Rickettsial Dz’s Of Humans; Typical Bacterial Pneumonias

1. A 36-year-old man in Texas with fever, headache, myalgia, and tick exposure had a serological test that showed antibodies against Ehrlichia chafeeensis. What is a feature of Ehrlichia that differs from other Rickettsia?

Invasion of mononuclear leukocytes

Invasion of vascular endothelium

Cell wall that contains peptidoglycan

Cell wall that contains lipopolysaccharide

Invasion of polymorphonuclear leukocytes

Explanation

2. How are the obligate intracellular pathogens of the genera Rickettsia, Ehrlichia, and Anaplasma transmitted by vectors?

All are transmitted by ticks except for Rickettsia typhi, which is transmitted by lice

Rocky Mountain spotted fever is transmitted mainly by Amblyoma ticks found in Texas

Anaplasma is transmitted mainly by Ixodes ticks, which can be co-infected with Babesia or agent of Lyme disease

Epidemic typhus is transmitted mainly by rodent fleas

Organism-------------------- Disease---------------Vector--------------- Reservoir

Rickettsia rickettsii---------Rocky Mountain------Tick-----------------Dogs, ticks
........................................ spotted fever
Rickettsia typhi--------------Endemic typhus *****Flea***************Rodents
Rickettsia prowazeki-------Epidemic typhus------Louse-----------Humans, flying squirrels

Orientia tsutsugamushi ---Scrub typhus---------Chigger(mite)----- Humans

Ehrlichia chaffeensis-------Ehrlichiosis-------------Tick--------------- Deer, rodents
Anaplasma -------------------Anaplasmosis--------Tick----------------Rodents, deer
phagocytophilum

*Typhus means smoky or hazy in Greek, refers to mental stupor

Explanation

Organism-------------------- Disease---------------Vector--------------- Reservoir

Rickettsia rickettsii---------Rocky Mountain------Tick-----------------Dogs, ticks
........................................ spotted fever
Rickettsia typhi--------------Endemic typhus *****Flea***************Rodents
Rickettsia prowazeki-------Epidemic typhus------Louse-----------Humans, flying squirrels

Orientia tsutsugamushi ---Scrub typhus---------Chigger(mite)----- Humans

Ehrlichia chaffeensis-------Ehrlichiosis-------------Tick--------------- Deer, rodents
Anaplasma -------------------Anaplasmosis--------Tick----------------Rodents, deer
phagocytophilum

*Typhus means smoky or hazy in Greek, refers to mental stupor

3. A 50 year old man diagnosed as having the features of a lobar Pneumonia. Which one of the following symptoms is most indicative of pneumonia?

He had chest pain, cough and difficulty with lying flat in bed at nights

He had fever, hoarseness, a post-nasal drip and a cough

There was fever, left chest pain on breathing, cough, and yellow sputum

He had cough, acute shortness of breath, hemoptysis and left calf pain

On walking that morning he had a wheezy chest, cough and shortness of breath

The symptoms of fever, left chest pain on breathing, cough, and yellow sputum are most indicative of pneumonia. Fever is a common symptom of pneumonia and is often accompanied by chest pain, especially when breathing deeply. Coughing is another common symptom, as the body tries to clear the infection from the lungs. The presence of yellow sputum suggests an infection in the respiratory system, which is consistent with pneumonia. Therefore, these symptoms together are highly suggestive of pneumonia in the given case.

Explanation

The symptoms of fever, left chest pain on breathing, cough, and yellow sputum are most indicative of pneumonia. Fever is a common symptom of pneumonia and is often accompanied by chest pain, especially when breathing deeply. Coughing is another common symptom, as the body tries to clear the infection from the lungs. The presence of yellow sputum suggests an infection in the respiratory system, which is consistent with pneumonia. Therefore, these symptoms together are highly suggestive of pneumonia in the given case.

4. An outbreak of murine (endemic) typhus occurred in the US in 2008. Affected patients experienced fever, headache, chills, vomiting, nausea, myalgia, and rash. Of the 53 cases, 62% had a four-fold rise in antibody titer to Rickettsia typhi antigens. What is the vector associated with transmission of this organism?

Mosquito

Body louse

Tick

Flea

Sand fly

Organism-------------------- Disease---------------Vector--------------- Reservoir

Rickettsia rickettsii---------Rocky Mountain------Tick-----------------Dogs, ticks
........................................ spotted fever
Rickettsia typhi--------------Endemic typhus *****Flea***************Rodents
Rickettsia prowazeki-------Epidemic typhus------Louse-----------Humans, flying squirrels

Orientia tsutsugamushi ---Scrub typhus---------Chigger(mite)----- Humans

Ehrlichia chaffeensis-------Ehrlichiosis-------------Tick--------------- Deer, rodents
Anaplasma -------------------Anaplasmosis--------Tick----------------Rodents, deer
phagocytophilum

*Typhus means smoky or hazy in Greek, refers to mental stupor

Explanation

Organism-------------------- Disease---------------Vector--------------- Reservoir

Rickettsia rickettsii---------Rocky Mountain------Tick-----------------Dogs, ticks
........................................ spotted fever
Rickettsia typhi--------------Endemic typhus *****Flea***************Rodents
Rickettsia prowazeki-------Epidemic typhus------Louse-----------Humans, flying squirrels

Orientia tsutsugamushi ---Scrub typhus---------Chigger(mite)----- Humans

Ehrlichia chaffeensis-------Ehrlichiosis-------------Tick--------------- Deer, rodents
Anaplasma -------------------Anaplasmosis--------Tick----------------Rodents, deer
phagocytophilum

*Typhus means smoky or hazy in Greek, refers to mental stupor

5. A 62-year-old male presented with the sudden onset of shaking chills, cough productive of thick yellow sputum, and dyspnea. The x-ray showed lobar consolidation of the right lower lobe. Sputum culture grew Streptococcus pneumoniae. Which clinical feature of this case of typical pneumonia best differentiates it from atypical pneumonia?

Sudden onset

Thick purulent sputum

Shaking chills

X-ray pattern

Culture result

The presence of thick purulent sputum in this case of pneumonia best differentiates it from atypical pneumonia. Atypical pneumonia is typically characterized by a dry, non-productive cough or a cough that produces clear or white sputum. The presence of thick, yellow sputum suggests a bacterial infection, specifically Streptococcus pneumoniae in this case. This is a characteristic feature of typical pneumonia.

Explanation

The presence of thick purulent sputum in this case of pneumonia best differentiates it from atypical pneumonia. Atypical pneumonia is typically characterized by a dry, non-productive cough or a cough that produces clear or white sputum. The presence of thick, yellow sputum suggests a bacterial infection, specifically Streptococcus pneumoniae in this case. This is a characteristic feature of typical pneumonia.

6. A 23-year-old pregnant woman is admitted to hospital in severe respiratory distress following a week-long influenza-like illness for which she received symptomatic treatment only. A respiratory specimen taken in intensive care shows Gram-negative bacilli. What is the most likely causative agent?

Streptococcus pneumonia

Haemophilus influenzae

Staphylococcus aureus

Klebsiella pneumoniae

Moraxella catarrhalis

The most likely causative agent in this case is Haemophilus influenzae. This is because the patient is experiencing severe respiratory distress following an influenza-like illness, and a respiratory specimen taken shows Gram-negative bacilli. Haemophilus influenzae is a Gram-negative bacillus that commonly causes respiratory tract infections, especially in individuals with compromised immune systems or underlying respiratory conditions. It is known to cause severe respiratory distress and can be a serious complication in pregnant women.

Explanation

The most likely causative agent in this case is Haemophilus influenzae. This is because the patient is experiencing severe respiratory distress following an influenza-like illness, and a respiratory specimen taken shows Gram-negative bacilli. Haemophilus influenzae is a Gram-negative bacillus that commonly causes respiratory tract infections, especially in individuals with compromised immune systems or underlying respiratory conditions. It is known to cause severe respiratory distress and can be a serious complication in pregnant women.

7. An 86-year-old man was admitted to the hospital with a fever and chest x-ray evidence of consolidation and received antibiotics. Two weeks after his initial admission, he was re-admitted to the hospital with fever, a purulent cough, and dyspnea. What organism was likely to have been cultured from sputum during his second illness?

Streptococcus pneumonia

Haemophilus influenza

Staphylococcus epidermidis

Klebsiella pneumonia

Moraxella catarrhalis

During his second illness, the patient presented with symptoms such as fever, purulent cough, and dyspnea. These symptoms are indicative of a lower respiratory tract infection. Klebsiella pneumoniae is a common cause of pneumonia, especially in elderly patients with underlying health conditions. It is known to cause severe pneumonia with symptoms such as productive cough, fever, and difficulty breathing. Therefore, it is likely that Klebsiella pneumoniae would be cultured from the patient's sputum during his second illness.

Explanation

During his second illness, the patient presented with symptoms such as fever, purulent cough, and dyspnea. These symptoms are indicative of a lower respiratory tract infection. Klebsiella pneumoniae is a common cause of pneumonia, especially in elderly patients with underlying health conditions. It is known to cause severe pneumonia with symptoms such as productive cough, fever, and difficulty breathing. Therefore, it is likely that Klebsiella pneumoniae would be cultured from the patient's sputum during his second illness.