Page 974 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 76: Gastrointestinal Infections and Clostridium Difficile 705

of this epidemiologic phenomenon needs to be incorporated into the which GI pathogens may take a toll among critically ill patients. The
approach to therapy for such patients. etiologic relationship between the presence of Helicobacter pylori and
Herpes simplex virus (HSV) is another frequent cause of esophagitis ulcerative disease of the upper GI tract, and particularly the duodenum
and is the most common serious viral infection of the upper GI tract and stomach, has been firmly established. Importantly, treatment of
among patients in the ICU. For the most part, HSV-1 is more likely to H pylori infection with combinations of antimicrobial agents and inhibi-
cause esophagitis than is HSV-2, which is more typically associated with tors of gastric acidity will eradicate H pylori infection, and in so doing
genital infections. Less frequently, other viruses, including cytomegalo- promote the resolution of peptic ulcer disease. Antibiotics employed
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virus (CMV), can cause esophageal ulceration. For patients with CMV for this purpose are active against H pylori and include macrolides,
disease, lesions may extend throughout the length of the GI tract. metronidazole, and β-lactam agents. Acid suppressive agents given
■ DIAGNOSIS concurrently include sucralfate, H -receptor blockers, and proton-pump
2
inhibitors.
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Thorough physical examination is not only essential to the diagnosis of Given these findings and a growing clinical experience with this
esophagitis, but may offer preliminary clues as to the causative pathogen. strategy, it is not surprising that a link between H pylori infection and
Both yeast and viral pathogens infecting the esophagus can produce tell- the stress-induced gastritis that affects patients in the ICU has been
tale lesions in the oral cavity, where they will be easily detected on routine proposed. Thus far, the results concerning this possible association
physical examination. Although present in fewer than one-third of all remain inconclusive. In a prospective, single-institution study of patients
patients with HSV esophagitis, oral or labial herpetic ulcers should not be admitted to a medical/surgical ICU, half of all patients were positive
missed in the physical examination of the critically ill patient with unex- for H pylori by urea breath test. After adjusting for other risk factors,
plained fever. Similarly, an adherent white coating to the lateral aspects H pylori infection was the only clinical factor significantly associated with
6
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of the tongue, which when scraped away reveals patches of inflamma- subsequent major mucosal injury. However, the same investigators
tion, should point to Candida albicans as the cause of a suspected case of observed that the prevalence of H pylori infection among ICU patients
esophagitis. Despite the utility of such findings, it is equally important to declined to 8% by the third day of admission, and to 0% by 1 week,
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recognize that esophagitis most often occurs in the absence of such clues. owing to intercurrent antibiotic exposure. In another study by Robert
Nevertheless, to miss these clinical findings, when present, is to miss a and others, 1776 intensive care unit patients were screened for H pylori
critical opportunity for early diagnosis and intervention. by stool antigen testing and only 6.3% of patients were found to be posi-
Upper GI endoscopy can be a useful tool to confirm the pathologic tive. Of these patients who tested positive for H pylori the authors did
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and microbiologic diagnosis of esophagitis. Unfortunately, even when not find any additional risk of gastrointestinal bleeding. Based on these
visualized through the endoscope, the lesions of Candida and HSV conflicting results, there does not seem to be a role for routine screening
esophagitis may appear quite similar. Even the large shallow ulcers typi- for H pylori in all intensive care unit patients.
cal of CMV esophagitis may be mimicked by Candida or HSV. Because
of this lack of discriminatory power, it is advisable to proceed to confir-
matory biopsy. Brush specimens alone can be inadequate, especially as DIARRHEA
Candida species can be isolated as colonizers of the upper GI tract in up Diarrhea, the principal manifestation of intestinal infection among the
to 20% of asymptomatic individuals. Once obtained, tissue should be critically ill, affects approximately one-third of all patients admitted
7
sent for viral and fungal culture as well as for histopathologic examina- to the ICU. Patients in the ICU with diarrhea are especially vulner-
15
tion to confirm tissue invasion. able to the clinical sequelae of infection. For the critically ill patient,
■ THERAPY the dehydration that frequently accompanies severe diarrhea strains a
circulatory capacity already limited by impaired cardiac contractility
Under most circumstances, directed therapy for esophagitis should be and septic hemodynamics. Such individuals are at high risk for further
withheld until the causative organism has been identified. However, for systemic deterioration, often culminating in multisystem organ failure.
critically ill patients with suspected esophagitis in whom endoscopy is not In addition to life-threatening volume loss, diarrhea in the critically ill
practical and microbiologic diagnosis is not feasible, it is appropriate to patient can precipitate metabolic derangements including electrolyte
treat empirically for C albicans, based on the prevalence of this entity in imbalances and acidosis, further exacerbating the potential for cardiac
this population. For esophagitis when C albicans is known or suspected rhythm irritability. Finally, uncontrolled diarrhea in a severely ill immo-
to be the cause, the most effective treatment is fluconazole given intrave- bile patient can predispose to compromise of the protective barrier of
nously at a dose of 100 to 200 mg per day for 14 to 21 days. Itraconazole the skin. As such, the patient is rendered vulnerable to further infectious
and the newer agents, voriconazole and posaconazole, can be used as complications. Considering these dire clinical consequences, the prompt
alternatives to fluconazole. Studies have shown similar success rates of detection, microbiologic diagnosis, and treatment of infectious diarrhea
cure for echinocandins in comparison to fluconazole but higher rates of must be a high priority for clinicians in the ICU.
relapse among those patients receiving echinocandins. Because of higher The epidemiology of diarrheal illness among patients in the ICU is
cost and higher relapse rates, echinocandins should not be the first choice substantially different from that seen among less severely ill patients in
in the absence of detecting fluconazole-resistant pathogens or persistent the community. Such differences render most of the schemes used to
infection. For those infected with Candida species resistant to flucon- classify diarrhea in other settings somewhat less useful to the evaluation
azole, or for patients with persistent infection despite first-line therapy, of the critically ill patient. Infectious diarrhea acquired in the outpatient
echinocandins or amphotericin B can be used as salvage therapy. 8,9 setting is rarely sufficiently severe to warrant admission to the ICU.
For HSV esophagitis, the antiviral agent with which there is the most Therefore, infectious diarrhea among patients in the ICU is most often
clinical and published experience is acyclovir. Most patients in the ICU acquired in the hospital. As a result, the spectrum of clinical disease and
will require parenteral therapy—5 mg/kg intravenously every 8 hours for associated pathogens for the patient in the ICU tends to be less diverse
7 to 14 days. If the virus is resistant to acyclovir, intravenous foscarnet than that encountered in the community. In fact, the majority of all
can be substituted. cases of infectious diarrhea diagnosed in the ICU can be attributed to
a single pathogen, Clostridium difficile. For many of these patients, the
GASTRITIS differential diagnosis consists largely of noninfectious entities, such as
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diarrhea induced by hyperosmolar enteral feeding solutions. Norovirus
While the stomach is not typically considered an important site of infec- and related viral pathogens, the most common causes of endemic and
tion among hospitalized patients, the association between Helicobacter epidemic diarrhea in the outpatient setting, are rarely identified as the
pylori infection and gastric stress ulceration suggests another means by cause of diarrhea in critically ill patients. Similarly, while outbreaks

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