Podcast
Questions and Answers
Which of the following is a characteristic of Streptococcus pneumoniae?
Which of the following is a characteristic of Streptococcus pneumoniae?
What is a common presentation of Neisseria gonorrhoeae conjunctivitis?
What is a common presentation of Neisseria gonorrhoeae conjunctivitis?
Which bacterial species is most frequently isolated in cases of microbial keratitis (MK) in the UK based on the information provided?
Which bacterial species is most frequently isolated in cases of microbial keratitis (MK) in the UK based on the information provided?
What is the typical morphology and gram stain reaction of Moraxella species?
What is the typical morphology and gram stain reaction of Moraxella species?
Signup and view all the answers
Which patients are described as particularly vulnerable to microbial keratitis (MK)?
Which patients are described as particularly vulnerable to microbial keratitis (MK)?
Signup and view all the answers
What is the primary recommended treatment for patients with severe microbial keratitis (MK), as detailed in the text?
What is the primary recommended treatment for patients with severe microbial keratitis (MK), as detailed in the text?
Signup and view all the answers
What is an accurate description of Neisseria gonorrhoeae based on the text provided?
What is an accurate description of Neisseria gonorrhoeae based on the text provided?
Signup and view all the answers
Besides Haemophilus influenza and Staph. aureus, which other bacterium is specifically mentioned as a cause of anterior segment eye conditions?
Besides Haemophilus influenza and Staph. aureus, which other bacterium is specifically mentioned as a cause of anterior segment eye conditions?
Signup and view all the answers
What is the primary treatment purpose for Polymyxin B?
What is the primary treatment purpose for Polymyxin B?
Signup and view all the answers
Which antibiotic is noted as being effective against infections caused by Pseudomonas?
Which antibiotic is noted as being effective against infections caused by Pseudomonas?
Signup and view all the answers
What type of bacteria is Amikasin particularly effective against?
What type of bacteria is Amikasin particularly effective against?
Signup and view all the answers
Which statement about Tetracycline is correct?
Which statement about Tetracycline is correct?
Signup and view all the answers
What does the presence of resistance in Bacitracin zinc indicate?
What does the presence of resistance in Bacitracin zinc indicate?
Signup and view all the answers
Which organism is primarily responsible for acute microbial keratitis (MK) and can severely scar the cornea?
Which organism is primarily responsible for acute microbial keratitis (MK) and can severely scar the cornea?
Signup and view all the answers
Which bacteria, although of low pathogenicity, can cause severe MK and is sensitive to a wide range of antibiotics?
Which bacteria, although of low pathogenicity, can cause severe MK and is sensitive to a wide range of antibiotics?
Signup and view all the answers
What is the typical causative organism isolated from patients with fungal keratitis?
What is the typical causative organism isolated from patients with fungal keratitis?
Signup and view all the answers
Which type of organism is typically associated with free-living amoebic keratitis (MK)?
Which type of organism is typically associated with free-living amoebic keratitis (MK)?
Signup and view all the answers
Which species are primarily responsible for MK in immunocompromised patients and have been reported in very few cases?
Which species are primarily responsible for MK in immunocompromised patients and have been reported in very few cases?
Signup and view all the answers
What is a key characteristic of Nocardia species in relation to their pathogenicity?
What is a key characteristic of Nocardia species in relation to their pathogenicity?
Signup and view all the answers
Which species has been found occasionally as an isolate in cases of conjunctivitis, though it is more commonly associated with other infections?
Which species has been found occasionally as an isolate in cases of conjunctivitis, though it is more commonly associated with other infections?
Signup and view all the answers
Which of the following statement about Candida species in MK is correct?
Which of the following statement about Candida species in MK is correct?
Signup and view all the answers
What is the primary effective agent against prions mentioned?
What is the primary effective agent against prions mentioned?
Signup and view all the answers
Which sterilization method is NOT primarily affected by heat?
Which sterilization method is NOT primarily affected by heat?
Signup and view all the answers
What is the mechanism of ethylene oxide as a sterilizing agent?
What is the mechanism of ethylene oxide as a sterilizing agent?
Signup and view all the answers
Which type of bacteria is more sensitive to gamma irradiation?
Which type of bacteria is more sensitive to gamma irradiation?
Signup and view all the answers
What characteristic of Deinococcus radiodurans contributes to its high radiation resistance?
What characteristic of Deinococcus radiodurans contributes to its high radiation resistance?
Signup and view all the answers
Which of the following is a consequence of invading micro-organisms?
Which of the following is a consequence of invading micro-organisms?
Signup and view all the answers
Which sterilization method can potentially disrupt biochemical molecules?
Which sterilization method can potentially disrupt biochemical molecules?
Signup and view all the answers
Which spores are known to be more resistant to radiation due to protective proteins?
Which spores are known to be more resistant to radiation due to protective proteins?
Signup and view all the answers
What is the primary aim of therapeutic strategies in treating microbial keratitis?
What is the primary aim of therapeutic strategies in treating microbial keratitis?
Signup and view all the answers
Which antibiotic is specifically NOT suitable for treating Pseudomonas infections?
Which antibiotic is specifically NOT suitable for treating Pseudomonas infections?
Signup and view all the answers
What is an advantage of topical instillation of antimicrobial agents?
What is an advantage of topical instillation of antimicrobial agents?
Signup and view all the answers
How often should antibiotic drops be instilled during the initial management of microbial keratitis?
How often should antibiotic drops be instilled during the initial management of microbial keratitis?
Signup and view all the answers
Cefuroxime is classified as what type of antibacterial agent?
Cefuroxime is classified as what type of antibacterial agent?
Signup and view all the answers
Which of the following antibiotics is used topically in combination with Polymyxin B and neomycin?
Which of the following antibiotics is used topically in combination with Polymyxin B and neomycin?
Signup and view all the answers
What is the preferred method of delivering antibiotics for less systemic toxicity in treating infections?
What is the preferred method of delivering antibiotics for less systemic toxicity in treating infections?
Signup and view all the answers
What is the potential consequence of systemic absorption of eye drops?
What is the potential consequence of systemic absorption of eye drops?
Signup and view all the answers
What is the purpose of using broad spectrum antibiotics in empirical therapy?
What is the purpose of using broad spectrum antibiotics in empirical therapy?
Signup and view all the answers
Why might up to 50% of microbial keratitis (MK) cases be culture negative?
Why might up to 50% of microbial keratitis (MK) cases be culture negative?
Signup and view all the answers
What is typically assessed after isolating the infecting micro-organism?
What is typically assessed after isolating the infecting micro-organism?
Signup and view all the answers
How are antibiotics classified into broad spectrum and narrow spectrum?
How are antibiotics classified into broad spectrum and narrow spectrum?
Signup and view all the answers
What are bacteriostatic antibiotics designed to do?
What are bacteriostatic antibiotics designed to do?
Signup and view all the answers
What does a marked difference in the zones of inhibition compared to the control indicate?
What does a marked difference in the zones of inhibition compared to the control indicate?
Signup and view all the answers
Which of the following is NOT typically tested for antibiotic sensitivity?
Which of the following is NOT typically tested for antibiotic sensitivity?
Signup and view all the answers
What organism is primarily identified in endophthalmitis according to the smear?
What organism is primarily identified in endophthalmitis according to the smear?
Signup and view all the answers
Study Notes
Ocular Microbiology
- Ocular infections are caused by a wide range of microorganisms.
- Many harmless microbes are normally present in the eye, but can become pathogenic.
- Understanding the normal ocular biota and the effects of disinfection/sterilization is important for clinical optometry.
Microbiology of Anterior Segment Eye Conditions
- The ocular surface is sparsely colonized.
- The lid margin and conjunctiva are colonized by Gram-positive bacteria (e.g., coagulase-negative Staphylococci, Corynebacteria, Propionibacterium).
- Gram-negative bacteria are less common.
- The cornea and anterior chamber are considered sterile.
- The normal microbial flora of other mucous membranes is different and more diverse (than the eye).
Obtaining Samples
- Microbial analysis requires scraping the cornea for infection samples.
- Samples may include the bulbar conjunctiva, fornices, and eyelids with moistened cotton swabs/calcium alginate.
- Topical anesthetics are preferable to avoid the effects of preservatives.
Routine Laboratory Protocol
- Direct microscopy is performed first.
- Culture media is inoculated with samples and incubated at 37°C.
- The samples are examined at 24 & 48 hours and if necessary, antibiotic susceptibility tests are performed.
- Staining techniques (e.g., Gram stain) are used to identify bacteria.
Bacterial Growth
- Bacterial growth has four phases (lag, logarithmic, stationary, and decline).
- The stages of growth are important to understand to make a diagnosis.
- Bacteria reproduce asexually by binary fission.
Gaseous Requirements
- Aerobic bacteria require a normal atmosphere.
- Anaerobic bacteria require an oxygen-free environment, and
- Microaerophilic bacteria require less oxygen, as well as facultative anaerobes.
- Some bacteria (fastidious) require additional CO2 for growth.
Bacteriological Media
- Media must contain carbon and nitrogen sources, as well as salts and water.
- Agar is used to solidify the media.
- Different type of media are used to encourage (enrichment), selectively grow specific bacteria, or inhibit other microorganism growth (selective media).
Fungal Growth
- Fungi are easy to grow – often on a simple media or bread in a warm, moisture environment.
Staining for Microscopy
- Various staining methods (Gram stain, Giemsa) detect different microorganisms depending on their characteristics.
- Gram stain identifies Gram-positive (blue) or Gram-negative (red) bacteria.
Microorganism Isolation
- Culturing, methods and specific media (blood agar, chocolate agar, Sabouraud's agar) support the growth of a wide range of bacteria, including fastidious microbes, such as fungi or Neisseria.
Bacteria Causing Ocular Infections
- Table 1 shows various organisms associated with different parts of the eye.
- Organisms differ depending on the age of the patient, site of infection, types of infection.
Ocular Diseases
- Blepharitis (lid margin), conjunctivitis (conjunctiva), keratitis (cornea), etc. are caused by several microbes.
- The causative microorganisms differ for various ocular diseases.
- Table 1 lists the microbes that commonly cause eye conditions with regard to the area of the eye.
Important Microbes
- Staph. aureus and coagulase-negative staphylococci are frequent causes of blepharitis.
- Neisseria gonorrhoeae can cause neonatal conjunctivitis.
- Various other bacteria can lead to various eye conditions.
- Pseudomonas aeruginosa is a common cause of contact lens-associated keratitis.
Microbial Keratitis (MK)
- Microbes can infect the cornea (MK).
- The infections can be caused by various microbes.
- Some microbes are more likely to be present in the environment with regards to where the patients are coming from.
- Culture-guided therapy (using identified microbes and their sensitivities as a guide) can be used to determine the most effective drugs.
- Patients with poor immunity are more susceptible to severe fungal keratitis.
Fungal Microbes
- Fungi, such as Aspergillus and Fusarium, can cause MK.
- Specific fungal infections may result if the patient comes from certain areas or has compromised immunity.
Amoebic Keratitis
- Amoeba can cause MK, including Acanthamoeba species.
- Treatment and prevention methods are crucial because these microbes can be difficult or slow to treat.
Hypopyon, Endophthalmitis
- These are severe anterior segment eye conditions.
- These conditions are often caused by Staph. aureus, Strep. pneumoniae, and other gram negative microbes.
- Samples are taken from aqueous or vitreous (eye fluids) with treatment involving using several types of antimicrobials.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the fundamental aspects of ocular microbiology, particularly focusing on ocular infections caused by various microorganisms. It includes information about the normal microbial flora of the eye, conditions impacting the anterior segment, and methods for obtaining samples for microbial analysis.
