Xiao et al. from Hangzhou, retrospectively reviewed the clinical course and outcome of nine cases of meningitis due to Acinetobacter baumannii in children and reviewed the relevant literature.
Seven patients had a history of neurosurgery, and the average time from the first surgery to cerebrospinal fluid (CSF) culture in these seven patients was 23.71 ± 17.43 days. Of all nine patients, four patients showed MDR isolates, two showed XDR isolates, and one showed pan-drug-resistant (PDR) isolates. Three patients received an intrathecal injection of amikacin. Two patients received intravenous colistin (5 mg/kg), and one received polymyxin B (2 mg/kg). The mean hospitalization duration was 39.44 days. Four patients eventually died: two with MDR Acinetobacter, one with PDR Acinetobacter, and one with susceptible Acinetobacter. Two of them still had positive CSF cultures at death.
Acinetobacter baumannii meningitis is usually associated with neurosurgery and the placement of foreign material, and it usually has a high mortality. Intrathecal or intraventricular polymyxin administration is expected to be an effective choice for meningitis but requires further study 1).
Thirty-four patients presented nosocomial meningitis/ventriculitis; 11 (32.5 %) were included in the intravenous colistin (IVC group) and 23 (67.6 %) in the intrathecal/intraventricular colistin (ITC group). The most frequent isolated bacteria were Acinetobacter baumannii. The mean dose was 170,000 (±400) IU and the duration of intraventricular treatment was 16.0 (±8.3) days. The duration of intravenous treatment was 16.0 (±8.3) days in the ITC group and 15.3 ± 7.6 days in IVC group. Hospital mortality was significantly lower in the ITC group compared with the IVC group (13 vs. 72.7 %, p = 0.001).
The combination of intravenous plus intraventricular (IV-IVT) colistin therapy may improve outcomes in patients attending with meningitis/ventriculitis due to multi-drug resistance infections 2).
In an 11-year period, information on 18 consecutive patients with extensively drug-resistant A. baumannii ventriculomeningitis was collected. Infection was defined on the basis of (i) isolation of A. baumannii from the cerebrospinal fluid (CSF); (ii) laboratory evidence of CSF infection; (iii) signs/symptoms of central nervous system (CNS) infection. Patients were divided into group 1 (nine patients, IV colistin alone) and group 2 (nine patients, IV plus IVT colistin).
Cerebrospinal fluid sterilization was documented for 12 of 18 patients (66.6%). The CSF sterilization rate was 33.3% in group 1 and 100% in group 2 (P = 0.009). The mean time to CSF sterilization was 21 days (range 8-48). Five patients died due to A. baumannii CNS infection (all in group 1), and five deaths were unrelated to A. baumannii ventriculomeningitis. Intensive care unit mean length of stay was shorter in group 2 (20.7 vs. 41.6 days, P = 0.046). Crude relative risk ratio of cumulative incidence of persistent CNS infection in group 1 versus group 2 was 13. No cases of chemical meningitis due to intrathecal colistin administration were encountered 3).
Treatment results of six post-neurosurgical ventriculitis and meningitis cases caused by extensively drug-resistant Acinetobacter baumannii after application of an intraventricular loading dose of 500000 IU (40 mg) of colistin followed by a dose of 125000-250000 IU (10-20 mg) every 24-48 h plus parenteral colistin are reported. Simultaneous bacteraemia with an identical Acinetobacter strain was observed in three patients. The mean duration of treatment was 17.2 days (range 15-21 days) and the median time of sterilisation of cerebrospinal fluid was 2.5 days (range 1-5 days). All patients were cured, however one patient presented with chemical meningitis and one with chemical ventriculitis, conditions that clinically and biochemically resemble bacterial meningitis 4).
In a case series of seven Thai patients and 17 patients identified in the literature, clinical and microbiological cure rates with IT/IVT colistin therapy were 83% and 92%, respectively. Three patients (13%) developed chemical ventriculitis and one (4%) experienced treatment-associated seizures. Death was associated with delayed IT/IVT colistin therapy compared to survival (mean time from diagnosis to IT/IVT colistin, 7 vs. 2 days; p 0.01). The only independent predictor of mortality was the severity of illness (APACHE II score > 19, adjusted odds ratio 49.5; 95% CI 1.7-1428.6; p 0.02). This case series suggests that administration of primary or adjunctive IT/IVT colistin therapy was effective for drug-resistant A. baumannii CNS infection 5).
Two patients with multiresistant Acinetobacter baumannii central nervous system infection, successfully treated with either intravenous and/or intraventricular colistin are presented. Unresolved issues such as dose and duration of intraventricular colistin are discussed 7).
Five patients, all were admissions to the neurosurgical ICU and all were cured of their CNS infections. Three cases were complicated by drug-induced aseptic meningitis or ventriculitis.
This largest case series till 2006 shows that direct instillation of colistin into the CNS may cause chemical meningitis or ventriculitis but it is an effective treatment option for MRAB CNS infection. Further study of dosing regimens is needed 8).