Gram negative cocci Flashcards
Gram negative cocci includes?
Gram negative cocci includes
- Neisseria
- Acinetobacter
- Moraxella
Neisseria
Neisseria
- Gram negative diplococci (pairs) *
- Oxidase positive, catalase positive *
- Some species are normal flora on mucosal surfaces (oropharynx, genital tract)
- Species of medical imp. (never normal flora)
- Neisseria meningitidis
- Neisseria gonorrhoeae
Neisseria meningitidis
Neisseria meningitidis
- Encapsulated gram negative diplococcus *
- Oxidase + , catalase + *
- Breaks down maltose & glucose (MeningoCoccos) *
- Reservoir:
- Human nasopharynx (5-10% healthy carriers)
- Transmission: INHALATION of respiratory droplets
-
Common cause of meningitis
- Most common cause in age group 2 – 18 yrs *
- Six serogroups are associated with meningitis – A, B, C, X, Y, W135
Case presentation of Neisseria
(Gram negative cocci)
Case presentation of Neisseria
- An 18-year-old (or peopel around that age)
- high fever
- vomiting, and joint and muscle pain.
- nuchal rigidity,
- petechial rash on the trunk and lower extremeties
- photophobia.
- Lumbar puncture:
- Cloudy CSF
- Gram stain – Gram-negative cocci in pairs
- elevated protein, decreased glucose levels
- Elevated WBC count (mostly neutrophils)
Petechiae/Petechial rash
Petechiae/Petechial rash
- PETECHIAE, PURPURA, AND ECCHYMOSES
- Three terms that refer to bleeding that occurs in the skin are petechiae, purpura, and ecchymoses.
- Generally, the term “petechiae” refers to smaller lesions.
- “Purpura” and “ecchymoses” are terms that refer to larger lesions. In certain situations purpura may be palpable. In all situations, petechiae, ecchymoses, and purpura do not blanch when pressed.
found in Gram negative cocci conditions like neisseria meningitidis
Meningococcus - Virulence factors * * and risk factors
(Gram negative cocci)
Meningococcus - Virulence factors * *
-
Polysaccharide capsule_ _
- Antiphagocytic, antigenic
- 6 common serogroups (A, B, C ,X ,Y , W135 – B & C in USA)
- Detected in CSF specimens
- Vaccine is derived from capsule
-
IgA protease
- Promotes colonization of oropharynx
-
Endotoxin
- **Lipooligosaccharide (LOP) **
- Fever , Endotoxic shock (septic shock)
- Pili & OMP - colonization
- Risk factors: complement deficiency (C5-C8) predisposes to severe infection, septicemia
Meningococcus – Clinical disease
(Gram negative cocci)
Meningococcus – Clinical disease
- Predisposing factors:
- Recent antecedent viral resp. tract infection
- Smoking (active/passive)
- Risk factors for severe disease:
- _Deficiency in complement components (C5-C8)*_
-
Age groups affected*
- In USA – infants less than 1 yr (highest incidence)
- Adolescents/young adults
- Outbreaks in institutions, schools, military barracks, dormitories
Meningococcus - Where does it start? what is it’s progression
(Gram negative cocci)
Meningococcus- where does it start
Colonize nasopharynx → upper respiratory tract → disseminate in blood
- **Meningitis **
- Septicemia (meningococcemia)
Meningococcus clinical presentation and prognosis
(Gram negative cocci)
Meningococcus clinical presentation and prognosis
-
Meningitis
- High fever (rapid onset)
- Nuchal rigidity (stiff neck)
- Photophobia (sensitivity to light), confusion, headache, vomitting
- Petechia (purpural rash) *
- **Rapidly fatal **
- Even if treated early 5-10% patients die within 24-48 hours (WHO)
Pathogens of meningitis for neonates, infants/children, adults
(Gram negative cocci)
Pathogens of meningitis for neonates, infants/children, adults
- _Meningitis in Neonates – _
- Group B streptococci,
- Escherichia coli,
- L monocytogenes
-
Meningitis in Infants and children –
- H influenzae (48%),
- S pneumoniae (13%), and
- N meningitidis
-
Meningitis in Adults –
- S pneumoniae, (30-50%),
- _H influenzae (1-3%), _
- N meningitidis (10-35%),
- gram-negative bacilli (1-10%),
- staphylococci (5-15%),
- streptococci (5%), and
- Listeria species (5%)
N. meningitidis sillly!
Gram negative cocci
Meningococcemia
(Gram negative cocci)
Meningococcemia
- Meningococcal bloodstream infection
- 30% patients with meningococcal meningitis will develop meningococcemia
- What happens ?
- Endothelial injury
- Thrombosis
- Disseminated intravascular coagulation
- _Petechiae (small hemorrhages under the skin)*_
- Septic shock
Waterhouse-Friderichsen syndrome *
(Gram negative cocci)
Waterhouse-Friderichsen syndrome *
- Bilateral adrenal hemorrhage & acute adrenal gland insufficiency *
- Ecchymoses (large purple skin haemorrhages)
- DIC (disseminated intravascular coagulation)
- Hypotension & Shock
- Uncommon condition but fatal
notes:
Waterhouse-Friderichsen syndrome is failure of the adrenal gland due to bleeding into the gland.
Causes
This condition is caused by severe infection with meningococcus bacteria or other severe infection from bacteria, such as:
- Group B streptococcus
- Pseudomonas aeruginosa
- S. pneumoniae
- Staphylococcus aureus
Rarely, Waterhouse-Friderichsen syndrome can be caused by the use of medications that promote blood clotting.
Possible Complications include:
- Acute adrenal gland insufficiency
- Shock
- It is deadly if not treated right away.
Shorty got that younge acne?
(Gram negative cocci)
ECCHYMOSES! found in patients with meningococcemia!
Note:
PETECHIAE, PURPURA, AND ECCHYMOSES ARE:
- Three terms that refer to bleeding that occurs in the skin are petechiae, purpura, and ecchymoses.
- Generally, the term “petechiae” refers to smaller lesions.
- “Purpura” and “ecchymoses” are terms that refer to larger lesions. In certain situations purpura may be palpable. In all situations, petechiae, ecchymoses, and purpura do not blanch when pressed.
N. meningitidis – Diagnosis
(Gram negative cocci)
N. meningitidis – Diagnosis
Lab diagnosis of meningitis
- Gram stain CSF *
- Numerous PMNs (Polymorphonuclear leukocytes) & GN diplococci *
- rapid test
- Culture
- Blood agar with 5-10% CO2 (capnophilic) *
- Additional tests
- Sugar utilization: Maltose & Glucose (MeninGococcus) *
- increased protein, Decreased sugar *
- CSF Bacterial Antigen detection *
- Detects capsular antigen, rapid test
- Lab diagnosis of meningococcemia
- Culture blood
