The use of probiotics as prophylaxis for necrotizing enterocolitis (NEC) in preterm infants is being increasingly practised.
We report, for the first time, a case series of 3 preterm, ...very-low-birth-weight (VLBW) infants who developed bacteremia with Bifidobacterium longum on probiotic therapy with Infloran® containing viable B. longum.
We retrospectively reviewed data of 3 infants (of gestational age <30 weeks and birth weight <1,230 g). They were admitted to the neonatal intensive care unit. Clinical data were retrieved from their medical records.
In infants 1 and 2, B. longum was isolated from the blood cultures when they were on probiotic therapy with Infloran or shortly after, respectively, and was interpreted as transient bacteremia. The clinical presentation of these infants did not require antibiotic treatment after the isolation of B. longum. Infant 3 developed an NEC despite probiotic therapy with Infloran and the blood cultures showed B. longum growth. This infant required explorative laparotomy and antibiotic treatment. The clinical isolates of B. longum and the strain of the Infloran capsule showed an identical profile on biochemical, mass-spectrometric and molecular analyses, suggesting a direct correlation between the administration of probiotics and bacteremia with B. longum in all 3 infants.
The occurrence of bacteremia with bifidobacteria after its prophylactic administration in VLBW infants and its possible clinical consequences are a matter of concern. In the interests of safety, the use of probiotics in such a population should be indicated with caution and requires further investigation.
Treatment failure in biofilm-associated bacterial infections is an important healthcare issue. In vitro studies and mouse models suggest that bacteria enter a slow-growing/non-growing state that ...results in transient tolerance to antibiotics in the absence of a specific resistance mechanism. However, little clinical confirmation of antibiotic tolerant bacteria in patients exists. In this study we investigate a Staphylococcus epidermidis pacemaker-associated endocarditis, in a patient who developed a break-through bacteremia despite taking antibiotics to which the S. epidermidis isolate is fully susceptible in vitro. Characterization of the clinical S. epidermidis isolates reveals in-host evolution over the 16-week infection period, resulting in increased antibiotic tolerance of the entire population due to a prolonged lag time until growth resumption and a reduced growth rate. Furthermore, we observe adaptation towards an increased biofilm formation capacity and genetic diversification of the S. epidermidis isolates within the patient.
Aeromonas hydrophila is a gram-negative facultative anaerobic coccobacillus, which is an environmental opportunistic pathogen. A. hydrophila are involved in several infectious diseases such as ...gastroenteritis, septicemia and wound infections. However, gastroenteritis caused by Aeromonas spp. are rare and the clinical relevance of Aeromonas species in stool specimens is still under debate. Although A. hydrophila rarely causes gastroenteritis, Aeromonas spp. should be considered as a causative agent of severe gastroenteritis with a cholera-like presentation. This case highlights the need to perform culture methods from stool samples when PCR-based methods are negative and gastrointestinal infection is suspected.
Irrigation water is a major source of fresh produce contamination with undesired microorganisms including antibiotic-resistant bacteria (ARB), and contaminated fresh produce can transfer ARB to the ...consumer especially when consumed raw. Nevertheless, no legal guidelines exist so far regulating quality of irrigation water with respect to ARB. We therefore examined irrigation water from major vegetable growing areas for occurrence of antibiotic-resistant indicator bacteria Escherichia coli and Enterococcus spp., including extended-spectrum β-lactamase (ESBL)-producing E. coli and vancomycin-resistant Enterococcus spp. Occurrence of ARB strains was compared to total numbers of the respective species. We categorized water samples according to total numbers and found that categories with higher total E. coli or Enterococcus spp. numbers generally had an increased proportion of respective ARB-positive samples. We further detected high prevalence of ESBL-producing E. coli with eight positive samples of thirty-six (22%), while two presumptive vancomycin-resistant Enterococcus spp. were vancomycin-susceptible in confirmatory tests. In disk diffusion assays all ESBL-producing E. coli were multidrug-resistant (n = 21) and whole-genome sequencing of selected strains revealed a multitude of transmissible resistance genes (ARG), with blaCTX-M-1 (4 of 11) and blaCTX-M-15 (3 of 11) as the most frequent ESBL genes. Overall, the increased occurrence of indicator ARB with increased total indicator bacteria suggests that the latter might be a suitable estimate for presence of respective ARB strains. Finally, the high prevalence of ESBL-producing E. coli with transmissible ARG emphasizes the need to establish legal critical values and monitoring guidelines for ARB in irrigation water.
In this study we evaluated the commercially available LightMix® RT-PCR assay for Helicobacter pylori detection and identification of clarithromycin (CLR) resistance in culture and clinical specimens ...(gastric biopsies and stool). The H. pylori LightMix® RT-PCR detects a 97bp long fragment of the 23S rRNA gene and allows the identification of 3 distinct point mutations conferring CLR resistance via melting curve analysis. The performance of the H. pylori LightMix® RT-PCR was evaluated using a set of 60 H. pylori strains showing phenotypical CLR susceptibility or CLR resistance (Minimum inhibitory concentrations from 0.016 to 256mg/L). We found high concordance (95%) between phenotypical CLR resistance screening by E-Test® and the Lightmix® RT-PCR. Discrepant results were verified by sequencing of the 23S rRNA gene that always confirmed the results obtained by Lightmix® RT-PCR. Furthermore, H. pylori was detected in clinical biopsy and stool specimens by Lightmix® RT-PCR that identified the correct H. pylori genotype. The LightMix® RT-PCR is an accurate, sensitive and easy to use test for H. pylori and CLR resistance detection and can therefore be readily implemented in any diagnostic laboratory.
Reported matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identification rates of Gram-positive rods (GPR) are low compared to identification rates of ...Gram-positive cocci. In this study, three sample preparation methods were compared for MALDI-TOF MS identification of 190 well-characterized GPR strains: direct transfer, direct transfer-formic acid preparation, and ethanol-formic acid extraction. Using the interpretation criteria recommended by the manufacturer, identification rates were significantly higher for direct transfer-formic acid preparation and ethanol-formic acid extraction than for direct transfer. Reducing the species cutoff from 2.0 to 1.7 significantly increased species identification rates. In a subsequent prospective study, 215 clinical GPR isolates were analyzed by MALDI-TOF MS, and the results were compared to those for identification using conventional methods, with discrepancies being resolved by 16S rRNA and rpoB gene analysis. Using the direct transfer-formic acid preparation and a species cutoff of 1.7, congruencies on the genus and species levels of 87.4% and 79.1%, respectively, were achieved. In addition, the rate of nonidentified isolates dropped from 12.1% to 5.6% when using an extended database, i.e., the Bruker database amended by reference spectra of the 190 GPR of the retrospective study. Our data demonstrate three ways to improve GPR identification by the Bruker MALDI Biotyper, (i) optimize sample preparation using formic acid, (ii) reduce cutoff scores for species identification, and (iii) expand the database. Based on our results, we suggest an identification algorithm for the clinical laboratory combining MALDI-TOF MS with nucleic acid sequencing.
The rapid detection and species-level differentiation of bacterial pathogens facilitates antibiotic stewardship and improves disease management. Here, we develop a rapid bacteriophage-based ...diagnostic assay to detect the most prevalent pathogens causing urinary tract infections: Escherichia coli, Enterococcus spp., and Klebsiella spp. For each uropathogen, two virulent phages were genetically engineered to express a nanoluciferase reporter gene upon host infection. Using 206 patient urine samples, reporter phage-induced bioluminescence was quantified to identify bacteriuria and the assay was benchmarked against conventional urinalysis. Overall, E. coli, Enterococcus spp., and Klebsiella spp. were each detected with high sensitivity (68%, 78%, 87%), specificity (99%, 99%, 99%), and accuracy (90%, 94%, 98%) at a resolution of ≥10
CFU/ml within 5 h. We further demonstrate how bioluminescence in urine can be used to predict phage antibacterial activity, demonstrating the future potential of reporter phages as companion diagnostics that guide patient-phage matching prior to therapeutic phage application.
Propionibacteria are important members of the human skin microbiota, but are also opportunistic pathogens associated with periprosthetic joint infection (PJI). While the role of Propionibacterium ...acnes in PJI has been widely described, insight into the capacity of Propionibacterium avidum to cause PJI is limited.
An unusual cluster of 4 hip PJIs caused by P. avidum in one orthopedic center in 2015 prompted us to retrospectively identify and analyze clinical data related to previous P. avidum PJI cases (1997-2015). We also characterized the hemolytic and biofilm-producing capacity of our 4 clinical P. avidum strains isolated in 2015, and investigated their phylogenetic relationships by whole-genome sequencing.
We retrospectively identified 13 P. avidum PJIs, with the majority being hip-related infections (n = 11). Preoperative synovial fluid cultures were P. avidum positive in 63.6% of cases. Six of 12 patients (50%) with available case histories were treated with an exchange of the prosthesis. In all but 1 of the 6 patients treated with debridement-retention of the prosthesis, treatment failed, thus requiring a 2-stage revision. The isolated P. avidum strains showed a more pronounced hemolytic activity, but a similar biofilm-forming ability when compared to P. acnes. Whole-genome sequencing identified 2 phylogenetic clusters highly related to P. avidum PJI strains isolated in Sweden.
We describe the largest series of P. avidum PJI predominantly located in the hip. Phylogenetic similarity of our P. avidum strains to PJI strains isolated elsewhere suggests that these invasive lineages may be common.
A multitude of definitions determining multidrug resistance (MDR) of Gram-negative organisms exist worldwide. The definitions differ depending on their purpose and on the issueing country or ...organization. The MDR definitions of the European Centre for Disease Prevention and Control (ECDC) were primarily chosen to harmonize epidemiological surveillance. The German Commission of Hospital Hygiene and Infection Prevention (KRINKO) issued a national guideline which is mainly used to guide infection prevention and control (IPC) measures. The Swiss University Hospital Zurich (UHZ) - in absentia of national guidelines - developed its own definition for IPC purposes. In this study we aimed to determine the effects of different definitions of multidrug-resistance on rates of Gram-negative multidrug-resistant organisms (GN-MDRO).
MDR definitions of the ECDC, the German KRINKO and the Swiss University Hospital Zurich were applied on a dataset comprising isolates of
,
sp.
and
complex. Rates of GN-MDRO were compared and the percentage of patients with a GN-MDRO was calculated.
In total 11'407 isolates from a 35 month period were included. For
and
highest MDR-rates resulted from applying the 'ECDC-MDR' definition. 'ECDC-MDR' rates were up to four times higher compared to 'KRINKO-3/4MRGN' rates, and up to six times higher compared to UHZ rates. Lowest rates were observed when applying the 'KRINKO-4MRGN' definitions. Comparing the 'KRINKO-3/4MRGN' with the UHZ definitions did not show uniform trends, but yielded higher rates for
and lower rates for
. On the patient level, the percentages of GN-MDRO carriers were 2.1, 5.5, 6.6, and 18.2% when applying the 'KRINKO-4MRGN', 'UHZ-MDR', 'KRINKO-3/4MRGN', and the 'ECDC-MDR' definition, respectively.
Different MDR-definitions lead to considerable variation in rates of GN-MDRO. Differences arise from the number of antibiotic categories required to be resistant, the categories and drugs considered relevant, and the antibiotic panel tested. MDR definitions should be chosen carefully depending on their purpose and local resistance rates, as definitions guiding isolation precautions have direct effects on costs and patient care.
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