Common Bacterial Infections Flashcards by Kelly Humble

Gram positive Bacteria

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

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Gram Negative Bacteria

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

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Staphylococcus sp

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

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Pathogenicity of S. aureus

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 )

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MRSA, Methicillin-resistant Staphylococcus Aureus

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.

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Treatment of MRSA

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

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Cellulitis

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)

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Abscess

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

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Myonecrosis (Gas Gangrene)

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

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Staphylococcal toxins (SSSS)

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

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Streptococcal Infections

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

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Erysipelas Pathogenesis

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)

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Difference Between Cellulitis and Erysipelas

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

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Impetigo (pyoderma)

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)

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Treatment of Impetigo

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

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Long-Term Complications of Group A Infections

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

Beta hemolytic Group B Streptococcus

Normal flora in lower GIT, female genital tract

Pathogenicity: Neonatal meningitis and sepsis, Pneumonia

Streptococcus pneumoniae (pneumococcus)

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

Otitis Media TREATMENT

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

Streptococci viridans (alpha or gamma hemolytic)

Common oral/pharyngeal flora
Infections
Endocarditis
Bacteremia & Septic Shock

Group D streptococci (enterococcus)

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

Gram negative cocci

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

Neisseria gonorrheae

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

N. meningitidis - MeningitisN. gonorrheae - Gonorrhea

Non-motile, Gram negative
Usually diplococci
Aerobic

Fulminant meningeal sepsis (FMS)

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

Meningitis

< 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

The Gram-Negative Bacilli of Medical Importance

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.

facultative anaerobic organism

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.

Pseudomonas: The Pseudomonads

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

Brucella and Brucellosis

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.

coccobacillus

(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.

Francisella tularensis and Tularemia

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

Bordetella pertussis

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

Legionella pneumophila and Legionellosis

``` 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 ```

Pathogenic Strains of E. coli

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

Klebsiella pneumoniae

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

Yersenia Pestis (Plague)

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

Haemophilus

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