Martin Mielke

Prevalence and role of serum IgE antibodies to the StaphylococcuS aureus–derived superantigens SEA and SEB in children with atopic dermatitis

BACKGROUND The skin of patients with atopic dermatitis exhibits a striking susceptibility to colonization and infection with Staphylococcus aureus. In this context it has been previously shown that S aureus-derived superantigens could function as classic allergens, inducing production of functionally relevant specific IgE antibodies. OBJECTIVE The aim of this study was to determine the prevalence and the role of circulating staphylococcal enterotoxin A (SEA)- and staphylococcal enterotoxin B (SEB)-specific IgE antibodies in children with atopic dermatitis. METHODS In a cross-sectional study of 58 children with atopic dermatitis, the presence of IgE antibodies to SEA and SEB was correlated with the severity of the disease and the total and other unrelated allergen-specific IgE titers and density of colonization with S aureus strains on atopic skin and episodes of superficial S aureus skin infections. RESULTS Twenty of 58 children (34%) were sensitized to superantigens (45% to SEB, 10% to SEA, 45% to SEA and SEB). In this group, severity of atopic dermatitis and levels of specific IgE to food and air allergens were significantly higher. The degree of disease severity correlated to a higher extent with the presence of SEA/SEB-specific antibodies than with total serum IgE levels. Density of colonization with superantigen-secreting S aureus strains was higher in the superantigen IgE-positive group. Sixty-three percent of these children experienced repeated episodes of superficialS aureus skin infections. CONCLUSIONS Sensitization to S aureus-derived superantigens may be involved in disease exacerbation. The presence of SEA/SEB-specific antibodies had additional explanatory value for disease severity and therefore may be helpful in the characterization of children with severe atopic dermatitis.

Communicable Diseases Prioritized for Surveillance and Epidemiological Research: Results of a Standardized Prioritization Procedure in Germany, 2011

Introduction To establish strategic priorities for the German national public health institute (RKI) and guide the institutes mid-term strategic decisions, we prioritized infectious pathogens in accordance with their importance for national surveillance and epidemiological research. Methods We used the Delphi process with internal (RKI) and external experts and a metric-consensus approach to score pathogens according to ten three-tiered criteria. Additional experts were invited to weight each criterion, leading to the calculation of a median weight by which each score was multiplied. We ranked the pathogens according to the total weighted score and divided them into four priority groups. Results 127 pathogens were scored. Eighty-six experts participated in the weighting; “Case fatality rate” was rated as the most important criterion. Twenty-six pathogens were ranked in the highest priority group; among those were pathogens with internationally recognised importance (e.g., Human Immunodeficiency Virus, Mycobacterium tuberculosis, Influenza virus, Hepatitis C virus, Neisseria meningitides), pathogens frequently causing large outbreaks (e.g., Campylobacter spp.), and nosocomial pathogens associated with antimicrobial resistance. Other pathogens in the highest priority group included Helicobacter pylori, Respiratory Syncytial Virus, Varicella zoster virus and Hantavirus. Discussion While several pathogens from the highest priority group already have a high profile in national and international health policy documents, high scores for other pathogens (e.g., Helicobacter pylori, Respiratory syncytial virus or Hantavirus) indicate a possible under-recognised importance within the current German public health framework. A process to strengthen respective surveillance systems and research has been started. The prioritization methodology has worked well; its modular structure makes it potentially useful for other settings.

Systematic literature analysis and review of targeted preventive measures to limit healthcare-associated infections by meticillin-resistant Staphylococcus aureus

Meticillin-resistant Staphylococcus aureus (MRSA) is a major cause of healthcare-associated infections in Europe. Many examples have demonstrated that the spread of MRSA within healthcare settings can be reduced by targeted infection control measures. The aim of this systematic literature analysis and review was to summarise the evidence for the use of bacterial cultures for active surveillance the benefit of rapid screening tests, as well as the use of decolonisation therapies and different types of isolation measures. We included 83 studies published between 2000 and 2012. Although the studies reported good evidence supporting the role of active surveillance followed by decolonisation therapy, the effectiveness of single-room isolation was mostly shown in non-controlled studies, which should inspire further research regarding this issue. Overall, this review highlighted that when planning the implementation of preventive interventions, there is a need to consider the prevalence of MRSA, the incidence of infections, the competing effect of standard control measures (e.g. hand hygiene) and the likelihood of transmission in the respective settings of implementation.

Successful Termination of a Furunculosis Outbreak Due to lukS-lukF–Positive, Methicillin-Susceptible Staphylococcus aureus in a German Village by Stringent Decolonization, 2002–2005

BACKGROUND Skin infections due to Staphylococcus aureus have recently become a public concern, mainly because of emerging resistance against widely used antibiotics and specific virulence determinants. Strains harboring the lukS-lukF gene (which codes for Panton-Valentine leukocidin) are frequently associated with severe furunculosis. Generally applicable strategies for the control of community outbreaks of furunculosis have not been defined. METHODS We report the investigation and successful termination of an outbreak of furunculosis due to lukS-lukF-positive S. aureus in a German village (n=144). Nasal swab specimens were obtained from village residents. A retrospective cohort study was conducted. Nasally colonized persons, persons who had current furuncles or who had experienced relapsing furuncles since 2002, and their family members underwent stringent decolonization measures using mupirocin nasal ointment and disinfecting wash solution. Multiple nasal swab specimens were obtained to monitor the long-term outcome of decolonization measures. RESULTS From January 1998 through December 2004, 42 cases and 59 relapses of furunculosis were identified by active case finding. Of 140 participants tested, 51 (36%) were found to be nasally colonized with S. aureus. In 9 participants, the strain was positive for lukS-lukF. No methicillin resistance was detected. Risk of furunculosis was associated with contact with case patients (relative risk, 6.8; 95% confidence interval, 3.2-14.3) and nasal colonization with a lukS-lukF-positive strain of S. aureus (relative risk, 3.6; 95% confidence interval, 2.3-5.9). Passive surveillance implemented in January 2005 did not detect any case of lukS-lukF-positive, S. aureus-associated furuncles in this village. CONCLUSION This report describes a successful strategy for terminating the transmission of epidemic strains of S. aureus among a nonhospitalized population.

Bartonella henselae-Specific Cell-Mediated Immune Responses Display a Predominantly Th1 Phenotype in Experimentally Infected C57BL/6 Mice

ABSTRACT Immune responses of the immunocompetent host to Bartonella henselae infection were investigated in the murine infection model using C57BL/6 mice. Following intraperitoneal infection with human-derived B. henselae strain Berlin-1, viable bacteria could be recovered from livers and spleens during the first week postinfection, while Bartonella DNA remained detectable by PCR in the liver for up to 12 weeks after infection. Granulomatous lesions developed in livers of infected mice, reached maximal density at 12 weeks after infection, and persisted for up to 20 weeks, indicating that B. henselae induced a chronic granulomatous hepatitis in the immunocompetent murine host. T-cell-mediated immune responses were analyzed in vitro by means of spleen cell proliferation and cytokine release assays as well as analysis of immunoglobulin G (IgG) isotypes. Spleen cells from infected mice proliferated specifically upon stimulation with heat-killedBartonella antigen. Proliferative responses were mainly mediated by CD4+ T cells, increased during the course of infection, peaked at 8 weeks postinfection, and decreased thereafter. Gamma interferon, but not interleukin-4, was produced in vitro by spleen cells from infected animals upon stimulation withBartonella antigens. Bartonella-specific IgG was detectable in serum of infected mice by 2 weeks, and the antibody concentration peaked at 12 weeks postinfection. IgG2b was the prominent isotype among the Bartonella-specific serum IgG antibodies. These data indicate that B. henselaeinduces cell-mediated immune responses with a Th1 phenotype in immunocompetent C57BL/6 mice.

Quantitative detection and biological propagation of scrapie seeding activity in vitro facilitate use of prions as model pathogens for disinfection.

Prions are pathogens with an unusually high tolerance to inactivation and constitute a complex challenge to the re-processing of surgical instruments. On the other hand, however, they provide an informative paradigm which has been exploited successfully for the development of novel broad-range disinfectants simultaneously active also against bacteria, viruses and fungi. Here we report on the development of a methodological platform that further facilitates the use of scrapie prions as model pathogens for disinfection. We used specifically adapted serial protein misfolding cyclic amplification (PMCA) for the quantitative detection, on steel wires providing model carriers for decontamination, of 263K scrapie seeding activity converting normal protease-sensitive into abnormal protease-resistant prion protein. Reference steel wires carrying defined amounts of scrapie infectivity were used for assay calibration, while scrapie-contaminated test steel wires were subjected to fifteen different procedures for disinfection that yielded scrapie titre reductions of ≤101- to ≥105.5-fold. As confirmed by titration in hamsters the residual scrapie infectivity on test wires could be reliably deduced for all examined disinfection procedures, from our quantitative seeding activity assay. Furthermore, we found that scrapie seeding activity present in 263K hamster brain homogenate or multiplied by PMCA of scrapie-contaminated steel wires both triggered accumulation of protease-resistant prion protein and was further propagated in a novel cell assay for 263K scrapie prions, i.e., cerebral glial cell cultures from hamsters. The findings from our PMCA- and glial cell culture assays revealed scrapie seeding activity as a biochemically and biologically replicative principle in vitro, with the former being quantitatively linked to prion infectivity detected on steel wires in vivo. When combined, our in vitro assays provide an alternative to titrations of biological scrapie infectivity in animals that substantially facilitates the use of prions as potentially highly indicative test agents in the search for novel broad-range disinfectants.

Prevention and control of nosocomial infections and resistance to antibiotics in Europe - Primum non-nocere: elements of successful prevention and control of healthcare-associated infections.

In October 2004, the WHO launched the World Alliance for Patient Safety. In 2006, the Council of Europe adopted a recommendation on the management of patient safety and prevention of adverse events in healthcare to acknowledge that patients can expect each EU health system to secure a systematic approach to ensuring patient safety. This review is a compilation of broadly accepted instruments for the prevention and control of healthcare-associated infections and resistance to antibiotics in Europe. Antibiotic-resistant bacteria do not stop at the exit of a hospital. The implementation of the various elements of a whole bundle of recommended prevention and control measures in the context of interacting healthcare institutions including long-term care, rehabilitation facilities, ambulatory care practices, and home care, is therefore facilitated by the establishment of regional networks and the integration of prevention and control strategies into disease management programmes. In order to increase efficiency of prevention and control measures, there is a need for the careful design of interventional studies to figure out the most efficient single or bundle of preventive measures. In addition, methods for the discovery of clusters on the basis of routinely obtained data should be improved.

Healthcare-associated infections in long-term care facilities (HALT)

The development of infections in elderly people living in long-term care facilities may have manifold causes. Infections are often treated with an antibiotic which can trigger the selection of multirestistant microorganisms and, therefore, represents an additional risk factor. In Germany as well as in other European countries, only a few prevalence studies on healthcare-associated infections (HCAI) in long-term care facilities have been performed and there is no continuous surveillance established for HCAI and antibiotic treatment. Therefore, the European prevalence study HALT (healthcare-associated infections in long-term care) was initiated to collect data of HCAI, antibiotic use, and the antibiotic resistance of microorganisms in long-term care facilities. From Germany, 73 institutions participated in the HALT project. The overall prevalence for an optional HCAI (at least one symptom) was 1.6 (CI 1.09-2.03) and for HCAI identified by the modified McGeer criteria 0.79 (CI 0.62-1.04). The overall prevalence for antibiotic use was 1.15 (CI 0.73-1.57). In the present paper, the German results of the HALT project are presented.

Delayed type hypersensitivity-associated disruption of splenic periarteriolar lymphatic sheaths coincides with temporary loss of IFN-γ production and impaired eradication of bacteria in Brucella abortus-infected mice

A major problem of infections with facultative intracellular bacteria is their chronic course. We comprehensively evaluated the host response in murine brucellosis to study mechanisms contributing to bacterial persistence in the presence of an established immune response. Evidence is presented that the decrease in eradication kinetics, reproducibly occurring 18 d after infection of mice with Brucella abortus S19, is related to a state of downregulation of defense mechanisms. This is not due to a Th1 to Th2 switch or prostaglandin-mediated suppression by macrophages but is most probably caused by a severe disruption of spleen morphology at the height of Brucella-induced delayed type hypersensitivity. This results in a profound depletion of both CD4(+) and CD8(+) T cells in periarteriolar lymphatic sheaths, a consecutive deleterious shift in the relation of permissive macrophages and protective lymphocytes and an impaired capacity of splenocytes to produce IFN-gamma in response to soluble Brucella antigen.

Fast, broad-range disinfection of bacteria, fungi, viruses and prions

Effective disinfectants are of key importance for the safe handling and reprocessing of surgical instruments. This study tested whether new formulations containing SDS, NaOH and 1-propanol (n-propanol) are simultaneously active against a broad range of pathogens including bacteria, fungi, non-enveloped viruses and prions. Inactivation and disinfection were examined in suspension and on carriers, using coagulated blood or brain homogenate as an organic contaminant. Coomassie blue staining was used to assess whether the formulations undesirably fixed proteins to rough surfaces. A mixture of 0.2 % SDS and 0.3 % NaOH in 20 % n-propanol achieved potent decontamination of steel carriers contaminated with PrP(TSE), the biochemical marker for prion infectivity, from 263K scrapie hamsters or from patients with sporadic or variant Creutzfeldt-Jakob disease. 263K scrapie infectivity on carriers was decreased by > or =5.5 logs. Furthermore, the formulation effectively inactivated poliovirus, hepatitis A virus and caliciviruses (including murine norovirus) in suspension tests. It also yielded significant titre reductions of bacteria (Enterococcus faecium, Mycobacterium avium; >6 logs), fungi (spores of Aspergillus niger; > or =5 logs) and poliovirus (>4 logs) embedded in coagulated blood on carriers. The formulation was not found to fix proteins more than was observed with water as the cleaning reagent. In conclusion, SDS, NaOH and n-propanol can synergistically achieve fast, broad-range disinfection.