title: Listeria and enterococcal infections in neonates 28 days of age and younger: is empiric parenteral ampicillin still indicated?
abstract: BACKGROUND
  Empiric parenteral ampicillin has traditionally been used to treat listeria and enterococcal serious bacterial infections (SBI) in neonates 28 days of age or younger. Anecdotal experience suggests that these infections are rare. Existing data suggest an increasing resistance to ampicillin. Guidelines advocating the routine use of empiric ampicillin may need to be revisited.
  
  
  OBJECTIVE
  This study aimed to describe the epidemiology and ampicillin sensitivity of listeria and enterococcal infections in neonates 28 days of age and younger who presented to 2 pediatric emergency departments (ED) in Michigan.
  
  
  METHODS
  We conducted a 2-center, retrospective chart review (2006-2010) of neonates 28 days of age or younger who were evaluated for SBI in the ED. We abstracted and compared relevant demographic, historical and physical details, laboratory test results, and antibiotic sensitivity patterns to ampicillin from the eligible patient records.
  
  
  RESULTS
  We identified SBI in 6% (72/1192) of neonates 28 days of age or younger who were evaluated for SBI, of which 0.08% (1/1192) neonates had enterococcal bacteremia and 0.08% (1/1192) neonates had listeria bacteremia. A total of 1.4% (15/1192) of patients had enterococcal urinary tract infection (UTI). Urinalysis is less helpful as a screening tool for enterococcal UTI when compared with Escherichia coli UTI (P < 0.001). Seventy-three percent (11/15) of urine isolates had an increase of minimal inhibitory concentrations, which indicate gradual development of resistance to ampicillin.
  
  
  CONCLUSIONS
  Listeria is an uncommon cause of neonatal SBI in febrile neonates who presented to the ED. Empiric use of ampicillin may need to be reconsidered if national data confirm very low listeria and enterococcal prevalence and high ampicillin resistance patterns.
authors.affiliation: From the *Division of Pediatric Emergency Medicine, Children's Hospital of Michigan, Wayne State University, Detroit; and †Departments of Emergency Medicine and ‡Pediatrics, University of Michigan, Ann Arbor, MI.
authors.forename: Ameer
authors.initials: A
authors.lastname: Hassoun
authors.forename: Curt
authors.initials: C
authors.lastname: Stankovic
authors.forename: Alexander
authors.initials: A
authors.lastname: Rogers
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Duffy
authors.forename: Marwan
authors.initials: M
authors.lastname: Zidan
authors.forename: Clare
authors.initials: C
authors.lastname: Levijoki
authors.forename: Rachel
authors.initials: R
authors.lastname: Stanley
authors.forename: Prashant
authors.initials: P
authors.lastname: Mahajan
mesh_terms: D000667:Ampicillin / Q000627:therapeutic use*; D000668:Ampicillin Resistance; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D003430:Cross-Sectional Studies; D004636:Emergency Service, Hospital; D016983:Enterococcus; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007263:Infusions, Parenteral; D008088:Listeriosis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D008297:Male; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D012189:Retrospective Studies
chemical_list: D000900:Anti-Bacterial Agents; D000667:Ampicillin