Ines Engelmann

Surveillance of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in Dairy Cattle Farms in the Nile Delta, Egypt.

Introduction: Industrial livestock farming is a possible source of multi-resistant Gram-negative bacteria, including producers of extended spectrum beta-lactamases (ESBLs) conferring resistance to 3rd generation cephalosporins. Limited information is currently available on the situation of ESBL producers in livestock farming outside of Western Europe. A surveillance study was conducted from January to May in 2014 in four dairy cattle farms in different areas of the Nile delta, Egypt. Materials and Methods: In total, 266 samples were collected from 4 dairy farms including rectal swabs from clinically healthy cattle (n = 210), and environmental samples from the stalls (n = 56). After 24 h pre-enrichment in buffered peptone water, all samples were screened for 3rd generation cephalosporin-resistant Escherichia coli using Brilliance™ ESBL agar. Suspected colonies of putatively ESBL-producing E. coli were sub-cultured and subsequently genotypically and phenotypically characterized. Susceptibility testing using the VITEK-2 system was performed. All suspect isolates were genotypically analyzed using two DNA-microarray based assays: CarbDetect AS-1 and E. coli PanType AS-2 kit (ALERE). These tests allow detection of a multitude of genes and their alleles associated with resistance toward carbapenems, cephalosporins, and other frequently used antibiotics. Serotypes were determined using the E. coli SeroGenotyping AS-1 kit (ALERE). Results: Out of 266 samples tested, 114 (42.8%) ESBL-producing E. coli were geno- and phenotypically identified. 113 of 114 phenotypically 3rd generation cephalosporin-resistant isolates harbored at least one of the ESBL resistance genes covered by the applied assays [blaCTX-M15 (n = 105), blaCTX-M9 (n = 1), blaTEM (n = 90), blaSHV (n = 1)]. Alarmingly, the carbapenemase genes blaOXA-48 (n = 5) and blaOXA-181 (n = 1) were found in isolates that also were phenotypically resistant to imipenem and meropenem. Using the array-based serogenotyping method, 66 of the 118 isolates (55%) could be genotypically assigned to O-types. Conclusion: This study is considered to be a first report of the high prevalence of ESBL-producing E. coli in dairy farms in Egypt. ESBL-producing E. coli isolates with different underlying resistance mechanisms are common in investigated dairy cattle farms in Egypt. The global rise of ESBL- and carbapenemase-producing Gram-negative bacteria is a big concern, and demands intensified surveillance.

Distribution of SCCmec-associated phenol-soluble modulin in staphylococci

The recently described phenol-soluble modulin PSM-mec was detected in Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus fleuretti, Staphylococcus hominis, Staphylococcus pseudintermedius, Staphylococcus saprophyticus, Staphylococcus simulans and Staphylococcus vitulinus from different hosts (humans, goats, dogs, cats, pigs, cattle and turkeys). It was identified in isolates harbouring SCCmec types II, IIA, IIB, IID, III, VIII and in some irregular or truncated elements.

Rapid microarray-based DNA genoserotyping of Escherichia coli.

In this study, an improvement in the oligonucleotide‐based DNA microarray for the genoserotyping of Escherichia coli is presented. Primer and probes for additional 70 O antigen groups were developed. The microarray was transferred to a new platform, the ArrayStrip format, which allows high through‐put tests in 96‐well formats and fully automated microarray analysis. Thus, starting from a single colony, it is possible to determine within a few hours and a single experiment, 94 of the over 180 known O antigen groups as well as 47 of the 53 different H antigens. The microarray was initially validated with a set of defined reference strains that had previously been serotyped by conventional agglutination in various reference centers. For further validation of the microarray, 180 clinical E. coli isolates of human origin (from urine samples, blood cultures, bronchial secretions, and wound swabs) and 53 E. coli isolates from cattle, pigs, and poultry were used. A high degree of concordance between the results of classical antibody‐based serotyping and DNA‐based genoserotyping was demonstrated during validation of the new 70 O antigen groups as well as for the field strains of human and animal origin. Therefore, this oligonucleotide array is a diagnostic tool that is user‐friendly and more efficient than classical serotyping by agglutination. Furthermore, the tests can be performed in almost every routine lab and are easily expanded and standardized.

Rapid Spoligotyping of Mycobacterium tuberculosis Complex Bacteria by Use of a Microarray System with Automatic Data Processing and Assignment

ABSTRACT Membrane-based spoligotyping has been converted to DNA microarray format to qualify it for high-throughput testing. We have shown the assays validity and suitability for direct typing from tissue and detecting new spoligotypes. Advantages of the microarray methodology include rapidity, ease of operation, automatic data processing, and affordability.

Development of a Rapid Microarray-Based DNA Subtyping Assay for the Alleles of Shiga Toxins 1 and 2 of Escherichia coli

ABSTRACT In this study, we developed a new rapid, economic, and automated microarray-based genotyping test for the standardized subtyping of Shiga toxins 1 and 2 of Escherichia coli. The microarrays from Alere Technologies can be used in two different formats, the ArrayTube and the ArrayStrip (which enables high-throughput testing in a 96-well format). One microarray chip harbors all the gene sequences necessary to distinguish between all Stx subtypes, facilitating the identification of single and multiple subtypes within a single isolate in one experiment. Specific software was developed to automatically analyze all data obtained from the microarray. The assay was validated with 21 Shiga toxin-producing E. coli (STEC) reference strains that were previously tested by the complete set of conventional subtyping PCRs. The microarray results showed 100% concordance with the PCR results. Essentially identical results were detected when the standard DNA extraction method was replaced by a time-saving heat lysis protocol. For further validation of the microarray, we identified the Stx subtypes or combinations of the subtypes in 446 STEC field isolates of human and animal origin. In summary, this oligonucleotide array represents an excellent diagnostic tool that provides some advantages over standard PCR-based subtyping. The number of the spotted probes on the microarrays can be increased by additional probes, such as for novel alleles, species markers, or resistance genes, should the need arise.

A multiplex real-time PCR for the direct, fast, economic and simultaneous detection of the carbapenemase genes blaKPC, blaNDM, blaVIM and blaOXA-48.

A novel multiplex real-time PCR was designed to detect the clinically most important carbapenemase genes, blaKPC, blaVIM, blaNDM and blaOXA-48. The multiplex assay was verified testing genomic DNA of 24 carbapenemase-producing strains. It was validated using a blinded panel of 82 carbapenemase-producing and 50 non-producing isolates by direct colony PCR.

Influence of polymerase brand on microarray-based spoligotyping in low concentrations of mycobacterial DNA

Spoligotyping is a widely used typing method for the Mycobacterium tuberculosis complex. Protocols and platforms can be adapted for direct use on patient samples. Serial dilutions of genomic DNA from Mycobacterium bovis BCG strain DSM45071 were spoligotyped by array hybridization using 32 different commercial PCR polymerase preparations. In samples with very low concentrations of mycobacterial DNA, commercially available PCR polymerases differed in their performance, and some yielded no, or false, identification. Direct spoligotyping from samples with very low concentrations of mycobacterial DNA thus requires careful selection of polymerase and strict standardization.

DNA-Microarray-based Genotyping of Clostridium difficile

BackgroundClostridium difficile can cause antibiotic-associated diarrhea and a possibility of outbreaks in hospital settings warrants molecular typing. A microarray was designed that included toxin genes (tcdA/B, cdtA/B), genes related to antimicrobial resistance, the slpA gene and additional variable genes.ResultsDNA of six reference strains and 234 clinical isolates from South-Western and Eastern Germany was subjected to linear amplification and labeling with dUTP-linked biotin. Amplicons were hybridized to microarrays providing information on the presence of target genes and on their alleles. Tested isolates were assigned to 37 distinct profiles that clustered mainly according to MLST-defined clades. Three additional profiles were predicted from published genome sequences, although they were not found experimentally.ConclusionsThe microarray based assay allows rapid and high-throughput genotyping of clinical C. difficile isolates including toxin gene detection and strain assignment. Overall hybridization profiles correlated with MLST-derived clades.

Prevalence of carbapenemase-producing organisms at the Kidney Center of Rawalpindi (Pakistan) and evaluation of an advanced molecular microarray-based carbapenemase assay

AIM A DNA microarray-based assay for the detection of antimicrobial resistance (AMR) genes was used to study carbapenemase-producing organisms at the Kidney Center of Rawalpindi, Pakistan. METHODS The evaluation of this assay was performed using 97 reference strains with confirmed AMR genes. Testing of 7857 clinical samples identified 425 Gram-negative bacteria out of which 82 appeared carbapenem resistant. These isolates were analyzed using VITEK-2 for phenotyping and the described AMR assay for genotyping. RESULTS The most prevalent carbapenemase gene was blaNDM and in 12 isolates we detected two carbapenemase genes (e.g., blaNDM/blaOXA-48). CONCLUSION Our prevalence data from Pakistan show that - as in other parts of the world - carbapenemase-producing organisms with different underlying resistance mechanisms are emerging, and this warrants intensified and constant surveillance.