Gram Positive Bacteria
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Transcript Gram Positive Bacteria
Bacterial Diseases
Victor Politi,M.D., FACP, Medical Director,
SVCMC School of Allied Health Professions,
Physician Assistant Program
Introduction
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
Until recently classification has done on the basis
of such traits as:
shape
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
The Gram stain is named after the 19th
century Danish bacteriologist who developed it.
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
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)
Epidemiology
Most common US cause of neonatal sepsis
and meningitis
Incidence
Overall: 2 to 4 per 1000 live births
Invasive: 1.8 per 1000 live births
Primarily occurs in newborns
Very rare after 5 months of age
Group B Streptococcus
(Streptococcus agalactiae)
Pathophysiology
Group B Beta-hemolytic streptococcus infection
Perinatal transmission
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)
Early onset neonatal disease (<6 days of life in 80%)
Sepsis
Pneumonia
Late onset neonatal disease of sepsis or mengitis
Group B Streptococcus
(Streptococcus agalactiae)
Labs: Maternal Screening
GBS Culture
Management
Sepsis (treat for 10-14 days)
Meningitis (treat for 14-21 days)
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)
Epidemiology
Most common cause of community acquired
pneumonia
Classic Symptoms
Shaking rigors
Fever
Purulent sputum
Rust colored
Pleuritic chest pain
Dyspnea
Chest splinting
Alpha-hemolytic Streptococcus
Lab
CBC
Gram stain
Positive in only 33% of cases
Sputum culture
Gram positive encapsulated organisms
Elongated lancet shaped diplococci
Blood Culture
WBC elevated with left shift
Positive in only 40% of pneumococcal pneumonias
Radiology
Chest X-ray
Lobar consolidation (often lower lobe)
patchy infiltrates
Management
Increasing Pencillin Resistance
Penicillin Sensitive
Ampicilin IV or Amoxicillin PO
Erythomycin
Azithromycin
Clarithromycin
Penicillin G IV
Doxycycline
Oral second generation cephalosporin
Parenteral third generation cephalosporin
Management
High-Level Penicillin Resistance
Broad spectrum Fluoroquinolone
Levofloxacin
Gatifloxacin
Grepafloxacin
Moxifloxacin
Sparfloxacin
Parenteral third generation Cephalosporin
High dose Ampicillin
Vancomycin IV with or without Rifampin
Gram Positive Cocci
Organisms
-Staphylococcus aureus
-Staphylococcus epidermidis
Pus smear (wound)
Staphylococcus aureus
Enterococcus
I-Characteristics
Gram Positive Cocci
Previously defined as Group D Streptococcus
II-Organisms
Enterococcus faecalis
Enterococcus faecium
Gram Positive Rods
Corynebacterium
Epidemiology
Rare in United States due to Immunization
(DTP, DTaP)
However 20% of adults may be inadequate
immune status
Ongoing epidemic in the former USSR
Etiology
Corynebacterium Diphtheriae
Corynebacterium
Symptoms
sore throat
dysphagia
Weakness
Malaise
Corynebacterium
Signs
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
Vincent's Angina (trench mouth)
Pharyngitis
Labs
Also shows pseudomembrane formation
CBC
Leukocytosis
Throat culture (+ for corynebacterium org.)
Management
Diphtheria antitoxin
Erythromycin
20-25 mg/kg q12 hours IV for 7-14 days
Prevention
DTP/DTaP vaccination
Listeria monocytogenes
Bacillus anthracis (Anthrax)
Etiology
Transmission
Contact with hides of infected animals
Cattle
Sheep
Camels
Antelopes
Ingestion of contaminated meat
Inhalation of spores
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)
Symptoms and Signs: Cutaneous
("Malignant Pustule")
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
Black eschar may form
Bacillus anthracis (Anthrax)
Bacillus anthracis (Anthrax)
Symptoms and Signs: Inhalation Anthrax
Malaise
Regional lymphadenopathy
Two phases
Initial Phase
Viral upper respiratory symptoms
rhinorrhea
pharyngitis
Later Phase
dyspnea and hemoptysis during dissemination
Symptoms and Signs:
Acute GI type symptoms
Hematemesis
Severe diarrhea
Differential Diagnosis
Cutaneous Anthrax
Spider bite
Ecthyma gangrenosum
Ulceroglandular tularemia
Plague
Staph. Or strep. cellulitis
Inhalational Anthrax
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)
Labs
Rapid ELISA test now available
Cultures
Gram stain - blood or vesicular fluid from lesion
Gram positive bacilli
CBC
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
Antibiotic course: 60
days
Empiric Treatment
Cipro
Adults: 400 mg IV q12
hours
Children: 20-30
mg/kg/day IV divided
q12 hours
Levofloxacin
Adults: 500 mg IV q24
hours
Specific Treatment for
confirmed anthrax
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
Postexposure prophylaxis
Concurrently begin vaccination
Continue antibiotics for 60 days
Ciprofloxacin
Amoxicillin
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
Adults: 100 mg PO bid
Children over age 8: 5 mg/kg/day divided q12 hours
Anthrax
Course
Incubation: 4-6 days
Duration of illness: 3-5 days
Prognosis
Inhalation Anthrax (inhaled spores)
Cutaneous Anthrax (skin contact)
Untreated: 95% mortality
Treated: 80% mortality
Untreated: 20% mortality
Treated: Rare mortality
Intestinal Anthrax (ingested contaminated meat)
Prevention
Anthrax Vaccine 93% effective
Initial: 0, 2, and 4 weeks
Next: 6, 12, 18 months and then annually
Postexposure Prophylaxis as above
Empiric prophylaxis for any suspected
exposure
Best prognosis with antibiotics prior to
symptoms
Gram Negative
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
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
Characteristics
Facultative Anaerobic Gram negative rods
EKP Gram negative bacteria
Escherichia coli
Klebsiella
Proteus
Vibrionaceae
Characteristics
Facultative Anaerobic gram negative rods
Vibrio Cholerae
Vibrio parahaemolyticus
Genus: Aeromonas (motile with single
polar flagellum)
Vibrionaceae
Genus: Campylobacter (motile with
single polar flagellum)
Campylobacter jejuni
Genus: Helicobacter (motile with
multiple flagella)
Helicobacter Pylori
Pasteurellaceae
Characteristics
Facultative Anaerobic gram negative rods
Genus: Pasteurella
Pasteurella multocida
Pasteurellaceae
Genus: Haemophilus (coccobacilli)
Haemophilus Influenzae
Haemophilus aegyptius
Haemophilus ducrei
Gram Negative Rod
Aerobes
Pseudomonadaceae (e.g. Pseudomonas
aeruginosa)
Brucella
Legionellaceae
Pseudomonadaceae
Characteristics
Aerobic Gram Negative Rod
Family: Pseudomonadaceae
Pseudomonas aeruginosa
Pseudomonas mallei (Glanders)
Gram Negative Rod Aerobic
Family: Legionellaceae
Legionella pneumophila
Legionellaceae
Pathophysiology
Aerobic, intracellular, Gram
negative rod
Virulent organism
More severe disease than
other atypical pneumonia
Transmission
Waterborne
Transmission
Optimal conditions for growth
Temperature: 89 to 113 F
water
Stagnant water
Freshwater or moist soil
near ponds
Air conditioning
Condensers
Cooling towers
Respiratory therapy
equipment
Showers or water faucets
Whirlpools
Incubation
Two to ten days
Legionellaceae
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
Later Symptoms: Cough
Minimal to no sputum
production
Slightly blood tinged
sputum
Signs
Severe respiratory distress
Confusion
Disorientation
Legionella pneumophila
Complications
Respiratory failure (20-40% of cases)
Extrapulmonary complications
Myocarditis/pericarditis
Prosthetic valve endocarditis
Glmoerulonephritis
Pancreatitis
Peritonitis
Legionella pneumophila
Radiology: chest x-ray
Small pleural effusions
Unilateral parenchymal infiltrates
Round, fluffy opacities
Spread contiguously to other lobes
Progresses to dense consolidation
Progresses to bilateral infiltrates
Legionella pneumophila
Labs
CBC
Erythrocyte Sedimentation Rate
leukocytosis
leukopenia
Elevated markedly
LFTs increased
Sputum Exam
Fluorescent antibody studies of sputum
Legionella can not be seen on gram stain
Legionella pneumophila
Diagnosis
Legionella urine antigen testing
High sensitivity/ serogroup 1
Sputum Culture - to ID other serogroups
Serogroup 1 (LP1) causes most U.S. cases
Urine antigen and sputum culture all cases
Legionella Serologies
Legionella fourfold titer rise to >= 1:128 or
Legionella titer >= 1:256
Legionella pneumophila
Management (Antibiotic course for 21
days)
Azithromycin IV
Levofloxacin IV
Trovafloxacin IV
Erythromycin IV
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
Epidemiology
US Incidence
<100 cases per year (0.34/100,000)
Etiology
Brucella abortus
Brucella suis
Brucella melitensis
Brucellosis
Pathophysiology
Facultative intracellular parasite
Releases endotoxin when dies
Infective dose: 10-100 organisms
Incubation: 5-60 days
Brucellosis
Transmission
Infected animal products
Tissue from Sheep in U.S.
Unpasteurized milk
Vaccine exposure
No transmission person to person
Enters via mucus membranes, broken
skin, or inhalation
Brucellosis
Risk Factors
Veterinarians
Farm workers
Meat processing plants
Travel or residence in endemic region
Mediterranean
India
North Africa, East Africa
Central Asia, South Asia
Brucellosis
Symptoms
Intermittent fevers
Undulating fever
Temperature peaks in evening to 101-104
Arthralgia (90%)
Weakness
Lassitude
Weight loss
Headache
Sweating
Chills
Brucellosis
Course
Weeks to months
Prognosis
Case Fatality
<5% treated
Gram Negative Cocci
Aerobes
Moraxella(Branhamella catarrhalis)
Acinetobacter
Neisseria
Neisseriaceae
Neisseria meningitidis
Neisseria gonorroeae
Neisseria gonorrhoeae
Epidemiology
Incidence: 500-700,000 cases per year
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
Incubation: 2-7 days
Neisseria gonorrhoeae
Symptoms and Signs: General
Urinary Symptoms
Copious urethral discharge
Urinary frequency
Urinary urgency
Dysuria
Green, yellow, or sanguinous discharge
Meatus and anterior urethra inflammation
Neisseria gonorrhoeae
Conjunctivitis
Direct inoculation
Copious exudate
Beefy Conjunctiva
Serious complications
Pharyngitis
Corneal ulceration or opacification
Visual loss
Globe perforation
Rarely the only site of infection
Usually asymptomatic
Acute Diarrhea
Neisseria gonorrhoeae
Symptoms and Signs: Women
Mucopurulent Cervicitis
Often asymptomatic
Vaginal d/c or spotting
Bartholin’s Gland inflammation
Skene's gland inflammation
Neisseria gonorrhoeae
Symptoms and Signs: Men (often
asymptomatic)
Epidiymitis under age 35 years
Proctitis
Receptive anal intercourse or vaginal
secretions
Mild anal irritation or itching
Neisseria gonorrhoeae
Symptoms and Signs: Disseminated
Infection
More common in pregnancy
Dermatitis
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
Complications
PID
Systemic Gonorrhea
Chronic Arthritis
Neonatal Gonorrhea
Gonorrheal conjunctivitis
Preterm labor
Neisseria gonorrhoeae
Labs
Gram stain: Urethral /cervical smear
Numerous WBCs
Gram negative biscuit-shaped diplococci
Gonorrhea culture and Sensitivity
Antigen Testing (e.g. Gonozyme)
False positive Gram stain (saprophytic Neisseria)
Indicated in symptomatic men
Inaccurate in other populations
DNA probe testing
Rapid: 30 minutes
Sensitivity: 85-100%
Specificity: 99-100%
Neisseria gonorrhoeae
Management: Drug Resistance
Tetracycline resistance: 17-23%
Penicillin resistance 15-19%
Emerging Fluroquinolone resistance
No resistance to 3rd generation cephalosporins
Ceftriaxone (Rocephin)
Cefixime (Suprax)
Azithromycin requiring higher dosages for some
GC
References
Moraxella catarrhalis
Diagnosis
Represents less than 5% of all pneumonias
More common in COPD
Lobar consolidation is rare
Moraxella catarrhalis
Labs
Gram stain
Kidney bean shaped gram negative diplococci
Radiology
Chest xray
patchy bronchopulmonary
infiltrate
Moraxella catarrhalis
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
Rickettsia
Ehrlichia
Coxiella
Rochalimaea (not obligate intracellular)
Rickettsia
Genus: Rickettsia
Typhus Group
Spotted Fever Group
Rickettsia prowazekii (epidemic typhus,louse)
Rickettsia mooseri
Rickettsia rickettsii (rmsf,tick)
Scrub Typhus Group
Rickettsia tsutsugamushi (scrub typhus,)
Rickettsia rickettsii
Pathophysiology
Transmission: Tick bite
Infects blood vessel walls
Endothelial cells
Smooth muscle cells
Rickettsia rickettsii is causative organism
Small pleomorphic organism
Obligate intracellular parasite
Rocky Mountain Spotted Fever
Epidemiology
Bimodal age distribution
Ages 5 to 9 years old
Age over 60 years old
Endemic area
North America
Atlantic coast states
Midwest
Central America
South America
Rocky Mountain Spotted Fever
Symptoms (follows seven day
incubation)
Fever
HA
Myalgias
Malaise
vomiting
Rocky Mountain Spotted Fever
Signs: Rash (occurs in 90% of patients)
Onset in first week of illness
Characteristics
Distribution
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
Labs
CBC
Liver transaminases increased
AST /ALT
Serum sodium -Hyponatremia
Cerebrospinal Fluid
WBC normal or slightly decreased
Thrombocytopenia
CSF pleocytosis w/monocytic predominance
Rickettsia Serology
Positive 7 to 10 days after symptom onset
Used for confirmation, not for diagnosis
Rocky Mountain Spotted Fever
Management
Antibiotic Course
Minimum course: 5 to 7 days
Continue antibiotics until afebrile for 2 days
Antibiotics
Doxycycline or Tetracycline or
Chloramphenicol
Rocky Mountain Spotted Fever
Complications
Encephalitis
Noncardiac pulmonary edema
ARDS
Cardiac arrhythmia
Coagulopathy
GI bleeding
Skin Necrosis
Rocky Mountain Spotted Fever
Prognosis
Untreated:
25% Mortality within 8 to 15 days
Treated:
5% Mortality
Ehrlichia
Ehrlichia sennetsu
Ehrlichia canis
Coxiella
Coxiella burnetii – Q fever, no arthropod
vector cattle,sheep, goats, inhallation of
dust with dried feces urine or milk
Rochalimaea (not obligate
intracellular)
Rochalimaea quintana (trench fever seen
in military settings)
Chlamydia
Eye Diseases
Trachoma
Inclusion conjunctivitis
Genitourinary Disease
Lymphogranulmoa
venereum
Urethritis
cervicitis
Salpingitis
Respiratory
Other
Chlamydia psittaci
(Human psittacosis)
Chlamydia pneumonia in
newborns
Bird borne zoonosis
Respiratory illness or
typhoidal illness
Chlamydia pneumoniae
pneumonia
Chlamydia trachomatis
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)
Cause
Complications
Chlamydia Trachomatis (obligate intracellular
organism)
PID
Infertility
Preterm labor
Perinatal transmission to newborn
Chlamydia conjunctivitis
Neonatal pneumonia
Chlamydia Trachomatis (obligate
intracellular organism)
Symptoms: Women
Vaginal d/c
dysuria
Pelvic pain
Untreated infections may persist for months
Usually asymptomatic
Urethritis
Dysuria-Sterile pyuria Syndrome
Persistent dysuria and pyuria
Negative urine culture
Chlamydia Trachomatis (obligate
intracellular organism)
Symptoms: Men
Urethritis
Often symptomatic
Associated Conditions: Reiter’s
Syndrome in Men
Arthritis
Conjunctivitis
Urethritis
Chlamydia Trachomatis (obligate
intracellular organism)
Management
First Choice
Refer all sexual contacts for treatment
Azithromycin 1 gram PO for 1 dose
Doxycycline 100 mg PO bid for 7 days
Alternatives
Ofloxacin 300 mg PO bid for 7 days
Erythromycin 500 mg PO qid for 7 days
Erythromycin Ethylsuccinate (EES)
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)
Pregnancy
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)
Erythromycin for 14 days
Questions ??????