Acinetobacter baumannii strains isolated from cerebrospinal fluid (CSF) and bloodstream analysed by cgMLST: the dominance of clonal complex CC92 in CSF infections.

A total of 54 unique clinical Acinetobacter baumannii strains isolated from cerebrospinal fluid (CSF) together with 21 bloodstream isolates collected from five tertiary hospitals in East China between April 2013 and November 2016 were studied for antimicrobial susceptibility patterns and the prevalence of antimicrobial resistance genes. Molecular epidemiological characteristics of CSF isolates and the phylogenetic relationship of isolates from different sources were assessed using multilocus sequence typing (MLST) and core genome MLST (cgMLST). Of the 54 CSF isolates, 51 (94.4%) were blaOXA-23-carrying carbapenem-resistant A. baumannii. Their average resistance rate to different classes of antibiotics was extremely high (>90%), except for tigecycline and colistin. According to the Oxford MLST scheme, all CSF isolates fell into 10 defined sequence types (STs) and 4 novel STs. ST195 and ST208 were the leading STs in isolates from either source. A total of 50 CSF isolates and 20 bloodstream isolates were assigned to clonal complex 92 (CC92), revealing a wild distribution of CC92 in the hospitals of East China. In combination with epidemiological data linked in time and space, cgMLST results elucidated intrahospital and interhospital polyclonal dissemination of A. baumannii causing meningitis. Based on cgMLST, there was no correlation between phylogeny and the source of isolation of A. baumannii. These results emphasise that the genetic potential of this pathogen is vast enough to infect multiple human body sites.

Evaluation of Post-operative Meningitis: Comparison of Meningitis Caused by Acinetobacter spp. and Other Possible Causes.

AIM: To analyse postoperative meningitis (POM) after craniotomy, and to compare the clinical characteristics, treatment outcomes and mortality rates of POM that were caused by Acinetobacter spp. or other possible causes. MATERIAL AND METHODS: In this study, POM cases in our hospital between 2008 and 2016 were retrospectively reviewed. Cases were divided into three groups; Acinetobacter spp. meningitis (case group), non-Acinetobacter bacterial meningitis (control group 1) and culture negative meningitis (control group 2). Demographic, clinical, laboratory features, treatment modalities and mortality rates were compared between case and control groups. RESULTS: A total of 112 patients with POM were included in the study. Cerebrospinal fluid (CSF) culture results were negative in 50 (44.6%) patients; bacteria were isolated from CSF of 62 (55.3%) patients. Acinetobacter spp. was isolated from 28 (45%) patients, while bacteria other than Acinetobacter spp. were detected in 34 (55%) patients. No significant differences were observed between case and control groups in terms of age, gender, comorbidity and operation type. For the case group, change of treatment according to culture result was significantly different from control groups (p < 0.001). Mortality was 55.6% in the case group, 24.2% in control group 1 (p=0.013), and 24% in control group 2 (p=0.006). In multivariate analysis, isolation of Acinetobacter spp. from CSF culture [OR < sub > adj < /sub > 5.2, 95% confidence interval (CI):1.2-22.0, p=0.026] and inappropriate treatment (OR < sub > adj < /sub > 15.7, 95%CI:3.6-68.9, p < 0.001) were determined to be independent risk factors for mortality. CONCLUSION: Postoperative meningitis, especially caused by Acinetobacter spp., and its inappropriate empirical treatment are associated with high mortality.

Fast and reliable diagnosis of XDR Acinetobacter baumannii meningitis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Bacterial meningitis is a medical emergency needing quick and timely diagnosis. Even though meningitis caused by Acinetobacter baumannii is relatively rare, it is associated with high mortality rates especially in neurosurgery patients and represents a serious therapeutic problem due to the limited penetration of effective antibiotics into the cerebrospinal fluid. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) has been effectively used as a rapid method for microbial identification. In this case report we identified A. baumanni by MALDI-TOF technique directly from the CSF drawn from the external ventricular drainage of a patient with severe confusional state and signs of meningism. Simultaneously the antibiotic susceptibility test was performed by automated method from the pellet of the broth-enriched sample. The MALDI-TOF technique allowed microbial identification in less than 30 minutes, and the susceptibility test result was available in eight hours, thus allowing a fast diagnosis ready for prompt and targeted antimicrobial therapy.

Acute blindness in a dog with Acinetobacter-associated postencephalitic hydrocephalus.

A 10-month-old male Welsh Corgi with a history of acute blindness underwent neuro-ophthalmological testing and magnetic resonance imaging (MRI). Vision testing revealed complete visual deficits but the electroretinograph and pupillary light reflex were normal in both eyes. The motor and sensory functions of the eyelids and eyes were also normal. The MRI revealed compression of the optic chiasm caused by severe ventriculomegaly in the lateral and third ventricles. Such lesions are associated with inflammatory stenotic lesions in the mesencephalic aqueduct. Moderate neutrophilic pleocytosis was observed during cerebrospinal fluid analysis and Acinetobacter lwoffii was isolated, leading to a diagnosis of Acinetobacter-positive obstructive hydrocephalus. This is the first reported case of culture-proven Acinetobacter-associated postencephalitic hydrocephalus with acute blindness in a dog.

Intraventricular versus intravenous colistin for the treatment of extensively drug resistant Acinetobacter baumannii meningitis.

BACKGROUND AND PURPOSE: Reports on the safety and efficacy of intraventricularly administered (IVT) colistin for the treatment of Acinetobacter baumannii ventriculomeningitis in adults are limited and no comparative studies of IVT colistin versus intravenous (IV) therapy alone have been published. This study compared outcomes of patients with postneurosurgical ventriculomeningitis caused by extensively drug-resistant A. baumannii treated with IV colistin or IV plus IVT colistin. METHODS: 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). RESULTS: 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. CONCLUSIONS: Intraventricular colistin administration is much more effective than IV therapy alone and does not seem to add further toxicity.

The causes and treatment outcomes of 91 patients with adult nosocomial meningitis.

BACKGROUND/AIMS: Frequent pathogens of nosocomial meningitis were investigated and the adequacy of empiric antibiotic therapy was assessed. Outcomes of nosocomial meningitis were also evaluated. METHODS: Ninety-one patients, who were diagnosed and treated for nosocomial meningitis at a single tertiary hospital in Daegu, Korea for 10 years, were included. Medical record and electronic laboratory data on the causative pathogens, antibiotics used, and outcomes were retrospectively investigated. RESULTS: Coagulase-negative Staphylococcus (40.9%) was the most common pathogen, followed by Acinetobacter (32.5%). Both were cultured as a single organism in cerebrospinal fluid (CSF). Seventy-eight patients (85.7%) had infections related to external ventricular drains (EVD). The most common empirical antibiotics were extended-spectrum beta-lactam antibiotics plus vancomycin (35/91, 38.6%). Of the 27 patients who had cultured Acinetobacter in CSF, 10 (37%) were given the wrong empirical antibiotic treatment. Seven of the 27 patients (26.9%) with cultured Acinetobacter died, and overall mortality of the 91 patients was 16.5%. In the multivariate analysis, the presence of combined septic shock (p < 0.001) and a persistent EVD state (p = 0.021) were associated with a poor prognosis. CONCLUSIONS: Acinetobacter is one of the leading pathogens of nosocomial meningitis and may lead to inadequate coverage of empiric antibiotic therapy due to increasing resistance. An EVD should be removed early in cases of suspected nosocomial meningitis, and carbapenem might be required for the poor treatment response.

The Causes and Treatment Outcomes of 91 Patients with Adult Nosocomial Meningitis

BACKGROUND/AIMS: Frequent pathogens of nosocomial meningitis were investigated and the adequacy of empiric antibiotic therapy was assessed. Outcomes of nosocomial meningitis were also evaluated. METHODS: Ninety-one patients, who were diagnosed and treated for nosocomial meningitis at a single tertiary hospital in Daegu, Korea for 10 years, were included. Medical record and electronic laboratory data on the causative pathogens, antibiotics used, and outcomes were retrospectively investigated. RESULTS: Coagulase-negative Staphylococcus (40.9%) was the most common pathogen, followed by Acinetobacter (32.5%). Both were cultured as a single organism in cerebrospinal fluid (CSF). Seventy-eight patients (85.7%) had infections related to external ventricular drains (EVD). The most common empirical antibiotics were extended-spectrum beta-lactam antibiotics plus vancomycin (35/91, 38.6%). Of the 27 patients who had cultured Acinetobacter in CSF, 10 (37%) were given the wrong empirical antibiotic treatment. Seven of the 27 patients (26.9%) with cultured Acinetobacter died, and overall mortality of the 91 patients was 16.5%. In the multivariate analysis, the presence of combined septic shock (p < 0.001) and a persistent EVD state (p = 0.021) were associated with a poor prognosis. CONCLUSIONS: Acinetobacter is one of the leading pathogens of nosocomial meningitis and may lead to inadequate coverage of empiric antibiotic therapy due to increasing resistance. An EVD should be removed early in cases of suspected nosocomial meningitis, and carbapenem might be required for the poor treatment response.

Acinetobacter baumannii isolation in cerebrospinal fluid in a febrile neonate.

We report the isolation of multidrug-resistant Acinetobacter baumannii from the cerebrospinal fluid (CSF) of a neonate suffering from fever and irritability who was initially regarded as aseptic meningitis [CSF analysis: white blood cell (WBC), 14/mm3 (neutrophil 78%); glucose, 41 mg/dl; protein, 52 mg/dl]. The normal range of WBC counts in the CSF is fairly wide, and the symptoms of meningitis are nonspecific in this age group. This patient had several risk factors for Acinetobacter infection, including exposure to antibiotics and previous admission to a neonatal care unit; therefore, it was difficult to judge the import of the isolation of A. baumannii from the CSF in this case. With the increasing prevalence of Acinetobacter species in hospital environments, clinicians may thus be confronted with uncertainty regarding whether isolated A. baumannii is a true pathogen or a contaminant. Thus, clinicians should be familiar with the risk factors for Acinetobacter infection and clinical/laboratory findings of clinically significant CSF Acinetobacter isolates.

Transverse myelitis associated with Acinetobacter baumanii intrathecal pump catheter-related infection.

OBJECTIVE: To describe a late neurologic complication of intrathecal pump implantation and show the methods used for the diagnosis and successful treatment of transverse myelitis in this setting. CASE REPORT: A 32-year-old man with a chronic abdominal pain syndrome presented with right lower-extremity numbness 2 months after the placement of an intrathecal morphine pump. This progressed to bilateral lower extremity and ascending sensory loss to T12-L1 dermatome, significant lower-extremity weakness, constipation with overflow incontinence, and detrusor instability causing urinary incontinence in discrete episodes over the following 2 months consistent with a myelopathy. Magnetic resonance imaging (MRI) of the thoracic spine and cerebrospinal fluid (CSF) analysis were consistent with transverse myelitis. The intrathecal pump was removed and an Acinetobacter baumanii catheter-tip infection was diagnosed. Clinical course improved with the co-administration of intravenous corticosteroids and antibiotics, with significant clinical improvement within 30 days. CONCLUSIONS: Clinicians should recognize transverse myelitis as a possible late complication of intrathecal pump placement. Early medical intervention and removal of the intrathecal pump may be necessary to prevent irreversible spinal cord damage and may support good recovery.

Nontraditional dosing of ampicillin-sulbactam for multidrug-resistant Acinetobacter baumannii meningitis.

A 52-year-old man was admitted to a local hospital with headache, nausea, vomiting, dizziness, photophobia, and confusion after a sudden fall. Progressive changes in neurologic function were noted despite neurosurgical intervention and broad-spectrum antimicrobial coverage. Cerebral spinal fluid (CSF) culture identified Acinetobacter baumannii that was resistant to traditionally recommended therapies of amikacin and imipenem-cilastatin. The organism demonstrated minimum inhibitory concentrations of greater than 32 microg/ml and 8 microg/ml, respectively, for these two agents. Ampicillin 2 g-sulbactam 1 g every 3 hours was administered based on history of therapeutic failure of traditional dosing in our thermal injury population. Repeat CSF cultures after 12 days of ampicillin-sulbactam therapy were negative. After 35 days, the patient's A. baumannii infection was completely resolved. The patient experienced no adverse drug events or toxicity with this high-dosage regimen.

Cerebrospinal meningitis with the presence of Acinetobacter spp.

The study was conducted on 16 strains of Acinetobacter sp. which were isolated from cerebrospinal fluid. The diagnostic material was analysed with the use of automatic BacT/Alert system (Organon Teknika). The analysis was performed in the Department of Microbiology, Medical University in Bydgoszcz. API 20NE system (bioMérieux) enabled the identification of 14 strains (87.5%) as A. baumannii, 1 strain as A. haemolyticus and 1 strain as A. lwoffii. The micro-organisms were isolated from patients whose age ranged between 4 and 66 years. These patients were treated in the departments of Neurosurgery (75.0%), Neurology (18.8%) and Intensive Therapy (6.2%). The infection of cerebrospinal fluid was caused by injury and subsequent exposure to the bacteria present in external environment. Antibiotic-sensitivity of these micro-organisms was evaluated with the help of disc-diffusion method, observing standardisation conditions outlined by NCCLS. All the strains proved sensitive to carbapenems, 15 strains were sensitive to netilmicin, 7 strains--to tobramycin and 7 strains--to amikacin. All the strains displayed multiple resistance. The only exception was A. haemolyticus. The use of two-discs allowed for the detection of ESBLs in 7 A. baumannii strains. Positive results were most frequently obtained after the combination of sublactam and aztreonam. Due to microscopic resemblance between Acinetobacter spp., and bacteria of Neisseria, Moraxella and Haemophilus genus, microbiological diagnostics should not be restricted to microscopic assessment of cerebrospinal fluid and quick serological tests evaluating the antigens of the most frequent aetiological factors. Considering multiple resistance of Acinetobacter spp. to antibiotics, the treatment should be based on sensitivity tests and the ability of a given antibiotic to penetrate into cerebrospinal fluid. In our opinion, both reasonable antibiotic policy as well as observing the principles of hygiene and monitoring infections play equally important roles in the prevention of infections with Acinetobacter spp. Such combined measures may help to prevent the spreading of multiple resistant strains in hospital environment.

Biotyping of Acinetobacter species isolated from clinical samples.

We used the biotyping scheme using carbohydrate substrate utilization test with 14 carbon sources to speciate Acinetobacter isolates from blood and cerebrospinal fluid cultures of patients admitted to the postoperative neurosurgery ICU during January to November 1996. Sixty one patients culture positive for Acinetobacter sp. from blood or cerebrospinal fluid were followed up prospectively. Among these patients, 40 patients had clinically diagnosed infections like bacteriemia or meningitis while in 21 patients the isolation was regarded as contaminants. A. baumanniii was the most common isolate associated with clinical infections while A. lwoffii was more likely to be an environmental contaminant.

Treatment of multidrug-resistant Acinetobacter baumannii meningitis with ampicillin/sulbactam.

The clinical features and the outcomes of eight cases of nosocomial Acinetobacter baumannii meningitis treated with ampicillin/sulbactam are reported. All the patients had fever, neck stiffness or meningeal signs, and a low consciousness level, and in their cerebrospinal fluid (CSF), pleocytosis, a low glucose level, and an elevated protein level were noted. For all CSF isolates of A. baumannii, the MIC of ampicillin/sulbactam was < or = 8/4 microg/mL. The MICs of sulbactam by microdilution in two cases were 4 microg/mL. All isolates were resistant to cefotaxime, ceftriaxone, ceftazidime, ureidopenicillins, ciprofloxacin, and gentamicin. Seven isolates were resistant to imipenem. A. baumannii was isolated from other samples in seven episodes. All patients were treated with ampicillin/sulbactam (seven with 2 g/l g every 6 hours and one with 2 g/l g every 8 hours). Six patients were cured and two patients died of meningitis. There were no side effects with the ampicillin/sulbactam treatment. In conclusion, ampicillin/sulbactam may be effective as therapy for meningitis caused by A. baumanii resistant to imipenem and other beta-lactam drugs.

Acinetobacter meningitis.

10,468 CSF samples from cases of meningitis in different age groups were cultured during 1988-1991. Acinetobacter calcoaceticus was isolated in 12 (5.6%) of 211 positive cultures. The strain were 100% resistant to ampicillin, cotrimoxazole and tetracycline 50% resistant to cephazolin gentamicin and kanamycin but 100% susceptible to chloramphenicol.

Infected ventriculostomy: bacteriology and treatment.

During a period of 6 years 256 patients underwent ventriculostomy as their first operative procedure. Twenty-seven patients (11%) developed CSF-infections, in almost 90% caused by Gram-positive cocci compatible with normal skin flora. The incidence of infection was distributed evenly in the postoperative period. All patients received intravenous and intrathecal antibiotic treatment simultaneously according to the sensitivity test. The treatment was highly effective, and without serious adverse effects.