question

Streptococcal Pharyngitis (Caustive Agent)

answer

- Streptococcus Pyogenes
Gram-positive
? hemolytic

question

Streptococcal Pharyngitis
(Symptoms)

answer

Symptoms:
Sore, red throat, with pus and tiny hemorrhages, enlargement and tenderness of lymph nodes in the neck; less frequently, abscess formation involving tonsils; occasionally, rheumatic fever and glomerulonephritis as sequels.

question

Streptococcal Pharyngitis
(Pathogenesis)

answer

–Causes a wide variety of illnesses (due to toxins and exoenzymes)

–Complications of infection can occur during acute illness

question

Streptococcal Pharyngitis
(Epidemiology)

answer

–Spread readily by respiratory droplets
•Especially in range of 2 to 5 feet
–Infect only humans under natural conditions
–Nasal organism spreads more effectively than pharyngeal carriers
–Peak incidence occurs in winter or spring

•Highest in grade school children

question

Streptococcal Pharyngitis
(Prevention)

answer

–No vaccine available
–Adequate ventilation
–Avoid crowds

–Sore throats in presence of fever should be cultured for prompt treatment

question

Streptococcal Pharyngitis
(Treatment)

answer

–Confirmed strep throat treated with 10 days of antibiotics
•Penicillin or erythromycin are drugs of choice

–Eliminates organisms in 90% of cases

question

Common Colds
(Causative Agent)

answer

–30% to 50% caused by rhinovirus
•Non-enveloped

•Single-stranded RNA genome

question

Common Cold
(Pathogenesis)

answer

–Virus attaches to specific receptors on respiratory epithelial cells and multiplies in cells
•Large number of viruses released from infected cells
–Injured cells cause inflammation which stimulates profuse nasal secretion, sneezing and tissue swelling
–Infection is halted by inflammatory response, interferon release and immune response

•Infection can extend to ears, sinuses and lower respiratory tract before stopping

question

Common Cold
(Epidemiology)

answer

–Humans are only source for virus
–Close contact with infected person or secretions usually necessary for transmission
•High concentrations are found in nasal secretions during first 2 or 3 days of it
Young children transmit it easily

question

Common Cold
(Symptom)

answer

Scratchy throat, nasal discharge, malaise, headache, cough

question

Common Cold
(Prevention)

answer

–No vaccine
•Too many different types of rhinovirus

- directed at
•Hand washing
•Keeping hands away from face

•Avoiding crowds during times when colds are prevalent

-Treatment
–Antibiotic therapy is ineffectual
–Certain antiviral medications show promise
•Must be taken at first onset of symptoms
–Treatment with over-the-counter medications may prolong duration due to inhibition of inflammation

question

Pinkeye, Earache and
Sinus Infections
(Causative Agent)

answer

–Haemophilus influenza
•Gram-negative bacillus
–Streptococcus pneumoniae
•Gram-positive diplococci
–Otitis media and sinusitis
•Mycoplasma pneumoniae
•Streptococcus pyogenes
•Staphylococcus aureus

–One-third of cases of otitis media have viral etiology

question

Pinkeye
(Pathogenesis)

answer

–Most likely from airborne respiratory droplets

–Resist destruction by lysozyme

question

Earache
(Pathogenesis)

answer

•Often developing at the time of conjunctivitis diagnosis
•Begins with infection of nasal chamber and nasopharynx

question

Sinus Infection
(Pathogenesis)
((

answer

•Begins with infection of nasopharynx and spreads upwards

•Pathogenesis mechanism much like that of otitis media

question

Pinkeye, Earache and
Sinus Infections
(Epidemiology)

answer

–Carrier rates of H. influenza and
S. pneumoniae can reach 80%
–Epidemics of pinkeye common among school children
•Generally in crowded environments
–Otitis media very common in early childhood
•Older children develop immunity to H. influenza
–Less common cause of earache after age five
–Sinusitis occurs in adults and older children

•Generally due to more developed sinuses

question

Pinkeye
(Prevention and Treatment)

answer

•Prevention is directed towards
–Removal of infected individuals from school or day care
–Hand washing
–Avoid rubbing or touching eyes
–Avoid sharing towels
Treatment is achieved through eyedrops or ointments containing antibacterial medications

question

Earache
(Prevention and Treatment)

answer

•Prevention is directed towards
–Administration of influenza vaccine to infants in day care facilities during “flu” season

•Treatment includes
–Antibiotic therapy

»Amoxicillin

question

Sinus Infection
(Treatment and Prevention)

answer

•There are no proven preventative measures
•Treatment is directed at support care
–Decongestants and antihistamines are generally discouraged

»Ineffective and can be harmful

question

Pneumonia
(Causative agents)

answer

–Streptococcus pnuemoniae
•Gram-positive
•Capsule responsible for virulence
•80 different types of
S. pneumoniae
–Klebsiellapneumoniae
•Gram-negative
•Bacillus
•Encapsulated
–Mycoplasma pneumoniae
•Deformed bacterial lacking cell wall

•Aerobic

question

Pneumonia
(Epidemiology)

answer

–30% of healthy individuals carry encapsulated strain in their throat

•Bacterial rarely reach lung due to mucociliary escalator

question

Whooping Cough
(Causative Agent)

answer

–Bordetella pertussis
•Encapsulated
•Strictly aerobic
•Gram-negative
•Bacillus -> endo spores

•Does not survive long periods outside the host

question

Whooping Cough
(Pathogenesis)

answer

–B. pertussis produces numerous toxic products (A-B toxin)
-B portion attaches to cell surface
-A portion enters cell
»Causes increased mucus formation

»Decreases phagocytic killing

question

Whooping Cough
(Epidemiology)

answer

Spreads via infected respiratory droplets
Most infectious during runny nose period
Number of organisms decrease with onset of cough
Classically disease of infants
Often overlooked as a persistent cold
Fosters transmission

question

Whooping Cough
(Prevention)

answer

–Directed at vaccination of infants
•Prevents disease in 70% of individuals
•Pertussis vaccine combined with diphtheria and tetanus toxoids (DPT)

–Injections given at 6 weeks, 4, 6 and 18 months

question

Whooping Cough
(Treatment)

answer

–Erythromycin is effective at reducing symptoms if given early

–Antibiotic usually eliminates bacteria from respiratory secretions

question

Whooping Cough
(Symptoms)

answer

Violent coughing, vomiting and possible convulsions

question

Tuberculosis
(Causative Agent)

answer

–Mycobacterium tuberculosis
•Gram-positive, bacillus
•Acid fast due
•Slow growing
–Generation time 12 hours or more

•Resists most prevention methods of control

question

Tuberculosis
(Symptoms)

answer

–Chronic illness
–Symptoms include
•Slight fever with night sweats
•Progressive weight loss
•Chronic productive cough

–Sputum often blood streaked

question

Tuberculosis
(Pathogenesis)

answer

–Usually contracted by inhalation of airborne organisms
–Bacteria are taken up by pulmonary macrophages in the lungs then sent to lymph nodes
–Resists destruction within phagocyte

–About 2 weeks post infection intense immune reaction occurs

question

Tuberculosis
(Epidemiology)

answer

–Estimated 10 million Americans infected
•Rate highest among non-white, elderly poor people
–Small infecting dose
•ID 10 (inhaled)
–Factors important in transmission

•Frequency of coughing, adequacy of ventilation, degree of crowding

question

Tuberculosis
(Prevention)

answer

–Vaccination widely used in many parts of the world

•Vaccine not given in US because it eliminates use of a test as diagnostic tool

question

Tuberculosis
(Treatment)

answer

–Antibiotic treatment is given in active cases
•Two or more medications are given together to reduce potential antimicrobial resistance
•Antimicrobials include
–Rifampin and Isoniazid (INH)
•Therapy is prolonged

–Lasting at least 6 months

question

Influenza
(Causative Agent)

answer

–Influenza A virus
•Single-stranded RNA genome
–Genome divided into 8 segments
•Spiked envelope
–H spike – hemagglutinin
»Aids in attachment
»N spikes – neuraminidase

»Aids in viral spread

question

Influenza
(Pathogenesis)

answer

–Acquired through inhalation of infected respiratory secretions
–Infected cells die and slough off
•Destroy mucociliary escalator
–Host immunity quickly controls viral spread

–Small number of people die from it

question

Influenza
(Epidemiology)

answer

–Outbreaks occur in United States every year
•Associated with 10,000 to 40,000 deaths
–Pandemics occur periodically
•Most “famous” pandemic of 1918
–Spanned the globe in 9 months

•Pandemics have higher than normal morbidity

question

Influenza
(Prevention and Treatment)

answer

–Vaccine can be 80% to 90% effective
–New vaccine required every year
•Due to antigenic drift
•Antiviral medications are 70% to 90% effective
•Must be taken early

•Not a substitute for vaccine

question

Rocky Mountain Spotted Fever
(Symptoms)

answer

–Distinguished by initial rash of faint pink spots
•Appears first on palms, wrists, ankles and soles of feet

–Rash becomes raised and hemorrhagic, eventually spreads to other parts of the body

question

Rocky Mountain Spotted Fever
(Causative Agent)

answer

–Rickettsia rickettsii
–Obligate, intracellular bacterium
•Requires host organism for survival
–Gram-negative, non-motile, coccobacillus -> endospores

•Bacteria are very small and often difficult to see in gram stain

question

Rocky Mountain Spotted Fever
(Pathogenesis)

answer

–Disease acquired from bite of a tick infected with R. rickettsii
–Bacteria are released into blood and taken up by cells lining vessels
–Bacteria enter cells through endocytosis
•After endocytosis, cell leaves protective phagosome
–Bacterial endotoxin released in bloodstream can cause disseminated intravascular coagulation

•This is recognized by shock and generalized bleeding

question

Rocky Mountain Spotted Fever
(Epidemiology)

answer

- A zoonosis transmitted by bite of infected tick, usually Dermacentor sp.

question

Rocky Mountain Spotted Fever
(Prevention)

answer

Avoidance of tick-infested areas, use of tick repellent, removal of ticks within 4 hrs of exposure

question

Rocky Mountain Spotted Fever
(Treatment)

answer

Doxycycline or Chloramphenicol

question

Lyme Disease
(Symptoms)

answer

–First Stage
•Characterized by skin rash that enlarges
•Other influenza-like symptoms can occur
–Later Stages

•Heart and nervous system impairment can occur

question

Lyme Disease
(Causative Agent)

answer

–Bacterium called Borreliaburgdorferi
–Large microaerophilic spirochete
Borrelia genome is linear and has numerous copies

question

Lyme Disease
(Epidemiology)

answer

Spread by the bite of ticks, lxodes sp., usually found iin association with animals such as white-footed mice and white-tailed deer living in wooded areas

question

Lyme Disease
(Pathogenesis)

answer

Spirochetes injected into the skin by an infected tick multiply and spread radially; the spirochetes enter the bloodstream and are carred throughout the body; the immune reaction to bacterial antigen causes tissue damage.

question

Lyme Disease
(Prevention)

answer

Protective clothing; tick repellents.

question

Lyme Disease
(Treatment)

answer

Doxycycline and others; prolonged antibiotic therapy in chronic cases

question

Cheeeeeekin Pox
(Causitive Agent)

answer

Varicella-zoster virus; enveloped double-stranded DNA virus of the herpesvirus family

question

Cheeeeeekin Pox
(Symptoms)

answer

–Skin rash appears on back of head, face and mouth
•Rash progresses from red spots called macules to small bumps called papuales to small blisters called vesicles to pus filled blisters called pustules
•Lesions itch and appear at different times

•Healing begins after pustules break and crust over

question

Cheeeeeekin Pox
(Epidemiology)

answer

–Annual incidence once estimated in the several millions but declined due to vaccine
–Disease transmitted by respiratory secretions and skin lesions
–Incidences increase in winter and spring
–Viral incubation period approximately 2 weeks

•Infective 1 to 2 days before rash until blisters crust over

question

Cheeeeeekin Pox
(Pathogenesis)

answer

Upper respiratory viurs multiplication followed by dissemination via bloodstream to the skin; cytopathic effect of virus includes the formation of giant cells

question

Measles
(Symptoms)

answer

–Begins with fever, runny nose, cough, red weepy eyes
–Fine rash appears within a few days
–Symptoms generally disappear within 1 week
–Many cases complicated by secondary infections

•Pneumonia and earaches are most common secondary conditions

question

Measles
(Causative Agent)

answer

Rubeola virus, a single-stranded RNA virus of the paramyxovirus family

question

Measles
(Prevention and Treatment)

answer

Attenuated virus vaccine after age 12 months; second dose upon entering elementary school or at adolescence. No antiviral treatement available at present.

question

Measles
(Pathogenesis)

answer

–Infection via respiratory route
–Virus replicates in epithelium of upper respiratory tract
–Spreads to lymph nodes then to all parts of the body

–Infected mucous membranes important diagnostic sign

question

Measles
(Epidemiology)

answer

–Humans are only natural host
–Outbreaks still occur and are due to non- immune populations
–Virus spread by respiratory droplets
•Before routine immunization, over 99% of population infected
•Vaccine resulted in decline of annual cases

– no longer endemic in United States

question

German Measles
(Pathogenesis)

answer

–Enters body via respiratory route
–Virus multiplies in nasopharynx, then enters bloodstream
–Blood transports virus to body tissues

–Immunity develops against viral antigens

question

German Measles
(Epidemiology)

answer

–Humans are only natural host
–Disease is highly contagious
•Less so than measles (rubeola)
–40% of infected people fail to develop symptoms
•These individuals can spread virus

–Infectious 7 days before appearance of rash to 7 days after

question

German Measles
(Causative Agent)

answer

Rubella virus, an RNA virus of the togavirus family

question

German Measles
(Symptoms)

answer

Mild fever and cold symptoms, rash beginning on forehead and face, enlarged lymph nodes behind the ears

question

German Measles
(Prevention and Treatment)

answer

Attenuated rubella virus vaccine administered to children at 12-16 months, repeated at 4-6 yrs of age. No specific antiviral treatment.

question

Tetanus
(Causative Agent)

answer

–Clostridium tetini
•Anaerobic
•Gram-negative
•Bacillus -> endospores
•Spore former
•Swarming growth on laboratory media

question

Tetanus
(Pathogenesis)

answer

–Colonization is generally contained to wound
–Bacteria produce toxin
–Toxin composed of two chains
•Heavy chain binds receptors on motor neuron
•Lighter chain taken up through endocytosis
–Toxin blocks inhibition of motor neurons, causing paralysis

•Muscle contraction is uncontrolled

question

Tetanus
(Symptoms)

answer

–Divided into early and late symptoms
–Early symptoms
•Restlessness
•Irritability
•Difficulty swallowing
•Contraction of jaw muscles
•Convulsions
Particularly in children

–Later symptoms
•Increased muscle involvement
•Pain
•Difficulty breathing

•Death

question

Tetanus
(Epidemiology)

answer

–C. tetani found in dirt and dust and GI tract of humans and animals
–Nearly half of infections result from puncture wounds including
•Body piercing, tattooing, animal bites, injected drug abuse
–30 to 60 cases in United States annually with 25% mortality rate

–Immunization has decreased incidences in economically advanced countries

question

Tetanus
(Prevention)

answer

–Immunization best preventative
•Vaccine is inactivated tetanospasmin

–Given in combination with diphtheria and pertusis vaccine – DPT

question

Tetanus
(Treatment)

answer

–Thoroughly clean wound
•Remove all dead tissue
–Antimicrobial treatment given to kill multiplying bacteria
Metronidazole
Antimicrobials do not kill endospores
Antitoxin - antibody against tetanospasmin

•Neutralizes toxin not attached to nerve cells

question

Gas Gangrene
(Symptoms)

answer

Severe pain, gas and fluid seep from wound, blackening of overlying skin; shock and death commonly follow

question

Gas Gangrene
(Causative Agent)

answer

Usually Clostridium perfringens; other clostridia less frequently

question

Gas Gangrene
(Pathogenesis)

answer

Organism grows in dead and poorly oxygenated tissue and releases a-toxin; toxin kills leukocytes and normal tissue cells by degrading the lecithin component of their cell membranes; invlovement of muscle causes shock by unknown mechanism.

question

Gas Gangrene
(Epidemiology)

answer

Wounds of war; dirt contamination of wounds, tissue death, impaired circulation to tissue as in persons with poor circulation from diabetes and arteriosclerosis; self-induced abortions.

question

Gas Gangrene

answer

Prevention and Treatment

Prompt cleaning and debridement of wounds is preventive; no vaccine available. Treatment: surgical removal of dirt and dead tissues of primary importance; hyperbaric oxygen of possible value; antibiotics to kill vegetative C. perfringens of marginal value.

question

Tomato juice agar

answer

Selective

question

Blood agar

answer

Differential

question

Snyder's agar

answer

differential

question

haemophilus influenza

answer

Gram negative, bacillus (I have no mnemonic for this one)

question

Streptococcus pneumoniae

answer

Gram Positive, diplococci

question

Klebsiellapneumoniae

answer

Gram negative bacillus, capsule
MNEMONIC: double ll's

question

Mycoplasma pneumoniae

answer

Aerobic, lacks cell wall

question

Bordetella pertussis

answer

Gram negative, bacillus, capsule
MNEMONIC: double ll's

question

Mycobacterium tuberculosis

answer

Gram positive bacillus
MNEMONIC: there are t's in it, resembling a + sign; "tube" reminds me of a rod-shaped bacillus

question

Pseudomonas aeruginosa

answer

Gram negative, bacillus
MNEMONIC: no "t" in name, really nasty,thriving on oxygen ruining ppls lives

question

Clostridium tetani

answer

Gram negative, anaerobie
MNEMONIC: bacteria is shaped like a tennis racket, and a minus sign

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