A spatiotemporal simulation study on the transmission of harmful microorganisms through connected healthcare workers in a hospital ward setting.

BACKGROUND: Hand transmission of harmful microorganisms may lead to infections and poses a major threat to patients and healthcare workers in healthcare settings. The most effective countermeasure against these transmissions is the adherence to spatiotemporal hand hygiene policies, but adherence rates are relatively low and vary over space and time. The spatiotemporal effects on hand transmission and spread of these microorganisms for varying hand hygiene compliance levels are unknown. This study aims to (1) identify a healthcare worker occupancy group of potential super-spreaders and (2) quantify spatiotemporal effects on the hand transmission and spread of harmful microorganisms for varying levels of hand hygiene compliance caused by this group. METHODS: Spatiotemporal data were collected in a hospital ward of an academic hospital using radio frequency identification technology for 7 days. A potential super-spreader healthcare worker occupation group was identified using the frequency identification sensors' contact data. The effects of five probability distributions of hand hygiene compliance and three harmful microorganism transmission rates were simulated using a dynamic agent-based simulation model. The effects of initial simulation assumptions on the simulation results were quantified using five risk outcomes. RESULTS: Nurses, doctors and patients are together responsible for 81.13% of all contacts. Nurses made up 70.68% of all contacts, which is more than five times that of doctors (10.44%). This identifies nurses as the potential super-spreader healthcare worker occupation group. For initial simulation conditions of extreme lack of hand hygiene compliance (5%) and high transmission rates (5% per contact moment), a colonised nurse can transfer microbes to three of the 17 healthcare worker or patients encountered during the 98.4 min of visiting 23 rooms while colonised. The harmful microorganism transmission potential for nurses is higher during weeknights (5 pm - 7 am) and weekends as compared to weekdays (7 am - 5 pm). CONCLUSION: Spatiotemporal behaviour and social mixing patterns of healthcare can change the expected number of hand transmissions and spread of harmful microorganisms by super-spreaders in a closed healthcare setting. These insights can be used to evaluate spatiotemporal safety behaviours and develop infection prevention and control strategies.

The added value of hepatitis E diagnostics in determining causes of hepatitis in routine diagnostic settings in the Netherlands.

OBJECTIVES: Hepatitis E virus (HEV) genotype 3 is endemic in Europe and an underdiagnosed and emerging (public) health issue. In recent years commercial enzyme immunoassays (EIAs) that detect antibodies to HEV more adequately, became available. We investigated the added value of this HEV serology in the diagnostic work flow to detect viral causes of recent hepatitis. METHODS: During a 2-year period (May 2013 to May 2015), HEV serology was added to the hepatitis work flow, consisting of serological detection of hepatitis viruses A, B and C (HAV, HBV, HCV), Epstein-Barr virus (EBV) and cytomegalovirus (CMV). Samples positive for HEV IgM were also analysed using PCR to detect HEV RNA. If positive, HEV sequencing was performed for genotyping purposes. RESULTS: In 235 out of 2521 patients (9.3%), a viral cause for hepatitis was found. Recent HAV, HBV, HCV, EBV or CMV infections were serologically diagnosed in 3, 34, 10, 69 and 42 patients, respectively. Seventy-eight patients (3.1%) had a recent HEV infection. In 49 of them, sufficient HEV RNA was present for genotyping. All patients were infected with HEV genotype 3. CONCLUSIONS: In our region, an HEV infection is the most frequently diagnosed viral cause for recent hepatitis. These results indicate that, in a country where HEV is endemic, serological HEV diagnostics should be added to the standard work-up for viral hepatitis.

Axillary recurrence after sentinel lymph node biopsy.

UNLABELLED: Sentinel lymph node biopsy (SLNB) without further axillary dissection in patients with sentinel node-negative breast carcinoma appears to be a safe procedure to ensure locoregional control. During a median follow-up of 35 months the false-negative rate was 1% in our study population of 185 patients. BACKGROUND: The objective of this prospective study is to provide data on follow-up of patients with primary operable breast carcinoma staged with SLNB without axillary lymph node dissection (ALND) if the sentinel lymph nodes (SLNs) were tumour-negative. METHODS: One hundred and eighty-five patients were enrolled. Preoperative dynamic and static lymphoscintigraphy were performed; both a vital blue dye and a gamma detection probe were used intraoperatively. Patients with tumour-positive SLNs received completion ALND or if no SLNs could be identified. All patients were monitored according to regional follow-up protocols. RESULTS: The SLNs were identified in 179 out of the 185 patients. In 73 patients the SLNs were tumour-positive and in 106 patients tumour-negative. The median follow-up was 35 months (range 17-59). In one SLN-negative patient an axillary recurrence occurred 26 months after the SLNB (false-negative rate: 1%). CONCLUSIONS: SLNB without ALND appears to be a safe procedure to ensure locoregional control in SLN-negative breast carcinoma, if carried out by an experienced team.

Is sentinel node biopsy beneficial in melanoma patients? A report on 200 patients with cutaneous melanoma.

AIM: The aim of this study was to evaluate the reliability and clinical impact of sentinel node biopsy, including preoperative lymphoscintigraphy and intraoperative lymphatic mapping in patients with cutaneous melanoma of the head, neck, trunk or extremities. METHODS: Two hundred patients (103 women, 97 men), median age 57 (range 21-86) years with cutaneous melanoma > or =1.0mm Breslow thickness and clinically negative lymph nodes participated in a single institutional prospective study from May 1995 to January 2000. Primary melanoma sites included: 22 head and neck (11%), 67 trunk (34%), 29 upper extremity (14%) and 82 lower extremity (41%). The median Breslow thickness was 2.5 (range 1.0-20.0)mm. Preoperative dynamic and static lymphoscintigraphy, intraoperative blue dye and a gamma detection probe were used. If histological examination with HE or IHC showed metastases, therapeutic lymph node dissection (TLND) was performed. RESULTS: Sentinel node(s) could be identified in 197 patients (99%); 393 sentinel nodes (mean: 2.0 per patient, range 1-7) were removed from 241 basins. Three procedures failed in the head and neck region. In 167 patients, the sentinel nodes were both blue and radioactive (85%); in 26 patients, they were only radioactive (13%) and in four patients only blue (2%). In total, 150 patients had tumour-negative sentinel nodes (76%). During a median follow-up of 47 (range 24-79) months, nodal recurrence in a negative mapped basin was documented in six patients of which isolated recurrence was in two patients and recurrence together with locoregional recurrence in four patients (false negative rate 6/54=11%). Estimated three-year recurrence-free survival in the node-negative patients and node-positive patients was 83 and 66% respectively (P<0.05). The overall survival at three years was 92 and 73% respectively (P<0.05). CONCLUSION: Sentinel node biopsy provides accurate staging and important prognostic information. The final place of sentinel node biopsy is still undefined, and therefore sentinel node biopsy is still considered as an experimental surgical staging procedure.