Epidemiology and infection control of carbapenem resistant Acinetobacter baumannii and Klebsiella pneumoniae at a German university hospital: a retrospective study of 5 years (2015-2019).

BACKGROUND: Carbapenem resistant (CR) Klebsiella pneumoniae (Kp) and Acinetobacter baumannii (Ab) are emerging multidrug resistant bacteria with very limited treatment options in case of infection. Both are well-known causes of nosocomial infections and outbreaks in healthcare facilities. METHODS: A retrospective study was conducted to investigate the epidemiology of inpatients with CR Kp and CR Ab in a 1500-bed German university hospital from 2015 to 2019. We present our infection control concept including a weekly microbiologic screening for patients who shared the ward with a CR Kp or CR Ab index patient. RESULTS: Within 5 years, 141 CR Kp and 60 CR Ab cases were hospitalized corresponding to 118 unique patients (74 patients with CR Kp, 39 patients with CR Ab and 5 patients with both CR Ab and CR Kp). The mean incidence was 0.045 (CR Kp) and 0.019 (CR Ab) per 100 inpatient cases, respectively. Nosocomial acquisition occurred in 53 cases (37.6%) of the CR Kp group and in 12 cases (20.0%) of the CR Ab group. Clinical infection occurred in 24 cases (17.0%) of the CR Kp group and in 21 cases (35.0%) of the CR Ab group. 14 cases (9.9%) of the CR Kp group and 29 cases (48.3%) of the CR Ab group had a history of a hospital stay abroad within 12 months prior to admission to our hospital. The weekly microbiologic screening revealed 4 CR Kp cases caused by nosocomial transmission that would have been missed without repetitive screening. CONCLUSIONS: CR Kp and CR Ab cases occurred infrequently. A history of a hospital stay abroad, particularly in the CR Ab group, warrants pre-emptive infection control measures. The weekly microbiologic screening needs further evaluation in terms of its efficiency.

Hematopoietic stem cell gene therapy for IFNγR1 deficiency protects mice from mycobacterial infections.

Mendelian susceptibility to mycobacterial disease is a rare primary immunodeficiency characterized by severe infections caused by weakly virulent mycobacteria. Biallelic null mutations in genes encoding interferon gamma receptor 1 or 2 (IFNGR1 or IFNGR2) result in a life-threatening disease phenotype in early childhood. Recombinant interferon γ (IFN-γ) therapy is inefficient, and hematopoietic stem cell transplantation has a poor prognosis. Thus, we developed a hematopoietic stem cell (HSC) gene therapy approach using lentiviral vectors that express Ifnγr1 either constitutively or myeloid specifically. Transduction of mouse Ifnγr1-/- HSCs led to stable IFNγR1 expression on macrophages, which rescued their cellular responses to IFN-γ. As a consequence, genetically corrected HSC-derived macrophages were able to suppress T-cell activation and showed restored antimycobacterial activity against Mycobacterium avium and Mycobacterium bovis Bacille Calmette-Guérin (BCG) in vitro. Transplantation of genetically corrected HSCs into Ifnγr1-/- mice before BCG infection prevented manifestations of severe BCG disease and maintained lung and spleen organ integrity, which was accompanied by a reduced mycobacterial burden in lung and spleen and a prolonged overall survival in animals that received a transplant. In summary, we demonstrate an HSC-based gene therapy approach for IFNγR1 deficiency, which protects mice from severe mycobacterial infections, thereby laying the foundation for a new therapeutic intervention in corresponding human patients.

Epidemiologic and Molecular Investigation of a MRSA Outbreak Caused by a Contaminated Bathtub for Carbon Dioxide Hydrotherapy and Review of the Literature.

METHODS: We conducted an outbreak investigation and performed a molecular typing of the outbreak strains with pulsed-field gel electrophoresis (PFGE). In addition, we reviewed PubMed and the Outbreak Database for MRSA outbreaks related to hydrotherapy or other bathing activities. RESULTS: Four patients acquired nosocomial MRSA during the 4-week outbreak period. Environmental sampling revealed the presence of MRSA in the bathtub used for hydrotherapy. The environmental and the patients' isolates showed an indistinguishable restriction pattern in the PFGE. Subsequent discontinuation of bathing stopped the outbreak. The literature search found 9 MRSA outbreak reports related to bathing activities or hydrotherapy. CONCLUSION: The epidemiologic outbreak investigation together with the molecular findings suggests monoclonal spread of MRSA due to surface contamination of the bathtub. After enhancing the disinfection and cleaning process accompanied by staff training with respect to hand hygiene, no further cases occurred. Standardized and best practice cleaning and disinfection protocols are crucial, especially in critical facilities such as hydrotherapy units. Regular environmental sampling is helpful to monitor these processes and to detect potential contamination.

Horizontal acquisition of a hypoxia-responsive molybdenum cofactor biosynthesis pathway contributed to Mycobacterium tuberculosis pathoadaptation.

The unique ability of the tuberculosis (TB) bacillus, Mycobacterium tuberculosis, to persist for long periods of time in lung hypoxic lesions chiefly contributes to the global burden of latent TB. We and others previously reported that the M. tuberculosis ancestor underwent massive episodes of horizontal gene transfer (HGT), mostly from environmental species. Here, we sought to explore whether such ancient HGT played a part in M. tuberculosis evolution towards pathogenicity. We were interested by a HGT-acquired M. tuberculosis-specific gene set, namely moaA1-D1, which is involved in the biosynthesis of the molybdenum cofactor. Horizontal acquisition of this gene set was striking because homologues of these moa genes are present all across the Mycobacterium genus, including in M. tuberculosis. Here, we discovered that, unlike their paralogues, the moaA1-D1 genes are strongly induced under hypoxia. In vitro, a M. tuberculosis moaA1-D1-null mutant has an impaired ability to respire nitrate, to enter dormancy and to survive in oxygen-limiting conditions. Conversely, heterologous expression of moaA1-D1 in the phylogenetically closest non-TB mycobacterium, Mycobacterium kansasii, which lacks these genes, improves its capacity to respire nitrate and grants it with a marked ability to survive oxygen depletion. In vivo, the M. tuberculosis moaA1-D1-null mutant shows impaired survival in hypoxic granulomas in C3HeB/FeJ mice, but not in normoxic lesions in C57BL/6 animals. Collectively, our results identify a novel pathway required for M. tuberculosis resistance to host-imposed stress, namely hypoxia, and provide evidence that ancient HGT bolstered M. tuberculosis evolution from an environmental species towards a pervasive human-adapted pathogen.

GenoType NTM-DR for Identifying Mycobacterium abscessus Subspecies and Determining Molecular Resistance.

We studied the performance of a new line probe assay for identifying the subspecies and determining the macrolide and aminoglycoside resistance levels of 50 Mycobacterium abscessus isolates. Agreement of GenoType NTM-DR results with sequencing and phenotypic resistance results was 92% for subspecies identification and 98% for determining molecular and phenotypic resistance.

Principal component analysis of MALDI TOF MS mass spectra separates M. abscessus (sensu stricto) from M. massiliense isolates.

BACKGROUND: The discrimination of the members of the Mycobacterium abscessus complex is of clinical interest because one of the subspecies, M. massiliense, exhibits higher rates of response to antibiotic treatment for lung infection than do the other members of that complex. M. abscessus complex contains three subspecies that are laborious to identify; therefore, a routine diagnostic tool would be worthwhile. RESULTS: We used principal component analysis, hierarchical cluster analysis, and single-peak analysis to examine peak lists derived from matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) mass spectra of 50 clinical M. abscessus complex isolates, including 28 M. abscessus (sensu stricto), 19 M. massiliense, and 3 M. bolletii isolates grown in mycobacterium growth indicator tube liquid medium and prepared with a bead-based protocol. Principal component analysis but not hierarchical cluster analysis separated M. abscessus (sensu stricto) isolates and M. massiliense isolates into two clusters. Furthermore, single-peak analysis displayed 4 discriminating peaks that separated M. abscessus (sensu stricto) from M. massiliense isolates. M. bolletii isolates did not exhibit specific peaks but resembled the M. abscessus (sensu stricto) peak profile and also grouped within this principal component analysis cluster. Principal component analysis of all peak lists with the exclusion of the four discriminating peaks again separated M. abscessus (sensu stricto) from M. massiliense isolates, thus relativizing the importance of these peaks for subspecies identification. CONCLUSIONS: Principal component analysis of peak lists derived from MALDI TOF mass spectra is a robust and convenient method of discriminating M. massiliense isolates from the other members of the M. abscessus complex.

Systemic complement activation and complement gene analysis in enterohaemorrhagic Escherichia coli-associated paediatric haemolytic uraemic syndrome.

BACKGROUND: In contrast to atypical haemolytic uraemic syndrome (aHUS), only single case reports and limited data have been published on systemic activation of the complement system and mutations in complement genes in paediatric enterohaemorrhagic Escherichia coli-induced HUS (EHEC-HUS). METHODS: Complement activation (CH50, APH50, C3d, sC5b-9) was analysed at four timepoints (Week 1, Week 2, Month 3 and Month 6 after primary diagnosis of HUS) in 25 children with EHEC-HUS. Seven patients received the complement C5 inhibitor eculizumab. Targeted next generation sequencing for a total of 89 genes involved in complement regulation and coagulation and haemostasis was performed in all patients. RESULTS: Activity of classical (CH50) and alternative (APH50) complement pathways was normal or even elevated throughout the observation time, except for patients under eculizumab treatment. In contrast, the mean concentration of the soluble terminal complement complex (sC5b-9) was significantly elevated at the first timepoint (mean 498 ng/mL), dropping to normal values after 2 weeks. Initially elevated (42 mU/L) median C3d concentration reached normal levels from Week 2. Levels of sC5b-9 >320 ng/mL at the time of HUS diagnosis were associated with arterial hypertension, oedema and lower platelet counts, but not with the duration of dialysis. Genetic analysis revealed various changes that may have had a modifying impact on the clinical course. CONCLUSIONS: Complement activation at the acute phase of EHEC-HUS, indicated by increased levels of sC5b-9, predicts a poor outcome. Complement alterations appear to be more frequent in patients with EHEC-HUS than previously thought and are suspected to have a role in the severity of the disease.

Effects of Halide Ions on the Carbamidocyclophane Biosynthesis in Nostoc sp. CAVN2.

In this study, the influence of halide ions on [7.7]paracyclophane biosynthesis in the cyanobacterium Nostoc sp. CAVN2 was investigated. In contrast to KI and KF, supplementation of the culture medium with KCl or KBr resulted not only in an increase of growth but also in an up-regulation of carbamidocyclophane production. LC-MS analysis indicated the presence of chlorinated, brominated, but also non-halogenated derivatives. In addition to 22 known cylindrocyclophanes and carbamidocyclophanes, 27 putative congeners have been detected. Nine compounds, carbamidocyclophanes M-U, were isolated, and their structural elucidation by 1D and 2D NMR experiments in combination with HRMS and ECD analysis revealed that they are brominated analogues of chlorinated carbamidocyclophanes. Quantification of the carbamidocyclophanes showed that chloride is the preferably utilized halide, but incorporation is reduced in the presence of bromide. Evaluation of the antibacterial activity of 30 [7.7]paracyclophanes and related derivatives against selected pathogenic Gram-positive and Gram-negative bacteria exhibited remarkable effects especially against methicillin- and vancomycin-resistant staphylococci and Mycobacterium tuberculosis. For deeper insights into the mechanisms of biosynthesis, the carbamidocyclophane biosynthetic gene cluster in Nostoc sp. CAVN2 was studied. The gene putatively coding for the carbamoyltransferase has been identified. Based on bioinformatic analyses, a possible biosynthetic assembly is discussed.

Acetate Dissimilation and Assimilation in Mycobacterium tuberculosis Depend on Carbon Availability.

UNLABELLED: Mycobacterium tuberculosis persists inside granulomas in the human lung. Analysis of the metabolic composition of granulomas from guinea pigs revealed that one of the organic acids accumulating in the course of infection is acetate (B. S. Somashekar, A. G. Amin, C. D. Rithner, J. Troudt, R. Basaraba, A. Izzo, D. C. Crick, and D. Chatterjee, J Proteome Res 10:4186-4195, 2011, doi:http://dx.doi.org/10.1021/pr2003352), which might result either from metabolism of the pathogen or might be provided by the host itself. Our studies characterize a metabolic pathway by which M. tuberculosis generates acetate in the cause of fatty acid catabolism. The acetate formation depends on the enzymatic activities of Pta and AckA. Using actyl coenzyme A (acetyl-CoA) as a substrate, acetyl-phosphate is generated and finally dephosphorylated to acetate, which is secreted into the medium. Knockout mutants lacking either the pta or ackA gene showed significantly reduced acetate production when grown on fatty acids. This effect is even more pronounced when the glyoxylate shunt is blocked, resulting in higher acetate levels released to the medium. The secretion of acetate was followed by an assimilation of the metabolite when other carbon substrates became limiting. Our data indicate that during acetate assimilation, the Pta-AckA pathway acts in concert with another enzymatic reaction, namely, the acetyl-CoA synthetase (Acs) reaction. Thus, acetate metabolism might possess a dual function, mediating an overflow reaction to release excess carbon units and resumption of acetate as a carbon substrate. IMPORTANCE: During infection, host-derived lipid components present the major carbon source at the infection site. ß-Oxidation of fatty acids results in the formation of acetyl-CoA. In this study, we demonstrate that consumption of fatty acids by Mycobacterium tuberculosis activates an overflow mechanism, causing the pathogen to release excess carbon intermediates as acetate. The Pta-AckA pathway mediating acetate formation proved to be reversible, enabling M. tuberculosis to reutilize the previously secreted acetate as a carbon substrate for metabolism.

Characterization of rough and smooth morphotypes of Mycobacterium abscessus isolates from clinical specimens.

Mycobacterium abscessus, which consists of the two subspecies M. abscessus subspecies abscessus and M. abscessus subspecies bolletii, can produce rough or smooth colony morphologies. Here we analyzed 50 M. abscessus isolates cultured from the respiratory specimens of 34 patients, 28 (82%) of whom had cystic fibrosis (CF), with respect to their colony morphologies and antibiotic susceptibilities. The overall proportions of occurrences of the two morphotypes were similar, with specimens from 50% of the patients showing a rough and 38% showing a smooth morphotype. A total of 12% of the specimens from the patients showed both morphotypes simultaneously. At the subspecies level, the proportions of rough and smooth morphotypes differed substantially; 88% of rough morphotypes belonged to M. abscessus subspecies abscessus, and 85% of smooth morphotypes belonged M. abscessus subspecies bolletii. Inducible clarithromycin resistance due to the Erm(41) methylase, as well as high-level resistance to clarithromycin due to mutations within the rrl gene, occurred independently of the morphotype. The MIC50s of amikacin and cefoxitin were identical for the two morphotypes, whereas the MIC50s of tigecycline were 0.25 µg/ml for the rough morphotype and 2.0 µg/ml for the smooth morphotype. Our results show that the smooth morphotype was more dominant in respiratory specimens from CF patients than previously thought. With respect to resistance, colony morphology did not affect the susceptibility of Mycobacterium abscessus to the first-line antibiotics clarithromycin, amikacin, and cefoxitin.

Ultrasound presentation of abdominal tuberculosis in a German tertiary care center.

OBJECTIVE: Abdominal tuberculosis (TB) is a relatively rare disease in most of Europe and the typical clinical and sonographic findings in this setting have not been studied. We aimed to define sonographic findings that should alert an examiner to the possibility of abdominal TB in a low endemic region. METHODS: Case records of 17 patients with proven (n = 11) or highly likely (n = 6) abdominal TB detected in the gastrointestinal ultrasound unit at a German tertiary care center in 2003-2013 were analyzed retrospectively. Findings were compared with reported series from high-prevalence regions. RESULTS: While 76% of patients had an immigrant background, only 35% had a condition associated with immunosuppression. Lymphadenopathy was present in all cases of abdominal TB, while it was absent in 28% of patients from a control group with proven abdominal sarcoidosis. Moreover, retroperitoneal lymphadenopathy was significantly more common in TB. Other findings in patients with abdominal TB in descending order of frequency were ascites, altered hepatic texture, splenomegaly, splenic lesions, peritoneal thickening, intestinal wall lesions, hepatic lesions and hepatomegaly. 76% of abdominal TB patients had 2 or more pathological findings. CONCLUSIONS: Multiple pathological intra-abdominal findings including lymphadenopathy should alert the examiner to the possibility of abdominal TB.

Epidemiology and infection control of vancomycin-resistant enterococci at a German university hospital: A three-year retrospective cohort study.

Vancomycin-resistant enterococci (VRE) occur in hospitalized patients, causing both infection and colonization. In recent years, there has been an increase in VRE in German and other hospitals, raising the question of how to control this epidemic best. To better understand the specific epidemiology and to guide infection control, we conducted a retrospective cohort study analyzing all patients with VRE at Hannover Medical School, a tertiary university clinic in Germany that specializes in solid organ transplantation. Epidemiologic and clinical characteristics of patients with VRE from 2015-2017 were collected. Basic epidemiologic parameters, including VRE incidence and incidence density, were calculated. Independent risk factors for nosocomial VRE infection compared to colonization were assessed using a logistic regression model. There were 1,492 VRE cases corresponding to 822 individual patients. The incidence was 0.8 VRE cases per 100 cases. A total of 536 (35.9%) of the 1,492 VRE cases were acquired nosocomially. Of the 1,492 cases, 912 cases had VRE-positive samples (894 Enterococcus (E.) faecium and 18 E. faecalis) in our hospital laboratory and the remaining cases were known VRE carriers. The vanB-phenotype was observed in 369 of the 894 (41.3%) E. faecium isolates and in 6 of the 18 (33.3%) E. faecalis isolates. There was an increase over time in the vanB-phenotype proportion in E. faecium (2015: 63 of 171, 36.8%, 2016: 115 of 322, 35.7% and 2017: 191 of 401, 47.6%). A total of 107 cases had a VRE infection (7.2% of all VRE cases) according to the criteria of the German National Reference Center for Surveillance of Nosocomial Infections. The remaining cases were only colonized. Among other factors, leukocytopenia (<1,000/µL), the use of a central venous catheter and the visceral surgery medical specialty were independently associated with nosocomial VRE infection. VRE imposed a relevant and increasing infection control burden at our hospital. Nosocomial VRE infection was predominantly found in certain medical specialties, such as hematology and oncology and visceral surgery. Infection control efforts should focus on these highly affected patient groups/specialties.

The intracellular environment of human macrophages that produce nitric oxide promotes growth of mycobacteria.

Nitric oxide (NO) is a diffusible radical gas produced from the activity of nitric oxide synthase (NOS). NOS activity in murine macrophages has a protective role against mycobacteria through generation of reactive nitrogen intermediates (RNIs). However, the production of NO by human macrophages has remained unclear due to the lack of sensitive reagents to detect NO directly. The purpose of this study was to investigate NO production and the consequence to mycobacteria in primary human macrophages. We found that Mycobacterium bovis BCG or Mycobacterium tuberculosis infection of human macrophages induced expression of NOS2 and NOS3 that resulted in detectable production of NO. Treatment with gamma interferon (IFN-γ), l-arginine, and tetrahydrobiopterin enhanced expression of NOS2 and NOS3 isoforms, as well as NO production. Both of these enzymes were shown to contribute to NO production. The maximal level of NO produced by human macrophages was not bactericidal or bacteriostatic to M. tuberculosis or BCG. The number of viable mycobacteria was increased in macrophages that produced NO, and this requires expression of nitrate reductase. An narG mutant of M. tuberculosis persisted but was unable to grow in human macrophages. Taken together, these data (i) enhance our understanding of primary human macrophage potential to produce NO, (ii) demonstrate that the level of RNIs produced in response to IFN-γ in vitro is not sufficient to limit intracellular mycobacterial growth, and (iii) suggest that mycobacteria may use RNIs to enhance their survival in human macrophages.

Biotin sulfoxide reductase contributes to oxidative stress tolerance and virulence in Salmonella enterica serovar Typhimurium.

Oxidative stress converts sulfur residues of molecules like biotin and methionine into their oxidized forms. Here we show that the biotin sulfoxide reductase BisC of Salmonella enterica serovar Typhimurium (S. Typhimurium) repairs both oxidized biotin and oxidized methionine. Exposure to H2O2 in vitro reduced survival of a S. Typhimurium ΔbisC mutant. Furthermore, replication of the ΔbisC mutant inside IFN-γ activated macrophages was reduced. In vitro tolerance of the mutant to H2O2 was restored by plasmids carrying either bisC or msrA; the latter encodes a methioinine sulfoxide reductase. In contrast, the proliferation defect inside IFN-γ activated macrophages was rescued by bisC but not by msrA. Thus growth of the ΔbisC mutant in IFN-γ activated macrophages required repair of oxidized biotin. Both the ΔbisC and a biotin auxotrophic (ΔbioB) mutant were attenuated in mice, suggesting that besides biotin biosynthesis, biotin repair was essential for virulence of S. Typhimurium in vivo. Attenuation of the ΔbisC mutant was more pronounced in 129 mice that produce a stronger oxidative response. These results show that BisC is essential for full virulence of Salmonella by contributing to the defence of S. Typhimurium against host-derived stress, and provides an attractive drug target since it is not present in mammals.

Metabolic adaptation of Mycobacterium avium subsp. paratuberculosis to the gut environment.

Knowledge on the proteome level about the adaptation of pathogenic mycobacteria to the environment in their natural hosts is limited. Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne's disease, a chronic and incurable granulomatous enteritis of ruminants, and has been suggested to be a putative aetiological agent of Crohn's disease in humans. Using a comprehensive LC-MS-MS and 2D difference gel electrophoresis (DIGE) approach, we compared the protein profiles of clinical strains of MAP prepared from the gastrointestinal tract of diseased cows with the protein profiles of the same strains after they were grown in vitro. LC-MS-MS analyses revealed that the principal enzymes for the central carbon metabolic pathways, including glycolysis, gluconeogenesis, the tricaboxylic acid cycle and the pentose phosphate pathway, were present under both conditions. Moreover, a broad spectrum of enzymes for ß-oxidation of lipids, nine of which have been shown to be necessary for mycobacterial growth on cholesterol, were detected in vivo and in vitro. Using 2D-DIGE we found increased levels of several key enzymes that indicated adaptation of MAP to the host. Among these, FadE5, FadE25 and AdhB indicated that cholesterol is used as a carbon source in the bovine intestinal mucosa; the respiratory enzymes AtpA, NuoG and SdhA suggested increased respiration during infection. Furthermore higher levels of the pentose phosphate pathway enzymes Gnd2, Zwf and Tal as well as of KatG, SodA and GroEL indicated a vigorous stress response of MAP in vivo. In conclusion, our results provide novel insights into the metabolic adaptation of a pathogenic mycobacterium in its natural host.

Burden and trends of hospitalisations associated with pulmonary non-tuberculous mycobacterial infections in Germany, 2005-2011.

BACKGROUND: Representative population-based data on the epidemiology of pulmonary non-tuberculous mycobacterial (PNTM) infections in Europe are limited. However, these data are needed in order to optimise patient care and to facilitate the allocation of healthcare resources. The aim of the present study was to investigate the current burden and the trends of PNTM infection-associated hospitalisations in Germany. METHODS: International Classification of Diseases, 10th revision (ICD-10) discharge diagnosis codes were extracted from the official nationwide diagnosis-related groups (DRG) hospital statistics in order to identify PNTM infection-associated hospitalisations (ICD-10 code A31.0) between 2005 and 2011. Poisson log-linear regression analysis was used to assess the significance of trends. RESULTS: Overall, 5,959 records with PNTM infection as any hospital discharge diagnosis were extracted from more than 125 million hospitalisations. The average annual age-adjusted rate was 0.91 hospitalisations per 100,000 population. Hospitalisation rates increased during the study period for both males and females, with the highest rate of 3.0 hospitalisations per 100,000 population among elderly men, but the most pronounced average increase of 6.4%/year among females, particularly those of young and middle age, and hospitalisations associated with cystic fibrosis. Overall, chronic obstructive pulmonary disease (COPD) was the most frequent PNTM infection-associated condition in 28.9% of hospitalisations and also showed a significant average annual increase of 4.8%. CONCLUSIONS: The prevalence of PNTM infection-associated hospitalisations is steadily increasing in Germany. COPD is currently the most important associated condition. Our population-based study provides evidence of a changing epidemiology of PNTM infections and highlights emerging clinical implications.

Target capture sequencing reveals a monoclonal outbreak of respiratory syncytial virus B infections among adult hematologic patients.

BACKGROUND: Respiratory syncytial virus (RSV) causes community-acquired respiratory tract infections during winter. However, outbreaks in hospitals also occur repeatedly. In particular, patients with hematologic malignancies are at an increased risk for a severe and potentially fatal course of RSV infection. Here we present the investigation of an RSV outbreak in a hematology ward for adults following the ORION statement. METHODS: An epidemiologic and molecular outbreak analysis was performed. We developed and employed a minimal oligonucleotide probe set in target capture probe sequencing that allows cost-effective RSV-A or -B capturing to reconstruct RSV genomes from clinical samples. RESULTS: Four adult patients were involved in the outbreak caused by RSV-B in March 2019. The enforcement of the pre-existing infection control measures by effective training of hospital staff contributed to a successful containment. PCR-based RSV screening on the ward enabled early detection of new cases and rapid isolation measures. The molecular analysis demonstrated that the outbreak sequences were highly related and distinct to other RSV-B strains circulating at the same time. CONCLUSIONS: A multimodal infection control concept is essential for the timely detection and control of RSV outbreaks in patients with hematological disease. Among other measures, preventive screening for respiratory viruses is recommended. Furthermore, the integration of conventional and molecular epidemiology, such as whole-genome sequencing and variant calling, significantly contributes to the understanding of transmission pathways. Based on this, appropriate conclusions can be drawn for targeted prevention measures that have prepared us for the COVID-19 pandemic beyond the RSV approach described here.

Epidemiology and infection control of Methicillin-resistant Staphylococcus aureus in a German tertiary neonatal intensive and intermediate care unit: A retrospective study (2013-2020).

In preterm and term infants who require intermediate or intensive care Methicillin-resistant Staphylococcus aureus (MRSA) infection can lead to significant morbidity. In this study MRSA colonization and infection were assessed in a mixed tertiary neonatal intensive and intermediate care unit in Germany over an 8-year period (2013-2020). We investigated patient-related factors, associated with nosocomial MRSA acquisition, and we discuss our infection control concept for MRSA. Of 3488 patients treated during the study period, 24 were MRSA positive patients, corresponding to 26 patient hospital stays. The incidence was 0.7 MRSA patients per 100 patients. The incidence density was 0.4 MRSA patient hospital stays per 1000 patient days. Twelve patients (50%) acquired MRSA in the hospital. One patient developed a hospital acquired MRSA bloodstream infection 9 days after birth (i.e., 0.03% of all patients on the ward during the study period). A total of 122 patients had to be screened to detect one MRSA positive patient. In a logistic regression model, the use of 3rd generation intravenous cephalosporin (cefotaxim) was associated with nosocomial MRSA acquisition compared with matched control patients who did not acquire MRSA. In sum, the burden of MRSA colonization and infection in the ward was low during the study period. A comprehensive infection control concept that included microbiologic colonization screening, prospective infection surveillance together with isolation and emphasis on basic hygiene measures is essential to handle MRSA in this specialized setting.

Detection of Serratia marcescens in neonatal intensive care units requires a rapid and comprehensive infection control response starting with the very first case.

Background: Serratia marcescens is a well-known and challenging pathogen in neonatal intensive care units. It is responsible for severe infections and can cause nosocomial outbreaks. Methods: We present the infection control response to a Serratia marcescens cluster which occurred in a tertiary neonatal intensive care unit. Results and conclusions: The presented comprehensive and decisive hygiene management response starting with the very first case aims especially at early detection and immediate interruption of nosocomial transmission. Frequent and sensitive microbiological screening, rigorous spatial isolation of colonized infants, and reinforcing adherence to hand hygiene are essential in this response, which comprises eight measures. It prevented a full-blown outbreak.

Thiol peroxidase protects Salmonella enterica from hydrogen peroxide stress in vitro and facilitates intracellular growth.

At present, Salmonella is considered to express two peroxiredoxin-type peroxidases, TsaA and AhpC. Here we describe an additional peroxiredoxin, Tpx, in Salmonella enterica and show that a single tpx mutant is susceptible to exogenous hydrogen peroxide (H(2)O(2)), that it has a reduced capacity to degrade H(2)O(2) compared to the ahpCF and tsaA mutants, and that its growth is affected in activated macrophages. These results suggest that Tpx contributes significantly to the sophisticated defense system that the pathogen has evolved to survive oxidative stress.