Escherichia coli (E coli) Infections Clinical Presentation

Acute bacterial meningitis

Newborns with E coli meningitis present with fever and failure to thrive or abnormal neurologic signs. Other findings in neonates include jaundice, decreased feeding, periods of apnea, and listlessness.

Patients younger than 1 month present with irritability, lethargy, vomiting, lack of appetite, and seizures.

Those older than 4 months have neck rigidity, tense fontanels, and fever.

Older children and adults with acute E coli meningitis may develop headache, vomiting, confusion, lethargy, seizures, and fever.

In rare instances, individuals from a community where Strongyloides is endemic or an individual who traveled through 1 of these regions may develop S stercoralis hyperinfection if infected with the parasite and given immunosuppression, specifically high dose steroids. This then leads to translocation across the gut barrier, causing an E coli bacteremia and potential seeding of the meninges.

Persons with a history of open CNS trauma may develop a contiguous infection from a surgical site infection. Because patients who have undergone neurosurgical procedures frequently have headaches, nuchal rigidity, and a decreased level of consciousness secondary to the surgery, it may be difficult to identify a concurrent active infection.

The differential diagnoses of acute E coli meningitis include bacterial meningitis (most common H influenza, N meningitidis, and S pneumoniae), viral meningitis, sepsis, seizure disorder, brain abscess, ruptured aneurysm, and neonatal tetanus.

Pneumonia

Patients with E coli pneumonia usually present with fever, shortness of breath, increased respiratory rate, increased respiratory secretions, and crackles upon auscultation.

Findings include bronchopneumonia on chest radiography, commonly in the lower lobes. If patient is limited to the supine position, pneumonia may present in the upper lobes (Right upper favored over L upper lobe). Many patients are intubated, have fever, an increased respiratory rate, and increased purulent respiratory secretions.

The differential diagnoses of E coli pneumonia include congestive heart failure, pulmonary embolism, other bacterial pneumonias, and viral pneumonias. Other pneumonias caused by gram-negative bacilli are difficult to distinguish clinically and require a sputum culture to identify a causative organism.

Intra-abdominal infections

Patients with E coli cholecystitis or cholangitis develop right upper quadrant (RUQ) pain, fever, and jaundice [Charcot’s Triad]. In severe cases, hypotension and confusion also develop [Raynaud’s Pentad].

Cholecystitis may be difficult to distinguish from cholangitis, however both may manifest with significant fever (>102*F), and cholangitis may be more severe with shaking chills (rigors), and cholangitis due to obstruction of the common bile duct could be complicated by hepatic abscess.

Amebic liver abscess, Echinococcus cyst, and Klebsiella and Enterococcus infections are difficult to distinguish clinically.

Patients with E coli intra-abdominal abscesses generally present as an abscess that is a combination of other enteric organisms to include potential anaerobic bacteria. Individuals may have low-grade fevers, but the clinical spectrum of presentations range from nonspecific abdominal examination findings to septic shock. If the infection is contained, the patient may not have peritonitis. Peritonitis manifests as diffuse abdominal pain with rebound tenderness on palpation and fever.

The differential diagnoses includes other intraabdominal infections including appendicitis, diverticulitis, septic thrombophlebitis, retroperitoneal hematoma.

Enteric infections

Patients with E coli traveler's diarrhea (ie, watery nonbloody diarrhea; caused by enterotoxigenic E coli [ETEC] or enteroaggregative E coli [EAggEC]) may appear to be dehydrated. Traveler's diarrhea is observed in young healthy travelers to tropical countries and is watery diarrhea without polymorphonuclear (PMN) leukocytes. The differential diagnoses of E coli traveler's diarrhea include rotavirus infection, Norwalk virus infection, Salmonella infection, and Campylobacter diarrhea.

Patients with E coli childhood diarrhea (ie, watery nonbloody diarrhea; caused by EAggEC, enteroadherent E coli [EAEC], or enteropathogenic E coli [EPEC]) may appear to be dehydrated. These infections produce a noninflammatory watery diarrhea observed especially in children. The differential diagnoses of E coli childhood diarrhea include Vibrio cholerae infection and rotavirus infection.

In May, June, and July, 2011 an outbreak of gastroenteritis caused by Shiga-toxin–producing E coli was seen in Germany. Most patients were adults, and 22% of the cases developed hemolytic–uremic syndrome. The outbreak strain was typed as an enteroaggregative Shiga-toxin–producing E coli O104:H4, producing extended-spectrum beta-lactamase. The consumption of sprouts was identified as the most likely vehicle of infection. This outbreak was different as it was caused by EAggEC that produced a Shiga toxin and it exemplifies the threat posed by foodborne pathogens with their propensity to cause large common-source outbreaks. ^{[6, 7]}

Patients with E coli dysentery (caused by enteroinvasive E coli [EIEC] or enterohemorrhagic E coli [EHEC]) have fever, bloody diarrhea, and dehydration. Intestinal mucosa produces a significant inflammatory response. Clinically, patients with E coli dysentery present with fever and have blood and PMN leukocytes in their stool. The differential diagnoses of E coli dysentery include shigellosis, typhoid fever, and amebic dysentery.

Patients with E coli hemolytic uremic syndrome (HUS) (caused by EHEC) have fever, bloody diarrhea, dehydration, hemolysis, thrombocytopenia, and uremia. The hemolysis may lead to deposition of the remnants of the red blood cells into the kidney, causing oxidative destruction, and potentially requiring dialysis. Symptoms of E coli HUS range may have nonbloody to bloody diarrhea, however generally have systemic findings due to the systemic cascade that occurs in the setting of bacterial toxin related hemolysis. This includes renal failure, microangiopathic hemolytic anemia, thrombocytopenia, and CNS manifestations. The differential diagnoses of E coli HUS include Shigella infections, Clostridium difficile enterocolitis, ulcerative colitis/Crohn disease, ischemic colitis, diverticulosis, and appendicitis.

Urinary tract infections

Acute E. coli cystitis manifests with dysuria, increased urinary frequency, urinary urgency, and rarely may present with a low grade fever. Less commonly, patients have may develop urinary tract infections secondary to other enteric organisms such as Klebsiella, Proteus mirabilis, or Enterococcus. Approximately 15% of cases are culture-negative; these are due to Chlamydia trachomatis, Ureaplasma urealyticum, or Mycoplasma hominis infection. Staphylococcus saprophyticus urinary tract infection is a rare infection observed in 5-10% of cases, especially in sexually active women, associated with alkaline pH and microscopic hematuria.

Patients with E coli pyelonephritis or complicated UTI present with localized flank or low back pain, high fever (>102°F), urinary frequency, and urgency. Due to the systemic nature of this more severe infection, other symptoms may include rigors, sweating, headache, nausea, and vomiting. Untreated or severe infections can be complicated by necrotizing intrarenal or perinephric abscess, which may manifest as a bulging flank mass or pyelonephritis that does not respond to antibiotics. Patients with diabetes or urinary tract obstruction also can develop bacteremia and septicemia.

**The differential diagnoses include psoas abscess appendicitis, ectopic pregnancy, and ruptured ovarian cyst.

Patients with E coli acute prostatitis or prostatic abscess have chills, sudden fever (>102°F), and perineal and back pain with a tender, swollen, indurated, and hot prostate. Acute prostatitis also manifests as dysuria, urgency, and frequent voiding. Some patients may have myalgia, urinary retention, malaise, and arthralgia. If the patient does not respond to antibiotics, consider prostatic abscess and confirm it with imaging studies. Treatment consists of open surgical or percutaneous drainage.

Patients with E coli prostatic abscess, which manifests as a complication of acute prostatitis, have a high fever despite adequate antimicrobial therapy and fluctuance of the prostate upon rectal examination.

The differential diagnoses of E coli acute prostatitis or prostatic abscess can include chronic bacterial prostatitis, which usually is asymptomatic; some patients may have frequency, dysuria, and nocturia with pain and discomfort in the perineal, suprapubic, penile, scrotal, or groin region. Also included are infected prostatic calculi, which can cause recurrent UTIs and should be surgically removed. Finally, nonbacterial prostatitis is also a differential diagnostic possibility and manifests as perineal, suprapubic scrotal, low back, or urethral tip pain.

Additionally, patients with E coli renal abscess present with fever, pleuritic chest pain secondary to diaphragmatic irritation, and flank pain, with or without a palpable abdominal mass. ^[6]

Acute bacterial meningitis

E coli is a common cause of meningitis in newborns and is associated most frequently with prematurity.

E coli meningitis can be acquired during birth or can develop secondarily after infection in another body site, such as in cases of omphalitis, upper respiratory tract infection, or infected circumcision wound.

In adults, E coli meningitis is not uncommon in those who have undergone multiple neurological procedures or who have had open CNS trauma.

Immunosuppressed patients receiving corticosteroid therapy and those with S stercoralis hyperinfection also are at risk for E coli meningitis.

Pneumonia

E coli pneumonia is often preceded by colonization of the upper respiratory tract (eg, nasopharynx), however this is rare in the general population and seen more in individuals with cystic fibrosis, intubation, or those with chronic aspiration.

Community-acquired E coli pneumonia has been reported in rare cases.

Intra-abdominal infections

Along with Enterococcus faecalis and Klebsiella species, E coli is one of the most common organisms associated with cholecystitis/cholangitis and intra-abdominal abscesses, as part of polymicrobial flora including anaerobes.

E coli cholecystitis/cholangitis manifests as the classic Charcot triad of fever, pain, and jaundice in 70% of cases. Fever is the most common finding (95%). RUQ pain and jaundice may be absent if no obstruction is present.

In late stages, hypotension, confusion, and renal failure are observed.

Liver abscess can develop as a complication of an E coli biliary tract infection.

The findings of E coli intra-abdominal abscesses are less conspicuous than those of diffuse peritonitis. The patient may have only low-grade fever, generalized malaise, and anorexia. In the postoperative patient who may have a distended and tender abdomen, clinical diagnosis of E coli intra-abdominal abscess may be difficult.

Enteric infections

Traveler's diarrhea usually occurs in persons from industrialized countries who visit tropical or subtropical regions and develop abdominal cramps and frequent explosive bowel movements 1-2 days after exposure to contaminated food or water.

E coli enterotoxin acts on the GI mucosa, leading to an outpouring of copious fluid from the small bowel.

The symptoms usually last 3-4 days and are self-limited.

Large fluid loss may result in dehydration.

EIEC infections are rare and manifest as bloody diarrheal stool containing PMN leukocytes. Patients usually have fever, abdominal cramping, and tenesmus lasting 5-7 days.

Childhood diarrhea is due to EPEC strains and usually occurs in underdeveloped countries or nursery outbreaks. The volume of diarrhea is less than that with ETEC strains, and no inflammatory cells are found in the diarrheal fluid. The child may experience fever, and diarrhea lasts longer than 2 weeks in some cases.

Infection with EHEC strains of the serotype 0157:H7 begins as watery diarrhea followed by grossly bloody stool without inflammatory PMN cells and results in HUS in 10% of cases, characterized by hemolysis, thrombocytopenia, uremia (possibly requiring dialysis), and death in some cases.

EAggEC and EAEC cause clinical illnesses that are not yet well characterized and are associated with persistent diarrhea in children.

Urinary tract infections

E coli is the leading cause of community-acquired and nosocomial UTI.

Females are predisposed to UTI because of their anatomy and changes in hormones during sexual maturation, pregnancy, and childbirth. Post-menopausal females are at high risk for urinary tract infections due to loss of protective vaginal bacteria that rely on estrogen for growth and thus decrease in the absence of significant estrogen production after menopause.

Young boys with posterior urethral valves are and elderly men with prostatic hypertrophy are predisposed to urinary tract infections due to obstructive nature of these disease processes leading to stasis of urine and potential for infection to develop.

Other risk factors for the development of UTIs include catheterization or mechanical manipulation leading to introduction of a foreign body that can become colonized easier or potential introduce bacteria upon placement. Other mechanisms that cause obstruction can lead to urine stasis and increase risk for the subsequent fluid to become infected. Diabetes may increase risk through glycosuria thereby providing nutrients the bacteria need to grow faster and develop an infection.

Patients with E coli UTI present with a wide spectrum of symptoms, ranging from asymptomatic cystitis to pyelonephritis/perinephric abscess.

Uncomplicated E coli acute cystitis may manifest as suprapubic pain, dysuria, and increased urinary frequency. Fever may be present but is suggestive of a developing complicated UTI or pyelonephritis.

Acute pyelonephritis generally manifests with nausea, fever, and costovertebral tenderness.

Acute prostatitis manifests as a sudden onset of fever and chills with perineal pain, and the individual may have concurrent low back pain.

Perinephric abscess may manifest as a bulging flank mass (citation, Medscape; inferior pole). GI symptoms such as nausea and vomiting are more likely in elderly persons. Patients with bacteremia secondary to an obstructed urinary catheter may present with decreased urine output.

Prostatic abscess can occur as a complication of acute prostatitis, notably in patients with diabetes mellitus, and should be considered in patients with acute prostatitis or UTI that is not improving with adequate antimicrobial therapy.

Other infections

E coli bacteremia can lead to septic shock, manifesting as hypotension and fever (in some cases, with hypothermia rather than fever). It may be complicated by a multisystem organ failure to include acute renal failure, uremia, hepatic failure, acute respiratory distress syndrome, neurologic dysfunction such as stupor or coma, and death. Non–life-threatening E coli bacteremia may manifest as a sudden onset of fever and chills, tachycardia, tachypnea, and mental confusion. In cases of E coli UTI with urinary tract obstruction, bacteremia or septicemia may ensue.

A retrospective study determined risk factors for mortality in patients with fluoroquinolone-resistant E coli. Results show fluoroquinolone resistance, cirrhosis, and cardiac dysfunction independently predicted mortality. ^[8]

Several cases of E coliendophthalmitis have been reported in patients with diabetes who have UTI or pyelonephritis. ^[9]

Table. Differential Diagnoses of E coli Infection (Open Table in a new window)