bacterial infection (S-Y) Flashcards
how are Salmonella serotypes be categorized?
-typhoidal (typhoid & paratyphoid fever) - Typhi, Paratyphi A, tartrate negative Paratyphi B, Paratyphi C
-nontyphoidal (acute diarrhea)
how are the Salmonella (nontyphoidal) transmitted?
animal reservoirs (domestic and wild)
- eating contaminated foods (dairy, eggs, meat, raw produce)
- drinking contaminated water
- contact with people who have a diarrheal illness
what increases the risk of nontyphoidal salmonella infection after exposure?
taking AB or antacid medication
what are the symptoms of nontyphoidal salmonella infection?
acute diarrhea (incubation 12-96 hours, but it can be more than 7 days)
abdominal cramps, fever, usually resolves without treatment after 1-7 days
what % of people develop bacteremia or focal invasive infection (osteomyelitis, meningitis, endovascular infection, septic arthritis) from nontyphoidal salmonella infection?
5% (higher among infants, older adults, immunocompromised)
ppl with atherosclerosis, hemoglobinopathies, or maligantn neoplasms - increased risk for extraintestinal infection
how to diagnose nontyph salmonella infection?
culture (routine stool culture, abscesses, blood, CSF, urine)
how to treat salmonellosis?
- most just supportive care - rehydration therapy
- AB not recommended for most with uncomplicated salmonellosis (does not shorten the duration of illness and can prolong bacterial shedding)
who should get AB treatment for salmonellosis?
Consider antibiotic therapy for patients with suspected invasive disease (e.g., patients with severe diarrhea, high fever, manifestations of extraintestinal infection) and for patients at increased risk for invasive disease (e.g., infants, older adults, people who are immunocompromised, patients with known atherosclerosis). For these populations, treat infections empirically until susceptibility results are available.
which empiric AB drug should be used for salmonellosis?
fluoroquinolones in adult travelers (resistance rising globally)
ceftriaxone - children and adults with invasive disease (resistance rare)
azithromycin can be used for children and is an alternative agent for adults
what causes tetanus?
Clostridium tetani - spore-forming, anaerobic, gram positive
tetanus is more common in which area?
in rural and agricultural regions; areas where contact with soil or animal excreta is likely; warm and moist environments; and areas where immunization against tetanus is inadequate.
which countries have not achieved maternal and neonatal tetanus elimination?
Afghanistan, Angola, Central African Republic, Guinea, Mali, Nigeria, Pakistan, Papua New Guinea, Somalia, Sudan, South Sudan, Yemen
what is average incubation period for tetanus?
- incuation on average 10 days (3-21 days)
- duration of the incubatino period is inversely related to the severity of symptoms –> shorter incuation = riskier
how do you classify tetanus symptoms?
generalized, localized, and cephalic
generalized: >80%, lockjaw, generalized spasms, risus sardonicus, opisthotonus
localized: muscle spasms confined to the injury site
cephalic: head or face wound and flaccid cranial nerve palsies
how does neonatal tetanus occur?
contaminated umbilical stumps and whose mothers are unimmunized or inadequately immunized
long term sequelae - behavioral, intellectual, and neurologic abnormalities
what is case-fatality ratios for generalized tetanus? localized tetanus?
25~100%
<1%
how to dianose tetanus?
clinical findings with epidemiologic support only
how to treat tetanus?
- tetanus immune globulin (TIG)
- aggressive wound care and debridement
- supportive care
- AB 7-10 days: metronidazole; alternative is IV penicillin G
- must be hospitalized in a quiet, dim room to minimize spasms
Under 7 years, which tetanus vaccine is available? how many doses for children?
DTaP (diphtheria-tetanus-acellular pertussis)
DT (diphtheria-tetanus)
Infants/children - 5 doses of DTaP at 2, 4, 6, 15-18 months, 4-6 years
from 10 years old, which tetanus vaccine is avaialbe?
-Tdap (tetanus-diphtheria-acellular pertussis)
-adolescent shoudl receive 1 dose of Tdap at 11-12 years of age
-Children 7 and up can receive Tdap for catch-up vaccination
for pregnancy what is the indication of tetanus vaccination?
27-36 weeks’ gestation
unvaccinated pregnant people should receive 2 doses of TTCV during their pregnancy
what is contraindication & precaution of tetanus vaccination?
- encephalopathy without an identifiable cause occurring within 7 days of a previous dose of DTP, DTaP or Tdap - for the pertussis component of the vaccines; can receive either DT or Td
- progressive or neurolgic disorder due to pertussis component
when do you get tetanus vaccination for wound management?
when do you get tetanus TIG for wound management?
TTCV: history of tetnus vaccine unknown or less than 3 previous doses
TIG: history of tetanus vaccine unknown or less than 3 previous doses and the wound is not clean/minor wound.
what is the causing agent of tuberculosis?
Mycobacterium tuberculosis complex - rod-shaped, nonmotile, slow-growing, acid-fast bacteria including M. bovis and M. tuberculosis hominis
how is the TB transmited?
- coughs, through the air
- unpasteurized dairy products from infected cattle (bovine TB - caused by M. bovis)
what is multidrug-resistant TB resistant to?
at least the 2 most effective drugs - isoniazid and rifampin
how to diagnose TB?
8-10 weeks after exposure, do tuberculin skin test (TST) or interferon-gamma release assay (IGRA)
how much % of people who are infected with TB progress to TB disease?
If not progress to TB disease, what happens?
5-10%
-if not progress, it remains inactive (latent TB infection) – no symptoms, cannot spread the infection to others
how long does it take TB to progress to TB?
weeks to decades after initial infection
what are the symptoms of TB?
70-80% cases are lung related; others bladder, bones and joints, brain and meninges, genitalia, kidneys, lymph nodes, pleura
prolonged cough, fever, hemoptysis, night sweats, decreased appetite, weight loss
when do you do pretravel and posttravel testing for TB?
- who anticipate possible prolonged exposure to TB - care for patients, work in health care facilities, prisons or jails, refugee camps, homeless shelters;
- who plan to stay in TB-endemic countries
which 3 methods are used for TB testing?
- culture methods - takes 2 weeks, can identify M. tuberculosis complex species
- microscopy - sputum smear or other body tissues or fluids - can see AFB (acid-fast bacilli) but cannot distinguish M. tuberculosis from nontuberculous mycobacteria
- Nucleic Acid Amplification Tests - less sensitive than culture but more sensitive than AFB smear; specific for M. tuberculosis complex - rapidly confirm diagnosis and help guide initial treatment until culture results return.
how to treat latent TB?
- 3 months once weekly isoniazid and rifapentine
- 4 months rifampin daily
- 3 months isoniazid and rifampin daily
- 6-9 months isoniazid daily
what are the interactions of rifampin with other meds?
interaction with oral contraceptives and certain antiretrovral medications
how to treat TB?
- isoniazid, rifampin, ethambutol and pyrazinamide for 2 months, then isoniazid and rifampin for additional 4 months
how to treat drug-resistant TB?
- older tx: 4-6 drugs for 18-24 months
- new tx: bedaquiline, pretomanid, linezolid (all oral) for 6 months
how to prevent TB?
Bacillus Calmette-Guerin (BCG) vaccine - at birth in countries with higher TB burdens
- but low and variable efficacy in preventing TB in adults
if you had BCG vaccine, which TB test is preferred?
IGRA - BCG might give false-positive TST results
how to prevent infections from Mycobacterium bovis and other foodborne pathogens?
avoid unpasteurized diary products
when do you do 2nd TST for travelers?
- if TST testing for the first time
- not needed if already been tested and found to have a negative result within the previous 2 years
- 2nd method - TST baseline negative –> retest 1-3 weeks after; if 2nd is negative then pt is not infected; if 2nd is positive, pt have skin test boosting, possibly because of previous M. tuberculosis infection
what is the infectious agent of typhoid fever and paratyphoid fever (=enteric fever)?
Salmonella enterica serotypes Typhi, Paratyphi A, Paratyphi B, and Paratyphi C
how do you differentiate Paratyphi B strains (2 distinct pathotypes)?
based on their ability to ferment tartrate
1. Paratyphi B - unable to ferment tartrate and is associated with paratyphoid fever
2. Paratyphi B var. L(+) tartrate(+) - ferments tartrate and is associated with gastroenteritis typical of nontyphoidal salmonellosis.
other than water and food, what would be the rare route of transmission of enteric fever?
sexual contact, MSM
how are enteric fever transmitted?
only humans - water or food by feces of person (a person can be acute, chronic, or asymptomatic carrier)
each year, how many cases are there for typhoid fever and paratyphoid fever worldwide?
how many death per year?
typhoid - 11-21 million cases
para - 5 million cases
135,000-230,000 deaths per year
which returning countries are most reported for enteric fever?
South Asia (Bangladesh, India, Pakistan), Africa, Latin America, SE Asia
lower risk regions - East Asia and the Caribbean
what is the incubation period for enteric fever?
6-30 days
what are the symptoms of enteric fever?
gradual onset - increase fatigue and a fever that increases daily from low-grade to 38-40 degress in 3-4 days.
fever lowest in AM, peaking late afternoon or evening.
all experience anorexia, headache, malaise.
abdominal pain, constipation, diarrhea are common. (more in children)
dry cough, fatigue, myalgias, sore throat
hepatospenomegaly often can be detected.
a transient, maculopapular rash of rose-colored spots can occasionally be seen on the trunk.
clinical presentation is often confused with malaria.
untreated, case-fatality ratios are 10-30%; treated <1%
serious complications of typhoid fever occur in 10-15% of hospitalized patients - GI hemorrhage, intestinal performation, encephalopathy
how to diagnose enteric fever?
blood culture (bacteremia) - a single culture is positive in only 50% of cases - multiple blood cultures might be required; cultures might need to be held and observed for up to 7 days before reporting a negative result
bone marrow culture - more invasive but increases the sensitivity to 80%, and is relatively unaffected by previous or concurrent AB use.
stool culture - usually not positive during the first week of illness and has less diagnostic sensitivity than blood culture.
rapid diagnostic tests are not very reliable.
what are the regional estimates for multidrug-resistant (MDR) Typhi in South Asia and Africa?
9%
35-59%
what is the treatment of choice for enteric fever?
fluoroquinolones (eg. cipro)- but resistance >90% returning from South Asia
Azithromycin and ceftriaxone are increasingly being used as empiric
patients with suspected typhoid fever who traveled to Iraq or Pakistan, or who did not travel internationally before their illness began, what is the empiric tx for uncomplicated & complicated illness?
uncomplicated: azithromycin
complicated: carbapenem
what is the empiric treatment of typhoid fever for travelers returning from most other countries then Iraq or Pakistan?
ceftriaxone
when do you consider treatment with alternative ABs for enteric fever or begin looking for a persistent focus of infection (e.g. an abscess, or an infection in a bone, joint, or other extraintestinal site)?
if fever do not subside within 5 days
how many % of relapse occurs after clinical recovery of enteric fever?
10%
what is the efficacy of typhoid vaccines?
50-80%
what are the new type of typhoic vaccines?
protein conjugated Vi vaccines (80% effective)
what is the age indication of oral Vivotif?
how often is the booster dose?
6 years and up
every 5 years
how to take vivotif?
- 1 caps every other day, with cool liquid no warmer than 37 degrees, 1 hour before a meal, 2 hours after meal
- no alcohol 1 hour before and 2 hours after
- complete at least 1 week before
contraindication of vivotif (Ty21a)?
pregnant, or immunocompromised people
how long do you need to wait to get oral typhoid (Ty21a) vaccine after antimicrobial agents? or vice versa?
72 hours
are there any interactions between oral typhoid and other live virus vaccines?
no
when should you take oral typhoid vaccine after oral cholera vaccine?
8 hours after
are there any interactions between oral Ty21a and immune globulin?
no
what causes yersiniosis?
yersinia species - facultative anaerobic gram - coccobacili
Yersinia enterocolitica (serogroups O:3, O:5, 27, O:8, and O:9)
Yersinia pseudotuberculosis
Yersinia pestis is not included (this causes plague)
how are Yersinia spp transmitted?
consuming or handling food - raw or undercooked pork ;
unpasteurized milk ;
drink untreated water ;
direct or indirect contact with animals through the fecal-oral route.
which animals are involved with Yersinia?
Pigs - major
domestic (dogs), farm (cattle), wild (deer) can also transmit
who is at greater risk for yersiniosis infection and severe disease?
ppl with high iron levels (e.g. hemochromatosis, thalassemia), including those on iron chelation treatment
which countries have cases reported for yersiniosis?
norther Europe - Scandinavia; Canada, Japan
what are the symptoms of yersiniosis?
incubation 4-6 days - gradual symptoms;
enterocolitis is the most common symptoms (abdominal pain, diarrhea- can be bloody and persist for several weeks), fever
sore throat can occur, particularly in children.
Mesenteric adenitis (pain mimicking appendicitis).
Necrotizing enterocolitis in young infants.
reactive arthritis affecting the wrists, knees, and ankles can occur, usually 1 month after the initial diarrhea episode, resolving after 1-6 months.
erythema nodosum, manifesting as painful, raised red or purple lesions along the trunk and legs, can occur, and usually resolves spontaneously within 1 month.
how to diagnose Yersoniosis?
isolate the organism from bile, blood, CSF, mesenteric lymph nodes, peritoneal fluid, stool, a throat swab, or wounds.
Culture-independent diagnostic tests (CIDTs) now available.
culture needed for antimicrobial susceptibility testing.
how to treat yersiniosis?
self-limited
moderate to severe - AB; aminoglycosides, third-generation cephalosporins, fluoroquinolones, tetracyclines, trimethoprim-sulfamethoxazole
- typically resistant to 1st gen cephalo and most penicillins.
