European Journal of Microbiology & Immunology最新文献

Background: The study assessed a spectrum of previously published in-house fluorescence in-situ hybridization (FISH) probes in a combined approach regarding their diagnostic performance with incubated blood culture materials.

Methods: Within a two-year interval, positive blood culture materials were assessed with Gram and FISH staining. Previously described and new FISH probes were combined to panels for Gram-positive cocci in grape-like clusters and in chains, as well as for Gram-negative rod-shaped bacteria. Covered pathogens comprised Staphylococcus spp., such as S. aureus, Micrococcus spp., Enterococcus spp., including E. faecium, E. faecalis, and E. gallinarum, Streptococcus spp., like S. pyogenes, S. agalactiae, and S. pneumoniae, Enterobacteriaceae, such as Escherichia coli, Klebsiella pneumoniae and Salmonella spp., Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Bacteroides spp.

Results: A total of 955 blood culture materials were assessed with FISH. In 21 (2.2%) instances, FISH reaction led to non-interpretable results. With few exemptions, the tested FISH probes showed acceptable test characteristics even in the routine setting, with a sensitivity ranging from 28.6% (Bacteroides spp.) to 100% (6 probes) and a specificity of >95% in all instances.

Conclusion: If sophisticated rapid diagnostic methods like mass spectrometry from blood culture materials are not available, FISH provides an option for rapid differentiation for laboratories in resource-limited settings.

Extracellular deoxyribonucleases (DNases) contribute to the spread of pathogenic bacteria through the evasion from host innate immunity. Our main objective was to evaluate the production of extracellular DNases by human and bovine Streptococcus agalactiae clinical strains and perform a correlation of genetic lineages and DNase activity with capsular type, genetic determinants, clinical origin (colonization and infection), and host (human or bovine). DNase activity was evaluated by qualitative and quantitative assays for a collection of 406 human (n = 285) and bovine (n = 121) strains. All (121/121) bovine were isolated from mastitis and revealed to be DNase (+), indicating a putative pathogenic role in this clinical scenario. From the human S. agalactiae strains, 86% (245/285) showed DNase activity, among which all strains belonging to capsular types, namely, Ia, Ib, III-2, and IV. All CC17 strains (n = 58) and 56/96 (58.3%) of the CC19 displayed DNase activity. DNase (-) strains belonged to the CC19 group. However, the subcharacterization of CC19 S. agalactiae strains through multiple-locus variable number tandem repeat analysis (MLVA), antibiotic resistance, mobile elements, and surface proteins did not provide any distinction among DNase producers and non-producers. The production of DNases by all human CC17 strains, about two-fifths of human CC19, and all bovine strains, suggest an important contribution of DNases to hypervirulence.

In chronic obstructive pulmonary disease (COPD), acute exacerbations and emphysema development are characteristics for disease pathology. COPD is complicated by infectious exacerbations with acute worsening of respiratory symptoms with Moraxella catarrhalis as one of the most frequent pathogens. Although cigarette smoke (CS) is the primary risk factor, additional molecular mechanisms for emphysema development induced by bacterial infections are incompletely understood. We investigated the impact of M. catarrhalis on emphysema development in CS exposed mice and asked whether an additional infection would induce a solubilization of pro-apoptotic and pro-inflammatory endothelial monocyte-activating-protein-2 (EMAPII) to exert its activities in the pulmonary microvas-culature and other parts of the lungs not exposed directly to CS. Mice were exposed to smoke (6 or 9 months) and/or infected with M. catarrhalis. Lungs, bronchoalveolar lavage fluid (BALF), and plasma were analyzed. CS exposure reduced ciliated area, caused rarefaction of the lungs, and induced apoptosis. EMAPII was increased independent of prior smoke exposure in BALF of infected mice. Importantly, acute M. catarrhalis infection increased release of matrixmetalloproteases-9 and -12, which are involved in emphysema development and comprise a mechanism of EMAPII release. Our data suggest that acute M. catarrhalis infection represents an independent risk factor for emphysema development in smoke-exposed mice.

Photoinactivation of bacteria with visible light has been reported in numerous studies. Radiation around 405 nm is absorbed by endogenous porphyrins and generates reactive oxygen species that destroy bacteria from within. Blue light in the spectral range of 450-470 nm also exhibits an antibacterial effect, but it is weaker than 405 nm radiation, and the photosensitizers involved have not been clarified yet, even though flavins and porphyrins are possible candidates. There are significantly fewer photoinactivation studies on fungi. To test if visible light can inactivate fungi and to elucidate the mechanisms involved, the model organism Saccharomyces cerevisiae (DSM no. 70449) was irradiated with violet (405 nm) and blue (450 nm) light. The mean irradiation doses required for a one log reduction of colony forming units for this strain were 182 J/cm² and 526 J/cm² for 405 nm and 450 nm irradiation, respectively. To investigate the cell damaging mechanisms, trypan blue staining was performed. However, even strongly irradiated cultures hardly showed any stained S. cerevisiae cells, indicating an intact cell membrane and thus arguing against the previously suspected mechanism of cell membrane damage during photoinactivation with visible light at least for the investigated strain. The results are compatible with photoinactivated Saccharomyces cerevisiae cells being in a viable but nonculturable state. To identify potential fungal photosensitizers, the absorption and fluorescence of Saccharomyces cerevisiae cell lysates were determined. The spectral absorption and fluorescence results are in favor of protoporphyrin IX as the most important photosensitizer at 405 nm radiation. For 450 nm irradiation, riboflavin and other flavins may be the main photosensitizer candidates, since porphyrins do not play a prominent role at this wavelength. No evidence of the involvement of other photosensitizers was found in the spectral data of this strain.

Adaptive immunity is essentially required to control acute infection with enteropathogenic Yersinia pseudotuberculosis (Yptb). We have recently demonstrated that Yptb can directly modulate naïve CD4⁺ T cell differentiation. However, whether fully differentiated forkhead box protein P3 (Foxp3⁺) regulatory T cells (Tregs), fundamental key players to maintain immune homeostasis, are targeted by Yptb remains elusive. Here, we demonstrate that within the CD4⁺ T cell compartment Yptb preferentially targets Tregs and injects Yersinia outer proteins (Yops) in a process that depends on the type III secretion system and invasins. Remarkably, Yop-translocation into ex vivo isolated Foxp3⁺ Tregs resulted in a substantial downregulation of Foxp3 expression and a decreased capacity to express the immunosuppressive cytokine interleukin-10 (IL-10). Together, these findings highlight that invasins are critically required to mediate Yptb attachment to Foxp3⁺ Tregs, which allows efficient Yop-translocation and finally enables the modulation of the Foxp3⁺ Tregs' suppressive phenotype.

Introduction: To prevent surgical site infections (SSIs) during operation, the use of sterile surgical latex gloves is common. The aim of this study was to examine the damage of the gloves in surgeries with different mechanical stress and the influence on the kind of damages. Gloves were collected during primary arthroplasty, revision arthroplasty (hip and knee), and arthroscopy (shoulder, hip, and knee).

Materials and methods: Surgical latex operation gloves were collected from surgeons after the operation and were tested with watertightness test (ISO EN 455-1:2000).

Results: A total of 1460 surgical gloves were retrieved from 305 elective operations. On average, 15.9% of the gloves showed postoperative lesions, with the highest incidence occurring in revision arthroplasty with 25%. In primary and revision arthroplasty, the index finger of the dominant hand was most frequently affected (62.7% and 58.6%); in contrast, gloves from arthroscopies had most lesions on thumb and middle finger (42.9% each). Tear and perforation size differed from ≤1 mm to >5 mm, and primary and revision arthroplasty showed bigger damages.

Conclusions: Surgical gloves have a high malfunction, which increases with growing mechanical stress. A high rate of perforation occurred mostly in revision arthroplasty. Breaching the integrity of the gloves, especially by high mechanical loads, could lead to an increased rate of infection.

We determined the association between having a history of surgery and the seroreactivity to T. gondii. An age- and gender-matched case-control study of 391 subjects with a history of surgery and 391 subjects without this history was performed. Sera of subjects were analyzed for detection of anti-T. gondii immunoglobulin G (IgG) and M (IgM) antibodies using enzyme-linked immunoassays. Anti-T. gondii IgG antibodies were found in 25 (6.4%) of the 391 cases and in 21 (5.4%) of the 391 controls (odds ratio [OR] = 1.29; 95% confidence interval [CI]: 0.66-2.18; P = 0.54). The frequency of cases with high IgG antibody levels (10/25: 40.0%) was equal to that found in controls (8/21: 38.1%) (OR = 1.08; 95% CI: 0.32-3.56; P = 0.89). Of the 25 anti-T. gondii IgG antibody seropositive cases, 5 (16.0%) were also positive for anti-T. gondii IgM antibodies. Meanwhile, of the 21 anti-T. gondii IgG antibody seropositive controls, 4 (19.0%) were also positive for anti-T gondii IgM antibodies (OR = 0.81; 95% CI: 0.17-3.72; P = 0.80). Logistic regression showed that only the variable "hysterectomy" was associated with T. gondii seropositivity (OR = 4.6; 95% CI: 1.6-13.4; P = 0.005). Results suggest that having a history of surgery is not an important risk factor for infection with T. gondii. However, the link between T. gondii infection and hysterectomy should be further investigated.

Background: The objective of this study was to assess an in-house loop-mediated isothermal amplification (LAMP) platform for malaria parasite detection and identification on species level.

Methods: LAMP primers specific for the human Plasmodium spp., namely, P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi, as well as genus-specific primers, were tested against a composite gold standard comprising microscopy from thick and thin blood films, commercial genus-specific Meridian illumigene Malaria LAMP, in-house real-time polymerase chain reaction (PCR), and commercial fast-track diagnostics (FTD) Malaria differentiation PCR.

Results: Of the 523 blood samples analyzed, the composite gold standard indicated 243 Plasmodium-species-DNA-containing samples (46.5%). Sensitivity and specificity of the analyzed genus- and species-specific LAMP primers were 71.0%-100.0% and 90.8%-100.0%, respectively. The influence of parasitemia was best documented for P. falciparum-specific LAMP with sensitivity values of 35.5% (22/62) for microscopically negative samples containing P. falciparum DNA, 50% (19/38) for parasitemia ≤50/μL, 84% (21/25) for parasitemia ≤500/μL, and 100% (92/92) for parasitemia >500/μL.

Conclusions: In our hands, performance characteristics of species-specific in-house LAMP for malaria lack reliability required for diagnostic laboratories. The use of the easy-to-apply technique for surveillance purposes may be considered.

Background: The effects of cell-free culture supernatants of probiotic Lactobacillus rhamnosus GG and Streptococcus salivarius K12 on replication and biofilm forming of Staphylococcus aureus and S. epidermidis were assessed in vitro.

Methods: S. aureus and S. epidermidis strains were exposed to cell-free culture supernatants of L. rhamnosus GG and S. salivarius K12 at different concentrations starting at 0, 4, and 24 h after the onset of incubation. Bacterial amplification was measured on microplate readers, as well as biofilm growth after safranine staining. Scanning electron microscopy was performed for visualization of biofilm status.

Results: The S. salivarius K12 culture supernatant not only reduced or prevented the formation and maturation of fresh biofilms but even caused a reduction of preformed S. epidermidis biofilms. The L. rhamnosus GG culture supernatant did not show clear inhibitory effects regardless of concentration or time of addition of supernatant, and even concentration-depending promotional effects on the planktonic and biofilm growth of S. aureus and S. epidermidis were observed.

Conclusion: In particular, the inhibitory effects of the S. salivarius K12 culture supernatant on the formation of staphylococcal biofilms are of potential relevance for biofilm-associated diseases and should be further assessed by in vivo infection models.

The fever-inducing effect of lipopolysaccharides (LPS) is well known, and human blood is extremely responsive to this pyrogen. Recently, the safety of LPS-containing food supplements and probiotic drugs as immune-stimulants has been questioned, although these products are orally taken and do not reach the bloodstream undigested. The concerns are understandable, as endotoxaemia is a pathological condition, but the oral uptake of probiotic products containing LPS or Gram-negative bacteria does not pose a health risk, based on the available scientific evidence, as is reviewed here. The available methods developed to detect LPS and other pyrogens are mostly used for quality control of parentally applied therapeuticals. Their outcome varies considerably when applied to food supplements, as demonstrated in a simple comparative experiment. Products containing different Escherichia coli strains can result in vastly different results on their LPS content, depending on the method of testing. This is an inherent complication to pyrogen testing, which hampers the communication that the LPS content of food supplements is not a safety concern.