Outcome following postneurosurgical Acinetobacter meningitis: an institutional experience of 72 cases

Ventriculitis due to multidrug-resistant gram-negative bacilli associated with external ventricular drain: evolution, treatment, and outcomes

Introduction

Nosocomial infectious ventriculitis caused by multidrug-resistant (MDR) Gram-negative bacilli associated with external ventricular drainage (EVD) placement poses a significant mortality burden and hospital costs.

Objectives

This study aims to analyze the characteristics, ventriculitis evolution, treatment, and outcomes of patients with ventriculitis due to MDR Gram-negative bacilli associated with EVD placement.

Methods

A retrospective cohort study focusing on patients with nosocomial infection caused by MDR Gram-negative bacilli while on EVD was conducted from 2019 to 2022. Medical, laboratory, and microbiological records were collected. The antibiotic resistance of the Gram-negative bacilli isolated in the cerebrospinal fluid (CSF) of patients was analyzed. The risk factors were identified using univariate risk models and were analyzed using survival curves (Cox regression). An adjusted Cox proportional hazards model was also constructed.

Results

Among 530 patients with suspected EVD-associated ventriculitis, 64 patients with isolation of Gram-negative bacilli in CSF were included. The estimated mortality was 78.12%. Hemorrhages (intracranial, subarachnoid, and intraventricular) were observed in 69.8% of patients. Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa were the most frequently isolated bacilli. In the univariate analysis, significant risk factors for mortality included arterial hypertension, a Glasgow Coma Scale (GCS) score of ≤ 8, invasive mechanical ventilation (IMV) upon hospital admission and during hospitalization, septic shock, and ineffective treatment. The adjusted Cox proportional hazards model revealed that septic shock (HR = 3.3, 95% CI = 1.5-7.2; p = 0.003) and ineffective treatment (HR = 3.2, 1.6-6.5, 0.001) were significant predictors. A high resistance to carbapenems was found for A. baumannii (91.3%) and P. aeruginosa (80.0%). Low resistance to colistin was found for A. baumannii (4.8%) and P. aeruginosa (12.5%).

Conclusion

Ineffective treatment was an independent hazard factor for death in patients with ventriculitis caused by MDR Gram-negative bacilli associated with EVD.

Clinical Characteristics, Treatment, and Outcomes of Veterans with Cerebrospinal Fluid Culture Positive for Gram-Negative Rod Bacteria: A Retrospective Analysis over 18 Years in 125 Veterans Health Administration Hospitals

Optimal management for patients with bacterial ventriculitis/meningitis due to Gram-negative rods (GNRs) has yet to be well investigated. We assessed the clinical characteristics, treatment, and outcomes of patients with a positive cerebrospinal fluid (CSF) culture for GNRs. We conducted a retrospective cohort study of all patients with a positive CSF culture within the Veterans Health Administration (VHA) system during 2003-2020. Clinical and microbiological characteristics between the true meningitis and contamination groups were compared. Of the 5919 patients with positive CSF cultures among 125 nationwide VHA acute-care hospitals, 297 (5.0%) were positive for GNRs. Among 262 patients analyzed, 156 (59.5%) were assessed as patients with true meningitis, and 106 (40.5%) were assessed as patients with contaminated CSF cultures. Patients with true meningitis had a significantly higher CSF protein (median 168 vs 57 mg/dL, p < 0.001), CSF white blood cell count (median 525 vs 3/µL, p = 0.008) and percentage of neutrophils in CSF (median 88 vs 4%, p < 0.001). Enterobacterales were more common in the true meningitis group, while unidentified GNR or polymicrobial CSF cultures were more common in the contamination group. The all-cause 90-day mortality was 25.0% (39/156) in patients with true meningitis and 10.4% (11/106) in those with contaminated CSF cultures. None of the 11 patients with contaminated CSF cultures who died were considered due to missed meningitis. More than 40% of patients with a positive CSF culture with GNR did not receive treatment without negative consequences. Careful clinical judgment is required to decide whether to treat such patients.

Clinical presentations and microbiological analysis of cerebrospinal fluid samples in cases of suspected bacterial meningitis patients attending a 1600 bedded teaching hospital from 2019 to 2022: A retrospective study

Background

Meningitis can be attributed to bacterial, fungal, or viral agents. In this study, we demonstrate the common bacterial agents causing meningitis along with their antibiotics susceptibility pattern in patients of all age groups.

Material and Methods

This retrospective, observational study was carried out in the Department of Microbiology with cerebrospinal fluid (CSF) samples collected from November 2019 to May 2022. We collected 1986 nonrepeat CSF samples from clinically suspected patients of bacterial meningitis, and clinical information about the patients was extracted from the hospital information system.

Results

Out of the 1986 CSF samples included in our study, 150 (7.55%) were found to be positive on bacterial culture. Most of our patients were in the age group of 0-20 years. Common clinical manifestations observed in our patients were: high-grade fever, 87 patients (58%); severe headache, 126 patients (84%); neck rigidity, 47 patients (31.3%); altered mental status, 76 patients (50.7%) and photophobia, 83 patients (55.3%). The most commonly isolated bacteria was Acinetobacter species (30%). The mean length of hospitalization (37.76 ± 25.30), the mean total cell count, high levels of protein (mg/dl) and low levels of glucose (mg/dl) of CSF were statistically significant in meningitis caused by multidrug-resistant bacteria.

Conclusion

We recognized the spectrum of pathogens causing meningitis at our center along with the antibiotic resistance pattern to guide and facilitate early treatment by primary health care professionals and family medicine practitioners.

Bacterial ventriculoperitoneal shunt infections: changing trends in antimicrobial susceptibility, a 7-year retrospective study from Pakistan

BACKGROUND

Ventriculoperitoneal (VP) shunt infections in adults represent a severe complication and make treatment more challenging. Therefore, drug susceptibility patterns are crucial for therapeutic decisions and infection control in neurosurgical centers. This 7-year retrospective study aimed to identify the bacteria responsible for adult VP shunt infections and determine their drug susceptibility patterns.

METHODS

This single-center study was performed from 2015 to 2021 in Lahore, Pakistan, and included CSF cultures from VP shunt infections. Demographic data, causative organisms, and antimicrobial susceptibility testing results were collected. Multivariate analysis of variance (MANOVA) and two-sample t-tests were used to analyze and compare the antibiotic sensitivity trends over the study period.

RESULTS

14,473 isolates recovered from 13,937 CSF samples of VP shunt infections were identified and analyzed for their susceptibility patterns to antimicrobials. The proportion of Gram-negative and Gram-positive bacteria were 11,030 (76%) and 3443 (24)%, respectively. The predominant bacteria were Acinetobacter species (n = 5898, 41%), followed by Pseudomonas species (n = 2368, 16%) and coagulase-negative Staphylococcus (CoNS) (n = 1880, 13%). 100% of Staphylococcus aureus (S.aureus) and CoNS were sensitive to vancomycin and linezolid (n = 2580). However, 52% of S. aureus (719/1,343) were methicillin-resistant Staphylococcus aureus (MRSA). Acinetobacter showed maximum sensitivity to meropenem at 69% (2759/4768). Pseudomonas was 80% (1385/1863 sensitive to piperacillin-tazobactam, Escherichia coli (E. coli) showed 72% to amikacin (748/1055), while Klebsiella spp. was 57% (574/1170) sensitive to piperacillin-tazobactam. The sensitivity of piperacillin-tazobactam and meropenem for Gram-negative bacteria decreased significantly (p < 0.05) over 7 years, with 92.2% and 88.91% sensitive in 2015 and 66.7% and 62.8% sensitive in 2021, respectively.

CONCLUSION

The significant decrease in the effectiveness of carbapenem and beta-lactam/beta-lactamase inhibitor combination drugs for the common Gram-negative causative agents of VP shunt infections suggests that alternative antibiotics such as colistin, fosfomycin, ceftazidime/avibactam, ceftolozane/tazobactam, and tigecycline should be considered and in consequence included in testing panels. Additionally, it is recommended to adopt care bundles for the prevention of VP shunt infection.

Impact of Penicillin Allergy-Based Alternative Antibiotics on the Risk of Postoperative Central Nervous System Infection: A Retrospective Cohort Study

BACKGROUND

Central nervous system (CNS) infection is one of the most serious complications after neurosurgery. This study aimed to analyze the effect of penicillin allergy (PA) and alternative prophylactic antibiotics on risk of postoperative CNS infection in patients undergoing neurosurgery.

METHODS

Data of patients who underwent neurosurgical procedures from January 2015 to December 2021 were analyzed retrospectively. Patients with PA were compared with patients without PA in a 1:1 ratio. A multivariate logistic regression model was used to examine whether PA was a risk factor for postoperative CNS infection.

RESULTS

Overall, 15,049 eligible neurosurgical records were reviewed, from which 578 surgical records of 556 patients with PA were matched to 578 records of 570 patients without PA. Patients with PA showed significantly lower probability to receive prophylactic cephalosporins (55.9% vs. 98.8%, P < 0.01), but significantly higher probability to receive clindamycin (41.86% vs. 1.03%, P < 0.01), than patients without PA. Multivariate analysis revealed that patients with PA were more likely to experience postoperative CNS infection than patients without PA (odds ratio = 2.03; 95% confidence interval, 1.15-3.56; P = 0.014). The incidence of postoperative CNS infection returned to a level comparable to that in general population when patients with suspected PA received prophylactic cephalosporins.

CONCLUSIONS

PA is associated with higher risk of postoperative CNS infection in patients undergoing neurosurgery. This may be attributed to the use of alternative prophylactic antibiotics other than cephalosporins, especially clindamycin.

Bacterial meningitis in children with an abnormal craniocerebral structure

Background

We studied the causative pathogens, clinical characteristics, and outcome of bacterial meningitis in children with an abnormal craniocerebral structure.

Methods

A retrospective single-center study was conducted on children aged in the range of 29 days to 14 years by using data obtained from the pediatric intensive care unit in Shengjing Hospital between January 2014 and August 2021. All children were diagnosed with bacterial meningitis. They were divided into complex and simple groups by taking into account the presence of an abnormal craniocerebral structure before they contracted bacterial meningitis. We collected data on demographics, clinical presentations, laboratory results, imaging studies, treatments, and outcomes.

Results

A total of 207 patients were included in the study (46 in the complex group and 161 in the simple group). Patients in the complex group had a lower mortality rate (6.5% vs. 11.2%, p < 0.05), positive blood culture (13.0% vs. 34.8%; p < 0.05), multiple organ dysfunction syndrome (0% vs. 9.3%; p < 0.05), and shock (2.2% vs. 9.3%; p = 0.11). These patients were more often detected with neurological sequelae (80.4% vs. 53.4%; p < 0.05), cerebrospinal fluid drainage (50% vs. 15.5%; p < 0.05), nosocomial infection (54.3% vs. 3.1%; p < 0.05), and multidrug-resistant bacteria (62.5% vs. 55.6%, p = 0.501). In patients in the simple group, infection was mostly confined to the nervous system.

Conclusion

Bacterial meningitis patients with an abnormal craniocerebral structure had fewer bloodstream infections, lower mortality rates, and higher incidence rates of neurological sequelae. Pathogens were more likely to be nosocomial and multidrug-resistant bacteria.

Risk factors for 90-day all-cause mortality in post-operative central nervous system infections (PCNSIs): A retrospective study of 99 patients in China

Post-operative central nervous system infections (PCNSIs) are serious complications of craniotomy. Many factors, including patient-related, surgical, and postoperative factors, affect the survival of patients with PCNSIs. Timely and effective implementation of antibiotics targeting pathogenic bacteria is crucial to reduce mortality. Metagenomic next-generation sequencing (mNGS) has been used successfully to detect pathogens associated with infectious diseases. This study was designed to evaluate the factors influencing mortality and to explore the application value of mNGS in patients with PCNSIs. We conducted a retrospective study of patients with PCNSIs in our unit from 1/12/2019 to 28/2/2021. Clinical data, cerebrospinal fluid (CSF) parameters, surgical information, and mNGS results were collected. Follow-up telephone calls were made in June 2021 for 90 days survival after discharge. 99 patients were enrolled, and the overall mortality rate was 36.4% (36/99). Kaplan-Meier survival analysis suggested that the risk factors for poor prognosis included age ≥ 53 years, Glasgow Coma scale (GCS) score ≤ 8, CSF/blood glucose ratio (C/B-Glu) ≤ 0.23, 2 or more operations, mechanical ventilation (MV), and non-mNGS test. MV and poor wound healing were independent risk factors for 90 day mortality according to the multivariate Cox proportional hazards model (OR = 6.136, P = .017, OR = 2.260, P = .035, respectively). Among the enrolled patients, causative pathogens were identified in 37. Gram-negative pathogens were found in 22 (59.5%) patients, and the remaining 15 (40.5%) were Gram-positive pathogens. Univariate analysis showed that white cell count and protein and lactate levels in the CSF of the Gram-negative group were higher than those of the Gram-positive group (P < .05). mNGS and conventional microbiological culture were tested in 34 patients, and the positive detection rate of mNGS was 52.9%, which was significantly higher than that of microbiological culture (52.9% vs 26.5%, χ2 = 4.54, P = .033). The mortality rate of PCNSIs is high, and patients with MV and poor wound healing have a higher mortality risk. Gram-negative pathogens were the predominant pathogens in the patients with PCNSIs. mNGS testing has higher sensitivity and has the potential to reduce the risk of mortality in patients with PCNSIs.

Nomogram Analysis of Clinical Characteristics and Mortality Risk Factor of Non-Fermentative Gram-Negative Bacteria-Induced Post-Neurosurgical Meningitis

Objective

To explore the clinical characteristics of post-neurosurgical meningitis (PNM) patients infected with nonfermenting Gram-negative bacilli (NFGNB) and to evaluate the related mortality risk factors.

Methods

A cohort analysis of PNM patients infected with NFGNB in Beijing Tiantan Hospital and Capital Medical University from 2012.1 to 2020.12. The microbial distribution, antimicrobial sensitivity and genotypes were tested, and potential mortality risk factors were evaluated using Mann–Whitney U or chi-squared tests. Independent risk factors for mortality were established by constructing a logistic model.

Results

A total of 2940 PNM patients were enrolled in this study, of whom 207 (17.1%) were infected with NFGNB. Among these patients, 29 died of NFGNB meningitis, with an overall mortality rate of 14.0%. The top three NFGNBs were Acinetobacter baumannii (105 cases, 50.7%), Pseudomonas aeruginosa (29 cases, 14.0%) and Acinetobacter lwoffii (20 cases, 9.7%). Nomogram analysis revealed that hypertension (OR 4.551, 95% CI: 1.464–14.154, P = 0.009), external ventricular drainage (EVD) (OR 3.944, 95% CI: 1.286–12.095, P = 0.016), and assisted mechanical ventilator (AMV) (OR 6.192, 95% CI: 1.737–22.081, P = 0.005) were independent risk factors for mortality. In addition, antibiotic prophylaxis was shown to play a vital role in NFGNB-induced PNM therapy.

Conclusion

PNM patients infected with NFGNB have a high mortality rate. Hypertension, EVD and AMV were independent mortality risk factors, and clinical attention should be paid to their prevention and treatment.

Acinetobacter baumannii Biofilm Formation: Association with Antimicrobial Resistance and Prolonged Survival under Desiccation

Biofilm-forming multidrug-resistant Acinetobacter baumannii has emerged as a global pathogen. This study investigated the impact of biofilm formation by A. baumannii on antimicrobial resistance and prolonged survival under desiccation, which is essential for effective infection control of A. baumannii in hospital settings. Seventy-eight clinical isolates of A. baumannii were identified, and antibiotic susceptibility profiles were assessed. All the isolates were investigated for their biofilm-forming abilities at 24 and 48 h. The biofilm inhibitory concentrations of antibiotics were evaluated for selected biofilm-forming isolates to determine the influence of biofilm on antibiotic tolerance. The impact of biofilm formation on desiccation tolerance was also evaluated for up to 48 days. The results revealed that out of 78 A. baumannii clinical isolates, 83% were MDR and 17% non-MDR. Overall, 79% of isolates formed high biofilm after 24 h. The extent of biofilm formation gets significantly increased after 48 h, and 87% of isolates formed high biofilm. It was observed that eradicating mature biofilm requires up to a thousandfold higher concentration of antibiotics than MICs, and biofilm-forming isolates can survive for a prolonged period under desiccation. In conclusion, our findings revealed that both MDR and non-MDR isolates of A. baumannii could form biofilms on abiotic surfaces. A. baumannii biofilms contribute to endurance in the presence of antimicrobials and desiccation conditions, which are significant trouble for hospital patient care management. The present findings may offer insights for developing preventive measures to tackle biofilm-associated A. baumannii infection.

Polymyxin B, Cefoperazone Sodium-Sulbactam Sodium, and Tigecycline against Multidrug-Resistant Acinetobacter baumannii Pneumonia

Purpose

The purpose of this study is to investigate the significance of polymyxin B in combination with cefoperazone sodium-sulbactam sodium (CSSS) and tigecycline for the treatment of multidrug-resistant Acinetobacter baumannii- (MDRAB-) induced pneumonia on the levels of white blood cell (WBC) count, serum C-reactive protein (CRP), and procalcitonin (PCT).

Methods

Fifty-six patients with MDRAB pneumonia admitted to the Fifth People's Hospital of Wuhu from February 2019 to December 2021 were randomized into the observation group (n = 28) and the experimental group (n = 28) by the random table method. The observation group received intravenous infusion of CSSS and tigecycline. The experimental group received intravenous infusion of polymyxin B sulfate plus CSSS and tigecycline. All patients were treated for 14 days.

Results

There was no significant difference in the overall response rate between the two groups; the bacterial clearance of the experimental group was significantly higher than that of the observation group; there was no significant difference in the WBC, CRP, and PCT levels between the two groups prior to the treatment; but after treatment, while the WBC, CRP, and PCT levels of the two groups decreased, the WBC count, CRP, and PCT levels of the experimental group were significantly lower than those of the observation group; no significant difference was found in adverse reactions.

Conclusion

Polymyxin B-CSSS-tigecycline has good clinical efficacy in the treatment of MDRAB pneumonia. It not only improves the patients' bacterial clearance rate and effectively reduces the levels of WBC count, serum CRP, and PCT, but also raises no risk of adverse reactions. Therefore, it is worthy of clinical promotion.

Accuracy of heparin-binding protein for the diagnosis of nosocomial meningitis and ventriculitis

Background

The sensitive and accurate diagnosis of nosocomial meningitis and ventriculitis is still a critical problem. This study was designed to explore the diagnostic value of cerebrospinal fluid heparin-binding protein (HBP) in nosocomial meningitis and ventriculitis in comparison with procalcitonin and lactate.

Methods

In this observational study, 323 suspected patients were enrolled, of which 42 participants were excluded because they could not be accurately grouped, 131 subjects who were eventually diagnosed with nosocomial meningitis or ventriculitis and 150 patients in whom infection was ultimately ruled out were included in the final analysis. The main results are expressed as medians (interquartile ranges). The Chi-squared test was used to compare the baseline characteristics. The Mann–Whitney U-test was used for group and subgroup analyses. The area under the receiver operating characteristic curve was calculated to describe the diagnostic accuracy of the biomarkers. Spearman's partial correlation was used to analyze associations between the biomarkers. Statistical significance was set when p value < 0.05.

Results

HBP achieved the largest area under the receiver operating characteristic curve, which was 0.99 (95% confidence interval 0.98—1.00) compared with 0.98 (95% confidence interval 0.96—0.99) for lactate and 0.69 (95% confidence interval 0.62—0.75) for procalcitonin. With a cutoff level at 23 ng/mL, HBP achieved a sensitivity of 97%, a specificity of 95%, a positive predictive value of 93% and a negative predictive value of 98%. The levels of HBP presented no significant discrepancy between patients who received previous empiric anti-infective therapy and those who did not (p > 0.05). Higher concentrations of HBP were present in patients with positive microbiological findings (p < 0.05). Levels of HBP positively correlated with polymorphonuclear cell count (Spearman's rho = 0.68, p < 0.01), white blood cell count (Spearman's rho = 0.57, p < 0.01) and lactate (Spearman's rho = 0.34, p < 0.01).

Conclusions

Cerebrospinal fluid heparin-binding protein is a reliable auxiliary diagnostic marker that is preferable over lactate and procalcitonin in identifying nosocomial meningitis and ventriculitis, and it also contributes to solving the diagnostic difficulties caused by empiric antibiotherapy.

Infections Due to Acinetobacter baumannii-calcoaceticus Complex: Escalation of Antimicrobial Resistance and Evolving Treatment Options

Bacteria within the genus Acinetobacter (principally A. baumannii-calcoaceticus complex [ABC]) are gram-negative coccobacilli that most often cause infections in nosocomial settings. Community-acquired infections are rare, but may occur in patients with comorbidities, advanced age, diabetes mellitus, chronic lung or renal disease, malignancy, or impaired immunity. Most common sites of infections include blood stream, skin/soft-tissue/surgical wounds, ventilator-associated pneumonia, orthopaedic or neurosurgical procedures, and urinary tract. Acinetobacter species are intrinsically resistant to multiple antimicrobials, and have a remarkable ability to acquire new resistance determinants via plasmids, transposons, integrons, and resistance islands. Since the 1990s, antimicrobial resistance (AMR) has escalated dramatically among ABC. Global spread of multidrug-resistant (MDR)-ABC strains reflects dissemination of a few clones between hospitals, geographic regions, and continents; excessive antibiotic use amplifies this spread. Many isolates are resistant to all antimicrobials except colistimethate sodium and tetracyclines (minocycline or tigecycline); some infections are untreatable with existing antimicrobial agents. AMR poses a serious threat to effectively treat or prevent ABC infections. Strategies to curtail environmental colonization with MDR-ABC require aggressive infection-control efforts and cohorting of infected patients. Thoughtful antibiotic strategies are essential to limit the spread of MDR-ABC. Optimal therapy will likely require combination antimicrobial therapy with existing antibiotics as well as development of novel antibiotic classes.

Current Perspectives on the Diagnosis and Management of Healthcare-Associated Ventriculitis and Meningitis

Ventriculitis or post-neurosurgical meningitis or healthcare-associated ventriculitis and meningitis (VM) is a severe infection that complicates central nervous system operations or is related to the use of neurosurgical devices or drainage catheters. It can further deteriorate patients who have already presented significant neurologic injury and is associated with high morbidity, mortality, and poor functional outcome. VM can be difficult to distinguish from aseptic meningitis, inflammation that follows hemorrhagic strokes and neurosurgical operations. The associated microorganisms can be either skin flora or nosocomial pathogens, most commonly, Gram-negative bacteria. Classical microbiology can fail to isolate the culprit pathogen. Novel cerebrospinal fluid (CSF) biomarkers and molecular microbiology can fill the diagnostic gap and expedite pathogen identification and treatment. The pathogens may demonstrate significant resistant patterns and their antibiotic treatment can be difficult, as many important drug classes, including the beta-lactams and the glycopeptides, hardly penetrate to the CSF, and do not achieve therapeutic levels at the site of the infection. Treatment modifications, such as higher daily dose and prolonged or continuous administration, might increase antibiotic levels in the site of infection and facilitate pathogens clearance. However, in the case of therapeutic failure or infection due to difficult-to-treat bacteria, the direct antibiotic instillation into the CSF, in addition to the intravenous antibiotic delivery, may help in the resolution of infection. However, intraventricular antibiotic therapy may result in aseptic meningitis and seizures, concerning the administration of aminoglycosides, polymyxins, and vancomycin. Meanwhile, bacteria form biofilms on the catheter or the device that should routinely be removed. Novel neurosurgical treatment modalities comprise endoscopic evacuation of debris and irrigation of the ventricles. VM prevention includes perioperative antibiotics, antimicrobial impregnated catheters, and the implementation of standardized protocols, regarding catheter insertion and manipulation.

Antimicrobial use in central nervous system infections

PURPOSE OF REVIEW

Central nervous system (CNS) infections are associated with high rates of morbidity and mortality. The purpose of this review is to summarize current antimicrobial therapies, as well as, updates in the management of community-acquired meningitis and healthcare-associated meningitis and ventriculitis.

RECENT FINDINGS

Due to the increasing rates of multidrug resistant and extensively-drug resistant organisms, available antimicrobials are limited. Novel treatment options include newer systemic antimicrobials and antimicrobials that have previously limited data in the management of CNS infections. Although limited by retrospective data, intrathecal (IT) and intraventricular (IVT) routes of administration offer the opportunity for antimicrobials that conventionally have minimal cerebrospinal fluid (CSF) penetration to achieve high CSF concentrations while minimizing systemic exposure.

SUMMARY

Updates in the use of systemic, IT, and IVT antimicrobials offer promise as therapeutic options for CNS infections. Additional pharmacokinetic and prospective data are needed to confirm these findings.

Epidemiology of patients with central nervous system infections, mainly neurosurgical patients: a retrospective study from 2012 to 2019 in a teaching hospital in China

BACKGROUND

Central nervous system (CNS) infections are relatively rare but are associated with high mortality worldwide. Empirical antimicrobial therapy is crucial for the survival of patients with CNS infections, and should be based on the knowledge of the pathogen distribution and antibiotic sensitivities. The aim of this study was to investigate the features of pathogens in patients with CNS infections in North China and evaluate the risk factors for mortality and multi-drug-resistant (MDR) bacterial infections.

METHODS

A retrospective study was conducted with patients with positive cerebrospinal fluid (CSF) cultures in a teaching hospital from January 2012 to December 2019. The following data were collected: demographic characteristics, laboratory data, causative organisms and antimicrobial sensitivity results. Data were analyzed with SPSS 16.0. Univariate analysis and binary logistic regression analyses were performed to identify the risk factors for mortality and MDR bacterial infections.

RESULTS

A total of 72 patients were diagnosed with CNS infections, and 86 isolates were identified. The proportions of Gram-positive bacteria, Gram-negative bacteria and fungi were 59.3, 30.2 and 10.5%, respectively. The predominant Gram-positive bacteria was Coagulase-negative Staphylococci. Acinetobacter baumannii, Escherichia coli and Klebsiella spp. were the predominant Gram-negative bacteria. Compared to 2012-2015 years, the proportion of Gram-negative bacteria increased markedly during 2016-2019 years. Coagulase-negative Staphylococci, Streptococcus pneumoniae and Enterococcus faecium had 100% sensitivity to vancomycin, teicoplanin and linezolid. Acinetobacter baumannii and Klebsiella pneumoniae were 100% sensitive to tigecycline. Escherichia coli had 100% sensitivity to amikacin, meropenem and imipenem. The overall mortality rate in the 72 patients was 30.6%. In multivariate analysis, age > 50 years, pulmonary infections and CSF glucose level < the normal value were associated with poor outcomes. CSF adenosine deaminase level > the normal value and the presence of external ventricular drainage/lumbar cistern drainage were associated with MDR bacterial infections.

CONCLUSIONS

The mortality rate due to CNS infections reached 30.6% in our study. The proportion of Gram-negative bacteria has increased markedly in recent years. We should give particular attention to patients with risk factors for mortality and MDR bacterial infections mentioned above.

Ventriculitis: A Severe Complication of Central Nervous System Infections

BACKGROUND

Ventriculitis, a dreaded complication of brain abscess, meningitis, and various neurosurgical procedures, has attracted limited attention in the medical literature.

METHODS

This is a retrospective, single-center study. We screened the medical files of all patients who had a brain imaging report that included the word "ventriculitis" during years 2005-2019. Only patients with clinical, microbiological, and imaging features of ventriculitis were included. Data were collected through a standardized questionnaire.

RESULTS

Ninety-eight patients fulfilled inclusion criteria: 42 women and 56 men, and the median age was 60 years (interquartile range, 48-68). The primary mechanism for ventriculitis was classified as follows: brain abscess (n = 29, 29.6%), meningitis (n = 27, 27.6%), intraventricular catheter-related (n = 17, 17.3%), post-neurosurgery (n = 13, 13.3%), and hematogenous (n = 12, 12.2%). The main neuroimaging features were intraventricular pus (n = 81, 82.7%), ependymal enhancement (n = 70, 71.4%), and intraventricular loculations (n = 15, 15.3%). The main pathogens were streptococci (n = 44, 44.9%), Gram-negative bacilli (n = 27, 27.6%), and staphylococci (n = 15, 15.3%). In-hospital and 1-year mortality rates were 30.6% (n = 30) and 38.8% (n = 38), respectively. Neurological sequelae were reported in 34 of 55 (61.8%) survivors, including cognitive impairment (n = 11), gait disturbances (n = 9), paresis (n = 7), behavior disorder (n = 6), and epilepsy (n = 5). On multivariate analysis, age >65 years, Glasgow Coma Scale score <13 at initial presentation, status epilepticus, hydrocephalus, and positive cerebrospinal fluid culture were associated with 1-year mortality. We built a scoring system to stratify patients with ventriculitis into low risk (12.5%), intermediate risk (36.5%), and high risk (71.4%) of death.

CONCLUSIONS

Ventriculitis is a severe complication of brain abscess, meningitis, or neurosurgery, with an in-hospital mortality rate of 30% and neurological sequelae in 60% of survivors.

Phenotypic and WGS-derived antimicrobial resistance profiles of clinical and non-clinical Acinetobacter baumannii isolates from Germany and Vietnam

OBJECTIVES

This study aimed to combine in vitro phenotyping analysis and whole-genome-sequencing (WGS) to characterise the phenotype and genetic determinants associated with intrinsic resistance in 100 clinical and non-clinical Acinetobacter baumannii strains originating from Germany and Vietnam. Moreover, it aimed to assess whether powdered milk as a food source functions as a potential reservoir of antibiotic resistance and possesses similar antimicrobial resistance (AMR) genes as in clinical strains isolated from Germany.

METHODS

Antimicrobial susceptibility testing was performed using the broth microdilution method and the minimum inhibitory concentration (MIC) was determined for 18 antibiotics. The WGS data from all isolates were mapped to intrinsic genes known to be associated with phenotypic AMR.

RESULTS

The highest resistance frequency was observed for chloramphenicol (100%), followed by fosfomycin (96%) and cefotaxime (95%). The lowest resistant rates were observed for colistin (3%), trimethoprim/sulfamethoxazole (17%), tigecycline (19%), and amikacin (19%). Thirty-five percent of tested strains displayed resistance to at least one of the carbapenems. Resistance to fluoroquinolones, aminoglycosides, tigecycline, penicillins, trimethoprim/sulfamethoxazole, and fourth-generation cephalosporins was determined only in human strains. About one-quarter of isolates (24%) was multidrug-resistant (MDR) and all were of human origin. Among them, 16 isolates were extensively drug resistant (XDR) and 10 from those 16 isolates showed resistance to all tested antibiotics except colistin. In silico detection of intrinsic AMR genes revealed the presence of 36 β-lactamases and 24 non-β-lactamase resistance genes. Two colistin-resistant and 10 ertapenem-resistant strains were isolated from powdered milk produced in Germany. Thirty-eight AMR genes associated with resistance to antibiotics were found in isolates recovered from milk powder. Several resistance mechanisms towards many classes of antibiotics existed in A. baumannii including β-lactamases, multidrug efflux pumps and aminoglycoside-modifying enzymes.

CONCLUSION

The use of WGS for routine public health surveillance is a reliable method for the rapid detection of emerging AMR in A. baumannii isolates. Milk powder poses a risk to contain MDR Acinetobacter strains or resistance genes in Germany.

Longitudinal Analysis of Risk Factors for Clinical Outcomes of Enterobacteriaceae Meningitis/Encephalitis in Post-Neurosurgical Patients: A Comparative Cohort Study During 2014-2019

Purpose

Our study is a retrospective observational study conducted in one of the largest clinical centers of neurosurgery in China. We aimed to investigate the antimicrobial susceptibility patterns of the Enterobacteriaceae isolates responsible for nosocomial meningitis/encephalitis in post-neurosurgical patients. Meanwhile, we tried to evaluate the risk factors for mortality following Enterobacteriaceae meningitis/encephalitis.

Patients and Methods

Medical data on clinical characteristics, antibiotic susceptibilities, and mortality were reviewed until patients’ discharge or death in the hospital. Data for a total of 164 cerebrospinal fluid (CSF) infection cases due to Enterobacteriaceae after neurosurgery were collected between January 2014 and November 2019 in order to identify risk factors affecting the outcome. Kaplan–Meier survival analysis and multivariable Cox proportional hazard models were applied.

Results

In this study, a total of 2416 neurosurgical meningitis/encephalitis cases were reported between 2014 and 2019. Enterobacteriaceae accounted for 7.3% (176/2416) of all the bacterial infections. Of them, 164 Enterobacteriaceae isolates were available to divide into two groups according to the final outcome of whether the patient died or survived. In total, 38 patients died (23.2%) and 126 patients survived (76.8%). The most frequent infecting species was Klebsiella pneumoniae (47.0%, 77/164). Fourteen-day and 30-day mortality rates were 7.9% (13/164) and 15.2% (25/164). Kaplan–Meier survival analysis revealed that the risk factors of Enterobacteriaceae meningitis/encephalitis that resulted in poor outcomes included comorbidities, Glasgow Coma Scale (GCS) score, sepsis, intensive care unit (ICU) admission, extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, and ventilation. A GCS score of less than or equal to 8 (P=0.04, HR 2.562) was identified to be a significant risk factor for mortality according to the multivariable Cox proportional hazards model.

Conclusion

In-hospital mortality caused by Enterobacteriaceae meningitis/encephalitis in neurosurgery was high. A GCS score of ≤8 was an independent risk factor for mortality following Enterobacteriaceae meningitis/encephalitis in post-neurosurgical patients.

Insights into Acinetobacter baumannii: A Review of Microbiological, Virulence, and Resistance Traits in a Threatening Nosocomial Pathogen

Being a multidrug-resistant and an invasive pathogen, Acinetobacter baumannii is one of the major causes of nosocomial infections in the current healthcare system. It has been recognized as an agent of pneumonia, septicemia, meningitis, urinary tract and wound infections, and is associated with high mortality. Pathogenesis in A. baumannii infections is an outcome of multiple virulence factors, including porins, capsules, and cell wall lipopolysaccharide, enzymes, biofilm production, motility, and iron-acquisition systems, among others. Such virulence factors help the organism to resist stressful environmental conditions and enable development of severe infections. Parallel to increased prevalence of infections caused by A. baumannii, challenging and diverse resistance mechanisms in this pathogen are well recognized, with major classes of antibiotics becoming minimally effective. Through a wide array of antibiotic-hydrolyzing enzymes, efflux pump changes, impermeability, and antibiotic target mutations, A. baumannii models a unique ability to maintain a multidrug-resistant phenotype, further complicating treatment. Understanding mechanisms behind diseases, virulence, and resistance acquisition are central to infectious disease knowledge about A. baumannii. The aims of this review are to highlight infections and disease-producing factors in A. baumannii and to touch base on mechanisms of resistance to various antibiotic classes.