Streptococcus 2

• What type of bacteria is Streptococcus pneumoniae?

  Gram positive bacteria
• What is the shape of Streptococcus pneumoniae?

  Lancet-shaped
• How do Streptococcus pneumoniae bacteria arrange themselves?

  They arrange in pairs, known as diplococci
• Are Streptococcus pneumoniae motile or non-motile?

  Non-motile
• What is the catalase reaction of Streptococcus pneumoniae?

  Catalase negative
• Where is Streptococcus pneumoniae commonly found in the human body?

  As a commensal in the nasopharynx
• What is the composition of the capsule of Streptococcus pneumoniae?

  Polysaccharide
• What is the role of the capsule in Streptococcus pneumoniae?

  It is anti-phagocytic and antigenic
• How many serotypes of Streptococcus pneumoniae are there?

  More than 90 serotypes
• Which serotypes of Streptococcus pneumoniae are the most virulent?

  Serotypes 1 to 25
• What is the function of autolysin in Streptococcus pneumoniae?

  It is responsible for the release of intracellular virulence factors
• What does pneumolysin do?

  It attacks pulmonary epithelial and endothelial cells
• What are some predisposing factors for Streptococcus pneumoniae infections?

  Children and elderly, viral infections, chronic diseases, smoking, and diabetes
• What diseases are caused by Streptococcus pneumoniae?

  Lobar pneumonia, meningitis, otitis media, and more
• What is the main cause of lobar pneumonia?

  Pneumococci are the major cause
• How is lobar pneumonia transmitted?

  Through aerosols from person to person
• What is the pathology of lobar pneumonia?

  Consolidation of alveoli filled with protein-rich edema fluid
• What are the clinical features of lobar pneumonia?

  Sudden onset, productive cough, fever, and pleuritic chest pain
• What specimens are used for diagnosing Streptococcus pneumoniae?

  Sputum and CSF
• What does a Gram stain reveal for Streptococcus pneumoniae?

  Gram positive diplococci
• What culture medium is used for Streptococcus pneumoniae?

  Blood agar
• What biochemical reaction is Streptococcus pneumoniae sensitive to?

  Optochin
• What is the Quellung reaction used for?

  To detect capsular swelling with anticapsular antibodies
• What has caused resistance to penicillin in Streptococcus pneumoniae?

  Alteration of penicillin-binding proteins (PBP)
• What are some treatments for Streptococcus pneumoniae infections?

  Vancomycin, linezolid, macrolides, and 3rd generation cephalosporins
• What is the purpose of pneumococcal vaccines?

  To prevent infections caused by Streptococcus pneumoniae
• What is the main characteristic of viridans streptococci?

  They are mouth commensals and low virulent
• Which viridans streptococci are important members?

  Streptococcus mutans, Streptococcus mitis, and Streptococcus milleri group
• What disease is primarily caused by Streptococcus mutans?

  Dental caries
• What is the pathogenesis of sub-acute bacterial endocarditis (SBE) caused by viridans streptococci?

  Transient bacteremia after dental procedures leads to bacteria adhering to damaged heart valves
• What are the clinical features of SBE?

  Low grade fever, anemia, weight loss, and heart murmurs
• What are the major criteria for diagnosing infective endocarditis?

  Positive blood culture and evidence of endocardial involvement
• What is the significance of the bile esculin test for enterococci?

  It tests the ability to convert esculin to esculetin
• What infections are commonly caused by enterococci?

  Urinary tract infections, wounds infections, and endocarditis
• What is the treatment for infections caused by enterococci?

  Resistance to penicillin, cephalosporins, and vancomycin
• What is the role of Streptococcus bovis?

  It causes endocarditis and bacteremia in patients with colon carcinoma
• What are Peptostreptococci?

  Anaerobic gram positive cocci that are normal flora of human mucocutaneous surfaces
• What are the virulent factors of Streptococcus pneumoniae?

  • Capsule: Polysaccharide, anti-phagocytic, antigenic
  • Autolysin: Peptidoglycan hydrolase, releases virulence factors
  • Pneumolysin: Attacks pulmonary cells, affects respiratory cilia
• What are the diseases associated with Streptococcus pneumoniae?

  • Lobar pneumonia
  • Meningitis
  • Otitis media
  • Mastoiditis
  • Sinusitis
  • Endocarditis
  • Bacteremia and septicemia
  • Peritonitis
  • Arthritis
• What are the predisposing factors for infections caused by Streptococcus pneumoniae?

  • Children and elderly
  • Viral infections of respiratory tract
  • Chronic lung, heart, and liver diseases
  • Smoking and alcoholism
  • Diabetes mellitus
  • Nephrotic syndrome
  • Sickle cell disease
  • Splenectomy
  • Leukemias and other hematologic malignancies
  • Primary and secondary immunodeficiencies (HIV/AIDS)