Carbapenem-resistant Acinetobacter baumannii: an emerging threat for patients with post-neurosurgical meningitis

Evaluation of Intraventricular/Intrathecal Antimicrobial Therapy in the Treatment of Nosocomial Meningitis Caused by Multidrug-Resistant Gram-Negative Bacteria after Central Nervous System Surgery

Introduction

Postoperative meningitis (POM) is an infection with high mortality and morbidity following central nervous system surgery due to trauma or tumor. Intrathecal/intraventricular (IT/IVT) antibiotic administrations have been considered as the last treatment options for multidrug-resistance (MDR) Gram-negative bacteria that do not respond to intravenous (IV) regimens. IT/IVT can bypass the blood-brain barrier, obtain a more effective antibiotic concentration in CSF, and reduce systemic side effects. We aimed to determine the characteristics of postoperative patients who were diagnosed with MDR POM during follow-up in our intensive care unit (ICU). Material and Methods. In this study, POM patients who were followed up in ICU after the central nervous system intervention between January 2016 and December 2019 and whose MDR Gram-negative bacteria were isolated from CSF were evaluated. As soon as the patients were diagnosed with POM, a catheter was inserted and treatment was started.

Results

Microbiological eradication was achieved in 3 ± 0.8 days with 30 mg/day amikacin treatment in POM due to K. pneumoniae and 3.7 ± 1.95 days with colistin sodium 10 mg/day treatment in POM due to A. baumannii via IT/IVT catheter. IT/IVT treatment was utilized for a median of 10 days and continued until the defined cure criteria were achieved. While cure was achieved in 6 of 14 POM cases, 8 of them were exitus. Discussion and Conclusion. To avoid the severe consequences of postoperative meningitis, acting fast and adding IT/IVT methods to parenteral administration routes by considering the distribution of MDR microorganisms within the hospital while planning effective treatment will increase the clinical success.

Clinical Features of Post-Operative Nosocomial Meningitis in Adults and Evaluation of Efficiency of Intrathecal Treatment

Background: Post-operative nosocomial meningitis is a critical complication that develops in patients after neurosurgical interventions and operations. Patients and Methods: Data were collected for 65 patients who were diagnosed as having nosocomial meningitis after neurosurgery. The agent profile, clinical and biochemical differences in gram-negative and gram-positive meningitis, and the effectiveness of intrathecal antibiotic administration in cases with carbapenem-resistant gram-negative agents were evaluated. Results: Gram-negative bacteria were isolated in 52.3% of patients. In gram-negative cases of post-operative nosocomial meningitis, white blood cell count (p = 0.015), C-reactive protein (p = 0.001), cerebrospinal fluid leukocyte count (p = 0.0001), and protein (p = 0.0001) were higher, and glucose (p = 0.002) was lower. Concurrent bacteremia (p = 0.041), 14-day mortality (p = 0.022), and 30-day mortality (p = 0.023) were higher in gram-negative cases. Empirical treatment was appropriate in 78.5% of the patients. Seventeen patients (26.2%) received intrathecal antibiotic agents in addition to intravenous antibiotic treatment because of carbapenem-resistant gram-negative bacteria. Nine (53%) of the patients receiving intrathecal therapy had Acinetobacter baumannii as the agent, six had Klebsiella pneumoniae (35.4%), one had Pseudomonas aeruginosa (5.8%), and one had Providencia rettgeri (5.8%). The mean intravenous treatment duration was 21.4 ± 10.6 (4-60) days, and the mean intrathecal treatment duration was 17.6 ± 14.0 (1-51) days. Eleven patients received colistimethate sodium intrathecally (1 × 10 mg/d), three patients received amikacin intrathecally (1 × 10 mg/d), and three patients received gentamicin intrathecally (1 × 10 mg/d). Clinical and microbiologic treatment success was achieved in nine patients (53%). Conclusions: In cases of meningitis caused by carbapenem-resistant agents, intrathecal administration of antibiotic agents such as gentamicin, amikacin, and colistin with limited blood-brain barrier transition in intravenous administration will increase survival. Therefore, intrathecal antibiotic administration should be considered as a part of routine of nosocomial meningitis.

[Off label uses of tigecycline]

INTRODUCTION

Tigecycline is a relatively new antibiotic that have very limited valid indications. When no other alternative is available, this drug is widely used off label with promising results. The objective of this study is to summarize the different off label uses of tigecycline so that we can decide when and how to prescribe it in the absence of guidelines.

MATERIAL AND METHODS

This study a revue of the literature collecting all the articles concerning the off label uses of tigecycline.

RESULTS

Tigecycline was widely prescribed, off label, to treat infections with controversial results. Randomised clinical trials were conducted to evaluate its use to treat pneumonia. The results for this indication have a respectable level of evidence. For the other indications, the data collected was insufficient to support tigecycline prescription. In fact, different protocols were used which makes it hard to evaluate the efficacy and to conclude to the best treatment regimen. A tendency to prescribe high doses of the molecule was noted in different studies. When prescribed off label, tigecycline prescriptions were associated with a higher mortality and incidence of side effects.

CONCLUSION

The tigecycline remains a valid option for the treatment of infections dues to multi-resistant bacteria especially when other alternatives are scarce or in cases of renal failure.

Trends of Intra-Cranial Bacterial Infection in Patients Requiring Emergency Neurosurgery

Background: Intra-cranial bacterial infection is a serious complication in emergency neurosurgical patients, and few data are available on the trends of these infections and the rates of antibacterial drug resistance. Methods: We surveyed retrospectively the patients with intra-cranial bacterial infection in our emergency neurosurgical center between January 2009 and December 2018. Demographic characteristics, causative bacteria, and antimicrobial susceptibility test results were collected. Results: A total of 100 patients with intra-cranial bacterial infection, 1.41% of our patients, were enrolled. There were 123 strains of bacteria cultured from the cerebrospinal fluid (CSF), consisting of 96 strains of gram-negative (GN) bacteria and 27 strains of gram-positive (GP) bacteria. Compared with the GP bacteria, the percentage of GN bacteria increased to 75.0% of the total near the end of the study. Compared with Acinetobacter baumannii, Klebsiella pneumoniae also showed an uptrend. Most of the bacteria were multi-drug-resistant (MDR). We further analyzed the consistency of CSF and sputum cultures from the same patient. The ratio of Klebsiella pneumoniae and Acinetobacter baumannii to the corresponding strains in the CSF were 77.0% and 62.0%. Conclusions: The bacteria recovered from the CSF were mainly GN. The tendency of GN bacteria showed an uptrend, especially for Klebsiella pneumoniae. Furthermore, most of the bacteria were MDR.

Neurodevelopment Outcome of Neonates Treated With Intraventricular Colistin for Ventriculitis Caused by Multiple Drug-Resistant Pathogens-A Case Series

Background: Multiple-drug-resistant Gram-negative bacteria (MDR-GNB)-associated neonatal ventriculitis is a life-threatening complication that needs timely diagnosis and effective treatment with broad-spectrum antimicrobials in critical-care settings. Inadequate penetration of antibiotics through the blood-brain barrier also demands an intraventricular (IVT) route of administration. This study reports mortality and neurodevelopmental sequelae of neonates till 18 months of age, who received IVT-colistin for treating MDR-GNB associated ventriculitis. Methods: In a case series of seven neonates with ventriculitis due to MDR-GNB at NICU of Aga Khan University Hospital, Pakistan, between June 2015 and 2018, we reviewed IVT-colistin therapy in critically ill neonates. Treatment outcomes were assessed based on clinical sign's resolution and MDR-GNB eradication in subsequent CSF cultures. Neurodevelopmental outcomes were evaluated at 18 months after discharge. Results: The average birth weight was 1.38 kg (range: 1.02-1.5 kg), and the average gestational age was 30.7 weeks (ranged: 26-34 weeks). All neonates reported colistin-sensitive MDR-GNB in CSF, five with Acinetobacter baumannii, and polymicrobial CNS infection was found in two patients (one due to Klebsiella pneumonia and A. baumannii and one due to K. pneumonia and Escherichia coli). All neonates received IVT colistin and concomitant intravenous meropenem, and five of them also received intravenous colistin. One neonate died. At the 18-month assessment, only one neonate had cerebral palsy and hydrocephaly and 50% had seizure disorders. Conclusion: Practicing intraventricular antibiotics in the neonatal population is challenging but may be used successfully, especially to overcome the limitation of poor penetration through the blood-brain barrier.

Outcome Following the Treatment of Ventriculitis Caused by Multi/Extensive Drug Resistance Gram Negative Bacilli; Acinetobacter baumannii and Klebsiella pneumonia

Introduction: CNS ventriculitis is a serious complication following an intracranial insult that demands immediate treatment with broad-spectrum antibiotics in a critical care setting. Infections due to multi/extensive drug resistance (MDR/XDR) microorganisms are very challenging, which may demand an additional approach to the ongoing practice; intravenous and intraventricular administration of antibiotics.

Aim: To study the efficacy and safety of thorough ventricular irrigation followed by daily intraventricular antibiotic administration in patients with MDR/XDR ventriculitis.

Materials and Methods: A retrospective analysis was done on 19 inpatients with ventriculitis caused by Acinetobacter baumannii (AB) or Klebsiella pneumonia (KP), at Shanghai Tenth People's Hospital from January 2016 to October 2017. We reviewed our experience; the role of thorough ventricular irrigation with Colistin mixed normal saline, followed by intraventricular Colistin therapy. Treatment outcomes were evaluated based on the clinical symptoms, Cerebro-Spinal Fluid (CSF) culture, laboratory findings and complications.

Results: A total of 19 patients were included (15 males and 4 females), with a mean age in years of 51, which ranged from 18–67. Fourteen patients had Acinetobacter baumannii (AB) and 5 had Klebsiella pneumoniae (KP). The average CSF sterilization period following ventricular irrigation and intraventricular Colistin was 6 days. Sixteen patients (84%) were cured, and 3 patients (15%) died during the course of the treatment.

Conclusion: In addition to Intraventricular Colistin, thorough ventricular irrigation could increase the cure rate up to 84% in patients suffering from MDR/XDR CNS ventriculitis.

Acinetobacter baumannii meningitis in children: a case series and literature review

INTRODUCTION

The incidence of Acinetobacter baumannii meningitis, which typically occurs after neurosurgery, has increased in recent years. Pediatric Acinetobacter baumannii meningitis due to the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains has important clinical significance.

METHODOLOGY

We retrospectively reviewed the clinical course and outcome of nine cases of meningitis due to Acinetobacter baumannii in children and reviewed the relevant literature.

RESULTS

Seven patients had a history of neurosurgery, and the average time from the first surgery to cerebrospinal fluid (CSF) culture in these seven patients was 23.71 ± 17.43 days. Of all nine patients, four patients showed MDR isolates, two showed XDR isolates, and one showed pan-drug-resistant (PDR) isolates. Three patients received an intrathecal injection of amikacin. Two patients received intravenous colistin (5 mg/kg), and one received polymyxin B (2 mg/kg). The mean hospitalization duration was 39.44 days. Four patients eventually died: two with MDR Acinetobacter, one with PDR Acinetobacter, and one with susceptible Acinetobacter. Two of them still had positive CSF cultures at death.

CONCLUSION

Acinetobacter baumannii meningitis is usually associated with neurosurgery and the placement of foreign material, and it usually has a high mortality. Intrathecal or intraventricular polymyxin administration is expected to be an effective choice for meningitis but requires further study.

Outcomes of post-neurosurgical ventriculostomy-associated infections

Background:

Ventriculostomy-associated infection (VAI) is a major concern to physicians. Limited studies have looked at the outcomes of external ventricular drain (EVD) infection and predictors of unfavorable outcomes. In this study, we assessed the outcomes of EVD infection and predictors of unfavorable outcomes.

Methods:

This was a retrospective medical chart review, conducted at the Aga Khan University Hospital. All the patients irrespective of age and gender, fulfilling the diagnostic criteria of VAI were included. Patients with preexisting bacterial meningitis or ventriculitis were excluded from the study. Outcome assessment was based on Glasgow outcome scale (GOS) at 1 and 3 months after procedure. Other outcomes included 30-day mortality and total length of hospital stay.

Results:

We included 256 patients in the study. 66 patients (25.8%) developed VAI. EVD was the primary procedure in 21 (31.8%) cases. Most patients, 24 (36.4%), had EVD as a secondary procedure for tumor surgery. Median interval between EVD placement and diagnosis of infection was 3 days. Mean length of stay in VAI patients was 31.85 ± 20.53 days. Seven patients required ICU care. Ten patients (15.2%) expired during hospital stay or within 30 days of discharge and further four had GOS of 2 or 3. A total of 52 patients had a favorable outcome after 6 months.

Conclusions:

Rate of VAI in this cohort was high. VAI is associated with increased morbidity, mortality, and prolonged hospital stay.

Multidrug-resistant Acinetobacter meningitis in children

Acinetobacter species have emerged as one of the most troublesome pathogens for healthcare institutions globally. In more recent times, nosocomial infections involving the central nervous system, skin and soft tissue, and bone have emerged as highly problematic. Acinetobacter species infection is common in intensive care units; however, Acinetobacter baumannii meningitis is rarely reported. Here, we report two cases of Acinetobacter baumannii meningitis which was multidrug resistance and ultimately required the carbapenem group of drugs for the treatment.

Risk factors associated with postcraniotomy meningitis: A retrospective study

Postcraniotomy meningitis (PCM) is a major challenge in neurosurgery, and changing patterns of infectious agents in PCM have been noted. The limited epidemiological data and urgent clinical needs motivated this research. We conducted this study to determine a risk assessment for PCM and the current pattern of infectious agents.We performed a retrospective case-control study of significant cases of postcraniotomy meningitis in the Changhua Christian Hospital System between January 1, 2008, and December 31, 2012. Postcraniotomy meningitis was diagnosed in 22 out of 4392 surgical patients; this data was reviewed for risk assessment.This study assessed the risk factors for postcraniotomy meningitis and found that it was more frequently seen in patients who were elderly (OR = 1.57, 95% CI = 1.32-2.98, P = 0.013), underwent emergency procedures (OR = 4.82, 95% CI = 1.50-14.53, P = 0.008), had leak of cerebrospinal fluid (OR = 4.62, 95% CI = 2.03-10.50, P = 0.012), had external ventricular drainage (OR = 4.68, 95% CI = 2.46-8.87, P = 0.006), were admitted to the intensive care unit (OR = 2.41, 95% CI = 1.53-8.08, P = 0.012), had used drain placement >72 hours (OR = 2.66, 95% CI = 1.04-4.29, P = 0.007), had surgery >4.5 hours (OR = 2.38, 95% CI = 1.39-4.05, P = 0.005), had repeat operations (OR = 2.74, 95% CI = 1.31-5.73, P = 0.018), endured trauma (OR = 5.97, 95% CI = 1.57-17.61, P = 0.007), or had 30-days mortality (OR = 5.07, 95% CI = 2.20-11.48, P = 0.001). The predominant pathogens isolated from cerebrospinal fluid were Staphylococcus aureus in 8 patients (36.7%) and Acinetobacter baumannii in 7 patients (31.8%). In our study, the mortality rate was 5.1% among all postcraniotomy patients.Accurate risk assessment, early diagnosis, and choice of appropriate antibiotics in accordance with epidemiologic information are the cornerstones of reducing mortality and morbidity in PCM. The changing pattern of infectious agents in PCM over time suggests the necessity of further studies to provide the most up-to-date insight to physicians.

The Role of Endoscopic Lavage in Recalcitrant Multidrug-Resistant Gram-Negative Ventriculitis Among Neurosurgical Patients

INTRODUCTION

Ventriculitis is a serious infection associated with high mortality even when both intravenous (IV) and intrathecal (IT) antibiotics are administered. Poor outcome in patients with ventriculitis indicates the need to be more aggressive in our attempts to expeditiously eradicate the infection. The purpose of this study was to evaluate the role of endoscopic lavage (EL) in patients with severe purulent ventriculitis, unresponsive to IV and IT antibiotics.

METHODS

All consecutive patients with severe ventriculitis caused by multidrug-resistant gram-negative bacteria, undergoing EL after failure of prolonged courses of IV and IT antibiotics, were included in the study. The outcome in all these patients was otherwise expected to be uniformly dismal.

RESULTS

There were 5 males and 2 females. The age range was one month to 45 years. All patients had frank intraventricular pus. Acinetobacter baumannii was the most common organism grown in cultures. Two patients had multiple bacterial growth in cerebrospinal fluid cultures. The duration of pre-EL IV/IT antibiotics ranged from 3 to 8 weeks. Microbiological cure was achieved in all (7/7) and clinical cure in 86% of patients (6/7). One patient died despite achieving cerebrospinal fluid sterilization 3 months later as a result of progressive white matter edema.

CONCLUSIONS

The addition of IT antibiotics has resulted in improved outcome in patients with ventriculitis; however, some patients continue to be unresponsive to antibiotics. EL can play a complementary role in eradicating such recalcitrant infections. EL should be considered in any patient with ventriculitis, if infection persists even after ∼7-10 days of IVand IT antibiotics.

Empirical Combination Antibiotic Therapy Improves the Outcome of Nosocomial Meningitis or Ventriculitis in Neuro-Critical Care Unit Patients

BACKGROUND

Nosocomial meningitis and ventriculitis (MEN) are serious complications in neuro-critical care unit (NCCU) patients. Few data are available on the risk factors and mortality rates among NCCU patients with these disorders caused by multi-drug-resistant (MDR) pathogens. Our aim was to identify the risk factors for MEN caused by such pathogens and in-hospital deaths in critically ill neurologic patients and to evaluate the impact of empirical combination antibiotic therapy (ECAT) on the outcomes of these patients.

METHODS

We conducted a retrospective study of critically ill neurologic patients having nosocomial MEN who were admitted to the NCCU in a university teaching hospital from January 2003 to December 2013, with MEN being defined using the modified U.S. Centers for Disease Control and Prevention criteria for nosocomial infections.

RESULTS

In total, 6,149 consecutive NCCU patients were screened; 132 had MEN. Logistic regression analysis demonstrated that MDR MEN was related to infection with gram-negative (GN) bacteria (odds ratio 3.16; 95% confidence interval [CI] 1.08-9.25; p = 0.036), and inadequate initial antibiotic therapy (odds ratio 9.80; 95% CI 3.79-25.32; p < 0.001). The ECAT was associated with a lower mortality rate (hazard ratio 0.35; 95% CI 0.14-0.86; p = 0.022) in Cox proportional hazard regression analysis. The other variable independently associated with a greater mortality rate was a greater Simplified Acute Physiology Score II (hazard ratio 1.07; 95% CI 1.01-1.13; p = 0.018).

CONCLUSIONS

Initial combination therapy improves the in-hospital mortality rate among NCCU patients with nosocomial MEN. Inadequate initial antibiotic therapy and GN infection were associated with MDR MEN.

Infections in patients undergoing craniotomy: risk factors associated with post-craniotomy meningitis

OBJECT The authors performed a prospective study to define the prevalence and microbiological characteristics of infections in patients undergoing craniotomy and to clarify the risk factors for post-craniotomy meningitis. METHODS Patients older than 18 years who underwent nonstereotactic craniotomies between January 2006 and December 2008 were included. Demographic, clinical, laboratory, and microbiological data were systemically recorded. Patient characteristics, craniotomy type, and pre- and postoperative variables were evaluated as risk factors for meningitis RESULTS Three hundred thirty-four procedures were analyzed (65.6% involving male patients). Traumatic brain injury was the most common reason for craniotomy. Almost 40% of the patients developed at least 1 infection. Ventilator-associated pneumonia (VAP) was the most common infection recorded (22.5%) and Acinetobacter spp. were isolated in 44% of the cases. Meningitis was encountered in 16 procedures (4.8%), and CSF cultures were positive for microbial growth in 100% of these cases. Gram-negative pathogens (Acinetobacter spp., Klebsiella spp., Pseudomonas aeruginosa, Enterobacter cloaceae, Proteus mirabilis) represented 88% of the pathogens. Acinetobacter and Klebsiella spp. demonstrated a high percentage of resistance in several antibiotic classes. In multivariate analysis, the risk for meningitis was independently associated with perioperative steroid use (OR 11.55, p = 0.005), CSF leak (OR 48.03, p < 0.001), and ventricular drainage (OR 70.52, p < 0.001). CONCLUSIONS Device-related postoperative communication between the CSF and the environment, CSF leak, and perioperative steroid use were defined as risk factors for meningitis in this study. Ventilator-associated pneumonia was the most common infection overall. The offending pathogens presented a high level of resistance to several antibiotics.

Non-cephalosporin-susceptible, glucose non-fermentative Gram-negative bacilli meningitis in post-neurosurgical adults: clinical characteristics and therapeutic outcome

OBJECTIVE

The clinical and laboratory characteristics of non-cephalosporin-susceptible (non-CS) glucose non-fermentative Gram-negative (G(-)) infections in adults with postneurosurgical meningitis are rarely examined solely in the literature.

METHODS

The data of 28 post-neurosurgical adults meningitis with glucose non-fermentative G(-) infections, collected during a study period of 5 years (2006-2010), were reviewed. The clinical and laboratory data between the non-cephalosporin-susceptible groups and the cephalosporin-susceptible groups were compared.

RESULTS

A total of 30 G(-) strains were collected from the 28 enrolled cases. Among the implicated glucose non-fermentative G(-) strains, 18 strains, belonging to 17 cases, were non-CS. Among the 18 non-cephalosporin-susceptible strains, Acinetobacter spp. (39%, 7/18) was the most common, followed by Pseudomonas spp. (22%, 4/18), Stenotrophomonas maltophilia (22%, 4/18) and Elizabethkingia meningoseptica (11%, 2/18). With a comparative analysis, there were no significant difference between the non-cephalosporin-susceptible and cephalosporin-susceptible glucose non-fermentative G(-) groups. The clinical and laboratory data were also of no statistical significance between the fatal (n=4) and non-fatal (n=13) non-cephalosporin-susceptible groups.

CONCLUSION

Sixty percent (18/30) of implicated glucose non-fermentative G(-) strains of post-NS meningitis in adults are non-cephalosporin-susceptible. Among the non-cephalosporin-susceptible glucose non-fermentative G(-) strains, Acinetobacter spp., Pseudomonas spp., S. maltophilia and E. meningoseptica are the commonly implicated pathogens, and their emergence in this specific group of meningitis has caused a therapeutic dilemma. The clinical manifestations of non-cephalosporin-susceptible glucose non-fermentative G(-) meningitis were not unique; therefore, only bacterial culture and antimicrobial susceptibility test are the methods for identification confirmation.

Intraventricular and intrathecal colistin as the last therapeutic resort for the treatment of multidrug-resistant and extensively drug-resistant Acinetobacter baumannii ventriculitis and meningitis: a literature review

Acinetobacter baumannii ventriculitis/meningitis due to the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains has become a clinical entity of considerable importance in recent years. A review of the available literature regarding intraventricular (IVT) or intrathecal (ITH) administration of colistin in MDR and XDR A. baumannii ventriculitis/meningitis was conducted and a total of 83 episodes in 81 patients were identified (71 cases in adults and 10 in children and neonates). Colistin was administered via the IVT and ITH route in 52 and 22 cases, respectively, whilst in 7 cases the exact route was not identified. The median dose of local colistin was 125000 IU (10mg) with a range of 20000 IU (1.6 mg) to 500000 IU (40 mg) in adults, whilst a dose of 2000 IU/kg (0.16 mg/kg) up to 125000 IU (10mg) was used in the paediatric population. The median duration of treatment of IVT/ITH polymyxin E was 18.5 days, whilst the median time to achieve sterilisation of cerebrospinal fluid was 4 days. The rate of successful outcome was 89%, and toxicity related to treatment mainly manifested as reversible chemical ventriculitis/meningitis was reported in nine cases (11%). Nowadays, IVT and ITH colistin represents the last resort treatment of MDR and XDR A. baumannii ventriculitis/meningitis, offering a unique, rather safe and successful mode of therapy.

Prolonged triple therapy for persistent multidrug-resistant Acinetobacter baumannii ventriculitis

PURPOSE

A case of persistent multidrug-resistant (MDR) Acinetobacter baumannii ventriculitis successfully treated with a prolonged and novel combination of antimicrobials is reported.

SUMMARY

A 38-year-old, 84-kg Caucasian woman with a recent history of craniotomy was admitted with nausea, fever, headache, photophobia, and drainage from her craniotomy incision. She underwent a repeat craniotomy on hospital day 4 with abscess debridement and repair of a cerebrospinal fluid leak. Cultures grew MDR A. baumannii, coagulase-negative Staphylococcus species, and methicillin-resistant Staphylococcus aureus. Based on the limited published pharmacokinetic and pharmacodynamic data for colistin, we determined a favorable outcome with i.v. colistin monotherapy was unlikely and decided to treat the patient with simultaneous i.v. and intraventricular colistin, as well as intraventricular tobramycin and i.v. rifampin. She was treated with a total of 36 days of intraventricular colistin, 40 days of intraventricular tobramycin, 51 days of i.v. colistin and rifampin, and 56 days i.v. vancomycin for infection that persisted despite multiple debridements. The patient had subsequent improvement in clinical manifestations and eradication of infection. She was subsequently discharged to an acute rehabilitation facility on hospital day 77 with posttreatment sequelae including mental impairment and renal failure requiring hemodialysis. Follow-up visits revealed significant improvement in her mental status, speech, and strength on the side not affected by the stroke.

CONCLUSION

Prolonged combination therapy with intraventricular colistin and tobramycin plus i.v. colistin, rifampin, and vancomycin led to the resolution of a persistent central nervous system infection caused by MDR A. baumannii.

Changing pattern of antibiotic susceptibility in intensive care units: ten years experience of a university hospital

The study was performed to assess microorganisms and antibiotic susceptibility patterns during ten years in intensive care units of a University Hospital. Infection Control Committee has active, prospective surveillance in ICUs for thirteen years. Ten years data of ICUs was evaluated retrospectively from surveillance forms. Microorganisms and their antibiotic resistance were recorded according to the years. During ten years, gram negative microorganisms were the most frequent isolated microorganisms from clinical specimens. Acinetobacter baumannii (21.8%), Pseudomonas aerigunosa (16%), Escherichia coli (10.4%) and Klebsiella pneumoniae (8%) were the most common gram negative microorganisms. However, Staphylococcus aureus was the most prevalent gram positive microorganism, the incidence decreased from 18.6% to 4.8% during ten years. Also antibiotic susceptibility of microorganisms changed during ten years. Carbapenem resistance increased from 44% to 92% in A. baumannii and ciprofloxacin resistance increased in E. coli from 28% to 60% and in K. pneumoniae from 21% to 55% during ten years. However, methicilin resistance decreased in S. aureus from 96% to 54%. In conclusion, antibiotic resistance is growing problem in ICUs. Rationale antibiotic policies and infection control measures will prevent the development of resistance.

Post-neurosurgical multidrug-resistant Acinetobacter baumannii meningitis successfully treated with intrathecal colistin. A new case and a systematic review of the literature

INTRODUCTION

Post-neurosurgical nosocomial meningitis has become an important subgroup of bacterial meningitis in the hospital setting. The increase in meningitis caused by multidrug-resistant (MDR) Acinetobacter baumannii has resulted in a significant reduction in available treatment options.

CASE REPORT AND LITERATURE REVIEW

We report the case of a 36-year-old man with a complex craniofacial trauma, who developed a nosocomial meningitis due to MDR A. baumannii that was cured by intrathecal colistin. The case is contextualized among all the published cases of Acinetobacter meningitis treated with topical colistin found through a MEDLINE search of the literature. To date, including the present case, eight reported cases of Acinetobacter meningitis have been treated with colistin administered by an intrathecal route and 24 by an intraventricular route. The daily dose of colistin used ranged from 1.6 mg every 24 h to 20 mg every 24 h in adult patients. The median time necessary to obtain cerebrospinal fluid sterilization was 4.1 days, and treatment was always successful even if in two cases Acinetobacter meningitis relapsed. Toxicity probably or possibly related to the topical administration of colistin was noted in five out of the 32 patients.

CONCLUSIONS

Topical colistin can be an effective and safe treatment for MDR Acinetobacter meningitis.

Brain abscess caused by multidrug-resistant Acinetobacter baumannii

This 24-year-old soldier had a history of polytrauma caused by firearm missiles of a fragmentation weapon. He was referred to the Hospital Militar Central, where multiple shrapnel wounds in the head, face, thorax, and extremities were found. A brain abscess was documented and drained, and a culture grew a multidrug-resistant Acinetobacter baumannii. An appropriate antibiotic treatment was started but did not lead to a good response, and the patient died. The clinical course of the illness is presented, as is its treatment and the role of A baumannii as an etiological agent of a brain abscess. To the authors' knowledge, there have been no reported cases in the worldwide literature of brain abscess by this infectious agent.

Management of meningitis due to antibiotic-resistant Acinetobacter species

Acinetobacter meningitis is becoming an increasingly common clinical entity, especially in the postneurosurgical setting, with mortality from this infection exceeding 15%. Infectious Diseases Society of America guidelines for therapy of postneurosurgical meningitis recommend either ceftazidime or cefepime as empirical coverage against Gram-negative pathogens. However, assessment of the pharmacodynamics of these cephalosporins in cerebrospinal fluid suggests that recommended doses will achieve pharmacodynamic targets against fewer than 10% of contemporary acinetobacter isolates. Thus, these antibiotics are poor options for suspected acinetobacter meningitis. From in vitro and pharmacodynamic perspectives, intravenous meropenem plus intraventricular administration of an aminoglycoside may represent a superior, albeit imperfect, regimen for suspected acinetobacter meningitis. For cases of meningitis due to carbapenem-resistant acinetobacter, use of tigecycline is not recommended on pharmacodynamic grounds. The greatest clinical experience rests with use of polymyxins, although an intravenous polymyxin alone is inadvisable. Combination with an intraventricularly administered antibiotic plus removal of infected neurosurgical hardware appears the therapeutic strategy most likely to succeed in this situation. Unfortunately, limited development of new antibiotics plus the growing threat of multidrug-resistant acinetobacter is likely to increase the problems posed by acinetobacter meningitis in the future.

Clinical review: balancing the therapeutic, safety, and economic issues underlying effective antipseudomonal carbapenem use

Antipseudomonal carbapenems have played a useful role in our antimicrobial armamentarium for 20 years. However, a review of their use during that period creates concern that their clinical effectiveness is critically dependent on attainment of an appropriate dosing range. Unfortunately, adequate carbapenem dosing is missed for many reasons, including benefit/risk misconceptions, a narrow therapeutic window for imipenem and meropenem (due to an increased rate of seizures at higher doses), increasingly resistant pathogens requiring higher doses than are typically given, and cost containment issues that may limit their use. To improve the use of carbapenems, several initiatives should be considered: increase awareness about appropriate treatment with carbapenems across hospital departments; determine optimal dosing regimens for settings where multidrug resistant organisms are more likely encountered; use of, or combination with, an alternative antimicrobial agent having more favorable pharmacokinetic, pharmacodynamic, or adverse event profile; and administer a newer carbapenem with lower propensity for resistance development (for example, reduced expression of efflux pumps or greater stability against carbapenemases).

Acinetobacter baumannii: emergence of a successful pathogen

Acinetobacter baumannii has emerged as a highly troublesome pathogen for many institutions globally. As a consequence of its immense ability to acquire or upregulate antibiotic drug resistance determinants, it has justifiably been propelled to the forefront of scientific attention. Apart from its predilection for the seriously ill within intensive care units, A. baumannii has more recently caused a range of infectious syndromes in military personnel injured in the Iraq and Afghanistan conflicts. This review details the significant advances that have been made in our understanding of this remarkable organism over the last 10 years, including current taxonomy and species identification, issues with susceptibility testing, mechanisms of antibiotic resistance, global epidemiology, clinical impact of infection, host-pathogen interactions, and infection control and therapeutic considerations.