Authors:Ralf Matthias Hagen, Hagen Hinz, and Hagen Frickmann
ESBL (extended-spectrum-β-lactamase)-positive Enterobacteriaceae, which colonized European soldiers in tropical Western African Mali, were subjected to a molecular assessment of their resistance determinants. By doing so, a better insight into the locally endemic pattern of ESBL-associated β-lactamase genes was aspired.
From a previous study on diarrhea in European soldiers on deployment in tropical Mali, 15 ESBL-positive Escherichia coli with demonstrated high clonal diversity and one positive Klebsiella pneumoniae were assessed. Polymerase chain reactions (PCRs) for blaTEM and blaSHV β-lactamase genes with subsequent sequencing for the discrimination of ESBL- and non-ESBL variants were performed, followed by four group-specific PCRs for blaCTX-M genes.
Non-ESBL-associated blaTEM-1 was identified in six out of 15 (40%) E. coli strains, while 100% of the assessed strains were positive for group I blaCTX-M.
Considering the known clonal diversity of the assessed strains, the striking restriction to one group of blaCTX-M genes accounting for the ESBL phenotypes of the isolates suggests little genetic exchange in the local setting. Under such circumstances of restricted numbers of locally endemic target genes, PCR-based screening approaches for ESBL colonization might be promising.
Authors:Ralf Matthias Hagen, Rebecca Hinz, Egbert Tannich, and Hagen Frickmann
We compared the performance of an in-house and a commercial malaria polymerase chain reaction (PCR) assay using freeze–thawed hemolytic blood samples.
A total of 116 freeze–thawed ethylenediamine tetraacetic acid (EDTA) blood samples of patients with suspicion of malaria were analyzed by an in-house as well as by a commercially available real-time PCR.
Concordant malaria negative PCR results were reported for 39 samples and malaria-positive PCR results for 67 samples. The inhouse assay further detected one case of Plasmodium falciparum infection, which was negative in the commercial assay as well as five cases of P. falciparum malaria and three cases of Plasmodium vivax malaria, which showed sample inhibition in the commercial assay. The commercial malaria assay was positive in spite of a negative in-house PCR result in one case. In all concordant results, cycle threshold values of P. falciparum-positive samples were lower in the commercial PCR than in the in-house assay.
Although Ct values of the commercial PCR kit suggest higher sensitivity in case of concordant results, it is prone to inhibition if it is applied to hemolytic freeze–thawed blood samples. The number of misidentifications was, however, identical for both real-time PCR assays.
Authors:Maria Franziska Ostermann, Heinrich Neubauer, Hagen Frickmann, and Ralf Matthias Hagen
This study assessed the variation of phenotypic features of clinical isolates of Burkholderia spp. from common rpsU gene sequence clusters.
A total of 41 clinical Burkholderia spp. isolates from German mucoviscidosis patients was subjected to rpsU gene sequencing. Biochemical assessment included the API systems 20 NE and 50 CHE as well as the Micronaut NF system. Fatty acid patterns were assessed using gas chromatography—mass spectrometry (GC—MS). Broth microdilution was used to identify minimum inhibitory concentrations.
Five rpsU gene sequence clusters comprised more than one clinical isolate. Altogether, assignments to three species and seven clusters comprising more than one Burkholderia species were performed. Inhomogeneity of biochemical reactions within the clusters ranged from 0/28 to 45/50 reactions. The standard deviation for fatty acid distributions ranged from 0% to 11.5%. Minimum inhibitory concentrations within the clusters showed a wide variation but only minor differences between the clusters.
Broad variations within identified rpsU gene sequence clusters regarding biochemical reactions, fatty acid patterns, and resistance patterns of clinical Burkholderia spp. isolates make the application of rpsU gene sequence analysis as a stand-alone procedure for discriminations within the Burkholderia cepacia complex unreliable.
Authors:Sonja Obersteller, Heinrich Neubauer, Ralf Matthias Hagen, and Hagen Frickmann
The extraction and further processing of nucleic acids (NA) from formalin-fixed paraffin-embedded (FFPE) tissues for microbiological diagnostic polymerase chain reaction (PCR) approaches is challenging. Here, we assessed the effects of five different commercially available nucleic acid extraction kits on the results of real-time PCR.
FFPE samples from organs of Burkholderia pseudomallei-infected Swiss mice were subjected to processing with five different extraction kits from QIAGEN (FFPE DNA Tissue Kit, EZ1 DNA Tissue Kit, DNA Mini Kit, DNA Blood Mini Kit, and FlexiGene DNA Kit) in combination with three different real-time PCRs targeting B. pseudomallei-specific sequences of varying length after 16 years of storage.
The EZ1 DNA Tissue Kit and the DNA Mini Kit scored best regarding the numbers of successful PCR reactions. In case of positive PCR, differences regarding the cycle-threshold (Ct) values were marginal.
The impact of the applied extraction kits on the reliability of PCR from FFPE material seems to be low. Interfering factors like the quality of the dewaxing procedure or the sample age appear more important than the selection of specialized FFPE kits.
Authors:Matthias Halfter, Ulrich Müseler, Ralf Matthias Hagen, and Hagen Frickmann
The study was performed to assess the infection risk of German police officers on predominantly tropical deployments, mostly United Nations missions, with gastrointestinal pathogens.
Police officers were offered PCR-based screening for gastrointestinal pathogens before and after deployment. The screening panel comprised enteroinvasive bacteria (Salmonella spp., Shigella spp./enteroinvasive Escherichia coli, Campylobacter jejuni, and Yersinia spp.), enteropathogenic protozoa (Entamoeba histolytica, Giardia duodenalis, Cryptosporidium spp., and Cyclospora cayetanensis), as well as enteric helminths (Ancyclostoma spp., Ascaris lumbricoides, Enterobius vermicularis, Hymenolepis nana, Necator americanus, African Schistosoma spp., Strongyloides stercoralis, Taenia saginata, Taenia solium, and Trichuris trichiura).
G. duodenalis (n = 3), C. jejuni (n = 2), Salmonella spp. (n = 1), Shigella spp./enteroinvasive E. coli (n = 3), and S. stercoralis (n = 3) were detect in 12 out of 133 (9.0%) police officers. The majority had shown gastrointestinal symptoms on deployment and all were asymptomatic at the time of medical assessment. The major infection sites were Sub-Saharan Africa followed by Northern Africa and the Middle East.
Deployment of police officers to tropical deployment sites on United Nations missions is associated with a considerable acquisition risk of gastrointestinal pathogens in a quantitatively relevant minority. Post-deployment screening is advisable to facilitate therapeutic and hygiene-related consequences.
Authors:Carola Edler, Henri Derschum, Mirko Köhler, Heinrich Neubauer, Hagen Frickmann, and Ralf Matthias Hagen
Reliable identification of pathogenic Burkholderia spp. like Burkholderia mallei and Burkholderia pseudomallei in clinical samples is desirable. Three different selective media were assessed for reliability and selectivity with various Burkholderia spp. and nontarget organisms.
Mast Burkholderia cepacia agar, Ashdown + gentamicin agar, and B. pseudomallei selective agar were compared. A panel of 116 reference strains and well-characterized clinical isolates, comprising 30 B. pseudomallei, 20 B. mallei, 18 other Burkholderia spp., and 48 nontarget organisms, was used for this assessment.
While all B. pseudomallei strains grew on all three tested selective agars, the other Burkholderia spp. showed a diverse growth pattern. Nontarget organisms, i.e., nonfermentative rod-shaped bacteria, other species, and yeasts, grew on all selective agars. Colony morphology did not allow unambiguous discrimination.
While the assessed selective media reliably allowed the growth of a wide range of B. pseudomallei strains, growth of other Burkholderia spp. is only partially ensured. Growth of various nontarget organisms has to be considered. Therefore, the assessed media can only be used in combination with other confirmative tests in the diagnostic procedure for the screening for melioidosis or glanders.
Authors:Julia Münch, Ralf Matthias Hagen, Martin Müller, Viktor Kellert, Dorothea Franziska Wiemer, Rebecca Hinz, Norbert Georg Schwarz, and Hagen Frickmann
The effectiveness of a disinfectant-based decolonization strategy for multidrug-resistant bacteria like extended spectrum β-lactamase (ESBL)-positive Gram-negative bacteria with or without additional fluoroquinolon and carbapenem resistance as well as vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus was assessed.
Between 2011 and 2015, 25 patients from Libya, Syria, and the Ukraine with war traumata were treated at the Bundeswehr hospital Hamburg. The patients were heavily colonized and infected with multidrug-resistant bacteria, altogether comprising 371 distinct combinations of pathogens and isolation sites. Local disinfection was assessed for effectiveness regarding successful decolonization of multidrug-resistant bacteria.
Altogether, 170 cases of successful decolonization were observed, comprising 95 (55.8%) such events at sampling sites that were accessible to disinfecting procedures. The remaining 75 (44.2%) decolonization events had to be considered as spontaneous. In contrast, 95 out of 172 (55.2%) colonized isolation sites that were accessible to disinfection procedures were successfully decolonized. Patient compliance with the enforced hygiene procedures was associated with decolonization success. Systemic antibiotic therapy did not relevantly affect isolation time.
Disinfecting washing moderately supports local decolonization of multidrug-resistant pathogens in comparison with spontaneous decolonization rates if the patients’ compliance with the applied hygiene procedures is ensured.
Authors:Heike Granzer, Ralf Matthias Hagen, Philipp Warnke, Wolfgang Bock, Tobias Baumann, Norbert Georg Schwarz, Andreas Podbielski, Hagen Frickmann, and Thomas Koeller
This study addressed carbapenem-resistant Acinetobacter baumannii complex (ABC) isolates from patients that were injured during the military conflict in the Eastern Ukraine and treated at German Armed Forces Hospitals in 2014 and 2015. Clonal diversity of the strains and potential ways of transmission were analyzed.
Patients with one or several isolation events of carbapenem-resistant ABC were included. Isolates were characterized by VITEK II-based identification and resistance testing, molecular screening for frequent carbapenemase genes, and DiversiLab rep-PCRbased typing. Available clinical information of the patients was assessed.
From 21 young male Ukrainian patients with battle injuries, 32 carbapenem- and fluoroquinolone-resistant ABC strains were isolated. Four major clonal clusters were detected. From four patients (19%), ABC isolates from more than one clonal cluster were isolated. The composition of the clusters suggested transmission events prior to the admission to the German hospitals.
The infection and colonization pressure in the conflict regions of the Eastern Ukraine with ABC of low clonal diversity is considerable. Respective infection risks have to be considered in case of battle-related injuries in these regions. The low number of local clones makes any molecular exclusion of transmission events difficult.
Authors:Dorothea Wiemer, Norbert Georg Schwarz, Gerd-Dieter Burchard, Hagen Frickmann, Ulrike Loderstaedt, and Ralf-Matthias Hagen
Diarrhoea is a frequent symptom associated with travelling to tropical regions, but the cause is often not found. Epidemiology was assessed including up-to-date real-time PCR approaches.
We analysed datasets of 528 patients who presented at the Bernhard Nocht Institute for Tropical Medicine in Hamburg, Germany, between 2006 and 2010 for screening purposes or because of diarrhoea. Stool samples were obtained and investigated by microscopy, bacterial culture, two PCR assays targeting Entamoeba histolytica, Entamoeba dispar, Giardia duodenalis, and Cryptosporidium parvum, or Salmonella spp., Shigella/EIEC spp., Campylobacter jejuni, and Yersinia spp.
Among patients with gastrointestinal symptoms, 51% tested positive for bacteria or parasites, of which 66% had a known enteropathogenic potential. In patients without diarrhoea, 53% (n = 80) were positive, and 33% of these cases harboured agents of pathogenic potential. Association with clinical symptoms was primarily found for bacterial infections. Blastocystis hominis, however, was more frequent in asymptomatic than in symptomatic travellers.
In conclusion, the study stresses the etiological relevance of bacterial gastroenteritis in travellers returning from the tropics, the need for molecular approaches to increase diagnostic sensitivity and demonstrates that asymptomatic carriage of enteropathogens after prolonged stays in the tropics is similarly frequent compared with symptomatic infections in travellers.
Authors:Hans Kollenda, Ralf Matthias Hagen, Miriam Hanke, Sandra Rojak, Rebecca Hinz, Lars Wassill, Sven Poppert, Egbert Tannich, and Hagen Frickmann
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.