Combining Ceftriaxone with Doxycycline and Daptomycin Reduces Mortality, Neuroinflammation, Brain Damage, and Hearing Loss in Infant Rat Pneumococcal Meningitis

Abstract

Despite appropriate antibiotic therapy, pneumococcal meningitis (PM) is associated with a case fatality rate of up to 30% in high-income countries. Survivors often suffer from severe lifelong disabilities. An excessive inflammatory reaction drives the pathophysiology, leading to brain damage and neurologic sequelae. We aimed to improve the outcome of experimental PM by simultaneously targeting different pathophysiological mechanisms with combined adjunctive therapies previously shown to be neuroprotective. In vitro, the anti-inflammatory effects of doxycycline and daptomycin were evaluated on primary rat astroglial cells stimulated with Streptococcus pneumoniae. Eleven-day-old infant Wistar rats were infected intracisternally with S. pneumoniae and randomized for treatment with ceftriaxone or combination adjuvant therapy consisting of ceftriaxone, daptomycin, and doxycycline. During acute PM, combined-adjuvant therapy with ceftriaxone, daptomycin, and doxycycline increased the survival rate from 64.1% to 85.8% (P < 0.01) and alleviated weight loss compared to ceftriaxone monotherapy (P < 0.01). Levels of inflammatory cytokines were significantly reduced by combined-adjuvant therapy in vitro (P < 0.0001) and in cerebrospinal fluid in vivo (P < 0.05). In infected animals treated with combined adjunctive therapy, cortical damage was significantly reduced (P < 0.05), and animals showed a trend toward better hearing capacity 3 weeks after the infection (P = 0.089), an effect which was significant in mildly infected animals (48 decibels [dB] versus 67.22 dB; P < 0.05). These mildly infected animals showed significantly reduced cochlear fibrous occlusion (P < 0.01). By combining nonbacteriolytic daptomycin and anti-inflammatory doxycycline with ceftriaxone, the previously reported beneficial effects of the drugs were cumulated and identified the triple-antibiotic therapy as a promising therapeutic option for pediatric PM.

Combined therapy with ceftriaxone and doxycycline does not improve the outcome of meningococcal meningitis in mice compared to ceftriaxone monotherapy

“…AU, arbitrary units refer to the results of statistical analysis */**, statistically significant differences compared to control mice (saline); *, p < 0.05; **, p < 0.01 had an impact on MMP-9 activity in vivo. In contrast to the literature on adjuvant DOX in experimental PM [22,46], in our case no significant differences in clinical parameters, inflammatory mediators and brain damage emerged between CRO and CRO + DOX, suggesting that adjunctive DOX does not offer significant benefits over CRO monotherapy in the MM model.…”

“…The efficacy of adjuvant DOX was assessed in two separate studies where the molecule was tested alone [22] or in combination with daptomycin [46] in an infant rat model of PM. In both reports, adjunctive DOX proved to be very effective at improving animal survival, reducing injury to brain and cochlea, and diminishing hearing loss compared to rats administered with CRO [22,46]. In our case, animals in the CRO + DOX group presented improved clinical scores (p = 0.0062), increased survival (p = 0.017), reduced cerebral hemorrhages (p = 0.029), and lower levels of MMP-9 in the brain (p = 0.046) in comparison with untreated controls.…”

“…Several synthetic MMP inhibitors (i.e., batimastat, GM6001, BB1001, TNF-484, Ro 32–7315, Trocade, and DOX) have been tested in experimental PM, and different outcomes were observed in infected animals [ 12 ]. Cortical necrosis was consistently attenuated with all inhibitors [ 18 , 22 , 33 , 41 – 46 ], while reduced hippocampal apoptosis [ 33 , 41 , 44 , 45 ], increased survival [ 22 , 33 , 41 , 45 , 46 ], decreased hearing loss [ 22 , 46 ], and improved learning and memory functions [ 41 , 44 , 45 , 47 ] were achieved with specific molecules.…”

Adjuvant Cannabinoid Receptor Type 2 Agonist Modulates the Polarization of Microglia Towards a Non-Inflammatory Phenotype in Experimental Pneumococcal Meningitis

“…Mixed glial cultures consisting of microglial and astroglial cells were isolated from infant rat brains at postnatal day 3 (P3) as previously described (Muri et al, 2019b). Cortex was mechanically homogenized in PBS by pipetting up and down, and resuspended in DMEM (Sigma-Aldrich, Merk Switzerland) containing 5% FCS (Biochrom, Germany), 1% GlutaMAX TM (ThermoFisher, Switzerland) and antibiotic-antimycotic solution (100 units/ml penicillin and streptomycin, 0,25 µg/ml Amphotericin B, Thermofisher, Switzerland) and plated in a poly-L-ornithine-coated T75 flask.…”

Repetitive transcranial magnetic stimulation activates glial cells and inhibits neurogenesis after pneumococcal meningitis

“…Astroglial cells were isolated from the brains of infant Wistar rats at postnatal day 3 (P3) received from the Central Animal Facility of the Department for BioMedical Research of the University of Bern-as previously described [38,39]. The rats were sacrificed by decapitation and brains were isolated.…”