Bacterial Enteric Infections Flashcards
What factors may increase the risk of enteric bacterial infections in individuals with HIV?
HIV-associated alterations in mucosal immunity, intestinal integrity, and treatment with acid-suppressive agents
Rates of Gram-negative bacterial enteric infections are at least 10 times higher among adults with HIV than in the general population.
Which bacteria are most frequently isolated by culture from adults with HIV in the United States?
- Shigella
- Campylobacter
- nontyphoidal Salmonella spp.
Particularly Salmonella enterica serotypes Typhimurium and Enteritidis.
What is the relationship between CD4 T lymphocyte count and the risk of bacterial diarrhea in individuals with HIV?
The risk of bacterial diarrhea is greatest in individuals with clinical AIDS or CD4 counts <200 cells/mm3.
What is a common condition associated with Clostridioides difficile in people with HIV?
Clostridioides difficile–associated infection (CDI)
Low CD4 count (<50 cells/mm3) is an independent risk factor.
What defines severe community-associated diarrhea in people with HIV?
Six or more loose stools per day with or without other signs of systemic illness.
What is the recommended method for diagnosing Gram-negative bacterial enteric infections?
Cultures of stool and blood or stool molecular methods (culture-independent diagnostic tests).
What is the significance of obtaining blood cultures in patients with diarrhea and fever in the context of HIV?
High incidence of bacteremia associated with Salmonella gastroenteritis in people with HIV.
What is the role of endoscopy in diagnosing enteric infections in people with HIV?
Reserved for cases where stool culture, microscopy, and other tests fail to reveal an etiology.
What precautions should be taken to prevent enteric infections in individuals with HIV?
- Wash hands regularly with soap and water
- Use of barriers during sexual practices
- Avoid contact with human feces
Soap and water are preferred over alcohol-based cleansers.
What immunizations are recommended for travelers at risk of bacterial enteric infections?
Immunizations against Salmonella serotype Typhi.
What is the recommended treatment for people with HIV and CD4 count 200–500 cells/mm3 experiencing diarrhea?
- Azithromycin 500 mg PO daily for 5 days
- Ciprofloxacin 500–750 mg PO every 12 hours for 5 days.
What is a key consideration when treating bacterial enteric infections in people with HIV?
Diagnostic fecal specimens should be obtained before initiation of empiric antimicrobial therapy.
Fill in the blank: The risk of a bacterial enteric infection increases as CD4 count ______.
<200 cells/mm3.
What should be considered if no clinical response occurs after 3 to 4 days of therapy for bacterial enteric infections?
Follow-up stool culture with antibiotic susceptibility testing and other methods to detect enteric pathogens.
True or False: Antimicrobial prophylaxis to prevent bacterial enteric illness is routinely recommended for travelers.
False.
What are the potential adverse effects of routine use of fluoroquinolones for prophylaxis in enteric infections?
Toxicity associated with CDI and increasing rates of antimicrobial resistance.
What is the preferred agent for prophylaxis in pregnant people traveling to areas at risk for bacterial enteric infections?
Azithromycin.
What clinical syndromes are associated with Gram-negative enteric bacteria among people with HIV?
- Self-limited gastroenteritis
- Severe and prolonged diarrheal disease
- Bacteremia with or without gastrointestinal illness.
What should be included in the assessment of patients with diarrhea in the context of HIV?
Complete exposure history, medication review, stool frequency and consistency, associated signs and symptoms.
What is the importance of reflex stool cultures and antibiotic sensitivity testing?
To address increasing resistance detected in enteric bacterial infections.
What is the definition of diarrhea for testing C. difficile infection (CDI)?
Three or more loose stools in 24 hours.
What is the initial treatment for suspected bacteremia in patients with HIV?
Ceftriaxone 1–2 g IV every 24 hours until susceptibility results are available
This treatment can be adjusted based on sensitivity results.
When is a carbapenem preferred for empiric therapy?
When Campylobacter or Shigella bacteremia is suspected
This is to ensure effective treatment in potentially resistant cases.
What is the recommended duration of therapy if no pathogen is identified and the patient recovers quickly?
5 days of therapy is recommended
This duration may vary based on stool microbiology results.
What is the increased risk of bacteremia in patients with HIV and salmonellosis?
20- to 100-fold increased risk
Mortality can be increased by as much as sevenfold.
What is the preferred therapy for Nontyphoidal Salmonella gastroenteritis if susceptible?
Ciprofloxacin 500–750 mg PO (or 400 mg IV) every 12 hours
This is the first-line treatment for susceptible cases.
What should be the duration of therapy for gastroenteritis without bacteremia in patients with CD4 count ≥200 cells/mm3?
7–14 days
Duration may extend depending on patient conditions.
What is the recommended therapy for gastroenteritis with bacteremia in patients with CD4 count <200 cells/mm3?
2–6 weeks of therapy
The duration may be longer if the infection is complicated.
Is secondary prophylaxis for recurrent bacteremia or gastroenteritis well established?
No, it is not well established
Clinicians must weigh the benefits against the risks of long-term antibiotic exposure.
What is the preferred initial therapy for Shigellosis if the patient is severely ill?
Initiate a carbapenem while awaiting susceptibility results
This approach is to ensure effective treatment during critical situations.
What is the recommended duration of therapy for Shigellosis gastroenteritis?
5–7 days
Ciprofloxacin may be given for 5 to 10 days if susceptible.
What is the first-line therapy for Clostridioides difficile–associated infection?
Fidaxomicin 200 mg PO two times per day for 10 days
This is the preferred treatment for CDI.
What alternative therapy can be used for nonsevere CDI?
Metronidazole 500 mg PO three times per day for 10 days
This is recommended if fidaxomicin or vancomycin is unavailable.
What should be avoided in the first trimester of pregnancy regarding antibiotic use?
TMP-SMX should be avoided if possible
It is associated with increased risk of birth defects.
What is the recommended therapy for mild Campylobacteriosis if diarrhea resolves before culture confirmation?
Antibiotic treatment can be withheld
If symptoms persist, consider antibiotic therapy.
What is the duration of therapy for bacteremia in Campylobacteriosis?
≥14 days
This is critical for effective management.
What should be considered for chronic maintenance or suppressive therapy for Shigella infections?
Not recommended for first-time Shigella infections
This approach helps prevent unnecessary long-term antibiotic use.
What is the role of ART in patients with recurrent bacteremia or gastroenteritis?
HIV suppression with ART is expected to decrease the risk of recurrent illnesses
ART helps manage HIV effectively.
What is the effect of diarrhea on temporary malabsorption in patients with HIV?
Diarrhea can produce temporary malabsorption or lactose intolerance
A bland diet is recommended to alleviate symptoms.
What is the treatment of choice for susceptible nontyphoidal Salmonella spp. infection?
Fluoroquinolone, preferably ciprofloxacin
Alternatives include levofloxacin and moxifloxacin.
What is recommended if invasive disease is suspected or confirmed in nontyphoidal Salmonella infection?
Ceftriaxone over ciprofloxacin
Recommended until susceptibilities return.
What is the recommended treatment duration for patients with CD4 counts ≥200 cells/mm3 and mild gastroenteritis from Salmonella?
7 to 14 days
If bacteremia is present, 14 days is appropriate.
For patients with advanced HIV disease and Salmonella infection, what is the minimum recommended treatment duration?
2 weeks, extendable up to 6 weeks
Especially in severe disease or bacteremia.
True or False: Secondary prophylaxis should be considered for patients with recurrent Salmonella bacteremia.
True
Also considered for patients with recurrent gastroenteritis.
What should be monitored in people with HIV and Salmonella bacteremia after treatment?
Clinical recurrence
Recurrence may present as bacteremia or localized infection.
What is the preferred treatment for susceptible Shigella infections?
Fluoroquinolone, preferably ciprofloxacin
Treatment duration is typically 5 to 10 days.
What percentage of Shigella spp. isolated in the U.S. in 2023 harbored genetic markers of resistance to ciprofloxacin?
60%
Azithromycin resistance was also reported at 34%.
What is the recommended treatment for Campylobacter bacteremia?
At least 14 days with a fluoroquinolone if sensitive
Azithromycin is not recommended for Campylobacter bacteremia.
Fill in the blank: The treatment of CDI in people with HIV is _______.
the same as in people without HIV
Available data suggest similar responses to treatment.
What is the recommended treatment for an initial episode of CDI?
Fidaxomicin rather than oral vancomycin
Both treatments are acceptable, but fidaxomicin is preferred.
What monoclonal antibody is approved for prevention of recurrent CDI?
Bezlotoxumab
It is used in conjunction with standard antibiotic therapy.
What should be considered when initiating ART in the presence of an enteric infection?
Initiation should not be delayed
It is relevant only for the patient’s ability to absorb ART.
What is recommended for monitoring patients after treatment for enteric infections?
Monitor for improvement in symptoms and resolution of diarrhea
Follow-up stool testing may be required in certain cases.
What is the risk factor for CDI recurrence?
Age ≥65 years, history of CDI, compromised immunity
Severe CDI and certain virulent strains also increase risk.
What should be done if recurrent enteric infections are documented?
Prompt initiation of ART should be considered
This applies regardless of CD4 count.
What should be avoided when coadministering fluoroquinolones?
Magnesium- or aluminum-containing antacids
These agents interfere with fluoroquinolone absorption.
What should be considered when treating ic infections in patients with HIV?
The patient’s immune status, exposures, and the possibility of C. difficile or antimicrobial resistance
Observational studies indicate a connection between severe diarrhea or malabsorption and decreased plasma drug concentrations in people with HIV.
What should be avoided when coadministering fluoroquinolones?
Magnesium- or aluminum-containing antacids, calcium, zinc, or iron
These agents interfere with fluoroquinolone absorption.
What is the recommendation for using antibiotics in clinically unstable patients?
Use IV antibiotics
This is suggested due to the potential impact of severe diarrhea on antibiotic absorption.
Has immune reconstitution inflammatory syndrome been described with typical bacterial enteric pathogens treatment?
No
What is a pharmacologic approach for preventing recurrent enteric infections?
Consider secondary prophylaxis for recurrent Salmonella bacteremia, recurrent shigellosis, or campylobacteriosis
This is outlined in the section on directed therapy for each bacterial species.
What is the first-line therapy for bacterial enteric infections during pregnancy?
Expanded-spectrum cephalosporins or azithromycin
This depends on the organism and susceptibility testing results.
What risk has been noted with quinolone use during pregnancy?
Arthropathy in offspring of animals treated with quinolones
However, studies in humans did not find increased birth defect risks.
What should be avoided in the first trimester of pregnancy?
TMP-SMX use
This is due to its association with increased risk of birth defects.
What is recommended for individuals on TMP-SMX prior to or during early pregnancy?
Supplemental folic acid 4 mg/day
This should be given to those capable of becoming pregnant.
What should neonatal care providers be informed about regarding maternal sulfa therapy?
The use of sulfa therapy near delivery due to the risk of hyperbilirubinemia and kernicterus in the newborn.
Can oral rifaximin and fidaxomicin be used in pregnancy?
Yes
These are not absorbed systemically.
What is the use of intravenous vancomycin in the perinatal period?
Intrapartum prophylaxis in penicillin allergic patients colonized with group B streptococcus.
What should be noted about oral vancomycin for enteric disease?
It is recommended only in its oral formulation, which is not absorbed systemically
Intravenous vancomycin crosses the placenta.
What did a study find regarding infants exposed to maternal intravenous vancomycin therapy?
No hearing loss or renal toxicity was attributed to vancomycin.
What was the finding regarding metronidazole use in pregnancy?
No increase in risk of birth defects was found
This was for treatment of trichomoniasis or bacterial vaginosis.
Have studies been found on metronidazole for CDI in pregnancy?
No
