Cronobacter Support
03-17-2009, 09:09 AM
Physical
Bacteremia
Physical examination findings consistent with systemic inflammatory response syndrome (SIRS) include heart rate that exceeds 90 bpm, a respiratory rate of greater than 20, and temperature of greater than 38°C or less than 36°C.
More than 80% of children and adults with Enterobacter bacteremia develop fever.
Hypotension and shock occur in as many as one third of cases.
Disseminated intravascular coagulation, jaundice, acute respiratory distress syndrome, and other organ failures reflect the severity of septic shock.
Purpura fulminans and hemorrhagic bullae usually observed with meningococci or viruses causing hemorrhagic fever may be part of the clinical presentation of Enterobacter bacteremia.
Ecthyma gangrenosum, usually associated with Pseudomonas or Aeromonas bacteremia, may also be observed.
Cyanosis and mottling is frequently reported in children with Enterobacter bacteremia.
Lower respiratory tract infections
The physical manifestations caused by Enterobacter are not specific for infection with these bacteria. Enterobacter lower respiratory tract infections can manifest identically to those caused by S pneumoniae or other organisms.
The physical examination findings may include apprehension, high fever or hypothermia, tachycardia, hypoxemia, tachypnea, and cyanosis. Patients with pulmonary consolidation may present with crackling sounds, dullness to percussion, tubular breath sounds, and egophony. Pleural effusion may manifest as dullness to percussion and decreased breath sounds.
Causes
Enterobacter is a gram-negative bacillus that belongs to the Enterobacteriaceae family. Other members of this family include Klebsiella, Escherichia, Citrobacter, Serratia, Salmonella, and Shigella species, among many others. Enterobacteriaceae are the most common bacterial isolates recovered from clinical specimens. These bacteria have an outer membrane that contains, among other things, lipopolysaccharides from which lipid-A plays a major role in sepsis. Lipid-A, also known as endotoxin, is the major stimulus for the release of cytokines, which are the mediators of systemic inflammation and its complications.
In the microbiology laboratory, colonies of Enterobacteriaceae appear large, dull-gray, and dry or mucoid on sheep blood agar. All Enterobacteriaceae ferment glucose and, consequently, are able to grow in aerobic and anaerobic atmospheres.
MacConkey agar is a lactose-containing medium that is selective for nonfastidious gram-negative bacilli such as Enterobacteriaceae. Using the enzymes beta-galactosidase and beta-galactoside permeases, the most frequently encountered species of Enterobacter strains activate the pH indicator (neutral red) included in MacConkey agar, giving a red stain to the growing colonies. Klebsiella and Enterobacter species may appear similar as mucoid colonies but can be differentiated with a few specific tests. In contrast to Klebsiella species, Enterobacter organisms are motile, usually ornithine decarboxylase-positive, and urease-negative.
Many different species comprise the genus Enterobacter. Some have never been associated with human infections. The most commonly isolated species include E cloacae and E aerogenes, followed by E sakazakii, which produces a characteristic yellow pigment. Other species rarely encountered in the clinic include Enterobacter asburiae, Enterobacter gergoviae, Enterobacter taylorae, Enterobacter hormaechei, and Enterobacter cancerogenus. Enterobacter agglomerans has been removed from the genus Enterobacter and renamed Pantoea agglomerans.
Bacteremia
Physical examination findings consistent with systemic inflammatory response syndrome (SIRS) include heart rate that exceeds 90 bpm, a respiratory rate of greater than 20, and temperature of greater than 38°C or less than 36°C.
More than 80% of children and adults with Enterobacter bacteremia develop fever.
Hypotension and shock occur in as many as one third of cases.
Disseminated intravascular coagulation, jaundice, acute respiratory distress syndrome, and other organ failures reflect the severity of septic shock.
Purpura fulminans and hemorrhagic bullae usually observed with meningococci or viruses causing hemorrhagic fever may be part of the clinical presentation of Enterobacter bacteremia.
Ecthyma gangrenosum, usually associated with Pseudomonas or Aeromonas bacteremia, may also be observed.
Cyanosis and mottling is frequently reported in children with Enterobacter bacteremia.
Lower respiratory tract infections
The physical manifestations caused by Enterobacter are not specific for infection with these bacteria. Enterobacter lower respiratory tract infections can manifest identically to those caused by S pneumoniae or other organisms.
The physical examination findings may include apprehension, high fever or hypothermia, tachycardia, hypoxemia, tachypnea, and cyanosis. Patients with pulmonary consolidation may present with crackling sounds, dullness to percussion, tubular breath sounds, and egophony. Pleural effusion may manifest as dullness to percussion and decreased breath sounds.
Causes
Enterobacter is a gram-negative bacillus that belongs to the Enterobacteriaceae family. Other members of this family include Klebsiella, Escherichia, Citrobacter, Serratia, Salmonella, and Shigella species, among many others. Enterobacteriaceae are the most common bacterial isolates recovered from clinical specimens. These bacteria have an outer membrane that contains, among other things, lipopolysaccharides from which lipid-A plays a major role in sepsis. Lipid-A, also known as endotoxin, is the major stimulus for the release of cytokines, which are the mediators of systemic inflammation and its complications.
In the microbiology laboratory, colonies of Enterobacteriaceae appear large, dull-gray, and dry or mucoid on sheep blood agar. All Enterobacteriaceae ferment glucose and, consequently, are able to grow in aerobic and anaerobic atmospheres.
MacConkey agar is a lactose-containing medium that is selective for nonfastidious gram-negative bacilli such as Enterobacteriaceae. Using the enzymes beta-galactosidase and beta-galactoside permeases, the most frequently encountered species of Enterobacter strains activate the pH indicator (neutral red) included in MacConkey agar, giving a red stain to the growing colonies. Klebsiella and Enterobacter species may appear similar as mucoid colonies but can be differentiated with a few specific tests. In contrast to Klebsiella species, Enterobacter organisms are motile, usually ornithine decarboxylase-positive, and urease-negative.
Many different species comprise the genus Enterobacter. Some have never been associated with human infections. The most commonly isolated species include E cloacae and E aerogenes, followed by E sakazakii, which produces a characteristic yellow pigment. Other species rarely encountered in the clinic include Enterobacter asburiae, Enterobacter gergoviae, Enterobacter taylorae, Enterobacter hormaechei, and Enterobacter cancerogenus. Enterobacter agglomerans has been removed from the genus Enterobacter and renamed Pantoea agglomerans.