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Bloodstream infections (BSI) are a frequent complication in patients with hematological and oncological diseases. However, the impact of different bacterial species causing BSI and of multiple BSI remains incompletely understood. We performed a retrospective study profiling 637 bacterial BSI episodes in hematological and oncological patients. Based on the 30-day (30d) overall survival (OS), we analyzed different types of multiple BSI and grouped BSI-associated bacteria into clusters followed by further assessment of clinical and infection-related characteristics. We discovered that polymicrobial BSI (different organisms on the first day of a BSI episode) and sequential BSI (another BSI before the respective BSI episode) were associated with a worse 30d OS. Different bacterial groups could be classified into three BSI outcome clusters based on 30d OS: favorable (FAV) including mainly common skin contaminants, Escherichia spp. and Streptococcus spp.; intermediate (INT) including mainly Enterococcus spp., vancomycin-resistant Enterococcus spp., and multidrug-resistant gram-negative bacteria (MDRGN); and adverse (ADV) including MDRGN with an additional carbapenem-resistance (MDRGN+CR). A polymicrobial or sequential BSI especially influenced the outcome in the combination of two INT cluster BSI. The presence of a polymicrobial BSI and the assignment into the BSI outcome clusters were identified as independent risk factors for 30d mortality in a Cox multivariate regression analysis. The assignment to a BSI outcome cluster and the differentiated perspective of multiple BSI open new insights into the prognosis of patients with BSI and should be further validated in other patient cohorts.
Objective: This study aims to evaluate catheter management in acute epididymitis (AE) patients requiring inpatient treatment and risk factors predicting severity of disease.
Material and Methods: Patients with diagnosed AE and inpatient treatment between 2004 and 2019 at the University Hospital Frankfurt were analyzed. A risk score, rating severity of AE, including residual urine > 100 ml, fever > 38.0°C, C-reactive protein (CRP) > 5 mg/dl, and white blood count (WBC) > 10/nl was introduced.
Results: Of 334 patients, 107 (32%) received a catheter (transurethral (TC): n = 53, 16%, suprapubic (SPC): n = 54, 16%). Catheter patients were older, exhibited more comorbidities, and had higher CRP and WBC compared with the non-catheter group (NC). Median length of stay (LOS) was longer in the catheter group (7 vs. 6 days, p < 0.001), whereas necessity of abscess surgery and recurrent epididymitis did not differ. No differences in those parameters were recorded between TC and SPC. According to our established risk score, 147 (44%) patients exhibited 0–1 (low-risk) and 187 (56%) 2–4 risk factors (high-risk). In the high-risk group, patients received a catheter significantly more often than with low-risk (TC: 22 vs. 9%; SPC: 19 vs. 12%, both p ≤ 0.01). Catheter or high-risk patients exhibited positive urine cultures more frequently than NC or low-risk patients. LOS was comparable between high-risk patients with catheter and low-risk NC patients.
Conclusion: Patients with AE who received a catheter at admission were older, multimorbid, and exhibited more severe symptoms of disease compared with the NC patients. A protective effect of catheters might be attributable to patients with adverse risk constellations or high burden of comorbidities. The introduced risk score indicates a possibility for risk stratification.
Intestinal carriage of multidrug-resistant bacteria among healthcare professionals in Germany
(2017)
Healthcare professionals (HCP) might be at increased risk of acquisition of multidrug-resistant bacteria (MDRB), i.e., methillicin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and multidrug-resistant gram-negative bacteria (MDRGN) and could be an unidentified source of MDRB transmission.
The aim of this study was to determine the prevalence as well as risk factors of MDRB colonization among HCP.
HCP (n=107) taking part in an antibiotic stewardship program, were voluntarily recruited to perform a rectal swab and to fill in a questionnaire to identify risk factors of MDRB carriage, i.e. being physician, gender, travel abroad within the previous 12 months, vegetarianism, regular consumption of raw meat, contact to domestic animals, household members with contact to livestock, work or fellowship abroad, as well as medical treatment abroad and antibiotic therapy within the previous 12 months.
Selective solid media were used to determine the colonization rate with MRSA, VRE and MDRGN. MDRGN were further characterized by molecular analysis of underlying β-lactamases.
None of the participants had an intestinal colonization with MRSA or VRE. 3.7% of the participants were colonized with extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, predominantly blaCTX-M type. Neither additional flouroquinolone resistance nor carbapenem resistance was detected in any of these isolates. No risk factors were identified to have a significant impact of MDRB carriage among HCP.
A colonization rate of 3.7% with ESBL-producing Enterobacteriaceae is of interest, but comparing it to previously published data with similar colonization rates in the healthy population in the same geographic area, it is probably less an occupational risk.
Introduction: There is still an ongoing debate whether a transrectal ultrasound (TRUS) approach for prostate biopsies is associated with higher (infectious) complications rates compared to transperineal biopsies. This is especially of great interests in settings with elevated frequencies of multidrug resistant organisms (MDRO).
Materials and Methods: Between 01/2018 and 05/2019 230 patients underwent a TRUS-guided prostate biopsy at the department of Urology at University Hospital Frankfurt. Patients were followed up within the clinical routine that was not conducted earlier than 6 weeks after the biopsy. Among 230 biopsies, 180 patients took part in the follow-up. No patients were excluded. Patients were analyzed retrospectively regarding complications, infections and underlying infectious agents or needed interventions.
Results: Of all patients with follow up, 84 patients underwent a systematic biopsy (SB) and 96 a targeted biopsy (TB) after MRI of the prostate with additional SB. 74.8% of the patients were biopsy-naïve. The most frequent objective complications (classified by Clavien-Dindo) lasting longer than one day after biopsy were hematuria (17.9%, n = 32), hematospermia (13.9%, n = 25), rectal bleeding (2.8%, n = 5), and pain (2.2%, n = 4). Besides a known high MDRO prevalence in the Rhine-Main region, only one patient (0.6%) developed fever after biopsy. One patient each (0.6%) consulted a physician due to urinary retention, rectal bleeding or gross hematuria. There were no significant differences in complications seen between SB and SB + TB patients. The rate of patients who consulted a physician was significantly higher for patients with one or more prior biopsies compared to biopsy-naïve patients.
Conclusion: Complications after transrectal prostate biopsies are rare and often self-limiting. Infections were seen in <1% of all patients, regardless of an elevated local prevalence of MDROs. Severe complications (Clavien-Dindo ≥ IIIa) were only seen in 3 (1.7%) of the patients. Repeated biopsy is associated with higher complication rates in general.
Background: Multidrug-resistant Gram-negative bacteria (MRGN) and the infections they cause are a serious threat and a challenge to the healthcare system. This particularly applies to carbapenem-resistant Gram-negative bacteria (CRGN). Currently, the introduction of a nationwide mandatory notification system for CRGN in Germany is under consideration. Against this background, this paper presents an analysis of the mandatory reporting system for CRGN in effect since November 2011 in the federal state of Hesse (Germany).
Materials and methods: All carbapenem-resistant Gram-negative bacteria and the detected carbapenemases reported to the public health department of the city of Frankfurt am Main, Hesse, Germany, on the basis of the mandatory notification system were analyzed.
Results: 827 CRGN cases were reported to the public health department of Frankfurt/Main between April 2012 and December 2015. The following bacterial species were reported: Pseudomonas spp. (n=268), Acinetobacter spp. (n=183), Klebsiella spp. (n=195), Enterobacter spp. (n=77), Escherichia coli (n=75) and others (n=29). Between 2012 and 2015, a reduction of the CRGN reports was noticed, mainly due to changes in the reporting of Pseudomonas spp. Between 2012 and 2015, the total number of notifications decreased slightly, although the number of reported CRGN in screening samples increased, thus giving no indication of a decreased testing frequency. For 10.5% of the patients, the place of residence was not Germany, 18.0% of the patients had previously stayed in hospitals abroad, often in countries with a high CRGN prevalence. CRGN bacteria were reported from all of Frankfurt’s hospitals, and 3.9% were reported from out-patient care facilities. Carbapenemases were detected and reported in 251 CRGN bacteria, including 73 OXA-48, 76 OXA-23, 56 NDM subtypes, and 21 KPC subtypes. There have been no major epidemiological signs of outbreak scenarios.
Discussion: CRGN bacteria are already widespread in patients from hospitals and out-patient care facilities. Clearly, infection control measurements should therefore not only include hospital patients but also those receiving out-patient care. Screening strategies focused on patients from foreign countries with high MRGN prevalence is not sufficient, as only 10.5% of MRGN patients resided in those countries, and only 18% of the patients had been previously treated in a foreign hospital. In a public health context, infection control measures should therefore encompass broader screening strategies.
Multidrug-resistant Gram-negative bacteria (MDR GNB) were found to colonise 60.8% (95% confidence interval: 52.3–68.9) of 143 refugee patients mainly from Syria (47), Afghanistan (29), and Somalia (14) admitted to the University Hospital Frankfurt, Germany, between June and December 2015. This percentage exceeds the prevalence of MDR GNB in resident patients four–fold. Healthcare personnel should be aware of this and the need to implement or adapt adequate infection control measures.
Tolerizing CTL by sustained hepatic PD-L1 expression provides a new therapy spproach in mouse sepsis
(2019)
Cytotoxic T lymphocyte (CTL) activation contributes to liver damage during sepsis, but the mechanisms involved are largely unknown. Understanding the underlying principle will permit interference with CTL activation and thus, provide a new therapeutic option.
Methods: To elucidate the mechanism leading to CTL activation we used the Hepa1-6 cell line in vitro and the mouse model of in vivo polymicrobial sepsis, following cecal-ligation and -puncture (CLP) in wildtype, myeloid specific NOX-2, global NOX2 and NOX4 knockout mice, and their survival as a final readout. In this in vivo setting, we also determined hepatic mRNA and protein expression as well as clinical parameters of liver damage - aspartate- and alanine amino-transaminases. Hepatocyte specific overexpression of PD-L1 was achieved in vivo by adenoviral infection and transposon-based gene transfer using hydrodynamic injection.
Results: We observed downregulation of PD-L1 on hepatocytes in the murine sepsis model. Adenoviral and transposon-based gene transfer to restore PD-L1 expression, significantly improved survival and reduced the release of liver damage, as PD-L1 is a co-receptor that negatively regulates T cell function. Similar protection was observed during pharmacological intervention using recombinant PD-L1-Fc. N-acetylcysteine blocked the downregulation of PD-L1 suggesting the involvement of reactive oxygen species. This was confirmed in vivo, as we observed significant upregulation of PD-L1 expression in NOX4 knockout mice, following sham operation, whereas its expression in global as well as myeloid lineage NOX2 knockout mice was comparable to that in the wild type animals. PD-L1 expression remained high following CLP only in total NOX2 knockouts, resulting in significantly reduced release of liver damage markers.
Conclusion: These results suggest that, contrary to common assumption, maintaining PD-L1 expression on hepatocytes improves liver damage and survival of mice during sepsis. We conclude that administering recombinant PD-L1 or inhibiting NOX2 activity might offer a new therapeutic option in sepsis.
Acinetobacter baumannii is a Gram-negative pathogen that causes a multitude of nosocomial infections. The Acinetobacter trimeric autotransporter adhesin (Ata) belongs to the superfamily of trimeric autotransporter adhesins which are important virulence factors in many Gram-negative species. Phylogenetic profiling revealed that ata is present in 78% of all sequenced A. baumannii isolates but only in 2% of the closely related species A. calcoaceticus and A. pittii. Employing a markerless ata deletion mutant of A. baumannii ATCC 19606 we show that adhesion to and invasion into human endothelial and epithelial cells depend on Ata. Infection of primary human umbilical cord vein endothelial cells (HUVECs) with A. baumannii led to the secretion of interleukin (IL)-6 and IL-8 in a time- and Ata-dependent manner. Furthermore, infection of HUVECs by WT A. baumannii was associated with higher rates of apoptosis via activation of caspases-3 and caspase-7, but not necrosis, in comparison to ∆ata. Ata deletion mutants were furthermore attenuated in their ability to kill larvae of Galleria mellonella and to survive in larvae when injected at sublethal doses. This indicates that Ata is an important multifunctional virulence factor in A. baumannii that mediates adhesion and invasion, induces apoptosis and contributes to pathogenicity in vivo.
Introduction: The global spread of multidrug-resistant organisms (MDRO) complicates treatment and isolation measures in hospitals and has shown to increase mortality. Patients with disease- or therapy-related immunodeficiency are especially at risk for fatal infections caused by MDRO. The impact of MDRO colonization on the clinical course of AML patients undergoing intensive induction chemotherapy—a potentially curative but highly toxic treatment option—has not been systematically studied.
Materials & methods: 312 AML patients undergoing intensive induction chemotherapy between 2007 and 2015 were examined for MDRO colonization. Patients with evidence for MDRO before or during the hospital stay of induction chemotherapy were defined as colonized, patients who never had a positive swab for MDRO were defined as noncolonized.
Results: Of 312 AML patients 90 were colonized and 130 were noncolonized. Colonized patients suffered from significantly more days with fever, spent more days on the intensive care unit and had a higher median C-reactive protein value during the hospital stay. These findings did not result in a prolonged length of hospital stay or an increased mortality rate for colonized patients. However, in a subgroup analysis, patients colonized with carbapenem-resistant enterobacteriaceae (CRE) had a significantly reduced 60- and 90-day, as well as 1- and 2-year survival rates when compared to noncolonized patients.
Conclusion: Our analysis highlights the importance of intensive MDRO screening especially in patients with febrile neutropenia since persisting fever can be a sign of MDRO-colonization. CRE-colonized patients require special surveillance, since they seem to be at risk for death.
The deer ked (Lipoptena cervi) is distributed in Europe, North America, and Siberia and mainly infests cervids as roe deer, fallow deer, and moose. From a one health perspective, deer keds occasionally bite other animals or humans and are a potential vector for Bartonella schoenbuchensis. This bacterium belongs to a lineage of ruminant-associated Bartonella spp. and is suspected to cause dermatitis and febrile diseases in humans. In this study, we analyzed the microbiome from 130 deer keds collected from roe deer, fallow deer and humans in the federal states of Hesse, Baden-Wuerttemberg, and Brandenburg, Germany. Endosymbiontic Arsenophonus spp. and Bartonella spp. represented the biggest portion (~90%) of the microbiome. Most Bartonella spp. (n = 93) were confirmed to represent B. schoenbuchensis. In deer keds collected from humans, no Bartonella spp. were detected. Furthermore, Acinetobacter spp. were present in four samples, one of those was confirmed to represent A. baumannii. These data suggest that deer keds harbor only a very narrow spectrum of bacteria which are potentially pathogenic for animals of humans.
Background: Arthropod-borne diseases remain a major health-threat for humans and animals worldwide. To estimate the distribution of pathogenic agents and especially Bartonella spp., we conducted tick microbiome analysis and determination of the infection status of wild animals, pets and pet owners in the state of Hesse, Germany.
Results: In total, 189 engorged ticks collected from 163 animals were tested. Selected ticks were analyzed by next generation sequencing (NGS) and confirmatory PCRs, blood specimens of 48 wild animals were analyzed by PCR to confirm pathogen presence and sera of 54 dogs, one cat and 11 dog owners were analyzed by serology. Bartonella spp. were detected in 9.5% of all ticks and in the blood of 17 roe deer. Further data reveal the presence of the human and animal pathogenic species of genera in the family Spirochaetaceae (including Borrelia miyamotoi and Borrelia garinii), Bartonella spp. (mainly Bartonella schoenbuchensis), Rickettsia helvetica, Francisella tularensis and Anaplasma phagocytophilum in ticks. Co-infections with species of several genera were detected in nine ticks. One dog and five dog owners were seropositive for anti-Bartonella henselae-antibodies and one dog had antibodies against Rickettsia conorii.
Conclusions: This study provides a snapshot of pathogens circulating in ticks in central Germany. A broad range of tick-borne pathogens are present in ticks, and especially in wild animals, with possible implications for animal and human health. However, a low incidence of Bartonella spp., especially Bartonella henselae, was detected. The high number of various detected pathogens suggests that ticks might serve as an excellent sentinel to detect and monitor zoonotic human pathogens.
Background and aims: Spontaneous bacterial peritonitis (SBP) is a severe complication of decompensated cirrhosis. The prevalence of multidrug-resistant organisms (MDROs) in patients with cirrhosis is increasing. Identification of patients at risk for SBP due to MDROs (ie, SBP with the evidence of MDROs or Stenotrophomonas maltophilia in ascitic culture, MDRO-SBP) is crucial to the early adaptation of antibiotic treatment in such patients. We therefore investigated whether MDROs found in ascitic cultures can also be found in specimens determined by noninvasive screening procedures.
Patients and methods: This retrospective study was conducted at the liver center of the University Hospital Frankfurt, Germany. Between 2011 and 2016, patients with cirrhosis were included upon diagnosis of SBP and sample collection of aerobic/anaerobic ascitic cultures. Furthermore, the performance of at least one complete MDRO screening was mandatory for study inclusion.
Results: Of 133 patients diagnosed with SBP, 75 (56.4%) had culture-positive SBP and 22 (16.5%) had MDRO-SBP. Multidrug-resistant Escherichia coli (10/22; 45.5%) and vancomycin-resistant enterococci (7/22; 36.4%) resembled the major causatives of MDRO-SBP. Rectal swabs identified MDROs in 17 of 22 patients (77.3%) who developed MDRO-SBP with a time-dependent sensitivity of 77% and 87% after 30 and 90 days upon testing, while negative predictive value was 83% and 76%, respectively. The majority of patients were included from intensive care unit or intermediate care unit.
Conclusion: MDRO screening may serve as a noninvasive diagnostic tool to identify patients at risk for MDRO-SBP. Patients with decompensated cirrhosis should be screened for MDROs from the first day of inpatient treatment onward.
Allogeneic hematopoietic stem cell transplantation (allo-HSCT) offers potential cure to acute myeloid leukemia (AML) patients. However, infections with commensal bacteria are an important cause for non-relapse mortality (NRM). We have previously described the impact of multidrug-resistant organism (MDRO) colonization on the survival of allo-HSCT patients. In the aforementioned publication, according to consensus, we there did not consider the opportunistic gram-negative bacterium Stenotrophomonas maltophilia (S. maltophilia) to be an MDRO. Since rate of S. maltophilia colonization is increasing, and it is not known whether this poses a risk for allo-HSCT patients, we here analyzed here its effect on the previously described and now extended patient cohort. We report on 291 AML patients undergoing allo-HSCT. Twenty of 291 patients (6.9%) were colonized with S. maltophilia. Colonized patients did not differ from non-colonized patients with respect to their age, remission status before allo-HSCT, donor type and HSCT-comorbidity index. S. maltophilia colonized patients had a worse overall survival (OS) from 6 months up to 60 months (85% vs. 88.1% and 24.7% vs. 59.7%; p = 0.007) due to a higher NRM after allo-HSCT (6 months: 15% vs. 4.8% and 60 months: 40.1% vs. 16.2% p = 0.003). The main cause of mortality in colonized patients was infection (46.2% of all deaths) and in non-colonized patients relapse (58.8% of all deaths). 5/20 colonized patients developed an invasive infection with S. maltophilia. The worse OS after allo-HSCT due to higher infection related mortality might implicate the screening of allo-HSCT patients for S. maltophilia and a closer observation of colonized patients as outpatients.
Molecular detection of Bartonella henselae in 11 Ixodes ricinus ticks extracted from a single cat
(2017)
Background: Bartonella henselae is a highly prevalent, vector-borne pathogen. Transmission to humans and animals by ticks is discussed controversially. Here, we present a case report, where eleven Ixodes ricinus ticks all harbouring B. henselae DNA were removed from one single cat.
Results: The first feeding tick was tested positive for B. henselae DNA. The cat was also found to be seropositive for anti-B. henselae IgG antibodies (titer 1:640). Bartonella henselae was not cultivatable from cat blood. Ten more feeding ticks removed 7 months later contained also B. henselae DNA. Sequence analysis of the 16SrDNA and the 16S-23S internal transcribed spacer (ITS) region revealed 100% sequence homology between all ticks. Bartonella adhesin A (badA) and VirB/VirD4 type IV secretion system (virB) DNA were also detected in all ticks.
Conclusions: Our results indicate that cats may serve as a reservoir for adult ticks to acquire B. henselae. Whether this observation implies an increased threat for human and animal health needs to be resolved.
Infectious diseases remain a remarkable health threat for humans and animals. In the past, the epidemiology, etiology and pathology of infectious agents affecting humans and animals have mostly been investigated in separate studies. However, it is evident, that combined approaches are needed to understand geographical distribution, transmission and infection biology of “zoonotic agents”. The genus Bartonella represents a congenial example of the synergistic benefits that can arise from such combined approaches: Bartonella spp. infect a broad variety of animals, are linked with a constantly increasing number of human diseases and are transmitted via arthropod vectors. As a result, the genus Bartonella is predestined to play a pivotal role in establishing a One Health concept combining veterinary and human medicine.
Massive global spread of multidrug-resistant (MDR) Salmonella spp. expressing extended-spectrum beta-lactamase (ESBL) and additional resistance to fluoroquinolones has often been attributed to high international mobility as well as excessive use of oral antibiotics in livestock farming. However, MDR Salmonella spp. have not been mentioned as a widespread pathogen in clinical settings so far. We demonstrate the case of a 25-year-old male with primary sclerosing cholangitis who tested positive for MDR Salmonella enterica serotype Choleraesuis expressing ESBL and fluoroquinolone resistance. The pathogen was supposedly acquired during a trip to Thailand, causing severe fever, cholangitis and pancreatitis. To our knowledge, this is the first report of Salmonella enterica serotype Choleraesuis in Europe expressing such a multidrug resistance pattern. ESBL resistance of Salmonella enterica spp. should be considered in patients with obstructive biliary tract pathology and travel history in endemic countries.
Influence of antibiotic-regimens on intensive-care unit-mortality and liver-cirrhosis as risk factor
(2016)
AIM: To assess the rate of infection, appropriateness of antimicrobial-therapy and mortality on intensive care unit (ICU). Special focus was drawn on patients with liver cirrhosis.
METHODS: The study was approved by the local ethical committee. All patients admitted to the Internal Medicine-ICU between April 1, 2007 and December 31, 2009 were included. Data were extracted retrospectively from all patients using patient charts and electronic documentations on infection, microbiological laboratory reports, diagnosis and therapy. Due to the large hepatology department and liver transplantation center, special interest was on the subgroup of patients with liver cirrhosis. The primary statistical-endpoint was the evaluation of the influence of appropriate versus inappropriate antimicrobial-therapy on in-hospital-mortality.
RESULTS: Charts of 1979 patients were available. The overall infection-rate was 53%. Multiresistant-bacteria were present in 23% of patients with infection and were associated with increased mortality (P < 0.000001). Patients with infection had significantly increased in-hospital-mortality (34% vs 17%, P < 0.000001). Only 9% of patients with infection received inappropriate initial antimicrobial-therapy, no influence on mortality was observed. Independent risk-factors for in-hospital-mortality were the presence of septic-shock, prior chemotherapy for malignoma and infection with Pseudomonas spp. Infection and mortality-rate among 175 patients with liver-cirrhosis was significantly higher than in patients without liver-cirrhosis. Infection increased mortality 2.24-fold in patients with cirrhosis. Patients with liver cirrhosis were at an increased risk to receive inappropriate initial antimicrobial therapy.
CONCLUSION: The results of the present study report the successful implementation of early-goal-directed therapy. Liver cirrhosis patients are at increased risk of infection, mortality and to receive inappropriate therapy. Increasing burden are multiresistant-bacteria.
Background: The federal state of Hesse, Germany, introduced a laboratory-based reporting scheme for carbapenem-resistant organisms (CROs).
Method: The results of the first year of mandated reporting of CROs from April 2012 through March 2013 to the Public Health Authority of Frankfurt/Main, responsible for a population of 700,000 inhabitants, are described.
Results: Within a period of 12 months 243 CROs were notified to the health authority. Of these 213 isolates had been reported from 16 of the 17 hospitals in Frankfurt/Main, 6 from ambulatory settings and 24 from clinics outside of Frankfurt/Main. Mean incidence rate per 1,000 patient days in hospitals was 0.138 (range 0.02-0.28).
Conclusion: In Frankfurt/Main almost all hospitals have reported CROs in the study period though the frequency of isolation varies strongly and many facilities only report CROs sporadically. Molecular data indicate a high diversity of different carbapenemases. Autochthonous transmission must be assumed despite the absence of major outbreaks. Rapid and coordinated efforts by clinicians and health departments are crucial to control the spread of CRO infections. The mandatory reporting scheme provides important data to guide the implementation of preventive measures.
Activation of hypoxia inducible factor 1 is a general phenomenon in infections with human pathogens
(2010)
Background: Hypoxia inducible factor (HIF)-1 is the key transcriptional factor involved in the adaptation process of cells and organisms to hypoxia. Recent findings suggest that HIF-1 plays also a crucial role in inflammatory and infectious diseases. Methodology/Principal Findings: Using patient skin biopsies, cell culture and murine infection models, HIF-1 activation was determined by immunohistochemistry, immunoblotting and reporter gene assays and was linked to cellular oxygen consumption. The course of a S. aureus peritonitis was determined upon pharmacological HIF-1 inhibition. Activation of HIF-1 was detectable (i) in all ex vivo in biopsies of patients suffering from skin infections, (ii) in vitro using cell culture infection models and (iii) in vivo using murine intravenous and peritoneal S. aureus infection models. HIF-1 activation by human pathogens was induced by oxygen-dependent mechanisms. Small colony variants (SCVs) of S. aureus known to cause chronic infections did not result in cellular hypoxia nor in HIF-1 activation. Pharmaceutical inhibition of HIF-1 activation resulted in increased survival rates of mice suffering from a S. aureus peritonitis. Conclusions/Significance: Activation of HIF-1 is a general phenomenon in infections with human pathogenic bacteria, viruses, fungi and protozoa. HIF-1-regulated pathways might be an attractive target to modulate the course of life-threatening infections.
Bei gesunden Menschen verläuft die Infektion mit Bartonella henselae als vergleichsweise harmlose "Katzenkratzkrankheit". Erst mit Beginn der AIDS-Pandemie zeigte sich, dass das Bakterium bei immungeschwächten Patienten auch die pathologische Neubildung von Blutgefäßen auslösen kann. Diese Pathogenitätsstrategie unterscheidet die Spezies der Bartonellen von allen anderen bakteriellen Infektionserregern des Menschen. Für Mikrobiologen ist Bartonella henselae deshalb ein interessanter Modellorganismus, weil Blutgefäßwachstum in erster Linie eine Domäne der Tumorforschung ist.
Adhesion and host cell modulation: critical pathogenicity determinants of Bartonella henselae
(2011)
Bartonella henselae, the agent of cat scratch disease and the vasculoproliferative disorders bacillary angiomatosis and peliosis hepatis, contains to date two groups of described pathogenicity factors: adhesins and type IV secretion systems. Bartonella adhesin A (BadA), the Trw system and possibly filamentous hemagglutinin act as promiscous or specific adhesins, whereas the virulence locus (Vir)B/VirD4 type IV secretion system modulates a variety of host cell functions. BadA mediates bacterial adherence to endothelial cells and extracellular matrix proteins and triggers the induction of angiogenic gene programming. The VirB/VirD4 type IV secretion system is responsible for, e.g., inhibition of host cell apoptosis, bacterial persistence in erythrocytes, and endothelial sprouting. The Trw-conjugation system of Bartonella spp. mediates host-specific adherence to erythrocytes. Filamentous hemagglutinins represent additional potential pathogenicity factors which are not yet characterized. The exact molecular functions of these pathogenicity factors and their contribution to an orchestral interplay need to be analyzed to understand B. henselae pathogenicity in detail.