Mod 7

• Neisseriaceae


  Obligate aerobes, non-motile, and non-hemolytic<|>Fastidious, capnophilic, and grow optimally in a moist temperature<|>Most species are carbohydrate fermenters<|>Grow best in media with blood and cholesterol<|>Have non-pigmented colonies except N. flava, N. flavescens, and N. subflava<|>Sensitive to heat and drying, thus requiring a direct inoculation of specimens at the bedside<|>Their natural habitats are the mucous membranes of the respiratory tract and urogenital tracts<|>Oxidase-positive, gram negative diplococci or rod-shaped that do not elongate when exposed to subinhibitory concentrations of penicillin

  
• Neisseria gonorrhoeae


  • Also known as gonococci, agent of gonorrhea
  • Not part of the human microbiota
  • Humans are the only known host
  • Found in the urogenital tract, anorectal area, oropharynx, and conjunctiva
• Mode of transmission of Neisseria gonorrhoeae

  1. Sexually (leading cause of STDs)

  2. Infected mother to a newborn during birth
• Virulence Factors of Neisseria gonorrhoeae

  • Common pili – Principal virulence factor
  • Receptors for transferrin
  • Capsule
  • IgA cellular membrane proteins (Por B)
  • Lipopolysaccharide (LOS) endotoxin
• Colonial types of Neisseria gonorrhoeae

  T1 and T2 are virulent with pili (urethra/cervix)<|>T3 to T5 are avirulent without pili
• Pathogenesis and Spectrum of Disease of Neisseria gonorrhoeae

  An acute pyogenic infection of non-ciliated, columnar, and transitional epithelium<|>Causes urethritis (males) and cervicitis (females)<|>Untreated gonococcal cervicitis may cause sterility and perihepatitis (Fitz-Hugh-Curtis syndrome)<|>Can cause pharyngitis, purulent arthritis, anorectal infections, and conjunctivitis (opthalmia neonatorum)
• Signs and symptoms of GONORRHEA IN MEN

  • Urethritis with burning upon urination
  • Serous discharge that becomes more profuse, purulent, and at times, tinged with blood
  • Acute epididymitis
  • Urethral strictures with decreased and abnormal urine stream
  • Rectal infection with pain, pruritus, discharge, or tenesmus
• Signs and symptoms of GONORRHEA IN WOMEN

  • Vaginal discharge (most common presenting symptom) that is thin, purulent, and mildly odorous
  • Dysuria
  • Intermenstrual bleeding
  • Dyspareunia (painful intercourse)
  • Mild lower abdominal pain
• Diagnosis of Gonorrhea


  In males, a positive smear + symptoms + history makes the diagnosis<|>In females, a positive smear is less significant because of the normal flora; culture specimen from cervix

  
• Extragenital Infections of Neisseria gonorrhoeae


  • Opthalmia neonatorum - conjunctivitis that can cause blindness with eye pain, redness, purulent discharge
  • Can disseminate into blood (DIC), heart (endocarditis), and joints (arthritis)
• Neisseria meningitidis


  Causative agent of meningococcemia or spotted fever<|>Leading cause of fatal bacterial meningitis<|>Found in the nasopharynx and oropharynx (asymptomatic human carriage in the URT common)<|>Commensal of the upper respiratory tract of the carriers<|>Glucose and maltose fermenter<|>Requires iron for growth<|>β - lactamase test: positive
• Microscopy Morphology and Cultural Characteristics of Neisseria meningitidis

  • Encapsulated strains can have a halo around the organism
  • Encapsulated strains are mucoid
  • BAP: bluish gray colonies
  • CAP: small, tan, and mucoid colonies

  
• Serogroups of Neisseria meningitidis

  • A, C, Y, and W-135
• Virulence factors of Neisseria meningitidis

  • Pili
  • Polysaccharide capsules
  • IgA Protease
  • Cellular membrane proteins (Por A and Por B)
  • LOS endotoxin
• Meningococcemia


  Presence of N. meningitidis in the blood<|>Can occur in an acute or chronic form<|>Can occur with or without meningitis<|>Person-to-person spread through oral secretions and respiratory droplets<|>Signs and symptoms include frontal headache, stiff neck, and fever (epidemic meningitis in adults)<|>Petechial skin lesions may develop during bacteremic spread due to the release of endotoxin after bacterial cell lysis<|>The LOS endotoxin complex produces hemorrhage in the adrenals known as the Waterhouse-Friderichsen syndrome
• Treatment of meningococcal meningitis

  Penicillin is the drug of choice<|>CDC 2015: Single-dose Intramuscular (IM) injection of 250 mg of ceftriaxone taken along with a 1-g oral dose of azithromycin
• Antimicrobial Susceptibility Testing


  For N. gonorrhoeae: use of agar dilution for minimal inhibitory concentration (MIC) measurements and GC agar containing 1% growth supplement<|>For N. meningitidis: performed by disk diffusion on Mueller-Hinton agar or using cation-adjusted Mueller-Hinton broth in microdilution

  
• All testing should occur within a biologic safety cabinet to minimize laboratory-acquired infections
• Nonpathogenic Neisseria (Saprophytic)


  • Neisseria cineria
  • Neisseria flavescens
  • Neisseria lactamica
  • Neisseria mucosa
  • Neisseria sicca
  • Neisseria elongata
  • Neisseria weaveri
• Neisseria cineria


  Colony morphology on CAP is similar to the T3 colonies of Neisseria gonorrheae<|>Colistin susceptibility test differentiates Neisseria cineria from Neisseria gonorrheae<|>Biochemical resemblance with N. gonorrheae<|>N. cinerea grows on MH, N. gonorrheae doesn't<|>N. cinerea doesn't grow in Thayer Martin, N. gonorrhoeae does

  
• Neisseria flavescens


  Assacharolytic, yellow-pigmented Neisseria species<|>It has the ability to grow on BAP and CAP at 22°C

  
• Neisseria elongata


  Assacharolytic<|>"Rod-shaped" Gram negative coccus<|>Weakly positive or negative catalase test

  
• Neisseria weaveri


  "Rod-shaped" Gram negative coccus<|>(+) catalase test<|>Does not produce acid from any of the carbohydrates that are used to identify the Neisseria species

  
• Neisseria lactamica


  Isolated from meningococcal carrier surveys, commonly from children who are two years of age and rarely from adults<|>Lactose Fermenter<|>(+) ONPG (o-Nitrophenyl-b-D-Galactopyranoside) test distinguishes lactose fermenters from non–lactose fermenters and determines the ability of an organism to produce b-galactosidase
• Neisseria mucosa


  Usually isolated from the nasopharynx of children or young adults<|>Grows in a nutrient agar incubated at 25°C<|>Culture: colonies appear large and very mucoid

  
• Neisseria sicca


  Grows in nutrient agar incubated at 25°C<|>Culture: colonies appear large and very mucoid<|>Fructose and Sucrose fermenter

  
• Lab Diagnosis for Neisseria

  • Gram Stain
  • Culture (for confirmation in N. gonorrhoeae)
  • Biochemical testing
  • Immunoserologic testing
  • Molecular testing
  • Antimicrobial Susceptibility Testing
• Specimens for Neisseria

  • For N. gonorrhoeae: Pus secretions from the urethra, cervix, prostate, rectal mucosa, throat, and joint fluid
  • For N. meningitidis: CSF, blood, nasopharyngeal swabs, and petechial skin lesions

  
• Specimen Collection and Handling

  Swabs should be placed in a transport system (Amies medium with charcoal) and plated within six hours<|>Cotton swabs should not be used due to the presence of fatty acids in the cotton fibers<|>N. gonorrhoeae will not be recovered from routine blood cultures because of sodium polyanethole sulfonate (SPS) inhibition
• Gram Stain of Neisseria gonorrhoeae

  Intracellular Gram- diplococci, coffee or kidney bean-shaped is DIAGNOSTIC
• Specimens


  • Pus secretions from the urethra, cervix, prostate, rectal mucosa, throat, and joint fluid
  • CSF, blood, nasopharyngeal swabs, and petechial skin lesions
• Specimen collection and handling

  • It is the most important factor in the laboratory diagnosis of N. gonorrhoeae
  • Swabs should be placed in a transport system (Amies medium with charcoal) and plated within six hours
  • Cotton swabs should not be used due to the presence of fatty acids in the cotton fibers
  • N. gonorrhoeae will not be recovered from routine blood cultures because of sodium polyanethole sulfonate (SPS) inhibition

  
• Gram stain of N. gonorrhoeae

  Intracellular Gram- diplococci, coffee or kidney bean-shaped is DIAGNOSTIC<|>Smears should be prepared from urogenital specimens not from pharyngeal specimens because commensal Neisseria species can be present

  
• Gram stain of N. meningitidis

  Highest yield of positive CSF Gram stain is obtained when specimens are concentrated<|>Gram negative intracellular and extracellular diplococci
• Culture conditions


  N. gonorrhoeae and N. meningitidis require immediate incubation after plating<|>35-37°C for 72 hours in increased CO2 (e.g. candle jar (3% CO2) and JEMBEC system)
• If incubating using a candle jar, only white, unscented candles should be used, because other types may be toxic to N. gonorrhoeae and N. meningitidis
• JEMBEC transport system


  JEMBEC plate, a small white pill, and a plastic bag. When activated, the pill creates a 10% carbon dioxide atmosphere that this organism needs for growth
• Direct inoculation at the bedside is optimal for Neisseria gonorrhoeae
• Nasopharyngeal swabs for Neisseria meningitidis


  Should be plated immediately in JEMBEC system<|>Should be submitted on swabs that are placed in charcoal transport media
• Neisseria meningitidis is sensitive to SPS, so the content in the blood culture broths should not exceed 0.025% and addition of 1% gelatin to counteract