Microbiology and Treatment of Cerebrospinal Fluid Shunt Infections in Children

Implementation of an adapted perioperative ventriculoperitoneal shunting protocol in a tertiary center located in a low-to-middle-income country

OBJECTIVE

Preventative protocols have efficaciously reduced shunt infection in developed countries. However, the generalizability of these protocols in low-to-middle-income countries (LMICs) remains unclear. Previously, shunt insertion in the authors' center was routinely performed under institutional preventative precautions, which was updated via merging with the Hydrocephalus Clinical Research Network (HCRN) protocol. This study aimed to investigate the ventriculoperitoneal shunt (VPS) infection rates in pediatric patients following the implementation of the adapted protocol.

METHODS

The adapted protocol was implemented in all first-time VPS implantations between 2011 and 2021. The primary outcome was a 6-month shunt infection. The Pearson chi-square test was used for categorical variables and the Mann-Whitney U-test for numeric variables to evaluate the correlation with shunt infection.

RESULTS

A total of 352 first-time VPS procedures were performed adhering to the adapted protocol. The median age was 5 months, and 189 (53.7%) were male. Overall, 37 patients (10.5%) experienced shunt infection, with 30 (8.5%) occurring within the first 6 months, which was lower than 13.3% infection rate of the previous series of the same center. The infection rate was slightly higher than the 5.7% and 6.0% rates reported by HCRN studies. Patients with shunt infection were significantly younger (7.5 versus 17.5 months, P < 0.001).

CONCLUSIONS

This study validates the efficacy of an adapted perioperative protocol in mitigating shunt infection in a high-volume center in a LMIC. Adhering to a step-by-step protocol, modified to suit the healthcare resources and financial constraints of LMICs, could maintain low shunt infection rates that are roughly comparable to those of centers in high-income countries.

Cerebrospinal Fluid Shunt Reinfection and Malfunction in Ecuadorian Children with Different Reshunting Criteria After Infection. "Is It Just One Shunt After Another?"

OBJECTIVE

There is no firm evidence regarding cerebrospinal fluid (CSF) shunt reimplantation after infection in the pediatric population. The purpose of this study was to compare different criteria and analyze new shunt failure.

METHODS

A cross-sectional retrospective multicenter study was performed over 6 years to study patients and each infected shunt at diagnosis, reimplantation, and after reimplantation. The patients were divided into 2 groups: group 1 (G1), reimplantation after negative serial CSF cultures during antibiotic treatment; group 2 (G2), reimplantation after negative serial pancultures after completion of antibiotics. The differences were measured with Mann-Whitney and Χ2 tests; multivariate analysis and associations were calculated using odds ratios (ORs) based on logistic regression.

RESULTS

There were 137 shunt infection events in 110 patients: 28 events in G1 and 109 in G2. Significant differences were observed in the diagnosis and reimplantation. Reimplantation dysfunction in G1 was 16 (55.17%) versus 30 (27.78%) in G2 (P = 0.006). The risk of shunt malfunction after reimplantation increased for G1 reimplantation criteria (P = 0.018; OR, 3.34; confidence interval [CI], 1.23-9.05): pleocytosis at diagnosis >17 cells (P = 0.036; OR, 2.41; CI, 1.06-5.47), CSF proteins at diagnosis >182 mg/dL (P = 0.049; OR, 2.21; CI, 1.00-4.89).

CONCLUSIONS

G2 reimplantation criteria were related to improved pleocytosis, CSF proteins, and blood neutrophils compared with G1. Mechanical and infectious dysfunction of the new shunt was 3 times more prevalent in G1 than in G2, considering the differences between the groups at diagnosis. Increased parameters of infection at diagnosis were associated with future malfunction more than parameters before reimplantation in both groups.

Associations of Standard Care, Intrathecal Antibiotics, and Antibiotic-Impregnated Catheters With Cerebrospinal Fluid Shunt Infection Organisms and Resistance

BACKGROUND

Infection prevention techniques used during cerebrospinal fluid (CSF) shunt surgery include: (1) standard perioperative intravenous antibiotics, (2) intrathecal (IT) antibiotics, (3) antibiotic-impregnated catheter (AIC) shunt tubing, or (4) Both IT and AIC. These techniques have not been assessed against one another for their impact on the infecting organisms and patterns of antimicrobial resistance.

METHODS

We performed a retrospective longitudinal observational cohort study of children with initial CSF shunt placement between January 2007 and December 2012 at 6 US hospitals. Data were collected electronically from the Pediatric Health Information Systems+ (PHIS+) database, and augmented with standardized chart review. Only subjects with positive CSF cultures were included in this study.

RESULTS

Of 1,723 children whose initial shunt placement occurred during the study period, 196 (11%) developed infection, with 157 (80%) having positive CSF cultures. Of these 157 subjects, 69 (44%) received standard care, 28 (18%) received AIC, 55 (35%) received IT antibiotics, and 5 (3%) received Both at the preceding surgery. The most common organisms involved in monomicrobial infections were Staphylococcus aureus (38, 24%), coagulase-negative staphylococci (36, 23%), and Cutibacterium acnes (6, 4%). Compared with standard care, the other infection prevention techniques were not significantly associated with changes to infecting organisms; AIC was associated with decreased odds of methicillin resistance among coagulase-negative staphylococci.

CONCLUSIONS

Because no association was found between infection prevention technique and infecting organisms when compared to standard care, other considerations such as tolerability, availability, and cost should inform decisions about infection prevention during CSF shunt placement surgery.

Cerebrospinal fluid shunt infections in children

Cerebrospinal fluid (CSF) shunts are commonly used for the long-term management of hydrocephalus in children. Shunt infection remains a common complication, occurring in about 5%-15% of CSF shunts. This narrative review summarises key evidence from recent literature on the epidemiology, pathogenesis, clinical presentation, diagnosis, management, outcomes and prevention of CSF shunt infections in children. The majority of shunt infections occur due to contamination at the time of surgery, with coagulase-negative staphylococci and Staphylococcus aureus being the most common infecting organisms. Clinical presentations of shunt infection can be varied and difficult to recognise. CSF cultures are the primary test used for diagnosis. Other CSF and blood parameters may aid in diagnosis but lack sensitivity and specificity. Core aspects of management of shunt infections include systemic antimicrobial therapy and surgical removal of the shunt. However, many specific treatment recommendations are limited by a lack of robust evidence from large studies or controlled trials. Shunt infections may result in long hospital stays, worsening hydrocephalus, neurological sequelae and other complications, as well as death. Therefore, reducing the incidence of infection and optimising management are high priorities. Antibiotic prophylaxis at the time of shunt placement, improved surgical protocols and antibiotic-impregnated shunts are key strategies to prevent shunt infections. Nevertheless, further work is needed to identify additional strategies to prevent complications and improve outcomes.

Prevention of device-related infections in patients with cancer: Current practice and future horizons

Over the past several years, multifaceted advances in the management of cancer have led to a significant improvement in survival rates. Throughout patients' oncological journeys, they will likely receive one or more implantable devices for the administration of fluids and medications as well as management of various comorbidities and complications related to cancer therapy. Infections associated with these devices are frequent and complex, often necessitating device removal, increasing health care costs, negatively affecting quality of life, and complicating oncological care, usually leading to delays in further life-saving cancer therapy. Herein, the authors comprehensively review multiple evidence-based recommendations along with best practices, expert opinions, and novel approaches for the prevention of diverse device-related infections. The authors present many general principles for the prevention of these infections followed by specific device-related recommendations in a systematic manner. The continuous involvement and meaningful cooperation between regulatory entities, industry, specialty medical societies, hospitals, and infection control-targeted interventions, along with primary care and consulting health care providers, are all vital for the sustained reduction in the incidence of these preventable infections.

The collagen matrix dural substitute graft prevents postoperative cerebrospinal fluid leakage after ventriculoperitoneal shunt surgery in patients aged <1 year

Background:

Cerebrospinal fluid (CSF) leakage is a common complication of ventriculoperitoneal shunt (VPS) and has the potential to induce shunt infection. Especially in infants and children, these are serious complications. DuraGen is a collagen matrix dural substitute used to reduce the risk of CSF leakage in various neurosurgeries. We report our VPS procedure with DuraGen for preventing postoperative CSF leakage in patients aged <1 year.

Methods:

We used DuraGen to prevent postoperative CSF leakage in six VPS surgeries. Antibiotic-impregnated shunt catheters and programmable valves with anti-siphon devices were also used in all cases. DuraGen was placed inside and atop the burr hole. All cases had an initial shunt pressure of 5 cmH2O. Fibrin glue was not used.

Results:

The patients underwent follow-up for a year after VPS surgery. There was no postoperative subcutaneous CSF collection or leakage after all six VPS surgeries. Furthermore, no postoperative shunt infections or DuraGen-induced adverse events were noted.

Conclusion:

We speculate that DuraGen has a preventive effect on postoperative CSF leakage in VPS cases aged <1 year.

Cerebrospinal Fluid System Infection in Children with Cancer: A Retrospective Analysis over 14 Years in a Major European Pediatric Cancer Center

Infection of a cerebrospinal fluid system is a serious medical complication. We performed a retrospective monocentric analysis on temporary and permanent cerebrospinal fluid devices in children with and without cancer, covering a period of over 14 years. Between 2004 and 2017, 275 children with a cerebrospinal fluid system were seen at our institution. Thirty-eight children suffered from 51 microbiologically proven infectious episodes of the cerebrospinal fluid system (12 children with cancer and 26 children without cancer). Independently of the cerebrospinal fluid system used, the incidence of infection did not significantly differ between children with and without cancer and was the highest in children younger than one year. Infection occurred earlier in external ventricular drain (EVD) than ventriculoperitoneal (VP) shunt, and in EVD significantly earlier in children with cancer compared with patients without cancer. The pathogens isolated were mainly Gram-positive bacteria, in particular Staphylococcus spp., which should be taken into account for empirical antimicrobial therapy.

Systematic Review and Meta-Analysis of Antibiotic-Impregnated Shunt Catheters on Anti-Infective Effect of Hydrocephalus Shunt

OBJECTIVE

Shunt infection is a common complication while treating hydrocephalus. The antibiotic-impregnated shunt catheter (AISC) was designed to reduce shunt infection rate. A meta-analysis was conducted to study the effectiveness of AISCs in reduction of shunt infection in terms of age, follow-up time and high-risk patient population.

METHODS

This study reviewed literature from three databases including PubMed, EMBASE, and Cochrane Library (from 2000 to March 2019). Clinical studies from controlled trials for shunt operation were included in this analysis. A subgroup analysis was performed based on the patient's age, follow-up time and high-risk population. The fixed effect in RevMan 5.3 software (Cochrane Collaboration) was used for this meta-analysis.

RESULTS

This study included 19 controlled clinical trials including 10105 operations. The analysis demonstrated that AISC could reduce the infection rate in shunt surgery compared to standard shunt catheter (non-AISC) from 8.13% to 4.09% (odds ratio [OR], 0.48; 95% confidence interval [CI], 0.40-0.58; p=0.01; I2=46%). Subgroup analysis of different age groups showed that AISC had significant antimicrobial effects in all three groups (adult, infant, and adolescent). Follow-up time analysis showed that AISC was effective in preventing early shunt infections (within 6 months after implant). AISC is more effective in high-risk population (OR, 0.24; 95% CI, 0.14-0.40; p=0.60; I2=0%) than in general patient population.

CONCLUSION

The results of meta-analysis indicated that AISC is an effective method for reducing shunt infection. We recommend that AISC should be considered for use in infants and high-risk groups. For adult patients, the choice for AISC could be determined based on the treatment cost.

Recurrent Shoulder Tip Pain After Ventriculoperitoneal Shunt Placement Associated with Infectious Peritonitis with Propionibacterium acnes; A Case Report and Review of the Literature

Ventriculoperitoneal (VP) shunt placement is commonly performed for the treatment of hydrocephalus, and several complications of this procedure are well known. Radiating shoulder tip pain after VP shunt placement has been reported as an unusual complication in a few cases, associated with dislocation of the peritoneal catheter. We described the case of a 9-year-old girl who presented with recurrent radiating shoulder tip pain after VP shunt placement. The pain recurred after peritoneal catheter repositioning because of peritoneal inflammation and adhesion due to peritonitis with Propionibacterium acnes (P. acnes). This bacterium was isolated using 16S ribosomal RNA gene polymerase chain reaction (16S rRNA gene PCR), and anaerobic and prolonged culture tests. After antibacterial treatment, ventriculoarterial (VA) shunt placement was successfully performed. Hemidiaphragm irritation by the peritoneal catheter leads to radiating shoulder tip pain, and peritoneal inflammation and adhesion caused by infectious peritonitis may cause recurrence of this despite catheter repositioning. Clinicians should be aware of shoulder pain as a complication of VP shunt placement, and should consider VA shunt placement as an alternative treatment if this symptom recurs after catheter repositioning. Furthermore, 16S rRNA gene PCR and anaerobic and prolonged culture tests should be considered to detect P. acnes infection.

Ceftaroline Cerebrospinal Fluid Penetration in the Treatment of a Ventriculopleural Shunt Infection: A Case Report

Pharmacokinetic data regarding ceftaroline fosamil (CPT) penetration into cerebrospinal fluid (CSF) are limited to a rabbit model (15% inflamed) and adult case reports. We describe serum and CSF CPT concentrations in a 21-year-old, 34.8 kg female, medically complex patient presented with a 4-day history of fevers (Tmax 39.2°C), tachypnea, tachycardia, fatigue, and a 1-week history of pus and blood draining from the ventriculopleural (VPL) shunt. A head CT and an ultrasound of the neck revealed septated complex fluid collection surrounding the shunt. Therapy was initiated with vancomycin and ceftriaxone. Blood and CSF cultures from hospital day (HD) 1 were positive for methicillin-resistant Staphylococcus aureus with a CPT MIC of 0.5 mg/L and a vancomycin MIC range of 0.5 to 1 mg/L. On HD 3, CPT was added. On HD 7, simultaneous serum (69.4, 44, and 30.2 mg/L) and CSF (1.7, 2.3, and 2.3 mg/L) concentrations were obtained at 0.25, 1.5, and 4.75 hours from the end of an infusion. Based on these concentrations, CPT CSF penetration ratio ranged from 2.4% to 7.6%. After addition of CPT, the blood and CSF cultures remained negative on a regimen of vancomycin plus CPT. On HD 14, a new left-sided VPL shunt was placed. The patient continued on CPT for a period of 7 days after the new VPL shunt placement. This case demonstrated CPT CSF penetration in a range of 2.4% to 7.6%, approximately half of the rabbit model. This allowed for CSF concentrations at least 50% free time > 4 to 6× MIC of the dosing interval with a dosing regimen of 600 mg IV every 8 hours in a 34.8 kg chronic patient and resulted in a successful clinical outcome with no identified adverse outcomes.

Intraventricular Plus Intravenous Tigecycline for the Treatment of Daptomycin Nonsusceptible Vancomycin-Resistant Enterococci in an Infant with Ventriculoperitoneal Shunt Infection

BACKGROUND

Ventriculoperitoneal (VP) shunt infection, which is 1 of the most important complications of VP shunt is observed at a rate of 4%-17%. Staphylococcus epidermidis is the most common causative agent. Vancomycin-resistant Enterococcus (VRE) is an increasingly common nosocomial pathogen that rarely causes central nervous system infections globally. Current treatment options that have shown appreciable activity against various VRE infections include daptomycin, linezolid, inquinupristin/dalfopristin, and tigecycline. Daptomycin has a particular mode of action and a potent bactericidal activity, making it a useful addition to the clinician's antibiotic collection. Global surveillance data indicate <1.0% rates of daptomycin resistance in enterococci.

CASE DESCRIPTION

Here, we describe, to the best of our knowledge, the first case of successful intraventricular plus intravenous use of tigecycline to treat VP shunt infections caused by daptomycin resistant VRE faecium.

CONCLUSION

Tigecycline is a life-saving option in the treatment of resistant nosocomial infections but it has not yet been approved for use and there are not enough data in terms of dose and side effects associated with its use in children.

Relationship of causative organism and time to infection among children with cerebrospinal fluid shunt infection

OBJECTIVE

Infection is a common complication of cerebrospinal fluid (CSF) shunts, occurring in 6%-20% of children. Although studies are limited, Staphylococcus aureus is thought to cause more rapid and aggressive infection than coagulase-negative Staphylococcus (CONS) or gram-negative organisms. The authors' objective was to evaluate the relationship between the causative organisms of CSF shunt infection and the timing of infection.

METHODS

The authors performed a retrospective cohort study of children who underwent CSF shunt placement at a tertiary care children's hospital over a 9-year period and subsequently developed a CSF shunt infection. The primary predictor variable was the causative organism recovered from CSF culture, characterized as S. aureus, CONS, or gram-negative organisms. The primary outcome was time to infection, defined as the number of days from most recent shunt intervention to the diagnosis of the infection. The association between causative organism and time to infection was visualized using Kaplan-Meier curves, and statistical comparisons were made using nonparametric Kruskal-Wallis tests.

RESULTS

Among 103 children in whom a CSF shunt infection developed, the causative organism was CONS in 57 (55%), S. aureus in 19 (18%), and gram-negative organisms in 9 (9%). The median time to infection did not differ (p = 0.81) for infections caused by CONS (20 days, IQR 11-40), S. aureus (26 days, IQR 12-95), and gram-negative organisms (23 days, IQR 17-34).

CONCLUSIONS

No significant difference in time to infection based on the causative organism was observed among children with a CSF shunt infection.

Intravenous and Intraventricular Daptomycin Plus Intravenous Linezolid Treatment of an Infant with Vancomycin-Resistant Enterococci-Induced Ventriculoperitoneal Shunt Infection

BACKGROUND

The rate of ventriculoperitoneal (VP) shunt infection is reported between 3% and 20%. Vancomycin-resistant enterococci (VRE) are increasingly prevalent nosocomial pathogens worldwide, and they rarely cause infections to the central nervous system. Daptomycin is a cyclic lipopeptide effective antibiotic because of its rapid bactericidal effect. It is a life-saving treatment option for meningitis, bacteremia, sepsis, endocarditis, and urinary system infections caused by VRE.

CASE DESCRIPTION

Here, we present a 2.5-month-old infant boy with a ventriculoperitoneal shunt infection caused by vancomycin-resistant Enterococcus faecium. This is the first report of a pediatric VP shunt infection caused by VRE and treated with a combination of intravenous (IV) linezolid IV and intraventricular (IVT) daptomycin.

CONCLUSION

The patient was admitted to the medical center with umbilical discharge, and shunt revision was applied with the thought of shunt dysfunction. Intermittent umbilical cerebrospinal fluid (CSF) leakage continued, and the patient experienced a fever 2 weeks after the operation. VRE growth in his CSF culture was treated by meropenem and linezolid. Upon continuation of the growth afterwards, the patient was referred to our hospital and underwent extraventricular drainage, and IV linezolid, IV daptomycin (8 mg/kg per day), and IVT daptomycin (2.5 mg/kg per day) was scheduled as treatment. On the fifth day of treatment, there was no growth in the culture, and no side effects were observed during the treatment. A VP shunt was placed in the patient for the 15 days of IV daptomycin plus IVT treatment, and 36 days of linezolid. No infection was observed in the 8-month follow-up period.

Propionibacterium Acnes: Cause of Cerebrospinal Fluid Shunt Infection

Infection after implantation of ventriculo-peritoneal shunts is associated with significant morbidity and mortality. We describe a 9-year-old girl with Propionibacterium acnes shunt infection with negative cerebrospinal fluid cultures, diagnosed by broad-range 16S-rRNA gene polymerase chain reaction. This case supports the use of this molecular diagnostic technique in shunt infections, where the offending pathogens are difficult to culture using traditional methods.

Patient and Treatment Characteristics by Infecting Organism in Cerebrospinal Fluid Shunt Infection

BACKGROUND

Previous studies of cerebrospinal fluid (CSF) shunt infection treatment have been limited in size and unable to compare patient and treatment characteristics by infecting organism. Our objective was to describe variation in patient and treatment characteristics for children with first CSF shunt infection, stratified by infecting organism subgroups outlined in the 2017 Infectious Disease Society of America's (IDSA) guidelines.

METHODS

We studied a prospective cohort of children <18 years of age undergoing treatment for first CSF shunt infection at one of 7 Hydrocephalus Clinical Research Network hospitals from April 2008 to December 2012. Differences between infecting organism subgroups were described using univariate analyses and Fisher's exact tests.

RESULTS

There were 145 children whose infections were diagnosed by CSF culture and addressed by IDSA guidelines, including 47 with Staphylococcus aureus, 52 with coagulase-negative Staphylococcus, 37 with Gram-negative bacilli, and 9 with Propionibacterium acnes. No differences in many patient and treatment characteristics were seen between infecting organism subgroups, including age at initial shunt, gender, race, insurance, indication for shunt, gastrostomy, tracheostomy, ultrasound, and/or endoscope use at all surgeries before infection, or numbers of revisions before infection. A larger proportion of infections were caused by Gram-negative bacilli when antibiotic-impregnated catheters were used at initial shunt placement (12 of 23, 52%) and/or subsequent revisions (11 of 23, 48%) compared with all other infections (9 of 68 [13%] and 13 of 68 [19%], respectively). No differences in reinfection were observed between infecting organism subgroups.

CONCLUSIONS

The organism profile encountered at infection differs when antibiotic-impregnated catheters are used, with a higher proportion of Gram-negative bacilli. This warrants further investigation given increasing adoption of antibiotic-impregnated catheters.

Management of Ventriculoperitoneal Shunt Infections in Adults: Analysis of Risk Factors Associated With Treatment Failure

Background

Little is known regarding the optimal treatment of ventriculoperitoneal (VP) shunt infections in adults. Our aim was to assess the efficacy of treatment strategies and to identify factors that predict failure.

Methods

Retrospective, observational study of patients aged ≥12 years with VP shunt infections (1980 -2014). Therapeutic approaches were classified under 4 headings: only antibiotics (OA), one-stage shunt replacement (OSSR), two-stage shunt replacement (TSSR), and shunt removal without replacement (SR). The primary endpoint was failure of the treatment strategy, defined as the absence of definite cerebrospinal fluid (CSF) sterilization or related mortality. The parameters that predicted failure were analyzed using logistic regression.

Results

Of 108 episodes (51% male, median age 50 years), 86 were analyzed. Intravenous antibiotics were administered for a median of 19 days. Eighty episodes were treated using strategies that combined antibiotic and surgical treatment (37 TSSR, 24 SR, 19 OSSR) and 6 with OA. Failure occurred in 30% of episodes, mostly due to lack of CSF sterilization in OSSR and OA groups. Twelve percent died of related causes and 10% presented superinfection of the CSF temporary drainage/externalized peritoneal catheter. TSSR was the most effective strategy when VP shunt replacement was attempted. The only independent risk factor that predicted failure was retention of the VP shunt, regardless of the strategy.

Conclusions

This is the largest series of VP shunt infections in adults reported to date. VP shunt removal, particularly TSSR when the patient is shunt dependent, remains the optimal choice of treatment and does not increase morbidity.

Pharmacokinetics of continuous-infusion meropenem for the treatment of Serratia marcescens ventriculitis in a pediatric patient

Neither guidelines nor best practices for the treatment of external ventricular drain (EVD) and ventriculoperitoneal shunt infections exist. An antimicrobial regimen with a broad spectrum of activity and adequate cerebrospinal fluid (CSF) penetration is vital in the management of both EVD and ventriculoperitoneal infections. In this case report, we describe the pharmacokinetics of continuous-infusion meropenem for a 2-year-old girl with Serratia marcescens ventriculitis. A right frontal EVD was placed for the management of a posterior fossa mass with hydrocephalus and intraventricular hemorrhage. On hospital day 6, CSF specimens were cultured, which identified a pan-sensitive Serratia marcescens with an initial cefotaxime minimum inhibitory concentration of 1 μg/ml or less. The patient was treated with cefotaxime monotherapy from hospital days 6 to 17, during which her CSF cultures and Gram's stain remained positive. On hospital day 26, Serratia marcescens was noted to be resistant to cefotaxime (minimum inhibitory concentration > 16 μg/ml), and the antimicrobial regimen was ultimately changed to meropenem and amikacin. Meropenem was dosed at 40 mg/kg/dose intravenously every 6 hours, infused over 30 minutes, during which, simultaneous serum and CSF meropenem levels were measured. Meropenem serum and CSF levels were measured at 2 and 4 hours from the end of the infusion with the intent to perform a pharmacokinetic/pharmacodynamic analysis. The resulting serum meropenem levels were 12 μg/ml at 2 hours and "undetectable" at 4 hours, with CSF levels of 1 and 0.5 μg/ml at 2 and 4 hours, respectively. On hospital day 27, the meropenem regimen was changed to a continuous infusion of 200 mg/kg/day, with repeat serum and CSF meropenem levels measured on hospital day 33. The serum and CSF levels were noted to be 13 and 0.5 μg/ml, respectively. The serum level of 13 μg/ml corresponds to an estimated meropenem clearance from the serum of 10.2 ml/kg/minute. Repeat meropenem levels from the serum and CSF on hospital day 37 were 15 and 0.5 μg/ml, respectively. After instituting the continuous-infusion meropenem regimen, only three positive CSF Gram's stains were noted, with the CSF cultures remaining negative. The continuous-infusion dosing regimen allowed for 100% probability of target attainment in the serum and CSF and a successful clinical outcome.