Since December 2019, the world has been in the grip of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the disease it causes, coronavirus disease 2019 (COVID-19).¹ On February 27, 2020, the first patient with COVID-19 was detected in the Netherlands, after a trip to northern Italy between February 18, 2020, and February 21, 2020.² From then until March 6, 2020, another 127 COVID-19 cases were identified in the Netherlands, including 9 health care workers (HCWs) in 2 Dutch teaching hospitals in the southern part of the Netherlands who received a diagnosis of COVID-19 between March 2, 2020, and March 6, 2020. Eight of these 9 HCWs had no history of travel to China or northern Italy, raising the question of whether undetected community circulation was occurring. Because these findings coincided with the seasonal influenza peak³ and because SARS-CoV-2 infection in HCWs could lead to both sick leave and introduction of the virus into the hospital, this finding prompted a demand for testing HCWs. After initial observations of SARS-CoV-2 detection in persons with mild symptoms who did not meet the definition for case finding,¹ screening for SARS-CoV-2 was implemented to determine the prevalence and the clinical presentation of COVID-19 among HCWs with self-reported fever or respiratory symptoms in these 2 hospitals.

Molecular typing has become indispensable in the detection of nosocomial transmission of bacterial pathogens and the identification of sources and routes of transmission in outbreak settings, but current methods are labor-intensive, are difficult to standardize, or have limited resolution. Whole-genome multilocus sequence typing (wgMLST) has emerged as a whole-genome sequencing (WGS)-based gene-by-gene typing method that may overcome these limitations and has been applied successfully for several species in outbreak settings. In this study, genus-, genetic-complex-, and species-specific wgMLST schemes were developed for Citrobacter spp., the Enterobacter cloacae complex, Escherichia coli , Klebsiella oxytoca , and Klebsiella pneumoniae and used to type a national collection of 1,798 extended-spectrum-beta-lactamase-producing Enterobacteriaceae (ESBL-E) isolates obtained from patients in Dutch hospitals. Genus-, genetic-complex-, and species-specific thresholds for genetic distance that accurately distinguish between epidemiologically related and unrelated isolates were defined for Citrobacter spp., the E. cloacae complex, E. coli , and K. pneumoniae . wgMLST was shown to have higher discriminatory power and typeability than in silico MLST. In conclusion, the wgMLST schemes developed in this study facilitate high-resolution WGS-based typing of the most prevalent ESBL-producing species in clinical practice and may contribute to further elucidation of the complex epidemiology of antimicrobial-resistant Enterobacteriaceae . wgMLST opens up possibilities for the creation of a Web-accessible database for the global surveillance of ESBL-producing bacterial clones.

This study evaluated the added value of selective preenrichment for the detection of rectal carriage of extended-spectrum-beta-lactamase-producing Enterobacteriaceae (ESBL-E). ESBL-E rectal carriage was identified in 4.8% of hospitalized patients, and 25.9% of ESBL-E rectal carriers were identified with selective preenrichment only.

Background: On February 27, 2020, the first patient with COVID-19 was reported in the Netherlands. During the following weeks, nine healthcare workers (HCWs) were diagnosed with COVID-19 in two Dutch teaching hospitals, eight of whom had no history of travel to China or Northern-Italy. A low-threshold screening regimen was implemented to determine the prevalence and clinical presentation of COVID-19 among HCWs in these two hospitals. Methods: HCWs who suffered from fever or respiratory symptoms were voluntarily tested for SARS-CoV-2 by real-time reverse-transcriptase PCR on oropharyngeal samples. Structured interviews were conducted to document symptoms for all HCWs with confirmed COVID-19. Findings: Thirteen-hundred fifty-three (14%) of 9,705 HCWs employed were tested, 86 (6%) of whom were infected with SARS-CoV-2. Most HCWs suffered from relatively mild disease and only 46 (53%) reported fever. Eighty (93%) HCWs met a case definition of fever and/or coughing and/or shortness of breath. None of the HCWs identified through the screening reported a travel history to China or Northern Italy, and 3 (3%) reported to have been exposed to an inpatient known with COVID-19 prior to the onset of symptoms. Interpretation: Within two weeks after the first Dutch case was detected, a substantial proportion of HCWs with fever or respiratory symptoms were infected with SARS-CoV-2, probably caused by acquisition of the virus in the community during the early phase of local spread. The high prevalence of mild clinical presentations, frequently not including fever, asks for less stringent use of the currently recommended case-definition for suspected COVID-19. RESEARCH IN PERSPECTIVE: Evidence before this study: This study was conducted in response to the global spread of SARS-CoV-2, and the detection of eight healthcare workers (HCWs) in two Dutch teaching hospitals within two weeks after the first patient with COVID-19 was detected in the Netherlands who had no history of travel to China or Northern-Italy, raising the question of whether undetected community circulation was occurring. Added value of this study: To the best of our knowledge, this report is the first to describe the prevalence, the clinical presentation and early outcomes of COVID-19 in HCWs, which may be helpful for others seeking to identify HCWs suspected for COVID-19 in an outbreak situation. Implications of all the available evidence: We describe that within two weeks after the first Dutch case was detected, a substantial proportion of HCWs with fever or (mild) respiratory symptoms were infected with SARS-CoV-2, probably caused by acquisition of the virus in the community during the early phase of local spread. The high prevalence of mild clinical presentations, frequently not including fever, asks for less stringent use of the currently recommended case-definition for suspected COVID-19.

Background. The use of antibiotics in food production selects for resistant bacteria and may cause a threat to human and animal health. Belgium and the Netherlands have one of the highest densities of broilers and pigs in Europe, making active monitoring of antibiotic use and resistance in this region vital. Objectives. This study aimed to quantify ESBL-producing (ESBL-E. coli), carbapenem- and ciprofloxacin-resistant (CiproR) Escherichia coli in animal feces on broiler and pig farms with a history of high antibiotic use in Belgium and the Netherlands. Methods. A total of 779 broiler and 817 pig fecal samples, collected from 29 conventional broiler and 31 multiplier pig farms in the cross-border region of Belgium and the Netherlands, were screened for the presence of antibiotic-resistant E. coli using selective culturing. Results. Carbapenem-resistant E. coli were not detected. ESBL-E. coli were remarkably more prevalent in samples from Belgian than Dutch farms. However, CiproR-E. coli were highly prevalent in broilers of both countries. The percentage of samples with ESBL- and CiproR-E. coli was lower in pig compared to poultry farms and varied between farms. No clear association with the on-farm antibiotic use in the year preceding sampling was observed. Multidrug resistance was frequently observed in samples from both countries, but ESBL-production in combination with ciprofloxacin resistance was higher in samples from Belgium. Conclusions. This study demonstrated marked differences in antibiotic resistance between countries, farms and within farms. The observed variation cannot be explained straightforward by prior quantity of antibiotic use suggesting that it results from more complex interactions that warrant further investigation.