Infectious Diseases Overview
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Questions and Answers

Which bacterial infection is commonly associated with chronic infection of the lung?

  • Brucellosis
  • Typhoid fever
  • Lung abscess
  • Mycobacterium tuberculosis (correct)

    • Which laboratory test is particularly indicated for suspected cases of tuberculosis?

  • ESR > 100 (correct)
  • Anti-Ds-DNA
  • Widal test
  • CBC

    • What type of malignancy is categorized as hematologic?

  • Hypernephroma
  • Leukemia (correct)
  • Hepatoma
  • Lung carcinoma

    • Which therapeutic agent is specifically used for the treatment of amoeba infections?

    <p>Metronidazole (A)</p> Signup and view all the answers

    What imaging study is appropriate for evaluating potential lung infections?

    <p>Chest X-ray (C)</p> Signup and view all the answers

    What is the main causative organism of brucellosis?

    <p>Brucella (D)</p> Signup and view all the answers

    Which of the following is a common mode of infection for HIV?

    <p>Parenteral (C)</p> Signup and view all the answers

    What clinical symptom is indicative of brucellosis?

    <p>Relapsing fever (C)</p> Signup and view all the answers

    Which diagnostic test is best for confirming HIV infection?

    <p>HIV-RNA by PCR (B)</p> Signup and view all the answers

    Which treatment is commonly prescribed for brucellosis?

    <p>Rifampin (B)</p> Signup and view all the answers

    What is a significant complication associated with AIDS?

    <p>Opportunistic infections (A)</p> Signup and view all the answers

    A patient with brucellosis may present with which of the following symptoms?

    <p>Hepatosplenomegaly (A)</p> Signup and view all the answers

    What defines a fever of unknown origin (FUO)?

    <p>Persistent fever for over 38.5 °C for three weeks with no diagnosis (C)</p> Signup and view all the answers

    Which of the following correctly describes the causative organism of typhoid fever?

    <p>Salmonella typhi &amp; paratyphi A &amp; B (D)</p> Signup and view all the answers

    What is the mode of transmission for typhoid fever?

    <p>Feco-oral transmission (B)</p> Signup and view all the answers

    In which week of typhoid fever is the Widal test expected to be positive?

    <p>2nd week (A)</p> Signup and view all the answers

    What clinical manifestation is associated with the 1st week of typhoid fever?

    <p>Headache and relative bradycardia (D)</p> Signup and view all the answers

    Which type of fever is characterized by daily fluctuations of less than 1ºC?

    <p>Sustained fever (A)</p> Signup and view all the answers

    Which of the following regarding the complications of typhoid fever is correct?

    <p>Meningitis is a potential complication (C)</p> Signup and view all the answers

    What is indicated by a culture being positive in the first week of typhoid fever?

    <p>Presence of salmonella bacteria (A)</p> Signup and view all the answers

    How is hyperpyrexia defined in terms of body temperature?

    <p>Body temperature over 40ºC (D)</p> Signup and view all the answers

    Flashcards

    Bacterial Infection

    Infections caused by bacteria, divided into Gram-positive (e.g., streptococci, staphylococci) and Gram-negative (e.g., Klebsiella, Pseudomonas) types.

    Fever (Pyrexia)

    An elevated body temperature above the normal range (36.5–37.2°C).

    Typhoid Fever

    An infectious disease caused by Salmonella bacteria, transmitted through food contaminated with feces (fecal-oral route).

    Salmonella Typhi

    The bacteria that causes typhoid fever

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    Fever Stages

    Different patterns of fever including sustained, remittent, hectic and relapsing.

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    Typhoid Fever Symptoms (1st week)

    Initial phase characterized by step-ladder fever, headache, slow heartbeat (bradycardia), constipation, and a distinctive rash (rose spots).

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    Typhoid Fever Symptoms (2nd week)

    Continued fever, faster heartbeat (tachycardia), diarrhea, and enlarged spleen (splenomegaly) occur. The rash disappears.

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    Typhoid Fever diagnosis

    Diagnosis involves observing symptoms and conducting blood tests (CBC, Widal test) and cultures (blood, stool, urine).

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    Brucellosis (Malta fever)

    An infectious disease caused by the Brucella bacteria, often transmitted through contaminated animal products.

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    Brucellosis Diagnostic Test

    Brucella agglutination test is the best diagnostic test for Brucellosis.

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    AIDS (Acquired Immunodeficiency Syndrome)

    A disease caused by HIV, weakening the immune system through T-lymphocyte infection.

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    AIDS Diagnostic Test

    HIV-RNA by PCR is the optimal diagnostic test for AIDS.

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    Fever of Unknown Origin (FUO)

    A persistent fever (above 38.5°C for 3+ weeks) with no specific cause found after a week of investigation.

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    HIV Infection Modes

    HIV transmission commonly occurs through parenteral, sexual, and vertical contact.

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    Opportunistic Infections

    Illnesses that take advantage of a weakened immune system, common in advanced stages of HIV infections, or other immunodeficiencies.

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    Brucellosis Symptoms

    Brucellosis often presents with bone and muscle pain, vomiting, constipation, and a characteristic relapsing fever pattern.

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    Tuberculosis (TB) causes

    Infections like TB are caused by a bacterium called Mycobacterium tuberculosis and can cause chronic lung infections, often with symptoms like night sweats, weight loss, and a cough with thick sputum.

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    TB investigation

    Diagnosing TB involves lab tests like examining sputum, blood tests (ESR,CBC), and imaging (X-ray) to identify the presence and location of TB in the body.

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    TB treatment

    TB treatment uses a combination of antibiotics, often including isoniazid (INH) and rifampicin, for an extended period to effectively eliminate the bacteria and prevent further damage to the body.

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    Chronic lung infection causes

    Chronic lung infections can arise from various factors, including bacterial (e.g., TB), viral (e.g., EBV, CMV), and even protozoan infections. Immunodeficiencies can also contribute to serious infections.

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    Inflammatory bowel disease (IBD)

    Inflammatory bowel disease is a category of diseases that cause inflammation and damage to the digestive tract.

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    Study Notes

    Infectious Diseases

    • Infectious diseases are a broad category encompassing various illnesses caused by pathogens.
    • Important infectious diseases include typhoid fever, brucellosis, and acquired immunodeficiency syndrome (AIDS).
    • Normal body temperature ranges from 36.5°C to 37.2°C.
    • Fever is defined as having a body temperature above the normal upper limit.
    • Hyperpyrexia is a fever exceeding 40°C.
    • Types of fever include sustained, remittent, hectic, and relapsing fever.

    Aetiological Classification

    • Bacterial:
      • Gram-positive: streptococci, staphylococci
      • Gram-negative: Klebsiella, Pseudomonas, Haemophilus influenza
      • Anaerobic bacteria: bacteroides
    • Mycobacterial: Tuberculosis (TB), Leprosy
    • Spirochetal: Syphilis, Leptospirosis
    • Rickettsia: Typhus
    • Chlamydia
    • Viral: Dengue, Influenza, Herpes simplex virus (HSV), Varicella-zoster virus (VZV), Cytomegalovirus (CMV), Epstein-Barr virus (EBV), Measles, Mumps, Rubella
    • Protozoal: Malaria, Amebiasis, Bilharziasis, Giardiasis
    • Fungal: Candida albicans, Aspergillus niger

    Typhoid Fever

    • Etiology: Salmonella typhi and paratyphi A and B
    • Mode of Infection: Feco-oral transmission
    • Clinical Manifestations:
      • First week: Fever (stepladder pattern), headache, relative bradycardia, constipation, rose spots
      • Second week: Continuous fever, tachycardia, diarrhea, splenomegaly
      • Third week: convalescence begins
    • Complications: Intestinal bleeding, peritonitis, meningitis, encephalitis, convulsions, pyelonephritis
    • Investigations: CBC (leucopenia with relative lymphocytosis), Widal test (positive from the second week – prognostic rather than diagnostic), cultures (blood, stool, urine, in weeks 1-3 respectively).
    • Treatment: Ciprofloxacin, Co-trimoxazole, ceftriaxone

    Brucellosis

    • Etiology: Brucella (melitensis, abortus, or suis)
    • Mode of Infection: Contaminated milk, or remnants from aborted animals.
    • Clinical Picture: Bone and muscle pain, vomiting, constipation, relapsing fever. Fever for 10 days followed by 10 days of apyrexia- cycling fever. Hepatosplenomegaly and lymph node enlargement.
    • Complications: Relapse, infective endocarditis, orchitis, paraplegia (transverse myelitis), abortion.
    • Investigations: CBC (lymphocytosis positive during fever spike), Blood culture, Serological tests (Brucella agglutination test - the best diagnostic test).
    • Treatment: Doxycycline or rifampicin for 6 weeks.

    Acquired Immunodeficiency Syndrome (AIDS)

    • Etiology: Human Immunodeficiency Virus (HIV)
    • Modes of Infection: Parenteral, sexual, vertical
    • Pathogenesis: HIV infects T-lymphocytes, suppressing cellular and humoral immunity. A fall below 200 T-cells/dL leads to opportunistic illnesses and malignancies.
    • Clinical Picture: Asymptomatic phase (up to 10 years), acute HIV syndrome (fever, rigors, arthralgia, rash), symptomatic syndromes (generalized LN enlargement, Constitutional symptoms, Neurological disease, Opportunistic infections, Secondary neoplasms).
    • Investigations: HIV antibodies (screening, appear within 2 weeks of infection), HIV-RNA by PCR (best diagnostic test).
    • Treatment: Anti-retroviral (HAART), Zidovudine 600 mg/day orally (note that HAART involves multiple drugs in practice).

    Fever of Unknown Origin (FUO)

    • Definition: Persistent elevation of body temperature above 38.5°C for 3 weeks without a diagnosed cause. Requires 1 week of inpatient investigations.
    • Causes: Bacterial (TB, infective endocarditis, typhoid fever, brucellosis, lung abscess, pyelonephritis), Viral (EBV, CMV, HIV, hepatitis), Protozoal (malaria, amebiasis), Malignancy (hematologic and non-hematologic), Collagen diseases (rheumatic fever, PAN, SLE), Others (inflammatory bowel disease, hemolysis, cerebral hemorrhage).
    • Undiagnosed Often the cause is unidentified even after comprehensive investigation.

    Other Topics/Notes

    • Preventive measures (hand hygiene, respiratory precautions)
    • Investigations (laboratory, imaging, endoscopy, biopsies, etc.)
    • Treatment regimens (for TB, malaria, etc.). Details on the use of different medicines are not included in this summary for safety and efficacy reasons.

    Pulmonary Tuberculosis (TB)

    • Definition: Chronic lung infection caused by Mycobacterium tuberculosis.
    • Etiology: Mycobacterium tuberculosis (acid-fast, intracellular, aerobic, non-motile bacillus)
    • Risk Factors: Children under 5, close contacts with active TB patients, immunocompromised individuals (AIDS, diabetes, leukemia, steroid users)
    • Mode of Transmission: Droplet infection.
    • Clinical Picture: Symptoms (night fever, sweating, weight loss, appetite loss), cough and expectoration (thick mucoid), hemoptysis (blood-tinged sputum), sings (inspection, percussion, auscultation), complicated TB with massive systemic spread in immunocompromised patients, tubercles in CNS, lungs, pericarditis, Pott's disease of spine, generalized lymphoma.
    • Investigations: Chest X-ray, ESR and CRP (elevated), sputum examination (acid-fast bacilli staining), PCR (Mycobacterial DNA detection), Seriological tests (Quantiferon Gold, ADA), Tuberculin skin testing.
    • Treatment: First-line drugs (isoniazid, rifampicin, pyrazinamide, ethambutol, and streptomycin), combination therapy for long periods, standardized 6-month regimen. Indications for corticosteroids vary.

    Dengue Fever

    • Definition: Viral disease caused by the dengue virus.
    • Etiology: Dengue virus (RNA virus, Flavivirus, arbovirus).
    • Vector: Aedes aegypti mosquito.
    • Pathogenesis: Virus inoculated by the bite of an infected mosquito, replicates in the reticuloendothelial system. Secondary infections may cause antibody response and complications.
    • Clinical Features: Incubation (5-9 days), social history (residence in or travel to endemic region). Initial fever (2-4 days), rapid defervescence, afebrile period (1 day), second fever period (2-3 days). Generalised lymphadenopathy, skin rash (itchy maculopapular), GIT issues, CNS and CVS symptoms,
    • Complications: Dengue shock syndrome (DSS), Dengue haemorrhagic fever (DHF).
    • Investigations: Haematology (Elevated Hct, leucopenia, low platelets), Biochemistry (Elevated liver enzymes), Immunology (Dengue Antibody - IgM and IgG ELISA), Microrbiology (PCR possible).
    • Management: Support (intravenous fluids, colloids, paracetamol). Possible platelet transfusion.
    • Prevention: Vector control, biological agents
    • Prognosis: Mortality 10-30% in dengue haemorrhagic fever.

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    Infectious Diseases PDF

    Description

    Explore the fundamentals of infectious diseases, including their types, causes, and categorization by pathogens. This quiz covers bacterial, viral, and protozoan diseases, alongside key concepts like fever classifications. Test your knowledge on crucial infectious diseases such as AIDS and tuberculosis.

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