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Hearing loss in experimental pneumococcal meningitis increases after pretreatment with G-CSF

Abstract number: 902_p893

Brandt C.

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Background:

Mechanisms leading to hearing loss in pneumococcal meningitis is poorly understood.

Objective:

Boost of systemic neutrophil count by G-CSF prior to infection leads to diminished growth of pneumococci in experimental meninigitis and improves survival. Whether this protective effect also includes attenuation of hearing loss is reported here.

Materials and methods:

Rats – infected intracisternally with ~1 × 105 S. pneumoniae serotype 3 – were randomly allocated to receive G-CSF (10 mg/kg s.c. TD) 48 h prior to infection (n = 16), late treatment (28 h postinfection, n = 16) or no G-CSF (n = 22). All animals also received ceftriaxone started 28 h postinfection. Infection was documented by blood and CSF tap 24 h post infection. Just before, 24 h and 7 days after infection, assessments of hearing was made by measurements of distortion product otoacoustic emissions (DPOAE) at f2 = 4–70 kHz and by assessment of hearing thresholds by auditory brain stem responses (ABR) at 52 kHz in levels from 20 to 100 dB SPL.

Results:

24-h postinfection hearing loss was significantly increased in G-CSF treated animals compared with untreated (hearing loss in 37.5 vs. 14.3% of animals from f2 = 10–50 000 Hz and 75 vs. 42.9%f2 > 50 000 Hz, respectively, Mann–Whitney, P = 0.026). On day 8 postinfection among surviving animals, severity of hearing loss in G-CSF pretreated animals was furthermore increased compared with the control group (severe hearing loss in 92.3 vs. 50% from f2 = 10–65 000 Hz, respectively, Mann–Whitney, P = 0.013). Late G-CSF treatment did not affect hearing loss significantly compared with the control group.

Conclusion:

Increased systemic neutrophil level at time of infection increased risk of hearing loss and development of deafness in a rat model of experimental meningitis despite better control of bacterial growth and better survival. Neutrophils contribute to the sensorineural hearing loss seen in experimental meningitis.

Figure 1.  DP-grams from control and G-CSF pretreatment groups 7 days after infection.

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Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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