bacterial infection (D-M) Flashcards
which bacteria causes diphtheria?
- toxigenic strains of Corynebacterium diphtheriae biotype mitis, gravis, intermedius, or belfanti.
- toxigenic strains of C. ulcerans also cause rare cases of a diphtheria-like illness.
how does diphtheria get tramismitted?
person-to-person - respiratory dropelts or direct contact with secretions
where is diphtheria endemic to?
Haiti, Dominican Republic, Asia and South Pacific, Eastern Europe, the Middle East
Since 2016, respiratory diph outbreak occurred in Bangladesh, Burma (Myanmar), Haiti, Indonesia, S Africa, Ukraine, Venezuela, Vietnam, Yemen
Cutnaneous diph common in tropical countries
symptoms of diphtheria?
- incubation period 2-5 days
- respiratory diph: gradual onset, mild fever (38.3), sore throat, difficulty swallowing, malaise, loss of appetite, hoarseness; pseudomembrane (firm, fleshy, grey, adherent) - 5-10% fatal
how to diagnose diphtheria?
culture taken from area and test for toxin production by the Elek test.
how to treat diphtheria
- hospitalization required!
- DAT (equine diphtheria antitoxin)
- AB: erythromycin or penicillin
- supportive care
- close contacts of patients should receive AB prophylaxis with erythromycin or penicillin
which E. coli pathoptypes are associated with diarrhea?
ETEC, STEC, EPEC, EAEC, EIEC, (DAEC)
ETEC: enterotoxigenic
STEC: shiga toxin-producing, also called verotoxigenic (VTEC); eterohemorrhagic E.coli (EHEC) is commonly used to specify STEC strains capable of causing human illness, especially bloody diarrhea and hemolytic uremic syndrome (HUS)
EPEC: enteropathogenic
EAEC: enteroaggregative
EIEC: enteroinvasive
DAEC: diffusely adherent
how does diarrheagenic E. coli pathotypes can be trasmitted?
feces of humans and other animals; fecal-oral
humans - non-STEC pathotypes
animals (cattle and other ruminants) - STEC
what is the global burden of diarrheagenic E.coli?
111 million illnesses, 63,000 deaths / year
ETEC are associated with travel to low- and middle-income countries
which countries has high risk for traveller’s diarrhea?
Afhanistan, Burma (Myanmar), the Indian subcontinent, Indonesia, Iran, Malaysia, Mexico, Papua New Guinea, most countries in Africa, countries in Central America and northern South America, including Bolivia and Paraguay
what is incubation period of non-STEC diarrheagenic E.coli and STEC?
8 hours to 3 days for non-STEC
3-4 days for STEC
what is the symptoms of STEC, and how to diagnose STEC infection? why is it important to diagnose STEC?
watery diarrhea that progresses to bloody diarrhea in 1-3 days (often for STEC O157) ; abdominal cramps and tenderness; fever low-grade, if present
stool samples - test for Shiga toxins or the genes that encode them
Hemolytic uremic syndrome complicates ~6% of diagnosed STEC O157 infections (15% kids <5 years) and 1% of non-O157 STEC infections)
how to treat diarrheagenic E.coli?
hydration and electroylte balance
loperamide - if mild and non-bloody diarrhea
AB - moderate to severe diarrhea
why is azithromycin preferred over fluoroquinolones for traveler’s diarrhea?
less resistant - fluoroquinolone resistance increase in Asia
fluoroquinolone side effect: tendinopathies, QT interval prolognation, C. diff enterocolitis
what do you need to do if AB treatment does not improve diarrhea within 24 hours?
- continue AB for no longer than 3 days
- 3-day rifaximin is effective for some non-bloody diarrheal illnesses.
- if STEC suspected, certain AB can increase risk of developing HUS (hemolytic uremia syndrome); IV fluids withing the first 4 days of diarrhea onset) might decrease the risk of oligoanuric renal failure
is there a vaccine for E.coli infection?
no vaccine is available.
what is helicobacter pylori?
gram -, rod-shaped, small, curved, microaerophilic
how does H. pylori trasmitted?
fecal-oral route, oral-roal possible
what illness does H. pylori infection cause?
peptic ulcer disease, gastritis, risk factor for non-cardia gastric adenocarcinoma (2-6 times increased risk of developing gastric cancer and mucosal assoicated-lymphoid-type (MALT) lymphoma)
how to diagnose H.pylori?
fecal antigen assay, urea breath test, rapid urease test, histology of a biopsy specimen
A positive serology indicates present or past infection
how to treat h. pylori?
standard - bismuth quadruple therapy
- PPI or H2 blocker, bismuth, metronidazole, tetracycline
Clarithromycin triple therapy: in regions where clarithromycin resistance is <15% and in patients with no previous history of macrolide exposure
- PPI, clarithromycin, amoxicillin or metronidazole
Refractory cases: combination tx with rifabutin
what is Legionnaires’ disease and Pontiac fever caused by ?
genus Legionella - gram negative - most cases of Legionnaires’ disease are caused by Legionella pneumophila
how dose Legionnaires’ disease trasmitted?
inhalation of aerosolized water containing the bacteria
freshwater; warm water, water stagnation, presence of scale, sediment, and biofilm in the pipes and fixtures, absence of disinfectant
potable water (via showerheads and faucets), cooling towers, hot tubs, decorative fountains
which country is Legionnaires’ disease affected?
worldwid
who is at risk of getting Legionnaire’s disease?
> 50 years, current or former smokers, chronic lung conditions, immunocompromised
what are the symptoms of Legionnaires’ disease?
severe pneumonia - fatal 10%
symptoms onset occurs 2-10 days after exposure
<5% of people exposed to the source of the outbreak develop Legionnaires’ disease
what is the difference between Legionnaires’ disease and Pontiac Fever?
Pontiac Fever is milder than Legionnaires’ disease and presents with fever, headache, or muscle aches, but no signs of pneumonia.
- symptoms occur within 72 hours of exposure
- fully recover without AB drug therapy or hospitalization
- upto 95% of ppl exposed during outbreaks of Pontiac fever can develop symptoms of disease.
how to diagnose Legionnaires’ disease?
Legionella urinary antigen test and culture of lower respiratory secretions (sputum, bronchoalveolar lavage)
- urinary antigen test only detects L. pneumophila serogroup 1; 80-90% of cases
- Legionella spp. cannot be isolated in people who have Pontiac fever.
how to treat Legionnaires’ disease?
AB stat - fluoroquinolones and macrolides
how to prevent Legionnaire’s disease?
water management programs and devices
what is the causative agent of leptospirosis?
Leptospira spp - obligate aerobic, gram negative spirochete bacteria
how are Leptospira trasmitted?
abrasions or cuts in the skin or through the conjuctiva and mucous membranes; macerated skin resulting from prolonged water exposure
direct contact with urine or reproductive fluids from animals (rodents!! dogs, horses, cattle, swine, many wildlife species), urine-contaminated freshwater sources or wet soil
eating contaminated food or water
rarely through animal bites or human-to-human contact
what is the distrubtion of Leptospirosis?
worldwide - but greater in tropical climates
highest morbidity and mortality - sub-Saharan Africa, parts of Latin America, and in the Caribbean, South and Southeast Asia, Oceania
who is at increased risk of Leptospirosis?
participate in recreational freshwater activities (boating, swimming) after heavy rainfall or flooding
participate in activities involving mud (adventure races)
working directly with animals in endemic areas
what is the global burden of Leptospirosis?
> 1 million cases, ~59,000 deaths per year
what is the incubation period of Leptospirosis? what is the severity of most cases?
- incubation 2-30 days (usually 5-14 days)
- self-limiting acute febrile illness ~90%; severe, potentially fatal illness with multiorgan dysfunction in 5-10%
Leptospirosis has biphasic phase - acute and second phase. what are the symptoms of acute or septicemic phase? how long does it last?
- biphasic
1) acute phase or septicemic phase: ~7 days - fever, headache, photophobia, retro-orbital pain, chills, myalgias, characteristically involving the calves and lower back; conjunctial suffusion, vomitting, diarrhea, abdominal pain, cough, skin rash
Leptospirosis has biphasic phase - acute and second phase. what are the symptoms of second or immune phase?
2) second or immune phase: antibody production and the presence of leptospires in the urine, cardiac arrhythmias, hemodynamic colapse, hemorrhage, jaundice, liver failure, aseptic menigitis, pulmonary insufficiency, renal failure - Weil’s disease - renal and liver failure
what is the case-fatality ratio of patients with severe Leptospirosis disease ?
what is the fatality ratio of severe pulmonary hemorrhagic syndrome, a rare form of leptospirosis?
- 5-15%
- > 50%
what is poor prognostic indicators of leptospirosis?
older age, altered mental status, respiratory insufficiency, or oliguria
how to diagnose leptospirosis?
serum samples - acute and convalescent sample pairs
serology; microscopic agglutination test (MAT)
culture is insensitive, slow and requires special media; therefore not recommended as the sole diagnostic method
how to treat Leptospirosis?
AB stat
mild - doxycycline (other alternative - ampicillin, amoxicillin, or azithromycin)
severe - IV penicillin (cefriaxone and cefotaxime are alternative)
what is Jarisch-Herxheimer reaction?
AB treatment of spirochetal diseases including leptospirosis can cause this - rarely fatal
a sudden and typically transient reaction that may occur within 24 hours of being administered antibiotics for an infection by a spirochete, including syphilis, leptospirosis, Lyme disease, and relapsing fever.[1] Signs and symptoms include fever, chills, shivers, feeling sick, headache, fast heart beat, low blood pressure, breathing fast, flushing of skin, muscle aches, and worsening of skin lesions.[1] It may sometimes be mistaken as an allergy to the antibiotic.[1]
how to prevent leptospirosis?
avoid exposure
protective measures - clothing, footwear, covering cuts, etc., boiling or chemically treating water
chemoprophylaxis - doxy 200mg weekly 1-2 days before and continue through the period of exposure
no vaccine
what infectious agent cause Lyme disease?
Borrelia burgdorferi sensu lato complex -
including B. afzelii, B. burgdorferi sensu stricto, and B. garinii
Which ticks cause Lyme disease?
Ixodes (blacklegged) ticks - typically immature (nymphal) ticks - small, size of a poppy seed, elude easy detection
patients might be unaware that they were even bitten
which area is Lyme diseaseas at risk?
In Europe - endemic from southern Scandinavia into the northern Mediterranean countries of Greece, Italy, and Spain, and east from the British Isles into central Russia.
Incidence is greatest in central and eastern European countries.
Asia - western Russia through Mongolia, northeastern China, and into Japan
North America - northeastern and north-central US
what is the incubation time of Lyme disease?
what are the symptoms?
3-30 days
erythema migrans (EM) within 30 days of exposure - red, expanding rash, with or without central clearing, often accompanied by symptoms of fatigue, fever, headache, mild stiff neck, arthralgia, or myalgia
within days or weeks - infection can spread to other parts of the body - serious neurologic conditions (meningitis, radiculopathy, facial palsy) or cardiac abnormalities (myocarditis with atrioventricular heart block)
if not treated - progress over several months (to years) to cause monoarticular or oligoarticular arthritis, peripheral neuropathy, or rarely, encephalopathy
what is European strains of Borrelia can result in?
lymphocytoma, an acute blister-like lesions, and acrodermatitis chronica atrophicans, characterized by atrophic patches of bluish-red skin that develop over a period of years and typically involve the extremities
how to diagnose Lyme disease?
- history of recent traveling
- identifying EM rash
- for patients with evidence of disseminated infection (cardiac, musculoskeletal, neurologic manifestaitons), serologic testing using commercial assays can aid in diagnosis
how to treat Lyme disease?
doxycycline, amoxicillin, or cefuroxime axetil
IV ceftriaxone
what bacteria cause melioidosis?
Burkholderia pseudomallei; gram - ; bacillus - found in soil and water in tropical and subtropical countries
how do you get Burkholderia psudomallei (or melioidosis) transmitted?
through damaged skin (open wounds, cuts, burns) or mucous membranes.
contact with contaminated soil or water
can be transmitted by ingestion and inhalation as well. (through untreated water and raw or undercooked food)
where does Meliodosis most likely occur?
SE Asia and Northern Australia -
Burkholderia pseudomallei is endemic to SE Asia, Papua New Guinea, Indian subcontinent, southern China, Hong Kong, Taiwan.
Highly endemic to NE Thailand, Malaysia, Singapore, northern Australia
also found in the Americas, including the Caribbean and the Gulf Coast of the US (Mississippi);
sporadic cases to Aruba, Brtish Virgin Islands, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Guadeloupe, Guyana, Honduras, Martinique, Mexico, Panama, Peru, Puerto Rico, US Virgin Islands, Venezuela, northeastern Brazil
what type of travelers is at most risk for meliodosis?
adventure travelers, construction and resource extraction workers, ecotourists, military personnel, and other people whose contact with contaminated soil and water might expose them to the bacteria.
what are the risk factors for developing meliodosis? (chronic disease?)
diabetes, excessive alcohol use, chronic lung disease (COPD or cystic fibrosis), chronic renal disease, thalassemia, malignancy, other non-HIV-related immune suppression
what are the symptoms of meliodosis?
incubation 1-21 days (avg 4 days) –> can remain latent for months or years before symptoms develop
localized infection, pneumonia, bacteremia, or disseminated infection involving any organ, including the brain.
nonspecific symptoms - abdominal discomfort, abscesses or ulcerations, chest pain, cough, respiratory distress, disorientation, headache, seizures; fever; localized pain and swelling; muscle or joint pain; weight loss
generally acute illness but 9% present with more than 2 months of symptoms.
chronic meliodosis often mimics Mycobacterium tuberculosis infection clinically.
how to diagnose meliodosis?
collect specimens from all relevant infection sites for culture - blood, cerebrospinal fluid, pericardial fluid, peritoneal fluid, purulent exudate, sputum, synovial fluid, urin, throat and rectal swabs
IHA (indirect hemagglutination assay) is widely used
no serologic can perform confimation
how to treat meliodosis?
long term AB therapy (acute phase - eradication phase)
Acute treatment; IV ceftazidime, or meropenem for severe cases with sepsis for min 14 days, upto 8 weeks if severe
Eradication treatment: TMP-SMX or Amoxi-Clav
which bacteria causes meningococcal disease?
Neisseria meningitidis - Gram -, diplococcus bacterium
how are the Meningococci classified into serogroups ?
based on composition of their capsular polysaccharide - ABCWXY
where are N. miningitidis found?
worldwide, but greatest in “meningitis belt” of sub-Saharan Africa - esp. dry season (Dec-June)
1000 cases per 100,000
rates of disease in Australia, Euorope, South America, and the US range from 0.10-2.4 cases per 100,000 population per year
how does meningococci spread?
respiratory secretions, close contact
asymptomatic carriers (5-10% of population) & ppl with overt miningococcal disease
which serogroup of meningococcal bacteria cause outbreaks in the meningitis belt?
A before MenAfriVac (conjucate vaccine) came, but now C and W and also X have been reported
which age group has the highest rates of meningococcal disease outside the meningitis belt?
which age group in meningitis belt?
- infants, adolescents, adults over 80 years
- <30 years, in children and adolescents aged 5-14 years
which countries are in mengitis belt?
Senegal, The Gambia, Guinea-Bissau, Guinea, Cote D’Ivoire, Mauritania, Mali, Burkina Faso, Ghana, Benin, Togo, Niger, Nigeria, Cameroon, Chad, Central African Republic, Sudan, South Sudan, Democratic Republic of the Congo, Uganda, South Sudan, Ethiopia, Eritrea, Kenya
what are the symptoms of meningococcal disease?
1-10 days after exposure - presents as meningitis in 50% of cases in US; case fatality 10-15% even with AB treatment.
sudden onset of headache, fever, neck stiffness, sometimes accompanied by nausea, vomiting, photophobia, or altered mental status
what is meningococcemia?
meningococcal sepsis - approx. 30% with meningococcal disease present with this.
abrupt onset of fever, chills, vomiting, diarrhea, petechial or purpuric rash, which can progress to purpura fulminans
hypotension, acute adrenal hemorrhage, multiorgan failure
what do people present with when they have meningococcal disease?
50% meningitis
30% meningococcemia
15% bacteremic pneumonia (primarily >65 years)
nonspecific symptoms (infants and < 2year old) - neck stiffness might be absent in this age group
how do you diagnose meningococcal disease?
- collect blood for culture STAT or PCR detection of N. meningitidis-specific nucleic acid
- lumbar puncture (LP) to collect CSF
how to treat meningococcal disease?
3rd gen cephalosporins for empiric treatment
-after susceptibility determined, can switch to ampicillin or penicillin
if suspected bacterial meningitis of uncertain etiology, some recommend empiric use of dexamethasone in addition - if meningococcal meningitis is confirmed or suspected, steroids can be discontinued.
what are meningococcal vaccines available in US?
5 vaccines - 3 quadrivalent (ACWY), 2 monovalent (B)
Menveo, Menactra, MenQuadfi
Trumenba, Bexsero
when should travellers receive meningococcal vaccines?
7-10 days before travel
if you initiate menigococcal vaccine (Menveo) at age 2 months, what is the schedule after that?
4 dose series - 2 months, 4 months, 6 months, 12 months
if you initiate Menveo at 3-6 months, what is the schedule after that?
3-6 months, 1 dose every 8 weeks until the infant is 7 months old, then give 1 additional dose after the infant is 12 months old.
if you initiate Menveo at 7-23 months, what is the schedule after that?
if you initiate Menveo at 2 years old, what is the schedule after that?
2 dose: 7-23 months, then 12 weeks after dose 1 and the child is 12 months old.
1 dose: > 2 years 1 dose only
what is Menactra schedule for baby 9-23 months old and 2 years old?
2 dose: 9-23 months old and 12 weeks after
1 dose: for 2 years old
what is the MenQuadfi schedule for baby 2 years old?
1 dose only
what is the schedule for Trumenba (Pfizer)?
2 doses: 10-25 years, then 6 months after
what is the schedule for Bexsero(GSK)?
2 dose: 10-25 years, then 1 months after
what is the routine immunization of quadrivalent minigococcal conjugate vaccine (MenACWY) for all people aged 11-18 years?
After that age?
1 dose at 11 or 12 years
booster at 16 years
after age 16, only with a persistent complement component deficiency, ppt taking a complement component inhibitor (eculizumab or ravulizamab), ppl with functional or anatomic asplenia, ppl with HIV
what is recommended MenB vaccine age group?
age 16-23 years
age 10 years and older: if increased risk with persistent complement component deficiency and those with functional or anatomic asplenia
who should get vaccinated with MenACWY vaccines when traveling?
2 years or older, visiting meningitis belt of sub-Saharan Africa during dry season (12-6)
other countries if outbreak
The Kingdom of Saudi Arabia (KSA) requires travelers 1 year or older making the Umrah or Hajj pilgrimage to provide documentation of quadrivalent vaccine 10 or more days and equal to or less than 3 years before arrival for polysaccharide vaccine MPSV4) and 5 or less years before arrival for conjugate vaccine.
Pregnancy and children should receive vaccine
for children who completed the primary dose or series at <7 years of age, aminister a booster dose after 3 years and repeat Q5 years for those who live in or travel to hyperendemic areas.
for people who received the primary dose or series at 7 years or older, administer a booster dose after 5 years and Q5 years thereafter for people who live or travel to a hyperendemic area.
MenB vaccine is not routinely recommended (extremely rare) for travelers unless an outbreak of serogroup B
what are some side effects of MenACWY vaccination?
low-grade fevers, local reactions, resolve within 2-3 days - severe adverse reactiosn (high fever, chills, joint pain, rash, seizures) are rare (<5%)
what antibiotics are used for prophylaxis for close contacts of a patient with invasive meningococcal disease?
cetriaxone, ciprofloxacin, rifampin
