Cronobacter multi-species complex (formerly Enterobacter sakazakii) is a group of gram-negative bacteria that exists in the environment and which can survive in very dry conditions. The natural habitat for Cronobacter is not known. It has been found in a variety of dry foods, including powdered infant formula, skimmed milk powder, herbal teas, and starches. It has also been found in wastewater. Cronobacter illnesses are rare, but they are frequently lethal for infants and can be serious among people with immunocompromising conditions and the elderly.
Infants suspected of having Cronobacter sepsis or meningitis should undergo a full clinical evaluation for sepsis, including blood culture, urine culture, and cerebrospinal fluid culture, and should be given empiric therapy for sepsis immediately. Antimicrobial sensitivity patterns of Cronobacter isolates should be determined because multidrug-resistant strains have been reported. Brain imaging studies of infants with meningitis can help detect brain abscesses and other complications. People with urinary tract infections or serious wound infections should also be treated with antibiotics. If a patient is colonized, rather than infected, with Cronobacter, treatment is not needed.
Major research on disease
Current research on E. sakazakii focuses on the elimination of this coliform from PIF. Investigations into thermal resistance, osmotic tolerance, exopolysaccharide production, and pathogenicity, among others, have been performed, and attempts have been made to identify environmental reservoirs. Only 1 study has suggested the possible existence of an enterotoxin produced by E. sakazakii on the basis of an animal model. Other virulence factors remain to be identified. Furthermore, why infection can occur in all age groups but is more frequent among full-term infants and neonates remains to be understood.
From February 9 through September 19, 1997, eight adult patients at an ambulatory hemodialysis center in Jerusalem, Israel, had gram-negative bacterial BSIs. BSIs in four patients were caused by Escherichia coli, three by P. aeruginosa, two by Enterobacter cloacae, and one by Stenotrophomonas maltophilia; two patients had polymicrobial BSIs. All patients at the hemodialysis center were dialyzed on CS3 hemodialysis machines that had WHOs. All eight patients who had BSIs had been dialyzed on three of 13 dialysis machines. Backflow was observed in the WHOs of the three implicated dialysis machines, and cultures obtained from the WHOs of six of 13 machines were positive for gram-negative organisms. Five of the eight patients, including all four with Escherichia coli BSIs, had been dialyzed on one machine that subsequently was culture-positive for Escherichia coli and P. aeruginosa. Both patients with Enterobacter cloacae BSIs had been dialyzed on a second machine that was culture-positive for Enterobacter cloacae and P. aeruginosa. Escherichia coli isolates obtained from three patients and the WHO of the implicated machine were identical by PFGE.