Emergence and control of linezolid-resistant Staphylococcus epidermidis in an ICU of a German hospital

Objectives

To investigate an outbreak of linezolid-resistant Staphylococcus epidermidis (LRSE) in an interdisciplinary ICU, linezolid consumption and infection control measures taken.

Methods

Routine surveillance of nosocomial infections revealed colonization and infection with LRSE affecting 14 patients during a 15 month period. LRSE isolates were analysed with respect to their clonal relatedness, antimicrobial susceptibility, the presence of cfr and/or mutations in the 23S rRNA, rplC, rplD and rplV genes. cfr plasmids were characterized by Illumina sequencing. Medical records were reviewed and antibiotic consumption was determined.

Results

Molecular typing identified the presence of three different LRSE clusters: PFGE type I/ST168 (n = 5), PFGE type II/ST5 (n = 10) and PFGE type III/ST2 (n = 1). Ten strains harboured the cfr gene; we also detected mutations in the respective ribosomal protein genes. WGS revealed an almost identical 39 kb cfr plasmid obtained from strains of different genetic background (ST2, ST5, ST168) that shows high similarity to the recently published LRSE plasmid p12-02300. Due to an increase in the number of patients treated for infections with MRSA, a significant increase in linezolid usage was noted from January to July 2014 (from 5.55 to 20.41 DDDs/100 patient-days).

Conclusions

Here, we report the molecular epidemiology of LRSE in an ICU. Our results suggest the selection of resistant mutants under linezolid treatment as well as the spread of cfr-carrying plasmids. The reduction of linezolid usage and the strengthening of contact precautions proved to be effective infection control measures.

Reduction of nosocomial bloodstream infections and nosocomial vancomycin-resistant Enterococcus faecium on an intensive care unit after introduction of antiseptic octenidine-based bathing

BACKGROUND

Vancomycin-resistant Enterococcus faecium (VRE) is emerging in German intensive care units (ICUs). On a 32-bed surgical ICU at a university hospital, increasing numbers of nosocomial cases occurred despite enforcement of hand hygiene and environmental disinfection.

AIM

To introduce universal octenidine-based bathing in order to reduce the burden of VRE.

METHODS

Between January 2012 and March 2014, patients were screened for VRE on admission and twice weekly. Active surveillance was undertaken for VRE infections and colonizations, and for bloodstream infections (BSI) with any pathogen. Intervention in this before-after study comprised of standardized octenidine-based bathing. Distinct subgroups of VRE colonizations or infections were defined and used for statistical analysis of frequency, prevalence and incidence density.

FINDINGS

In the pre-intervention period (January 2012 to April 2013), the admission prevalence of VRE was 4/100 patients and the mean incidence density of nosocomial cases was 7.55/1000 patient-days (PD). Pulsed-field gel electrophoresis analysis revealed prevalence of three vanA and two vanB clusters. In the post-intervention period (August 2013 to March 2014), the admission prevalence of VRE was 2.41/100 patients and the mean incidence density of nosocomial cases was 2.61/1000 PD [P = 0.001 (pre- vs post-intervention)]. Thirteen nosocomial VRE infections were identified in the pre-intervention period, compared with one nosocomial VRE infection in the post-intervention period. Incidence densities of BSI pre- and post-intervention were 2.98 and 2.06/1000 PD (P = 0.15), respectively.

CONCLUSION

The epidemiology of emerging VRE appeared as a complex mix of admitted cases and transmissions in small clusters, challenging infection control measures. The implementation of universal octenidine-based bathing combined with a standardized washing regime led to a significant reduction in nosocomial VRE.

Bacterial contamination of open fractures - pathogens, antibiotic resistances and therapeutic regimes in four hospitals of the trauma network Cologne, Germany

INTRODUCTION

The bacterial contamination of soft tissues and bone in open fractures leads to an infection rate of up to 50%. Pathogens and their resistance against therapeutic agents change with time and vary in different regions. In this work, our aims were to characterize the bacterial spectrum present in open fractures, analyze the bacterial resistance to antibiotic agents and question the EAST guideline recommendations for antibiotic prophylaxis after open fractures in a German Trauma Network.

MATERIALS AND METHODS

We conducted a retrospective cohort study and included all patients with open fractures from 1(st) of January 2011 until the 31(st) of December 2014 in four hospitals of the trauma network cologne. Soft tissue damage was classified according to the Gustilo Anderson classification.

RESULTS

We included 123 patients. Forty-five injuries (37%) were classified I°, 45 (37%) as II° and 33 (27%) as III°. Lower leg (34%) was the most commonly injured location. An antibiotic prophylaxis was administered to 109 patients (89%). In 107 of them (98%) a cephalosporin or cephalosporin combination was given. In 35 of the patients (28%), microbiological samples were taken of the fracture site. Wound cultures were positive in 21 patients (60%). Fifty percent of the bacterial detections occurred in III° fractures. Coagulase negative Staphylococci (COST) were the most frequent pathogens. In II° open fractures one gram-negative strain was isolated. Fewest resistances were seen against quinolones and co-trimoxazole.

DISCUSSION

The recommended EAST guideline prophylaxis would have covered all but one bacterium (97% of positive cultures). One Escherichia coli was found in a II° open fracture and would have been missed. One of the isolated Staphylococci epidermidis and an Enterococcus faecium were resistant against gentamycin and first- and second-generation-cephalosporin's which were used as prophylaxis frequently. However, a regional adaption of the EAST guidelines seems not justified due to the rather low number of cases in our study.

CONCLUSION

The EAST guideline seems to be adequate in a high percentage of cases (97%) in the setting of the trauma network cologne. Further research should be guided at identification of initial open fracture pathogens to improve the efficiency of antibiotic prophylaxis.

Utility of two novel multiplexing assays for the detection of gastrointestinal pathogens - a first experience

BACKGROUND

Cause for gastroenteritis range from viral, bacterial to parasitic pathogens. Rapid Multiplexing techniques like ProGastro_SSCS and xTAG_GPP can detect broad panels of pathogens simultaneously. We performed a field test with a total number of 347 stool samples from adult hospitalized patients that were tested with the Luminex xTAG GPP assay; of the 157 samples positively tested for at least one pathogen by xTAG GPP a total number of 30 samples was retested with the ProGastro SSCS assay. Assays were compared to standard routine diagnostics.

FINDINGS

Multiplexing significantly reduced the time to the initial identification of a pathogen. Moreover, multiplexing detected pathogens for which a diagnostic assays was not requested by the physician and thus may be an important tool for avoiding nosocomial outbreaks.

CONCLUSION

This first frontline approach with these assays approves their utility compared to conventional microbiological methods.

Comparison of two commercial PCR methods for methicillin-resistant Staphylococcus aureus (MRSA) screening in a tertiary care hospital

Nose/throat-swabs from 1049 patients were screened for MRSA using CHROMagar MRSA, LightCycler Advanced MRSA, and Detect-Ready MRSA. Results were compared to the CHROMagar MRSA results, which was set as reference system. MRSA was detected in 3.05% of the patients with CHROMagar MRSA. LightCycler MRSA Advanced showed a higher clinical sensitivity (84.38%) than Detect-Ready MRSA (57.69%).The negative predictive values were high for both tests (>98%). The specificity and the positive predictive value were higher for the Detect-Ready MRSA test than for the LightCycler MRSA test (99.59% and 78.95% versus 98.52% and 64.29%). For routine screening LightCycler MRSA Advanced proved to be more efficient in our clinical setting as the clinical sensitivity was much higher than the sensitivity of Detect-Ready MRSA. CHROMagar MRSA detected more MRSA positive samples than both PCR methods, leading to the conclusion that the combination of PCR with cultural screening is still the most reliable way for the detection of MRSA. LightCycler MRSA Advanced was faster and needed less hands-on time. The advantage of Detect-Ready MRSA was the additional identification of methicillin-sensitive S.aureus (here in 34.63% of the samples), an information which can be possibly used for reducing the risk of postoperative infections in surgical patients in future.

Brain volume and diffusion markers as predictors of disability and short-term disease evolution in multiple sclerosis

BACKGROUND AND PURPOSE

MRI markers of neuroaxonal damage in MS have emerged as critical long-term predictors of MS-related disability. Here we investigated the potential of whole-brain diffusivity and brain volume for the prediction of cross-sectional disability and short- to medium-term clinical evolution.

MATERIALS AND METHODS

In this multimodal prospective longitudinal MRI study of 54 patients with MS (87% under immunomodulatory therapy, baseline and follow-up at a median of 12 months), ADC histogram analysis, WM lesion load, BPF, whole-brain atrophy rate, MSFC score, and EDSS score were obtained. A total of 44 patients with no relapse at both time points were included.

RESULTS

At both time points, ADC histogram analysis provided robust predictors of the MSFC scores (maximal R(2) = 0.576, P < .001), incorporated cognition and fine-motor skill subscores, and EDSS scores. Significant changes beyond physiologic age-related changes at follow-up were noted for ADC histogram markers and BPF. Stronger diffusivity alterations and brain volume at baseline predicted MSFC decline, as demonstrated by multiple linear regression analysis (mean ADC, R(2) = 0.203; P = .003) and lower baseline BPF in patients with declined compared with stable MSFC scores (P = .001). Results were independent of intercurrent relapses.

CONCLUSIONS

Diffusion histogram analysis provided stable surrogates of disability in MS and proved sensitive for monitoring disease progression during a median of 12 months. Advanced neuroaxonal pathology at baseline was indicative of an increased risk for sustained progression during a median of 12 months, independent of intercurrent relapses.

The TGF-β signaling modulators TRAP1/TGFBRAP1 and VPS39/Vam6/TLP are essential for early embryonic development

The pleiotropic cytokine transforming growth factor-β (TGF-β) signals through different pathways among which the Smad- and the MAP-Kinase pathways are already well characterized. Both pathways utilize adaptor/chaperone molecules that facilitate or modulate the intracellular signaling events. Two of the proteins shown in vitro to play a role in Smad-dependent signaling are the TGF-β Receptor Associated Protein-1 (TRAP1, also TGFBRAP1) and its homologue VPS39, also known as Vam6 and TRAP1-Like-Protein (TLP). We generated mice deficient for TRAP1 and VPS39/TLP, respectively. Absence of TRAP1 protein results in death at either of two defined timepoints during embryogenesis, before the blastula stage or during gastrulation, whereas most of the VPS39 deficient mice die before E6.5. Heterozygous mice show no overt phenotype. In summary, our data indicate that TRAP1 and VPS39 are nonredundant and essentially required for early embryonic development.

A set of novel multiplex Taqman real-time PCRs for the detection of diarrhoeagenic Escherichia coli and its use in determining the prevalence of EPEC and EAEC in a university hospital

Background

Accurate measurement of the incidence of diarrhoeagenic E. coli in patients with diarrhoea is hindered by the current methods of detection and varies from country to country. In order to improve the diagnosis of diarrhoeagenic E. coli (DEC), we developed a set of multiplex TaqMan real-time PCRs designed to detect the respective pathogens from an overnight stool culture.

Methods

Over the period Jan. 2006 to Dec. 2006 all stool specimens (n = 1981) received were investigated for EPEC and EAEC.

Results

Of these, 371 specimens had no growth of Enterobacteriaceae. Of the remaining 1610 specimens 144 (8,9%) were positive for EPEC and 78 (4,8%) positive for EAEC. Among the EPEC positive stool specimens 28 (19,4%) were received from the tropical diseases unit, 49 (34%) from the paediatric dept. and 67 (46,5%) from the remainder of the wards. The EAEC were distributed as follows: 39 (50%) - tropical diseases, 19 (24,4%) -paediatrics and 20 (25,6%) other wards. Proportionately more EAEC and EPEC were found in children less than 3 years of age than other age groups. In only 22,2% of the detected EPEC and 23% of EAEC was the investigation requested by hospital staff.

Conclusions

This is, to our knowledge, the first study using a multiplex TaqMan PCR for the successful detection of diarrhoeagenic E. coli. In conclusion, due to the high prevalence of DEC detected, investigation of EPEC and EAEC should be recommended as a routine diagnostic test for patients with infectious diarrhoea.

Comprehensive study on the occurrence and distribution of pathogenic microorganisms carried by synanthropic flies caught at different rural locations in Germany

In the current study, samples of 50 synanthropic flies were collected from each of five rural locations used for domestic animal husbandry (specifically a cattle barn, a dog pound, a horse stable, and a pigpen). Flies were examined using a variety of microbiological methods to determine the pathogenic agents that they carried. The most frequently sampled species were Musca domestica (L.) (51%) followed by Stomoxys calcitrans (L.) (24%). All fly species were found to carry an array of different pathogenic bacterial and fungal species. Among these were human pathogens such as Campylobacter jejuni and Escherichia coli-strains (EHEC, EPEC, and ETEC) and the fungi Candida albicans and Candida tropicalis. The germs could be detected in the intestines as well as on the exoskeletons of the flies. The current study confirms and supplements the general knowledge about pathogens that may be transmitted to domestic animals and humans by synanthropic flies.

Pilot study on synanthropic flies (e.g. Musca, Sarcophaga, Calliphora, Fannia, Lucilia, Stomoxys) as vectors of pathogenic microorganisms

In the present study, different fly species were associated with foodborne and other pathogens. Wild synanthropic flies belonging to 12 species of 12 genera were caught for the isolation and identification of microorganisms, which might have been possibly transmitted by these flies. Trapping of flies was done at different domestic animal related places (dog pound, poultry house, cattle barn, horse stable, pigpen). All 56 individual flies were shown to be carriers of multiple species of microorganisms. Furthermore, the capacity for the flies to act as vectors was demonstrated by successful transfer of the microorganisms from live flies to blood agar plates. Potentially pathogenic and several non-pathogenic microorganisms were found. Among them, a series of pathogenic Escherichia coli strains (EAEC, EPEC, ETEC) was identified. This is the first study to clearly demonstrate the potential of these flies as vectors for the transmission of pathogenic microorganisms.