Viridans Group Streptococci Quiz

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Questions and Answers

Which of the following species is NOT part of the Viridans Group Streptococci?

S.pneumoniae (correct)

S.sanguinis

S.gordonii

S.mitis

Which species is included in the Viridans Group Streptococci?

S.agalactiae

S.mutans (correct)

S.aureus

S.pyogenes

What is the primary characteristic of Viridans Group Streptococci?

They are resistant to antibiotics.

They are known for causing throat infections.

They belong to the beta-hemolytic group.

They are typically associated with dental caries. (correct)

Which of these is a species belonging to the Viridans Group Streptococci?

S.gordonii Signup and view all the answers

Which species is identified among the Viridans Group Streptococci commonly found in the human mouth?

S.salivarius Signup and view all the answers

Which of the following is NOT a pathogen typically associated with cardiovascular diseases?

Hepatitis B virus Signup and view all the answers

Which pathogen is most commonly linked to infective endocarditis?

Viridans group streptococci Signup and view all the answers

What type of pathogen is associated with the development of rheumatic heart disease?

Bacterial pathogens Signup and view all the answers

Which of these viral infections has been implicated in cardiovascular diseases?

Human Immunodeficiency Virus (HIV) Signup and view all the answers

Which of the following pathogens is known to increase the risk for atherosclerosis?

Chlamydophila pneumoniae Signup and view all the answers

In which bodily fluids is Epstein–Barr virus primarily shed?

Saliva and genital secretions Signup and view all the answers

How long can Epstein–Barr virus be detected in saliva and genital secretions?

Weeks or months Signup and view all the answers

What is one characteristic of the infectious period of Epstein–Barr virus?

Can span several weeks or months Signup and view all the answers

Which of the following pathogens is primarily associated with the shedding in saliva?

Epstein–Barr virus Signup and view all the answers

Which pathogen is NOT commonly shed in saliva?

Streptococcus pneumoniae Signup and view all the answers

What is a potential consequence of an enlarged spleen?

Splenic rupture Signup and view all the answers

What precaution should patients with an enlarged spleen take?

Refrain from contact sports Signup and view all the answers

What is a common recommendation for managing symptoms related to splenomegaly?

Rest and avoid physical exertion Signup and view all the answers

Which of the following is NOT a complication associated with an enlarged spleen?

Increased appetite Signup and view all the answers

What is one possible complication that may arise from splenic rupture?

Reduced blood pressure Signup and view all the answers

What is the primary reservoir for T.gambiense?

Humans Signup and view all the answers

Which of the following animals is NOT a reservoir for T.rhodesiense?

Pigs Signup and view all the answers

In which type of animal can T.rhodesiense be found as a reservoir?

Both domestic and wild animals Signup and view all the answers

What differentiates the reservoirs of T.gambiense and T.rhodesiense?

T.gambiense has a human reservoir only, while T.rhodesiense has animal reservoirs. Signup and view all the answers

Which domestic animal is mentioned as a reservoir for T.rhodesiense?

Sheep Signup and view all the answers

What is revealed by Giemsa-stained slides of blood and lymph node aspirations from infected patients?

Typical trypomastigote morphologic forms Signup and view all the answers

What type of samples are primarily discussed in the context of trypomastigote identification?

Blood and lymph node aspirations Signup and view all the answers

Which staining method is used to identify typical morphologic forms of trypomastigotes?

Giemsa stain Signup and view all the answers

Which morphologic form is specifically associated with infections seen in stained slides from patients?

Trypomastigote Signup and view all the answers

What type of patient samples would NOT typically be used for identifying trypomastigote forms?

Skin scrapings Signup and view all the answers

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Study Notes

Cardiovascular Block Infections: Pathogens Causing Diseases

Objectives: Students should understand pathogens causing cardiovascular diseases, the properties, transmission, clinical findings, and laboratory diagnosis of Viridians Group Streptococcus (VGS), Epstein bar virus, and Trypanosoma and other pathogens causing CVS disease.

Viridans Group Streptococcus (VGS)

Lancefield Classification: Based on carbohydrate; non-groupable.
Species: S. sanguinis, S. mutans, S. mitis, S. gordonii, S. salivarius, S. anginosus, S. milleri, and S. intermedius
Alpha-hemolytic: Produce hydrogen peroxide, changing hemoglobin (red) to biliverdin (green), surrounding colonies.
Gram-positive cocci: Spherical, arranged in chains or pairs.
Catalase-negative
Normal Oropharyngeal Flora: Present in the mouth.

VGS Pathogenesis

Uncertain: No exotoxins or tissue-destructive enzymes have been identified

VGS Pathogenesis II

Virulence Factor (S. pneumoniae): Antiphagocytic polysaccharide capsule.
Virulence Factor (VGS): Produce glycocalyx which allows adherence to heart valves causing endocarditis.
Common cause of Infective Endocarditis.
Transmission: Enters bloodstream from oropharynx typically after dental surgery.
High Mortality: 100% fatal without effective antimicrobial treatment.

Signs of Endocarditis

Fever, heart murmur, anemia, embolic events: Splinter hemorrhages, subconjunctival petechial hemorrhages, and Janeway lesions.
Caused by Vegetations: On the Heart Valve

VGS, S. milleri, S. anginosus, and S. intermedius

Brain Abscesses: Often in combination with mouth anaerobes; a mixed aerobic-anaerobic infection.
Predisposing Factor: Dental surgery provides a portal to the bloodstream.

Laboratory Diagnosis of VGS

Alpha-hemolytic colonies: on blood agar. Differentiation from S. pneumoniae (also alpha-hemolytic).
Resistance to Bile and Optochin: VGS readily grow in the presence of these substances, pneumococci do not.
Biochemicals tests: Used for species classification

Treatment of VGS Endocarditis

Prolonged Penicillin Treatment: For endocarditis caused by VGS.
Enterococci Resistance Treatment: Requires Penicillin or Vancomycin combined with an Aminoglycoside.

Treatment of VRE

Linezolid (Zyvox) and Daptomycin (Cubicin) : Used to treat infections caused by Vancomycin-Resistant Enterococci (VRE).

Epstein-Barr Virus (EBV)

Family: Herpesviridae, second largest to Poxviruses.
Virus Type: Enveloped, double-stranded DNA, icosahedral.
Envelope Origin: From nuclear membrane.
Morphology: Identical among all herpesviruses, not distinguishable by electron microscopy.

Epidemiology of EBV Infection

Transmission: Through saliva and sexual contact (kissing disease).
High Prevalence: Infections with EBV are common in children and sexually active adolescents, infecting 95% in the UK before the age of 25.
Incubation Period: 2-3 weeks.
Infectious Period:
Shedding in saliva and genital secretions for weeks or months.

Reactivation and Risk Groups EBV

Reactivation: Latent infections can frequently reactivate in immunosuppressed individuals.
At-risk groups: Immunosuppressed people.

Symptoms of EBV Infections

Asymptomatic: Infection can be asymptomatic in many people.
Mononucleosis/Glandular Fever: Commonly associated symptoms are sore throat, hepatitis, lymphadenopathy, fever and malaise.

Hepatic Splenomegaly (EBV Complications)

Hepatosplenomegaly: Occurs in approximately 5-10% of cases.
Splenomegaly (high frequency): Occurs in 50 to 70% of cases.
Liver function tests: (LVF): Typically mildly elevated
Alanine Aminotransferase (ALT) or Serum Glutamic-Pyruvic Transaminase (SGPT).

Laboratory Diagnosis of EBV

EBV IgM: Positive result indicates recent infection. Interpretation requires careful examination, and factors like rheumatoid factor interference.
EBV virus capsid antigen (VCA): Indicates previous or current EBV infection.
EBV Nuclear Antigen (EBNA): Positive result indicates EBV infection more than 3 months prior.
Antibody Test (EBNA and VCA ): False negative results due to age and immunosuppression are possible.
Paul Bunnel/Mono spot test: Provides quick diagnosis but is prone to false positives and negatives; not useful in individuals younger than 16.
EBV DNA assays: Detects EBV DNA through Quantitative PCR; guides severity in immune-compromised patients.

Complications of EBV Infections

Rare: Most cases are self-limiting diseases, but complications can occur.
Chronic fatigue syndrome: Some patients may experience weeks to months of tiredness and fatigue post-acute EBV.
Lymphadenopathy: Can accompany or not accompany chronic fatigue syndrome.
Splenic Rupture: Rarely, an enlarged spleen may cause splenic rupture, so people avoid contact sports until acute symptoms subside.
Guillain-Barré Syndrome: A rare post-infectious complication presenting as ascending motor paralysis due to immune-mediated demyelination of the spinal cord.
Associated Malignancies: Burkitt's lymphoma, Nasopharyngeal carcinoma, Lymphoproliferative disease (LPD)/lymphoma (more prevalent in immunosuppressed patients).
X-linked Lymphoproliferative Syndrome: Due to X-chromosome-linked recessive genetic defect; leads to an impaired response to EBV, resulting in either death from excessive EBV infection or lymphoproliferative malignancies.

EBV Differential Diagnosis and Treatment

Differential Diagnosis: Cytomegalovirus, Toxoplasma gondii, Adenovirus
Treatment: No effective antiviral drugs are available for EBV infections.
Reduction of symptoms in immunosuppressed patients: Reducing immunosuppressive medication may reduce disease severity and frequency of reactivation.

Infection Control EBV

Avoid Transmission: Sharing drinking vessels and bottles should be avoided to stop transmission via saliva.

Trypanosomes

Medically Important Genera: Leishmania and Trypanosoma
Characterization: Flagellated protozoa in peripheral blood circulation. Infect blood and tissue.
Life Cycle: Invertebrates (vertebrate host and insect vector).

African Trypanosomiasis (Sleeping Sickness)

Causes (Genus Trypanosoma): T. brucei gambiense and T. brucei rhodesiense.
Causes: Slow-onset chronic in T. brucei gambiense cases. Causes fast-onset acute in T. brucei rhodesiense cases.
Prevalence: T. brucei gambiense: Central and Western Africa. T. brucei rhodesiense: East African (Rhodesian).
Reservoirs: T. brucei gambiense: Humans. T. brucei rhodesiense: Domestic animals and wild animals (e.g., antelopes).

Important Properties of Trypanosoma

Morphology & Life Cycle Similarity: Both gambiense and rhodesiense species are similar.
Vector: Tsetse Fly.
Reservoir: Humans are a reservoir for T. b. gambiense but not for T. b. rhodesiense.
Life Cycle:
begins with ingestion of blood trypomastigotes → multiplication in the insect gut
transform to procyclic trypomastigotes
migrate to salivary glands →transform into Epimastigotes
multiply further in salivary glands →Metacyclic trypomastigotes
Infected saliva injected into skin → bloodstream → blood-form trypomastigotes
Multiple and complete cycle →replication and cycle repeats

Antigenic Variations of Trypanosoma

Remarkable: Hundreds of antigenic types found.
Mechanism of variation: Caused by movement of glycoprotein genes to preferential locations on the chromosome; the gene for the modified glycoprotein is transcribed to mRNA.
Result: Evasion of host immune response.

Pathogenesis and Epidemiology of Trypanosoma

Spread to Lymph Nodes and Brain: Trypomastigotes spread from skin → lymph nodes → brain.
Demylating Encephalitis: The typical somnolence-sleeping sickness-progresses to a coma as the disease advances; results from demyelinating encephalitis.
Cyclical Fever: Approximately every two weeks; related to antigenic variation.

Epidemiology of Trypanosoma

Endemic in Sub-Saharan Africa: The specific area where the insect vector lives.
Blood transfusion, Organ Transplant, Congenital Transmission: T. b. gambiense also spreads via blood transfusion, organ transplantation, or congenital transmission.
Fly's infectious period: Infective throughout their life span (2-3 months).

Clinical Findings of Trypanosoma

Sleep Sickness symptoms: The symptoms associated with sleeping sickness are the typical pattern of this disease progress.
Low-Grade vs More Acute Progressive: Gambiense: Low-grade chronic that develops in a few years; Rhodesiense: More Acute and rapidly progressive if untreated.
Lesions, Fever, Lymphadenopathy: Initial lesion at the site of the fly’s bite becomes an indurated skin ulcer or chancre; intermittent fever & lymphadenopathy develops after the organism enters the blood.
Posterior Cervical Lymph Nodes: Enlargement of the lymph nodes located on the posterior cervical area is a characteristic sign, which is called Winterbottom’s sign.
Encephalitis: Initial symptoms are characterized by headache, insomnia, mood swings, muscle tremors, slurred speech, apathy and that progresses to somnolence and coma.
Pneumonia and death: Untreated disease is commonly lethal due to pneumonia.

Laboratory Diagnosis of Trypanosoma

Microscopic Examination in Early Stages: Blood smears (thin/thick): Identify trypomastigotes.
Aspirates of Chancre or Lymph Nodes: Identify parasites and aid in diagnosis.
CSF analysis-Late Stage: Shows detection of trypanosomes + high levels of IgM and protein, and confirms a patient in the encephalopathic stage.
Serologic tests (IgM): Aid diagnosis, using ELISA.

Treatment of Trypanosoma

Early Treatment (essential): Initiating treatment before encephalopathy develops is crucial - Suramin (most effective but has difficulty crossing the blood-brain barrier - early treatment is essential)
Alternative Drug: Pentamidine.
CNS symptoms: If central nervous system symptoms are present, suramin (to clear the parasitemia) followed by Melarsoprol is given.

Prevention of Trypanosomiasis

Protection against Fly Bite: Using netting, protective clothing, clearing forests near villages, and using insecticides.

Trypanossma Cruzi (American Trypanosomiasis)

Causative Agent: Trypanosoma cruzi
Common Geographic Area: Southern United States, Mexico, and parts of Central and South America (i.e. the Americas).
Synonyms: Chagas’ disease or American trypanosomiasis
Disease Course: Disease course for this illness often presents with cardiac and gastrointestinal distress.

Transmission of Trypanosoma Cruzi

Reduviid Bug Vector: Transmission occurs when an infected reduviid bug (often called a "kissing bug") defecates trypomastigotes near the bite site.
Itching Sensation: Host scratching the bite area helps transmit trypomastigotes.

American Trypanosoma Life Cycle

Transform into Amastigotes: Following entry into the host, trypomastigotes invade surrounding cells, transforming into amastigotes.
Multiplication and Conversion: Amastigotes multiply, destroying host cells, then converting back to trypomastigotes.
Replication and cycle repeats: The resulting trypomastigotes migrate through the blood, penetrate additional cells, and transform back into amastigotes; the replication cycle repeats.
Defecation following the cycle: Trypomastigotes are passed through the reducing bug’s feces when near the next blood meal site.

Diagnosis of T. cruzi

Giemsa-stained blood slides: Typical trypomastigotes are detected.
Lymph Node Biopsy: Giemsa-stained slides from lymph node biopsies may reveal amastigotes.
Blood Culture: A helpful addition to the diagnostic process.
Serologic Tests: Tests includes CF, DAT, Indirect Immunofluorescence (IIF), and PCR.
ELISA testing: Helpful in blood donor screening to ensure the safety of transfusable blood.

Treatment T. cruzi

Nifurtimox (Lampit): The treatment of choice for T. cruzi infections.
Other medications Benznidazole, allopurinol, and ketoconazole.

Prevention of T. cruzi

Elimination of Reduviid Nests: Eradication and reduction of reduviid nests using pest control (insecticides), preventing further transmission.
Construction of homes without open areas: Prevents the housing of the insects and their nesting.
DDT use: DDT can help control population but is less effective for the T. cruzi.
Educational programs: Designed to inform people about disease, transmission, and possible reservoirs to help combat infections.

Additional Notes

These notes summarize the provided information. Some information, such as names and specific patient details, are excluded.*

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Description

Test your knowledge about the Viridans Group Streptococci and their role in cardiovascular diseases. This quiz covers species identification, characteristics, and their associations with various infections. Challenge yourself and deepen your understanding of these important microorganisms.