A global view on carbapenem-resistant Acinetobacter baumannii

To give an update on the molecular epidemiology and global distribution of carbapenemase encoding genes, we subjected 313 carbapenem-resistant Acinetobacter baumannii isolated from 114 study centers in 47 countries in five world regions, Africa, Asia, Europe, Latin America, and North America, to whole genome sequencing. Numbers of isolates investigated were proportional to the population size of the contributing countries. Molecular epidemiology was investigated using seven-loci and core genome multilocus sequence typing, whole-genome single nucleotide polymorphism phylogenies, and the intrinsic blaOXA-51-like variant. Carbapenemase encoding genes were identified by multiplex PCR and ResFinder. Among the total of 313 isolates, 289 (92.3%) were assigned to A. baumannii international clones (IC) IC1-IC8. IC2 predominated with 196 isolates (62.6%) and was spread worldwide, followed by IC5 with 44 isolates (14.1%) mainly confined to Latin America. Six isolates (1.9%) originating from Belgium, Egypt, Italy, and Pakistan represent the novel IC9. Acquired OXA-type carbapenemase genes were found in 300 (96%) isolates with blaOXA-23-like and blaOXA-40-like predominating, which constitutes a significant increase compared to our findings from 2010. Metallo-beta-lactamases were rare with seven isolates (2.2%). The distribution of ICs and carbapenemase determinants can vary widely among different geographical regions. IMPORTANCE Carbapenem-resistant Acinetobacter baumannii are of increasing public health importance, as they are resistant to last-line antibiotics. International clones with well-characterized resistance genes dominate globally; however, locally, other lineages with different properties may be of importance to consider. This study investigated isolates from a broad geographic origin from 114 hospitals in 47 countries and from five world regions ensuring the greatest possible diversity in an organism known for its propensity for clonal epidemic spread and reflecting the current global epidemiology of carbapenem-resistant A. baumannii. In Latin America, a lineage different from other geographic regions circulates, with a different resistance gene profile. This knowledge is important to adjust local infection prevention measures. In a global world with migration and increasing use of antimicrobials, multidrug-resistant bacteria will continue to adapt and challenge our healthcare systems worldwide.

Dupuytren's Disease Is Mediated by Insufficient TGF-β1 Release and Degradation

Dupuytren's disease (DD) is a fibroproliferative disorder affecting the palmar fascia, causing functional restrictions of the hand and thereby limiting patients' daily lives. The disturbed and excessive myofibroblastogenesis, causing DD, is mainly induced by transforming growth factor (TGF)-β1. But, the extent to which impaired TGF-β1 release or TGF-β signal degradation is involved in pathologically altered myofibroblastogenesis in DD has been barely examined. Therefore, the complex in which TGF-β1 is secreted in the extracellular matrix to elicit its biological activity, and proteins such as plasmin, integrins, and matrix metalloproteinases (MMPs), which are involved in the TGF-β1 activation, were herein analyzed in DD-fibroblasts (DD-FBs). Additionally, TGF-β signal degradation via caveolin-1 was examined with 5-fluoruracil (5-FU) in detail. Gene expression analysis was performed via Western blot, PCR, and immunofluorescence analyses. As a surrogate parameter for disturbed myofibroblastogenesis, 𝛼-smooth-muscle-actin (𝛼-SMA) expression was evaluated. It was demonstrated that latency-associated peptide (LAP)-TGF-β and latent TGF-β-binding protein (LTBP)-1 involved in TGF-β-complex building were significantly upregulated in DD. Plasmin a serinprotease responsible for the TGF-β release was significantly downregulated. The application of exogenous plasmin was able to inhibit disturbed myofibroblastogenesis, as measured via 𝛼-SMA expression. Furthermore, a reduced TGF-β1 degradation was also involved in the pathological phenotype of DD, because caveolin-1 expression was significantly downregulated, and if rescued, myofibroblastogenesis was also inhibited. Therefore, our study demonstrates that a deficient release and degradation of TGF-β1 are important players in the pathological phenotype of DD and should be addressed in future research studies to improve DD therapy or other related fibrotic conditions.

Carbapenem resistance in Acinetobacter pittii isolates mediated by metallo-β-lactamases

OBJECTIVES

To characterize the genetic environment of metallo-β-lactamases (MBL) in carbapenem-resistant clinical Acinetobacter pittii isolates.

METHODS

Seventeen carbapenem-resistant A. pittii isolates harbouring an MBL were collected between 2010 and 2015 in Germany. Antimicrobial susceptibility testing was performed using agar dilution. Presence of MBLs was confirmed by PCR and their genetic location determined by S1-pulsed-field gel electrophoresis followed by Southern blot hybridization. Whole-genome sequencing was performed using the Miseq and MinION platforms. Isolates were typed using an ad hoc core genome MLST scheme. Conjugation into A. baumannii was tested by broth mating.

RESULTS

In 10 isolates the MBL was plasmid-encoded and in seven isolates chromosomally encoded. blaGIM-1 and blaVIM-2 were plasmid-encoded, blaVIM-4 was chromosomally encoded, while blaNDM-1 was chromosomally encoded in four and plasmid-encoded in three isolates. Seven of ten plasmids were conjugative into A. baumannii. Although most isolates were unrelated, the backbones of the MBL-encoding plasmid showed >99% similarity and only differed in the MBL-encoding area. blaNDM-1-harbouring plasmids were highly similar to other plasmids from Acinetobacter isolates worldwide while the blaVIM-2- and blaGIM-1-encoding plasmids have not been described.

CONCLUSIONS

These data show the existence of a promiscuous plasmid circulating in A. pittii isolates in Germany that differs only in the MBL-encoding region. Its plasmid backbone has been found globally among multiple Acinetobacter spp. These data should raise awareness of an epidemic conjugative plasmid that has independently acquired MBLs. We should also consider that future comparative plasmid analysis will look beyond solely the resistome and include the mobile elements carrying the resistance genes.

Klebsiella pneumonia in Sudan: Multidrug Resistance, Polyclonal Dissemination, and Virulence

The emergence and global expansion of hyper-virulent and multidrug resistant (MDR) Klebsiella pneumoniae is an increasing healthcare threat worldwide. The epidemiology of MDR K. pneumoniae is under-characterized in many parts of the world, particularly Africa. In this study, K. pneumoniae isolates from hospitals in Khartoum, Sudan, have been whole-genome sequenced to investigate their molecular epidemiology, virulence, and resistome profiles. Eighty-six K. pneumoniae were recovered from patients in five hospitals in Khartoum between 2016 and 2020. Antimicrobial susceptibility was performed by disk-diffusion and broth microdilution. All isolates underwent whole genome sequencing using Illumina MiSeq; cgMLST was determined using Ridom SeqSphere+, and 7-loci MLST virulence genes and resistomes were identified. MDR was observed at 80%, with 35 isolates (41%) confirmed carbapenem-resistant. Thirty-seven sequence types were identified, and 14 transmission clusters (TC). Five of these TCs involved more than one hospital. Ybt9 was the most common virulence gene detected, in addition to some isolates harbouring iuc and rmp1. There is a diverse population of K. pneumoniae in Khartoum hospitals, harbouring multiple resistance genes, including genes coding for ESBLs, carbapenemases, and aminoglycoside-modifying enzymes, across multiple ST's. The majority of isolates were singletons and transmissions were rare.

Resolving colistin resistance and heteroresistance in Enterobacter species

Species within the Enterobacter cloacae complex (ECC) include globally important nosocomial pathogens. A three-year study of ECC in Germany identified Enterobacter xiangfangensis as the most common species (65.5%) detected, a result replicated by examining a global pool of 3246 isolates. Antibiotic resistance profiling revealed widespread resistance and heteroresistance to the antibiotic colistin and detected the mobile colistin resistance (mcr)-9 gene in 19.2% of all isolates. We show that resistance and heteroresistance properties depend on the chromosomal arnBCADTEF gene cassette whose products catalyze transfer of L-Ara4N to lipid A. Using comparative genomics, mutational analysis, and quantitative lipid A profiling we demonstrate that intrinsic lipid A modification levels are genospecies-dependent and governed by allelic variations in phoPQ and mgrB, that encode a two-component sensor-activator system and specific inhibitor peptide. By generating phoPQ chimeras and combining them with mgrB alleles, we show that interactions at the pH-sensing interface of the sensory histidine kinase phoQ dictate arnBCADTEF expression levels. To minimize therapeutic failures, we developed an assay that accurately detects colistin resistance levels for any ECC isolate.

The evolution of carbapenem resistance determinants and major epidemiological lineages among carbapenem-resistant Acinetobacter baumannii isolates in Germany, 2010-2019

The aim of this study was to investigate and compare the molecular epidemiology and carbapenem resistance determinants in clinical Acinetobacter baumannii isolates collected during four multicentre surveillance studies conducted by the Paul-Ehrlich-Society for Infection Therapy. Isolates were collected prospectively from hospital in-patients at 17 medical centres in Germany over four periods of three- to six-months starting in October of each of 2010, 2013, 2016 and 2019. Species identification was performed by MALDI-TOF, gyrB multiplex polymerase chain reaction (PCR), and detection of the intrinsic bla_OXA-51-like gene. Minimum inhibitory concentrations were determined by broth microdilution. The prevalence of carbapenemase-encoding genes was investigated by OXA-multiplex PCR and whole-genome sequencing. Molecular epidemiology was examined by rep-PCR and core-genome multi-locus sequence typing. A total of 302 A. baumannii isolates were collected. Resistance to imipenem and/or meropenem was detected in 58 isolates (19.2%) from 14 centres. The proportion of carbapenem-resistant isolates increased from 21.3% in 2010 to 33.3% in 2013, and then decreased to 13.8% in 2016 and 12.3% in 2019. Forty-six of these isolates were associated with the international clonal lineage IC2 and five with IC1. The most prevalent carbapenemase gene detected was bla_OXA-23-like (n=51). Further carbapenem-resistance determinants were bla_OXA-40-like (n=1), bla_OXA-58-like (n=3) and bla_NDM-1 (n=2). In one isolate, ISAba1 was detected upstream of bla_OXA-51-like. In conclusion, IC2 was the most prevalent clonal lineage detected in this study. Interestingly, in Germany, carbapenem resistance seems to have decreased in A. baumannii between 2013 and 2019.

Surveillance and Genomic Analysis of Third-Generation Cephalosporin-Resistant and Carbapenem-Resistant Klebsiella pneumoniae Complex in Germany

To analyse the epidemiology and population structure of third-generation cephalosporin-resistant (3GCR) and carbapenem-resistant (CR) Klebsiella pneumoniae complex isolates, patients were screened for rectal colonisation with 3GCR/CR K. pneumoniae complex on admission to six German university hospitals (2016–2019). Also collected were 3GCR/CR and susceptible K. pneumoniae isolates from patients with bloodstream infections (2016–2018). Whole-genome sequencing was performed followed by multilocus sequencing typing (MLST), core-genome MLST, and resistome and virulome analysis. The admission prevalence of 3GCR K. pneumoniae complex isolates during the 4-year study period was 0.8%, and 1.0 bloodstream infection per 1000 patient admissions was caused by K. pneumoniae complex (3GCR prevalence, 15.1%). A total of seven K. pneumoniae complex bloodstream isolates were CR (0.8%). The majority of colonising and bloodstream 3GCR isolates were identified as K. pneumoniae, 96.7% and 98.8%, respectively; the remainder were K. variicola and K. quasipneumoniae. cgMLST showed a polyclonal population of colonising and bloodstream isolates, which was also reflected by MLST and virulome analysis. CTX-M-15 was the most prevalent extended-spectrum beta-lactamase, and 29.7% of the colonising and 48.8% of the bloodstream isolates were high-risk clones. The present study provides an insight into the polyclonal 3GCR K. pneumoniae population in German hospitals.

Impact of single-room contact precautions on acquisition and transmission of vancomycin-resistant enterococci on haematological and oncological wards, multicentre cohort-study, Germany, January-December 2016

BackgroundEvidence supporting the effectiveness of single-room contact precautions (SCP) in preventing in-hospital acquisition of vancomycin-resistant enterococci (haVRE) is limited.AimWe assessed the impact of SCP on haVRE and their transmission.MethodsWe conducted a prospective, multicentre cohort study in German haematological/oncological departments during 2016. Two sites performed SCP for VRE patients and two did not (NCP). We defined a 5% haVRE-risk difference as non-inferiority margin, screened patients for VRE, and characterised isolates by whole genome sequencing and core genome MLST (cgMLST). Potential confounders were assessed by competing risk regression analysis.ResultsWe included 1,397 patients at NCP and 1,531 patients at SCP sites. Not performing SCP was associated with a significantly higher proportion of haVRE; 12.2% (170/1,397) patients at NCP and 7.4% (113/1,531) patients at SCP sites (relative risk (RR) 1.74; 95% confidence interval (CI): 1.35-2.23). The difference (4.8%) was below the non-inferiority margin. Competing risk regression analysis indicated a stronger impact of antimicrobial exposure (subdistribution hazard ratio (SHR) 7.46; 95% CI: 4.59-12.12) and underlying disease (SHR for acute leukaemia 2.34; 95% CI: 1.46-3.75) on haVRE than NCP (SHR 1.60; 95% CI: 1.14-2.25). Based on cgMLST and patient movement data, we observed 131 patient-to-patient VRE transmissions at NCP and 85 at SCP sites (RR 1.76; 95% CI: 1.33-2.34).ConclusionsWe show a positive impact of SCP on haVRE in a high-risk population, although the observed difference was below the pre-specified non-inferiority margin. Importantly, other factors including antimicrobial exposure seem to be more influential.

OUP accepted manuscript

Objectives

To describe the propensity of carbapenem-resistant Pseudomonas aeruginosa to spread within a hospital critical care setting.

Methods

The study was conducted in a 700-bed tertiary centre in Cologne, Germany. P. aeruginosa resistant to piperacillin, ceftazidime, cefepime, imipenem, meropenem and ciprofloxacin, isolated from clinical and screening specimens from four critical care units from 2015 to 2020 were analysed. Genotyping was carried out by WGS (Illumina and MinION). MLST, core genome MLST (cgMLST) and resistome analysis was performed and merged with epidemiological data.

Results

Fifty-five out of 79 non-duplicate P. aeruginosa isolates were available, of which 20 were carbapenemase producers as follows: bla_VIM-1 (n = 1), bla_VIM-2 (n = 17), bla_VIM-4 (n = 1), and bla_NDM-1/bla_GES-5 (n = 1). Forty-two of 55 isolates were hospital-acquired. cgMLST revealed three clusters: Cluster 1 (n = 15, ST111, bla_VIM-2, recovered between 2015 and 2020); Cluster 2 (n = 4, ST970, carbapenemase negative); and Cluster 3 (n = 2, ST357, carbapenemase negative). The bla_VIM-2 gene of Cluster 1 was integrated on the chromosome in a class 1 integron (type In59). Using conventional epidemiology, we were only able to confirm two patient-to-patient transmissions and one room-to-patient transmission on three different ICUs within Cluster 1. Isolates from Cluster 2 represented an outbreak occurring in 2019.

Conclusions

These data give insight into the epidemiology of carbapenem-resistant P. aeruginosa. Transmission dynamics differed between carbapenemase- and non-carbapenemase-producing isolates. A continuous acquisition of clonally related ST111 VIM-2 P. aeruginosa, being the main carbapenemase-producing strain, was observed over the whole study period, as well as an overall higher genomic diversity among non-carbapenemase-producing P. aeruginosa.

Illuminating the effect of beneficial blue light and ROS-modulating enzymes in Dupuytren's disease

Dupuytren's disease (DD) is a fibroproliferative disorder of the palmar aponeurosis, which is characterized by a compound myofibrogenesis and evidenced by an increased expression of α-smooth muscle actin (α-SMA). In Dupuytren's tissue, higher levels of reactive oxygen species (ROS) are documented, stimulating the proliferation and differentiation of myofibroblasts. Our preliminary study demonstrates that α-SMA-expression is significantly inhibited by blue light irradiation in DD. The objective of this study was to investigate the beneficial effect of blue light irradiation and to elucidate the influence of ROS on myofibrogenesis in the pathogenesis of DD. Therefore, an in-vitro model of human DD fibroblasts was used. DD fibroblasts and control fibroblasts isolated from carpal tunnel syndrome (CTS) were daily irradiated with 40 J/cm2 (λ = 453 nm, 38 mW/cm2). Protein expression of ROS-modulating enzymes (Catalase, NOX4, SOD1, MnSOD) and α-SMA were determined, and additionally analysed after a pharmacological inhibition of the TGF-β1-signaling with SB431542. Furthermore, the protein expression of α-SMA as surrogate parameter for myofibrogenesis was evaluated after applying different concentrations of long-lasting ROS. It could be determined that the beneficial blue light irradiation, which inhibited myofibrogenesis, is mediated by a significant inhibition of catalase protein expression. This effect should be accompanied with an increased intracellular ROS level. Proof of evidence was an H2O2-application on DD fibroblasts, also leading to a decreased myofibrogenesis. Furthermore, it could be demonstrated that endogenous MnSOD was significantly downregulated in resting DD fibroblasts. If DD fibroblasts were treated with the pharmacological inhibitor SB431542, myofibrogenesis was inhibited, but MnSOD expression was simultaneously elevated, which ought to affect ROS level by raising intracellular H2O2 amount. Blue light irradiation as well as the pharmacological action of SB431542 in consequence mediates their beneficial effect on disturbed myofibrogenesis in DD by further increasing ROS level. The present study demonstrates the importance of intracellular ROS homeostasis in DD and illuminates the beneficial effect of blue light as a promising therapy option for DD.

Prevalence of RND efflux pump regulator variants associated with tigecycline resistance in carbapenem-resistant Acinetobacter baumannii from a worldwide survey

OBJECTIVES

To determine the most common tigecycline resistance mechanisms in carbapenem-resistant Acinetobacter baumannii isolates obtained during the global Tigecycline Evaluation Surveillance Trial (TEST).

METHODS

Tigecycline MICs were determined by broth microdilution. WGS was used to screen for the previously identified tigecycline resistance mechanisms, as well as mutations in resistance-nodulation-cell division (RND)-type efflux pump regulators.

RESULTS

From a total 313 isolates, 113 genetically unique tigecycline-resistant isolates were analysed. The most frequent and worldwide distributed mechanism associated with tigecycline resistance was disruption of adeN, which encodes the repressor of the RND efflux pump AdeIJK, either by IS elements or nucleotide deletions causing premature stop codons. However, mutations leading to amino acid substitutions and disruption by IS elements within the two-component regulatory system adeRS, which regulates expression of the AdeABC efflux pump, correlate with higher tigecycline MICs, but these were found less frequently and were mainly restricted to Southern European countries. Furthermore, an altered version of tviB was identified in several tigecycline-resistant isolates that did not have putative resistance mutations within RND-type regulators. The resistance determinants tet(A) and tet(X), as well as resistance mutations in putative resistance determinants trm, plsC, rrf, msbA and genes encoding 30S ribosomal proteins, were not identified in any isolate.

CONCLUSIONS

The most prevalent tigecycline resistance mechanisms were caused by alterations in the regulators of RND-type efflux pumps. These data provide the basis for further characterization of regulator alterations and their contribution to increased efflux and tigecycline resistance, and also should be taken into account in drug discovery programmes to overcome the contribution of efflux pumps.

Characterization of a vancomycin-resistant Enterococcus faecium isolate and a vancomycin-susceptible E. faecium isolate from the same blood culture

OBJECTIVES

To characterize two Enterococcus faecium isolates with different resistance phenotypes obtained from the same blood culture.

METHODS

The isolates were identified by MALDI-TOF MS and antimicrobial susceptibility testing (AST) was performed using a VITEK® 2 AST P592 card and Etest. WGS was performed on the MiSeq and MinION sequencer platforms. Core-genome MLST (cgMLST) and seven-loci MLST were performed. Plasmid analysis was performed using S1-PFGE followed by Southern-blot hybridization.

RESULTS

Both E. faecium isolates were ST203. AST revealed that one was a vancomycin-resistant E. faecium (VREfm) isolate and the other was a vancomycin-susceptible E. faecium (VSEfm) isolate. The VREfm isolate harboured the vanA gene cluster as part of a Tn1546-type transposon encoded on a 49 kb multireplicon (rep1, rep2 and rep7a) plasmid (pAML0157.1). On the same plasmid, ant(6)-Ia, cat-like and erm(B) were encoded. The VSEfm isolate harboured a rep2 plasmid (pAML0158.1), 12 kb in size, which was present in full length as part of pAML0157.1 from the VREfm isolate. The vanA-encoding pAML0157.1 was a chimera of the rep2 pAML0158.1 and a second DNA segment harbouring vanA, ant(6)-Ia, erm(B) and cat-like, as well as the replicons rep1 and rep7a. By cgMLST analysis, the VREfm and VSEfm isolates were identical.

CONCLUSIONS

Our results demonstrate that the VREfm and VSEfm blood culture isolates represented ST203 and were identical. The investigated heterogeneous resistance phenotypes resulted from the acquisition or loss of plasmid segments in the enterococcal isolates. These data illustrate that mobile genetic elements may contribute to the spread of vancomycin resistance among enterococci and to the genotypic and phenotypic variation within clonal isolates.

Molecular Epidemiology of Carbapenem-Resistant Acinetobacter baumannii From Khartoum State, Sudan

Carbapenem resistant Acinetobacter baumannii (CRAb) is an important global pathogen contributing to increased morbidity and mortality in hospitalized patients, due to limited alternative treatment options. Nine international clonal (IC) lineages have been identified in many countries worldwide, however, data still lacks from some parts of the world, particularly in Africa. We hereby present the molecular epidemiology of MDR A. baumannii from four hospitals in Khartoum, Sudan, collected from 2017 to 2018. Forty-two isolates were whole-genome sequenced, and subsequent molecular epidemiology was determined by core genome MLST (cgMLST), and their resistomes identified. All isolates had an array of diverse antibiotic resistance mechanisms conferring resistance to multiple classes of antibiotics. We found a predominance (88%) of IC2 (with the intrinsic OXA-66 and acquired OXA-23), and some with NDM-1. IC2 isolates were sub-divided into 4 STs separated by 5 to 431 allelic differences, and with evidence of seven transmission clusters. Isolates belonging to IC1, IC5, and IC9 were also identified. These data illustrate that MDR IC2 A. baumannii are widely distributed in Khartoum hospitals and are in possession of multiple antibiotic resistance determinants.

Novel multiplex PCRs for detection of the most prevalent carbapenemase genes in Gram-negative bacteria within Germany

Introduction. Gram-negative bacteria are a common source of infection both in hospitals and in the community, and antimicrobial resistance is frequent among them, making antibiotic therapy difficult, especially when these isolates carry carbapenem resistance determinants.Hypothesis/Gap Statement. A simple method to detect all the commonly found carbapenemases in Germany was not available.Aim. The aim of this study was to develop a multiplex PCR for the rapid and reliable identification of the most prevalent carbapenemase-encoding genes in Gram-negative bacteria in Germany.Methodology. Data from the German Gram-negative reference laboratory revealed the most prevalent carbapenemase groups in Germany were (in order of prevalence): bla _VIM, bla _OXA-48, bla _OXA-23, bla _KPC, bla _NDM, bla _OXA-40, bla _OXA-58, bla _IMP, bla _GIM, bla _GES, ISAba1-bla _OXA-51, bla _IMI, bla _FIM and bla _DIM. We developed and tested two multiplex PCRs against 83 carbapenem-resistant Gram-negative clinical isolates. Primers were designed for each carbapenemase group within conserved regions of the encoding genes obtained from publicly available databases. Multiplex-1 included the carbapenemase groups bla _VIM, bla _OXA-48, bla _OXA-23, bla _KPC, bla _NDM and bla _OXA-40, while multiplex-2 included bla _OXA-58, bla _IMP, bla _GIM, bla _GES, ISAba1-bla _OXA-51 and bla _IMI.Results. In the initial evaluation, all but one of the carbapenemases encoded by 75 carbapenemase-positive isolates were detected using the two multiplex PCRs, while no false-positive results were obtained from the remaining eight isolates. After evaluation, we tested 546 carbapenem-resistant isolates using the multiplex PCRs, and all carbapenemases were detected.Conclusion. A rapid and reliable method was developed for detection and differentiation of 12 of the most prevalent carbapenemase groups found in Germany. This method allows for the rapid testing of clinical isolates prior to species identification and does not require prior phenotypical characterization, constituting a rapid and valuable tool in the management of infections in hospitals.

Clinical Impact of Rapid Species Identification From Positive Blood Cultures With Same-day Phenotypic Antimicrobial Susceptibility Testing on the Management and Outcome of Bloodstream Infections

BACKGROUND

Timely availability of microbiological results from positive blood cultures is essential to enable early pathogen-directed therapy. The Accelerate Pheno system (ADX) is a novel technology using fluorescence in situ hybridization for rapid species identification (ID) and morphokinetic bacterial analysis for phenotypic antimicrobial susceptibility testing (AST), with promising results. Yet the impact of this technology on clinical management and patient outcome remains unclear.

METHODS

We conducted a quasiexperimental before-and-after observational study and analyzed 3 groups with different diagnostic and therapeutic pathways following recent integration of ADX: conventional microbiological diagnostics with and without antimicrobial stewardship program (ASP) intervention, and rapid diagnostics (ADX in addition to conventional standard) with ASP intervention. Primary endpoints were time to adequate, to optimal and to step-down antimicrobial therapy. Secondary endpoints were antimicrobial consumption, in-hospital mortality, length of stay (LOS), and the incidence of Clostridioidesdifficile infection (CDI).

RESULTS

Two hundred four patients (conventional diagnostics, n = 64; conventional diagnostics + ASP, n = 68; rapid diagnostics + ASP; n = 72) were evaluated. The use of ADX significantly decreased time from Gram stain to ID (median, 23 vs 2.2 hours, P < .001) and AST (median, 23 vs 7.4 hours, P < .001), from Gram stain to optimal therapy (median, 11 vs 7 hours, P = .024) and to step-down antimicrobial therapy (median, 27.8 vs 12 hours, P = .019). However, groups did not differ in antimicrobial consumption, duration of antimicrobial therapy, mortality, LOS, or incidence of CDI.

CONCLUSIONS

Use of ADX significantly reduced time to ID and AST as well as time to optimal antimicrobial therapy but did not affect antimicrobial consumption and clinical outcome.

Genomic Analysis of Carbapenem-Resistant Acinetobacter baumannii Isolates Belonging to Major Endemic Clones in South America

Carbapenem-resistant Acinetobacter baumannii (CRAB) are emerging worldwide. In South America, clinical isolates presenting such a phenotype usually do not belong to the globally distributed international clone 2 (IC2). The majority of these isolates are also resistant to multiple other antimicrobials and are often designated extremely drug-resistant (XDR). The aim of this study was to characterize the resistance mechanisms presented by 18 carbapenem-resistant A. baumannii isolates from five different Brazilian hospitals. Species identification was determined by rpoB sequencing, and antimicrobial susceptibility was determined by broth microdilution. Isolates were submitted to whole genome sequencing using Illumina platform and genetic similarity was determined by PFGE, MLST, and cgMLST. Genome analysis was used to identify intrinsic and acquired resistance determinants, including mutations in the AdeRSABC efflux system and in outer membrane proteins (OMPs). All isolates were identified as A. baumannii and grouped into 4 pulsotypes by PFGE, which belonged to clonal complexes (CC) 15^Pas/103^Ox (n = 4) and 79^Pas/113^Ox (n = 14), corresponding to IC4 and IC5, respectively. High MIC values to carbapenems, broad-spectrum cephalosporins, amikacin, and ciprofloxacin were observed in all isolates, while MICs of ampicillin/sulbactam, gentamicin, and tigecycline varied among the isolates. Minocycline was the most active antimicrobial agent tested. Moreover, 12 isolates (66.7%) were considered resistant to polymyxins. Besides intrinsic OXA-51 and ADC variants, all isolates harbored an acquired carbapenem-hydrolyzing class D β-lactamase (CHDL) encoding gene, either bla_OXA–23 or bla_OXA–72. A diversity of aminoglycoside modifying enzymes and resistance determinants to other antimicrobial classes were found, as well as mutations in gyrA and parC. Non-synonymous mutations have also been identified in the AdeRSABC efflux system and in most OMPs, but they were considered natural polymorphisms. Moreover, resistance to polymyxins among isolates belonging to IC5 were associated to non-synonymous mutations in pmrB, but no known polymyxin resistance mechanism was identified in isolates belonging to IC4. In conclusion, A. baumannii clinical isolates belonging to South America’s major clones present a myriad of antimicrobial resistance determinants. Special attention should be paid to natural polymorphisms observed in each clonal lineage, especially regarding non-synonymous mutations in constitutive genes associated with distinct resistance phenotypes.

First Report of New Delhi Metallo-β-Lactamase-6 (NDM-6) in a Clinical Acinetobacter baumannii Isolate From Northern Spain

The objective of this study was the phenotypic and genotypic characterization of a carbapenem resistant Acinetobacter baumannii (CRAB) isolate. The isolate, recovered in Northern Spain in 2019, was identified by MALDI-TOF to the species level. Antimicrobial susceptibility testing was performed using the Phoenix BD NMIC-502 Panel, E-test, and broth microdilution methods. The presence of a metallo-β-lactamase (MBL) was verified by PCR and immunochromatographic assays. The genetic location of the MBL was confirmed using S1-pulsed-field gel electrophoresis (S1-PFGE) followed by Southern blot hybridization. Whole genome sequencing (WGS) was completed using the Miseq and MinION platforms, followed by core-genome MLST (cgMLST) and seven-locus MLST analysis. The CRAB was assigned ST85 (Pasteur scheme) and ST957 (Oxford scheme) representing international clone (IC) 9 and harbored the intrinsic β-lactamase OXA-94 with ISAba1 upstream of it, and the MBL bla _NDM-6. Hybridization experiments revealed that the bla _NDM-6 was encoded on the chromosome. Using WGS the bla _NDM-6 environment could be identified arranged in the following order: ISAba14, aphA6, ISAba125, bla _NDM-6, ble _MBL, trpF, dsbC, cutA, and ISAba14. Downstream, a 10,462 bp duplication was identified, including a second copy of bla _NDM-6 in the following genetic composition: ISAba125, bla _NDM-6, ble _MBL, trpF, dsbC, cutA, and ISAba14. To our knowledge, this is the first description of bla _NDM-6 in A. baumannii. The MBL was present in two copies in the chromosome in a new genetic environment associated with IS elements highlighting the contribution of mobile genetic elements in the dissemination of this gene.

Mobile Genetic Elements Harboring Antibiotic Resistance Determinants in Acinetobacter baumannii Isolates From Bolivia

Using a combination of short- and long-read DNA sequencing, we have investigated the location of antibiotic resistance genes and characterized mobile genetic elements (MGEs) in three clinical multi-drug resistant Acinetobacter baumannii. The isolates, collected in Bolivia, clustered separately with three different international clonal lineages. We found a diverse array of transposons, plasmids and resistance islands related to different insertion sequence (IS) elements, which were located in both the chromosome and in plasmids, which conferred resistance to multiple antimicrobials, including carbapenems. Carbapenem resistance might be caused by a Tn2008 carrying the bla_OXA–23 gene. Some plasmids were shared between the isolates. Larger plasmids were less conserved than smaller ones and they shared some homologous regions, while others were more diverse, suggesting that these big plasmids are more plastic than the smaller ones. The genetic basis of antimicrobial resistance in Bolivia has not been deeply studied until now, and the mobilome of these A. baumannii isolates, combined with their multi-drug resistant phenotype, mirror the transfer and prevalence of MGEs contributing to the spread of antibiotic resistance worldwide and require special attention. These findings could be useful to understand the antimicrobial resistance genetics of A. baumannii in Bolivia and the difficulty in tackling these infections.

[Elderly patients with an abdominal aortic aneurysm; preoperative frailty-screening and a multidisciplinary approach]

Aneurysm of the abdominal aorta is common and can be treated with endovascular repair, open surgical repair or conservative treatment. Risk-stratification and treatment decision-making can be complex in frail patients and depends largely on anatomy, life-expectancy and functional capacity. Currently, risk-stratification in the Netherlands is primarily based on comorbidities and age. Insight in a patient's resilience could provide important additional information. For this reason, St. Antonius hospital has implemented an Anaesthesia Geriatric Evaluation (AGE) to screen for frailty in high risk vascular surgery patients. Results of frailty-screening are discussed in a multi-disciplinary team (MDT) to assess perioperative risk and compose a personal treatment plan. This paper presents a case-series of three patients to illustrate the additional value of MDT care and frailty-screening in a high-risk vascular surgery population.

Editor's Choice - Nationwide Analysis of Patients Undergoing Iliac Artery Aneurysm Repair in the Netherlands

OBJECTIVE

The new 2019 guideline of the European Society for Vascular Surgery (ESVS) recommends consideration for elective iliac artery aneurysm (eIAA) repair when the iliac diameter exceeds 3.5 cm, as opposed to 3.0 cm previously. The current study assessed diameters at time of eIAA repair and ruptured IAA (rIAA) repair and compared clinical outcomes after open surgical repair (OSR) and endovascular aneurysm repair (EVAR).

METHODS

This retrospective observational study used the nationwide Dutch Surgical Aneurysm Audit (DSAA) registry that includes all patients who undergo aorto-iliac aneurysm repair in the Netherlands. All patients who underwent primary IAA repair between 1 January 2014 and 1 January 2018 were included. Diameters at time of eIAA and rIAA repair were compared in a descriptive fashion. The anatomical location of the IAA was not registered in the registry. Patient characteristics and outcomes of OSR and EVAR were compared with appropriate statistical tests.

RESULTS

The DSAA registry comprised 974 patients who underwent IAA repair. A total of 851 patients were included after exclusion of patients undergoing revision surgery and patients with missing essential variables. eIAA repair was carried out in 713 patients, rIAA repair in 102, and symptomatic IAA repair in 36. OSR was performed in 205, EVAR in 618, and hybrid repairs and conversions in 28. The median maximum IAA diameter at the time of eIAA and rIAA repair was 43 (IQR 38-50) mm and 68 (IQR 58-85) mm, respectively. Mortality was 1.3% (95% CI 0.7-2.4) after eIAA repair and 25.5% (95% CI 18.0-34.7) after rIAA repair. Mortality was not significantly different between the OSR and EVAR subgroups. Elective OSR was associated with significantly more complications than EVAR (intra-operative: 9.8% vs. 3.6%, post-operative: 34.0% vs. 13.8%, respectively).

CONCLUSION

In the Netherlands, most eIAA repairs are performed at diameters larger than recommended by the ESVS guideline. These findings appear to support the recent increase in the threshold diameter for eIAA repair.

Klebsiella variicola causing nosocomial transmission among neonates - an emerging pathogen?

Introduction. Transmission of Enterobacterales in neonatal intensive care units (NICU) can cause outbreaks of colonization and invasive infections among neonates. Two clusters of nosocomial transmission of Klebsiella pneumoniae identified by MALDI-ToF mass-spectrometry were suspected at two NICUs in July and August 2016.Aim. To assess the potential transmission of K. pneumoniae among neonates.Methodology. Whole-genome sequencing (WGS) was performed of K. pneumoniae isolates obtained through targeted surveillance of patients and environmental sampling.Results. WGS data revealed that patient and environmental isolates represented two species, K. pneumoniae and K. variicola. Core-genome multi-locus sequence typing (cgMLST) of the isolates identified three separate transmission clusters, in Hospital A a cluster of K. pneumoniae isolates in 12 children and two environmental samples and a second cluster of K. variicola isolates in five children. In Hospital B a cluster of K. pneumoniae isolates from three children and five unrelated isolates of K. pneumoniae and two unrelated isolates of K. variicola were found.Conclusion. K. variicola can cause hospital outbreaks of colonization and infection similar to other Klebsiella spp.Preliminary results from this study were presented at the 27th European Congress of Clinical Microbiology and Infectious Diseases, April 22-25, 2018, Vienna, Austria.

Diversity of amino acid substitutions in PmrCAB associated with colistin resistance in clinical isolates of Acinetobacter baumannii

This study aimed to investigate the mechanisms of colistin resistance in 64 Acinetobacter baumannii isolates obtained from patients with ventilator-associated pneumonia hospitalised in Greece, Italy and Spain. In total, 31 A. baumannii isolates were colistin-resistant. Several novel amino acid substitutions in PmrCAB were found in 27 colistin-resistant A. baumannii. Most substitutions were detected in PmrB, indicating the importance of the histidine kinase for colistin resistance. In two colistin-resistant isolates, 93 amino acid changes were observed in PmrCAB compared with A. baumannii ACICU, and homologous recombination across different clonal lineages was suggested. Analysis of gene expression revealed increased pmrC expression in isolates harbouring pmrCAB mutations. Complementation of A. baumannii ATCC 19606 and ATCC 17978 with a pmrAB variant revealed increased pmrC expression but unchanged colistin MICs, indicating additional unknown factors associated with colistin resistance. Moreover, a combination of PmrB and PmrC alterations was associated with very high colistin MICs, suggesting accumulation of mutations as the mechanism for high-level resistance. The pmrC homologue eptA was detected in 29 colistin-susceptible and 26 colistin-resistant isolates. ISAba1 was found upstream of eptA in eight colistin-susceptible and one colistin-resistant isolate and eptA was disrupted by ISAba125 in two colistin-resistant isolates. Whilst in most isolates an association of eptA with colistin resistance was excluded, in one isolate an amino acid substitution in EptA (R127L) combined with a point mutation in ISAba1 upstream of eptA contributed to elevated colistin MICs. This study helps to gain an insight into the diversity and complexity of colistin resistance in A. baumannii.

Laser-induced vapor nanobubbles improve diffusion in biofilms of antimicrobial agents for wound care

Being responsible for delayed wound healing, the presence of biofilms in infected wounds leads to chronic, and difficult to treat infections. One of the reasons why antimicrobial treatment often fails to cure biofilm infections is the reduced penetration rate of antibiotics through dense biofilms. Strategies that have the ability to somehow interfere with the integrity of biofilms and allowing a better penetration of drugs are highly sought after. A promising new approach is the use of laser-induced vapor nanobubbles (VNB), of which it was recently demonstrated that it can substantially enhance the penetration of antibiotics into biofilms, resulting in a marked improvement of the killing efficiency. In this study, we examined if treatment of biofilms with laser-induced vapor nanobubbles (VNB) can enhance the potency of antimicrobials which are commonly used to treat wound infections, including povidone-iodine, chlorhexidine, benzalkonium chloride, cetrimonium bromide and mupirocin. Our investigations were performed on Pseudomonas aeruginosa and Staphylococcus aureus biofilms, which are often implicated in chronic wound infections. Pre-treatment of biofilms with laser-induced VNB did enhance the killing efficiency of those antimicrobials which experience a diffusion barrier in the biofilms, while this was not the case for those compounds for which there is no diffusion barrier. The magnitude of the enhanced potency was in most cases similar to the enhancement that was obtained when the biofilms were completely disrupted by vortexing and sonication. These results show that laser-induced VNB are indeed a very efficient way to enhance drug penetration deep into biofilms, and pave the way towards clinical translation of this novel approach for treatment of wound infections.

Genetic Features of Antarctic Acinetobacter radioresistens Strain A154 Harboring Multiple Antibiotic-Resistance Genes

While antibiotic-resistant bacteria have been detected in extreme environments, including Antarctica, to date there are no reports of Acinetobacter species isolated from this region. Here, we characterized by whole-genome sequencing (WGS) the genetic content of a single antibiotic-resistant Acinetobacter spp. isolate (A154) collected in Antarctica. The isolate was recovered in 2013 from soil samples at Fildes Peninsula, Antarctica, and was identified by detection of the intrinsic OXA-23 gene, and confirmed by Tetra Correlation Search (TCS) and WGS. The antibiotic susceptibility profile was determined by disc diffusion, E-test, and broth microdilution methods. From WGS data, the acquired resistome and insertion sequence (IS) content were identified by in silico analyses. Plasmids were studied by the alkaline lysis method followed by pulsed-field gel electrophoresis and conventional PCR. The A154 isolate was identified as A. radioresistens by WGS analysis and displayed >99.9 of similarity by TCS in relation with the databases. Moreover, it was resistant to ampicillin, ceftriaxone, ceftazidime, cefepime, cefotaxime, streptomycin, and kanamycin. Likewise, in addition to the intrinsic bla_{OXA−23−like} gene, A154 harbored the plasmid-encoded antibiotic-resistance genes bla_PER−2, tet(B), aph(3′)-Vla, strA, and strB, as well as a large diversity of ISs. This is the first report of antibiotic-resistant A. radioresistens in Antarctica. Our findings show the presence of several resistance genes which could be either intrinsic or acquired in the region.

In vitro activity of mecillinam and nitroxoline against Neisseria gonorrhoeae - re-purposing old antibiotics in the multi-drug resistance era

In 2018, the European Centre for Disease Prevention and Control reported the first cases of extensively drug-resistant Neisseria gonorrhoeae infections in Europe. Seeking new options for antimicrobial therapy we investigated the susceptibility of N. gonorrhoeae to nitroxoline (NIT) and mecillinam (MCM), both of which are currently only indicated to treat uncomplicated urinary tract infections. Clinical N. gonorrhoeae isolates with non-susceptibility to penicillin from two German medical centres were included (n =27). Most isolates were also non-susceptible to a range of other anti-gonococcal antimicrobials (cefotaxime, ciprofloxacin, azithromycin, tetracycline). All isolates were further characterized by multi-locus sequence typing. MICs of penicillin and cefotaxime were determined by agar gradient diffusion. Production of penicillinase was tested by cefinase disk test. Susceptibility of MCM was investigated by agar dilution, NIT by agar dilution and disk diffusion. Penicillin MICs ranged from 0.125 to 64 mg l^-1 and MICs of cefotaxime ranged from < 0.016 to 1 mg l^-1 . Five isolates were penicillinase-producers. MICs of MCM ranged from 16 to > 128 mg l^-1 whereas MICs of NIT ranged from 0.125 to 2 mg l^-1 . NIT disk diffusion (median zone diameter 32 mm) correlated well with results from agar dilution. We demonstrated excellent in vitro activity of NIT against clinical N. gonorrhoeae isolates with non-susceptibility to standard anti-gonococcal antibiotics. MCM activity was unsatisfactory. Correlation of agar dilution and disk diffusion in NIT susceptibility testing is an important aspect with potential clinical implications.

Correction to: Percutaneous Deep Venous Arterialization for Severe Critical Limb Ischemia in Patients With No Option of Revascularization: Early Experience From Two European Centers

The fifth author's name was incorrectly published as "M. Messas". The correct name is "E. Messas". The original article has been corrected.

Applicability of generic quality indicators for appropriate antibiotic use in daily hospital practice: a cross-sectional point-prevalence multicenter study

The ability to monitor the appropriateness of hospital antibiotic use is a key element of an effective antibiotic stewardship program. A set of 11 generic quality indicators (QIs) was previously developed to assess the quality of antibiotic use in hospitalized adults treated for a bacterial infection. The primary aim of the current study was to assess the clinimetric properties of these QIs (nine process and two structure indicators) in daily clinical practice. In a cross-sectional point-prevalence survey, performed in 2011 and 2012, 1890 inpatients from 22 hospitals in the Netherlands treated with antibiotics for a suspected bacterial infection were included, and data were extracted from medical records. In this cohort we tested the measurability, applicability, reliability, room for improvement and case mix stability of the previously developed QIs. Low applicability (≤10% of reviewed patients) was found for the QIs 'therapeutic drug monitoring', 'adapting antibiotics to renal function' and 'discontinue empirical therapy in case of lack of clinical and/or microbiological evidence of infection'. For the latter, we also found a low inter-observer agreement (kappa <0.4). One QI showed low improvement potential. The remaining seven QIs had sound clinimetric properties. Case-mix correction was necessary for most process QIs. For all QIs, we found ample room for improvement and large variation between hospitals. Establishing the clinimetric properties was essential, as four of the 11 previously selected QIs showed unsatisfactory properties in this practice test. Since the quality of antibiotic use and the process of documenting data is changing over time and may vary per country, QIs should always be tested in practice first.

An undetected common renal arterial trunk: surgical consequences and morbidity analysis

We present a patient with a recurrent precaval left renal artery, stemming from a right-sided common trunk renal artery. The patient was a 44-year male who presented with a post-traumatic grade IV renal injury. After 3 months without renal function improvement and repeated urinary tract infection, a laparoscopic nephrectomy of the affected right kidney was performed, without upfront identification of the vascular variation, resulting in ischemia of the remaining left kidney. An anastomosis of the common renal trunk and the distal left renal artery was created in between the abdominal aorta and the inferior vena cava. This case describes the importance of upfront detection of renal vascular variations using the appropriate imaging techniques.

COMADRE: a global data base of animal demography

The open‐data scientific philosophy is being widely adopted and proving to promote considerable progress in ecology and evolution. Open‐data global data bases now exist on animal migration, species distribution, conservation status, etc. However, a gap exists for data on population dynamics spanning the rich diversity of the animal kingdom world‐wide. This information is fundamental to our understanding of the conditions that have shaped variation in animal life histories and their relationships with the environment, as well as the determinants of invasion and extinction.

Matrix population models (MPMs) are among the most widely used demographic tools by animal ecologists. MPMs project population dynamics based on the reproduction, survival and development of individuals in a population over their life cycle. The outputs from MPMs have direct biological interpretations, facilitating comparisons among animal species as different as Caenorhabditis elegans, Loxodonta africana and Homo sapiens.

Thousands of animal demographic records exist in the form of MPMs, but they are dispersed throughout the literature, rendering comparative analyses difficult. Here, we introduce the COMADRE Animal Matrix Database, an open‐data online repository, which in its version 1.0.0 contains data on 345 species world‐wide, from 402 studies with a total of 1625 population projection matrices. COMADRE also contains ancillary information (e.g. ecoregion, taxonomy, biogeography, etc.) that facilitates interpretation of the numerous demographic metrics that can be derived from its MPMs. We provide R code to some of these examples.

Synthesis: We introduce the COMADRE Animal Matrix Database, a resource for animal demography. Its open‐data nature, together with its ancillary information, will facilitate comparative analysis, as will the growing availability of databases focusing on other aspects of the rich animal diversity, and tools to query and combine them. Through future frequent updates of COMADRE, and its integration with other online resources, we encourage animal ecologists to tackle global ecological and evolutionary questions with unprecedented sample size.

Results of reinterventions for failed endovascular aortic repair: a single-center experience

AIM

The aim of this paper was to review technical success and clinical outcome of reinterventions to treat complications after endovascular abdominal aortic aneurysm (AAA) repair (EVAR) in a tertiary vascular center.

METHODS

The study enrolled 107 patients treated for post-EVAR complications between January 2005 and March 2014. Details of reinterventions, technical success, and midterm clinical outcome were analyzed for reinterventions. Radiologic follow-up after reinterventions was performed by computed tomography scans and duplex ultrasonography.

RESULTS

Indications for reinterventions in the 107 patients were predominantly endoleaks type Ia, Ib, II, and III (55.1%). Endograft obstructions were observed in 39 patients (36.4%). The initial technical success rate for the 107 reinterventions was 93.5% (N.=100). Median follow-up postreintervention was 20 months (range, 1-107 months). During follow-up, 34 of 107 patients (31.8%) needed at least one renewed reintervention. Kaplan-Meier analysis of overall survival after the primary reinterventions was 85% at 1 year, and 78% at 3 years of follow-up. AAA/EVAR-associated mortality was 4% at 3 years. Kaplan-Meier survival estimation of freedom of recurrence was 88% at 1 year post-reintervention and 78% at 3 years. Renewed reintervention-free survival dropped to 78% at 1 year and 58% at 3 years.

CONCLUSION

In this series of patients, the technical success rate of reinterventions to treat post-EVAR complications was high. During a median follow-up of 20 months, AAA-associated mortality is low, but the need for renewed (endovascular) reinterventions is substantial.

Quality-of-life in patients with post-traumatic hypopituitarism

PRIMARY OBJECTIVE

Hypopituitarism is a frequent complication in patients after traumatic brain injury (TBI). Both TBI and hypopituitarism can lead to complex cognitive and affective deficits. This study was intended to examine the quality-of-life in patients with post-traumatic hypopituitarism (PTH) and to discern the effect of this endocrinological disorder on general outcome of patients after TBI including earning capacity. Research type: Retrospective analysis of clinical data.

METHODS AND PROCEDURES

Ninety-seven symptomatic patients were screened after TBI for PTH. Their results were examined in the SF-36 [a standardized questionnaire for quality of life (QoL)] comparing the groups with or without PTH. After 6 months of hormone substitution (if necessary), patients were asked to repeat the SF-36.

MAIN OUTCOMES AND RESULTS

Forty-six patients were diagnosed with PTH (47.5%). All patients included had a significantly lower QoL compared to the standard population. QoL was significantly worse in patients with PTH. There was no significant difference with regard to earning capacity. After hormone substitution, patients achieved better SF-36-results, albeit the difference was lacking statistical significance.

CONCLUSIONS

PTH is frequent after TBI. PTH turns out to further diminish QoL, without affecting earning capacity. Hormone substitution might improve QoL in patients with PTH, but future research is needed to confirm this hypothesis.

CT angiography to evaluate hemodynamic changes in popliteal artery aneurysms during flexion and extension of the knee joint

AIM

The aim of this study was to find out which characteristics of an asymptomatic popliteal artery aneurysm (PAA) will increase the risk for acute thrombosis.

METHODS

This was a single-center prospective study of consecutive patients with asymptomatic PAAs presenting from January 2010 to April 2012. Computed tomography angiography was used to perform measurements of the PAA during 0º extension and 90º flexion of the knee. After semi-automated segmentation of the popliteal artery (PA) lumen, a center lumen line (CLL) was automatically constructed.

RESULTS

The study included 16 asymptomatic PAAs. Median lumen area of the PA was directly proximal and distal of the PAA 57 mm2 (IQR, 44-87 mm2) and 46 mm2 (IQR, 32-66 mm2) in extension vs. 51 mm2 (IQR, 38-73 mm2) and 38 mm2 (IQR, 30-62 mm2) during 90º flexion, respectively (P=0.007) and (P=0.03). The median of the greatest decrease in lumen area after flexion and extension of the knee was 36 mm (IQR, 28-48 mm) in PAAs≥30 mm compared with 11 mm (IQR, 4-18 mm) in PAAs<30 mm (P<0.05). The proximal angulation was a median 48° in extension (IQR, 27-61º) and 75° during flexion (IQR, 46-99º; P=0.02). Distal angulation was a median of 31° (IQR, 21-42º) after extension vs. 62° (IQR, 33-81º) during flexion (P=0.03).

CONCLUSION

Knee bending in patients with PAAs will lead to a reduction in the lumen area of the PAA and a change in the degree of angulation of the PAA. A significant decrease in lumen area was seen in PAAs≥30 mm compared with PAAs<30 mm after flexion of the knee.

Appropriateness of antimicrobial therapy: a multicentre prevalence survey in the Netherlands, 2008-2009

A survey was carried out to determine the prevalence and appropriateness of antimicrobial therapy (AMT) in the Netherlands and to identify determinants for inappropriate AMT. Prevalence surveys of patients hospitalised in the Netherlands were performed three times in 2008 and 2009. Patients' demographic, infection-related and AMT-related data were collected from hospital wards. A total of 19 hospitals participated, consisting of a mix of university, teaching and general hospitals, which were distributed evenly across the country. The appropriateness of AMT was assessed using a standardised algorithm based on local AMT prescription guidelines. A total of 7,853 patients were included, of which 2,327 (29.6%) patients were on AMT (range: 20.8–39.5%). In 372 patients (16% of patients on AMT), treatment was considered inappropriate. In 265 (11.4%) patients on AMT, appropriateness of treatment was not judged because of insufficient information. The percentage of patients without a judgment varied considerably between the participating hospitals (range: 1.3–36.2%). Appropriate AMT use was significantly associated with a patient being in an intensive care unit, having a central venous catheter and being given beta-lactamase-sensitive penicillins. The use of fluoroquinolones was significantly associated with more frequent inappropriate use. There was considerable and significant variation between the participating hospitals in the amount of antimicrobials prescribed and the appropriateness of their use. To improve the completeness and reliability of such surveys, there is a need for intensive training of observers and medical staff in recording information.

Vitex agnus castus as prophylaxis for osteopenia after orchidectomy in rats compared with estradiol and testosterone supplementation

Osteoporosis research undertaken in males is rare and there are only a few therapeutic options. Phytoestrogens might be a safe alternative for prophylaxis. Sixty 3-month-old male rats were orchidectomized and divided into five groups. The groups either received soy-free food (C), estradiol (E), testosterone (T) or Vitex agnus castus in different concentrations (AC high/AC low) for 12 weeks. The tibia metaphysis was tested biomechanically and histomorphometrically. The AC high group reached 87% of the biomechanical values of the estradiol group and was significantly superior to the control group. Testosterone supplementation resulted in poor biomechanical properties. The cortical bone parameters of the AC group were similar to the control group, while supplementation with estradiol and testosterone demonstrated a reduction of cortical bone. The AC high group reached 88.4% of trabecular bone area, 80.7% of trabecular number and 66.9% of the number of trabecular nodes compared with estradiol supplementation. Vitex agnus castus demonstrated osteoprotective effects in males. It preserves the cortical as well as the trabecular bone and might be a safe alternative for HRT. Testosterone supplementation has positive effects on trabecular bone, which are concurrently counteracted by the loss of cortical bone.

[Diagnostic image (381). A man with painful, red spots on one foot]

A 49-year-old Turkish man with classic Kaposi sarcoma on his right foot, was successfully treated by irradiation.

[Diagnostic image (378). A woman with a subungual pigmentation of the left hallux]

An 81-year-old woman presented with a subungual pigmented lesion of the left hallux, caused by a malignant acral-lentiginous melanoma.

[Acute compartment syndrome of the foot]

In two patients, a girl aged 2 and a man aged 52 years, who had suffered a severe crush trauma, acute compartment syndrome of the foot was diagnosed. Decompression by means of one medial and two dorsal dermato-fasciotomy incisions was carried out and fractures of the metatarsals were repaired using K-wires. The girl recovered completely, but the man developed progressive necrosis in the flexors of the foot and on the skin on the foot sole which necessitated amputation of the foot. Acute compartment syndrome of the foot is an uncommon disease and is mainly characterised by extreme pain and often diffuse swelling of the foot. It is a serious threat to the foot which can lead to severe long-term complications including contractures, deformity and paralysis. Compartment syndrome of the foot is a primary clinical diagnosis. When in doubt, direct pressure measurement of the foot compartments should be done by means of needle catheterisation. If compartment pressure exceeds 30 mm Hg, acute dermato-fasciotomy of all nine compartments is indicated. A combined medial and dorsal approach is adopted to release the foot compartments; three incisions are usually sufficient. If fractures are present, these are repaired at the same time. Within four hours an unnoticed compartment syndrome can lead to irreversible ischaemia of the nerves and muscle tissue with long-term irreversible consequences.

Ergebnisqualität bei der Maschinellen Autotransfusion und Einflussfaktoren

Also intraoperative blood salvage (IBS) requires a system for quality management with controls of product an process quality. These can help early detection of malfunctions. For proper reaction and for improvement of quality a deep understanding of the process of blood salvage is necessary. This is supported by experimental testing of equipment, programs, and process variables, and by analysis of their effects on the process. The use of fresh whole blood and total protein as wash-out parameter in these tests is superior to outdated banked RBC and free haemoglobin. The process of aspiration turns out much less harmful than expected, when tested with fresh blood. Low wash volumes, fast washing rates, and half full bowls should be avoided. Plasma wash-out is improved by slower washing or by higher wash volumes, but the latter decrease RBC recovery. Such quality management helps to provide blood of excellent quality by IBS for optimal haemotherapy.

Natural carbon isotopes used to study methane consumption and production in soil

Changes in the isotopic composition of carbon can be used to reveal simultaneous occurrence of methane production and oxidation in soil. The method is conducted in laboratory jar experiments as well as in the field by using flux chambers. Simultaneous occurrence of production and oxidation of methane was suggested.

Specificity of endothelial cell reorientation in response to cyclic mechanical stretching

Evidence suggests that cellular responses to mechanical stimuli depend specifically on the type of stimuli imposed. For example, when subjected to fluid shear stress, endothelial cells align along the flow direction. In contrast, in response to cyclic stretching, cells align away from the stretching direction. However, a few aspects of this cell alignment response remain to be clarified: (1) Is the cell alignment due to actual cell reorientation or selective cell detachment? (2) Does the resulting cell alignment represent a response of the cells to elongation or shortening, or both? (3) Does the cell alignment depend on the stretching magnitude or rate, or both? Finally, the role of the actin cytoskeleton and microtubules in the cell alignment response remains unclear. To address these questions, we grew human aortic endothelial cells on deformable silicone membranes and subjected them to three types of cyclic stretching: simple elongation, pure uniaxial stretching and equi-biaxial stretching. Examination of the same cells before and after stretching revealed that they reoriented. Cells subjected to either simple elongation or pure uniaxial stretching reoriented specifically toward the direction of minimal substrate deformation, even though the directions for the two types of stretching differed by only about 20 degrees. At comparable stretching durations, the extent of cell reorientation was more closely related to the stretching magnitude than the stretching rate. The actin cytoskeleton of the endothelial cell subjected to either type of stretching was reorganized into parallel arrays of actin filaments (i.e., stress fibers) aligned in the direction of the minimal substrate deformation. Furthermore, in response to equi-biaxial stretching, the actin cytoskeleton was remodeled into a "tent-like" structure oriented out of the membrane plane-again towards the direction of the minimal substrate deformation. Finally, abolishing microtubules prevented neither the formation of stress fibers nor cell reorientation. Thus, endothelial cells respond very specifically to the type of deformation imposed upon them.