[Influenza-associated acute necrotizing encephalitis: unknown makes undertreated?] / Influenza-geassocieerde acute necrotiserende encefalitis.

BACKGROUND: Influenza-associated acute necrotizing encephalitis (ANE) is a very rare, but severe complication from influenza infection. CASE DESCRIPTION: We present a 48 year old male who presented with fever, malaise, confusion and altered mental status (E4M5V2) and influenza A infection. He quickly develops convulsions after which he is intubated and admitted to the Intensive Care Unit following which he remains comatose (E1M1V1). The diagnosis of influenza associated acute necrotizing encephalitis is made based on his neurological symptoms, generalized slowing on electro-encephalogram, classic bilateral findings on MRI in the thalamus and basal ganglia and proven influenza infection in the cerebrospinal fluid. CONCLUSION: Acute necrotising encephalitis is a severe complication from a common infection. It is advised to consider early MRI imaging in patients with influenza and fitting neurological symptoms and to consider treatment with corticosteroids.

Corrigendum: Comprehensive Molecular Characterization of Escherichia coli Isolates from Urine Samples of Hospitalized Patients in Rio de Janeiro, Brazil.

[This corrects the article DOI: 10.3389/fmicb.2018.00243.].

Characterization of fosfomycin heteroresistance among multidrug-resistant Escherichia coli isolates from hospitalized patients in Rio de Janeiro, Brazil.

OBJECTIVES: Urinary tract infections (UTIs) caused by multidrug-resistant Escherichia coli have become a major medical concern. Old antibiotics such as fosfomycin have become an alternative therapeutic option due to their effectiveness and, as a result, fosfomycin is now used as a first-line drug for the treatment of UTIs in many countries. Despite low resistance rates, fosfomycin heteroresistance, defined as a phenomenon where subpopulations of bacteria are resistant to high antibiotic concentrations whereas most of the bacteria are susceptible, is an underestimated problem. METHODS: The frequency of heteroresistance in E. coli isolated from hospitalized patients in Brazil and its effect on susceptibility of E. coli in biofilms was studied and the isolates were molecularly characterized to reveal the mechanisms behind their fosfomycin heteroresistance using whole-genome sequencing. RESULTS: A higher frequency of fosfomycin heteroresistance compared with other studies was found. In biofilms, most heteroresistant isolates were less sensitive to fosfomycin than control isolates and showed overexpression of metabolic genes thereby increasing their survival rate. Molecular characterization showed that some resistant subpopulations derived from heteroresistant isolates had a defect in their fosfomycin uptake system caused by mutations in transporter and regulatory genes, whereas others overexpressed the murA gene. None to minor effects on bacterial fitness were observed. Oxidative stress protection, virulence and metabolic genes were differentially expressed in resistant subpopulations and heteroresistant isolates. CONCLUSION: Frequent detection of heteroresistance in UTIs may play a role in the failure of antibiotic treatments and should therefore be more carefully diagnosed.

Determining the Virulence Properties of Escherichia coli ST131 Containing Bacteriocin-Encoding Plasmids Using Short- and Long-Read Sequencing and Comparing Them with Those of Other E. coli Lineages.

Escherichia coli ST131 is a clinical challenge due to its multidrug resistant profile and successful global spread. They are often associated with complicated infections, particularly urinary tract infections (UTIs). Bacteriocins play an important role to outcompete other microorganisms present in the human gut. Here, we characterized bacteriocin-encoding plasmids found in ST131 isolates of patients suffering from a UTI using both short- and long-read sequencing. Colicins Ia, Ib and E1, and microcin V, were identified among plasmids that also contained resistance and virulence genes. To investigate if the potential transmission range of the colicin E1 plasmid is influenced by the presence of a resistance gene, we constructed a strain containing a plasmid which had both the colicin E1 and blaCMY-2 genes. No difference in transmission range was found between transformant and wild-type strains. However, a statistically significantly difference was found in adhesion and invasion ability. Bacteriocin-producing isolates from both ST131 and non-ST131 lineages were able to inhibit the growth of other E. coli isolates, including other ST131. In summary, plasmids harboring bacteriocins give additional advantages for highly virulent and resistant ST131 isolates, improving the ability of these isolates to compete with other microbiota for a niche and thereby increasing the risk of infection.

Comprehensive Molecular Characterization of Escherichia coli Isolates from Urine Samples of Hospitalized Patients in Rio de Janeiro, Brazil.

Urinary tract infections (UTIs) are often caused by Escherichia coli. Their increasing resistance to broad-spectrum antibiotics challenges the treatment of UTIs. Whereas, E. coli ST131 is often multidrug resistant (MDR), ST69 remains susceptible to antibiotics such as cephalosporins. Both STs are commonly linked to community and nosocomial infections. E. coli phylogenetic groups B2 and D are associated with virulence and resistance profiles making them more pathogenic. Little is known about the population structure of E. coli isolates obtained from urine samples of hospitalized patients in Brazil. Therefore, we characterized E. coli isolated from urine samples of patients hospitalized at the university and three private hospitals in Rio de Janeiro, using whole genome sequencing. A high prevalence of E. coli ST131 and ST69 was found, but other lineages, namely ST73, ST648, ST405, and ST10 were also detected. Interestingly, isolates could be divided into two groups based on their antibiotic susceptibility. Isolates belonging to ST131, ST648, and ST405 showed a high resistance rate to all antibiotic classes tested, whereas isolates belonging to ST10, ST73, ST69 were in general susceptible to the antibiotics tested. Additionally, most ST69 isolates, normally resistant to aminoglycosides, were susceptible to this antibiotic in our population. The majority of ST131 isolates were ESBL-producing and belonged to serotype O25:H4 and the H30-R subclone. Previous studies showed that this subclone is often associated with more complicated UTIs, most likely due to their high resistance rate to different antibiotic classes. Sequenced isolates could be classified into five phylogenetic groups of which B2, D, and F showed higher resistance rates than groups A and B1. No significant difference for the predicted virulence genes scores was found for isolates belonging to ST131, ST648, ST405, and ST69. In contrast, the phylogenetic groups B2, D and F showed a higher predictive virulence score compared to phylogenetic groups A and B1. In conclusion, despite the diversity of E. coli isolates causing UTIs, clonal groups O25:H4-B2-ST131 H30-R, O1:H6-B2-ST648, and O102:H6-D-ST405 were the most prevalent. The emergence of highly virulent and MDR E. coli in Brazil is of high concern and requires more attention from the health authorities.

Positive impact of infection prevention on the management of nosocomial outbreaks at an academic hospital.

AIM: Infection prevention (IP) measures are vital to prevent (nosocomial) outbreaks. Financial evaluations of these are scarce. An incremental cost analysis for an academic IP unit was performed. MATERIAL & METHODS: On a yearly basis, we evaluated: IP measures; costs thereof; numbers of patients at risk for causing nosocomial outbreaks; predicted outbreak patients; and actual outbreak patients. RESULTS: IP costs rose on average yearly with €150,000; however, more IP actions were undertaken. Numbers of patients colonized with high-risk microorganisms increased. The trend of actual outbreak patients remained stable. Predicted prevented outbreak patients saved costs, leading to a positive return on investment of 1.94. CONCLUSION: This study shows that investments in IP can prevent outbreak cases, thereby saving enough money to earn back these investments.

Cross-border comparison of antibiotic prescriptions among children and adolescents between the north of the Netherlands and the north-west of Germany.

BACKGROUND: Antibiotic resistance is a worldwide problem and inappropriate prescriptions are a cause. Especially among children, prescriptions tend to be high. It is unclear how they differ in bordering regions. This study therefore examined the antibiotic prescription prevalence among children in primary care between northern Netherlands and north-west of Germany. METHODS: Two datasets were used: The Dutch (IADB) comprises representative data of pharmacists in North Netherland and the German (BARMER GEK) includes nationwide health insurance data. Both were filtered using postal codes to define two comparable bordering regions with patients under 18 years for 2010. RESULTS: The proportion of primary care patients receiving at least one antibiotic was lower in northern Netherlands (29.8 %; 95 % confidence interval [95 % CI]: 29.3-30.3), compared to north-west Germany (38.9 %; 95 % CI: 38.2-39.6). Within the respective countries, there were variations ranging from 27.0 to 44.1 % between different areas. Most profound was the difference in second-generation cephalosporins: for German children 25 % of the total prescriptions, while for Dutch children it was less than 0.1 %. CONCLUSIONS: This study is the first to compare outpatient antibiotic prescriptions among children in primary care practices in bordering regions of two countries. Large differences were seen within and between the countries, with overall higher prescription prevalence in Germany. Considering increasing cross-border healthcare, these comparisons are highly valuable and help act upon antibiotic resistance in the first line of care in an international approach.

Cost-Analysis of Seven Nosocomial Outbreaks in an Academic Hospital.

OBJECTIVES: Nosocomial outbreaks, especially with (multi-)resistant microorganisms, are a major problem for health care institutions. They can cause morbidity and mortality for patients and controlling these costs substantial amounts of funds and resources. However, how much is unclear. This study sets out to provide a comparable overview of the costs of multiple outbreaks in a single academic hospital in the Netherlands. METHODS: Based on interviews with the involved staff, multiple databases and stored records from the Infection Prevention Division all actions undertaken, extra staff employment, use of resources, bed-occupancy rates, and other miscellaneous cost drivers during different outbreaks were scored and quantified into Euros. This led to total costs per outbreak and an estimated average cost per positive patient per outbreak day. RESULTS: Seven outbreaks that occurred between 2012 and 2014 in the hospital were evaluated. Total costs for the hospital ranged between €10,778 and €356,754. Costs per positive patient per outbreak day, ranged between €10 and €1,369 (95% CI: €49-€1,042), with a mean of €546 and a median of €519. Majority of the costs (50%) were made because of closed beds. CONCLUSIONS: This analysis is the first to give a comparable overview of various outbreaks, caused by different microorganisms, in the same hospital and all analyzed with the same method. It shows a large variation within the average costs due to different factors (e.g. closure of wards, type of ward). All outbreaks however cost considerable amounts of efforts and money (up to €356,754), including missed revenue and control measures.

An integrated stewardship model: antimicrobial, infection prevention and diagnostic (AID).

Considering the threat of antimicrobial resistance and the difficulties it entails in treating infections, it is necessary to cross borders and approach infection management in an integrated, multidisciplinary manner. We propose the antimicrobial, infection prevention and diagnostic stewardship model comprising three intertwined programs: antimicrobial, infection prevention and diagnostic stewardship, involving all stakeholders. The focus is a so-called 'theragnostics' approach. This leads to a personalized infection management plan, improving patient care and minimizing resistance development. Furthermore, it is important that healthcare regions nationally and internationally work together, ensuring that the patient (and microorganism) transfers will not cause problems in a neighboring institution. This antimicrobial, infection prevention and diagnostic stewardship model can serve as a blue print to implement innovative, integrative infection management.

Impact of non-anastomotic biliary strictures after liver transplantation on healthcare consumption, use of ionizing radiation and infectious events.

BACKGROUND: Non-anastomotic biliary strictures (NAS) after orthotopic liver transplantation (OLT) have a negative influence on graft survival. Expert opinion suggests a negative effect of NAS on other important aspects of post-transplant care, although its impact is largely unknown as data are scarce. METHODS: This retrospective single center study analyzed data on healthcare consumption, use of ionizing radiation, infectious complications and development of highly resistant microorganisms (HRMO) in adult patients with NAS. A comparison with a matched control group was made. RESULTS: Forty-three liver recipients with NAS and 43 controls were included. Hospital admissions were higher in patients with NAS. Most common reason for admission was bacterial cholangitis (BC), with 70% of the patients having at least one episode compared to 9% in the control group. In patients with NAS, 67% received at least one ERCP compared to 21% in the control group (p = 0.001). This resulted in a larger yearly received radiation dose for patients with NAS (p = 0.001). Frequency of intravenous antibiotic therapy was higher (p = 0.001) for patients with NAS, consistently resulting in a higher number of cultures found with HRMO (p = 0.012). CONCLUSION: NAS after OLT have a negative effect on post-transplant care, increasing readmission rates, interventional procedures, exposure to ionizing radiation, use of antibiotics, and development of HRMO.

Automatic day-2 intervention by a multidisciplinary antimicrobial stewardship-team leads to multiple positive effects.

BACKGROUND: Antimicrobial resistance rates are increasing. This is, among others, caused by incorrect or inappropriate use of antimicrobials. To target this, a multidisciplinary antimicrobial stewardship-team (A-Team) was implemented at the University Medical Center Groningen on a urology ward. Goal of this study is to evaluate the clinical effects of the case-audits done by this team, looking at length of stay (LOS) and antimicrobial use. METHODS: Automatic e-mail alerts were sent after 48 h of consecutive antimicrobial use triggering the case-audits, consisting of an A-Team member visiting the ward, discussing the patient's therapy with the bed-side physician and together deciding on further treatment based on available diagnostics and guidelines. Clinical effects of the audits were evaluated through an Interrupted Time Series analysis and a retrospective historic cohort. RESULTS: A significant systemic reduction of antimicrobial consumption for all patients on the ward, both with and without case-audits was observed. Furthermore, LOS for patients with case-audits who were admitted primarily due to infections decreased to 6.20 days (95% CI: 5.59-6.81) compared to the historic cohort (7.57 days; 95% CI: 6.92-8.21; p = 0.012). Antimicrobial consumption decreased for these patients from 8.17 DDD/patient (95% CI: 7.10-9.24) to 5.93 DDD/patient (95% CI: 5.02-6.83; p = 0.008). For patients with severe underlying diseases (e.g., cancer) these outcome measures remained unchanged. CONCLUSION: The evaluation showed a considerable positive impact. Antibiotic use of the whole ward was reduced, transcending the intervened patients. Furthermore, LOS and mean antimicrobial consumption for a subgroup was reduced, thereby improving patient care and potentially lowering resistance rates.

Financial evaluations of antibiotic stewardship programs-a systematic review.

INTRODUCTION: There is an increasing awareness to counteract problems due to incorrect antimicrobial use. Interventions that are implemented are often part of an Antimicrobial Stewardship Program (ASPs). Studies publishing results from these interventions are increasing, including reports on the economical effects of ASPs. This review will look at the economical sections of these studies and the methods that were used. METHODS: A systematic review was performed of articles found in the PubMed and EMBASE databases published from 2000 until November 2014. Included studies found were scored for various aspects and the quality of the papers was assessed following an appropriate check list (CHEC criteria list). RESULTS: 1233 studies were found, of which 149 were read completely. Ninety-nine were included in the final review. Of these studies, 57 only mentioned the costs associated with the antimicrobial medication. Others also included operational costs (n = 23), costs for hospital stay (n = 18), and/or other costs (n = 19). Nine studies were further assessed for their quality. These studies scored between 2 and 14 out of a potential total score of 19. CONCLUSIONS: This review gives an extensive overview of the current financial evaluation of ASPs and the quality of these economical studies. We show that there is still major potential to improve financial evaluations of ASPs. Studies do not use similar nor consistent methods or outcome measures, making it impossible draw sound conclusions and compare different studies. Finally, we make some recommendations for the future.

Cost-minimization model of a multidisciplinary antibiotic stewardship team based on a successful implementation on a urology ward of an academic hospital.

BACKGROUND: In order to stimulate appropriate antimicrobial use and thereby lower the chances of resistance development, an Antibiotic Stewardship Team (A-Team) has been implemented at the University Medical Center Groningen, the Netherlands. Focus of the A-Team was a pro-active day 2 case-audit, which was financially evaluated here to calculate the return on investment from a hospital perspective. METHODS: Effects were evaluated by comparing audited patients with a historic cohort with the same diagnosis-related groups. Based upon this evaluation a cost-minimization model was created that can be used to predict the financial effects of a day 2 case-audit. Sensitivity analyses were performed to deal with uncertainties. Finally, the model was used to financially evaluate the A-Team. RESULTS: One whole year including 114 patients was evaluated. Implementation costs were calculated to be €17,732, which represent total costs spent to implement this A-Team. For this specific patient group admitted to a urology ward and consulted on day 2 by the A-Team, the model estimated total savings of €60,306 after one year for this single department, leading to a return on investment of 5.9. CONCLUSIONS: The implemented multi-disciplinary A-Team performing a day 2 case-audit in the hospital had a positive return on investment caused by a reduced length of stay due to a more appropriate antibiotic therapy. Based on the extensive data analysis, a model of this intervention could be constructed. This model could be used by other institutions, using their own data to estimate the effects of a day 2 case-audit in their hospital.

Paediatric nodal marginal zone B-cell lymphadenopathy of the neck: a Haemophilus influenzae-driven immune disorder?

Many hyperplasias and lymphomas of marginal zone B-cells are associated with infection. We identified six children and one adolescent with cervical lymphadenopathy showing prominent polyclonal nodal marginal zone hyperplasia (pNMZH) and four adolescents with monoclonal paediatric nodal marginal zone lymphoma (pNMZL). The clonality status was assessed using BIOMED-2-IG PCR analysis. Haemophilus influenzae was identified in all six cases of pNMZH that could be tested by direct culture (N = 3) or a very sensitive PCR for the H. influenzae gyrase gene in frozen materials (N = 5). H. influenzae was not detected in three pNMZLs and 28 non-specific reactive cervical lymph nodes of age-matched controls, except for a single control node that was obtained during oropharyngeal surgery for a cleft palate showing very low copy numbers of H. influenzae. pNMZH patients were younger than pNMZL patients (median age 12 versus 21 years). pNMZH showed a prominent nodular appearance with variable fibrosis without acute inflammation. Within the nodules, the expanded germinal centres and variably sized marginal zones were colonized by activated B-cells with weak expression of IgD and lack of CD10 and/or BCL6 expression. Some areas showed skewed light chain expression in plasma cells (4/5 cases lambda). In four cases tested, this was confirmed by flow cytometry for surface Ig (3/4 cases lambda). In contrast, pNMZL showed more extensive expansion of marginal zones by centrocytoid cells and often expression of BCL2 protein. Several H. influenzae strains are known to interact with the constant part of IgD on human B-cells, leading to their polyclonal proliferation and activation. We speculate that in vivo stimulation of IgD+ marginal zone B-cells by this bacterium may be implicated in this particular lymphadenopathy that should be distinguished from monoclonal pNMZL.

Evaluation of early implementations of antibiotic stewardship program initiatives in nine Dutch hospitals.

BACKGROUND: Antibiotic resistance is a global threat to patient safety and care. In response, hospitals start antibiotic stewardship programs to optimise antibiotic use. Expert-based guidelines recommend strategies to implement such programs, but local implementations may differ per hospital. Earlier published assessments determine maturity of antibiotic stewardship programs based on expert-based structure indicators, but they disregard that there may be valid deviations from these expert-based programs. AIM: To analyse the progress and barriers of local implementations of antibiotic stewardship programs with stakeholders in nine Dutch hospitals and to develop a toolkit that guides implementing local antibiotic stewardship programs. METHODS: An online questionnaire based on published guidelines and recommendations, conducted with seven clinical microbiologists, seven infectious disease physicians and five clinical pharmacists at nine Dutch hospitals. RESULTS: Results show local differences in antibiotic stewardship programs and the uptake of interventions in hospitals. Antibiotic guidelines and antibiotic teams are the most extensively implemented interventions. Education, decision support and audit-feedback are deemed important interventions and they are either piloted in implementations at academic hospitals or in preparation for application in non-academic hospitals. Other interventions that are recommended in guidelines - benchmarking, restriction and antibiotic formulary - appear to have a lower priority. Automatic stop-order, pre-authorization, automatic substitution, antibiotic cycling are not deemed to be worthwhile according to respondents. CONCLUSION: There are extensive local differences in the implementation of antibiotic stewardship interventions. These differences suggest a need to further explore the rationale behind the choice of interventions in antibiotic stewardship programs. Rather than reporting this rationale, this study reports where rationale can play a key role in the implementation of antibiotic stewardship programs. A one-size-fits-all solution is unfeasible as there may be barriers or valid reasons for local experts to deviate from expert-based guidelines. Local experts can be supported with a toolkit containing advice based on possible barriers and considerations. These parameters can be used to customise an implementation of antibiotic stewardship programs to local needs (while retaining its expert-based foundation).

[Bedside consultation by a multidisciplinary antibiotics team: an Antibiotic Stewardship Programme at UMCG]. / 'Bedside'-consultatie door multidisciplinair Antibiotica-team: 'Antimicrobial stewardship'-programma in het UMCG.

In 2012, the Dutch Working Party on Antibiotic Policy (SWAB) published a vision document to counteract the rise in antibiotic use and resistance. An Antibiotic Stewardship Programme (ASP) will be implemented by a multidisciplinary antibiotics team (A-team). In 2012 University Medical Centre Groningen (UMCG) in the Netherlands started an Antibiotic Stewardship Programme (ASP) pilot project at the trauma surgery ward. The focus is on providing bedside consultation for patients based on the day 2 bundle. Implementation of the ASP on the basis of a day 2 bundle resulted in an intervention percentage of 75%. The pilot project was a success and will be extended to other wards.

Double-stranded RNA mycovirus infection of Aspergillus fumigatus is not dependent on the genetic make-up of the host.

Aspergillus fumigatus is a fungus that causes opportunistic infections in immunocompromised patients, with high morbidity and mortality. In its turn, A. fumigatus can become infected with mycoviruses. Most mycoviruses have a dsRNA genome and can cause fungal hypovirulence. For that reason, mycoviruses could theoretically be used as therapeutic tools to combat fungal infections. We determined if a certain genetic make-up of A. fumigatus was associated with the presence of mycoviruses in 86 clinical A. fumigatus isolates. Mycovirus screening was performed by isolating dsRNA from mycelial cultures using a Trizol/Chloroform method. The genetic relatedness of dsRNA infected A. fumigatus was determined by cell surface protein (CSP) typing and determination of the mating type. Sixteen (18.6%) of the 86 clinical A. fumigatus isolates contained dsRNA. The A. fumigatus collection could be divided into 11 different CSP types. DsRNA infected A. fumigatus isolates had similar CSP types as non-infected isolates. In both cases, the CSP types t01, t02, t03 and t04 were the most prevalent and the distribution comparable to the CSP types observed in other Dutch collections. Mating types MAT1-1 and MAT1-2 were evenly distributed among all A. fumigatus strains, regardless of CSP type. No difference was observed in mycovirus infections between MAT1-1 and MAT1-2 isolates. DsRNA mycovirus infections in A. fumigatus are not related to either CSP or mating type and therefore represent an interesting future therapeutic tool to combat fungal infections.

Cost-effectiveness of a screening strategy for Q fever among pregnant women in risk areas: a clustered randomized controlled trial.

BACKGROUND: In The Netherlands the largest human Q fever outbreak ever reported in the literature is currently ongoing with more than 2300 notified cases in 2009. Pregnant women are particularly at risk as Q fever during pregnancy may cause maternal and obstetric complications. Since the majority of infected pregnant women are asymptomatic, a screening strategy might be of great value to reduce Q fever related complications. We designed a trial to assess the (cost-)effectiveness of a screening program for Q fever in pregnant women living in risks areas in The Netherlands. METHODS/DESIGN: We will conduct a clustered randomized controlled trial in which primary care midwife centres in Q fever risk areas are randomized to recruit pregnant women for either the control group or the intervention group. In both groups a blood sample is taken around 20 weeks postmenstrual age. In the intervention group, this sample is immediately analyzed by indirect immunofluorescence assay for detection of IgG and IgM antibodies using a sensitive cut-off level of 1:32. In case of an active Q fever infection, antibiotic treatment is recommended and serological follow up is performed. In the control group, serum is frozen for analysis after delivery. The primary endpoint is a maternal (chronic Q fever or reactivation) or obstetric complication (low birth weight, preterm delivery or fetal death) in Q fever positive women. Secondary aims pertain to the course of infection in pregnant women, diagnostic accuracy of laboratory tests used for screening, histo-pathological abnormalities of the placenta of Q fever positive women, side effects of therapy, and costs. The analysis will be according to the intention-to-screen principle, and cost-effectiveness analysis will be performed by comparing the direct and indirect costs between the intervention and control group. DISCUSSION: With this study we aim to provide insight into the balance of risks of undetected and detected Q fever during pregnancy. TRIAL REGISTRATION: ClinicalTrials.gov, protocol record NL30340.042.09.

Disseminated Rhodococcus equi infection in a kidney transplant patient without initial pulmonary involvement.

Rhodococcus equi is increasingly recognized as an opportunistic pathogen in solid organ transplant recipients. Primary pulmonary involvement is the most common finding. We report a case of a 42-year-old female kidney transplant recipient who developed multiple disseminated abscesses caused by R. equi while on adequate antimicrobial therapy. The patient presented with subcutaneous abscesses in the hip region and mamma and had 2 intracerebral abscesses. There were no clinical and radiologic signs of pulmonary involvement in contrast to most clinical cases described in the literature. R. equi was cultured from all abscesses. The patient died of progressive neurologic complications. Post mortem examination confirmed infection with R. equi and showed microscopic evidence of necrotizing pneumonia. This report shows that R. equi should be considered as a cause of infection in solid organ transplant recipients even without initial clinical and radiologic signs of pulmonary involvement. Despite adequate therapy, the outcome can be fatal.

Comparative evaluation of the VITEK 2, disk diffusion, etest, broth microdilution, and agar dilution susceptibility testing methods for colistin in clinical isolates, including heteroresistant Enterobacter cloacae and Acinetobacter baumannii strains.

Increasing antibiotic resistance in gram-negative bacteria has recently renewed interest in colistin as a therapeutic option. The increasing use of colistin necessitates the availability of rapid and reliable methods for colistin susceptibility testing. We compared seven methods of colistin susceptibility testing (disk diffusion, agar dilution on Mueller-Hinton [MH] and Isosensitest agar, Etest on MH and Isosensitest agar, broth microdilution, and VITEK 2) on 102 clinical isolates collected from patient materials during a selective digestive decontamination or selective oral decontamination trial in an intensive-care unit. Disk diffusion is an unreliable method to measure susceptibility to colistin. High error rates and low levels of reproducibility were observed in the disk diffusion test. The colistin Etest, agar dilution, and the VITEK 2 showed a high level of agreement with the broth microdilution reference method. Heteroresistance for colistin was observed in six Enterobacter cloacae isolates and in one Acinetobacter baumannii isolate. This is the first report of heteroresistance to colistin in E. cloacae isolates. Resistance to colistin in these isolates seemed to be induced upon exposure to colistin rather than being caused by stable mutations. Heteroresistant isolates could be detected in the broth microdilution, agar dilution, Etest, or disk diffusion test. The VITEK 2 displayed low sensitivity in the detection of heteroresistant subpopulations of E. cloacae. The VITEK 2 colistin susceptibility test can therefore be considered to be a reliable tool to determine susceptibility to colistin in isolates of genera that are known not to exhibit resistant subpopulations. In isolates of genera known to (occasionally) exhibit heteroresistance, an alternative susceptibility testing method capable of detecting heteroresistance should be used.