Microbiology Quiz: Gram Staining & Bacteria
22 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the color of Gram (+) bacteria after applying Safranin?

  • Violet (correct)
  • Colorless
  • Green
  • Red or Pink

    • Which of the following is a characteristic of Gram (-) bacteria?

  • Thick peptidoglycan layer
  • More sensitive to penicillin
  • Catalase-negative
  • Presence of outer membrane (correct)

    • What is the virulence factor associated with Shigella spp.?

    Flagella

    The typical temperature range for the growth of Staphylococcus aureus is ______ °C.

    <p>15-45</p> Signup and view all the answers

    What type of hemolysis does Streptococcus pyogenes produce?

    <p>Beta-hemolysis</p> Signup and view all the answers

    The antibiotic treatment for Clostridium botulinum is ______.

    <p>Metronidazole</p> Signup and view all the answers

    Match the following bacterial species with their corresponding diseases:

    <p>Escherichia coli = Urinary Tract Infection (UTI) Streptococcus pneumoniae = Pneumonia Clostridium tetani = Tetanus Bacillus anthracis = Anthrax</p> Signup and view all the answers

    All Streptococcus species are catalase-positive.

    <p>False</p> Signup and view all the answers

    S.epidermidis is coagulase-positive.

    <p>False</p> Signup and view all the answers

    What is the mechanism of action (MOA) of endotoxins?

    <p>Can cause fever, inflammation, and septic shock</p> Signup and view all the answers

    What is a major cause of nosocomial infections associated with Staphylococcus aureus?

    <p>Tampon use and surgery</p> Signup and view all the answers

    What treatment is commonly used for Haemophilus influenza infections?

    <p>Cefotaxime</p> Signup and view all the answers

    What is the primary disease caused by Bordetella pertussis?

    <p>Whooping cough</p> Signup and view all the answers

    Haemophilus ducreyi causes soft chancres.

    <p>True</p> Signup and view all the answers

    The DOC for treating Haemophilus vaginalis infections is ___.

    <p>Metronidazole</p> Signup and view all the answers

    Which organism is known to cause cat-scratch disease?

    <p>Bartonella henselae</p> Signup and view all the answers

    What is the vector for Leishmania tropica?

    <p>Sandfly</p> Signup and view all the answers

    Yersinia pestis does not cause plague.

    <p>False</p> Signup and view all the answers

    What is the primary mode of transmission for Brucella spp.?

    <p>All of the above</p> Signup and view all the answers

    What is the treatment for Enterocolitis caused by Yersinia enterocolitica?

    <p>ORS, Fluoroquinolones, and Cotrimoxazole</p> Signup and view all the answers

    Coccidioidomycosis is also known as ___.

    <p>San Joaquin Valley Fever</p> Signup and view all the answers

    Cryptococcus neoformans can be identified using India ink staining.

    <p>True</p> Signup and view all the answers

    Study Notes

    Basics of Microbial Diversity in Prokaryotes

    • Prokaryotes are classified into two main groups based on their cell wall characteristics: Gram-positive and Gram-negative.
    • Gram staining involves a series of steps that differentiate bacteria based on their cell wall structure.

    Gram Staining Procedures

    • Crystal Violet: Stains both Gram-positive and Gram-negative bacteria violet.
    • Iodine: Acts as a mordant, intensifying the violet color in all bacteria.
    • Alcohol:
      • For Gram-positive: retains violet color.
      • For Gram-negative: results in colorless outcome.
    • Safranin:
      • For Gram-positive: retains violet color.
      • For Gram-negative: stains red or pink.

    Features of Cell Wall

    • Gram-positive:
      • Thick peptidoglycan layer.
      • Contains teichoic acids for rigidity.
      • Higher resistance to physical disruption.
      • More sensitive to penicillin and lysozyme.
    • Gram-negative:
      • Thin peptidoglycan layer.
      • Contains an outer membrane with lipopolysaccharides (LPS).
      • Less sensitive to antibiotics like penicillin.

    Microbial Morphology

    • Morphology includes shapes like cocci (spherical), bacilli (rod-shaped), spirilla (spiral), and pleomorphic.

    Virulence Factors

    • Motility: Flagella provide mobility in pathogens such as Shigella, Campylobacter, and Helicobacter.
    • Toxins:
      • Endotoxins: Part of the Gram-negative outer membrane; stable at high temperatures, generally less potent, pyrogenic.
      • Exotoxins: Secreted by both Gram-positive and Gram-negative; unstable at high temperatures, highly potent, and target specific cells.

    Bacterial Spores

    • Dormant structures allowing survival in extreme conditions.
    • Highly resistant to environmental stressors such as heat and desiccation, can germinate under favorable conditions.

    Gram-positive Cocci

    • Catalase test: Identifies Staphylococcus spp. (+) produce bubbles; Streptococcus spp. (-) do not.
    • Staphylococcus aureus:
      • Characteristics: Forms grape-like clusters; coagulase-positive.
      • Associated with nosocomial infections and Toxic Shock Syndrome.
      • Key diseases: Scalded Skin Syndrome and Food Poisoning.
    • Staphylococcus epidermidis:
      • Coagulase-negative; opportunistic pathogen.
      • Common infections: Prosthetic valve endocarditis, UTIs.
    • Staphylococcus saprophyticus:
      • Novobiocin-resistant; common cause of UTIs in sexually active women.

    Streptococcus Characteristics

    • Morphology: Spherical, appear in chains; catalase-negative.
    • Alpha-hemolytic: Partial hemolysis, includes S. pneumoniae (causes pneumonia) and S. viridans (part of oral flora).
    • Beta-hemolytic: Complete hemolysis; includes S. pyogenes (causes strep throat) and S. agalactiae (neonatal infections).
    • Gamma-hemolytic: Non-hemolytic; includes enterococci linked to UTIs and endocarditis.

    Lancefield Grouping

    • A method for classifying streptococci based on cell wall antigens.
    • Group A: S. pyogenes, causes pharyngitis and scarlet fever.
    • Group B: S. agalactiae, significant in neonatal infections.

    Gram-positive Bacilli

    • Includes spore-forming (Bacillus, Clostridium) and non-spore-forming genera.
    • Bacillus anthracis: Causes anthrax, has unique amino acid capsule; used in biowarfare.
    • Clostridium spp.:
      • C. botulinum: Causes flaccid paralysis, produces lethal neurotoxin.
      • C. tetani: Causes spastic paralysis; preventative vaccines available.

    Non-spore Forming Gram-positive Bacilli

    • Corynebacterium diphtheriae: Aerobic, non-motile, causes diphtheria.
    • Listeria monocytogenes: Can cause serious infections during pregnancy.

    Conclusion

    • Understanding the classification, morphology, pathogenic mechanisms, and associated diseases of prokaryotic microorganisms is essential for identifying and treating bacterial infections effectively.### Diphtheria
    • Produces diphtheria toxin and commonly infects the upper respiratory tract.
    • Symptoms include a sore throat and can be screened using the Schick test.
    • Diagnosed using Loeffler’s slant medium.
    • Prophylactic treatment includes the DTP vaccine.
    • Treatment options: Erythromycin and Penicillin G.

    Listeria monocytogenes

    • Exhibits tumbling motility and is facultatively anaerobic.
    • Produces hemolysin and ferments sugars, resulting in acid production.
    • Causes listeriosis and neonatal meningitis.
    • Treatment: Cotrimoxazole and Ampicillin.

    Lactobacillus

    • Located in the vagina, intestinal tract, and oral cavity.
    • Commercially used in the production of sauerkraut, pickles, buttermilk, and yogurt.

    Non-Sporing Forming Bacteria

    • Erysipelothrix rhusiopathiae: Occupational pathogen; causes seal finger disease; treated with Penicillin.
    • Actinomyces israelii: Causes actinomycosis; noted for skin lesions and pus; treat with surgical removal.
    • Nocardia asteroides: Causes chronic pulmonary infections and mycetoma; treated with Co-trimoxazole.
    • Propionibacterium acne: Main cause of acne; involved in Swiss cheese fermentation.

    Gram (-) Cocci

    • Neisseria spp.:
      • N.meningitidis: Causes meningitis and meningococcemia; prophylaxis with Rifampicin and Ciprofloxacin; treatment with Ciprofloxacin.
      • N.gonorrhea: Causes gonorrhea and PID; grows in enriched media; treated with Ceftriaxone and Doxycycline.
      • Moraxella catarrhalis: Causes otitis media and respiratory infections; a Gram-negative diplococcus.

    Gram (-) Bacilli

    Enterobacteriaceae

    • Includes E. coli, Klebsiella pneumoniae, Salmonella spp., Shigella dysenteriae, etc.
    • E.coli: Gram-negative, motile; causes UTI, neonatal meningitis, and hospital-acquired pneumonia; treated with Cotrimoxazole and Quinolones.
    • E.coli classified into different pathotypes like EPEC, ETEC, EIEC, and EHEC.

    Salmonella

    • Salmonella typhi: Causes typhoid fever; diagnosed with the Widal test; treated with Ciprofloxacin or Ceftriaxone.
    • Salmonella enteritidis: Causes gastroenteritis; Salmonella choleraesius: associated with septicemia.

    Shigella dysenteriae

    • Non-motile, non-spore forming; known for causing dysentery; treated with Cotrimoxazole and Quinolones.

    Vibrio

    • Vibrio cholerae: Responsible for cholera; virulence factor includes cholera toxin; treated with Tetracycline and Oral Rehydration Salt.
    • Helicobacter pylori: Microaerophilic organism; causes gastritis and ulcers; treated with multidrug therapy including Bismuth compounds.

    Pseudomonas aeruginosa

    • Gram-negative rod, opportunistic pathogen; characterized by a sweet grape-like odor; detected based on blue-green fluorescing colonies.
    • Treatment includes anti-pseudomonal penicillins and aminoglycosides.

    Fungi

    • Fungi are eukaryotic, acquiring nutrients through absorption; reproduce sexually and asexually.
    • Classified into Zygomycota, Microsporidia, Ascomycota, and Basidiomycota.

    Fungal Diseases

    • Superficial Mycoses: Include diseases such as Black Piedra and Pityriasis versicolor.
    • Cutaneous Mycoses: Dermatophytes such as Tinea pedis and Tinea corporis.
    • Systemic Mycoses: Diseases like Coccidioidomycosis and Cryptococcosis; treated with Amphotericin B or Fluconazole.

    Algae

    • Algae are unicellular or multicellular photosynthetic organisms; can reproduce sexually and asexually.
    • Thallus refers to the body of multicellular algae; seaweeds have structures such as holdfasts for anchoring.

    Conclusions

    • Importance of understanding various bacterial and fungal pathogens, their disease manifestations, and treatment modalities.
    • Knowledge of microbial diversity helps in diagnostics and preventing infectious diseases in clinical settings.### Algae Structure and Support
    • Stipes are stem-like, hollow structures providing support, unlike woody plant stems.
    • Blades are leaf-like structures extending from the stipe.
    • Surrounding water supports the algae; some have gas-filled bladders called pneumatocysts for buoyancy.

    Algae Reproduction

    • Asexual reproduction occurs through mitosis, producing identical offspring.
    • Sexual reproduction involves the fusion of gametes, promoting genetic diversity.

    Protozoa Overview

    • Protozoa belong to the kingdom Protista, mostly unicellular but some form colonies.
    • Classified by locomotion:
      • Amebas use pseudopodia (false feet).
      • Flagellates utilize whiplike flagella.
      • Ciliates employ hairlike cilia.
      • Sporozoans lack motility, having no specialized locomotion structures.

    Protozoan Infections and Lifecycle

    • Diagnosed by observing various developmental stages including trophozoites (motile, feeding stage) and dormant cysts.
    • Infections generally acquired through ingestion/inhalation of cysts, or bites from infected arthropods.
    • Rarely, trophozoites serve as the infective stage due to fragility.

    Protozoa Reproduction

    • Asexual reproduction includes:
      • Fission: simple cell division.
      • Budding: new organism forms from a part of a cell.
      • Schizogony: multiple fission, leading to several daughter cells.
    • Sexual reproduction involves the formation of gametes and zygote formation (fusion of two gametes).

    Types of Hosts in Protozoa

    • Definitive host harbors the sexually mature form of a parasite.
    • Paratenic host carries the parasite in a non-developing form, keeping it viable for infection.
    • Intermediate host supports the asexual or larval stage of the parasite.

    Groups of Protozoa

    • Amoebas: Free-living in water; move by pseudopods.

      • Entamoeba histolytica causes amebiasis via fecal-oral transmission; diagnosed through fecalysis.

    • Flagellates: Lack mitochondria and possess multiple flagella.

      • Giardia lamblia causes giardiasis; commonly transmitted fecal-orally.
      • Trichomonas vaginalis causes trichomoniasis; transmitted sexually.
      • Leishmania spp. are zoonotic; transmitted by sandflies causing various leishmaniasis forms.
      • Trypanosoma cruzi causes Chagas' disease, vector is the kissing bug.
      • Trypanosoma brucei causes sleeping sickness; transmitted by tsetse fly.

    • Ciliates: Notable for their cilia.

      • Balantidium coli, largest protozoan parasite, causes balantidiasis; reservoirs include pigs.

    • Sporozoans: Lifecycle involves sexual and asexual cycles.

      • Mosquito is the definitive host for Plasmodium spp., which cause malaria:
        • P.falciparum: deadliest and most common.
        • P.vivax: benign tertian malaria.
        • P.ovale and P.malariae also cause malaria.

    Malaria Prophylaxis and Treatment

    • Prophylactic drugs include chloroquine; alternatives for drug-resistant strains are quinine + fansidar.
    • Severe P.falciparum malaria treatment involves quinidine.

    Other Protozoal Infections

    • Toxoplasma gondii: causes toxoplasmosis; associated with cat feces.
    • Isospora belli: causes isosporiasis; particularly harmful in immunocompromised individuals.
    • Blastocystis hominis: resembles protozoan yeast; transmitted fecal-orally and treated with metronidazole.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Microbial Diversity: Prokaryotes PDF

    Description

    Test your knowledge on Gram staining techniques and bacterial characteristics with this microbiology quiz. It covers important details like the color changes in Gram-positive and Gram-negative bacteria, virulence factors, and growth conditions for notable bacteria. Perfect for students studying microbiology!

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser