Page 977 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

708 PART 5: Infectious Disorders

Especially in a patient with community-onset diarrhea, the identifica- TABLE 76-4 Recommended Antimicrobial Regimens for Patients Hospitalized
tion of fecal leukocytes on direct observation should warrant a search with Bacterial Diarrhea
for bacterial pathogens that cause inflammatory diarrhea, including
E coli, C jejuni, Salmonella, and Shigella species. Stool culture can be Recommended Treatment
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particularly useful in distinguishing the bacterial pathogens that are com- Pathogen Regimen Notes
monly associated with these food-borne gastroenteritis. Selective media, Campylobacter jejuni Azithromycin or Fluoroquinolone resistance
such as MacConkey, desoxycholate, and Salmonella-Shigella agar, are ciprofloxacin increasing in some regions
employed in the microbiology lab to enhance the ability to detect these Escherichia coli O157:H7 No antimicrobial therapy Antimicrobials may increase the
pathogens. It is useful to identify particular epidemiologic concerns to the
microbiology lab so that the appropriate media can be employed. advised risk of hemolytic uremic syndrome
The examination of stool for the presence of ova and parasites is of Salmonella species Ciprofloxacin or azithromycin Treat only if symptoms are severe or

limited utility among patients in the ICU. First and foremost, the clini- the patient is immunocompromised
cal syndromes caused by infection with these organisms tend not to be Shigella species Ciprofloxacin or azithromycin
so serious as to require admission to the ICU. Moreover, the incidence Traveler diarrhea Fluoroquinolone Use of antimotility agents is
of parasitic infections in ICU patients is so low as to make the positive appropriate
predictive value of the stool ova and parasite examination vanishingly
small. In this context, even a positive finding on stool ova and parasite Vibrio cholerae Ciprofloxacin, doxycycline, Rehydration is cornerstone
examination is more likely to represent a false-positive result than it is or azithromycin of therapy
to represent actual infection. Many hospital-based clinical laboratories Yersinia enterocolitica Doxycycline + aminogly-
have gone so far as to not accept stool ova and parasite specimens from coside or fluoroquinolone
patients who have been hospitalized for more than 48 or 72 hours.
The role of endoscopy in the evaluation of infectious diarrhea in the
ICU is limited. While biopsy may detect the presence of specific patho-
gens such as Entamoeba histolytica, the relatively low incidence of these hospital costs attributable to CDI in the United States were $3.2 billion
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infections in this population makes this the diagnostic procedure of per year for the years 2000 to 2002.
last resort. Lower GI endoscopy will not help discriminate or diagnose The epidemiology of CDI has changed dramatically in the past
infection with common bacterial pathogens such as E coli or C jejuni. As decade. During this time period, CDI has been noted to be more fre-
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discussed later, sigmoidoscopy and colonoscopy can be helpful in the quent, severe, more refractory to treatment, and more likely to relapse.
detection and diagnosis of colitis caused by C difficile infection. A study of US acute care hospital discharge data in 2001 revealed a sub-
■ TREATMENT from the hospital with the diagnosis of “intestinal infection due to
stantial increase in the number and proportion of patients discharged
The foremost objective in the care of the patient with infectious diar- Clostridium difficile,” with the largest increase seen among patients aged
65 year or more. The increase in the incidence and severity of CDI
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rhea is to restore the patient to a normal fluid and electrolyte balance is likely due to the spread of the BI/NAP1/027 strain, which has been
as rapidly as possible. While oral rehydration solutions, such as that associated with fluoroquinolone use. This particular strain produces
recommended by the World Health Organization, have proven safe and toxins A and B, and a binary toxin. It also has a genetic deletion in the
effective in settings in which intravenous therapy is either impracti- tcdC gene, which typically acts as a negative regulator of the produc-
cal or unavailable, most patients with diarrhea in the ICU will require tion of toxins A and B. A Canadian study found infection with this
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parenteral replenishment. Effective regimens include lactated Ringer specific strain led to a doubling of the 30-day mortality compared to
solution and normal saline with electrolyte supplementation. The use of patients infected with other C difficile strain types. 31,33 This strain not
large volumes of 5% dextrose and water for these patients may precipi- only appears to be more virulent but also resistant to fluoroquinolones.
tate dangerous hyponatremia. No matter the regimen selected, serum It is believed that increased fluoroquinolone use in North American may
chemistry analyses should be performed frequently to ensure adequacy partially explain the dissemination of this strain. There also appears to
of electrolyte replacement. be disease occurring in populations who were previously considered to
In general, empirical antimicrobial therapy for infectious diarrhea be at low risk of CDI including healthy peripartum women and persons
not associated with C difficile should be avoided. Indiscriminant anti- living in the community without prior health care contact. 28
biotic use for this indication exposes the patient to needless toxicity, The route of transmission for C difficile is primary person to person by
may precipitate the emergence of resistant organisms as a cause of fecal-oral spread. The hands of health care workers that are transiently
systemic infection, can worsen the course of some infection (as in the contaminated with C difficile spores are one source of transmission
case of E coli serotype O157:H7), and might predispose the patient and another means of spread is through environmental contamination.
to prolonged carriage with the offending pathogen. However, once Because the spores of C difficile are difficult to eradicate, spread via inad-
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a specific pathogen has been identified, therapy can be directed by equately cleaned fomites can contribute to transmission. Asymptomatic
documented susceptibility information—or at least trends among colonization is likely another source of transmission. Studies have found
known or suspected pathogens. Pathogen-specific recommendations asymptomatic colonization in 7% to 26% among adult inpatients in
are listed in Table 76-4. acute care facilities and 5% to 7% among elderly patients in long-term
care facilities. 34,35 Other studies estimate in CDI endemic areas the
CLOSTRIDIUM DIFFICILE INFECTION asymptomatic colonization may be higher, in the range of 20% to 50%. 28
■ EPIDEMIOLOGY suppression, manipulation of the gastrointestinal tract, and exposure
Risk factors for CDI include advanced age, hospitalization, immune
As was already noted, Clostridium difficile is the single most common to antibiotics. The antibiotics most frequently associated with CDI are
cause of infectious diarrhea among all hospitalized patients, includ- clindamycin, expanded-spectrum penicillins, fluoroquinolones, and
ing those in the ICU. It is estimated now that C difficile is the primary cephalosporins, but it is important to remember almost any antimi-
pathogen in 20% to 30% of cases of nosocomial antibiotic-associated crobial agent can induce disease. Olson and colleagues reported that
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diarrhea. Hospital costs for patients who acquire C difficile infection 96% of patients with symptomatic CDI had antimicrobial exposure in
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(CDI) are more than 50% higher than for those without infection and the last 14 days before the onset of disease and all patients with CDI
an episode of C difficile colitis prolongs the average length of stay for had received antibiotics within three previous months. The observed
infected patients by nearly 4 days. It was estimated that annul excess association between some antineoplastic chemotherapy agents and CDI
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