Fluorescence in situ hybridization (FISH) in the microbiological diagnostic routine laboratory: a review

Early identification of microbial pathogens is essential for rational and conservative antibiotic use especially in the case of known regional resistance patterns. Here, we describe fluorescence in situ hybridization (FISH) as one of the rapid methods for easy identification of microbial pathogens, and its advantages and disadvantages for the diagnosis of pathogens in human infections in the laboratory diagnostic routine. Binding of short fluorescence-labeled DNA or nucleic acid-mimicking PNA probes to ribosomes of infectious agents with consecutive analysis by fluorescence microscopy allows identification of bacterial and eukaryotic pathogens at genus or species level. FISH analysis leads to immediate differentiation of infectious agents without delay due to the need for microbial culture. As a microscopic technique, FISH has the unique potential to provide information about spatial resolution, morphology and identification of key pathogens in mixed species samples. On-going automation and commercialization of the FISH procedure has led to significant shortening of the time-to-result and increased test reliability. FISH is a useful tool for the rapid initial identification of microbial pathogens, even from primary materials. Among the rapidly developing alternative techniques, FISH serves as a bridging technology between microscopy, microbial culture, biochemical identification and molecular diagnostic procedures.

Heparan sulfates and coxsackievirus-adenovirus receptor: each one mediates coxsackievirus B3 PD infection

Amino acid exchanges in the virus capsid protein VP1 allow the coxsackievirus B3 variant PD (CVB3 PD) to replicate in decay accelerating factor (DAF)-negative and coxsackievirus-adenovirus receptor (CAR)-negative cells. This suggests that molecules other than DAF and CAR are involved in attachment of this CVB3 variant to cell surfaces. The observation that productive infection associated with cytopathic effect occurred in Chinese hamster ovary (CHO-K1) cells, whereas heparinase-treated CHO-K1 cells, glucosaminoglycan-negative pgsA-745, heparan sulfate (HS)-negative pgsD-677, and pgsE-606 cells with significantly reduced N-sulfate expression resist CVB3 PD infection, indicates a critical role of highly sulfated HS. 2-O-sulfate-lacking pgsF-17 cells represented the cell line with minimum HS modifications susceptible for CVB3 PD. Inhibition of virus replication in CHO-K1 cells by polycationic compounds, pentosan polysulfate, lung heparin, and several intestinal but not kidney HS supported the hypothesis that CVB3 PD uses specific modified HS for entry. In addition, recombinant human hepatocyte growth factor blocked CVB3 PD infection. However, CAR also mediates CVB3 PD infection, because this CVB3 variant replicates in HS-lacking but CAR-bearing Raji cells, infection could be prevented by pretreatment of cells with CAR antibody, and HS-negative pgsD-677 cells transfected with CAR became susceptible for CVB3 PD. These results demonstrate that the amino acid substitutions in the viral capsid protein VP1 enable CVB3 PD to use specific modified HS as an entry receptor in addition to CAR.

Discrimination of multilocus sequence typing-based Campylobacter jejuni subgroups by MALDI-TOF mass spectrometry

Background

Campylobacter jejuni, the most common bacterial pathogen causing gastroenteritis, shows a wide genetic diversity. Previously, we demonstrated by the combination of multi locus sequence typing (MLST)-based UPGMA-clustering and analysis of 16 genetic markers that twelve different C. jejuni subgroups can be distinguished. Among these are two prominent subgroups. The first subgroup contains the majority of hyperinvasive strains and is characterized by a dimeric form of the chemotaxis-receptor Tlp7_m+c. The second has an extended amino acid metabolism and is characterized by the presence of a periplasmic asparaginase (ansB) and gamma-glutamyl-transpeptidase (ggt).

Results

Phyloproteomic principal component analysis (PCA) hierarchical clustering of MALDI-TOF based intact cell mass spectrometry (ICMS) spectra was able to group particular C. jejuni subgroups of phylogenetic related isolates in distinct clusters. Especially the aforementioned Tlp7_m+c⁺ and ansB⁺/ ggt⁺ subgroups could be discriminated by PCA. Overlay of ICMS spectra of all isolates led to the identification of characteristic biomarker ions for these specific C. jejuni subgroups. Thus, mass peak shifts can be used to identify the C. jejuni subgroup with an extended amino acid metabolism.

Conclusions

Although the PCA hierarchical clustering of ICMS-spectra groups the tested isolates into a different order as compared to MLST-based UPGMA-clustering, the isolates of the indicator-groups form predominantly coherent clusters. These clusters reflect phenotypic aspects better than phylogenetic clustering, indicating that the genes corresponding to the biomarker ions are phylogenetically coupled to the tested marker genes. Thus, PCA clustering could be an additional tool for analyzing the relatedness of bacterial isolates.

Chemotaxis in Campylobacter jejuni

Chemotaxis is the common way of flagellated bacteria to direct their locomotion to sites of most favourable living conditions, that are sites with the highest concentrations of energy sources and the lowest amounts of bacteriotoxic substances. The general prerequisites for chemotaxis are chemoreceptors, a chemosensory signal-transduction system and the flagellar apparatus. Epsilonproteobacteria like Campylobacter sp. show specific variations of the common chemotaxis components. CheV, a CheW-like linking-protein with an additional response regulator (RR) domain, was identified as commonly used coupling scaffold protein of Campylobacter jejuni. It attaches the histidine autokinase (CheAY), which also has an additional RR-domain, to the chemoreceptors signalling domains. These additional RR-domains seem to play an important role in the regulation of the CheAY-phosphorylation state and thereby in sensory adaptation. The Campylobacter-chemoreceptors are arranged into the three groups A, B, and C. Group A contains membrane-anchored receptors sensing periplasmic signals, group B consists only of one receptor with two cytoplasmic ligand-proteins representing a bipartite energy taxis system that senses pyruvate and fumarate, and group C receptors are cytoplasmic signalling domains with mostly unknown cytoplasmic ligand-binding proteins as sensory constituents. Recent findings demonstrating different alleles of the TLP7 chemoreceptor, specific for formic acid, led to an amendment of this grouping.

On detection thresholds-a review on diagnostic approaches in the infectious disease laboratory and the interpretation of their results

Diagnostic testing in the infectious disease laboratory facilitates decision-making by physicians at the bedside as well as epidemiological assessments and surveillance at study level. Problems may arise if test results are uncritically considered as being the same as the unknown true value. To allow a better understanding, the influence of external factors on the interpretation of test results is introduced with the example of prevalence, followed by the presentation of strengths and weaknesses of important techniques in the infectious disease laboratory like microscopy, cultural diagnostics, serology, mass spectrometry, nucleic acid amplification and hypothesis-free metagenomic sequencing with focus on basic, high-technology and potential future approaches. Special problems like multiplex testing as well as uncertainty of test evaluations, if no gold standard is available, are also stressed with a final glimpse on emerging future technologies for the infectious disease laboratory. In the conclusions, suitability for point-of-care-testing and field laboratory applications is summarized. The aim is to illustrate the limitations of diagnostic accuracy to both clinicians and study planners and to stress the importance of close cooperation with experts in laboratory disciplines so as to avoid potentially critical misunderstandings due to inappropriate interpretation of diagnostic test results.

Mass Spectrometry-based PhyloProteomics (MSPP): A novel microbial typing Method

MALDI-TOF-MS of microorganisms, which identifies microbes based on masses of high abundant low molecular weight proteins, is rapidly advancing to become another standard method in clinical routine laboratory diagnostics. Allelic isoforms of these proteins result in varying masses of detectable biomarker ions. These variations give rise to a novel typing method for microorganisms named mass spectrometry-based phyloproteomics (MSPP). The base of MSPP is an amino acid sequence list of allelic isoforms caused by non-synonymous mutations in biomarker genes, which were detectable as mass shifts in an overlay of calibrated MALDI-TOF spectra. Thus, for each isolate a combination of amino acid sequences can be deduced from the scheme of recordable biomarker masses. Performing comparably to laborious multilocus and whole genome sequence typing (wgMLST)-approaches it is feasible to build phyloproteomic dendrograms using hierarchical cluster analysis. MSPP bears a high potential especially for identification of chromosomal localised virulence or antimicrobial resistance factors associated with evolutionary relatedness. In this study the principle of MSPP-typing was demonstrated on a Campylobacter jejuni ssp. jejuni isolate collection and MSPP was compared to MLST.

Microbiological laboratory diagnostics of neglected zoonotic diseases (NZDs)

This review reports on laboratory diagnostic approaches for selected, highly pathogenic neglected zoonotic diseases, i.e. anthrax, bovine tuberculosis, brucellosis, echinococcosis, leishmaniasis, rabies, Taenia solium-associated diseases (neuro-/cysticercosis & taeniasis) and trypanosomiasis. Diagnostic options, including microscopy, culture, matrix-assisted laser-desorption-ionisation time-of-flight mass spectrometry, molecular approaches and serology are introduced. These procedures are critically discussed regarding their diagnostic reliability and state of evaluation. For rare diseases reliable evaluation data are scarce due to the rarity of samples. If bio-safety level 3 is required for cultural growth, but such high standards of laboratory infrastructure are not available, serological and molecular approaches from inactivated sample material might be alternatives. Multiple subsequent testing using various test platforms in a stepwise approach may improve sensitivity and specificity. Cheap and easy to use tests, usually called "rapid diagnostic tests" (RDTs) may impact disease control measures, but should not preclude developing countries from state of the art diagnostics.

[Campylobacteriosis of man : livestock as reservoir for Campylobacter species]

Over the last few years, infections with Campylobacter have significantly increased in Europe and Germany and these bacteria have even surpassed Salmonella as the most prevalent bacteria, causing gastroenteritis. Especially contamination during the handling and consumption of meat products seems to be the most important risk factor which plays a prominent role for transmission to man. In addition, contact with pets and other animals, drinking raw or improperly pasteurized milk, and the tenacity of Campylobacter in different environments, especially water, have also to be considered for an adequate risk assessment. Besides gastroenteritis, arthralgia, and Guillain-Barré syndrome are important clinical complications of Campylobacter infections in man. At the same time, it is mostly unclear why the course of infection in man and in reservoir animals differs significantly, especially as only a few classical bacterial virulence factors have been identified so far. For these reasons, the development of efficient prevention strategies is of utmost importance in order to control campylobacteriosis.

Spectrum of viral infections in patients with cystic fibrosis

This review explores the extensive influence of viral infections leading to chronic deterioration of lung function in patients with cystic fibrosis (CF). The mechanisms how viral agents affect the pathogenesis as well as the inflammatory and immune response of CF are discussed. Viral infections of the upper and lower respiratory tract due to viruses in CF patients and methods for diagnosis of respiratory viruses are described in detail. The importance of respiratory and non-respiratory viral agents for the pathogenesis, especially for the exacerbation of bacterial lower respiratory tract infections and course of CF, is stressed, especially emphasizing respiratory syncytial virus, influenza virus, rhinovirus, and human herpes viruses. Possible harmful effects of further viruses like adenovirus, bocavirus, coronavirus, metapneumovirus, parainfluenzavirus on the lung function of CF patients are discussed. The potential use of adenovirus-based vectors for somatic gene therapy is mentioned.

The influence of virus infections on the course of COPD

Chronic obstructive pulmonary disease (COPD) is extensively influenced by viral infections. The mechanisms of how viral agents affect the pathogenesis and prognosis of COPD are numerous. In general, patients with infectious exacerbations are characterized by longer hospitalization periods and greater impairment of several lung function parameters than those with non-infectious exacerbations. Prodromal, clinical, and outcome parameters fail to distinguish virally from non-virally induced illnesses in cases of exacerbations. The importance of infections with respiratory and non-respiratory viral agents for pathogenesis and course of COPD is detailed. Human adenovirus, non-respiratory viruses including human immunodeficiency virus, human metapneumovirus, influenza virus, human rhinovirus, and respiratory syncytial virus are especially stressed.

Proteotyping as alternate typing method to differentiate Campylobacter coli clades

Besides Campylobacter jejuni, Campylobacter coli is the most common bacterial cause of gastroenteritis worldwide. C. coli is subdivided into three clades, which are associated with sample source. Clade 1 isolates are associated with acute diarrhea in humans whereas clade 2 and 3 isolates are more commonly obtained from environmental waters. The phylogenetic classification of an isolate is commonly done using laborious multilocus sequence typing (MLST). The aim of this study was to establish a proteotyping scheme using MALDI-TOF MS to offer an alternative to sequence-based methods. A total of 97 clade-representative C. coli isolates were analyzed by MALDI-TOF-based intact cell mass spectrometry (ICMS) and evaluated to establish a C. coli proteotyping scheme. MLST was used as reference method. Different isoforms of the detectable biomarkers, resulting in biomarker mass shifts, were associated with their amino acid sequences and included into the C. coli proteotyping scheme. In total, we identified 16 biomarkers to differentiate C. coli into the three clades and three additional sub-clades of clade 1. In this study, proteotyping has been successfully adapted to C. coli. The established C. coli clades and sub-clades can be discriminated using this method. Especially the clinically relevant clade 1 isolates can be differentiated clearly.

The viral genetic background determines the outcome of coxsackievirus B3 infection in outbred NMRI mice

The reasons for the different outcome of coxsackievirus B3 (CVB3)-induced heart disease in humans are not well understood. Since there are no experimental data on the course of disease after infection with genetically different CVB3 in a natural variable population until now, we studied the outcome of virus infection in outbred NMRI mice after inoculation of genetically different CVB3 variants. Adult male mice were inoculated with seven closely related CVB3 variants. The histopathological changes of heart and pancreas tissue, antibody induction, virus titers, and persistence of viral positive- as well as negative-strand RNA in spleen and heart tissue were compared at day 7 or day 28 after infection to detect prerequisites and predictive factors for chronic myocarditis. Six CVB3 variants infected NMRI mice. CVB3 infection (i) did not induce detectable myocardial injury, (ii) caused signs of healing up acute myocarditis or (iii) ongoing chronic myocarditis. Neither IgG antibody responses nor the extent of destruction of exocrine pancreatic tissue or viral RNA load in spleen did correlate with myocardial histopathology. In contrast, a high persistent viral RNA load in heart tissue specimens was characteristic for mice developing chronic myocarditis. The results of the present study corroborate high viral load in the acute stage of myocarditis and high amounts of persisting CVB3 RNA in heart tissue as predictive marker of chronic myocarditis. The outcome of CVB3-induced heart disease in outbred NMRI mice depends strongly on the viral genetic background. In particular an important role of viral capsid proteins is suggested.

Diagnosing SARS-CoV-2 with Antigen Testing, Transcription-Mediated Amplification and Real-Time PCR

This study was performed as a head-to-head comparison of the performance characteristics of (1) two SARS-CoV-2-specific rapid antigen assays with real-time PCR as gold standard as well as (2) a fully automated high-throughput transcription-mediated amplification (TMA) assay and real-time PCR in a latent class analysis-based test comparison without a gold standard with several hundred samples in a low prevalence "real world" setting. Recorded sensitivity and specificity of the NADAL and the LumiraDx antigen assays and the Hologic Aptima SARS-CoV-2 TMA assay were 0.1429 (0.0194, 0.5835), 0.7644 (0.7016, 0.8174), and 0.7157 (0, 1) as well as 0.4545 (0.2022, 0.7326), 0.9954 (0.9817, 0.9988), and 0.9997 (not estimable), respectively. Agreement kappa between the positive results of the two antigen-based assays was 0.060 (0.002, 0.167) and 0.659 (0.492, 0.825) for TMA and real-time PCR. Samples with low viral load as indicated by cycle threshold (Ct) values > 30 were generally missed by both antigen assays, while 1:10 pooling suggested higher sensitivity of TMA compared to real-time PCR. In conclusion, both sensitivity and specificity speak in favor of the use of the LumiraDx rather than the NADAL antigen assay, while TMA results are comparably as accurate as PCR, when applied in a low prevalence setting.

Difficulties in species identification within the genus Haemophilus - A pilot study addressing a significant problem for routine diagnostics

Diagnostic misidentifications of commensalic Haemophilus haemolyticus as pathogenic Haemophilus influenzae are frequent. This pilot study evaluates whether isolations of H. haemolyticus are frequent enough in Germany to cause a relevant diagnostic problem, considering the fact that even H. influenzae is a mere colonizer in about 30% of isolations. In microbiological laboratories of two hospitals located in Northern and Southern Germany, the distribution of Haemophilus spp. was analyzed during a six-month-period. Site of infection, sex, and age of the patients was taken into consideration. A total of 77 Haemophilus spp. isolates was acquired and discriminated on species level, comprising: 48 H. influenzae, 25 Haemophilus parainfluenzae, 3 H. haemolyticus, and 1 Haemophilus parahaemolyticus. The proportion of H. haemolyticus was calculated to range between 1.2% and 16.2 % within the 95% confidence limits. Commensalic Haemophilus spp. were isolated from oropharynx-associated sites only. H. influenzae, in contrast, was detected in clinically relevant materials like lower respiratory materials and conjunctiva swabs. Altogether, there was a low proportion of clinical H. haemolyticus isolates. Accordingly, the problem of unnecessary antibiotic therapies due to misidentifications of H. haemolyticus as H. influenzae is quantitatively negligible compared with the risk of confusing H. influenzae colonizations with infections.

Effects of high hydrostatic pressure on bacterial growth on human ossicles explanted from cholesteatoma patients

BACKGROUND

High hydrostatic pressure (HHP) treatment can eliminate cholesteatoma cells from explanted human ossicles prior to re-insertion. We analyzed the effects of HHP treatment on the microbial flora on ossicles and on the planktonic and biofilm states of selected isolates.

METHODOLOGY

Twenty-six ossicles were explanted from cholesteatoma patients. Five ossicles were directly analyzed for microbial growth without further treatment. Fifteen ossicles were cut into two pieces. One piece was exposed to HHP of 350 MPa for 10 minutes. Both the treated and untreated (control) pieces were then assessed semi-quantitatively. Three ossicles were cut into two pieces and exposed to identical pressure conditions with or without the addition of one of two different combinations of antibiotics to the medium. Differential effects of 10-minute in vitro exposure of planktonic and biofilm bacteria to pressures of 100 MPa, 250 MPa, 400 MPa and 540 MPa in isotonic and hypotonic media were analyzed using two patient isolates of Staphylococcus epidermidis and Neisseria subflava. Bacterial cell inactivation and biofilm destruction were assessed by colony counting and electron microscopy.

PRINCIPAL FINDINGS

A variety of microorganisms were isolated from the ossicles. Irrespective of the medium, HHP treatment at 350 MPa for 10 minutes led to satisfying but incomplete inactivation especially of gram-negative bacteria. The addition of antibiotics increased the efficacy of elimination. A comparison of HHP treatment of planktonic and biofilm cells showed that the effects of HPP were reduced by about one decadic logarithmic unit when HPP was applied to biofilms. High hydrostatic pressure conditions that are suitable to inactivate cholesteatoma cells fail to completely sterilize ossicles even if antibiotics are added. As a result of the reduced microbial load and the viability loss of surviving bacteria, however, there is a lower risk of re-infection after re-insertion.

Subcutaneous fistulae in a patient with femoral hypoplasia due to Actinomyces europaeus and Actinomyces turicensis

Infections due to Actinomyces europaeus or Actinomyces turicensis have only rarely been reported. We describe a case of chronic fistulae caused by a coinfection with A. europaeus and A. turicensis in an immunocompetent male patient with a severe congenital femur hypoplasia. Actinomycosis is most probably the consequence of a postoperative wound infection after a prior surgical intervention. Both Actinomyces species were identified by 16S rRNA gene sequencing. The Actinomyces-caused fistulae were treated by excision and a 1-week course of i.v. vancomycin followed by a 1-week course of p.o. cefuroxime.

Towards proteomic species barcoding of fungi - An example using Scedosporium/Pseudallescheria complex isolates

MALDI-ToF mass spectrometry offers fast and reliable species identification for bacteria and yeasts under clinical routine conditions. Here, we produced mass spectra for identification of clinically important species of the Pseudallescheria/Scedosporium complex using the recently suggested new nomenclature and use this example to discuss to what extent the principle of DNA barcoding might be transferred to mass spectrometry.

Preoperative model for end-stage liver disease score as a predictor for posthemihepatectomy complications

BACKGROUND

As diagnostic techniques advance and surgical outcomes improve, the rate of utilization of liver hemihepatectomy for various indications will continue to increase.

OBJECTIVES

To explore the preoperative predictors of liver hemihepatectomy postoperative complications.

PATIENTS AND METHODS

This study included retrospective analysis of the clinical data of patients who underwent either liver hemihepatectomy or extended hemihepatectomy at Georg August University Hospital-Goettingen for the period 2002-2012. The outcomes were either postoperative complications or death of the patient (within 3 months from the end of the operation). Modified classification of surgical complications was adopted in the current study. The preoperative model for end-stage liver disease (MELD) score, aspartate aminotransferase, creatinine, international normalized ratio, and bilirubin in addition to the demographic characteristics of the patients and intraoperative blood loss were analyzed as predictive for postliver hemihepatectomy complications.

RESULTS

The study included 144 patients who underwent liver hemiheptectomy or extended hemihepatectomy through the study period (2002-2012). Postoperative complications were reported among patients out of 144 (52.1%). The most frequent complications were pleural effusion (26.7%), biliary leakage (21.3%), wound dehiscence (13.3%), ascites, and intra-abdominal abscess (6.7%). Death was reported among six patients of those who developed complications (8%). There were four cases of hepatic cirrhosis (one macroscopic and three microscopic). Two of the microscopic cases had no postoperative complications (grade 1), whereas one case had grade 3a and the macroscopic case had postoperative complication grade 1. Their MELD scores ranged between 6 and 10 preoperatively. The association between preoperative MELD score and development of posthemihepatetomy was statistically significant, P=0.002. Death was reported in six cases, yielding a mortality rate of 4.17%. MELD score preoperatively was the only significant predictor for postoperative complications.

CONCLUSION

The rate of complications following hemihepatectomy remains high, with 52.1% of the patients in the current study having at least one complication as all of our patients underwent either hemihepatectomy or extended hemihepatectomy. A 4.17% mortality rate has been reported. A higher preoperative MELD score is the only significant predictor for the development of posthemihepatectomy complications.

Case Report: Interferon- γ Rescues Monocytic Human Leukocyte Antigen Receptor (mHLA-DR) Function in a COVID-19 Patient With ARDS and Superinfection With Multiple MDR 4MRGN Bacterial Strains

Background

CD14+ monocytes present antigens to adaptive immune cells via monocytic human leukocyte antigen receptor (mHLA-DR), which is described as an immunological synapse. Reduced levels of mHLA-DR can display an acquired immune defect, which is often found in sepsis and predisposes for secondary infections and fatal outcomes. Monocytic HLA-DR expression is reliably induced by interferon- γ (IFNγ) therapy.

Case Report

We report a case of multidrug-resistant superinfected COVID-19 acute respiratory distress syndrome (ARDS) on extracorporeal membrane oxygenation (ECMO) support. The resistance profiles of the detected Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Citrobacter freundii isolates were equipped with resistance to all four antibiotic classes including carbapenems (4MRGN) and Cefiderocol in the case of K. pneumoniae. A causal therapeutic antibiotic strategy was not available. Therefore, we measured the immune status of the patient aiming to identify a potential acquired immune deficiency. Monocyte HLA-DR expression identified by FACS analysis revealed an expression level of 34% positive monocytes and suggested severe immunosuppression. We indicated IFNγ therapy, which resulted in a rapid increase in mHLA-DR expression (96%), rapid resolution of invasive bloodstream infection, and discharge from the hospital on day 70.

Discussion

Superinfection is a dangerous complication of COVID-19 pneumonia, and sepsis-induced immunosuppression is a risk factor for it. Immunosuppression is expressed by a disturbed antigen presentation of monocytes to cells of the adaptive immune system. The case presented here is remarkable as no validated antibiotic regimen existed against the detected bacterial pathogens causing bloodstream infection and severe pneumonia in a patient suffering from COVID-19 ARDS. Possible restoration of the patient's own immunity by IFNγ was a plausible option to boost the patient's immune system, eliminate the identified 4MRGNs, and allow for lung recovery. This led to the conclusion that immune status monitoring is useful in complicated COVID-19-ARDS and that concomitant IFNγ therapy may support antibiotic strategies.

Conclusion

After a compromised immune system has been detected by suppressed mHLA-DR levels, the immune system can be safely reactivated by IFNγ.

Difficult identification of Haemophilus influenzae, a typical cause of upper respiratory tract infections, in the microbiological diagnostic routine

Haemophilus influenzae is a key pathogen of upper respiratory tract infections. Its reliable discrimination from nonpathogenic Haemophilus spp. is necessary because merely colonizing bacteria are frequent at primarily unsterile sites. Due to close phylogenetic relationship, it is not easy to discriminate H. influenzae from the colonizer Haemophilus haemolyticus. The frequency of H. haemolyticus isolations depends on factors like sampling site, patient condition, and geographic region. Biochemical discrimination has been shown to be nonreliable. Multiplex PCR including marker genes like sodC, fucK, and hpd or sequencing of the 16S rRNA gene, the P6 gene, or multilocus-sequence-typing is more promising. For the diagnostic routine, such techniques are too expensive and laborious. If available, matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry is a routine-compatible option and should be used in the first line. However, the used database should contain well-defined reference spectra, and the spectral difference between H. influenzae and H. haemolyticus is small. Fluorescence in-situ hybridization is an option for less well-equipped laboratories, but the available protocol will not lead to conclusive results in all instances. It can be used as a second line approach. Occasional ambiguous results have to be resolved by alternative molecular methods like 16S rRNA gene sequencing.

Effects of easy-to-perform procedures to reduce bacterial colonization with Streptococcus mutans and Staphylococcus aureus on toothbrushes

It is well known that dental caries and periodontitis are the consequence of bacterial colonization and biofilm formation on the enamel surface. The continuous presence of bacterial biofilms on the tooth surface results in demineralization of the tooth enamel and induces an inflammatory reaction of the surrounding gums (gingivitis). The retention and survival of microorganisms on toothbrushes pose a threat of recontamination especially for certain patients at risk for systemic infections originating from the oral cavity, e.g., after T-cell depleted bone marrow transplantation. Thus, the effects of different decolonization schemes on bacterial colonization of toothbrushes were analyzed, in order to demonstrate their applicability to reduce the likelihood of (auto-)reinfections. Toothbrushes were intentionally contaminated with standardized suspensions of Streptococcus mutans or Staphylococcus aureus. Afterwards, the toothbrushes were exposed to rinsing under distilled water, rinsing and drying for 24 h, 0.2% chlorhexidine-based decolonization, or ultraviolet (UV) radiation. The remaining colony forming units were compared with freshly contaminated positive controls. Each experiment was nine-fold repeated. Bi-factorial variance analysis was performed; significance was accepted at P < 0.05. All tested procedures led to a significant reduction of bacteral colonization irrespective of the toothbrush model, the brush head type, or the acitivity state. Chlorhexidine-based decolonization was shown to be superior to rinsing and slightly superior to rinsing and drying for 24 h, while UV radiation was similarly effective as chlorhexidine. UV radiation was slightly less prone to species-dependent limitations of its decolonizing effects by bristle thickness of toothbrushes than chlorhexidin. Reduction of bacterial colonization of toothbrushes might reduce the risk of maintaining bacterial infections of the upper respiratory tract. Accordingly, respective procedures are advisable, particularly as they are cheap and easy to perform.

Is the Campylobacter jejuni secretory protein Cj0069 a suitable antigen for serodiagnostics?

Campylobacter spp. is the most common bacterial pathogen of gastroenteritis worldwide. Poultry is the main reservoir and consequently the main origin of infections for humans. As a consequence of a primary Campylobacter infection which typically manifests as diarrhea, there is an increased risk to suffer from post-infectious complications such as reactive arthritis, neuropathia, myositis or a Guillain-Barré Syndrome. Usually the verification of acute campylobacteriosis is made by stool culture. In contrast, post-infectious complications can be diagnosed by serological assays. Since most of them are based on whole cell lysates, an insufficient specificity results from cross-reactions between related species. Therefore, the use of recombinant antigens becomes more and more favorable. Campylobacter is able to secrete a number of proteins, which are amongst others necessary for cell invasion and therefore play a crucial role for virulence. One of these, Cj0069, has a similar specificity and sensitivity in the detection of anti-Campylobacter jejuni IgG compared to the well-established antigens OMP18 and P39. This makes it a suitable antigen for diagnosing C. jejuni post-infectious complications.

Comparison of Self-Reported Sexual Activity Among Heterosexuals with Sexual Spread of Poorly Transmittable Agents: A Minimalistic Approach to Estimating Sexual Activity Based on HIV Incidence

The aim of this study was to assess whether epidemics of sexually transmitted infections caused by poorly transmittable agents corresponded to self-reported sexual activity in a distinct population. To exemplify this, a model was used to investigate whether HIV infection incidences corresponded to the extent of sexual activity as assessed by a questionnaire-based study. The model suggested between 97 and 486 sexual contacts per German individual during a sexually active lifetime based on the annual HIV incidence of 680 among the heterosexual population reported by the German National Health Authority. This is in line with the estimated 296 sexual contacts during one's lifetime, which was indicated by questionnaire respondents. The model confirms the correspondence of self-reported sexual activity with HIV incidence as reported by the German National Health Authority. Accordingly, HIV incidence- and prevalence-based modeling of sexual activity in a population provides crude estimations in situations where a range of uncertainty is acceptable. The model's veracity is limited by a number of assumptions necessitated by the paucity of data. Nevertheless, the model may be suitable in settings where severe reporting bias has to be expected for legal or socio-cultural reasons.

Seroprevalence of Campylobacter-Specific Antibodies in two German Duck Farms - A Prospective Follow-Up Study

Several studies have shown that about 60-100% of farmed ducks are colonized by Campylobacter species. Because of this, a higher risk of campylobacteriosis among duck farm workers can be assumed. To estimate the risk of Campylobacter infections in duck farm workers, we investigated the prevalence of Campylobacter spp. in ducks of two duck farms and the seroprevalence of anti-Campylobacter antibodies (IgA and IgG) in two cohorts of workers. The first cohort consisted of high-exposed stable workers and slaughterers, which was compared to a second cohort of non-/low-exposed persons. Duck caecal swabs and serum samples were collected in 2004, 2007, and 2010. The colonization rate in the examined ducks was found to be 80-90%. The seroprevalence of anti-Campylobacter IgA and IgG antibodies among the non-exposed cohort was found to be 0.00% in all 3 years. In contrast, the exposed cohort demonstrated an IgA seroprevalence of 4.17% in 2004, 5.71% in 2007, and 0.00% in 2010 and an IgG seroprevalence of 8.33% in 2004, 0.00% in 2007, and 4.29% in 2010. In conclusion, in 2004, we observed a significantly higher anti-Campylobacter antibody seroprevalence in the exposed cohort followed by a steady reduction in 2007 and 2010 under occupational health and safety measures.

Immune response to topical sodium lauryl sulfate differs from classical irritant and allergic contact dermatitis

Sodium lauryl sulfate (SLS) is used as a control irritant in patch testing for allergic contact dermatitis (ACD). However, up to 20% of those tested react to SLS, whereby the pathophysiological basis of this reaction is still unclear. To mimic patch test reactions, we repeatedly applied SLS to the skin of wild-type mice. Reactions were compared with those in a classical ACD model induced by oxazolone and an irritant contact dermatitis (ICD) model induced by croton oil. Skin inflammation was assessed with ear thickness measurements, immunohistochemistry, qRT-PCR, and flow cytometry. Topical SLS treatment was further investigated in Flg/Hrnr-/-, Myd88/Tlr3-/-, and Rag1-/- mouse models. All three compounds caused ear swelling with different courses. Oxazolone treatment, compared with the ICD model, resulted in a greater influx of immune cells (CD4+, MHCII+, CD11b+). Similarly, SLS did not induce immune cell infiltration or expression of selected inflammatory and regulatory cytokines. SLS induced the most pronounced keratinocyte proliferation. Compared with wild-type mice, topical SLS application did not increase ear swelling in skin barrier deficient Flg/Hrnr-/- mice, but led to significantly delayed swelling in mice with defects in innate or adaptive immune functions (Myd88/Tlr3-/-, Rag1-/-). SLS-induced contact dermatitis differed from classical ACD and ICD, as it elicited less pronounced immune alterations. Skin barrier impairment does not affect SLS-induced contact dermatitis, whereas both innate and adaptive components are involved in SLS skin reactions.