Klebsiella pneumoniae Isolates from Meningitis: Epidemiology, Virulence and Antibiotic Resistance

Abstract

Klebsiella pneumoniae (KP) resistance to broad-spectrum cephalosporin (BSC) in meningitis is important because of limited therapeutic options. To investigate the antibiotic resistance, virulence and epidemiology of KP in meningitis, we conducted a retrospective study for 33 non-metastatic isolates, including primary meningitis (n = 20) and post-craniotomy meningitis (n = 13) collected from 1999 to 2013. BSC resistance was found in 9 (27.3%) isolates, all from post-craniotomy meningitis, harboring bla _SHV-5 (n = 6), bla _CMY-2 (n = 2), bla _DHA-1 (n = 2), and bla _TEM-1B (n = 1). Positive virulence factors were hypermucoviscosity (n = 22), larger bacterial size (n = 24), virulent capsule serotypes (n = 24, K2, 11; K1, 5; K57, 3; K5, 2; K20, 2 and K54, 1), rmpA (n = 23), rmpA ₂ (n = 20), aerobactin gene (n = 22) and high-grade serum resistance (n = 23, 69.7%). Higher mouse lethality (LD₅₀ < 10⁶) was found in 16 isolates (48.5%). Post-craniotomy isolates were significantly less virulent than primary meningitis isolates, except for similar serum resistance capability. The pulsotype and sequence typing (ST) results were diverse. A minor cluster with pulsotype C and ST23 (n = 5) was identified in primary meningitis isolates. In conclusion, virulence factors and BSC resistance corresponded to about 70% and 30% of KP meningitis isolates respectively. BSC remains appropriate for treating primary meningitis, whereas meropenem is indicated for post-craniotomy meningitis empirically.

Figure 1

Fingerprinting profiles (A to S) of XbaI-digested genomic DNA using the Dice coefficient and UPGMA for Klebsiella pneumoniae cerebrospinal fluid isolates collected in Taiwan. Eight pulsotypes (C, E, H, I, J, N, P, and R) show a Dice similarity coefficient of more than 80%. Corresponding MLST (multilocus sequence typing) and capsule K serotype of each isolate were presented. *One nucleotide change; x, unidentified, non-virulent capsule K types, i.e., not for K1, K2, K5, K20, K54, K57 types.

Figure 2

Brain imaging studies of patients with Klebsiella pneumoniae meningitis from post-craniotomy meningitis groups (no. 1–6) and primary meningitis group (no. 7–12). No. 1, strain KP1050, hydrocephalus (computed tomography, CT); No. 2, strain KP1051, brain edema with compression effect (CT); No. 3, strain KP1052, brain abscess (CT); No. 4, strain KP1053, brain abscess (CT); No. 5, strain KP1054, subdural effusion (CT); No. 6, strain KP-960, subdural effusion (CT); No. 7, strain KP-958, ventriculitis (Magnetic Resonance Imaging, MRI); No. 8, strain KP-959, brain abscess (CT); No. 9, strain KP-961, hydrocephalus; No. 10, KP-962, essentially intact in brain parenchyma (CT); No. 11, strain KP-963, ventriculitis (MRI); and No. 12, strain KP-966, brain abscess (CT).