Understanding and Managing Gastrointestinal Tract Infections: A Complete Exploration of Causes, Signs, Prognosis, Remedy, and Prevention Methods

Understanding and Managing Gastrointestinal Tract Infections: A Complete Exploration of Causes, Signs, Prognosis, Remedy, and Prevention Methods

 

INTRODUCTION

Infections with quite a lot of brokers can happen in any a part of

the gastrointestinal (GI) tract from the mouth to the anal

canal. Infections can vary in severity from self-limited to life-

threatening, notably if an infection spreads from the intestine to

different components of the physique. Infections are usually brought on by the

ingestion of exogenous pathogens in adequate portions to

evade host defenses after which trigger illness by multiplication,

toxin manufacturing, or invasion via the GI mucosa to achieve

the bloodstream and different tissues. In different instances, members of

the conventional flora of the GI tract may cause illness.

ESOPHAGITIS

Definition

Esophagitis is an inflammatory course of that may injury the

esophagus.

Pathophysiology

Irritation brought on by an infection, usually by fungi equivalent to

Candida or viruses equivalent to herpes simplex virus, causes the

signs of esophagitis. Most instances happen in immunocom-

promised sufferers, particularly these with decreased cell-mediated

immunity. The extent of harm to the esophagus is often

associated to the severity of signs.

Scientific Manifestations

Odynophagia (ache on swallowing) and dysphagia (issue in

swallowing) are the important thing scientific manifestations of esophagitis.

Pathogens

Candida is the most typical etiology, notably amongst

human immunodeficiency virus (HIV)-infected sufferers and

different immunocompromised hosts (Determine 73–1). Much less frequent

pathogens embrace herpesviruses equivalent to cytomegalovirus and

herpes simplex virus. Noninfectious causes additionally happen, equivalent to

acid reflux disorder from the abdomen and medication-induced illness

(e.g., doxycycline).

Prognosis

Prognosis could also be empiric after a trial of fluconazole leads to

enchancment for presumed Candida esophagitis. If an empiric

course of fluconazole doesn’t work, then endoscopy for visu-

alization and biopsy could possibly be useful, notably in immu-

nocompromised hosts. Biopsy samples ought to be analyzed by

utilizing pathologic and microbiologic assessments.

Remedy

In a typical affected person (e.g., HIV-infected affected person) presenting with

odynophagia and retrosternal ache, an empiric prognosis of

esophageal candidiasis is made and fluconazole remedy insti-

tuted. If there isn’t a impact on signs and if Candida resistance

is just not suspected, then additional diagnostics as outlined earlier could

establish a selected organism that could possibly be focused for therapy.

Prevention

One possibility to forestall recurrent esophageal candidiasis is through the use of

fluconazole prophylaxis. Nonetheless, this isn’t usually suggested

given the excessive threat of choosing for fluconazole-resistant Candida.

Immune restoration in HIV-infected sufferers could lower the

incidence of esophageal and oropharyngeal candidiasis.

GASTRITIS

Definition

Gastritis refers to irritation of the mucosa of the abdomen.

It might be erosive or nonerosive, relying on histologic and

endoscopic findings. A break within the gastric and adjoining duode-

nal mucosa defines peptic ulcer illness.

Pathophysiology

The mechanism by which one of many important pathogens, Helico-

bacter pylori, causes peptic ulcer illness has been largely elu-

cidated. Following attachment to the gastric mucosa, H. pylori

causes direct mucosal injury by the mix of ammonia

manufacturing (from the motion of the organism’s urease on urea)

and the host inflammatory response. The flexibility of the organ-

ism to outlive is enhanced by the neutralization of the abdomen’s

acid by the ammonia produced.

Scientific Manifestations

Sufferers with gastritis usually complain of dyspepsia (epigas-

tric ache, burning), nausea, and vomiting. Within the case of peptic

ulcer illness, epigastric ache is the first symptom. Some

sufferers could report alleviation of ache with meals, notably

these with duodenal ulcers. Gastrointestinal bleeding is a com-

plication of peptic ulcer illness. Some sufferers with gastritis

could also be asymptomatic.

Pathogens

Infectious and noninfectious etiologies are attainable. Amongst

infectious causes, H. pylori is a very powerful. Viruses such

as cytomegalovirus and fungi equivalent to Mucor could not often trigger

ulcer illness as effectively, notably amongst immunocompromised

sufferers. Following ingestion of uncooked fish, larvae of Anisakis

species could change into embedded within the gastric mucosa and

trigger extreme belly ache. Mycobacteria (tuberculosis and

nontuberculosis mycobacteria), Giardia, and Strongyloides could

additionally trigger gastritis. Noninfectious causes equivalent to alcohol and

medicines (e.g., nonsteroidal anti-inflammatory medicine) are

additionally implicated.

Prognosis

Higher endoscopy with gastric biopsy is the definitive diagnostic

technique. If irregular findings are detected, pathologic evaluation

and additional directed testing could also be carried out. For probably the most

frequent infectious explanation for peptic ulcer illness, H. pylori-

related ulcers may be confirmed utilizing a urease check on the

biopsy specimen or utilizing noninvasive assessments such because the urea

breath check or stool antigen check.

Remedy

Remedy is directed on the underlying pathogen, taking the

host immune standing into consideration. For H. pylori, combina-

tion remedy with two antibiotics, equivalent to ampicillin and clar-

ithromycin, plus a proton pump inhibitor, equivalent to omeprazole,

or bismuth is used with various success.

DIARRHEA (GASTROENTERITIS,

ENTEROCOLITIS)

Definition

It’s helpful to think about diarrhea as acute (lasting <2 weeks) or

continual (persisting >4 weeks). We are going to give attention to acute diarrhea

on this chapter as a result of a lot of the etiologies are infectious in

nature. We will additional categorize acute diarrhea as noninflam-

matory (watery, nonbloody) or inflammatory (bloody). Bloody

diarrhea is often known as dysentery. For instance, bloody

diarrhea brought on by Shigella is usually known as bacillary dysentery.

Desk 73–1 describes the vital options of watery and

bloody diarrhea. Desk 73–2 lists the vital organisms that

trigger both watery or bloody diarrhea.

Diarrhea have to be calibrated in opposition to the affected person’s regular

bowel actions however is normally thought-about to be better than

three to 5 bowel actions per day. Many of the infectious

brokers that trigger diarrhea act on the small gut (the place the

majority of fluid usually will get absorbed) or the colon.

Acute diarrhea is quite common. There are roughly

179 million instances every year in america. Essentially the most

frequent explanation for acute diarrhea in america is norovi-

rus. It’s an particularly distinguished explanation for outbreaks of diarrhea.

The commonest explanation for deadly diarrhea is hospital-associated

Clostridium difficile.

Pathophysiology

Pathogens or their related toxins disrupt the conventional absorption

and secretory processes within the small intestines. Acute diarrhea is

normally brought on by preformed exotoxins in meals or by the infectious

brokers within the intestinal tract (through both enterotoxin and cytotoxin

manufacturing or mucosal invasion). Pathogens that produce pre-

shaped exotoxins embrace Staphylococcus aureus, Bacillus cereus,

and Clostridium perfringens. Different pathogens that trigger nonin-

flammatory acute diarrhea by enterotoxin manufacturing embrace

enterotoxigenic Escherichia coli (ETEC) and Vibrio cholerae.

Chapter 7 describes the mechanism of motion of those toxins.

Pathogens that trigger acute inflammatory diarrhea embrace

Salmonella, Shigella, Campylobacter (through mucosal invasion),

Shiga toxin-producing E. coli (STEC) equivalent to E. coli O157:H7,

and C. difficile (through cytotoxin manufacturing). Antibiotic use pre-

disposes to pseudomembranous colitis brought on by C. difficile.

Chapter 18 offers extra info on these enteric

gram-negative rods, and Chapter 17 discusses C. difficile.

There are a number of host elements that predispose to diarrheal ill-

ness. Sufferers taking proton pump inhibitors are in danger as a result of

gastric acid ranges are decreased. Current journey to growing

nations and antibiotic therapy are additionally related to an

elevated incidence of diarrhea. Immunosuppressed sufferers

have extra frequent and extra extreme diarrheal sickness.

Scientific Manifestations

Desk 73–3 describes the scientific presentation brought on by

vital GI tract pathogens. Sufferers complain of diarrhea

accompanied by urgency, belly bloating, and cramping.

Within the case of acute inflammatory diarrhea, there’s additionally blood

or pus seen within the stool, and sufferers may be febrile. If vomiting

is a significant function of the scientific presentation, this means S.

aureus meals poisoning or viral gastroenteritis. If signs

start inside 6 hours after ingestion of suspected contaminated

meals, then preformed toxin of S. aureus or B. cereus ought to be

suspected. On bodily examination, sufferers may present

indicators of dehydration with tachycardia and orthostatic adjustments

in blood stress.

Youngsters contaminated with STEC usually have bloody diarrhea

and should progress to hemolytic–uremic syndrome (HUS).

HUS happens when Shiga toxin produced by STEC enters the

bloodstream. The signs of HUS embrace hemolytic anemia,

thrombocytopenia, and renal failure. Distorted purple blood cells

known as schistocytes may be seen in blood smears. Using cip-

rofloxacin will increase the danger of HUS. Ingestion of undercooked

hamburger or contaminated produce or contact with animals at

petting zoos predisposes to illness brought on by STEC.

Pathogens

Most instances of delicate, acute watery diarrhea of brief period are

brought on by viruses. These embrace norovirus, rotavirus, and fewer

generally, adenovirus and astrovirus. Outbreaks of norovirus

an infection generally happen in closed populations, equivalent to nurs-

ing properties, hospitals, cruise ships, and dormitories. Rotavirus

is a typical explanation for diarrhea in kids, however the incidence is

declining because of elevated use of the rotavirus vaccine.

A number of micro organism are additionally vital causes of watery, non-

bloody diarrhea. Vibrio cholerae causes extreme, life-threatening

watery diarrhea. ETEC is the most typical explanation for traveler’s

diarrhea, usually a gentle to average watery diarrhea. Listeria

monocytogenes is one other bacterial trigger.

Most instances of extreme diarrhea, nevertheless, are brought on by bac-

teria. Pathogens equivalent to Salmonella, Shigella, Campylobacter,

STEC, and C. difficile are implicated on this class. Within the

United States, Salmonella and Campylobacter are probably the most

frequent bacterial causes. Diarrhea brought on by these micro organism is

usually bloody.

Protozoa, equivalent to Giardia, Entamoeba histolytica, Crypto-

sporidium, Cyclospora, and microsporidia, are much less frequent

causes of diarrhea however are suspected in sure eventualities (e.g., in

returning vacationers or immunocompromised sufferers). Of those

protozoa, Giardia is the most typical explanation for diarrhea within the

United States. Giardiasis usually happens in younger kids in

day care, in males who’ve intercourse with males, and in hikers who

drink untreated ambient water. In HIV-infected sufferers with

very low CD4 counts, Cryptosporidium causes extended diar-

rhea and should trigger extraintestinal illness involving the biliary

and respiratory tracts. Entamoeba histolytica causes amebic

dysentery characterised by bloody diarrhea.

Prognosis

Prognosis is usually targeted on deciding who and when

to check (i.e., figuring out when a check consequence could doubtlessly

impression the end result). As a result of many causes of acute diarrhea

are self-limited, this is a vital concern. Generally, we search a

prognosis in instances of extreme watery diarrhea, in instances of bloody

diarrhea, if the affected person is febrile, or if the affected person is aged or

immunocompromised. Routine stool cultures will establish

Salmonella, Shigella, and Campylobacter. If diarrhea is bloody, a

particular tradition (e.g., MacConkey-sorbitol agar) is particularly set

as much as detect STEC. The idea for the particular tradition is that STEC

strains usually don’t ferment sorbitol. The definitive labora-

tory prognosis of an STEC pressure is made by both polymerase

chain response (PCR) check or immunoassay for the Shiga toxin.

Cultures for enterotoxigenic E. coli (ETEC) aren’t carried out

within the typical scientific laboratory.

As well as, if bloody diarrhea is related to antibiotic

use, laboratory assessments for the presence of the C. difficile toxin in

the stool ought to be carried out. Colonoscopy could reveal the charac-

teristic yellowish plaques seen in pseudomembranous colitis

(Determine 73–2).

Rotavirus an infection may be recognized by testing the stool for

rotaviral antigen or for rotavirus RNA utilizing a PCR assay. A PCR

check for norovirus RNA within the stool can be utilized to diagnose infec-

tion by that virus and is particularly helpful in outbreak conditions.

Sending stool samples for evaluation of ova and parasites (O&P)

is usually not cost-effective, besides in immunocompromised

sufferers, sufferers with a historical past of latest overseas journey, or when

diarrhea is related to group waterborne outbreaks.

Stools for O&P are normally despatched on 3 consecutive days provided that

some parasites solely intermittently shed eggs or cysts within the stoo

Remedy

An important therapy modality in diarrhea is hydration.

Oral rehydration resolution containing water, salt, and sugar has been

life-saving in lots of components of the world. Generally, for many instances

of community-acquired diarrhea, empiric therapy with antimi-

crobials is just not useful. Traveler’s diarrhea is usually handled with

bismuth subsalicylate (Pepto-Bismol) or loperamide (Imodium).

The drug of selection for delicate or average colitis induced

by C. difficile is metronidazole. Extreme infections brought on by

C. difficile ought to be handled with oral vancomycin. Extreme

instances of shigellosis (bacillary dysentery) ought to be handled with

ciprofloxacin. Extreme instances of Campylobacter an infection ought to

be handled with azithromycin. Listeria gastroenteritis doesn’t

require antibiotics in immunocompetent, nonpregnant sufferers.

There isn’t any antiviral drug out there for both norovirus or rota-

virus. Giardia an infection ought to be handled with tinidazole.

Probiotics have little worth within the therapy of diarrhea.

Prevention

Many of the preventative methods are directed at vacationers to

growing nations. They’re suggested to keep away from doubtlessly con-

taminated water sources in addition to contemporary fruit and greens if

not washed in boiled water. One present strategy is to offer

the traveler with a provide of antimicrobials, equivalent to ciprofloxacin,

to be taken within the occasion of a diarrheal episode. Probiotics could also be

helpful to forestall antibiotic-associated colitis brought on by C. difficile.

There are two rotavirus vaccines out there (see Chapter 40).

Each comprise reside virus and are given orally. One is a reside, attenu-

ated vaccine (Rotarix), which incorporates the one commonest

rotavirus serotype (G1) inflicting illness in america.

The opposite is a reside reassortant vaccine (Rotateq), which incorporates

5 rotavirus strains. An elevated threat of intussusception has

been reported with each vaccines. Sufferers with a historical past of

intussusception shouldn’t obtain both vaccine.

APPENDICITIS

Definition

Appendicitis is irritation of the vestigial vermiform appen-

dix. It is among the commonest causes of acute stomach

requiring surgical exploration.

Pathophysiology

Obstruction of the appendix by one in every of quite a lot of causes (e.g.,

fecaliths, an infection equivalent to parasites, tumor) results in a rise

in luminal and intramural stress. Bacterial overgrowth is

accompanied by irritation. If there’s necrosis, perforation

adopted by diffuse peritonitis brought on by micro organism of the conventional

colonic flora (e.g., E. coli and Bacteroides) could happen.

Scientific Manifestations

Scientific manifestations embrace belly ache (particularly peri-

umbilical ache migrating to the best decrease quadrant), anorexia,

nausea, and vomiting. Low-grade fever and delicate leukocytosis

could also be current. Preliminary signs could also be missed as a result of they

could also be nonspecific (e.g., indigestion). A normal belly

computed tomography (CT) scan with distinction is usually used

when appendicitis is suspected.

Pathogens

Early in the middle of the illness, the predominant organisms

are anaerobic. In late illness, combined organisms predominate.

Escherichia coli, Peptostreptococcus, Bacteroides fragilis, and

Pseudomonas are generally remoted. Yersinia, Campylobacter,

and Salmonella may cause an acute ileitis and mesenteric adeni-

tis that may mimic appendicitis.

Prognosis

Scientific manifestations mixed with imaging, utilizing both CT

scan or ultrasonography, are usually used to decide

as as to whether a affected person ought to be taken to the working room.

Remedy

Surgical procedure is the definitive therapy for appendicitis, normally in

live performance with perioperative antibiotics. Laparoscopic appendec-

tomy is most popular to open appendectomy, because the laparoscopic

strategy has a decreased threat of surgical wound website infections, a

decreased threat of bowel obstruction, and a quicker restoration time. A

course of antibiotics alone (with out surgical procedure) is usually used,

however there’s an elevated threat of recurrent appendicitis.

Perforation of the diverticulum with consequent abscess forma-

tion or peritonitis could happen.

Pathophysiology

Colonic diverticula could happen following years of a eating regimen poor

in fiber.

Scientific Manifestations

There’s a vary of signs relying on the diploma of perfora-

tion. Sufferers normally current with uninteresting, aching, left decrease quadrant

belly ache. That is usually accompanied by a low-grade fever,

leukocytosis, nausea, and vomiting. Diarrhea or constipation could

be current. If perforation happens, sufferers can current with gen-

eralized peritoneal indicators with diffuse belly ache and shock.

Pathogens

Bowel flora equivalent to anaerobes, that’s, B. fragilis, and people within the

Enterobacteriaceae household, equivalent to E. coli, are usually concerned.

Prognosis

Belly CT will present colonic diverticula and related wall

thickening, fats infiltration, abscesses, and extraluminal air or

distinction medium.

Remedy

Oral antibiotics with wonderful anaerobic exercise (e.g., amoxicillin

with clavulanate or a mix of ciprofloxacin plus metro-

nidazole) are utilized in delicate instances. In additional severe instances requiring

hospitalization, intravenous fluids and antibiotics are given with

bowel relaxation as wanted. If there’s an related belly abscess

or indicators of peritonitis, surgical analysis have to be undertaken.

Prevention

Prevention entails growing the quantity of fiber within the eating regimen.

ENTERIC FEVER SUCH AS TYPHOID

FEVER

Definition

Enteric fever is a scientific syndrome comprised of constitutional

signs, equivalent to fever and headache, and nausea, vomiting, and

belly ache. Though enteric fever may be brought on by a number of

Salmonella species, “typhoid fever” refers to enteric fever brought on by

Salmonella typhi. S. typhi is often known as Salmonella enterica sero-

sort Typhi. Typhoid fever is a big world well being downside.

Pathophysiology

Following the consumption of contaminated meals, Salmonella

micro organism enter via the intestinal mucosal epithelium by

transcytosis. The microbes then replicate within the macrophages of

Peyer patches, mesenteric lymph nodes, and spleen. Bacteremia

then happens with dissemination to lungs, gallbladder, kidneys,

or central nervous system.

People are the one reservoir for S. typhi, so contamination

of meals or water by human feces ought to be suspected.

Scientific Manifestations

A prodromal part is characterised by constitutional signs

equivalent to malaise, along with belly ache, constipation,

and headache. Fever will increase over the subsequent a number of days. Dur-

ing the second week of illness, a typical transient rash of pink

maculopapular lesions (rose spots) could also be seen. Splenomegaly

happens extra generally than hepatomegaly, however each could

happen. Relative bradycardia and leukopenia are sometimes noticed.

Diarrhea is unusual.

The continual service state happens in roughly 3% of

sufferers with typhoid fever. The organisms usually reside in

the gallbladder and are excreted within the stool, serving as a supply

of an infection for others.

Pathogens

Salmonella typhi and different Salmonella species, equivalent to Salmo-

nella paratyphi A and S. paratyphi B, trigger typhoid fever.

Prognosis

A historical past of journey to endemic areas, along with a compat-

ible scientific presentation, is usually used initially. Any fever in a

returning traveler ought to immediate blood cultures and a scientific

suspicion for enteric fever. Early within the illness, blood cultures

are usually constructive and stool cultures are sometimes destructive. Later

within the illness and within the service state, stool cultures are posi-

tive and blood cultures are destructive. Stool cultures are constructive

at this stage as a result of bile from an contaminated gallbladder carries

organisms into the stool.

Remedy

Oral or intravenous ciprofloxacin is usually used. Intravenous cef-

triaxone is one other efficient therapy modality. Ciprofloxacin

for 4 weeks will also be used to eradicate the service state. Cho-

lecystectomy ought to be thought-about for these continual carriers

who don’t reply to antimicrobial remedy.

Prevention

Hygienic measures to guard the meals and water provide from

human fecal contamination are an vital public well being

intervention. Immunization could not all the time be efficient however

may be thought-about in epidemic outbreaks, for vacationers to

endemic nations, and for family contacts of typhoid

carriers.

Two vaccines in opposition to typhoid fever can be found within the

United States, each offering roughly 50% to 80% pro-

tection. The vaccine containing the Vi capsular polysaccha-

journey of S. typhi has the benefit of being administered as soon as

intramuscularly. The opposite vaccine incorporates reside attenuated

S. typhi organisms and is run orally. It has the advan-

tage of stimulating intestine immunity (IgA) thereby interrupting

transmission.