Mycoplasma, Spirochetes, Chlamydia, and Rickettsia I Flashcards by Joel Glotfelty

Cannot synthesize ATP without host cell instead has a transport system to import into cell

-Obligate intracellular parasites

Chlamydia

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Has a small genome, in fact Mycoplasma is the only other bacteria with smaller genome; however, mycoplasma can synthesize most of their proteins and RNA

Chlamydia

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Three species in genus Chlamydia, C. trachomatis, C. pneumoniae, and C. psittaci, are associated with

Human disease

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The extracellular form of chalmydia is

Spore-like

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Where do all chalmydia replicate?

Cytoplasm of their host

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Serotypes of this one organism cause a wide variety of diseases such as:
• ocular trachoma
• inclusion conjunctivitis-adult/perinatal
• infant pneumonia
• genital tract infections
• lymphogranuloma venereum

Chlamydia trachomatis

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Chlamydia trachomatis is the most common cause of preventable

Blindness

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Natural infection with C. trachomatisappears to confer very little protection against

Reinfection

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Chronic conjunctivitis, progresses into scarring and blindness

-in endemic areas, usually occurs early in life and persists for several years

Ocular Trachoma

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An acute infection of the conjunctiva

Inclusion conjunctivitis

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50% of adults with inclusion conjunctivitis have concurrent

Genital tract infections

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In infants, usually acquired during passage through infected birth canal

Inclusion conjunctivitis from chlamydia

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In the US, all newborns are given prophylactic treatment with

Erythromycin

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10-20% infants born to mothers with genital tract infections develop

Infant pneumonia

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50% of infants with pneumonia have a history of

Conjunctivitis

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The majority of genital chlamydial infections in both males and females are

Asymptomatic

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In woman, infection can lead to cervicitis, urethritis, pelvic inflammatory disease; the latter may lead to infertility or ectopic pregnancy

Chlamydia

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In woman, infection increases risk of HIV infection up to 5-fold

Chlamydia

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In men, chlamydia infection can lead to nongonococcal

Urethritis, epididymitis, or proctitis

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PCR-based tests from vaginal swab (women) or urine (men) are used to test for

Chlamydia

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We can test for cervical cancer and Chlamydia with a single ThinPrep

Endocervical specimen

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Of the three species of Chlamydia, the most common cause of human infection is

Chlamydia pneumoniae (TWAR)

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The serovar TWAR is only recognized serovar of

Chlamydia pneumoniae

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Chlamydia pneumoniae is most common in children ages

5-14

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Mostly associated with mild upper respiratory tract infections but can also cause pneumonia or bronchitis

Chlamydia pneumoniae

Cause psittacosis (parrots, parakeets, cockatoos, etc.) or ornithosis (domestic & free living birds); zoonosis contracted through inhalation of respiratory secretions or dust from droppings of infected animals, or through handling of infected tissues

Chlamydia psittaci

Category B level bio-terrorism agent because it can be aerosolized

Chlamydia psittaci

Occurs in a wide range of avian species, but may infect other animals as well

Chlamydia psittaci

Human to human transmission of chlamydia psittaci is

Rare

Produces spectrum of clinical manifestations ranging from severe pneumonia to mild and undetectable infection--hard to diagnose

Chlamydia psittaci

The most common symptoms of chlamydia psittaci are

Fever, headache, and sore throat -cough not present initially but is in late disease

What are the general features of spirochetes?

Gram negative with coiled cell wall, motile, endoflagella

Depending on the organism, culture is either very difficult or has not yet been demonstrated for

Spirochetes

What are the three genera of spirochetes that cause disease in humans and animals?

Borrelia, Leptospira, and Treponema

Borrelia burgdorferi is commonly known as the cause of

Lyme disease

Borrelia recurrentis is commonly known as

Relapsing fever

Treponema palidum is commonly known as

Syphilis

Difficult to culture in the laboratory -Has very limited biosynthetic capacity and depends on host cell to fulfill nutritional requirements

B. burgdorferi

Transmitted by the bite of the small deer tick Ixodes

Borrelia burgdorferi (Lyme disease)

A living animal or plant on or in which a parasite lives

Host

An organism in which a parasite that is pathogenic for some other species lives and multiplies without damaging its host

Reservoir

An organism (as an insect) that transmits a pathogen from one organism or source to another

Vector

The most common vector borne illness in the US and Europe

Lyme disease

Is also a vector for other pathogens; therefore, coinfection with B. burgdorferi and another organism is not uncommon (sometimes as high as 40%)

Ixodes

~80% of coinfections in the East Coast involve Lyme disease and

Babesiosis

Transmission of lyme disease requires tick attachment for a minimum of

24 hours

Can be used prophylactically to treat lyme disease from a tick bite

Chemoprophylaxis with Doxycycline

Surface exposed lipoproteins (OspA-F) are the only known virulence factors of

B. burgdorferi

A lipoprotein that mediates spirochete attachment to the tick gut, and to each other

OspA

Infection is highly variable among patients, can be brief or chronic, affect one or multiple systems

Lyme disease

Early infection stage 1 of lyme disease is a

Localized infection

This stage is characterized by a slowly expanding erythema migrans within

7-10 days after tick bite

Hot to the touch and causes a burning sensation; sometimes it itches and is painful

Erythema migrans

Early infection stage 2 of lyme disease is

Disseminated infection

Days to weeks after an infected tick bite, we see

Flu-like symptoms and multiple skin lesions

Weeks to months after an infected tick bite, we see

Musculosceletal pain and potentially Bell's palsy

Late infection, i.e. stage 3, occurs months to years after the tick bite and is classified as

Persistent infection

Presents with chronic nervous system and joint involvement; Lyme arthritis in primarily large joints, especially the knee

Late infection (stage 3)

What are the three most common clinical manifestations of confirmed lyme disease?

Bells palsy, arthritis, and Erythema migrans

Presence of EM, clinical presentation and exposure in an endemic area often prompts antibiotic treatment without

Serologic confirmation

In the absence of EM, the CDC recommends a two-test serological approach. What are the steps

1.) EIA first If positive or ambiguous, 2.) Confirm with western blot

What is the criteria for lyme disease in a western blot using 1. ) IgG 2. ) IgM

1. ) 5 out of 10 must react | 2. ) 2 out of 3 must react

How many mycoplasma organisms are definitively associated with human disease?

Which mycoplasma causes upper respiratory infection, bronchitis, and pneumonia

Mycoplasma pneumoniae

Which mycoplasma cause 1. ) In men: nongonococcal urethritis 2. ) In women: vaginosus, cervicitis, and PID

Ureaplasma urealyticum, mycoplasma hominis, and mycoplasma genitalium

Smallest free-living organism (size and genome)that can also be cultured on laboratory media

Mycoplasma

Mycoplasma are highly polymorphic in shape due to

Lack of a rigid cell wall (No peptidoglycan)

Have no rigid cell wall due to no peptidoglycan. But instead have a three-layered cell membrane

Mycoplasma

Completely resistant to penicillin and other antibiotics that attack cell wall

Mycoplasma

Mycoplasma generally stains

Poorly or not at all

Because they lack a cell wall, the major antigenic determinants of mycoplasmas are

Membrane glycolipids and proteins

Therefore, antibodies to mycoplasmas cross-react with

Human tissues

Colonies of the most clinically important mycoplasma species, M. pneumoniae,classically described as having a

Dense mulberry shape -can also be spherical

Colonies from the other three species have a characteristic

Fried egg appearance

What do mycobacteria require in a media in order to grow?

A cholesterol source

Have sterol-containing membranes

Mycobacteria

Transmitted from person-to-person by coughing, respiratory secretions

Mycoplasma pneumoniae and atypical (or walking) pneumonia

A prominent causative agent of pneumonia; especially in closed populations (military recruit camps, boarding schools, colleges, summer camps)

Mycoplasma pneumoniae

Prospective studies suggest that M. pneumoniae accounts for 15% -20% of adult community-acquired

Lower respiratory infections

This respiratory pathogenicity is due to the high affinity of M. pneumoniae for

Respiratory epithelial cells

Attachment occurs at the base of the cilia and is mediated by a terminal organelle composed of adhesins and auxiliary proteins at one end of

M. pneumoniae

What part of epithelial cells acts as a receptor for M. pneumoniae? -on cell surface

A glycoprotein

Adherence-deficient mutants are

Avirulent

Adherence-deficient mutants are avirulent; adhesins(P1, P30, P65 and P116) and their auxiliary proteins (HMW1, 2, 3) are the primary

Pathogenic elements

Attachment leads to loss of ciliary action, followed by loss of cilia, then sloughing of the cell into the lumen; this action thought to underlie the hallmark

Cough

A clinical characteristic of atypical pneumonia is an incubation period of 2-3 weeks. Vs. the 1-3 days seen for

Viral respiratory infections

Typically a gradual(occurring over several days) onset offever, malaise, headache, cough (slow onset and cough are clinical hallmarks)

Atypical pneumonia

We primarily see upper respiratory infections with ages

3 or less

Between ages 5 and 20, we see

Bronchitis and pneumonia

Mycoplasma infection leads to the formation of cold agglutinins. These are

IgM anti-bodies

Patients with sickle-cell disease or related diseases are more susceptible to higher disease severity from

M. pneumoniae

Culturing M. pneumoniae is not practical because it can take up to

2 weeks

An obsolete test for M. pneumonia; not specific or sensitive enough for diagnostic purposes

Cold agglutination

The most specific and rapid tests for M. pneumonia

PCR-based tests

Outpatients presenting with pneumonia are often treated with standard therapy for community acquired pneumonia (CAP), which may not be effective against

M. pneumonia

This is because M. pneumonia does not respond to

B-lactam antibiotics