Magda Diab-Elschahawi

Bacterial growth kinetic without the influence of the immune system using vacuum-assisted closure dressing with and without negative pressure in an in vitro wound model.

The physical capacity of negative pressure wound therapy (NPWT) dressing on the bacterial growth in an in vitro wound model was investigated. Standardised wounds were contaminated with a clinical Staphylococcus aureus strain and incubated at 35°C for 6 hours. Four wounds were treated with continuous negative pressure (125 mmHg) and four controls without. Bacterial load per gram tissue and per gram polyurethane sponge were measured after 24, 36 and 72 hours. Without negative pressure, the initial mean S. aureus load per gram tissue was 1·42 × 104, with negative pressure 1·84 × 104, P = 0·294. After 24, 36 and 72 hours, both models yielded comparable numbers of organisms (24 hours: P = 0·081; 48 hours: P = 0·455; 72 hours: P = 0·825, respectively). Bacterial load of sponges with or without negative pressure also did not differ. Over a period of 72 hours, sponges with negative pressure yielded 1·60 × 108, those without negative pressure yielded 1·74 × 108 CFU/g sponge (P = 0·876). In non vital tissue without the influence of the immune system, the bacterial load did not decrease in our in vitro model using an NPWT dressing. This observation was independent of the physical effect of continuous negative pressure at 125 mmHg. The reduction in bacteria demonstrated in previous studies appears to be caused by other effects than physical suction alone. However, the results obtained are limited as non viable tissue was used and the effect of suction on dead tissue might be very different from that occurring on perfused tissue, for example, in an animal model or in patients.

Microsatellite Genotyping Clarified Conspicuous Accumulation of Candida parapsilosis at a Cardiothoracic Surgery Intensive Care Unit

ABSTRACT Candida parapsilosis has become a significant cause of invasive fungal infections in seriously ill patients. Nosocomial outbreaks through direct and indirect contact have been described. The aim of this study was the molecular characterization of what appeared to be an ongoing C. parapsilosis outbreak at the cardiothoracic intensive care unit of the University Hospital of Vienna between January 2007 and December 2008. Using two different molecular typing methods—automated repetitive sequence-based PCR (DiversiLab; bioMérieux) and microsatellite genotyping—we investigated the genetic relationship of 99 C. parapsilosis isolates. Eighty-three isolates originated from the cardiothoracic intensive care unit, while 16 isolates were random control isolates from other intensive care units and a different Austrian hospital. The 99 C. parapsilosis isolates analyzed by repetitive-element PCR all showed identical genotypes, suggesting an ongoing outbreak. In contrast, microsatellite genotyping showed a total of 56 different genotypes. Two major genotypes were observed in 10 and 15 isolates, respectively, whereas another 13 genotypes were observed in 2 to 4 isolates each. Forty-one genotypes were observed only once. Closely related genotypes that differed in only a single microsatellite marker were grouped into clonal complexes. When it comes to C. parapsilosis, microsatellite genotyping is a more discriminative method than repetitive-element PCR genotyping to investigate outbreaks.

Severe Clostridium difficile infection: incidence and risk factors at a tertiary care university hospital in Vienna, Austria

SummaryBackgroundClostridium difficile infection (CDI) is the major cause of hospital-acquired bacterial diarrhoea. The incidence of CDI has been increasing in Canada, the US and Europe and severe cases are becoming more common.MethodsA retrospective cohort study investigating all patients with an episode of CDI present at the Vienna University Hospital between 01 January 2012 and 31 December 2012 was conducted. All microbiologically confirmed C. difficile toxin positive cases were included, ribotyped and analysed regarding their clinical course.ResultsA total of 278 patients with CDI were recorded, with an overall CDI incidence of 5.23 per 10,000 patients-days. Around 84,5u2009% (235/278) of CDI cases would have been classified as severe CDI according to European Society of Clinical Microbiology and Infectious Diseases (ESCMID) if all criteria were used. According to Society for Healthcare Epidemiology of America and the Infectious Diseases Society of America (SHEA/IDSA) guidelines only 16.5u2009% (46/278) could be classified as severe; with a severe CDI incidence of 4.41 and 0.86 per 10,000 patient-days, respectively. Multivariate analysis showed only a co-morbidity index of ≥u20093 (pu2009=u20090.013) as independent risk factor for severe CDI. No link between ribotypexa0027 and severity or clustering was observed in our study population.ConclusionsSpecial attention in terms of restrictive antibiotic prescription should be given to patients having a Charlson co-morbidity ≥u20093 at the time of hospital admission. SHEA/IDSA guidelines were more accurate than ESCMID criteria in predicting severe CDI in our collective, of mostly severely ill patients, in a tertiary care hospital setting.ZusammenfassungGrundlagenClostridium difficile ist zu einem der wichtigsten nosokomialen Erreger infektiöser Diarrhoe in Industriestaaten geworden. In Canada, den USA und Europa findet sich eine rasch steigende Inzidenz von C. difficile Infektionen (CDI) und mit dieser ein Anstieg von schweren Erkrankungsverläufen.MethodikVon 1. Jänner bis 31. Dezember 2012 wurden im Rahmen einer retrospektiven Kohortenstudie im Allgemeinen Krankenhaus der Stadt Wien – Medizinische Universitätsklinik alle mikrobiologisch gesicherten C. difficile Toxin positive Fälle eingeschlossen, ribotypisiert und ihr klinischer Verlauf analysiert.ErgebnisseInsgesamt wurden 278 PatientInnen mit CDI in die Studie aufgenommen. Es zeigte sich eine Gesamt-CDI Inzidenz von 5,23 pro 10.000 PatientInnentagen. Ein schwerer CDI Verlauf fand sich bei 84,5u2009% (235/278) der CDI Fällen, wenn die European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Kriterien angewandt wurden. Zieht man die Kriterien der Society for Healthcare Epidemiology of America and the Infectious Diseases Society of America (SHEA/IDSA) heran, so konnten nur 16,5u2009% (46/278) der CDI Fälle als schwer charakterisiert werden. Dies entspricht einer jeweiligen Inzidenz an schweren CDI Fälle von 4,41 und 0,86 pro 10.000 PatientInnentage nach ESCMID und SHEA/IDSA. Multivariate Analysen zeigten nur einen Co- Morbiditätsindex vonu2009≥u20093 (pu2009=u20090,013) als unabhängiger Risikofaktor für eine schwere CDI. In dieser Studienpopulation konnte kein Zusammenhang zwischen dem „hypervirulenten“ Ribotyp 027 und Schwere oder Clustering beobachtet werden.SchlussfolgerungenBei PatientInnen, die bereits bei der Aufnahme einen Charlson Co-Morbiditätsindex vonu2009≥u20093 haben, sollte die Notwendigkeit jedes Antibiotika Einsatzes besonders kritisch abgewogen werden. SHEA/IDSA Kriterien führten zu einer strikteren Einteilung schwerer CDI Fälle als die europäischen ESCMID Kriterien in unserem Patientenkollektiv an der Universitätsklinik Wien.

Effectiveness of preventive measures for hemato-oncologic patients undergoing stem cell transplantation during a period of hospital construction

BACKGROUNDnAspergillus spp are ubiquitous spore-forming fungi. Construction work, renovation, demolition, or excavation activities within a hospital or in surrounding areas increase the risk for aspergillus infection in susceptible patients and are the main cause of nosocomial aspergillus outbreaks.nnnMETHODSnWe investigated the efficacy of infection control measures on the frequency of fungal infection among hemato-oncologic patients undergoing stem cell transplantation during excavation and construction work of an adjacent hospital building. Clinical isolates from these patients obtained before and during the excavation and construction period were analyzed. Preventive measures consisted in the implementation of a multibarrier concept to protect these patients from fungal infection.nnnRESULTSnThere was no record of any clinical isolate of Aspergillus spp in the observation period before the beginning of the groundwork. However, 3 clinically significant isolates of Aspergillus spp were detected in respiratory tract specimen of 2 patients after the beginning of excavation and demolition work, which were found to be community acquired.nnnCONCLUSIONnAlthough our data cannot demonstrate the efficacy of infection control measures during construction work, it can be concluded that excavation work close to immunocompromised patients is safe if a bundle of preventive measures is implemented before groundwork.

Microbiologic surveillance of duodenoscope reprocessing at the Vienna University Hospital from November 2004 through March 2015.

Bacterial contamination of duodenoscopes is attributed to difficulties with reprocessing the Albarran lever. Routine microbiologic surveillance data of endoscopes with Albarran lever retrospectively collected from November 2004 through March 2015 revealed no growth of microorganism at this specific site. Transmission of endoscope-associated infection is avoidable by following validated reprocessing procedures.

Successful implementation of infection control strategies prevents P. aeruginosa transmission among cystic fibrosis patients inside the hospital

Background: The aim of this study was to characterise the epidemiology of P. aeruginosa isolated from cystic fibrosis (CF) patients at the Vienna General Hospital (VGH) by molecular genetic fingerprinting in order to understand transmission ways and to evaluate the established infection control protocols. Methods: The outpatient clinic for CF patients at the VGH cares for children and adolescents up to the age of 18 years. Among an average of 139 patients cared for at the clinic, 41 were tested positive for P. aeruginosa during the study period. Fifty P. aeruginosa isolates, obtained between August 2010 and March 2012 from routine examinations of CF patients, were subject to molecular characterization using the DiversiLab® method. Results: 42 distinguishable molecular-biological patterns were identified, 7 of which were found multiple times. 40 out of 42 genotypes were retrieved from single patients only, while two patterns were present in two patients each. Nine patients presented with two or more phenotypically diverse P. aeruginosa isolates. In five of these cases the retrieved isolates belonged to the same genotype. Conclusion: The broad genetic heterogeneity of P. aeruginosa in the studied patient population suggests that the majority of CF patients cared for at the VGH acquire P. aeruginosa from environmental sources. It may be concluded that implemented infection control guidelines have been successful in preventing nosocomial transmission of P. aeruginosa among CF patients within the VGH and patient-to-patient transmission outside the hospital. Chronic polyclonal infection/colonization was rare in the study population.

The strength of coughing may forecast the likelihood of spread of multi-drug resistant microorganisms from the respiratory tract of colonized patients

BackgroundCurrent recommendations indicate that patients who are coughing and have multidrug resistant microorganisms (MDROs) in their sputum are considered to be shedders and should be cared for in single room isolation at least until symptoms resolve. Airborne spread and subsequent contamination of surfaces adjacent to patients may contribute to transmission. Hence, isolation measures for patients colonized or infected with MDRO at their respiratory tract are intended to interrupt such transmission. However, the potential for microbial shedding in patients with MDRO-positive microbiological reports from their respiratory tract and factors justifying the need for single room isolation are viewed controversially.MethodsCough aerosol produced by patients colonized with MDROs was measured for viable counts. Descriptive analysis together with logistic regression analysis was performed to assess the impact of strength of cough on growth of MDRO on culture plates.ResultsIn 18% (23/128) MDRO were transmitted. Multivariate analysis revealed that strength of cough significantly predicts the yield of MDRO on culture plates (Pu2009=u20090.012).ConclusionBased on these results it can be concluded that risk stratification for decision of single room isolation of patients colonized or infected with MDROs at their respiratory tract may also take the severity of cough into consideration. However, more work is required in order to assess the severity of cough objectively.