Bacteria (Part IV) Flashcards
What are the gram negative pathologic bacteria-enteric bacteria- that cause respiratory infections? (3)
Bordetella pertussis, Legionella pneumophilia, Haemophilius influenzae
What are the general characteristics of Legionella pneumophilia (gram stain, shape, a(n)erobic, intra or extracellular?
gram negative rod, aerobic, facultative intracellular organism (survives in macrophages)
How does legionella pneumophilia cause infection?
it is aerosolized: found in water systems: cooling towers, condensers, showers, tubs
Where can legionella pneumophilia live?
inside free living amoebas and in biofilms
What 2 specific diseases can Legionella pneumophilia cause?
Pontiac fever and Legionnaires’ disease
how does Pontiac fever present?
self-limited febrile illness (2-5 days): fever, chills, myalgia, malaise, headache
how does Legionnaires’ disease present?
it is more severe: multilobular pneumonia with abscess; fever, chills, cough, can lead to multiorgan dysfunction and death
what are the general characteristics of Haemophilus influenza (gram stain, shape)?
pleomorphic gram negative rod or coccobacillus
what do all haemophilus species require for growth? And where are these found
hemin and NAD (X and V factors); both are found in blood
where must Haemophilus influenza grow?
chocolate agar- it cannot grow on routine blood agar
what does the encapsulated strain of Haemophilus influenza allow?
it is much more virulent and allows blood stream invasion
what is the most important and most virulent encapsulated strain of haemophilus influenza?
Haemophilus influenza type B (Hib)
what is haemophilus influenza type B (Hib) well known for?
early childhood meningitis
when is the Hib vaccination series given?
during the first 1 1/2 years of life
Besides early childhood meningitis, what else does encapsulated Haemophilus influenza type B cause?
acute epiglottitis
how does acute epiglottitis present?
fever, sore throat leading to severe wheezing, drooling
when do disease manifestations of encapsulated H. influenza occur?
at 6 months to 3 years- after disappearance of maternal antibodies
what does unencapsulated haemophilus influenza cause?
otitis media
What are the general characteristics of Haemophilius ducreyi? (gram stain, shape, and requirements for growth)?
gram negative coccobacillus, X and V factors (hemin and NAD) required for growth
how does Haemophilius ducreyi look when stained?
clumping of bacteria likened to a school of fish
how is Haemophilius ducreyi transmitted?
sexually transmitted
what is the effect of Haemophilius ducreyi infection?
a painful genital ulcer known as a chancroid; can also cause a painful unilateral suppurative (pus forming) inguinal lymphadenopathy
where is haemophilius ducreyi endemic to?
developing regions in asia africa and caribbean
what organisms cause a painful genital lesion?
haemophilius ducreyi and HSIVI and II virus
what are the general characteristics of Garderella vaginalis? (gram stain and shape)
gram negative to variable rod
what is the effect of garderella vaginalis?
bacterial vaginitis
how does garderella vaginalis detected on pap smear?
as “clue cells”: squamous epithelial cells with mixed flora replacing normal flora
what is the presentation of infection of garderella vaginalis?
malodorous “fishy smelling” discharge, pruritus, and dysuria
What are the gram negative zoonotic bacilli? (4)
yersinia pestis, francisella tularensis, brucella species, and Pasteurella multocida
what are the facultative intracellular gram negative zoonotic bacilli?
Yersinia, Francisella, and brucella
what are the general characteristics of yersinia pestis? (gram stain, shape)
gram negative zoonotic rod; BIPOLAR SHAPE
what is historically known about yersinia pestis?
it was responsible for the bubonic plaque
what is the reservoir for yersinia pestis?
found in wild rodents and prairie dogs; transferred to rats during epidemics
what is the vector for yersinia pestis?
fleas
what were the symptoms of the bubonic plague?
hemorrhage under skin; lymph nodes become hot and painful, fever, headache
what happens/ what is the effect of yersinia pestis being spread by aerosolized particles from human to human?
a severe atypical pneumonia
what are the general characteristics of francisella tularensis? (gram stain and shape)
gram negative zoonotic rod
how is infection with francisella tularensis most commonly obtained?
by handling rabbits or via tick/deerfly bite
what are the effects of francisella tularensis?
ulceroglandular tularenia and pneumonic tularemia
how does ulceroglandular tularemia present?
similar presentation to bubonic plague except presents with a skin ulcer
what is the key difference between yersinia pestis and francisella tularemia?
a characteristic primary ulcer occurs at the site of the fly or tick bite in francisella
what are the general characteristics of brucella specieis? (gram stain and shape)
gram negative zoonotic rod
what causes brucella infections? Who is at risk?
those who have contact with domesticated animal products, drinking unpasteurized milk, contact with infected meats, placental tissue
what are the features of brucella infections?
undulant fever, headache, night sweats, joint and muscle pain, splenomegaly; hematologic abnormalities can occur including anemia and leukopenia
what is an undulant fever?
fever spikes during the day and decreases at night
What are the general characteristics of pasteurella multocida? (gram stain and shape)
gram negative zoonotic NOT INTRACELLULAR
where is pasteurella multocida found?
normal flora of cats and dogs; often results after bite or cat scratch
what is unique about pasteurella multocida when compared to the other gram negative zoonotic organisms?
it is a facultative anaerobe: it can cause localized wound infection (cellulitis)
What are the general characteristics of Bartonella species? (stain and shape)
gram negative rod
how is bartonella henselae transmitted?
by cat scratch or bite
what are the effects of infection with Bartonella henselae?
cat scratch fever; regional low grade fever, malaise, lymphadenopathy, it is self limiting
besides the febrile illness, what else can bartonella henselae cause?
bacillary angiomatosis
what is bacillary angiomatosis?
a vascular proliferative disease consisting of numerous small vascular lesions which occur in the immunocompromised
What are the obligate intracellular bacteria?
chlamydia species, Rickettsia species, Coxiella burnetti, and Ehrlichia chaffeensis
What are the general characteristics of chlamydia species? (stain, size, intra-extracellularity)?
gram negative, tiny obligate intracellular bacteria
what do chlamydia species have a predilection to?
mucosal epithelial cells
What is chlamydia trachomatis?
the most common bacterial sexually transmitted infection; exclusively a human pathogen
what is chlamydia trachomatis a common cause of?
neonatal blindness worldwide
how does transmission of chlamydia trachomatis occur?
through direct contact
What is the effect of chlaymydia trachomatis?
non-gonococcal urethritis: dysuria, discharge in men; dysuria, increased frequency in women; men can occasionally have epididymitis; women can have mucopurulent cervicitis leading to PID
What is trachoma?
a chronic eye infection caused by certain serotypes of chlamydia; spread by flies
What is lymphogranuloma venereum cause by?
caused by the L1, L2, and L3 serotypes of chlamydia trachomatis
what does lymphogranuloma venereum cause?
a tender suppurative (or pus forming) inguinal lymphadenitis which can ulcerate
besides chlamydia trachomatis, there are two other chlamydial organisms which can cause what?
Chlamydia pneumoniae and chlamydia psittaci- both cause atypical PNA
how does the mild atypical pneumonia caused by chlamydia present?
dry cough, low grade fever with patchy interstitial inflammatory changes
how is chlamydia pneumoniae PNA spread?
community acquired direct spread
how is chlamydia psittaci “psittacosis” atypical PNA spread?
transmitted from bird exposure (bird feces and dried out feathers)
what are the general characteristics of Rickettsia species? (gram stain and shape)
gram negative pleomorphic coccobacillus form
what are Rickettsia species transmitted by?
arthropod vectors
most rickettsia species are what test positive? and what does this mean?
Weil-Felix test positive: they show agglutination by OX antibodies
how do Rickettsia species present?
fever, headache, rash, thrombocytopenia
what does Rickettsia rickettsii cause?
Rocky mountain spotted fever
what is the vector for Rickettsia rickettsii?
ticks
what is the reservoir for Rickettsia rickettsii?
dogs, rabbits, wild rodents
what are the symptoms associated with R. Rickettsii infection aka rocky mountain spotted fever?
fever, headache, centripetal rash including palms and soles
where is R. rickettsii prevalent?
central and southeast US
causes of rickettsial infection also often show what?
thrombocytopenia
what does a centripetal rash mean?
it starts on the wrists and ankles and spreads to the trunk
What is unique about R. akari?
they are Weil-Felix negative
what is the most prominent sign of rickettsialpox?
a blister/eschar at bite site
What are the general characteristics of coxiella burnetti (Q fever)?
obligate intracellular gram negative bacteria
where is coxiella burnetti found?
in domesticated animals such as cattle, sheep, and goats
how can coxiella burnetti be transmitted?
through the dust and air especially during the birthing, killing, and butchering of animals
what does coxiella burnetti: Q fever present with?
fever, headache, atypical pna
What is ehrlichia chaffeensis?
tick born illness which causes ehrlichiosis
how does ehrlichiosis present?
it is a similar disease as rocky mountain spotted fever but typically NO RASH; fever headache malaise present
where is Ehrlichia chaffeensis common?
same range as rocky mountain spotted fever: southeast and central US
What is a general description of the spirochetes?
they are gram negative, corkscrew bacteria, with spinning motility and difficult to culture
What are the 3 different species in the spirochetes group?
treponema, borrelia, and leptospira
how are spirochetes diagnosed?
by dark-field microscopy, silver stains, and serologic testing
What is the main disease/illness caused by treponema pallidum?
syphilis
how is syphilis transmitted?
sexually transmitted disease by skin to skin contact
how does syphilis present? what are the stages of the illness?
- primary syphilis 2. Secondary syphilis 3. tertiary syphilis
what occurs in primary syphilis?
a painless chancre develops after 3-6 weeks of contact (typically in genital region)
what occurs in secondary syphilis?
6 weeks after the primary infection, individuals can get a condyloma lata, a macular red rash (on the palms and soles), patchy hair loss, lymphadenopathy
what occurs in tertiary syphilis?
6-40 years after secondary infection: gummatous lesions, thoracic aortic aneurysm, and neurosyphilis
what are the symptoms of neurosyphilis?
subacute meningitis, tabes dorsalis
when does tabes dorsalis occur and what is the effect?
occurs when syphilis affects the posterior columns of the spinal cord resulting in decreased coordination, loss of pain/temperature sensation, and diminished proprioceptive and vibratory sensation
what is Argyll robinson pupils?
syphilitis lesion involving the midbrain; pupil constrict to focus on near object but they do not react to light
infants with congenital syphilis present with what?
mucous membrane involvement in the first 3 weeks of life termed “snuffles”
what is secondary syphilis in infants?
rash including palms and soles, condyloma lata
what is the time frame for congenital syphilis?
within the first 2 years of birth
what is the time frame for late congenital syphilis?
> 2 years after birth
what are the findings of late congenital syphilis?
tertiary syphilis (cardiovascular typically spared); neurosyphilis (8th cranial nerve involvement deafness) bone and teeth involvement
what are the teeth defects seen in late congenital syphilis?
Hutchinson’s teeth: central tooth notching
what are the bone defects seen in late congenital syphilis?
Saber shins: bowing of the tibia
How do you diagnose syphilis if it is in the primary and secondary active forms?
dark field microscopy of chancre, rash, or condyloma latum
What does infection with Borrelia burgdorferi cause?
lyme disease
How is lyme disease transmitted?
by blacklegged Ixodes ticks
what is the reservoir for lyme disease?
deer
where is lyme disease commonly found?
northeast US, upper midwest
what is the most common tick borne illness?
Lyme disease
How does the early localized disease of lyme disease present?
10 days after tick bite: erythema migrans: bulls-eye rash at tick bite; flu like symptoms
what are the signs of early disseminated disease of lyme disease?
it can involve the nervous system, heart and joints; Bell’s palsy, neuropathy, or meningitis can occur
What is a big clue of early disseminated disease of lyme disease?
if there is a unilateral warm joint (especially the knee) with concomitant fever
What are the signs of late disease of lyme disease?
chronic arthritis and encephalopathy (memory impairment and somnolence)
What is a unique feature of mycobacterium?
they are acid fast
what are the 3 important mycobacteria?
m. tuberculosis, M. leprae, and M. avium complex
how is m. tuberculosis spread?
respiratory aerosolization from person to person
who is at more of a risk for m. tuberculosis?
immunocompromised especially HIV patients
what are the major countries with m. tuberculosis?
china, southeast asia, africa
what is the body’s response to mycobacterium?
cell mediated immune response- the mycobacterium is taken up by alveolar macrophages which activate a T helper 1 cell
what is the result of the cell mediated immune response to mycobacterium?
a necrotizing granulomata
In tuberculosis most of the damage is caused by what?
the necrotizing granulomata not the actual organism
what acts as the virulence factor for mycobacterium?
mycosides
what happens once tuberculosis is breathed in?
it travels to the distal portion of the airspaces when it often times implants in the middle lobe; primary infection begins in the lung
who is at risk for primary symptomatic tuberculosis?
immunocompromised, elderly, and young
how does primary symptomatic tuberculosis present?
fever, chest pain, hilar lymphadenopathy, and effusion
What is a Ghon complex?
a focus of subpleural tuberculosis with associated lymphadenopathy
What is secondary tuberculosis?
it arises from a previously infected host, often through reactivation of a latent infection
when might secondary tuberculosis appear?
months to years after the primary infection
how does secondary tuberculosis present?
insidious onset- low grade fever, night sweats, and hemoptysis
reactivated tuberculosis classically involves what?
the upper lobes of the lungs because of the relatively higher oxygen tension
what are two important patterns of spread of secondary tuberculosis?
Pott’s disease and miliary tuberculosis
what is miliary tuberculosis?
widespread disseminated disease throughout multiple organs with innumerable lesions throughout the organs
what is Pott’s disease?
involvement of tuberculosis of the spine
what is the most common extrapulmonary manifestation of tuberculosis?
Pott’s disease
how is tuberculosis diagnosed?
Screening: tuberculin skin test and interferon-gamma release assays
when might you suspect primary tuberculosis on chest x-ray?
if you identify a Ghon complex
when might you suspect secondary active tuberculosis on chest xray?
something in the uper lobes
what does m. leprae cause?
leprosy (hansen’s disease)
where is leprosy prevalent?
certain developing countries- india brazil and indonesia
what is m leprae carried in?
in armadillos in southern US
leprosy is a disease of primarily the skin and superficial soft tissue- why?
it preferentially grows at lower temperatures
there are different manifestations of leprosy including what two?
tuberculoid leprosy and lepromatous leprosy
what is occurring in tuberculoid leprosy?
a strong cell mediated response (THelper 1 and IFN-gamma)
what is the effect of the strong cell mediated response that is occurring in tuberculoid leprosy?
localized skin lesions, granulomatous inflammation; typically involves unilateral skin/nerve; loss of nerve sensation
what is occurring in lepromatous leprosy?
there is no or minimal cell mediated immune response
what is the result of the minimal cell mediated immune response that is occurring in lepromatous leprosy?
the organisms are allowed to replicate unchecked- skin lesions typically occur all over the body with disfigurement including loss of digits of the hand
Where is mycobacterium avium complex species found?
fairly ubiquitous in nature and even found in municipal water sources
what effect does MAC cause in immunocompetent people?
a very low grade non specific atypical PNA which presents with cough, general fatigue/malaise and maybe SOB
What is important to remember about MAC?
it is a very common opportunistic infection in HIV patients with CD4 T cell count less than 50
how does MAC infection present in HIV patients with CD4 T cell count less than 50?
unexplained weight loss, fever, diarrhea
what are the three bacteria without cell walls?
mycoplasma pneumoniae, mycoplasma genitalium, and ureaplasma urealyticum
what is the smallest bacteria?
mycoplasma pneumoniae
what is the effect of mycoplasma pneumoniae?
very mild or self limited bronchitis and PNA; it is a very common cause of atypical PNA in teenagers and young adults
how is mycoplasma pneumoniae diagnosed?
cold agglutinins
what is mycoplasma pneumoniae associated with?
erythema multiforme
what is erythema multiforme?
target looking lesions, first seen on the backs of hands/ tops of feet with eventual spread down the limbs towards the trunk
what does mycoplasma genitalium infection cause?
non-gonococcal urethritis
what does ureaplasma urealyticum infection cause?
non-gonococcal urethritis
