C-186. AmpC Type Beta-Lactamase Enterobacter cloacae Causing Neonatal Meningitis

S. M. Juretschko1,2, T. K. Beavers-May1, H. D. Maples2, S. H. Stovall1,2;
1Arkansas Children's Hosp., Little Rock, AR, 2Univ. of Arkansas for Med. Sci., Little Rock, AR.

Background: Neonatal meningitis is inflammation of the meninges due to viral or bacterial invasion, the latter usually more severe and more likely to cause permanent sequelae. Group B Streptococcus (S. agalacticae) is the most common pathogen followed by Escherichia coli and Listeria monocytogenes, accounting for 75% of all neonatal meningitis. Other important pathogens are Enterococcus sp. and Gram negative enteric organisms, such as species of Klebsiella, Citrobacter and Enterobacter. Here we report a case of neonatal meningitis and sepsis due to Enterobacter cloacae harboring an AmpC type β-lactamase. Case report: An eleven day old Caucasian female was transported via helicopter to Arkansas Children’s Hospital (ACH) from an outside hospital due to suspected bacterial meningitis and bacteremia. The patient had a 2 day history of 102º F fever, irritability, intermittent excessive sleep and poor feeding. Septic work up including lumbar puncture was performed. CSF showed WBC count of 13,000 and glucose of 0. Antibiotic therapy was initiated with meningitic doses of ampicillin and cefotaxime. Gram stains from positive blood cultures and CSF at the outside hospital and at ACH showed Gram negative rods. On day 1 after admission the blood culture grew E. cloacae susceptible to all antibiotics tested but cephalothin and ampicillin (BD-Phoenix). On day 2 the CSF culture also showed E. cloacae, resistant to all cephalosporins but cefepime, suggesting an AmpC mediated β-lactamase. Antibiotic regimen was changed immediately to meropenem and gentamicin. The patient improved after day 3 and was discharged on day 9 to complete a 21 day total course of therapy of meropenem alone. Conclusion: The traditional empiric therapy for neonatal meningitis, ampicillin and cefotaxime, has to be carefully considered and evaluated when dealing with Gram negative enterics, especially those capable of producing β-lactamases. Additionally, the need for repeated susceptibility testing of organisms after exposure to cephalosporins is warranted to help detect derepressed resistance mechanisms. The use of an aminoglycoside in addition to a carbapenem instead of an extended spectrum cephalosporin may be warranted.