Chapter 154 - Gram Negative Coccal and Bacillary Infections Flashcards
Mortality rates for meningococcal infection in the United States
10% to 15%
Gold standard for diagnosis of meningococcal infection
Culture isolation of N. Meningitidis from blood, CSF, other bodily fluids, or skin biopsy tissues
In the US, vaccination with a capsular polysaccharide conjugate vaccine against serogroups __ is recommended for all patients at ___ with a booster at ___
A, C, W135, Y
11 or 12 years old
16 years old
N. Meningitidis is almost always encapsulated hence allowing differentiation into serogroups based on ___
Capsular polysaccharides
Capsules decrease the visibility of N. Meningitidis via molecular mimicry, best illustrated by serogroup ___
B
Poor prognostic marker for meningococcal infection
High serum lipooligosaccharide (LOS)
Facilitates adherence to endothelial cells, mediate vascular damage, and facilitate breach of blood brain barrier
Type IV pili
Nasopharyngeal carrier rates for
Infants and young children, adolescents, and in young adults.
0.5 to 1%
5%
20 to 40%
In meningitidis, __ have higher risk of infection; while ___ have higher mortality
Males
Females
Matching type
- Meningitis and meningococcemia in infants younger than 6 mos old
- 25% of meningococcal pneumonia in older adults
- Most devastating outbreaks in subSaharan Africa
- Infections with high mortality in subSaharan Africa
- Most recent serogroup to emerge as cause of disease in subSaharan Africa
- 30-40% in US, 80% in Europe
- 30% in US and Europe
Y Y A W135 X B C
Hallmark of acute meningococcemia
Acute petechial rash (60%) in extremities
Petechia were more common in infants than in children or adults.
True or False
False, children 1 to 18 years old (74%) than infants (48%) or adults (45%)
Presence of petechia predicts risk of mortality, but rapid increase in number and size does not correlate with fulminant disease progression.
True or False
False, do not predict risk of mortality but predicts risk of fulminant disease progression
Life threatening condition characterized by adrenal hemorrhage, ensuing adrenal crisis, often accompanied by purpura fulminans.
Waterhouse-Friderichsen syndrome
Most common sequela of meningitis
Sensorineural hearing loss or deafness
Triggers production of proinflammatory cytokines of the innate immune system including IL6, IL8, TNF alpha which contributed to endothelial damage
Lipooligosaccharide (LOS)
Single greatest risk factor for disseminated meningococcal disease
Lack of bactericidal antibodies
- Anatomical or functional asplenia
- HIV infection
- Defects in terminal or alternative complement pathway
CSF findings in meningococcal meningococcal meningitis
CSF leukocytes exceed 100 x 106/L
Elevated protein
Decreased glucose
Direct cause of death from acute meningococcal infection (2)
Shock, multiple organ failure
Single most important factor in treatment of acute meningococcal infection
Early initiation of antibiotics
No more than 30 mins from initiation of antibiotics
Presumptive treatment for meningococcal meningitis
3rd gen cephalosporin
Ceftriaxone or cefotaxime for 7 days
Not beneficial in meningococal meningitis although useful in pneumococcal diseases
Dexamethasone
Droplet precaution should be maintained from presumptive diagnosis until at least __ hours after initiation of effective antibiotic regimen
24
Close contacts are defined as those who have prolonged contact (> ___ hours) within close proximity (< ___ feet) of infected patient or those who had direct exposure to oral secretions from ___ days before the onset of symptoms until ___ hours ff initiation of effective antibiotics
8 hours
3 feet
7 days
24 hours
Single most impt factor in treatment of acute meningococcal infection is
Early initiation of antibiotics
N. Meningitidis can be diff from N. Gonorrhoeae by its maltose fermenting abilities.
True or False
True
On blood agar, N. Meningitis is light gray round, glistening and ___
Nonhemolytic
Nonpathogenic N. Meningitis is almost always nonencapsulated.
True or False
True
Vital for survival as it inhibits antibody and complement mediated killing and phagocytosis of N. Meningitidis
Capsule
Down regulator of alternative complement pathway
Factor H binding protein
Exclusive natural hosts for N. Meningitidis
Humans
Characterized by retiform purpura and necrosis of skin which may extend to subQ and occasionally muscle and bone
Purpura fulminans
In some cases, chronic meningococcemia can evolve into (3)
Acute meningococcemia
Meningitis
Carditis
MOT of N. Meningitidis
Droplet or direct contact (arises wirhin 2 weeks)
In acute meningococcemia, blood cultures may be positive in 40-80% but declines rapidly with initiation of antibiotics.
True or False
True
In contrast to blood and CSF, meningococci can still be cultured from skin lesions up to ___ hours after antibiotic administration
13
Highest sensitivity for culture
Blood specimen
Highest sensitivity for culture and Gram staining
CSF
PCR is most useful in
Negative cultures
And
Cheonic meningococcemia
Latex agglutination test kit is not routinely performed as it cannot detect serogroup
B
Chemoprophylaxis administered more than __ days is not recommended
14 days
Chemoprophylaxis for meningococcemia
Rifampin 4 doses in 2 days (children &adults)
Ciprofloxacin (adults)
Ceftriaxone single dose IM
(Pregnant)
Polysaccharide conjucate vaccine with DIphtheria toxoid against ACW135Y
Menactra
Menveo
Recombinant vaccines against serogroup B
Bexsero
Trumenba
Pseudomonas aeruginosa blue green nonfluorescent color specific is conferred by ___
Pyocyanin
Malignant otitis externa is invasive with a mortaity rate of
20%
Mortality for ecthyma gangrenosum is ___
30-70%
In MacConkey agar, P. Aeruginosa appear ___ due to ____
White, non lactose fermenter
P. Aeruginosa is obligately aerobic and grows best at
42 C
Green yellow pigment of P. Aeruginosa that fluoresces under a Wood lamp
Pyoverdin
Matching type
- TNF alpha production
- Binds adenosine diphosphate-ribosyltransferase
- Binds adenylate cyclase
- Damages cell membranes
A. Exo S
B. Exo T
C. Exo U
D. Exo Y
A
B
D
C
Higher levels of serum exotoxin A antibodies results in more severe P. Aeruginosa septicemia.
True or False
False, less severe
TLR 4 agonist and septic shocj mediator common to Gram (-) bacteria
Lipopolysaccharide
Confers resistance to antibiotics
Biofilm formation
P. Aeruginosa is number ___ for patients with cystic fibrosis; ___ for nosocomal pneumonia; ___ for catheterized patients who had UTI
1st
2nd
3rd
Accumulation of ___ results to chloronychia
Pyocyanin
Triad of Green nail syndrome
Dyspigmentation
Onycholysis
Paronychia
External otitis is common in children ages
5-14 years old
Classic finding of malignant otitis externa
Presence of granulation tissue in floor of external auditory canal
Ecthyma gangrenosum is commonly seen in
Anogenita region (57%)»_space; extremities (30%)
Most frequent serotype isolated from P. Aeruginosa is
O11
Bacteremia with P. Aeruginosa is common in patients with CD4 count less than
50 cells/ul
Used to monitor disease activity in external otitis
ESR and CRP
Treatment for green nail syndrome
Topical antimicrobials 2% NaOCl Tobramycin Gentamicin Bacitracin Polymyxin B Ciprofloxacin \+ avoidance of water submersion
Treatment for external otitis
Oral ciprofloxacin for 7-10 days
Malignant otitis externa warrants Tx with
Ciprofloxacin for 6-8 weeks
Alt: anti pseudomonas penicillin for 6-10 weeks
+ mastoidectomy
In those with neutropenia, burn wounds, ecthyma gangrenosum, or signs of spesis, management is
Antipseudomonal B lactam + aminoglycoside
Alternative drug for multidrug resistant strains but with very high rates of nephrotoxicity
Colistin
Alternative options for multidrug resistant infection
Ceftazidime-Avibactam
Ceftolozane-Tazobactam
Colistin
Homemade ear drops comprised of
1:15 acetic acid + isopropyl alcohol