Archive for October 2020

How is pseudomembranous colitis treated?

How is pseudomembranous colitis treated?


Answer: Discontinue offending drug and start metronidazole or vancomycin. Both suppress C. difficile and allow normal flora to return.


What commonly causes pseudomembranous colitis?

What commonly causes pseudomembranous colitis?



Answer: Usage of broad-spectrum antibiotic treatment (eg, clindamycin or ampicillin) results in suppression of normal GI flora and proliferation of C. difficile. Clostridium difficile is usually acquired from the hospital environment.


How is botulism treated?

How is botulism treated?



Answer: Classic botulism can be treated with respiratory care and antitoxin; as for infant botulism, infants typically recover spontaneously with supportive care.


CLOSTRIDIUM DIFFICILE Name the most common disease associated with Clostridium difficile:

Pseudomembranous colitis


What are the symptoms of classic botulism?

What are the symptoms of classic botulism?



Answer: Cranial paralysis, including diplopia, ptosis, dysphagia, symmetric, descending motor paralysis, and death due to respiratory failure


Mnemonic:

BAFfles nerves (Botulism, Ach, Flaccid paralysis)


What usually causes infant botulism? What are its associated symptoms?

What usually causes infant botulism? What are its associated symptoms?



Answer: Results from infant ingestion of contaminated honey leading to lethargy, and decreased muscle tone, floppy baby syndrome; most common type of botulism in the United States


What diseases does C. botulinum cause?

What diseases does C. botulinum cause?



Answer: Clostridium botulinum causes food-borne botulism (ingestion of preformed toxin), infant botulism (ingestion of spores that germinate in gut-producing toxins), and wound botulism (injection of spores that germinate in tissue-producing toxins).


How is B. cereus treated?

How is B. cereus treated?



Answer: The food poisoning is self-limited, so it is treated with supportive care to prevent dehydration.

What are the clinical symptoms caused by the heat-labile and heat-stable toxins?

What are the clinical symptoms caused by the heat-labile and heat-stable toxins?



Answer: Rapid onset (<5 hours) of vomiting and nausea following ingestion of food is classic for heat-stable toxin. Onset of voluminous, watery, nonbloody diarrhea, nausea, vomiting, and abdominal pain after an incubation period up to 16 hours is characteristic of heat-labile toxin.


Name the gram-negative rod that produces a toxin similar to the heat-labile toxin of B. cereus. What are their mechanisms of action?

Name the gram-negative rod that produces a toxin similar to the heat-labile toxin of B. cereus. What are their mechanisms of action?



Answer: Vibrio choleras cholera toxin. Both toxins trigger adenosine diphosphate (ADP)-ribosylation of G protein, stimulating adenylate cyclase and increasing cAMP. (ADP-ribosylation is a common mechanism used by various bacterial toxins.)


How is anthrax usually treated?

How is anthrax usually treated?



Answer: Penicillin, tetracyclines, and fluoro-quinolones (remember the rush to get ciprofloxacin during the anthrax terrorism crisis)


What are the clinical symptoms of pulmonary anthrax? What is the overall mortality rate?

What are the clinical symptoms of pulmonary anthrax? What is the overall mortality rate?



Answer: First stage (first 2-3 days) consists of influenza-like symptoms such as dry cough, fever, and aches. Then sudden progression to second stage, which is characterized by difficulty breathing, substernal pressure due to bloody pleural effusion, and sepsis. Chest x-ray shows widening of the mediastinum. Mortality rate near 100% if untreated.


Name the three virulence factors of B. anthracis and describe their mechanism of action:

Name the three virulence factors of B. anthracis and describe their mechanism of action:



1. Capsule is antiphagocytic.

2. Edema factor exotoxin is acalmodulin-dependent adenylate cyclase that increases cyclic adenosine monophos-phate (cAMP) causing severe edema. 3. Lethal factor exotoxin is a protease, causing cells to increase tumor necrosis factor (TNF) production leading to cell death.


BACILLUS ANTHRACIS Name three pathologic manifestations of Bacillus anthracis and their routes of transmission:

BACILLUS ANTHRACIS Name three pathologic manifestations of Bacillus anthracis and their routes of transmission:



1. Cutaneous anthrax by contact with animal products contaminated with spores

2. Pulmonary anthrax (or woolsorter's disease) by direct inhalation of spores

3. Gastrointestinal anthrax by indigestion of contaminated meat


Mnemonic:

Pathogenic Spores Germinate (Pulmonary, Skin [cutaneous], gastrointestinal [GI])

A 55-year-old woman develops Janeway lesions, Osler nodes, splinter hemorrhages, and Roth spots about 1 month after a tooth extraction. She has a history of rheumatic heart disease. What is the most common causative microbe?

A 55-year-old woman develops Janeway lesions, Osler nodes, splinter hemorrhages, and Roth spots about 1 month after a tooth extraction. She has a history of rheumatic heart disease. What is the most common causative microbe?


Answer: This patient has infective endocarditis. Viridans group Streptococcus is the most common cause of subacute infective endocarditis, while S. aureus is the most common cause of acute infective endocarditis.


A boy presents with sore throat, arthralgias, headache, and fever. On examination, his tonsils are enlarged, erythematous, and covered with white exudates. He also has tender cervical lymphadenopathy. You diagnose the patient with pharyngitis and swab his throat to look for what organism on culture? What are two feared complications from this infection?

A boy presents with sore throat, arthralgias, headache, and fever. On examination, his tonsils are enlarged, erythematous, and covered with white exudates. He also has tender cervical lymphadenopathy. You diagnose the patient with pharyngitis and swab his throat to look for what organism on culture? What are two feared complications from this infection?



Group A streptococci (S. pyogenes)

1. Poststreptococcal glomerulonephritis

2. Rheumatic fever

A child presents with a rash that is diffusely erythematous, with superimposed fine red papules, and is most pronounced in the groin and axilla. His face is notably flushed and he has strawberry tongue (enlarged red papillae coating the tongue). Prior to the rash, he had a sore throat. What is your presumed diagnosis?

A child presents with a rash that is diffusely erythematous, with superimposed fine red papules, and is most pronounced in the groin and axilla. His face is notably flushed and he has strawberry tongue (enlarged red papillae coating the tongue). Prior to the rash, he had a sore throat. What is your presumed diagnosis?



Answer: Scarlet fever caused by erythrogenic toxin of S. pyogenes

A 3-month-old male infant presents with extensive bullae and areas of denuded skin, with the epidermis easily dislodging under pressure. His mother had a recent bacterial infection. What is the diagnosis and causative organism?

A 3-month-old male infant presents with extensive bullae and areas of denuded skin, with the epidermis easily dislodging under pressure. His mother had a recent bacterial infection. What is the diagnosis and causative organism?


Answer: Scalded skin syndrome caused by staphylococcal exotoxin

A preschooler presents with a superficial skin infection characterized by erythema with pustules and a honey-colored crust. There are areas of superficial bullae, and some have ruptured leaving raw exudative areas. What is the diagnosis and what are the causative organisms?

A preschooler presents with a superficial skin infection characterized by erythema with pustules and a honey-colored crust. There are areas of superficial bullae, and some have ruptured leaving raw exudative areas. What is the diagnosis and what are the causative organisms?



Answer: Impetigo. Staphylococcus aureus more commonly than group A Streptococcus

A previously healthy young woman was admitted to the intensive care unit (ICU) with high fever, hypotension, nausea, vomiting, disseminated sunburn-like rash, generalized muscle ache, and imminent cardiac and renal failure. Her last menstrual period was about 5 days ago. What is the most likely diagnosis?

A previously healthy young woman was admitted to the intensive care unit (ICU) with high fever, hypotension, nausea, vomiting, disseminated sunburn-like rash, generalized muscle ache, and imminent cardiac and renal failure. Her last menstrual period was about 5 days ago. What is the most likely diagnosis?



Answer: Toxic shock syndrome, most likely secondary to S. aureus from tampon use


Who should receive the S. pneumoniae vaccine?

Who should receive the S. pneumoniae vaccine?



Answer: Older patients (>65), immunocompro-mised patients, diabetics, asplenic patients, and chronic obstructive pulmonary disease (COPD) patients


How is S. pneumoniae treated?

How is S. pneumoniae treated?



Answer: Penicillin is the drug of choice although, penicillin resistance is increasingly prevalent by virtue of altered penicillin-binding proteins.


What is the clinical significance of the IgA protease?

What is the clinical significance of the IgA protease?


Answer: IgA protease allows for infection of the respiratory tract, leading to sinusitis and lobar pneumonia (with characteristic "rusty-colored" sputum).


What is the clinical significance of the polysaccharide capsule?

What is the clinical significance of the polysaccharide capsule?



Answer: It is antiphagocytic, antibodies to the capsule are protective (S. pneumoniae vaccine). Asplenic patients (associated with decreased opsonin antibody production) are more susceptible to severe S. pneumoniae infections.


What diseases do S. pneumoniae cause?

What diseases do S. pneumoniae cause?


Answer: Pneumonia, meningitis (most common cause of bacterial meningitis in adults), otitis media (most common cause in children), sepsis, and sinusitis

What are the viridans group streptococci and where are they normally found?

What are the viridans group streptococci and where are they normally found?



Answer: Human gastrointestinal tract flora. They are normally found in the nasopharynx and gingival crevices. Usually associated with dental infections (Streptococcus mutans), subacute bacterial endocarditis (heart valve destruction), and abscesses (Streptococcus intermedius group). Order a CT scan with contrast to detect an abscess in the body if S. intermedius is extracted from the blood.


What diseases are associated with group B streptococci or S. agalactiae?

What diseases are associated with group B streptococci or S. agalactiae?


Answer: Sepsis and meningitis in neonates and UTIs (some women may have vaginal colonization by S. agalactiae and infect the baby during vaginal delivery), soft tissue, and endocarditis infections in adults

What is scarlet fever?

What is scarlet fever?


Answer: Erythrogenic toxin-mediated disease that develops in association with infections of certain strains of S. pyogenes and is characterized by a coarse, erythematous, blanching rash; a strawberry tongue; petechial lesions in skin creases (Pastia sign); and desquamation of the skin. The erythrogenic toxin is acquired by lysogenic conversion.

What is poststreptococcal acute glomerulonephritis (AGN)?

What is poststreptococcal acute glomerulonephritis (AGN)?



Answer: Immunologic disease caused by deposited antigen-antibody complexes onto the glomerular basement membrane leading to glomerular destruction. Clinically it presents 2 to 3 weeks after S. pyogenes cellulitis or pharyngitis with hypertension, edema, and urine with RBC casts, oliguria, and azotemia.


Where is the most frequent damaged site of the heart as a result of recurrent infections with streptococci?

Where is the most frequent damaged site of the heart as a result of recurrent infections with streptococci?



Mitral valve is the most common site followed by the aortic valve. The damaged valve may be apparent after many years as a heart murmur on physical examination. Prolonged penicillin therapy for prophylaxis is required to prevent future infections with S. pyogenes. Once heart valves are damaged, patients should be given amoxicillin before any dental or surgical procedure.


How is rheumatic fever diagnosed?

How is rheumatic fever diagnosed?


Answer: Using the modified Jones criteria, which require two major criteria (carditis, migratory polyarthritis, subcutaneous nodules, erythema marginatum, chorea) or one major plus two minor criteria (pervious history of acute rheumatic fever, elevated C-reactive protein, ASO titer)


What is rheumatic fever?

What is rheumatic fever?



Answer: Immunologic disease caused by cross-reactivity of S. pyogenes M protein and antigens of joint and heart tissue. Clinically it presents 2 to 3 weeks following S. pyogenes pharyngitis (strep throat) and manifests with fever, migratory arthritis, chorea (rapid purposeless movements), carditis (new-onset murmur), subcutaneous nodules, and erythema marginatum (rash with pale centers and red margins).


Mnemonic:

ACCNE= migratory Arthritis, Chorea, Carditis, subcutaneous Nodules, Erythema marginatum


What is necrotizing fasciitis and how is it treated?

What is necrotizing fasciitis and how is it treated?



Answer: Very serious subcutaneous infection that spreads rapidly along fascial plane typically after trauma of the skin. Can be either polymicrobial or monomi-crobial (classically S. pyogenes). Treat with aggressive surgical debridement (including amputation) and antibiotics active against the likely pathogens. (If group A Streptococcus, use penicillin and clindamycin.)

How is Streptococcus impetigo differentiated from Staphylococcus impetigo? Why is it always important to treat Streptococcus impetigo?

How is Streptococcus impetigo differentiated from Staphylococcus impetigo? Why is it always important to treat Streptococcus impetigo?



Answer: Streptococcus impetigo manifests with vesicles not bullae (although this is difficult to differentiate clinically). Glomerulonephritis may develop secondary to untreated Streptococcus impetigo.


Streptococcus pyogenes causes disease through what three broad pathogenic mechanisms?

Streptococcus pyogenes causes disease through what three broad pathogenic mechanisms?



1. Pyogenic inflammation (pharyngitis and cellulitis)

2. Toxin-mediated diseases (scarlet fever, toxic shock syndrome)

3. Immunologic diseases/delayed antibody-mediated diseases (rheumatic fever and glomerulonephritis)


What is M protein?

What is M protein?


Answer: Antiphagocytic virulence factor S. pyogenes. Specific types of M protein are associated with pharyngitis/acute rheumatic fever, cellulitis/acute glomerulonephritis, and necrotizing fasciitis. The body makes antibodies against the M protein.


What virulence factor causes β-hemolysis?

What virulence factor causes β-hemolysis?


Answer: Streptolysin O and S. Streptolysin O is inactivated by oxygen and antistreptolysin O (ASO) antibodies are important in the diagnosis of rheumatic fever. Streptolysin S is oxygen stable and is not immunogenic.


Describe the Lancefield group, type of hemolysis, and key diagnostic features for the following:

Describe the Lancefield group, type of hemolysis, and key diagnostic features for the following:



Streptococcus pyogenes

Lancefield group A, β-hemolytic, bacitracin sensitive


Streptococcus agalactiae

Lancefield group B, α-hemolytic, bacitracin resistant


Enterococcus faecalis and Enterococcus faeciu

Lancefield group D, α- or (3-hemolytic, growth in 6.5% NaCl


Streptococcus bovis

Lancefield group D, α-hemolytic, no growth in 6.5% NaCl


Streptococcus pneumoniae

No Lancefield group, α-hemolytic, bile soluble, inhibited by optochin


Viridans group streptococci

No Lancefield group, α-hemolytic, not bile soluble, not inhibited by optochin


How are Streptococcus species classified?

How are Streptococcus species classified?


Answer: According to Lancefield group (antigen characteristics of the C carbohydrate found on the cell wall) or type of hemolysis


What type of infection is S. saprophyticus associated with?

What type of infection is S. saprophyticus associated with?



Answer: Second most common cause of urinary tract infections (UTIs) in sexually active younger women. Most common is Escherichia Coli.


Mnemonic:

drinking Sapporo and not resisting your novio leads to UTIs


How is methicillin-resistant S. aureus (MRSA) treated?

How is methicillin-resistant S. aureus (MRSA) treated?


Answer: Vancomycin for severe infections. Bactrim, clindamycin, doxycycline for milder infections. Linezolid and daptomycin may also be used as alternatives.


What are other important S. aureus exotoxins and their mechanisms of action? Coagulase

What are other important S. aureus exotoxins and their mechanisms of action? 


Coagulase

Activates clotting around S. aureus, thereby preventing phagocytosis



Staphylokinase

Lyses thrombi and prevents body from "walling-off" an infection


Hyaluronidase

Lyses the connective tissue matrix facilitating spread


Hemolysin and leukocidin

Lyses red blood cells (RBCs) (therefore β-hemolytic) and white blood cells (WBCs)


β-Lactamase

Cleaves penicillin family (ie, β-lactam) drugs


Mnemonic:

Toxins make S. aureus a Body LEECH (TSST, Staphylokinase, β-lactamase, Leukocidin, Enterotoxin, Exfoliatin, Coagulase, and Hemolysin/Hyaluronidase)


What is protein A and where is it found?

What is protein A and where is it found?



Answer: Virulence factor in the cell wall of S. aureus which binds to the Fc portion of immuno-globulin G (IgG), preventing activation of complement, opsonization, and phagocytosis


What type of vaccine is the S. pneumoniae vaccine?

What type of vaccine is the S. pneumoniae vaccine?



There are two types of vaccines available for S. pneumoniae. The first vaccine is composed of 23 polysaccha-rides purified from the capsules of the most important serotypes. This vaccine is indicated for at-risk adults (>65 years old, asplenic) and the antibody levels decrease to prevaccination levels after 10 years. The second vaccine is the 7-valent conjugate vaccine that is recommended for all infants and children.


What type of vaccine is the H. influenzae vaccine?

What type of vaccine is the H. influenzae vaccine?


Answer: It is a conjugated vaccine to diphtheria toxoid against the serotype B (the poly-saccharide capsule in 95% of invasive strains).


What is bacillus Calmette-Guérin (BCG) vaccine?

What is bacillus Calmette-Guérin (BCG) vaccine?


Answer: Live-attenuated Mycobacterium bovis vaccine often used in countries where tuberculosis is endemic. Shown effective for prevention of miliary and meningeal tuberculosis


What are the major disadvantages of killed vaccines?

What are the major disadvantages of killed vaccines?


Answer: Multiple doses must be given; immunity is not lifelong; and adjuvants are often required to further stimulate immune response to the antigens.


What is a killed vaccine?

What is a killed vaccine?


Answer: Killed vaccines contain organisms inactivated by chemical or physical means.


What are the disadvantages of live-attenuated vaccines?

What are the disadvantages of live-attenuated vaccines?


Answer: Reversion to wild-type is a rare but serious complication, especially in immunocompromised patients. Contamination by live organisms or toxins is also a rare but serious consequence.


What are the advantage of live-attenuated vaccines?

What are the advantage of live-attenuated vaccines?


Answer: A single inoculation may lead to lifelong immunity. Mucosal immunity possible with oral administration of some live-attenuated organisms. Increased potential for herd immunity compared with killed vaccines.

Pilots shall be prepared to immediately disengage the autopilot, should any unscheduled ________ be evident. An autopilot lateral malfunction can result in bank angles of _____ deg within ____ sec even though recovery is started approximately ____ sec after the malfunction occurs. A pitch up malfunction could cause a stall within ___ seconds and is therefor considered the most serious autopilot malfunction.

Pilots shall be prepared to immediately disengage the autopilot, should any unscheduled ________ be evident. An autopilot lateral malfunction can result in bank angles of _____ deg within ____ sec even though recovery is started approximately ____ sec after the malfunction occurs. A pitch up malfunction could cause a stall within ___ seconds and is therefor considered the most serious autopilot malfunction.



Answer: control movement; 55; 5; 3; 3

If during a climb all airspeed indicators are determined to be inaccurate, continue max climb thrust and maintain ____ deg of pitch on the ADI for gross weights up to 225K. Maintain ____ deg pitch for gross weights greater than 225K.

If during a climb all airspeed indicators are determined to be inaccurate, continue max climb thrust and maintain ____ deg of pitch on the ADI for gross weights up to 225K. Maintain ____ deg pitch for gross weights greater than 225K.


Answer: 8; 6

To determine which airspeed indicator is most accurate, the aircraft should be flown with wings level so that the speed deviation pointer indicates _______ (0.6 AOA) and the airspeed reading at ).6 AOA should compare with the corresponding airspeed, for the aircraft weight and configuration obtained from the 1-1.

To determine which airspeed indicator is most accurate, the aircraft should be flown with wings level so that the speed deviation pointer indicates _______ (0.6 AOA) and the airspeed reading at ).6 AOA should compare with the corresponding airspeed, for the aircraft weight and configuration obtained from the 1-1.



Answer: "On speed"

If a catastrophic engine failure occurs accompanied by a fire, take prompt action to pull fire switch and discharge extinguishing agent. Failure to accomplish these actions promptly can result in loss of _______ controls due to burned electrical wiring bundle.

If a catastrophic engine failure occurs accompanied by a fire, take prompt action to pull fire switch and discharge extinguishing agent. Failure to accomplish these actions promptly can result in loss of _______ controls due to burned electrical wiring bundle.



Answer: Fire Switch

(Crash Landing) Do not cut the engines prior to touchdown. This would result in a loss after a few seconds of all _________ and all _________ except that still remaining in the accumulators. Loss of hydraulic power will cause the spoilers to blow down after only a few seconds of operation on accumulator pressure. Electrical control of the stabilizer trim will be lost, leaving only manual trim.

(Crash Landing) Do not cut the engines prior to touchdown. This would result in a loss after a few seconds of all _________ and all _________ except that still remaining in the accumulators. Loss of hydraulic power will cause the spoilers to blow down after only a few seconds of operation on accumulator pressure. Electrical control of the stabilizer trim will be lost, leaving only manual trim.



Answer: primary electrical power; hydraulic pressure

(Crash Landing) Extension of the gear for impact is considered beneficial from the stand point of lessening the severity of impact, but not to the extent that an excessive _________ or uncontrollable situation is created. Delay extension If necessary to _________. Prudent judgment must be exercised in determining action to be taken.

(Crash Landing) Extension of the gear for impact is considered beneficial from the stand point of lessening the severity of impact, but not to the extent that an excessive _________ or uncontrollable situation is created. Delay extension If necessary to _________. Prudent judgment must be exercised in determining action to be taken.



Answer: rate of descent; clear obstructions

If the flight director command bars fail during or immediately after takeoff, climb out at recommended ______ climb out (3 engines) or recommended three engine climb out airspeed plus _____ knots (4 engines) with the takeoff flap setting.

If the flight director command bars fail during or immediately after takeoff, climb out at recommended ______ climb out (3 engines) or recommended three engine climb out airspeed plus _____ knots (4 engines) with the takeoff flap setting.



Answer: three engine; 10

Snow and ice accumulation in any significant degree must be removed from the airplane prior to flight. Snow or ice accumulation can increase ______ and adversely affect climb out performance, stalling speed, and handling characteristics. In flight _______ can result from vibrations induced by unremoved accumulations.

Snow and ice accumulation in any significant degree must be removed from the airplane prior to flight. Snow or ice accumulation can increase ______ and adversely affect climb out performance, stalling speed, and handling characteristics. In flight _______ can result from vibrations induced by unremoved accumulations.



Answer: takeoff distance; structural damage

(Engine Fire on Ground) If the fire cannot be extinguished, the pilot will order the airplane abandoned. Ensure the parking brake is set. Pilot will shut down all engines by retarding all throttles to ____. Shutdown APU by setting APU control switches to _____ and/or tripping external power. Turn off the engine starter switches and _______ before leaving the airplane.

(Engine Fire on Ground) If the fire cannot be extinguished, the pilot will order the airplane abandoned. Ensure the parking brake is set. Pilot will shut down all engines by retarding all throttles to ____. Shutdown APU by setting APU control switches to _____ and/or tripping external power. Turn off the engine starter switches and _______ before leaving the airplane.



Answer: Cutoff; stop; Battery power switch

The decision to takeoff or abort should be based on the following considerations" If any emergency or _________ occurs prior to S1, ______ the takeoff. If an emergency occurs after S1 is reached, the takeoff is ________

The decision to takeoff or abort should be based on the following considerations" If any emergency or _________ occurs prior to S1, ______ the takeoff. If an emergency occurs after S1 is reached, the takeoff is ________



Answer: loss of thrust; abort; committed

(APU) If fire cannot be extinguished, the pilot will order the airplane abandoned and ensure the _______ is set. Pilot will shut down all engines by retarding all throttles to _______. Shut down the APU by setting APU control switch to _____ and/or trip external power. Turn off ________ switches and ________ switch before leaving the airplane.

(APU) If fire cannot be extinguished, the pilot will order the airplane abandoned and ensure the _______ is set. Pilot will shut down all engines by retarding all throttles to _______. Shut down the APU by setting APU control switch to _____ and/or trip external power. Turn off ________ switches and ________ switch before leaving the airplane.


Answer: Parking brake; cutoff; stop; engine starter; battery power

The boldface for abort:

The boldface for abort:



Answer: Throttles - Idle; Brakes - Apply; Speed Brakes - 60 Degrees

Under all conditions, if the throttle is inadvertently retarded to CUTOFF position there will be an _________. Do not reopen the throttle. Introducing unburned fuel into the tailpipe area can create a ____ hazard.

Under all conditions, if the throttle is inadvertently retarded to CUTOFF position there will be an _________. Do not reopen the throttle. Introducing unburned fuel into the tailpipe area can create a ____ hazard.


Answer: Immediate flameout; fire

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