Bacteriology Quiz: Haemophilus and Neisseria

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Questions and Answers

What must be done first if there is true increased ICP due to meningococcemia?

Initiate antibiotic therapy

Perform a blood transfusion

Administer corticosteroids

Medically decompress with a lumbar tap (correct)

What syndrome is characterized by bilateral adrenal hemorrhage and may lead to adrenal necrosis?

Reye syndrome

Kawasaki syndrome

Waterhouse-Friderichsen syndrome (correct)

Graves' disease

Which of the following is a complication of meningococcal meningitis?

Renal failure

Severe headache and vomiting (correct)

Ischemic stroke

Pulmonary edema

What is a common early symptom of meningococcemia?

Nonspecific viral illness symptoms Signup and view all the answers

What condition is indicated by raised/increased opening ICP in fulminant meningococcemia?

Cerebral edema Signup and view all the answers

What does disseminated intravascular coagulation cause in patients with meningococcemia?

Severe bleeding and thrombosis Signup and view all the answers

What is a critical consequence of endothelial injury in meningococcal septicemia?

Hypotension and hypovolemia Signup and view all the answers

What can happen in fulminant cases of meningococcemia?

Death within hours of initial symptoms Signup and view all the answers

What risks are associated with monocytogenes in neonates?

Increased risk of vertical transmission and early-onset disease Signup and view all the answers

Which of the following is commonly implicated in mild gastroenteritis caused by monocytogenes in adults?

Pre-prepared fruit or vegetable salads Signup and view all the answers

What clinical manifestation is often noted in patients with altered mental status from meningococcemia?

Confusion and lethargy Signup and view all the answers

What therapeutic procedure may need to be performed daily in cases of fulminant meningococcemia?

Therapeutic lumbar tap Signup and view all the answers

What is a key characteristic of monocytogenes when cultured on 5% sheep blood agar?

Small zone of hemolysis around and under the colonies Signup and view all the answers

What notable antigenic structure is associated with monocytogenes?

Internalins A and B Signup and view all the answers

What does listeriolysin O (LLO) do in the context of monocytogenes infection?

Mediates the rupture of the phagosomal membrane Signup and view all the answers

What complication can monocytogenes cause during pregnancy?

Premature birth and stillbirth Signup and view all the answers

Which serotype of influenzae is considered the most invasive?

Serotype B Signup and view all the answers

What is the composition of the capsule in serotype B?

Polyribitol phosphate Signup and view all the answers

What are the growth factor requirements for the bacteria discussed?

X and V factors Signup and view all the answers

Which test is key for identifying Neisseria?

Oxidase test Signup and view all the answers

What type of bacterium is influenzae classified as based on its oxygen requirements?

Facultatively anaerobic Signup and view all the answers

What type of capsule does the influenzae bacterium have?

Polysaccharide capsule Signup and view all the answers

Which of the following statements is true regarding the growth of the bacteria?

They grow best at 5-10% CO2 Signup and view all the answers

What is the typical duration of treatment for the infection caused by this bacterium?

7-10 days Signup and view all the answers

What characteristic coloration is associated with the morphology of this bacterium?

Gram-negative coccobacillary Signup and view all the answers

Which carbohydrate does meningitidis ferment?

Glucose and maltose Signup and view all the answers

What is the drug of choice for treating meningococcal infections?

Penicillin G Signup and view all the answers

Which method is recommended for post-exposure prophylaxis for meningococcemia?

Ciprofloxacin Signup and view all the answers

What laboratory test is used for the detection of meningococcal antigens?

Latex agglutination Signup and view all the answers

What is the primary prevention method recommended for high-risk groups against meningococcal disease?

Meningococcal vaccine Signup and view all the answers

What precautions should be taken for persons with surgical asplenia regarding meningococcal disease?

Vaccination Signup and view all the answers

Which biochemical test is negative for meningitidis?

Lactose fermentation Signup and view all the answers

What type of environment does meningitidis prefer for growth?

Atmosphere with 5% CO2 Signup and view all the answers

What is the characteristic of Streptococcus agalactiae?

Gram-positive cocci in chains Signup and view all the answers

Which group is considered at high risk for meningococcal disease?

Children in daycare settings Signup and view all the answers

What is the role of Vancomycin in the Modified Thayer Martin culture?

Inhibits gram-positive bacteria Signup and view all the answers

What type of specimen can be used for laboratory diagnosis in CNS infections?

Blood culture, CSF, nasopharyngeal swab, puncture material Signup and view all the answers

Which microbial agent is associated with a case presenting headache and nuchal rigidity?

Neisseria meningitidis Signup and view all the answers

What type of colony characteristics would you expect from Modified Thayer Martin cultures?

Convex, glistening, elevated, mucoid colonies Signup and view all the answers

What function do antibiotics like Colistin serve in the Modified Thayer Martin culture?

Inhibit gram-negative bacteria Signup and view all the answers

What is the significance of using a Gaspak jar in culture?

Ensures anaerobic conditions Signup and view all the answers

What does a positive Gram stain indicate?

Presence of gram-positive bacteria Signup and view all the answers

What is the function of Nystatin in the Modified Thayer Martin culture?

Inhibits fungal structures Signup and view all the answers

What is the approximate diameter of colonies grown on Modified Thayer Martin culture?

1-5 mm Signup and view all the answers

What does the upregulation of perivascular coagulation indicate in the pathogenesis of DIC?

Increased coagulation activity Signup and view all the answers

Study Notes

Haemophilus influenzae

Haemophilus influenzae is a gram-negative, non-motile, encapsulated, coccobacillary bacterium.
It is a facultative anaerobe and capnophilic.
Requires X (haemin) and V (NAD) factors for growth.
Serotype B is the most invasive type (Hib) and it's capsule is made of polyribitol phosphate.
Polysaccharide capsule has 6 serotypes: a, b, c, d, e, f.
Hib vaccine acts against serotype B.

Neisseria Meningitidis

Neisseria meningitidis is a gram-negative, non-motile, encapsulated, diplococcus. It is oxidase positive.
It is a facultative anaerobe and grows best at 5-10% CO2.
Requires X and V factors for growth.
Clinical specimens for diagnosis: blood culture, CSF, nasopharyngeal swab, puncture material from hemorrhagic lesions.
Modified Thayer-Martin is a selective medium for the cultivation of Neisseria meningitidis. It contains antibiotics like vancomycin, colistin, and nystatin to inhibit contaminants.
It ferments glucose and maltose only.

Meningococcal Meningitis

Meningococcal meningitis can progress to coma within hours of sudden onset of severe headache, vomiting, and stiff neck.
It is the most important complication of meningococcal infections, resulting in acutely inflamed meninges.
It can be associated with altered mental status, confusion, drowsiness, or lethargy.

Meningococcal Septicemia

Early symptoms are nonspecific and suggest a viral illness.
Fulminant cases lead to death within hours of the initial symptoms.
Endothelial injury is central to features of meningococcal septicemia. This injury leads to increased vascular permeability, hypovolemia, tissue edema, proteinuria, and increased perivascular coagulation.

Fulminant Meningococcemia

It can lead to shock, disseminated intravascular coagulation (DIC), and Waterhouse-Friderichsen syndrome.
DIC is a severe bleeding tendency with concurrent severe thrombosis.
Waterhouse-Friderichsen syndrome is a bilateral adrenal hemorrhage that can progress to adrenal necrosis.

Management and Treatment of Meningococcal Infections

Penicillin G is the drug of choice for treating meningococcal infections.
Chloramphenicol or 3rd generation cephalosporins (cefotaxime and ceftriaxone) are options for those with penicillin allergies.
If intracranial pressure (ICP) is increased, medical decompression should be performed first (lumbar tap) to prevent brain herniation.
Therapeutic lumbar tap should be performed daily to relieve cerebral spinal fluid (CSF) pressure.
Post-exposure prophylaxis for close contacts is recommended with ceftriaxone.
For carriers, Rifampicin or ciprofloxacin can be used for eradication.

Meningococcal Vaccine

The vaccine covers serogroups A, C, Y, and W-135.
It is recommended for individuals 9 months to 55 years old.
The recommended schedule is 0, 1-2, and 6 months.
The vaccine is especially recommended for high-risk groups including those with functional or surgical asplenia, C’ deficiency travelers to highly endemic areas, “closed populations” (dormitories, military, childcare), and clinical laboratory workers.

Listeria monocytogenes

Listeria monocytogenes is a gram-positive, facultative anaerobic, motile bacterium.
It is a common cause of meningitis among newborns.
It is a foodborne pathogen.
Immunocompromised individuals are at risk of developing listeriosis which can lead to meningoencephalitis and bacteremia.
It can cross the placenta and cause infections in the fetus, leading to premature birth, spontaneous abortions, or stillbirth.
It produces small zone of hemolysis on blood agar plates.
13 known serovars based on O (somatic) and H (flagellar antigens)
Internalins A and B facilitate phagocytosis by interacting with E-cadherin receptor.
Listeriolysin O (LLO) is a specific beta-hemolysin that mediates rupture of the phagosomal membrane.
PLC A and PLC B allow escape of bacterium into the cytoplasm along with listeriolysin O.
ActA mediates the nucleation of host actin.
Listeria monocytogenes can invade the brain parenchyma, creating cerebritis or focal abscess.

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Description

Test your knowledge on Haemophilus influenzae and Neisseria meningitidis, two significant bacteria in medical microbiology. Understand their characteristics, growth requirements, and clinical significance, including details on their respective vaccines and cultivation methods.