Download 1 - UAB School of Optometry

Pathology
Dr Waites
22 September 2006
Transcriber: Andy/Byron
Page 1 of 7
(50:12)
Neisseria and Chlamydia
1) Neisseria and Chlamydia
2) Neisseria meningitidis
3) N. meningitidis
a) Oxidase positive –this is an enzyme test that is commonly used for gram(-) bacteria more so than gram +
b) Gram-negative diplococci –as seen on slide 3- N. meningitidis are much smaller than a neutrophil and can
be extra cellular or intracellular, they are not obligate intracellular pathogens but they are facultative
intracellular pathogens
c) Capnophilic (5 - 7% CO2) – they like extra carbon dioxide to grow
d) Non-motile
e) Grows on chocolate & sheep blood agar –they are not extremely fastidious (aka fastidious organisms are
bacteria that do not grow easily on media that has not had things added to it aka a “high maintenance
bacteria”)
i) Chocolate agar (named due to its color) is blue that has been heated to lyse blood cells, then the
nutrients and things the bacteria need are accessible to them.
ii) Neisseria gonorrhoeae will not grow on unsupplemented blood agar media
4) The Meningococcal Cell Wall
a) It is typical of other gram neg. bacteria in that it contains LPS as a major component of the cell wall; it has
an outer membrane, and also a capsule.
b) Capsule is important in protection from phagocytosis, it is a virulence factor and is the basis of the
meningococcal vaccine.
5) N. meningitidis Pathogenesis- 3 important ones
a) Polysaccharide capsule-surrounds the LPS layer, important in protection and a virulence factor
b) Lipopolysaccharide (endotoxin)-this is the major virulence factor, responsible for many of the clinical
manifestation that occur in meningococcal diseases
c) IgA protease –major Ig in body secretions on mucosal surfaces to prevent attachment of micro organisms
by binding and preventing activity, if it cannot attach it cannot cause disease.
i) Meningococcus break down the IgA thus allow the bacteria to attach
d) Capsule and IgA protease that help it get into the body but it is the endotoxin the help it be a significant
disease.
6) Many people carry N. meningitidus in their upper respiratory tract (in the nose) so occurrence isn’t something
to be concerned about but what happens is the organism can gain access to the blood stream and ultimately into
the spinal fluid; thus this bacteria is a major cause of bacteria meningitis.
a) Nasopharynx  Blood CSF
b) If it gets into the blood, 50% of the time it will cause meningitis
c) Not normally seen as a cause of respiratory infections the major things is blood stream infections and
meningitis;
7) N. meningitidis Serotypes- reason we see this organism as a cause of meningitis and the way it occurs is there
are multiple serotypes
a) 13 serogroups based on polysaccharide capsule antigens; its only when you get mixtures of the serogroups
together and someone is exposed to organism that they do not have that they are like to get invasive
disease: Not important to know these, just presented
i) A, B and C > 90% of cases globally, and most common
ii) A - epidemics in developing countries
iii) B, C, and Y – sporadic and outbreaks in developed countries
b) This is the reason why you see out breaks of meningitis in people in boarding school, college campuses,
military camps, etc. where a good many people are living closely and sharing respiratory aerosols and they
will encounter an organism that their body has not been exposed
8) Colony Morphology- slide 8
a) On chocolate agar they are fairly undiscript, yellowish-blown shiny colonies, look similar on blood agar
too. They grow fairly quickly (overnight).
Pathology
Dr Waites
22 September 2006
Transcriber: Andy/Byron
Page 2 of 7
(50:12)
Neisseria and Chlamydia
9) Oxidase Positive- Slide 9
a) Performed by taking some of bacterial colonies off of agar onto a swab, then add oxidase reagent and if it
turns purple; this is color change is evidence of positive oxidase test
b) So, a gram negative- biplococcus that is oxidase positive good possibility that it is one of the Neisseria
10) Carbohydrate Metabolism- Neisseria will oxidize carbohydrates - Slide 10
a) This is a good way to tell N. meningitidis from other Neisseria because meningitis will oxidize glucose and
maltose (his hint: think M for maltose/meningitis).
b) Tell this by using a pH indicator (phenol red) and if the bacteria utilize carbohydrate than acid will be
produced as part of metabolism, thus the solution turns from red to yellow; yellow means organism is
producing acid from substrate
11) U.S:
a) Leading cause of bacterial meningitis in older children and young adults
i) Community -sporadic
ii) Institutional- outbreaks
b) Afflicts approx. 2,800 persons per yr. in U.S. that get meningitis doesn’t seem significant but….
c) 10 – 15% mortality rate with people who get the disease, and it progresses very quickly (within 24hrs you
can be dead)
d) 11-19% that survive have permanent “sequelae”: such as motor dysfunction, intellectual problems,
blindness because of damage to brain tissue
e) Invasive disease can be fatal within hours
12) Worldwide:
a) Only form of meningitis that causes epidemics, many of the others are not things that are easily passed
from person to person, but Meningococcus is easily passed
13) N. meningitidis Epidemiology- Slide 12 just shows the # of people in Colorado with this disease and that there
was an epidemic in 1997 in adolescences and young adults
14) N. meningitidis Epidemiology
a) Humans – only reservoir, not something you can get from animals
b) Spread by respiratory droplets or oral secretions
c) Nasopharyngeal colonization ~ 10-15% in the room have this organism in their nose, but maybe only one
or two serotypes
d) If you lived say in a dorm where you shared serotypes through respiratory aerosols, you are at risk for
developing meningitis.
15) N. meningitidis Risk Factors
a) Household contact of primary case or carrier
b) Crowding (boarding schools, military camps)
c) Socioeconomic status, lower has more likelihood, also means possibly living in more crowded unsanitary
conditions
d) Exposure to tobacco smoke has been linked
e) Recent viral upper respiratory infection where epithelium has been damaged thus easier for organism to
invade and get into blood stream then CSF
f) Asplenia- lack of a spleen infectiousness due to importance of Ab production
g) Properdin or terminal complement deficiency – genetic deficiency in complement pathway lead to this
because complement is very important in protecting us from meningococcal disease
i) Many times people are diagnosis with complement deficiency due to two or more meningococcal
infections
16) Meningococcal Disease
a) Meningitis
b) Bacteremia
c) Meningococcemia (sepsis) / septicemia - due to endotoxic effects and disseminated intravascular
coagulation (DIC)
Pathology
Dr Waites
22 September 2006
Transcriber: Andy/Byron
Page 3 of 7
(50:12)
Neisseria and Chlamydia
i) Purpura fulminans
ii) Waterhouse - Friderichsen Syndrome- adrenal hemorrhage
d) Respiratory tract infection –not normally that important
e) Focal infection
f) Chronic meningiococcemia
17) Meningococcal Meningitis - Clinical Symptoms
a) Headache – inflammation and swelling of the brain
b) Stiff neck – because inflammation of the meninges
c) Photophobia – bright light sensitivity
d) Altered mental status – delirium
e) Fever
f) Nausea, vomiting
g) Petechial or purpuric rash
h) Pneumonia
18) Petechiae & Purpura – this is one of the first things examined when someone comes in with symptoms, this is a
result of the endotoxin on the vascular system
a) If you press down on the skin these don’t blanch (go pale) this is part of DIC.
19) Waterhouse–Friderichsen Syndrome –Slide 18 hemorrhage into the adrenal gland
20) Neisseria meningitidis-Slide 19 brain is covered with a purulent exudate, also called empyema (collection of
puss over surface of brain): It’s bad – don’t get it!
21) Meningococcal Meningitis Prognosis
a) Signs associated with fatal outcome:
i) Shock
ii) Purpuric rash
iii) Low or normal WBC – especially important cause you want a vigorous white cell response to infection
but in these fatal cases white cells don’t respond adequately and this is not a good sigh
iv) Age greater or equal to 60 yrs – younger people do better
v) Coma- the disease has already progressed significantly
b) 10% of those who recover
i) Permanent neurologic disability
ii) Hearing loss
iii) Limb loss – due to gangrene because the thrombosis and DIC occurs
22) Prevention of Meningococcal Disease
a) Chemoprophylaxis after exposure
b) Vaccination – should be offered to everyone when entering college especially those living in dorms
i) New conjugate vaccine licensed in 2005 because even though we have a vaccine it is not uniformly
effective.
c) Vaccine Recommended for these groups:
i) U.S. military personnel
ii) Children 11-12 yrs – since it is a polysaccharide vaccine it isn’t a long lasting immunity in younger
children
iii) Persons at risk during outbreak – can go ahead a start to mount an immune response
iv) Travel to high risk area
v) College students
vi) Asplenia
vii) Complement deficiencies
viii) Laboratory workers
23) Vaccine Limitations
a) No protection against Serogroup B (this is not the most common of the serotypes anyways)
i) Polysialic B capsule not immunogenic
Pathology
Dr Waites
22 September 2006
Transcriber: Andy/Byron
Page 4 of 7
(50:12)
Neisseria and Chlamydia
b) Not useful in children < 2 yrs because it is a polysaccharide vaccine
c) New conjugate vaccine may
i) Provide longer immunity due to presence of protein conjugate, previous had to get revaccinated every 5
yrs
ii) Reduce carriage
d) Can take prophylactic antibiotic to meningitis to help prevent getting disease when not enough time is
present for vaccine to mount immune response i.e. someone comes into ER has disease, one can take
preventative antibiotic.
24) SIDE NOTE: Epidemiology of Major STDs in USA
a) Intro to STDs chart shows the # of major STDs diagnosis in US; you see that Chlamydia has over 1 million
cases per year and is more common than Neisseria gonorrhoeae and about the same as human papilloma
virus, herpes. Chlamydia is more common than syphilis, more common that hepatitis B. Trichimonus is a
STD, Chankroud, Lyphagranuloma ingunala being much less common. This is just to put things into
perspective of what you might see.
25) Neisseria gonorrhoeae - This is the other major organism in the Neisseria genus that we need to be familiar
with, exudate looks just like the previous picture of meningococcus from CSF, gram negative biplococci
26) Characteristics
a) Kidney-shaped
b) Nonmotile
c) Gram-negative diplococci
d) Like to grow in CO2
e) Require specialized medium & incubation conditions for growth- this organism is more fastidious and will
not normally grow on blood agar, have to have chocolate agar for it to grow properly (will grow overnight
on chocolate agar)
27) N. Gonorrhoeae Pathogenesis
a) Venereal or vertical transmission- organism not normally carried in respiratory tract it is carried in the
urogenital tract, so sexual contact with mucosal membranes is important in transmission; vertical means it
can be transmitted from mother to offspring during vaginal delivery (ocular tissues are of particular
suseptiable to infection and inflammatory response; know as opthalmian neonatorum)
b) Pili enhance attachment to cells
c) Opacity (opa) proteins in outer membrane (gonococcus being an gram – so will have an outer membrane)
facilitate cell invasion
d) Endotoxin
e) Peptidoglycan - tissue toxin
f) Intracellular location – helps protect it from the host immune system (complement, Ab, etc.)
g) IgA protease
h) Antigenic variation -no permanent immunity following infection; reason for success, as these organisms
reproduce they change their surface Ag and thus keeps our immune system guessing, this keeps us from
getting permanent immunity following infection (as in the case of measles once you get it you are always
immune to it) because it changes its Ag so frequently it doesn’t allow the immune response to cover all the
different strains, so you can get it over and over (this is why there is no vaccine)
i) Penicillin resistance - plasmid & chromosomal
28) N. Gonorrhoeae Detection
a) In a man it is simple it is primary a urethritis, the organism invades the epithelium of the urethra in a male
and the cervix in a female. The distal urethra is normally sterile therefore if you get a purulent discharge
and you see PMNs with diplococci you have made your diagnosis
b) Gram stain of urethral discharge in male
i) Gram-negative diplococci in PMNs
c) Culture
Pathology
Dr Waites
22 September 2006
Transcriber: Andy/Byron
Page 5 of 7
(50:12)
Neisseria and Chlamydia
i) necessary in females women have non-pathogenic Neisseria and other bacteria in the lower urogenital
tract, so just seeing the bacteria will not tell you anything
ii) very susceptible to cold stress & drying (like to be on a warm mucosal surface)
iii) oxidase positive
iv) glucose utilization (unlike the meningococcus, g for gonorrhoeae and g for glucose)
v) Requires CO2 to grow
d) Nucleic Acid Amplification: in recent years these tests have been employed, you can do these tests on
voided urine and don’t have to do a pelvic exam, you can also tell Chlamydia from Gonorrhoeae even
though they have similar features, the Chlamydia is obligate intracellular organism so it can’t be cultured
easily, it is slower to grow and it is very expensive to culture it; this test allowed you to screen large at risk
populations in large quantities with urine only since it is often asymptomatic (REALLY THE IDEAL
TEST); one of the first circumstances where molecular biology type tests have come into use in the
diagnostic and not just the research setting
e) Chocolate agar + antibiotics (Thayer-Martin is the most common example)
i) The antibiotics keep the normal flora (so will contain anti-fungals, drugs to kill gram + etc.); must keep
them warm
29) N. Gonorrhoeae Diseases: this is a penile discharge from the urethra it is analogous in women
a) Cervical/urethral gonorrhoeae
i) 20-30% likelihood of transmission
b) Asymptomatic carriage – women (usually not so in the man)
c) Complications (especially in woman)
i) Arthritis – it can invade the joints
ii) pelvic inflammatory disease (PID) – spread throughout the pelvic cavity, the pus gets into the fallopian
tube in women and can cause scarring and infertility, it also puts you at risk for tubal pregnancies
because the lumen gets narrowed in the fallopian tube and the egg is unable to get into the uterus to
implant so it implants in the fallopian tube and causes an eptopic pregnancy and put the woman’s life in
danger
iii) infertility
iv) proctitis – gonococcal infection of the rectum can occur if you have anal sex and the man has it
v) pharyngitis – gonococcal infection occurring if oral sex occurs and the man has gonorrhoeae, so you get
a sore throat
vi) ophthalmia neonatorum – where the infants eyes are inoculated with gonorrhoeae at birth; for this
reason it is standard practice that if someone comes in without prenatal care and you haven’t done a
culture you give them silver nitrate or erythromycin drops in the eyes of the infant at birth to prevent
blindness if it is there
30) Ophthalmia neonatorum – shows the inflammation you see
a) Neonatal gonococcal or chlamydial ocular infection (Chlamydia can cause the same reaction)
b) Acquired by passage through infected birth canal
31) Neisseria gonorrhoeae Prevention
a) No effective vaccine
b) Use of condoms
c) Education – so people understand the dangers of unprotected sex
d) Silver nitrate or antimicrobial drops in neonate eyes – silver nitrate is no longer used because it caused
inflammation in the ocular tissues and caused a chemical conjunctivitis and antimicrobial agents work just
as well without the side effects
32) Chlamydia trachomatis – causes diseases similar to gonorroheae
33) Chlamydia trachomatis Characteristics
a) Obligate intracellular pathogens – must live in the host cell to survive, you won’t see them in the
environment
b) Lacks peptidoglycan – prevents many antibiotics from being used (e.g. that is where the beta lactams act)
Pathology
Dr Waites
22 September 2006
Transcriber: Andy/Byron
Page 6 of 7
(50:12)
Neisseria and Chlamydia
c) Unique intra-cytoplasmic growth cycle
d) Depend on host for ATP – bacteria before had a sufficiently large genome with ribosomes to make ATP for
metabolic reactions, but Chlamydia are parasites on the host cell that use the hosts energy to drive their
metabolism
e) Growth within cytoplasmic inclusion in the host cell
i) prevents phagolysosome fusion which would cause lysosomal enzymes that would kill them, so what
kills other bacteria inside cells has been circumvented in Chlamydia; this is their main virulence factor
f) Stain with Giemsa (nothing else will, due to lack of peptidoglycan)
g) 15 serovars that are immunologically distinct
34) Chlamydia Life Cycle – the infectious particle of the Chlamydia is known as the elementary body. It
encounters the host epithelium in the urogenital tract or in the respiratory tract (usually in the urogenital tract).
It is taken up into the host cell and under these circumstances it will become metabolically active and it will
change its conformation into the reticulate body. These will replicate in the host cell and it is about a three day
cycle from the time it is taken up by the host cell, converts into reticulate bodies, replicates, and then the
reticulate bodies will undergo a transformation back to elementary bodies. The elementary bodies are the
infectious form while the reticulate bodies are the replication form. Then all the new elementary bodies are
released from the host cell to infect more cells. All of this is taking place inside the epithelial cells of the
human host.
35) Chlamydia trachomatis Pathogenesis
a) Ocular Infections (in addition you can get trachoma which is ocular infections in an adult): PMNs
(inflammatory response) → monocytes→ macrophages → plasma cells → lymphoid follicles → fibrosis,
scarring; this is a more chronic type inflammation that occurs with the ultimate result of scarred tissue
occurring and blindness can occur
b) Genital Infections: organism attached to mucosal epithelium induces inflammation & discharge
c) Not as pyogenic as N. gonorrhoeae; you don’t get such as vigorous pus collection as you do in gonorrhoeae
d) Also some Ag detection tests that are done but they aren’t as good because they don’t amplify the DNA so
they aren’t sensitive
36) Chlamydia trachomatis Detection
a) Cell culture, stain inclusions with monoclonal antibodies that are fluorescently labeled then you look under
a fluorescent microscope to see them
b) Nucleic acid amplification (method of choice)
c) Antigen detection - cheaper than nucleic amplification but less sensitive
37) Ocular Trachoma – this is what you see on the conjunctiva when the Chlamydia are inoculated in the eye;
remember you can see it in the 1. genital tract (a STD), 2. vertical transport to the neonate but it can also cause
a neumonitis because the organisms are transported to the lung, or 3. ocular trachoma where the ocular tissue is
directly inoculated by Chlamydia trachomatis
a) 400 million children & adults worldwide – so very common, you see it in many developing countries where
hygiene is poor
b) C. trachomatis serovars A, B, Ba, C
c) Most common in developing countries
d) Follicular keratoconjunctivitis – this is the outcome, and if it is not properly treated then blindness can
occur (however it can be treated with antibiotics)
38) Neonatal Infections due to C. trachomatis
a) Inoculation at birth from infected mothers
i) Inclusion keratoconjunctivitis
ii) Pneumonitis
39) C. trachomatis Genital Disease in Adults
a) Cervicitis in women
b) Non-gonococcal urethritis in men (gonococcus is not involved)
i) You get many of the same complications as Gonorrohea
Pathology
Dr Waites
22 September 2006
Transcriber: Andy/Byron
Page 7 of 7
(50:12)
Neisseria and Chlamydia
c) One of the most common STDs
d) Complications: infertility, ectopic pregnancy, salpingitis
i) Chlamydia is actually more common than gonorrohea in these cases
e) Many women asymptomatic – so they spread it easily
f) If you suspect a child has been sexually abused, if you can get a positive culture for Chlamydia for the
genital tract of a child it is good evidence sexual abuse has taken place because kids shouldn’t have this
organism. You can also determine rape. Part of the workup for rape is a test for gonorrohea and chlamydia
40) Lymphogranuloma Venereum
a) Caused by C. trachomatis serovars L1,L1,L3
b) Instead of urethritis it goes to the regional lymph nodes and causes inguinal lymphatic involvement with
obstruction
c) Much less common STD than chlamydial urethritis
d) It is mainly getting granulomas in the lymph nodes
41) Prevention of C. trachomatis Infections
a) No effective vaccine
b) No protective immunity following infections (so can get it repeatedly)
c) Improve socioeconomic & hygiene conditions
d) Education
42) Chlamydophila psittaci (disease of psittaci birds)
a) Disease of parrots & parakeets sometimes transmitted to humans
b) Respiratory infection (pneumonitis) of birds that is sometimes transmitted to those with these birds as pets
c) Serologic diagnosis – diagnose it with an Ab titer to the Chlamydia psittaci
d) Transmitted in bird droppings then can be aerosolized and inhaled leading to pneumonia type situations
e) Chlamydophila is the new name for Chlamydia that are not the STDs. It is very similar in terms of its life
cycle except for it doesn’t inhabit the genital tract it inhabits the upper respiratory tract. Many people have
it in their nasopharynx, but it doesn’t often cause disease. It can cause sore throats, sinus infections,
pneumonias.
43) Chlamydophila pneumoniae - New species (1980s)
a) Acute lower respiratory illness, pharyngitis, sinusitis
b) Similar to mycoplasma
c) Frequently asymptomatic
d) Detected by PCR, cell culture, serology but they aren’t very standardized and they just aren’t done often.
(so very hard to diagnose)
e) Diagnostic testing not widely available
f) Relation to other chronic inflammatory conditions such as atherosclerosis and coronary artery disease? You
have probably heard about this because it can be carried for a long time without any sign, and in the 1990s
studies found the Ag of these organisms in atherosclerotic plaques in coronary arteries. The hypothesis is
you get colonized with the organisms early in life, and then it spreads out and settles in all tissues. The
ones in the BV stimulate atherosclerosis. The bacteria showed up in people with coronary artery disease
more often than those without heart disease, and it showed elevated Ab response to it. The hypothesis was
made that these organisms in BV stimulate an inflammatory response that will hasten the progression of
atherosclerotic disease. So you might treat heart disease with antibiotics. The studies right now are not
conclusive.