Listeria, H ifluenzae, P aeruginosa, M tuberculosis, M pneumoniae

Question 1

Clinical history: A 33-year-old female dairy farmer develops a severe headache and neck stiffness. On physical examination, her temperature is 38.2°C. She has no papilledema. A lumbar puncture is performed, and a Gram stain of the CSF obtained shows many short, gram-positive rods.
What is the most likely causative agent in the case above?

Answer 1

Listeria moncytogenes

Question 2

Listeria appears in animals, skin, food (T/F)

Answer 2

True

Question 3

Epidemics of Listeria are linked to contaminated food (T/F)

Answer 3

True

Question 4

Complications

Answer 4

Meningitis

Question 5

Persons at risk

Answer 5

Pregnant women, infants, elderly

Question 6

L moncytogenes resembles S pneumoniae (gram +ve diplococci)

Answer 6

True

Question 7

CAMP results for L moncytogenes

Answer 7

-Strep B produces CAMP factor (protein) that interacts with S aureus to enhance lysis of RBCs.
Group B strep streaked perpendicular to S aureus streak on blood agar
+ve result: –Arrowhead zone of hemolysis

Question 8

Important diagnostic factor to distinguish S pneumoniae and L moncytogenes

Answer 8

L moncytogenes is catalase positive and all streptococci are catalase negative

Question 9

Motility pattern

Answer 9

Umbrella motions

Question 10

Treatment

Answer 10

Ceftriaxone
Vancomycin
Listeria treatment - add in ampicillin and gentamicin

Question 11

Why is it important to identify if L moncytogenes is the pathogen?

Answer 11

Since Listeria doesn’t respond to usual antibiotic treatment for strep, it is important to identify which it is.

Question 12

Num 1 cause of community acquired meningitis is L moncytogenes, why?

Answer 12

Neurotropism - An ability to invade and live in neural tissue.

Question 13

Virulence factors: L moncytogenes

Answer 13

Facultative anaerobe - because it can survive in cells
Survives digestion
Adheres to host cells
Can replicate in macocrophages so can carry bacteria anywhere and cross placenta.

Question 14

Life cycle: L moncytogenes

Answer 14

Adheres to host cells -> internalize into phagolysosome
Low pH actives O and C = break out of Listeria
Bacteria replicates in cytosol
Creates actin rockets = propelling around cell into cell wall

Question 15

Neonatal effect: L moncytogenes

Answer 15

• Early onset

- -miscarriage, stillbirth, in utero transmission

Question 16

Late onset in babies- Listeriosis

Answer 16

• At/shortly after birth

- Meningitis/ meningoencephalitis

Question 17

A 10-month-old child of a family from Mexico living in Durham was noted by his mother to have a grand mal seizure with shaking of arms and legs by the description given to the EMT. The EMTs found the child limp and unresponsive. In the emergency room the child’s fever was 39.5°C (103.1°F). Blood cultures and lumbar puncture were performed. CSF findings were as follows:

cell count of 4000
95% PMNs
glucose 20mg/dl
protein 125mg/dl.

Gram stain showed PMNs and occasional Gram-negative coccobacillary organisms. The organism grew on chocolate agar but not on sheep blood agar or MacConkey’s agar. What is the most likely organism in this case?

Answer 17

Haemophilus influenzae

Question 18

Hemophilus influenzae is located where?

Answer 18

Nasopharynx of healthy persons

Question 19

Cell morphology - H influenzae

Answer 19

Short, gram negative rods/coccobacillus
Non motile
No flagella/pilli
Fastidious

Question 20

Requirements for growth

Answer 20

X-factor – respiration enzyme

V factor/NAD - oxidation-reduction process

Question 21

H influenzae ranges of effects on humans:

Answer 21

causes meningitis, primary bacteremia, pneumonia, epiglottitis and arthritis.

Non-Capsulatedinfluenzae(Nc-hi) causes otitis media, conjunctivitis and sinusitis

Causes chronic bronchitis in adults

Question 22

Specimen

Answer 22

CSF, Sterile site aspirates, fluids, urine, sputum, Respiratory tract specimens.

Question 23

Diagnosis

Answer 23

Direct:
–Gram -ve, coccobacilli, small rods

Cultivation:
Blood agar - satellitism
Chocolate agar - mucoid colonies

PCR
Done in case of meningitis

Question 24

Treatment

Answer 24

Num 1 treatment
Cephalosporin (good CSF penetration)
Ceftriaxone + Cefotaxme - used in Meningitis and Septicemia
Amoxicillin - oral - otitis media, bronchitis, sinusitis

Question 25

Pseudomonas aeruginosa is opportunistic, why?

Answer 25

It affects immunocompromised persons (Cystic fibrosis)

Question 26

P aeruginosa features

Answer 26

Gram -ve Rod shaped Non spore forming Aerobic

Question 27

P aeruginosa symptoms

Answer 27

Lungs: pneumonia, coughing, congestion Blood: Joint pain, stiffness, fever, chills, fatigue

Question 28

P aeruginosa - virulence factors

Answer 28

Siderophores - iron chelating Flagella - attachment + invasion of tissue Pilli - attachment Exotoxin A - inhibits protein synthesis in host cells Forming hard to remove biofilms - anaerobic

Question 29

P aeruginosa - Transmission

Answer 29

Can be transmitted to a host via fomites, vectors, and hospital workers who are potential carriers for multiply-antibiotic-resistant strains of the pathogen. 

Question 30

Which illness does Klebsiella pneumoniae often cause?

Answer 30

Bacterial pneumonia/lung infection (common)

Question 31

Transmission - K pneumoniae

Answer 31

-When bacteria enters the respiratory tract/spread via hand contact Community acquired pneumonia (rare) - spread via community setting e.g. mall/subway Hospital acquired pneumonia - spread at hospital/nursing home

Question 32

A 52-year-old homeless, alcoholic man had a fever and a cough productive of thick sputum that worsened over several days. His temperature is 38.2°C.   Diffuse crackles are heard at the right lung base.

Answer 32

Klebsiella pneumoniae

Question 33

K pneumoniae features

Answer 33

Gram negative Enteric - occurs in intestines Rod shaped Thick capsule

Question 34

K pneumoniae usually found where?

Answer 34

Nasopharynx | GIT

Question 35

K pneumoniae symptoms

Answer 35

``` Fever Chills Coughing Yellow/bloody mucus Shortness of breath Chest pain ```

Question 36

Illnesses caused by K pneuminae

Answer 36

Urinary tract, nosocomial pneumonia and intraabdominal infections

Question 37

A 4-year-old female had a gradual onset of fever, productive cough, anorexia and diarrhea about eleven days prior to death. The breath sounds were harsh, and a few cracking rales were heard over the right base posteriorly.

Answer 37

Mycoplasma tuberculosis

Question 38

Where does Mycobacterium tuberculosis usually affect?

Answer 38

Lungs | However, can attack any part of the body such as the kidney, spine, and brain.

Question 39

Mycobacterium is not acid fast (T/F)

Answer 39

False; have ropelike structures of peptidoglycan that are arranged in such a way to give them properties of an acid fast bacteria.

Question 40

Lab ID - M tuberculosis

Answer 40

Slow growth - tough cell wall that prevents passage of nutrients Specimen - sputum Test - acid fast stain

Question 41

Treatment -TB

Answer 41

The most common treatment for active TB is isoniazid INH in combination with three other drugs—rifampin, pyrazinamide and ethambutol.

Question 42

Community acquired atypical pneumonia can be caused by which of the following organisms? ``` Legionella pneumophilia Staphylococcus aureus Klebsiella pneumoniae Mycoplasma pneumoniae Pseudomonas aeruginosa ```

Answer 42

Mycoplasma pneuminae

Question 43

Mycoplasma pneumoniae commonly causes mild infections of the respiratory system (T/F)

Answer 43

True

Question 44

M pneumoniae are bacteria that lack a cell wall, so they require residence in a host organism (T/F)

Answer 44

True; obtain all essential nutrients to survive via mucosal epithelial cells of the host.

Question 45

Transmission

Answer 45

Respiratory droplets

Question 46

Illnesses caused by M pneumoniae

Answer 46

Tracheobronchitis and primary atypical pneumonia

Question 47

Features - M pneumoniae

Answer 47

Spherical, no cell wall, filamentous

Question 48

Virulence factors - M pneumoniae

Answer 48

Adhesion proteins - attachment to epithelial cells of respiratory tract β-lactam antibiotics (ie. penicillin) can’t be used to kill the bacteria, because they target the lyses of the cell wall