Common Bacterial Infections

Question 1

Gram positive Bacteria

Answer 1

Staphylococcus sp.
Streptococcus sp.
Clostridium Botulinum
Corynebacterium Diptheriae (Diphtheria)
Clostridium Tetanus (Tetanus)
Bacillus antracis (Anthrax)

Question 2

Gram Negative Bacteria

Answer 2

Neisseria sp. (Meningococcal infections)
	Legionnella sp.  (Legionnaire's Disease)
	Brucella sp. (Brucellosis)
	Francisela Tularensis (Tularemia)
	Yersenia Pestis (Plague)
	Chlamydiae sp.
	Lymphogranuloma venereum
	Psittacosis
	Spirochetes
	Relapsing fever
	Lyme disease

Question 3

Staphylococcus sp

Answer 3

Gram Positive
Cocci and form grape-like clusters
Most are harmless and reside normally on the SKIN and MUCOUS membranes.
MRSA: Resistant to beta-lactam antibiotics

Question 4

Pathogenicity of S. aureus

Answer 4

Cutaneous infections –
Folliculitis (boils), furuncle, burns and wounds

Deep infections –
Osteomyelitis, abscesses, pneumonia, endocarditis, septicemia

Toxin mediated infections –
Staphylococcal scalded skin syndrome (SSSS),
Toxic Shock Syndrome (TSS),
Food poisoning (in 1-8hr, vomiting ,diarrhea, nausea, self limited )

Question 5

MRSA, Methicillin-resistant Staphylococcus Aureus

Answer 5

Generally start as small red areas that can resemble spider bites, boils, or pimples that can quickly develop into deep, painful abscesses that require surgical draining.

Sometimes will go deeper into the tissue and cause life threatening infections in bones, joints, blood stream, heart valves and lungs.

Question 6

Treatment of MRSA

Answer 6

Culture and Sensitivity (Takes about 3 days to get result)
Septra DS 1 po bid x 10 days
Or…
Doxycycline 100mg 1 po bid x 10 days

Bactroban (Mupirocin) ointment in the nose qd
Full body wash (Rules of 3) (Hibiclens)
3 times a day for 3 days then 3 times a week for 3 weeks

Question 7

Cellulitis

Answer 7

Group A Streptococci
Found in inflammation spreading along tissue lines
Features: Red, swollen, warm to touch, no areas of pus, pain, tenderness

TX: NOT Keflex (Cephalosporin) anymore!!!
BACTRIM (Trimethoprim-sulfamethoxazole) is the drug of choice followed by Clindamyicin (for sulfa allergic) and finally Vancomycin for MRSA
(IV Abx)

Question 8

Abscess

Answer 8

When the tissue in the area of cellulitis turns to pus under the surface of the skin, the collection of pus is termed an “abscess”
The pus in the abscess consists of dead, liquified tissue, billions of white blood cells
The most common bacteria in the abscess is staph
Many other bacteria that can cause abscesses

Question 9

Myonecrosis (Gas Gangrene)

Answer 9

Pure Clostridium perfringens infection
Gas in a gangrenous muscle group
Incubation period of hours to days
Local edema and pain accompanied by fever and tachycardia
Consider Hyperbaric chamber

Question 10

Staphylococcal toxins (SSSS)

Answer 10

also known as Ritter disease, is caused by epidermolytic toxins produced by certain strains of Staphylococci. This toxin is distributed systemically and results in dissolution of keratinocyte attachments in only the upper layer of the epidermis (stratum granulosum).
affects newborns and children.
adults with renal failure are more susceptible

Question 11

Streptococcal Infections

Answer 11

30 species of bacteria
Gram positive cocci in chains
Subdivided by ability to lyse RBC’s
beta hemolysis-complete lysis
alpha hemolysis-partial lysis
gamma hemolysis-no hemolysis

Question 12

Erysipelas Pathogenesis

Answer 12

Acute streptococcus infection of the upper dermis and superficial lymphatics

Streptococcus pyogenes (Beta hemolytic group A Strep)

Red cheeks and nose (can look like cellulitis)

Question 13

Difference Between Cellulitis and Erysipelas

Answer 13

Cellulitis has an ill-defined border that merge smoothly with adjacent skin; usually pinkish to reddish
Erysipelas has an elevated and sharply demarcated border with a fiery-red appearance

Question 14

Impetigo (pyoderma)

Answer 14

superficial lesions that break and form highly contagious crust; often occurs in epidemics in school children; also associated with insect bites, poor hygiene, and crowded living conditions
Bullous and Non Bullous (fluid filled)

Question 15

Treatment of Impetigo

Answer 15

Usually diagnosed by classic presentation
No cultures usually needed
First soak the affected area in warm water or use wet compresses to help remove overlying scabs
Antibiotic Creams or ointments
Bactroban (Mupirocin) AAA tid x 5 days
Fusidic Acid Cream AAA x 7-12 days
Retapamulon ointment bid x 5 days
Consider Septra/Bactrim if has history of MRSA

Question 16

Long-Term Complications of Group A Infections

Answer 16

Rheumatic fever – follows overt or subclinical pharyngitis in children; extensive valve damage possible, arthritis, chorea, fever
Acute glomerulonephritis – nephritis, increased blood pressure, occasionally heart failure; can become chronic leading to kidney failure

Question 17

Beta hemolytic Group B Streptococcus

Answer 17

Normal flora in lower GIT, female genital tract

Pathogenicity: Neonatal meningitis and sepsis, Pneumonia

Question 18

Streptococcus pneumoniae (pneumococcus)

Answer 18

Gram positive cocci in pairs
Pneumonia	
Otitis media
Sinusitis
Meningitis
Prevention:  Vaccination (capsular antigens)
IMMUNIZATION  (core measure)

Question 19

Otitis Media TREATMENT

Answer 19

Amoxicillin: 20-40 mg/kg/day TID for 10-14 days (1st line) or
Augmentin: 45 mg/kg/day BID for 10-14 days
Auralgan: analgesic/adjunct for ear pain 2-4 drops TID

Question 20

Streptococci viridans (alpha or gamma hemolytic)

Answer 20

Common oral/pharyngeal flora
Infections
Endocarditis
Bacteremia & Septic Shock

Question 21

Group D streptococci (enterococcus)

Answer 21

UTI
Endocarditis	  
Intraabdominal infections (abscesses)
Biliary tract Infections
Wound infections

Question 22

Gram negative cocci

Answer 22

Neisseria
Moraxella catarrhalis…..resides in respiratory tract
-tracheobronchitis and pneumonia

Question 23

Neisseria gonorrheae

Answer 23

Gonorrhea may be the most prevalent human bacterial disease
Leading cause of STD in US
>400,000 cases reported yearly
May be over 1 million

Question 24

N. meningitidis - MeningitisN. gonorrheae - Gonorrhea

Answer 24

Non-motile, Gram negative
Usually diplococci
Aerobic

Question 25

Fulminant meningeal sepsis (FMS)

Answer 25

massive and rapid proliferation in bloodstream
blood culture positive, usually also involves meningitis
rapid clinical deterioration
skin lesions appear after 6 - 12 h, easier to recognize disease

Question 26

Meningitis

Answer 26

< bacterial proliferation in the bloodstream
bacterial invasion of meninges, rapid proliferation in CSF
endotoxin-mediated release of inflammatory mediators
release of PMN products contributes to development of meningitis
skin lesions 12 - 18 h after onset, no lesions in 20% of patients

Question 27

The Gram-Negative Bacilli of Medical Importance

Answer 27

Large, diverse group of non-spore-forming bacteria
Wide range of habitats – large intestines (enteric), zoonotic, respiratory, soil, water
Most are not medically important; some are true pathogens, some are opportunists.
All have a lipopolysaccharide outer membrane of cell wall – endotoxin.

Question 28

facultative anaerobic organism

Answer 28

an organism, usually a bacterium, that makes ATP by aerobic respiration if oxygen is present but is also capable of switching to fermentation. In contrast obligate anaerobes die in the presence of oxygen.

Question 29

Pseudomonas: The Pseudomonads

Answer 29

Small Gram-negative rods with a single polar flagellum
Free living primarily in soil, sea water, and fresh water; also colonize plants and animals
Important decomposers and bioremediators
Use aerobic respiration; do not ferment carbohydrates

Question 30

Brucella and Brucellosis

Answer 30

Tiny Gram-negative coccobacilli
2 species: Brucella abortus (cattle), Brucella suis (pigs)

The bacteria can spread to humans if you come in contact with infected meat or the placenta of infected animals, or if you eat or drink unpasteurized milk or cheese.

Question 31

coccobacillus

Answer 31

(plural coccobacilli) is a rod-shaped bacteria. The word coccobacillus reflects an intermediate shape between coccus (spherical) and bacillus (elongated). Coccobacilli rods are so short and wide that they resemble cocci.

Question 32

Francisella tularensis and Tularemia

Answer 32

facultative intracellular coccobacillus
Causes tularemia, a zoonotic disease of mammals endemic to the northern hemisphere, particularly rabbits
Headache, backache, fever, chills, malaise and weakness
Potential bioterrorism agent

Question 33

Bordetella pertussis

Answer 33

Minute, encapsulated coccobacillus
Causes pertussis or whooping cough, a communicable childhood affliction
Often severe, life-threatening complications in babies
Reservoir – apparently healthy carriers
Vaccine – DTaP

Question 34

Legionella pneumophila and Legionellosis

Answer 34

Widely distributed in water
Prevalent in males over 50
Nosocomial disease in elderly patients
Fever, cough, diarrhea, abdominal pain, pneumonia fatality rate of 3-30%
Tx. with Azithromycin

Question 35

Pathogenic Strains of E. coli

Answer 35

Enterotoxigenic E. coli causes severe diarrhea
Enteroinvasive E. coli causes inflammatory disease of the large intestine.
Enteropathogenic E. coli linked to wasting form infantile diarrhea
Enterohemorrhagic E. coli, O157:H7 strain, causes hemorrhagic syndrome and kidney damage

Question 36

Klebsiella pneumoniae

Answer 36

normal inhabitant of respiratory tract, has large capsule, cause of nosocomial pneumonia, meningitis, bacteremia, wound infections and UTIs
Coliform

Question 37

Yersenia Pestis (Plague)

Answer 37

The Black death
Spread by fleas (vector)
Is on the CDC’s list of reemerging diseases.
Percolating in rodent communities
Tiny, Gram-negative rod, unusual bipolar staining and capsules

Question 38

Haemophilus

Answer 38

H. influenzae – acute bacterial meningitis, epiglottitis, otitis media, sinusitis, pneumonia, and bronchitis
subunit vaccine Hib
Tiny Gram-negative rods