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Questions and Answers
Which of the following statements about Porphyromonas catoniae is true?
What is the primary disease associated with Legionella pneumophila?
Which Prevotella species is known to be associated with periodontal disease?
Which Mycobacterium species is primarily linked to leprosy?
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What is the only member of the genus Leptotrichia?
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What is the primary organism responsible for infections in neonates as indicated by its classification?
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Which species is known to cause enamel demineralization?
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Which of the following organisms is part of the Neisseriaceae family associated with gonorrhea?
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Which group of bacteria is commonly associated with gas gangrene?
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Which organism is classified as a commensal species that can exhibit pathogenic behavior under certain conditions?
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What is the significant pathogenic feature of Streptococcus pyogenes?
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What type of bacteria are typically recognized as obligate anaerobes?
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Which species of Neisseria is associated with meningitis?
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Study Notes
Streptococci
- Streptococcus pyogenes - Group A
- Streptococcus agalactiae - Group B
- Found in the female genital tract and can cause infection in neonates
- Group C strains cause disease in animals
- Enterococci - Group D
- Produces toxins: streptolysin O, streptolysin S, hyaluronidase, streptokinase, erythrogenic toxin
- Pathogenicity: causes pharyngitis (Strep throat), scarlet fever, cellulitis, impetigo, necrotising fasciitis, toxic shock
- Complications: rheumatic fever, acute glomerulonephritis
- Treatment: penicillin
- Streptococcus agalactiae (Group B) causes meningitis, septicaemia, pneumonia in neonates
- Treatment: penicillin
Oral Streptococci
- Include: Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis, Streptococcus salivarius, Streptococcus mitis
- Can cause infective endocarditis (viridans streptococci) if they enter the bloodstream
Staphylococci
- Staphylococcus aureus: commonly found on skin and mucous membranes
- Produces: coagulase, hyaluronidase, lipase, protease, hemolysin, enterotoxins
- Staphylococcus epidermidis: part of the normal skin flora
- Can cause infections if the immune system is compromised
- Pathogenicity: causes boils, abscesses, cellulitis, food poisoning, impetigo, toxic shock syndrome
- Treatment: methicillin, vancomycin, linezolid
Enterococci
- Eg enterococcus faecalis
- Pathogenicity: causes urinary tract infections, endocarditis, wound infections
- Treatment: vancomycin, linezolid
Actinomycetes
- Types: Actinomyces israelii, Actinomyces odontolyticus
- Actinomyces odontolyticus can cause enamel demineralisation
- Actinomyces israelii: part of the normal oral flora
- Pathogenicity: causes actinomycosis, a chronic infection that can affect various tissues
- Characterized by abscesses and draining tracts
- Types: Actinomyces israelii, A. naeslundii, A. viscosus
- Treatment: penicillin, surgical drainage
Clostridia
- Types: Clostridium tetani, Clostridium botulinum, Clostridium perfringens
- Clostridium tetani: causes tetanus
-
Clostridium botulinum: produces botulinum toxin, causing botulism
- Pathogenicity: affects the nervous system, causing paralysis
-
Clostridium perfringens: causes gas gangrene
- Pathogenicity: releases toxins that damage tissue
- Treatment of gas gangrene: surgical debridement, hyperbaric oxygen therapy, antibiotics
-
Clostridium difficile: causes pseudomembranous colitis
- Pathogenicity: produces toxins that disrupt the intestinal lining
- Treatment: metronidazole, vancomycin
Bacillus
- Types: Bacillus anthracis, Bacillus cereus
-
Bacillus anthracis: causes anthrax
- Pathogenicity: produces toxins that cause severe disease
-
Bacillus cereus: causes food poisoning
- Pathogenicity: produces emetic toxin and diarrheal toxin
Neisseriaceae
- Types: Neisseria gonorrhoeae, Neisseria meningitidis
- Neisseria gonorrhoeae (the gonococcus): causes gonorrhea
- Pathogenicity of gonococci: causes urethritis, cervicitis, pelvic inflammatory disease
- Treatment: ceftriaxone
- Neisseria meningitidis (the meningococcus): causes meningococcal meningitis
- Pathogenicity: causes fever, headache, stiff neck, rash, shock
- Treatment: penicillin
Commensal Species
- Types: Staphylococcus epidermidis, Streptococcus salivarius, Lactobacillus spp., Corynebacterium spp.
- Aerobic → facultative anaerobes → obligate anaerobes
Enterobacteria
- Types: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Salmonella enterica, Shigella dysenteriae
- Pathogenicity: causes urinary tract infections, pneumonia, septicaemia, gastroenteritis
- Treatment: ciprofloxacin, ceftriaxone
Bacteroides
- Bacteroides fragilis: found in the gut
- Pathogenicity: causes abscesses, peritonitis
- Treatment: metronidazole
Porphyromonas
- Porphyromonas gingivalis: associated with periodontal disease
-
Pathogenicity: releases enzymes that degrade tissues and cause inflammation
- Involved in the formation of periodontal pockets
- Red complex = Porphyromonas gingivalis + Tannerella forsythia + Trepinema denticola
- Porphyromonas catoniae: found in healthy gingiva
Prevotella
- Prevotella spp.: found in the oral cavity
- Prevotella nigrescens: found in healthy gingiva
- Prevotella intermedia: associated with periodontitis (orange complex)
Fusobacterium
- Types: Fusobacterium nucleatum, Fusobacterium necrophorum
- Pathogenicity: associated with periodontitis, abscesses, and other infections
- Treatment: metronidazole
Spirochaetes
- Types: Treponema pallidum, Trepinema denticola
- Treponema pallidum: causes syphilis
Leptotrichia
- Leptotrichia buccalis: the only member of the genus
- Found in the oral cavity
Mycobacteria
- Types: Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium leprae
- Mycobacterium tuberculosis: causes tuberculosis
- Pathogenicity: infects the lungs leading to coughing, fever, weight loss
- Treatment: isoniazid, rifampicin, pyrazinamide, ethambutol
- Mycobacterium bovis: causes bovine tuberculosis
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Mycobacterium leprae: causes leprosy
- Pathogenicity: causes skin lesions, nerve damage, muscle weakness
- Types: Lepromatous leprosy (multibacillary) and tuberculoid leprosy (paucibacillary)
- Treatment: dapsone, rifampicin, clofazimine
Mycobacteria Other Than TB
- Types: Mycobacterium avium complex (MAC), Mycobacterium kansasii, Mycobacterium marinum
- Pathogenicity: can cause infections in immunocompromised individuals
Legionella
- Most important is legionella pneumophila - causes atypical pneumonia (common in hospitals)
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Legionella pneumophila: found in water sources
- Pathogenicity: causes Legionnaire's disease
- Treatment: azithromycin, levofloxacin
Mycoplasmas
- Mycoplasma pneumoniae: a common cause of pneumonia
- Pathogenicity: causes mild pneumonia, bronchitis
- Treatment: doxycycline, azithromycin
Oral Mycoplasmas
- Types: Mycoplasma salivarium, Mycoplasma orale, Mycoplasma hominis
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Description
Explore the fascinating world of Streptococci and Staphylococci in this microbiology quiz. Learn about various groups, their pathogenicity, treatments, and complications associated with infections. Test your knowledge on their role in human health and disease.
