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alimentary tract 1 (Clostridium difficile (Risk factors (antimicrobial…
alimentary tract 1
Clostridium difficile
- spore-forming, toxin-producing, gram-positive anaerobic bacterium that causes antibiotic-associated colitis
- Antibiotic-associated diarrhea and colitis were well established soon after widespread use of antibiotics
- C. difficile infections are frequent, severe, refractory to standard therapy, and likely to relapse than previously described
Transmission
- spores are stable to oxygen stress, temperature extremes, desiccation, disinfectants, alcohol-based hand sanitizers
- spores common in water, soil, meats, and vegetables
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Risk factors
antimicrobial
- antimicrobial exposure: including
duration (increased risk with increased days), number (risk increases with number), class
of antimicrobial agents
- highest risk: clindamycin, fluoroquinolones, cephalosporins of second generation and higher
- moderate risk: penicillins, macrolides, penicillin, β-lactamase inhibitors, carbapenems, vancomycin, metronidazole
- lower risk: aminoglycosides, tetracyclines, trimethoprim, sulfonamides, rifampin
- Proton-pump inhibitors and histamine type 2 blockers
- Patient age (increased risk with age of the patient)
- hospitalization, Abdominal surgery,
Nasogastric tube
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-
Clinical manifestations
- ranging from an asymptomatic carriage to fulminant disease with toxic megacolon
- Symptoms of CDI may begin during antibiotic therapy or 5 to 10 days following antibiotic therapy
- Rarely, symptoms present as late as 10 weeks after cessation of antibiotic therapy
Diarrhea
- watery diarrhea: cardinal symptom (may be associated with mucus or occult blood
- Bloody stools are not an expected manifestation of infection with C. difficile
- lower abdominal pain and cramping
- low-grade fever (about 15 percent of cases; temperature >38.5°C is a sign of severe C. difficile–associated diarrhea)
- nausea, anorexia, leukocytosis (average white blood cell count of 15G/L)
Fulminant colitis
- diarrhea, lower quadrant or diffuse abdominal pain
- abdominal distention, fever, hypovolemia
- lactic acidosis, hypoalbuminemia, elevated creatinine
- marked leukocytosis (up to 40,000 white blood cells/microL or higher)
Complications
- hypotension, sepsis, renal failure
- toxic megacolon: severe systemic toxicity together with radiographic evidence of colonic dilatation (>7 cm in its greatest diameter)
- bowel perforation with peritonitis
Recurrent disease
Risk factors
- age >65 years
- Any prior episodes of C. difficile infection
- severe underlying medical disorders
- need for ongoing therapy with antibiotics during treatment for CDI
- Proton-pump inhibitor use
- Prolonged or recent stay in health care facility
Diagnosis
- diarrhea (more than three watery, loose or unformed stools within ≤24 hours) +
- diagnostic test (usually of a stool specimen) that detects the presence of either the C. difficile organism or
its toxin genes or
C. difficile toxin using an enzyme immunoassay or cell cytotoxin assay
- detection of Clostridium difficile and/or toxins
without
clinical symptoms does not meet criteria for Clostridium difficile infection
Treatment
- nonsevere Clostridium difficile-associated diarrhea
Metronidazole, 500 mg orally three times daily or 250 mg four times daily for 10 to 14 days
alternative:
Vancomycin, 125 mg orally four times daily for 10 to 14 days
- severe, complicated or fulminant
Vancomycin 500 mg 500 mg four times daily × 10-14 days
PLUS
Metronidazole 500 mg 500 mg every eight hours × 10-14 days
- first recurrence
Same as primary infection based on severity of disease
Prevention
- Prevention of C. difficile transmission to the patient:
hand hygiene: not effective
wearing gloves and gowns when handling the body substances of patients
Isolation of patients
using bleach solution for cleaning the rooms of patients with CDI
- Reduction of the likelihood of CDI developing in the event that a patient encounters C. difficile or its spores
avoidance of unjustified antibiotic use
probiotics: efficacy not proven
-
Rotavirus
Epidemiology
- fecal-oral route, contaminated water
- important cause of viral gastroenteritis worldwide
- Rotavirus is the most common cause of severe dehydrating diarrhea leading to the hospitalization of infants and children
- In temperate climates rotavirus infection peaks during the cooler months
- Viral shedding in stool: approximately 10 days
Clinical manifestations
- Incubation period less than 48 hours
- infection occurs most frequently among children but also occurs in adults.
- Immunocompromised hosts are more likely to develop a severe and protracted infection
- Laboratory findings are usually normal
- Diarrheal stools are usually watery and may be yellow without blood
Children
Typical symptoms: vomiting, nonbloody diarrhea and fever
The illness starts with a fever, vomiting: 2-3 days, then watery diarrhea: 4-5 days
Adults
typically mild and generally occurs among household members of affected children
outbreaks of gastroenteritis in colleges and nursing homes
clinical manifestations in adults are similar to those in children but are usually less severe
Severe diarrhea with hypovolemia among adults has been described
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Complications
dehydratation, necrotizing enterocolitis, seizures
aspiration pneumonia, seizures and encephalopathy, intussusception
Diagnosis
- Rotavirus gastroenteritis is not clearly distinguished from acute gastroenteritis
- prolonged diarrhea, in complicated cases, in immunocompromised hosts, when alternative diagnoses are considered, or when epidemiologic or infection control data are needed, it may be desirable to establish rotavirus as the etiologic agent.
- immune-based assays (such as enzyme-linked immunosorbent assay [ELISA] and latex agglutination testing) and nucleic acid testing, such as polymerase chain reaction (PCR)
- ELISA and latex agglutination are the most commonly used assays, PCR is the most sensitive
Treatment
The infection i usually self-limited and is treated with supportive measures.
No specific antiviral agents are available.
rehydration and supportive care
vaccines for infants
- RotaTeq (RV5)
Pentavalent human-bovine rotavirus reassortant vaccine
- Rotarix (RV1)
Attenuated human rotavirus vaccine
Norovirus
Epidemiology
- the most common cause of gastroenteritis in adults and children
- more than 50% (up to 90%) adults are seropositive
- transmission is more frequent in winter months
- immunity is not long lasting, and reinfection can occur
- fecal-oral route
- consumption of contaminated food and water
- incubation period is generally 24 to 48 hours (range 12 to 72 hours)
- virions ares shed with stool over 24-48 hours (rarely beyond 72 hours) after the onset of vomiting or diarrhea
- longer (weeks): under immunosuppression
- inoculum: <100 virions
- nosocomial transmission is common
- outbreaks (hospitals, nursing homes, cruise ships, schools)
- secondary infections, contamination of surfaces
Clinical manifestations
- asymptomatic infection
- mild illness with fever and watery diarrhea
- more severe illness with fever, vomiting, headache, and constitutional symptoms
- the onset is typically abrupt
- vomiting and diarrhea, although either can be present alone
- If diarrhea is present, it is generally moderate (approximately four to eight stools over a period of 24 hours).
- Stools are characteristically nonbloody, lack mucous, and may be loose to watery; fecal leukocytes are not seen.
- fever, myalgia, illness lasts for 48-72 hours
- Severe manifestations:
observed among children <12 months, older adults, and among patients with underlying disease who acquire infection during nosocomial outbreaks.
In such patients, fever is more common and the disease may last several days longer than in healthy individuals.
Diagnosis
typically: outbreak, in more than 50% patients vomit, incubation period 24-48 hours, the disease lasted 12-60 hours, no bacterial pathogen has been detercted
no leukocytes in stool
Immunoassays, PCR
Diarrhoea
- outbreaks of gastroenteritis (e.g. Norovirus, Rotavirus, STEC)
- foodborne diseases (e.g. Salmonella, Campylobacter, Listeria)
- nosocomial infections (e.g. C. difficile)
Clinical syndromes
Acute watery diarrhea
- Most bacterial and nonbacterial enteric pathogens
- Common causes: rotavirus in infants, ETEC, Norovirus. Enteric adenoviruses 40 and 41, V. cholerae, enterotoxin of C. perfringens
- vomiting, fever, loss of apetite
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-
Persistent diarrhea
- loose stools, with mucus and without blood
- diarrhea lasting more than 2 weeks
- In some cases, persistent diarrhea is associated with infection with enteroaggregative E. coli or parasitic infections such as C. hominis/parvum, Cystoisospora belli, or C. cayetanensis
- many cases of persistent diarrhea are triggered by a previous episode of acute gastroenteritis, and diarrhea is perpetuated by an inability to restore normal resorptive capacity after intestinal injury.
- local infection of the alimentary tract in immunocompromised host
- persistent diarrhea should raise suspicion of underlying illnesses (e.g. HIV infection)
Acute vomiting
- nausea / vomiting
- local infection (Norovirus) or
- bacterial food poisoning (ingestion of preformed toxins elaborated outside the host): short incubation period (1-6 hours), duration less than 12 hours; Toxin-producing staphylococci, B. cereus (the emetic form, mediated by a staphylococcal type of neurotoxin) or a longer incubation period of 8 to 16 hours (the diarrheal form, mediated by an enterotoxin resembling E. coli heat-labile toxin)
Enteric fever
- febrile illness that follows systemic spread of S. enterica after local invasion of the gut
- hepatosplenomegaly, abdominal pain, and neuropsychiatric symptoms
- persistant fever, diarrhea or constipation
- Salmonella typhi, Salmonella paratyphi A, B, C
- gastroeneteritis: diarrhea and/or vomiting
- diarrhea: 3 or more loose stools in 24 hours
acute: <14 days, persistent: 14 days or longer
- tenesmus: feeling of constantly needing to pass stools, despite an empty colon
- Foodborne illness (foodborne disease/food poisoning) illness resulting from the food spoilage of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food, as well as chemical or natural toxins such as poisonous mushrooms and various species of beans that have not been boiled for at least 10 minutes.