Fluorescence In Situ Hybridization as Diagnostic Tool for Implant-associated Infections: A Pilot Study on Added Value

Implant-associated infections are a devastating complication in surgery. Especially in infections with biofilm-forming microorganisms, the identification of the causing microorganism remains a challenge. However, the classification as biofilm is not possible with conventional polymerase chain reaction or culture-based diagnostics. The aim of this study was to evaluate the additional value of fluorescence in situ hybridization (FISH) and nucleic acid amplification technique (FISHseq) to discuss a diagnostic benefit of the culture-independent methods and to map spatial organization of pathogens and microbial biofilms in wounds.

Methods

In total, 118 tissue samples from 60 patients with clinically suspected implant-associated infections (n = 32 joint replacements, n = 24 open reduction and internal fixation, n = 4 projectiles) were analyzed using classic microbiological culture and culture-independent FISH in combination with polymerase chain reaction and sequencing (FISHseq).

Results

In 56 of 60 wounds, FISHseq achieved an added value. FISHseq confirmed the result of cultural microbiological examinations in 41 of the 60 wounds. In 12 wounds, one or more additional pathogens were detected by FISHseq. FISHseq could show that the bacteria initially detected by culture corresponded to a contamination in three wounds and could exclude that the identified commensal pathogens were a contamination in four other wounds. In five wounds, a nonplanktonic bacterial life form was detected.

Conclusions

The study revealed that FISHseq gives additional diagnostic information, including therapy-relevant findings that were missed by culture. In addition, nonplanktonic bacterial life forms could also be detected with FISHseq, albeit less frequently than previously indicated.

Molecular Epidemiology of Multidrug-Resistant Bacteria Isolated from Libyan and Syrian Patients with War Injuries in Two Bundeswehr Hospitals in Germany

Introduction

We assessed the molecular epidemiology of multidrug-resistant bacteria colonizing or infecting war-injured patients from Libya and Syria who were treated at the Bundeswehr hospitals Hamburg and Westerstede, Germany.

Methods

Enterobacteriaceae and Gram-negative rod-shaped nonfermentative bacteria with resistance against third-generation methoxyimino cephalosporins or carbapenems as well as methicillin-resistant Staphylococcus aureus (MRSA) from war-injured patients from Libya and Syria were assessed by molecular typing, i.e., spa typing for MRSA strains and rep-PCR and next-generation sequencing (NGS) for Gram-negative isolates.

Results

A total of 66 isolates were assessed – comprising 44 Enterobacteriaceae, 16 nonfermentative rod-shaped bacteria, and 6 MRSA from 22 patients – and 8 strains from an assessment of the patient environment comprising 5 Enterobacteriaceae and 3 nonfermentative rod-shaped bacteria. Although 24 out of 66 patient strains were isolated more than 3 days after hospital admission, molecular typing suggested only 7 likely transmission events in the hospitals. Identified clonal clusters primarily suggested transmission events in the country of origin or during the medical evacuation flights.

Conclusions

Nosocomial transmissions in hospital can be efficiently prevented by hygiene precautions in spite of heavy colonization. Transmission prior to hospital admission like on evacuation flights or in crises zones needs further assessment.

[Acute therapeutic measures for limb salvage Part 2 : Debridement, lavage techniques and anti-infectious strategies]

The quality of the primary care of Gustilo-Anderson (GA) type IIIB and IIIC extremity injuries is crucial to the success of the limb salvage procedure. This article provides a compilation of consistent, but often controversially discussed aspects of initial debridement, modern techniques of lavage and wound closure, in addition to current issues on the application of antibiotics and antiseptics, based on our own experiences and the latest literature. The following points should be stressed. Severe extremity injuries with gross contamination (GA IIIA, B, and C) will still be associated with an infection rate of up to 60 %. The initial debridement should be performed as soon as an experienced trauma surgeon is available. Tissue that is definitely avital will have to be removed, whereas traumatized but potentially surviving tissue will have to be re-evaluated during a second-look operation after 36-48 h. Given a high enough level of contamination, biofilms will form after as few as 6 h. The perioperative antibiotic prophylaxis has to be initiated early and should be continued for at least 24 h (GA I/II) or up to 5 days (GA III). In cases of bacterial contamination, wound irrigation will be useful with additives such as polyhexanide, octenidine or superoxidized water. Rinsing of the wound should be performed with 3-9 L and only slight manual pressure (no jet lavage). The definitive primary closure of a wound should be achieved in the initial operation, but only in the case of certain "decontamination" and overall vitality of the wound (GA I and II). In the presence of high-grade injuries, a temporary vacuum sealing technique can be used until the earliest possible definitive plastic surgical wound closure.

Food-borne norovirus-outbreak at a military base, Germany, 2009

BACKGROUND

Norovirus is often transmitted from person-to-person. Transmission may also be food-borne, but only few norovirus outbreak investigations have identified food items as likely vehicles of norovirus transmission through an analytical epidemiological study.During 7-9 January, 2009, 36 persons at a military base in Germany fell ill with acute gastroenteritis. Food from the military base's canteen was suspected as vehicle of infection, norovirus as the pathogen causing the illnesses. An investigation was initiated to describe the outbreak's extent, to verify the pathogen, and to identify modes of transmission and source of infection to prevent further cases.

METHODS

For descriptive analysis, ill persons were defined as members of the military base with acute onset of diarrhoea or vomiting between 24 December 2008, and 3 February 2009, without detection of a pathogen other than norovirus in stools. We conducted a retrospective cohort study within the headquarters company. Cases were military base members with onset of diarrhoea or vomiting during 5-9 January. We collected information on demographics, food items eaten at the canteen and contact to ill persons or vomit, using a self-administered questionnaire. We compared attack rates (AR) in exposed and unexposed persons, using bivariable and multivariable logistic regression modelling. Stool specimens of ill persons and canteen employees, canteen food served during 5-7 January and environmental swabs were investigated by laboratory analysis.

RESULTS

Overall, 101/815 (AR 12.4%) persons fell ill between 24 December 2008 and 3 February 2009. None were canteen employees. Most persons (n = 49) had disease onset during 7-9 January. Ill persons were a median of 22 years old, 92.9% were male. The response for the cohort study was 178/274 (72.1%). Of 27 cases (AR 15.2%), 25 had eaten at the canteen and 21 had consumed salad. Salad consumption on 6 January (aOR: 8.1; 95%CI: 1.5-45.4) and 7 January (aOR: 15.7; 95%CI: 2.2-74.1) were independently associated with increased risk of disease.Norovirus was detected in 8/28 ill persons' and 4/25 canteen employees' stools, 6/55 environmental swabs and 0/33 food items. Sequences were identical in environmental and stool samples (subtype II.4 2006b), except for those of canteen employees. Control measures comprised cohort isolation of symptomatic persons, exclusion of norovirus-positive canteen employees from work and disinfection of the canteen's kitchen.

CONCLUSIONS

Our investigation indicated that consumption of norovirus-contaminated salad caused the peak of the outbreak on 7-9 January. Strict personal hygiene and proper disinfection of environmental surfaces remain crucial to prevent norovirus transmission.