Gram-Negative Cocci and Neisseria

Gram-Negative Cocci

• Gram-negative cocci are spherical bacteria that stain pink or red during Gram staining.
• Gram-negative cocci can appear in pairs (diplococci), tetrads, or clusters.
• Gram-negative cocci are fastidious, requiring enriched media and special growth conditions.
• Gram-negative cocci are characterized by a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides.
• Gram-negative cocci primarily require aerobic conditions for optimal growth.
• Incubation at 35-37°C with 5-10% CO2 is necessary for the growth of gram-negative cocci.
• Gram-negative cocci grow well on blood agar, chocolate agar, and other nutrient-rich media.
• Selective media like Thayer-Martin agar can be used to isolate and differentiate specific gram-negative species.

Neisseria

• Neisseria species, such as N. gonorrhoeae and N. meningitidis, cause significant infections like gonorrhea and meningococcal disease.
• Neisseria are Gram-negative diplococci, often appearing in a "kidney bean" shape.
• Neisseria species are fastidious, requiring enriched media like blood agar or chocolate agar for optimal growth.
• The oxidase test is a key biochemical test used to identify Neisseria species.

Diagnosis of Neisseria Meningitidis

• Samples should be collected from the nasopharynx or cerebrospinal fluid (CSF) for diagnosis.
• Gram staining reveals characteristic Gram-negative diplococci, often with a "coffee bean" appearance.
• Cultivate bacteria on selective media like Thayer-Martin agar and confirm species identification using biochemical tests.
• CSF analysis involves a lumbar puncture and examination for turbidity, cell count (mainly polymorphs), and chemical analysis (protein and glucose).
• Latex agglutination is used to detect capsular antigens in the CSF supernatant.
• Neisseria meningitidis carriers are diagnosed from a nasopharyngeal swab cultured on Thayer-Martin agar.

Moraxella

• Moraxella are aerobic, gram-negative cocci commonly appearing in pairs or tetrads.
• Moraxella species are opportunistic pathogens, particularly M. catarrhalis and M. lacunata.
• Moraxella catarrhalis causes respiratory tract infections, conjunctivitis, and occasionally more invasive infections.

Diagnosis of Moraxella Catarrhalis

• M. Catarrhalis grows on blood agar or chocolate agar, forming smooth, grayish, non-hemolytic colonies.

Key Differences between N. meningitidis and N. gonorrhoeae

• N. meningitidis: has a capsule, ferments glucose and maltose, causes meningitis, transmits via droplets.
• N. gonorrhoeae: lacks a capsule, ferments glucose only, causes gonorrhea, transmits sexually.

Gram-Negative Cocci

• Gram-negative cocci are spherical bacteria that stain pink or red when subjected to the Gram staining procedure.
• This indicates that they have a thin peptidoglycan layer and an outer membrane with lipopolysaccharides.
• They can appear in pairs (diplococci), tetrads, or irregular clusters, depending on the species.
• They are fastidious organisms, requiring specialized culture media and growth conditions.

Medically Relevant Species

• Neisseria: Includes N. gonorrhoeae and N. meningitidis, which cause gonorrhea and meningococcal disease, respectively.
  • N. gonorrhoeae is transmitted sexually.
  • N. meningitidis is transmitted through respiratory droplets.
  • Moraxella: Opportunistic pathogens like M. catarrhalis can cause respiratory infections, especially in immunocompromised individuals.
    • M. catarrhalis is a common respiratory pathogen that can lead to sinusitis, bronchitis, and pneumonia.
• Acinetobacter: Multidrug-resistant species like A. baumannii are major causes of nosocomial infections in healthcare settings.

Diagnosis

• Culture: Gram-negative cocci can be grown on enriched media like blood agar or chocolate agar, and sometimes on selective media like Thayer-Martin agar.
• Biochemical Tests:
  • Oxidase Test: Determines the presence of cytochrome c oxidase, a key characteristic of many Gram-negative cocci, including Neisseria and Moraxella species.
  • Carbohydrate Utilization: Evaluates a bacteria's ability to ferment or oxidize different carbohydrates, providing insights into their metabolic profiles and species identification.
• Serological Tests: Detect bacterial antigens or antibodies to aid in diagnosis.

Neisseria Species

• Key Pathogenic Species: N. gonorrhoeae and N. meningitidis.
• Morphology: Neisseria are Gram-negative diplococci, often described as "coffee bean" or "kidney bean" shaped.
• Virulence Factors: Pili, outer membrane proteins, and capsular polysaccharides contribute to the virulence of these bacteria.

Diagnosis of Neisseria Meningitidis

• Sample Collection: Collect samples from the nasopharynx or cerebrospinal fluid (CSF).
• Gram Staining: Observe gram-negative diplococci with a typical "coffee bean" appearance.
• Culture: Grow the bacteria on selective media like modified Thayer-Martin agar.
• Biochemical Tests: Perform additional tests to confirm the species identification.

CSF Collection and Analysis

• Collect CSF by lumbar puncture.
• Divide CSF into three tubes:
  • Tube 1: Microbiological analysis.
  • Tube 2: Chemical analysis for protein and glucose.
  • Tube 3: White cell count.
• Tube 1 Analysis:
  • Centrifuge the CSF.
  • Aspirate the supernatant for detection of capsular antigen.
  • Analyze the deposit for Gram staining and culture.

Diagnosis of N. Meningitidis Carriers

• Collect nasopharyngeal swabs (West swabs).
• Culture on Thayer-Martin medium.
• Perform the oxidase test.

Moraxella Species

• Medically Relevant Species: M. catarrhalis and M. lacunata.
• Morphology: Moraxella species are aerobic, gram-negative cocci that often appear in pairs or tetrads.
• Clinical Significance: Moraxella species are opportunistic pathogens that can cause respiratory tract infections, conjunctivitis, and rarely, more invasive infections.

Diagnosis of Moraxella Catarrhalis

• Culture: Grow M. catarrhalis on blood agar or chocolate agar.
• Colony Morphology: Colonies are smooth, grayish, and non-hemolytic.

Gram-Negative Cocci

• Gram-negative cocci are spherical bacteria that stain pink or red when subjected to Gram staining
• Gram-negative cocci can appear in pairs (diplococci), tetrads, or irregular clusters depending on the species
• Gram-negative cocci are fastidious organisms that require specialized culture media and growth conditions to thrive

Medically Relevant Gram-Negative Cocci

• Gram-negative cocci are widely distributed in nature and can colonize various sites in the human body
• They are clinically significant as they can cause serious infections, particularly in immunocompromised individuals and hospital settings
• Certain species, such as Neisseria gonorrhoeae and Neisseria meningitidis, are known to cause gonorrhea and meningitis, respectively

Neisseria Species

• Key pathogenic Neisseria species include N. gonorrhoeae, the causative agent of gonorrhea, and N. meningitidis, responsible for meningococcal disease
• Neisseria are Gram-negative diplococci, often described as "coffee bean" or "kidney bean" shaped
• Neisseria species are fastidious, requiring enriched media like blood agar or chocolate agar for optimal growth

Diagnosis of Neisseria Meningitidis

• Collect samples from the nasopharynx or cerebrospinal fluid for diagnosis of Neisseria meningitidis
• Perform Gram staining to observe the characteristic Gram-negative diplococci with the typical "coffee bean" appearance
• Grow the bacteria on selective media like modified Thayer-Martin agar and perform biochemical tests to confirm the species

Diagnosis of N. meningitidis Carriers

• The specimen used is a nasopharyngeal swab (West swab) that is cultured on Thayer-Martin medium and incubated at 37°C for 24 hours in 5-10% CO2 conditions.
• The oxidase test can be used to confirm the presence of the enzyme cytochrome c oxidase, an important component of the electron transport chain in certain bacteria

N. meningitidis vs N. gonorrhoeae

• N. meningitidis has a capsule and ferments glucose and maltose, while N. gonorrhoeae does not have a capsule and only ferments glucose

Moraxella Species

• Moraxella species are aerobic, Gram-negative cocci that often appear in pairs or tetrads
• The most clinically significant Moraxella species are M. catarrhalis and M. lacunata
• Moraxella can cause respiratory tract infections, conjunctivitis, and rarely, more invasive infections

Diagnosis of Moraxella catarrhalis

• Grow M. catarrhalis on blood agar or chocolate agar. Colonies are smooth, grayish, and non-hemolytic.

Gram-Negative Cocci

• Gram-negative cocci are spherical bacteria that stain pink or red when subjected to the Gram staining procedure.
• They can appear in pairs (diplococci), tetrads, or irregular clusters.
• They are fastidious organisms that need specialized culture media and growth conditions to thrive.
• Gram-negative cocci have a thin peptidoglycan layer and an outer membrane with lipopolysaccharides.

Epidemiology and Clinical Significance

• Gram-negative cocci are found everywhere in nature.
• Some species can cause serious infections, particularly in immunocompromised individuals and hospital settings.
• Neisseria gonorrhoeae causes gonorrhea.
• Neisseria meningitidis causes meningitis.
• Moraxella catarrhalis is a common respiratory pathogen that can cause sinusitis, bronchitis, and pneumonia.

Culture Requirements

• Aerobic Growth: Gram-negative cocci generally require aerobic conditions for optimal growth and cultivation.
• Incubation Conditions: Incubation at 35-37°C with 5-10% CO2 is commonly required.
• Enriched Media: They grow well on blood agar, chocolate agar, or other nutrient-rich media.
• Selective Media: Selective media, such as Thayer-Martin agar, can isolate specific species.

Biochemical Tests

• Oxidase Test: Determines the presence of the enzyme cytochrome c oxidase, a key characteristic of many Gram-negative cocci, including Neisseria and Moraxella species.
• Carbohydrate Utilization: Evaluates the bacteria's ability to ferment or oxidize different carbohydrates.

Serological Tests

• Antigen Detection: Detect bacterial antigens for rapid diagnosis.
• Antibody Detection: Measure the body's immune response by detecting specific antibodies.

Medically Important Gram-Negative Cocci

• Neisseria: Includes N. gonorrhoeae (gonorrhea) and N. meningitidis (meningitis).
• Moraxella: Opportunistic pathogens like M. catarrhalis (respiratory infections) and M. lacunata (conjunctivitis).
• Acinetobacter: Multidrug-resistant species like A. baumannii cause nosocomial infections.

Neisseria Species

• Key Pathogenic Neisseria Species: N. gonorrhoeae and N. meningitidis.
• Morphology and Staining: Gram-negative diplococci, often described as "coffee bean" or "kidney bean" shaped.
• Growth Requirements: Fastidious, requiring enriched media like blood agar or chocolate agar.
• Virulence Factors: Pili, outer membrane proteins, and capsular polysaccharides.

Diagnosis of Neisseria Meningitidis

• Sample Collection: Nasopharyngeal swab or cerebrospinal fluid (CSF).
• Gram Staining: Gram-negative diplococci with the typical "coffee bean" appearance.
• Culture-Based Identification: Grow on selective media like modified Thayer-Martin agar, use biochemical tests to confirm the species.

Diagnosis of N. meningitidis Carriers

• Sample Collection: Nasopharyngeal swab.
• Culture: Thayer-Martin medium, incubated at 37°C for 24 hours with 5-10% CO2.

Oxidase Test

• Used to identify bacteria that produce the enzyme cytochrome c oxidase.
• Oxidase-positive bacteria: Neisseria, Pseudomonas, and Vibrio

Neisseria meningitidis vs. N. gonorrhoeae

• N. meningitidis: Has a capsule. Ferments glucose and maltose; causes meningitis; transmission by droplet spread.
• N. gonorrhoeae: No capsule. Ferments glucose; causes gonorrhea; transmission sexually.

Moraxella Species

• Moraxella Species: Aerobic, gram-negative cocci that often appear in pairs or tetrads.
• Medically Relevant Species: M. catarrhalis and M. lacunata.
• Opportunistic Pathogens: Moraxella species can cause respiratory tract infections, conjunctivitis, and rarely, more invasive infections.

Diagnosis of Moraxella Catarrhalis

• Culture: Grow on blood agar or chocolate agar.
• Colonies: Smooth, grayish, and non-hemolytic.

Gram-Negative Cocci

• Gram-negative cocci stain** pink or red** in Gram staining due to their thin peptidoglycan layer.
• They have a characteristic** bean-shape** or coffee bean-like appearance under the microscope.
• They can appear in pairs (diplococci), tetrads, or irregular clusters.
• They are fastidious organisms, meaning they require** specialized media** and growth conditions for cultivation.

Culture Requirements

• Aerobic growth: They generally require aerobic conditions for optimal growth.
• Incubation: Optimal growth happens at 35-37°C with 5-10% CO2.
• Media: They grow well on blood agar, chocolate agar, or enriched media.
• Selective media: Thayer-Martin agar can be used to isolate specific gram-negative cocci.

Biochemical Tests

• Oxidase test: Determines the presence of cytochrome c oxidase, a key characteristic of many Neisseria and Moraxella species.
• Carbohydrate utilization: Evaluates the bacteria's ability to ferment or oxidize different carbohydrates, providing insights into their metabolic profiles.

Serological Tests

• Antigen detection: Serological tests can detect bacterial antigens, providing rapid diagnosis of infections.
• Antibody detection: Measuring the body's immune response by detecting specific antibodies can aid diagnosis.

Medically Important Gram-Negative Cocci

• Neisseria: Includes N. gonorrhoeae (causes gonorrhea) and N. meningitidis (causes meningococcal disease).
• Moraxella: Opportunistic pathogens like M. catarrhalis can cause respiratory infections.
• Acinetobacter: Multidrug-resistant species like A. baumannii are major causes of nosocomial infections in healthcare settings.

Neisseria Species

• Pathogenic species: N. gonorrhoeae and N. meningitidis are key pathogenic species.
• Morphology and staining: Neisseria are gram-negative diplococci, often described as "coffee bean" or "kidney bean" shaped.
• Growth requirements: They are fastidious and require enriched media like blood agar or chocolate agar for optimal growth.
• Virulence factors: Pili, outer membrane proteins, and capsular polysaccharides contribute to their virulence.

Diagnosis of Neisseria Meningitidis

• Sample collection: Collect samples from nasopharynx or cerebrospinal fluid (CSF) for diagnosis.
• Gram staining: Perform Gram staining to observe the characteristic gram-negative diplococci with the typical "coffee bean" appearance.
• Culture-based identification: Grow the bacteria on selective media like modified Thayer-Martin agar and perform biochemical tests to confirm the species.

Diagnosis of N. meningitidis Carriers

• Specimen: A nasopharyngeal swab is collected and cultured on Thayer-Martin medium at 37°C for 24 hours with 5-10% CO2 conditions.

Oxidase Test

• Purpose: The oxidase test differentiates between various groups of Gram-negative bacteria based on the presence of cytochrome c oxidase.
• Oxidase-positive bacteria: Include species such as Neisseria, Pseudomonas, and Vibrio.

Comparison of N. meningitidis and N. gonorrhoeae

Moraxella Species

• Gram-negative cocci: Moraxella species are aerobic, gram-negative cocci that often appear in pairs or tetrads.
• Medically relevant species: M. catarrhalis and M. lacunata are the most clinically significant.
• Opportunistic pathogens: They can cause respiratory tract infections, conjunctivitis, and rarely, more invasive infections.
• M. catarrhalis: A common pathogen that can lead to respiratory tract infections.

Diagnosis of Moraxella Catarrhalis

• Culture: Grow M. catarrhalis on blood agar or chocolate agar. Colonies are smooth, grayish, and non-hemolytic.

Gram-Negative Cocci

• Gram-negative cocci are spherical bacteria that stain pink or red when subjected to the Gram stain.
• They can appear in pairs, tetrads, or irregular clusters.
• They have a thin peptidoglycan layer and an outer membrane with lipopolysaccharides.
• They are fastidious organisms requiring specialized culture media and growth conditions.
• They are widely distributed in nature and can colonize various sites in the human body.
• Certain species cause serious infections, particularly in immunocompromised individuals and hospital settings.

Medically Important Gram-Negative Cocci

• Neisseria: Includes N. gonorrhoeae (causes gonorrhea) and N. meningitidis (causes meningococcal disease).
• Moraxella: Opportunistic pathogens like M. catarrhalis can cause respiratory infections.
• Acinetobacter: Multidrug-resistant species like A. baumannii are major causes of nosocomial infections.

Neisseria Species

• Key Pathogenic Species: N. gonorrhoeae and N. meningitidis.
• Morphology and Staining: Appear as Gram-negative diplococci often described as "coffee bean" or "kidney bean" shaped.
• Growth Requirements: Fastidious, requiring enriched media like blood agar or chocolate agar for optimal growth.

Diagnosis of Neisseria Meningitidis

• Sample Collection: Collect samples from the nasopharynx or cerebrospinal fluid.
• Gram Staining: Observe the characteristic Gram-negative diplococci.
• Culture-Based Identification: Grow bacteria on selective media like modified Thayer-Martin agar and perform biochemical tests.

Diagnosis of N. meningitidis Carriers

• The specimen used is a nasopharyngeal swab cultured on Thayer-Martin medium.

Oxidase Test

• A biochemical test used to identify bacteria that produce the enzyme cytochrome c oxidase.

Moraxella Species

• Aerobic, gram-negative cocci that often appear in pairs or tetrads.
• M. catarrhalis and M. lacunata are clinically significant.
• M. catarrhalis is a common pathogen that can lead to respiratory tract infections.

Diagnosis of Moraxella Catarrhalis

• Grow M. catarrhalis on blood agar or chocolate agar.
• Colonies are smooth, grayish, and non-hemolytic.

Gram-Negative Cocci

• Gram-negative cocci are spherical bacteria that stain pink or red when subjected to the Gram staining procedure.
• They have a thin peptidoglycan layer and an outer membrane with lipopolysaccharides.
• They appear in pairs (diplococci), tetrads, or irregular clusters depending on the species.

Culture Requirements

• Gram-negative cocci are fastidious organisms that require specialized culture media and growth conditions.
• They require aerobic conditions for optimal growth.
• An incubation temperature of 35-37°C with 5-10% CO2 is commonly required.
• They grow well on blood agar, chocolate agar, or other nutrient-rich media.
• Selective media, such as Thayer-Martin agar, can be used to isolate and differentiate specific Gram-negative cocci species.

Medically Important Gram-Negative Cocci

• Medically relevant Gram-negative cocci include Neisseria, Moraxella, and Acinetobacter.
• The most clinically significant Neisseria species are N. gonorrhoeae, the causative agent of gonorrhea, and N. meningitidis, responsible for meningococcal disease.
• Moraxella species are opportunistic pathogens that can cause respiratory infections, conjunctivitis, and rarely, more invasive infections.
• Acinetobacter baumannii is a multidrug-resistant species that is a major cause of nosocomial infections in healthcare settings.

Neisseria Species

• Neisseria species are fastidious, requiring enriched media for optimal growth, such as blood agar or chocolate agar.
• They are Gram-negative diplococci, often described as "coffee bean" or "kidney bean" shaped.
• They are oxidase positive and ferment glucose and maltose with acid only.

Diagnosis of Neisseria Meningitidis

• Samples are collected from the nasopharynx or cerebrospinal fluid (CSF) for diagnosis.
• The CSF is typically high in polymorphs.
• The CSF is centrifuged, and the supernatant is used to detect capsular antigens.
• The deposit is used to prepare smears stained with Gram to demonstrate gram-negative diplococci, intracellular and extracellular.
• The CSF is cultured on chocolate agar or Thayer Martin medium at 37°C for 24 hours with 5-10% CO2.
• N. meningitidis carriers are diagnosed by culturing a nasopharyngeal swab on Thayer Martin medium, incubated at 37°C for 24 hours with 5-10% CO2.

Oxidase Test

• The oxidase test identifies bacteria that produce the enzyme cytochrome c oxidase.
• This enzyme allows bacteria to use oxygen as the terminal electron acceptor in aerobic respiration.
• Oxidase-positive bacteria include Neisseria, Pseudomonas, and Vibrio.

Moraxella Species

• The most clinically significant Moraxella species are M. catarrhalis and M. lacunata.
• Moraxella catarrhalis is a common pathogen that can lead to respiratory tract infections, conjunctivitis and other infections.

Diagnosis of Moraxella Catarrhalis

• Moraxella catarrhalis is cultured on blood agar or chocolate agar, forming smooth, grayish, non-hemolytic colonies.

Defining Characteristics

• Gram-negative cocci have a thin peptidoglycan layer
• Gram-negative cocci stain pink or red when using the Gram staining procedure
• Gram-negative cocci are spherical bacteria

Cell Arrangement

• These bacteria can appear in pairs (diplococci), tetrads, or irregular clusters

Culture Requirements

• Gram-negative cocci are fastidious organisms
• They require specialized culture media and growth conditions to thrive
• Aerobic conditions are required for optimal growth
• They require an incubation temperature of 35-37°C with 5-10% CO2
• They grow well on blood agar, chocolate agar, or other nutrient-rich media

Epidemiology and Clinical Significance

• Gram-negative cocci can cause serious infections, particularly in immunocompromised individuals
• Neisseria gonorrhoeae is known to cause gonorrhea
• Neisseria meningitidis is known to cause meningitis
• Moraxella catarrhalis can cause sinusitis, bronchitis, and pneumonia

Morphological Characteristics

• Gram-negative cocci are small, spherical bacteria
• They often appear in pairs or clusters
• They have a characteristic bean-shaped or coffee bean-like appearance under the microscope
• They have a thin peptidoglycan layer in their cell wall and an outer membrane with lipopolysaccharides

Staining Properties

• Gram-negative cocci appear as pink or red-colored cells when subjected to the Gram staining technique
• The color is in contrast to the purple-stained gram-positive bacteria

Biochemical Tests

• Oxidase Test: Determines the presence of the enzyme cytochrome c oxidase, which is a key characteristic of many Gram-negative cocci species
• Carbohydrate Utilization: Evaluates a bacteria's ability to ferment or oxidize different carbohydrates

Serological Tests

• Antigen Detection: Serological tests can detect bacterial antigens and provide a rapid diagnosis
• Antibody Detection: Measuring the body's immune response by detecting specific antibodies can aid diagnosis

Medically Important Gram Negative Cocci

• Neisseria: Includes pathogenic species like N. gonorrhoeae and N. meningitidis, which cause serious infections like gonorrhea and meningococcal disease.
• Moraxella: Opportunistic pathogens such as M. catarrhalis can cause respiratory infections, especially in immunocompromised individuals, like sinusitis, bronchitis, and pneumonia.
• Acinetobacter: Multidrug-resistant species like A. baumannii can cause nosocomial infections.

Neisseria Species

• Key pathogenic Neisseria species: N. gonorrhoeae (causes gonorrhea) and N. meningitidis (responsible for meningococcal disease)
• Morphology and Staining: Neisseria are Gram-negative diplococci, often described as "coffee bean" or "kidney bean" shaped.
• Growth Requirements: Neisseria species are fastidious and require enriched media like blood agar or chocolate agar for optimal growth.

Diagnosis of Neisseria Meningitidis

• Sample Collection: Collect samples from the nasopharynx or cerebrospinal fluid (CSF) for diagnosis
• Gram Staining: Perform Gram staining to observe the characteristic Gram-negative diplococci (which have a "coffee bean" appearance)
• Culture-Based Identification: Grow the bacteria on selective media like modified Thayer-Martin agar and perform biochemical tests to confirm the species.

CSF Collection

• Collect CSF from the spinal fluid (lumbar puncture) under aseptic conditions
• Divide the CSF into three tubes:
  • Tube 1 is used for microbiological analysis
  • Tube 2 is used for chemical analysis (protein and glucose)
  • Tube 3 is used for white cell count
• Centrifuge the CSF and aspirate the supernatant
• Use the supernatant for:
  • Detection of capsular antigen using latex agglutination.
• Use the deposit for:
  • Preparation of a smear that is stained with Gram to demonstrate gram-negative diplococci (intracellular and extracellular)
  • Culture on chocolate agar or Thayer Martin medium (incubate at 37C for 24 hours in 5-10% CO2 conditions).
  • Identification of colonies based on morphology, gram stain, oxidase test, fermentation of glucose and maltose (with acid only).

Diagnosis of N. Meningitidis Carriers

• Use a nasopharyngeal swab from a nasopharyngeal specimen (West swab), culture on Thayer Martin medium (incubate at 37C for 24 hours in 5-10% CO2 conditions)

Oxidase Test

• The oxidase test is used to identify bacteria that produce the enzyme cytochrome c oxidase
• Cytochrome c oxidase is a key component of the electron transport chain in certain bacteria
• The enzyme enables the bacteria to use oxygen as the terminal electron acceptor (aerobic respiration)
• Oxidase-positive bacteria: Neisseria, Pseudomonas, and Vibrio

N. meningitidis vs. N. gonorrhoeae

• Morphology:
  • N. meningitidis: Capsule
  • N. gonorrhoeae: No capsule
• Chemical Fermentation:
  • N. meningitidis: Glucose and maltose (with acid only)
  • N. gonorrhoeae: Glucose
• Virulence Factors:
  • N. meningitidis: Capsule, pili
  • N. gonorrhoeae: Pili
• Disease:
  • N. meningitidis: Meningitis
  • N. gonorrhoeae: Gonorrhea
• Mode of Transmission:
  • N. meningitidis: Droplet
  • N. gonorrhoeae: Sexually

Moraxella Species

• Moraxella species are aerobic, gram-negative cocci that often appear in pairs or tetrads
• Medically relevant species: M. catarrhalis and M. lacunata
• Moraxella species are opportunistic pathogens

Diagnosis of Moraxella Catarrhalis

• Culture on blood agar or chocolate agar
• Colonies are smooth, grayish, and non-hemolytic

This quiz covers the characteristics and growth requirements of gram-negative cocci, particularly focusing on the Neisseria species. It examines their staining properties, morphology, and significance in infectious diseases. Test your understanding of these important microorganisms and their clinical relevance.