with mucus from the nose or
throat of persons who are infected, or through
contact with infected wounds or sores on the
skin
Group B Streptococcus
(Streptococcus agalactiae)
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Epidemiology
Most common US cause of neonatal sepsis
and meningitis
Incidence
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Overall: 2 to 4 per 1000 live births
Invasive: 1.8 per 1000 live births
Primarily occurs in newborns
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Very rare after 5 months of age
Group B Streptococcus
(Streptococcus agalactiae)
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Pathophysiology
Group B Beta-hemolytic streptococcus infection
Perinatal transmission
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Delivery via a birth canal colonized with GBS
Incidence of U.S. vaginal GBS colonization: 15-20%
Onset of infection (Mean onset 20 hours of life)
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Early onset neonatal disease (<6 days of life in 80%)
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Sepsis
Pneumonia
Late onset neonatal disease of sepsis or mengitis
Group B Streptococcus
(Streptococcus agalactiae)
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Labs: Maternal Screening
GBS Culture
Management
Sepsis (treat for 10-14 days)
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Meningitis (treat for 14-21 days)
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Pencillin G 200,000 units/kg/day divided q4-6 hours
Penicillin G 400,000 units/kg/day divided q2-4 hours
Prevention
Perinatal Group B Streptococcus Prophylaxis
Prognosis
Mortality 10-40%
Streptococcus Pneumoniae
(Pneumococcus)
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Epidemiology
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Most common cause of community acquired
pneumonia
Classic Symptoms
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Shaking rigors
Fever
Purulent sputum
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Rust colored
Pleuritic chest pain
Dyspnea
Chest splinting
Alpha-hemolytic Streptococcus
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Lab
CBC
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Gram stain
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Positive in only 33% of cases
Sputum culture
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Gram positive encapsulated organisms
Elongated lancet shaped diplococci
Blood Culture
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WBC elevated with left shift
Positive in only 40% of pneumococcal pneumonias
Radiology
Chest X-ray
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Lobar consolidation (often lower lobe)
patchy infiltrates
Management
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Increasing Pencillin Resistance
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Penicillin Sensitive
Ampicilin IV or Amoxicillin PO
Erythomycin
Azithromycin
Clarithromycin
Penicillin G IV
Doxycycline
Oral second generation cephalosporin
Parenteral third generation cephalosporin
Management
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High-Level Penicillin Resistance
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Broad spectrum Fluoroquinolone
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Levofloxacin
Gatifloxacin
Grepafloxacin
Moxifloxacin
Sparfloxacin
Parenteral third generation Cephalosporin
High dose Ampicillin
Vancomycin IV with or without Rifampin
Gram Positive Cocci
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Organisms
-Staphylococcus aureus
-Staphylococcus epidermidis
Pus smear (wound)
Staphylococcus aureus
Enterococcus
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I-Characteristics
Gram Positive Cocci
Previously defined as Group D Streptococcus
II-Organisms
Enterococcus faecalis
Enterococcus faecium
Gram Positive Rods
Corynebacterium
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Epidemiology
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Rare in United States due to Immunization
(DTP, DTaP)
However 20% of adults may be inadequate
immune status
 Ongoing epidemic in the former USSR
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Etiology
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Corynebacterium Diphtheriae
Corynebacterium
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Symptoms
sore throat
dysphagia
Weakness
Malaise
Corynebacterium
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Signs
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Toxic appearance
fever
Tachycardia (out of proportion to fever)
Pharyngeal erythema
Gray-white tenacious exudate or "membrane"
Occurs at tonsillar pillars and posterior pharynx
Leaves focal hemorrhagic raw surface when removed
Cervical lymphadenopathy
Differential Dx
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Vincent's Angina (trench mouth)
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Pharyngitis
Labs
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Also shows pseudomembrane formation
CBC
Leukocytosis
Throat culture (+ for corynebacterium org.)
Management
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Diphtheria antitoxin
Erythromycin
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20-25 mg/kg q12 hours IV for 7-14 days
Prevention
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DTP/DTaP vaccination
Listeria monocytogenes
Bacillus anthracis (Anthrax)
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Etiology
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Transmission
Contact with hides of infected animals
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Cattle
Sheep
Camels
Antelopes
Ingestion of contaminated meat
Inhalation of spores
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Bacillus anthracis
Infective aerosol dose: 8,000-50,000 spores
Spores may remain viable in soil for >40 years
No transmission person to person
Bacillus anthracis (Anthrax)
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Symptoms and Signs: Cutaneous
("Malignant Pustule")
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Inoculation at site of broken skin
Painless pruritic pustules develop at inoculation site
Begins as erythematous papule on exposed skin
Vesiculates and then ulcerates within 1-2 days
Surrounded by a ring of non-tender Brawny
edema
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Black eschar may form
Bacillus anthracis (Anthrax)
Bacillus anthracis (Anthrax)
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Symptoms and Signs: Inhalation Anthrax
Malaise
Regional lymphadenopathy
Two phases
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Initial Phase
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Viral upper respiratory symptoms
rhinorrhea
pharyngitis
Later Phase
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dyspnea and hemoptysis during dissemination
Symptoms and Signs:
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Acute GI type symptoms
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Hematemesis
Severe diarrhea
Differential Diagnosis
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Cutaneous Anthrax
Spider bite
Ecthyma gangrenosum
Ulceroglandular tularemia
Plague
Staph. Or strep. cellulitis
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Inhalational Anthrax
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Community acquired
pneumonia (late phase
anthrax)
Mycoplasma pneumonia
(early phase anthrax)
Influenza (early phase
anthrax)
Legionnaires' Disease
Psittacosis
tularemia
Q fever
Viral pneumonia
Histoplasmosis
Coccidiodomycosis
Bacillus anthracis (Anthrax)
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Labs
Rapid ELISA test now available
Cultures
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Gram stain - blood or vesicular fluid from lesion
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Gram positive bacilli
CBC
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Blood culture (high sensitivity)
Cultures of Vomitus or feces (Intestinal Anthrax)
CSF culture (Inhalational Anthrax)
Nasal Swab (Epidemiologic tool to identify outbreak)
Sputum culture (Inhalational Anthrax)
Vesicular fluid (Cutaneous Anthrax)
Neutrophilic leukocytosis in severe cases
Radiology:
Chest x-ray - Widened Mediastinum (hemorrhagic mediastinitis
Management: Antibiotics
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Antibiotic course: 60
days
Empiric Treatment
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Cipro
 Adults: 400 mg IV q12
hours
 Children: 20-30
mg/kg/day IV divided
q12 hours
Levofloxacin
 Adults: 500 mg IV q24
hours
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Specific Treatment for
confirmed anthrax
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Adults
Pencillin G 4 MU IV q4
hours or
 Doxycycline 200 mg IV,
then 100 mg IV q12
hours
Children > age 12 same as
adults
Children < age 12
 Penicillin G 50,000 U/kg
IV q6 hours
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Postexposure prophylaxis
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Concurrently begin vaccination
Continue antibiotics for 60 days
Ciprofloxacin
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Amoxicillin
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Adults: 500 mg PO bid
Children: 20-30 mg/kg/day divided bid up to 1g/day
Adults: 500 mg PO tid
Children: 40 mg/kg up to 500 mg PO tid
Doxycycline
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Adults: 100 mg PO bid
Children over age 8: 5 mg/kg/day divided q12 hours
Anthrax
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Course
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Incubation: 4-6 days
Duration of illness: 3-5 days
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Prognosis
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Inhalation Anthrax (inhaled spores)
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Cutaneous Anthrax (skin contact)
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Untreated: 95% mortality
Treated: 80% mortality
Untreated: 20% mortality
Treated: Rare mortality
Intestinal Anthrax (ingested contaminated meat)
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Prevention
Anthrax Vaccine 93% effective
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Initial: 0, 2, and 4 weeks
Next: 6, 12, 18 months and then annually
Postexposure Prophylaxis as above
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Empiric prophylaxis for any suspected
exposure
Best prognosis with antibiotics prior to
symptoms
Gram Negative
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Gram Negative Rods
Anaerobes
 Bacteroidaceae (e.g. Bacteroides fragilis)
Facultative Anaerobes (enteric/nonenteric)
 Enterobacteriaceae (e.g. Escherichia coli)
 Vibrionaceae (e.g. Vibrio Cholerae)
 Pasturella,Brucella,Yersinia
Aerobes
 Pseudomonadaceae (e.g. Pseudomonas aeruginosa)
Facultative Anaerobes
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Enterobacteriaceae (e.g. E. coli)
Vibrionaceae (e.g. Vibrio Cholerae)
Salmonella,Shigella,Klebsiella,Proteus
GI pathogens !!!!!
non-enteric Pasturella,Brucella,Yersinia
Francisella,Hemophilus,Bordetella
Enterobacteriaceae
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Characteristics
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Facultative Anaerobic Gram negative rods
EKP Gram negative bacteria
Escherichia coli
Klebsiella
Proteus
Vibrionaceae
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Characteristics
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Facultative Anaerobic gram negative rods
Vibrio Cholerae
Vibrio parahaemolyticus
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Genus: Aeromonas (motile with single
polar flagellum)
Vibrionaceae
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Genus: Campylobacter (motile with
single polar flagellum)
Campylobacter jejuni
Genus: Helicobacter (motile with
multiple flagella)
Helicobacter Pylori
Pasteurellaceae
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Characteristics
Facultative Anaerobic gram negative rods
Genus: Pasteurella
Pasteurella multocida
Pasteurellaceae
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Genus: Haemophilus (coccobacilli)
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Haemophilus Influenzae
Haemophilus aegyptius
Haemophilus ducrei
Gram Negative Rod
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Aerobes
Pseudomonadaceae (e.g. Pseudomonas
aeruginosa)
Brucella
Legionellaceae
Pseudomonadaceae
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Characteristics
Aerobic Gram Negative Rod
Family: Pseudomonadaceae
Pseudomonas aeruginosa
Pseudomonas mallei (Glanders)
Gram Negative Rod Aerobic
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Family: Legionellaceae
Legionella pneumophila
Legionellaceae
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Pathophysiology
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Aerobic, intracellular, Gram
negative rod
 Virulent organism
 More severe disease than
other atypical pneumonia
Transmission
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Waterborne
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Transmission
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Optimal conditions for growth
 Temperature: 89 to 113 F
water
 Stagnant water
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Freshwater or moist soil
near ponds
Air conditioning
Condensers
Cooling towers
Respiratory therapy
equipment
Showers or water faucets
Whirlpools
Incubation
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Two to ten days
Legionellaceae
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Symptoms
Prodrome for 12-48 hours
 Malaise
 Myalgia
 HA
Symptoms for 2-3 days
 Fever to 40.5 C
persists for 8-10 days
 GI symptoms- 20-40%
of cases
 Nausea/vomiting
 Diarrhea
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Later Symptoms: Cough
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Minimal to no sputum
production
Slightly blood tinged
sputum
Signs
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Severe respiratory distress
Confusion
Disorientation
Legionella pneumophila
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Complications
Respiratory failure (20-40% of cases)
Extrapulmonary complications
 Myocarditis/pericarditis
 Prosthetic valve endocarditis
 Glmoerulonephritis
 Pancreatitis
 Peritonitis
Legionella pneumophila
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Radiology: chest x-ray
Small pleural effusions
Unilateral parenchymal infiltrates
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Round, fluffy opacities
Spread contiguously to other lobes
Progresses to dense consolidation
Progresses to bilateral infiltrates
Legionella pneumophila
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Labs
CBC
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Erythrocyte Sedimentation Rate
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leukocytosis
leukopenia
Elevated markedly
LFTs increased
Sputum Exam
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Fluorescent antibody studies of sputum
Legionella can not be seen on gram stain
Legionella pneumophila
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Diagnosis
Legionella urine antigen testing
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High sensitivity/ serogroup 1
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Sputum Culture - to ID other serogroups
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Serogroup 1 (LP1) causes most U.S. cases
Urine antigen and sputum culture all cases
Legionella Serologies
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Legionella fourfold titer rise to >= 1:128 or
Legionella titer >= 1:256
Legionella pneumophila
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Management (Antibiotic course for 21
days)
Azithromycin IV
Levofloxacin IV
Trovafloxacin IV
Erythromycin IV
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Add Rifampin in immunocompromised or severe
disease
Course
Response to antibiotics may not be seen for 4-5
days
Up to 15% mortality in some studies
Brucellosis
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Epidemiology
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US Incidence
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<100 cases per year (0.34/100,000)
Etiology
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Brucella abortus
Brucella suis
Brucella melitensis
Brucellosis
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Pathophysiology
Facultative intracellular parasite
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Releases endotoxin when dies
Infective dose: 10-100 organisms
Incubation: 5-60 days
Brucellosis
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Transmission
Infected animal products
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Tissue from Sheep in U.S.
Unpasteurized milk
Vaccine exposure
No transmission person to person
Enters via mucus membranes, broken
skin, or inhalation
Brucellosis
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Risk Factors
Veterinarians
Farm workers
Meat processing plants
Travel or residence in endemic region
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Mediterranean
India
North Africa, East Africa
Central Asia, South Asia
Brucellosis
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Symptoms
Intermittent fevers
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Undulating fever
Temperature peaks in evening to 101-104
Arthralgia (90%)
Weakness
Lassitude
Weight loss
Headache
Sweating
Chills
Brucellosis
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Course
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Weeks to months
Prognosis
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Case Fatality
<5% treated
Gram Negative Cocci
Aerobes
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Moraxella(Branhamella catarrhalis)
Acinetobacter
Neisseria
Neisseriaceae
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Neisseria meningitidis
Neisseria gonorroeae
Neisseria gonorrhoeae
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Epidemiology
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Incidence: 500-700,000 cases per year
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Much less common than chlamydia
Decreasing except in inner city, drug abuse (crack)
Highly contagious: 50% transmission
Chlamydia coexists in 45-50% of patients with
gonorrhea
Pathophysiology
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Incubation: 2-7 days
Neisseria gonorrhoeae
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Symptoms and Signs: General
Urinary Symptoms
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Copious urethral discharge
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Urinary frequency
Urinary urgency
Dysuria
Green, yellow, or sanguinous discharge
Meatus and anterior urethra inflammation
Neisseria gonorrhoeae
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Conjunctivitis
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Direct inoculation
Copious exudate
Beefy Conjunctiva
Serious complications
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Pharyngitis
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Corneal ulceration or opacification
Visual loss
Globe perforation
Rarely the only site of infection
Usually asymptomatic
Acute Diarrhea
Neisseria gonorrhoeae
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Symptoms and Signs: Women
Mucopurulent Cervicitis
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Often asymptomatic
Vaginal d/c or spotting
Bartholin’s Gland inflammation
Skene's gland inflammation
Neisseria gonorrhoeae
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Symptoms and Signs: Men (often
asymptomatic)
Epidiymitis under age 35 years
Proctitis
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Receptive anal intercourse or vaginal
secretions
Mild anal irritation or itching
Neisseria gonorrhoeae
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Symptoms and Signs: Disseminated
Infection
More common in pregnancy
Dermatitis
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Rash over trunk, extremities, palms and soles
Necrotic pustule on red base over distal extremity
May become hemorrhagic
Usually less than 20 total lesions
Tenosynovitis
Gonococcal arthritis
Endocarditis risk
Neisseria gonorrhoeae
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Complications
PID
Systemic Gonorrhea
Chronic Arthritis
Neonatal Gonorrhea
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Gonorrheal conjunctivitis
Preterm labor
Neisseria gonorrhoeae
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Labs
Gram stain: Urethral /cervical smear
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Numerous WBCs
Gram negative biscuit-shaped diplococci
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Gonorrhea culture and Sensitivity
Antigen Testing (e.g. Gonozyme)
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False positive Gram stain (saprophytic Neisseria)
Indicated in symptomatic men
Inaccurate in other populations
DNA probe testing
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Rapid: 30 minutes
Sensitivity: 85-100%
Specificity: 99-100%
Neisseria gonorrhoeae
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Management: Drug Resistance
Tetracycline resistance: 17-23%
Penicillin resistance 15-19%
Emerging Fluroquinolone resistance
No resistance to 3rd generation cephalosporins
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Ceftriaxone (Rocephin)
Cefixime (Suprax)
Azithromycin requiring higher dosages for some
GC
References
Moraxella catarrhalis
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Diagnosis
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Represents less than 5% of all pneumonias
More common in COPD
Lobar consolidation is rare
Moraxella catarrhalis
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Labs
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Gram stain
Kidney bean shaped gram negative diplococci
Radiology
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Chest xray
patchy bronchopulmonary
infiltrate
Moraxella catarrhalis
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Management: Antibiotic
Amoxicillin-clavulanate (Augmentin)
Second generation Cephalosporin (e.g. Cefuroxime)
3rd generation Cephalosporin (e.g. Cefotaxime)
Erythromycin
Azithromycin (Zithromax)
Clarithromycin (Biaxin)
Trimethoprim Sulfamethoxazole (Bactrim or Septra)
Doxycycline
Gram Negative Obligate
Intracellular Parasites
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Rickettsia
Ehrlichia
Coxiella
Rochalimaea (not obligate intracellular)
Rickettsia
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Genus: Rickettsia
Typhus Group
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Spotted Fever Group
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Rickettsia prowazekii (epidemic typhus,louse)
Rickettsia mooseri
Rickettsia rickettsii (rmsf,tick)
Scrub Typhus Group
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Rickettsia tsutsugamushi (scrub typhus,)
Rickettsia rickettsii
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Pathophysiology
Transmission: Tick bite
Infects blood vessel walls
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Endothelial cells
Smooth muscle cells
Rickettsia rickettsii is causative organism
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Small pleomorphic organism
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Obligate intracellular parasite
Rocky Mountain Spotted Fever
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Epidemiology
Bimodal age distribution
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Ages 5 to 9 years old
Age over 60 years old
Endemic area
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North America
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Atlantic coast states
Midwest
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Central America
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South America
Rocky Mountain Spotted Fever
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Symptoms (follows seven day
incubation)
Fever
HA
Myalgias
Malaise
vomiting
Rocky Mountain Spotted Fever
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Signs: Rash (occurs in 90% of patients)
Onset in first week of illness
Characteristics
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Distribution
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Initial: Blanching Macules 1 to 4 mm in diameter
Later: Macules transition to Petechiae
Onset: Wrists and Ankles
Later: Trunk, Palms and Soles
Labs
Rocky Mountain Spotted Fever
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Labs
CBC
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Liver transaminases increased
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AST /ALT
Serum sodium -Hyponatremia
Cerebrospinal Fluid
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WBC normal or slightly decreased
Thrombocytopenia
CSF pleocytosis w/monocytic predominance
Rickettsia Serology
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Positive 7 to 10 days after symptom onset
Used for confirmation, not for diagnosis
Rocky Mountain Spotted Fever
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Management
Antibiotic Course
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Minimum course: 5 to 7 days
Continue antibiotics until afebrile for 2 days
Antibiotics
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Doxycycline or Tetracycline or
Chloramphenicol
Rocky Mountain Spotted Fever
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Complications
Encephalitis
Noncardiac pulmonary edema
ARDS
Cardiac arrhythmia
Coagulopathy
GI bleeding
Skin Necrosis
Rocky Mountain Spotted Fever
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Prognosis
Untreated:
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25% Mortality within 8 to 15 days
Treated:
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5% Mortality
Ehrlichia
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Ehrlichia sennetsu
Ehrlichia canis
Coxiella
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Coxiella burnetii – Q fever, no arthropod
vector cattle,sheep, goats, inhallation of
dust with dried feces urine or milk
Rochalimaea (not obligate
intracellular)
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Rochalimaea quintana (trench fever seen
in military settings)
Chlamydia
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Eye Diseases
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Trachoma
Inclusion conjunctivitis
Genitourinary Disease
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Lymphogranulmoa
venereum
Urethritis
cervicitis
Salpingitis
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Respiratory
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Other
Chlamydia psittaci
(Human psittacosis)
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Chlamydia pneumonia in
newborns
Bird borne zoonosis
Respiratory illness or
typhoidal illness
Chlamydia pneumoniae
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pneumonia
Chlamydia trachomatis
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Epidemiology: Very Prevalent
Asymptomatic teenage female test
positive: 5-10%
Sexually active persons: 10%
Chlamydia 6 to 10 times more common
than Gonorrhea
Incidence: 3-5 million cases/year
Chlamydia Trachomatis (obligate
intracellular organism)
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Cause
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Complications
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Chlamydia Trachomatis (obligate intracellular
organism)
PID
Infertility
Preterm labor
Perinatal transmission to newborn
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Chlamydia conjunctivitis
Neonatal pneumonia
Chlamydia Trachomatis (obligate
intracellular organism)
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Symptoms: Women
Vaginal d/c
dysuria
Pelvic pain
Untreated infections may persist for months
Usually asymptomatic
Urethritis
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Dysuria-Sterile pyuria Syndrome
Persistent dysuria and pyuria
Negative urine culture
Chlamydia Trachomatis (obligate
intracellular organism)
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Symptoms: Men
Urethritis
Often symptomatic
Associated Conditions: Reiter’s
Syndrome in Men
Arthritis
Conjunctivitis
Urethritis
Chlamydia Trachomatis (obligate
intracellular organism)
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Management
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First Choice
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Refer all sexual contacts for treatment
Azithromycin 1 gram PO for 1 dose
Doxycycline 100 mg PO bid for 7 days
Alternatives
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Ofloxacin 300 mg PO bid for 7 days
Erythromycin 500 mg PO qid for 7 days
Erythromycin Ethylsuccinate (EES)
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Dose: 800 mg PO qid for 7 days
Amoxicillin 500 mg PO tid for 7 days
Clindamycin 450 mg PO qid for 14 days
Chlamydia Trachomatis (obligate
intracellular organism)
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Pregnancy
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Azithromycin 1 gram PO as single dose
Erythromycin OR EES as above for 7 days
Amoxicillin 500 PO tid x7 days (Only 50%
effective)
Neonates (conjunctivitis or pneumonia)
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Erythromycin for 14 days
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Questions ??????