Cronobacter Support
02-19-2009, 05:59 PM
Marilyn C. Erickson and Jeffrey L. Kornacki*
University of Georgia, Center for Food Safety, Griffin, GA
Introduction
Prompted by recent Enterobacter sakazakii infections in neonates and the large percentage of neonates in intensive care units being fed dry infant formula, FDA has sent a warning letter to health professionals recommending that powdered infant formula not be used in neonatal intensive care settings. To address the concerns of manufacturers and users of powdered infant formula, this white paper summarizes relevant information on illnesses associated with E. sakazakii infections, the protocols for detection of this pathogen, distinguishing biochemical, molecular, and pathogenic characteristics of this pathogen, the ecology of E. sakazakii, and regulations regarding the pathogen in foods.
General Characteristics
E. sakazakii is a gram-negative straight rod belonging to the Enterobacteriaciae family and qualifies as a coliform bacterium. Having dimensions of 3 μm in length and 1 μm in width, the cells are motile by peritrichous flagella and do not form spores. Prior to 1980, E. sakazakii was referred to as a “yellow-pigmented” Enterobacter cloacae but it was reclassified based on differences in DNA-DNA hybridization, biochemical reactions, antibiotic susceptibility, and production of yellow-pigmented colonies. Two scanning electron microscopic ima ges of this
organism may be found on the SciMat web site (magma.ca/~scimat/E_sakaza.htm).
Illnesses Associated with E. sakazakii
Infections associated with E. sakazakii have been relatively rare. A review article published in Medicine in 2001 summarized the literature from 1960 to 1999 and found in the English literature only 31 cases of E. sakazakii
infections in neonates, infants, and children, and 4 cases among adults. In the foreign-language literature for which English abstracts were available, 5 additional cases of E. sakazakii infections were located. Since that
review, three additional case studies have been reported. One involved 12 neonates in Belgium associated with an outbreak in June-July 1998, the second involved 2 neonates and 3 infants in Israel (reported in 2001), and the third occurred in Tennessee in 2001 and involved one neonatal fatality and several other infants who were colonized with the pathogen. An additional case of E. sakazakii meningitis resulting in an infant's death in
Belgium and an E. sakazakii infection in a hospitalized neonate in Chattanooga, TN, occurred in 2002. Despite the low frequency of reported infections, the high mortality rate (33%) and severe neurologic impairment in many survivors has generated a high level of concern for E. sakazakii infections.
Risk Factors of Infected Patients
Among the 31 cases involving neonates, infants, and children, ages ranged from 3 days to 4 years with 50% £ 1 week of age and about 75% < 1 month of age. Low birth weights of 2.5 kg or less have also been identified as a distinguishing feature in about 75% of infected patients. These conditions suggest that infected individuals may be immunocompromised or are lacking sufficient colonization of the gastrointestinal tract with normal bacterial flora to compete with the opportunistic pathogen, E. sakazakii. Similarly, in the adult cases, most had underlying diseases (i.e. malignancies) that could have predisposed them to infection by E. sakazakii. In otherwise healthy individuals, E. sakazakii infections are unknown . There are cases, however, from which E. sakazakii has been
isolated from specimens of patients and no signs of infection have been observed.
University of Georgia, Center for Food Safety, Griffin, GA
Introduction
Prompted by recent Enterobacter sakazakii infections in neonates and the large percentage of neonates in intensive care units being fed dry infant formula, FDA has sent a warning letter to health professionals recommending that powdered infant formula not be used in neonatal intensive care settings. To address the concerns of manufacturers and users of powdered infant formula, this white paper summarizes relevant information on illnesses associated with E. sakazakii infections, the protocols for detection of this pathogen, distinguishing biochemical, molecular, and pathogenic characteristics of this pathogen, the ecology of E. sakazakii, and regulations regarding the pathogen in foods.
General Characteristics
E. sakazakii is a gram-negative straight rod belonging to the Enterobacteriaciae family and qualifies as a coliform bacterium. Having dimensions of 3 μm in length and 1 μm in width, the cells are motile by peritrichous flagella and do not form spores. Prior to 1980, E. sakazakii was referred to as a “yellow-pigmented” Enterobacter cloacae but it was reclassified based on differences in DNA-DNA hybridization, biochemical reactions, antibiotic susceptibility, and production of yellow-pigmented colonies. Two scanning electron microscopic ima ges of this
organism may be found on the SciMat web site (magma.ca/~scimat/E_sakaza.htm).
Illnesses Associated with E. sakazakii
Infections associated with E. sakazakii have been relatively rare. A review article published in Medicine in 2001 summarized the literature from 1960 to 1999 and found in the English literature only 31 cases of E. sakazakii
infections in neonates, infants, and children, and 4 cases among adults. In the foreign-language literature for which English abstracts were available, 5 additional cases of E. sakazakii infections were located. Since that
review, three additional case studies have been reported. One involved 12 neonates in Belgium associated with an outbreak in June-July 1998, the second involved 2 neonates and 3 infants in Israel (reported in 2001), and the third occurred in Tennessee in 2001 and involved one neonatal fatality and several other infants who were colonized with the pathogen. An additional case of E. sakazakii meningitis resulting in an infant's death in
Belgium and an E. sakazakii infection in a hospitalized neonate in Chattanooga, TN, occurred in 2002. Despite the low frequency of reported infections, the high mortality rate (33%) and severe neurologic impairment in many survivors has generated a high level of concern for E. sakazakii infections.
Risk Factors of Infected Patients
Among the 31 cases involving neonates, infants, and children, ages ranged from 3 days to 4 years with 50% £ 1 week of age and about 75% < 1 month of age. Low birth weights of 2.5 kg or less have also been identified as a distinguishing feature in about 75% of infected patients. These conditions suggest that infected individuals may be immunocompromised or are lacking sufficient colonization of the gastrointestinal tract with normal bacterial flora to compete with the opportunistic pathogen, E. sakazakii. Similarly, in the adult cases, most had underlying diseases (i.e. malignancies) that could have predisposed them to infection by E. sakazakii. In otherwise healthy individuals, E. sakazakii infections are unknown . There are cases, however, from which E. sakazakii has been
isolated from specimens of patients and no signs of infection have been observed.