Ortrud Zimmermann

Clostridium difficile Toxinotype V, Ribotype 078, in Animals and Humans

Two publications describing the important role of Clostridium difficile PCR ribotype 078 were published recently in the Journal of Clinical Microbiology. Keel and coworkers have described variability of C. difficile types isolated in animals and reported ribotype 078 to be most prevalent in isolates

Rapid Discrimination of Salmonella enterica Serovar Typhi from Other Serovars by MALDI-TOF Mass Spectrometry

Systemic infections caused by Salmonella enterica are an ongoing public health problem especially in Sub-Saharan Africa. Essentially typhoid fever is associated with high mortality particularly because of the increasing prevalence of multidrug-resistant strains. Thus, a rapid blood-culture based bacterial species diagnosis including an immediate sub-differentiation of the various serovars is mandatory. At present, MALDI-TOF based intact cell mass spectrometry (ICMS) advances to a widely used routine identification tool for bacteria and fungi. In this study, we investigated the appropriateness of ICMS to identify pathogenic bacteria derived from Sub-Saharan Africa and tested the potential of this technology to discriminate S. enterica subsp. enterica serovar Typhi (S. Typhi) from other serovars. Among blood culture isolates obtained from a study population suffering from febrile illness in Ghana, no major misidentifications were observed for the species identification process, but serovars of Salmonella enterica could not be distinguished using the commercially available Biotyper database. However, a detailed analysis of the mass spectra revealed several serovar-specific biomarker ions, allowing the discrimination of S. Typhi from others. In conclusion, ICMS is able to identify isolates from a sub-Saharan context and may facilitate the rapid discrimination of the clinically and epidemiologically important serovar S. Typhi and other non-S. Typhi serovars in future implementations.

Surface-associated motility, a common trait of clinical isolates of Acinetobacter baumannii, depends on 1,3-diaminopropane.

While flagella-independent motility has long been described in representatives of the genus Acinetobacter, the mechanism of motility remains ambiguous. Acinetobacter baumannii, a nosocomial pathogen appearing increasingly multidrug-resistant, may profit from motility during infection or while persisting in the hospital environment. However, data on the frequency of motility skills among clinical A. baumannii isolates is scarce. We have screened a collection of 83 clinical A. baumannii isolates of different origin and found that, with the exception of one isolate, all were motile on wet surfaces albeit to varying degrees and exhibiting differing morphologies. Screening a collection of transposon mutants of strain ATCC 17978 for motility defects, we identified 2 akinetic mutants carrying transposon insertions in the dat and ddc gene, respectively. These neighbouring genes contribute to synthesis of 1,3-diaminopropane (DAP), a polyamine ubiquitously produced in Acinetobacter. Supplementing semi-solid media with DAP cured the motility defect of both mutants. HPLC analyses confirmed that DAP synthesis was abolished in ddc and dat mutants of different A. baumannii isolates and was re-established after genetic complementation. Both, the dat and ddc mutant of ATCC 17978 were attenuated in the Galleria mellonella caterpillar infection model. Taken together, surface-associated motility is a common trait of clinical A. baumannii isolates that requires DAP and may play a role in its virulence.

Bacteremia and Antimicrobial Drug Resistance over Time, Ghana

Bacterial distribution and antimicrobial drug resistance were monitored in patients with bacterial bloodstream infections in rural hospitals in Ghana. In 2001–2002 and in 2009, Salmonella enterica serovar Typhi was the most prevalent pathogen. Although most S. enterica serovar Typhi isolates were chloramphenicol resistant, all isolates tested were susceptible to ciprofloxacin.

Corynebacterium thomssenii sp. nov., a Corynebacterium with N/acetyl-β-glucosaminidase activity from human clinical specimens

A strain of a previously undescribed non-lipophilic coryneform bacterium was isolated from pleural fluids of a patient with chronic renal failure, stroke and pneumonia. Slow fermentative acid production from glucose, maltose and sucrose, and strong N-acetyl-beta-glucosaminidase activity were the most characteristic features of the bacterium. Chemotaxonomic characterization unambiguously indicated that the organism belonged to the genus Corynebacterium. The results of comparative 16S rRNA gene sequence analysis revealed that the isolate represented a new species within the genus, for which the name Corynebacterium thomssenii sp. nov. is proposed. The type strain is DSM 44276.

Stability of genomic DNA fragment patterns in methicillin resistant Staphylococcus aureus (MRSA) during the course of intra- and interhospital spread

The analysis of genomic DNA fragment patterns has revealed as a powerful tool for strain discrimination inStaphylococcus aureus; for use as an epidemiological marker, stability during the course of an outbreak is an essential prerequisite. Genomic DNA fragment patterns (SmaI restriction, pulsed-field electrophoresis) of four different epidemic MRSA strains were compared along with intra- and interhospital and country-wide spread over more than 12 months in Germany. Strain I was isolated from infections in 8 hospitals. In one hospital a subclone arised which differed from the original strain by 4 fragments. Strain II was spread among 4 hospitals, isolates from three of these hospitals exhibited a variability of one to three fragments in the 150–200 kb range. Two hospitals in the Hannover-area were affected by strain III; in 17 isolates of this strain a variability up to three fragments was found in the 170–200 kb range. Strain IV was isolated from 19 cases of infections in 3 hospitals in Berlin. The fragment patterns were completely stable. When S. aureus strains are typed by genomic DNA fragment patterns, a variability in a definite range of molecular masses during the course of an epidemic should be taken into consideration.

The Reduction in Antibiotic Use in Hospitals.

BACKGROUND Over 350 000 patients are treated in German hospitals for sepsis or pneumonia each year. The rate of antibiotic use in hospitals is high. The growing problem of drug resistance necessitates a reconsideration of antibiotic treatment strategies. METHODS Antibiotics were given liberally in the years 2010 and 2011 in a German 312-bed hospital. Special training, standardized algorithms to prevent unnecessary drug orders, and uniform recommendations were used in 2012 and 2013 to lessen antibiotic use. We retrospectively studied the hospitals mortality figures and microbiological findings to analyze how well these measures worked. RESULTS Antibiotic consumption fell from 67.1 to 51.0 defined daily doses (DDD) per 100 patient days (p <0.001) from the period 2010-2011 to the period 2012-2013. The mortality of patients with a main diagnosis of sepsis fell from 1% (95/305) to 19% (63/327; p = 0.001), while that of patients with a main diagnosis of pneumonia fell from 12% (22/178) to 6% (15/235; p = 0.038). The overall mortality fell from 3.0% (623/ 20 954) to 2.5% (576/22 719; p = 0.005). In patients with nosocomial urinary tract infections with Gram-negative pathogens (not necessarily exhibiting three- or fourfold drug resistance), the rate of resistance to three or four of the antibiotics tested fell from 11% to 5%. CONCLUSION Reducing in-hospital antibiotic use is an achievable goal and was associated in this study with lower mortality and less drug resistance. The findings of this single-center, retrospective study encourage a more limited and focused approach to the administration of antibiotics.

Two cases of chronic suppurative otitis media caused by Kerstersia gyiorum in Tanzania: is it an underappreciated pathogen in chronic otitis media?

Two cases of mixed infection involving Kerstersia gyiorum causing chronic suppurative otitis media (CSOM) have been reported worldwide. We report, for the first time, two cases of CSOM due to mixed infections involving K. gyiorum in adults in Africa. Both isolates were intermediate susceptible to ciprofloxacin based on European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints.

Comparative genome and phenotypic analysis of three Clostridioides difficile strains isolated from a single patient provide insight into multiple infection of C. difficile.

BackgroundClostridioides difficile infections (CDI) have emerged over the past decade causing symptoms that range from mild, antibiotic-associated diarrhea (AAD) to life-threatening toxic megacolon. In this study, we describe a multiple and isochronal (mixed) CDI caused by the isolates DSM 27638, DSM 27639 and DSM 27640 that already initially showed different morphotypes on solid media.ResultsThe three isolates belonging to the ribotypes (RT) 012 (DSM 27639) and 027 (DSM 27638 and DSM 27640) were phenotypically characterized and high quality closed genome sequences were generated. The genomes were compared with seven reference strains including three strains of the RT 027, two of the RT 017, and one of the RT 078 as well as a multi-resistant RT 012 strain. The analysis of horizontal gene transfer events revealed gene acquisition incidents that sort the strains within the time line of the spread of their RTs within Germany. We could show as well that horizontal gene transfer between the members of different RTs occurred within this multiple infection. In addition, acquisition and exchange of virulence-related features including antibiotic resistance genes were observed. Analysis of the two genomes assigned to RT 027 revealed three single nucleotide polymorphisms (SNPs) and apparently a regional genome modification within the flagellar switch that regulates the fli operon.ConclusionOur findings show that (i) evolutionary events based on horizontal gene transfer occur within an ongoing CDI and contribute to the adaptation of the species by the introduction of new genes into the genomes, (ii) within a multiple infection of a single patient the exchange of genetic material was responsible for a much higher genome variation than the observed SNPs.

High metabolic versatility of different toxigenic and non-toxigenic Clostridioides difficile isolates

Clostridioides difficile (formerly Clostridium difficile) is a major nosocomial pathogen with an increasing number of community-acquired infections causing symptoms from mild diarrhea to life-threatening colitis. The pathogenicity of C. difficile is considered to be mainly associated with the production of genome-encoded toxins A and B. In addition, some strains also encode and express the binary toxin CDT. However; a large number of non-toxigenic C. difficile strains have been isolated from the human gut and the environment. In this study, we characterized the growth behavior, motility and fermentation product formation of 17 different C. difficile isolates comprising five different major genomic clades and five different toxin inventories in relation to the C. difficile model strains 630Δerm and R20291. Within 33 determined fermentation products, we identified two yet undescribed products (5-methylhexanoate and 4-(methylthio)-butanoate) of C. difficile. Our data revealed major differences in the fermentation products obtained after growth in a medium containing casamino acids and glucose as carbon and energy source. While the metabolism of branched chain amino acids remained comparable in all isolates, the aromatic amino acid uptake and metabolism and the central carbon metabolism-associated fermentation pathways varied strongly between the isolates. The patterns obtained followed neither the classification of the clades nor the ribotyping patterns nor the toxin distribution. As the toxin formation is strongly connected to the metabolism, our data allow an improved differentiation of C. difficile strains. The observed metabolic flexibility provides the optimal basis for the adaption in the course of infection and to changing conditions in different environments including the human gut.