In Vitro Antimicrobial Susceptibility Testing of Isolates From Cases of Neonatal Meningitis

Organism (n)Antibiotics
(37)15/34 (44)27/31 (87)b16/18 (89)b29/30 (97)c12/12 (100)9/9 (100)11/13 (85)
(35)32/32 (100)13/13 (100)16/16 (100)
Other Gram-negativeAMPGENTOBCEF (third)MEROCIPaPIP-TAZa
(24)d,e,f,g,h1d/4(6)12/13 (92)g7/8 (95)g12/16 (75)h11/11 (100)4/4 (100)5/7 (71)
Other Gram-positiveAMPCEF (third)VAN
(17)i,j,k,l,m9/9 (100)l6/6 (100)j,k,l8/8 (100)
  • Numbers represent susceptible isolates/isolates tested (% susceptible). AMP, ampicillin; CEF (third), third-generation cephalosporin; CIP, ciprofloxacin; GEN, gentamicin; MERO, meropenem; PIP-TAZ, piperacillin-tazobactam; TOB, tobramycin; VAN, vancomycin.

  • a Not routinely recommended for treatment of neonatal meningitis.

  • b Four isolates of E coli (from 4 patients) were resistant to aminoglycosides: 2 GEN resistant (TOB not tested), 1 GEN resistant and TOB intermediate, 1 resistant to both GEN and TOB. All 4 isolates were resistant to AMP and susceptible to CEF (third).

  • c One isolate of E coli from a 2-day-old term infant diagnosed with meningitis on the postpartum ward was resistant to AMP, CEF (third), and sensitive to GEN, TOB, and MERO.

  • d Antimicrobial susceptibility testing was availabe for only 1 of 4 Neisseria meningitidis isolates. That isolate was AMP and CEF (third) sensitive.

  • e Of 3 cases of H influenzae, 2 isolates were resistant to AMP and sensitive to CEF (third) and the third case did not have susceptibility testing available.

  • f Of 5 isolates of Klebsiella spp., 4 out of 4 cases tested were resistant to AMP, 3 out of 3 cases were sensitive to GEN, and 4 out of 4 cases were sensitive to CEF (third).

  • g One isolate of S marcescens from a 24-week premature male infant diagnosed with meningitis on day 15 of life in the NICU was resistant to AMP, GEN, TOB, CEF (third), and sensitive to MERO and CIP.

  • h E cloacae (n = 6), S marcescens (n = 3), C sakazakii (n = 2), and P stutzeri (n = 1) may be presumed resistant to AMP and CEF (third) although this was not always tested or reported. All isolates that were tested were sensitive to MERO.

  • i One isolate of S pneumoniae and 7 additional isolates of nonGroup B streptococci (S gallolyticus, S anginosus, viridans group streptococci), were all sensitive to AMP. When reported, all isolates were also sensitive to CEF (third) and VAN.

  • j One isolate of Enterococcus spp. was sensitive to AMP and VAN. Presumed resistant to CEF (third).

  • k For 3 isolates of L monocytogenes (from 3 patients), in vitro susceptibility testing not performed or reported. Treatment of choice was AMP+GEN. Presumed resistant to CEF (third).

  • l One isolate of S aureus (methicillin sensitive) and 2 isolates of coagulase-negative staphylococci would not be adequately treated with AMP+GEN. Testing was not performed or reported for CEF (third). All 3 isolates were sensitive to VAN.

  • m In vitro susceptibility testing not performed or reported for 2 isolates of Bacillus spp.