Clinical and microbiological characteristics of carbapenem-resistant Enterobacteriaceae causing post-operative central nervous system infections in China

OBJECTIVES

Postoperative central nervous system infections (PCNSIs) caused by carbapenem-resistant Enterobacteriaceae (CRE) frequently result in unfavourable outcomes. However, CRE PCNSIs have not been well described from a clinical and microbiological perspective.

METHODS

A total of 254 PCNSIs cases were included (January 2017 through June 2020), and clinical features were compared based on pathogenic classification. Cox regression analysis was performed to assess risk factors for mortality. Antibiotic susceptibility testing and whole genome sequencing were conducted on CRE isolates preserved. MLST, cgMLST, resistance genes and virulence genes were further analysed.

RESULTS

Among 254 PCNSI cases, 15.4% were caused by Enterobacteriaceae including 28 cases by CRE. The 28-day mortality rates for CRE, CSE and non-Enterobacteriaceae PCNSIs were 50.0%, 27.3%, and 7.4%, respectively. 42.9% (12/28) of the CRE PCNSIs patients achieved clinical cure, with 25.0% achieved microbiological clearance. ST11-KL64 carrying blaKPC-2 was dominant in CRE (17/23, 73.9%), and the 28-day mortality rate of its infection was 58.5%. Most CRKP carried rampA/rampA2 genes (17/23, 73.9%).

CONCLUSION

ST11-KL64 CRKP carrying blaKPC-2 dominated among CRE PCNSIs. Targeted anti-infective combination therapy based on ceftazidime/avibactam or amikacin, combined with intrathecal administration of amikacin, was found to be effective. These findings render a new insight into the clinical and microbiological landscape of CRE PCNSIs.

Analysis of tigecycline in the cerebrospinal fluid and serum of patients with Acinetobacter baumannii central nervous system infection

Aim: This study aimed to establish a method to determine tigecycline (TGC) in the cerebrospinal fluid (CSF) and serum of 12 patients with multidrug-resistant Acinetobacter baumannii (MDRAB) central nervous system infection (CNSI) and evaluate the correlation of TGC in CSF and serum samples. Materials & methods: TGC in CSF and serum was detected by high-performance liquid chromatography with tandem mass spectrometry. Results: In all 12 patients, the CSF-to-serum ratio of TGC at a steady-state trough concentration ranged from 21.46 to 44.46%, and the mean value was 31.61 ± 8.13%. The correlation of TGC in CSF and serum was 0.5065. Conclusion: CNSI might have no potential to increase the penetration ability of TGC into the CSF. The correlation between the concentrations of TGC in CSF and serum at steady state was demonstrated to be positive.

Successful Treatment of Severe Post-craniotomy Meningitis Caused by an Escherichia coli Sequence Type 410 Strain Coharboring bla NDM - 5 and bla CTX - M - 65

Intracranial infections caused by multidrug-resistant Gram-negative bacterium have led to considerable mortality due to extremely limited treatment options. Herein, we firstly reported a clinical carbapenem-resistant Escherichia coli isolate coharboring bla NDM - 5 and bla CTX - M - 65 from a patient with post-craniotomy meningitis. The carbapenem-resistant Escherichia coli strain CNEC001 belonging to Sequence Type 410 was only susceptible to amikacin and tigecycline, both of which have poor penetration through the blood-brain barrier (BBB). The bla CTX - M - 65 gene was expressed on a 135,794 bp IncY plasmid. The bla NDM - 5 gene was located on a genomic island region of an IncX3-type plasmid pNDM5-CNEC001. Based on the characteristics of the strain, we presented the successful treatment protocol of intravenous (IV) tigecycline and amikacin combined with intrathecal (ITH) amikacin in this study. Intracranial infection caused by Escherichia coli coharboring bla NDM - 5 and bla CTX - M - 65 is rare and fatal. Continuous surveillance and infection control measures for such strain need critical attention in clinical settings.

Intraventricular administration of tigecycline for the treatment of multidrug-resistant bacterial meningitis after craniotomy: a case report

BACKGROUND

Intracranial infections, especially multidrug-resistant (MDR) bacterial meningitis, are one of the most severe complications after craniotomy and may greatly impact patient outcomes.

CASE PRESENTATION

We report a case of severe MDR Klebsiella pneumonia meningitis after craniotomy that was treated with three different dosages of tigecycline (Pfizer, New York, NY, U.S.A.)via a combined intravenous (IV) and intracerebroventricular (ICV) administration. Here, we discuss the pharmacokinetics (PK) of a combined IV and ICV tigecycline administration for a patient with an intracranial infection after craniotomy.

CONCLUSION

In the present case, three different dosages of tigecycline were administered: 49 mg IV plus 1 mg ICV q12 h, 45 mg IV plus 5 mg ICV q12 h, 40 mg IV plus 10 mg ICV q12 h. The combined IV and ICV administration might improve CSF tigecycline concentrations, and in this case, the methods of administration were safe and effective.

Cerebral Spinal Fluid Penetration of Tigecycline in a Patient with Acinetobacter baumannii Cerebritis

Objective:

To describe cerebral spinal fluid (CSF) penetration of tigecycline.

Case Summary:

A 38-year-old woman experienced a right internal carotid artery dissection and right anterior and middle cerebral artery strokes due to unknown causes and subsequently developed vasogenic edema requiring right hemicraniectomy. Her postoperative course was complicated by multiple infections, and she developed multidrug, carbapenem-resistant Acinetobacter baumannii cerebritis. She was treated with a prolonged course of multiple antibiotics, including 18 days of therapy with tigecycline. Time-paired serum and CSF samples were obtained, and tigecycline concentrations were analyzed by high-performance liquid chromatography. We report serial, steady-state, serum, and CSF concentrations of tigecycline when administered in the Food and Drug Administration-approved dose of 50 mg every 12 hours. CSF concentrations remained relatively stable, suggesting that tigecycline did not accumulate in the CSF, at least in our patient. Tigecycline concentrations in the CSF were between 0.035 and 0.048 mg/L, while corresponding serum concentrations were 0.097–0.566 mg/L. The calculated tigecycline penetration ratio in this patient ranged from 0% to 52%, depending on the calculation methodology utilized.

Discussion:

Concentrations, regardless of sample timing relative to dose, remained relatively stable in the CSF of our patient. The pharmacodynamic profile of tigecycline is not completely elucidated; however, it is presumed that the drug must be at the site of infection for efficacy. Our patient never obtained tigecycline concentrations in excess of the minimum inhibitory concentration for A. baumannii in either the serum or the CSF.

Conclusions:

Our patient experienced low CSF tigecycline concentrations and failed to achieve a clinical response while on therapy. CSF drug disposition of tigecycline requires further systematic study to fully elucidate the pharmacokinetic profile. Reduced CSF concentrations urge caution in the treatment of cerebritis with standard dosing of tigecycline.