Microbiology of Spiroplasma and Lactic Acid Bacteria
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Questions and Answers

What is the principle method used for detection of Spiroplasma?

  • Culture techniques
  • Molecular techniques such as PCR (correct)
  • Gram staining
  • Biochemical tests

    • What is the recommended treatment for Spiroplasma infections in the UK?

  • Doxycycline and azithromycin (correct)
  • Erythromycin and tetracycline
  • Moxifloxacin and streptomycin
  • Ciprofloxacin and amoxicillin

    • What type of bacteria is Spiroplasma?

  • Mollicutes (correct)
  • Firmicutes
  • Actinobacteria
  • Gram negative bacteria

    • What is a characteristic of Lactic Acid Bacteria?

    <p>They are non-motile and produce ATP by substrate level phosphorylation (D)</p> Signup and view all the answers

    What is the byproduct of fermentation in Lactic Acid Bacteria?

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

    What is a unique feature of Lactic Acid Bacteria?

    <p>They are tolerant of acid and have a high GC content (A)</p> Signup and view all the answers

    What is a requirement for the growth of Lactic Acid Bacteria?

    <p>Rich media with yeast and peptone (D)</p> Signup and view all the answers

    What is a characteristic of Spiroplasma citrii?

    <p>It is a high GC gram positive bacteria (A)</p> Signup and view all the answers

    What is the characteristic of Streptococcus cells in terms of division?

    <p>They can divide only in one plain (B)</p> Signup and view all the answers

    What is the primary source of catalase for Streptococcus growth?

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

    Which of the following is NOT a characteristic of Streptococcus?

    <p>Can form spores (D)</p> Signup and view all the answers

    What is the basis of Lancefield grouping of Streptococci?

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

    Which group of Streptococci is associated with the intestinal tract of humans and animals?

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

    What is the result of β-hemolysis on blood agar?

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

    What is the name of the scientist who developed the Lancefield grouping system?

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

    Which of the following is a type of LAB that is commonly used as a probiotic?

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

    What is the percentage of healthy people who may be carriers of group A, beta hemolytic Streps in their throat and nasopharynx?

    <p>5-30% (B)</p> Signup and view all the answers

    What is the name of the toxin encoded by a phage that causes scarlet fever?

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

    What is the name of the disease that occurs in a small percentage of individuals, 2-3 weeks after an untreated pharyngeal infection caused by a β hemolytic group A Strep?

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

    What is the name of the test used to identify group A strep?

    <p>Bacitracin sensitivity test (B)</p> Signup and view all the answers

    What is the name of the phage that encodes the superantigen toxin?

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

    How many antigenically distinct toxins are there in group A strep?

    <p>3 (A)</p> Signup and view all the answers

    What is the name of the disease that is characterized by small vesicles on the skin forming a thin amber crust?

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

    What is the name of the heart condition that can occur as a result of rheumatic fever?

    <p>Rheumatic heart disease (D)</p> Signup and view all the answers

    What is the primary mechanism behind glomerulonephritis following a group A Strep infection?

    <p>An immunological reaction of Strep-directed antibody with the glomerular basement membrane (B)</p> Signup and view all the answers

    What is the primary reservoir for Group B Streptococci?

    <p>Vaginal flora of women (B)</p> Signup and view all the answers

    What is a significant complication of untreated Group B Streptococcal infections in newborns?

    <p>Meningitis with high fatality rates (D)</p> Signup and view all the answers

    What is the name of the test used to identify Streptococci?

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

    What is the primary concern associated with Group D Streptococci?

    <p>Increasing resistance to vancomycin (B)</p> Signup and view all the answers

    What is the characteristic of Viridans Streptococci that makes them significant causes of bacterial endocarditis?

    <p>Their ability to inhabit the throat and nasopharynx of humans (C)</p> Signup and view all the answers

    What is the name of the Streptococcal species that causes dental caries?

    <p>S. mutans (C)</p> Signup and view all the answers

    What is the characteristic of non-suppurative diseases caused by Group A Streptococcal infections?

    <p>Immunological reaction leading to tissue damage (C)</p> Signup and view all the answers

    What is the characteristic shape of Streptococcus pneumoniae?

    <p>Lancet-shaped (A)</p> Signup and view all the answers

    What is the function of the capsule in Streptococcus pneumoniae?

    <p>To resist phagocytosis (A)</p> Signup and view all the answers

    How many types of Streptococcus pneumoniae are there based on the antigenicity of the capsular polysaccharide?

    <p>90 (A)</p> Signup and view all the answers

    What is the percentage of Streptococcus pneumoniae infections that lead to bacteremia?

    <p>25% (B)</p> Signup and view all the answers

    What is the typical morphology of Streptococcus pneumoniae colonies on blood agar?

    <p>Doughnut-shaped and sunken in center (D)</p> Signup and view all the answers

    What is the principle of the quellung test?

    <p>Capsular swelling due to antibody attachment (B)</p> Signup and view all the answers

    What is the typical treatment for Streptococcus pneumoniae meningitis?

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

    What is the approximate annual mortality rate due to Streptococcus pneumoniae infections?

    <p>1,000,000 (D)</p> Signup and view all the answers

    Streptococcus divides in multiple planes.

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

    Lactic acid bacteria are grouped based on their morphology.

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

    Homofermentative lactic acid bacteria produce lactic acid and CO2 as byproducts.

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

    Leuconostoc is a heterofermentative lactic acid bacterium.

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

    Lactobacillus bulgaricus is used in the production of Swiss cheese.

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

    Streptococcus thermophilus is used in the production of sour cream and ripe cream.

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

    Lactic acid bacteria are used in the production of starter cultures.

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

    Pediococcus forms spheres in chains.

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

    Mycoplasma genitalium has a genome size of 816 kbp.

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

    Mycoplasma pneumoniae is a strict anaerobe.

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

    The human genome contains approximately 5440 kbp of DNA.

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

    Ureaplasma is a type of Mycoplasma that requires cholesterol and urea for growth.

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

    Acholeplasma is a type of Mycoplasma that is a strict anaerobe.

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

    Spiroplasma is a type of Mycoplasma that causes disease in humans.

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

    Mycoplasma pneumoniae is typically transmitted through contaminated food and water.

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

    Primary atypical pneumonia caused by Mycoplasma pneumoniae is typically seen in individuals over 50 years old.

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

    M.pneumoniae can be grown in media containing serum without penicillin.

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

    The bacterium Mycoplasma pneumoniae produces oxygen peroxide.

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

    Ureaplasma urealyticum is a type of genital Mycoplasma that causes pneumonia.

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

    Erythromycin is effective against Legionella infections.

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

    Mycoplasma pneumoniae infections can be diagnosed using serological tests such as PCR.

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

    Mycoplasma genitalium can cause infertility in women.

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

    Mycoplasma pneumoniae is resistant to antibiotics that act on the cell membrane.

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

    M.hominis can cause pneumonia in adults.

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

    Streptococcus lactis is a type of bacteria that requires complex media for growth.

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

    Leuconostoc citrovorum is a type of LAB that is commonly used as a probiotic.

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

    Streptococcus durans is a type of bacteria that can make haem group of cytochromes and catalase.

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

    Lactic Acid Bacteria are able to divide in multiple planes, forming clusters.

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

    Streptococcus is a type of bacteria that requires blood agar as a primary source of catalase.

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

    Enterococcus faecalis is a type of LAB that is commonly used in the production of soft Italian cheeses.

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

    Rebecca Lancefield is the scientist who developed the Lancefield grouping system for Streptococci.

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

    Group D Streptococci are typically found in the intestinal tract of humans and animals.

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

    Streptococcus pyogenes is a type of α-hemolytic bacteria.

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

    The Bacitracin sensitivity test is used to identify Group B Streptococci.

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

    Necrotizing fasciitis is a non-suppurative disease caused by Group A Streptococcal infections.

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

    Rheumatic fever is a result of Strep sore throat caused by a pyrogenic toxin-producing organism.

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

    There are five antigenically distinct toxins in Group A Strep.

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

    Scarlet fever is a result of Strep sore throat caused by a non-pyrogenic toxin-producing organism.

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

    Streptococcal impetigo is a disease that occurs in a small percentage of individuals, 2-3 weeks after an untreated pharyngeal infection.

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

    Rheumatic heart disease is a rare condition in developing countries.

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

    Study Notes

    Spiroplasma

    • Detection relies on molecular techniques (PCR) due to difficulty in culturing
    • Recommended treatment: doxycycline pretreatment then azithromycin (or moxifloxacin)
    • Antibiotic resistance is high

    The Lactic Acid Bacteria

    • Gram-positive bacteria
    • Includes Streptococcus, Lactobacillus, and Enterococcus
    • Produce lactic acid as a product of fermentation
    • Non-spore forming, non-motile, and lack cytochromes
    • Obtain energy by substrate level phosphorylation and not by electron transport and oxidative phosphorylation
    • Normally obtain energy only from sugars
    • Limited biosynthetic capability and require many vitamins, amino acids, purines, and pyrimidines
    • Aerotolerant anaerobes, growth not affected by presence of air
    • Tolerant of acid, and can produce and tolerate high concentrations of lactic acid
    • Found in cultured buttermilk, sour cream, cottage cheese, and cheeses

    Streptococcus

    • Spherical cells divide only in one plane and form chains
    • Require complex media for growth
    • Unable to make haem group of cytochromes or catalase
    • Grown on blood agar (good source of catalase)
    • Grouping of Streptococci:
      • Hemolysis: β (complete hemolysis), α (incomplete hemolysis), and γ (no hemolysis)
      • Antigenically/Serologically (Lancefield Groups): A, B, C, D, etc. based on specific carbohydrate antigen extracted by heating cells up to 150°C
    • Streptococcus pyogenes (Group A Strep):
      • β-hemolytic
      • Causes many streptococcal diseases in humans
      • Antigenicity of M-proteins in the cell wall provides sub-classification into over 100 sub-serotypes
      • Found in 5-30% of healthy people as carriers in their throat and nasopharynx
      • Bacitracin sensitivity test
    • Streptococcal diseases:
      • Strep Throat
      • Impetigo
      • Scarlet Fever: caused by a pyrogenic toxin-producing organism, symptoms include fever, toxic shock, and erythematous rash
      • Cellulitis: infection of the deep layers of the skin
      • Necrotizing fasciitis: highly invasive, toxigenic, infection of soft tissues and fascia
      • Non-suppurative diseases:
        • Rheumatic fever: occurs in a small percentage of individuals, 2-3 weeks after an untreated pharyngeal infection
        • Glomerulonephritis: most cases occur about a week after group A Strep infection, leads to loss of protein through kidneys and hypertension
    • Other Streptococci:
      • Group B Streptococci: S. agalactiae, found in vaginal flora of 25% of women, may cause serious infections in newborns
      • Group D Streptococci: faecal flora, enterococci, cause urinary and wound infections, and are a major problem of vancomycin-resistance
      • α-hemolytic Streptococci: Viridans group, includes many species that are normal inhabitants of throat and nasopharynx of humans
      • Streptococcus pneumoniae:
        • Lancet-shaped organism, usually arranged in pairs
        • Virulent organisms are encapsulated, resist phagocytosis
        • Subdivided into 90 types on the basis of antigenicity of capsular polysaccharide
        • Found in the normal commensal of the upper respiratory tract
        • Causes streptococcal pneumonia, accounts for about one million deaths per annum worldwide, and is the second most common cause of meningitis in adults

    Lactic Acid Bacteria (LAB)

    • LAB are used to eliminate competition in selective media
    • They can be grouped by their fermentation patterns:
      • Homofermentative: produces a single fermentation product (lactic acid) using the Embden-Meyerhof (glycolytic) pathway
      • Heterofermentative: produces lactic acid and other products (CO2 and ethanol) using the pentose phosphate pathway
    • Examples of LAB and their products:
      • Lactobacillus bulgaricus: Bulgarian buttermilk, yoghurt, kefir, koumiss, Swiss, Emmental, and Italian cheeses
      • Lactobacillus acidophilus: acidophilus buttermilk, Emmental, Cheddar, and Italian cheeses
      • Streptococcus thermophilus: acid, yoghurt, and Italian cheeses
      • Streptococcus diacetilactis: acid, sour cream, ripe cream, butter, cheese, buttermilk, and starter cultures

    Mycoplasmas

    • Mycoplasma genitalium has the smallest known genome of any self-replicating organism (580 kbp encoding 472 genes)
    • Mycoplasma pneumoniae has a larger genome (816 kbp containing 679 putative genes)
    • During evolution, mycoplasmas have undergone multiple reductions in genome size and have an unusually high rate of evolution
    • Mollicutes (Mycoplasma-like organisms) are:
      • Mycoplasmas: require cholesterol, parasitic on animal mucous membranes, facultative anaerobes, and over 60 species recognized
      • Ureaplasma (T-Strain Mycoplasmas): microaerophilic, require cholesterol and urea for growth, and may be associated with nongonococcal urethritis
      • Acholeplasma: widely distributed animal parasites, facultative aerobes, able to grow in the absence of sterols
      • Anaeroplasma: strict anaerobes, inhabit bovine or ovine rumen
      • Spiroplasma: helical, motile, parasites on arthropods and plants, but a few cause disease in animals

    Mycoplasma pneumoniae

    • Causes primary atypical pneumonia in humans (PAP or "walking pneumonia")
    • Affects individuals 5-20 years old
    • Symptoms range from mild flu-like disease to severe pneumonia with fever, chills, and malaise
    • Protracted course with gradual resolution (month)
    • Transmitted through close personal contact via respiratory droplets
    • May be a prevalence of infections occurring in autumn
    • The bacterium settles on a respiratory epithelial cell, binds to it, and produces hydrogen peroxide, which is responsible for much of the initial cell disruption in the respiratory tract

    Diagnosis and Treatment of Mycoplasma pneumoniae

    • Diagnosis:
      • Clinical symptoms
      • Serological tests (Serum cold agglutination, Complement fixation test, ELISAs)
      • DNA test (PCR) is replacing serological tests
      • Microbiological detection: not that useful because culture is slow
    • Treatment:
      • Erythromycin, doxycycline (not for children), azithromycin, and levofoxacin
      • Erythromycin is often used as it is also effective against legionella

    GENITAL MYCOPLASMAS

    • Mycoplasma genitalium:
      • Causes non-gonococcal (non-chlamydial) urethritis (NGU)
      • May be associated with infertility in men and women
      • Transmitted by direct venereal contact and vertically transmitted from mother to offspring
    • Mycoplasma hominis and Ureaplasma urealyticum:
      • 50% of normal adults have antibodies
      • Causes of non-gonococcal urethritis (NGU)
      • May be associated with infertility in men and women

    Streptococcus

    • Spherical cells divide only in one plane and form chains
    • Require complex media for growth
    • Unable to make haem group of cytochromes or catalase
    • Grown on blood agar (good source of catalase)

    Grouping of Streptococci

    • Hemolysis:
      • β - complete hemolysis -> clear zone
      • α - incomplete hemolysis of red blood cells -> greenish-brown zone
      • γ - hemolytic - no hemolysis
    • Antigenically/Serologically:
      • Lancefield Groups of β-hemolytic Streps (A, B, C, D…H and K-W)
      • Group A - S. pyogenes
      • Group B - Cattle and humans (e.g. S. agalactiae)
      • Group D - Intestinal tract of man and animals (Enterococcus)

    Group A Strep

    • β hemolytic
    • Causes many of the streptococcal diseases of humans
    • Antigenicity of M-proteins in the cell wall provides sub-classification of group A into over 100 sub-serotypes
    • Habitat: 5-30% of healthy people may be carriers of group A, beta hemolytic Streps in their throat and nasopharynx

    Streptococcal Diseases

    • Strep throat
    • Impetigo
    • Scarlet fever
    • Cellulitis
    • Necrotizing fasciitis
    • Non-suppurative diseases:
      • Rheumatic fever
      • Rheumatic heart disease

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