Katrin Gaardbo Kuhn

A waterborne outbreak with a single clone of Campylobacter jejuni in the Danish town of Køge in May 2010

Abstract Background: In Denmark, large-scale waterborne outbreaks are rare. This report describes the investigation of an outbreak that occurred in the town of Køge in May 2010. Methods: The epidemiological investigation consisted of hypothesis generating telephone interviews, followed by a cohort study among approximately 20,000 residents using an online questionnaire. Odds ratios were calculated for exposures including the number of glasses of tap water consumed. Geographical spreading was assessed using a geographical information system. The microbiological investigation included cultures of stool samples and flagellin-typing. In the environmental investigation, water samples were tested for Escherichia coli and coliform counts and for DNA of Campylobacter, Enterococcus, and Bacteroides. During the outbreak investigation a water boiling order was enforced, as tap water was considered a potential source. Results: Of 45 patients with laboratory confirmed Campylobacter infection in the municipality of Køge in May, 43 lived in the area covered by the central water supply. Of 61 patients with laboratory confirmed Campylobacter jejuni by 8 June, 50 shared a common flagellin gene type – flaA type 36 (82%). The epidemic curve from the cohort study showed a wave of diarrhoea onset from 14 to 20 May (n = 176). Among these patients, the development of diarrhoea was associated with drinking tap water with a dose–response pattern (linear increase by 2 glasses: odds ratio 1.40, 95% confidence interval 1.16–1.70). No bacterial DNA was found in water samples. Conclusions: These findings indicated a point source contamination of tap water with a single clone of C. jejuni which likely occurred on 12–13 May. The water boiling order was lifted on 18 June.

Detecting non-typhoid Salmonella in humans by ELISAs: a literature review.

Non-typhoid salmonellosis is one of the most common causes of foodborne illness throughout the world. Serological methods for the diagnosis of Salmonella infections vary widely and the most commonly used test is limited by high running costs as well as low sensitivity and specificity. Fast and reliable immunoassays which detect subunit antigens for Salmonella enterica subsp. enterica serovar Typhi are commercially available but at present there is no international consensus on similar tests for non-typhoid salmonellosis. In contrast to the veterinary and food sectors, most immunoassays for non-typhoid human Salmonella diagnosis are developed in-house and used in-house for research or surveillance purposes, rather than for routine diagnostics. Considering the current burden of disease, the development of a validated and standardized, commercially available antibody assay for diagnosing non-typhoid human salmonellosis could be of great benefit for diagnostic and surveillance purposes throughout the world.

Gastrointestinal Illness among Triathletes Swimming in Non-Polluted versus Polluted Seawater Affected by Heavy Rainfall, Denmark, 2010-2011

Recent years have seen an increase in the frequency of extreme rainfall and subsequent flooding across the world. Climate change models predict that such flooding will become more common, triggering sewer overflows, potentially with increased risks to human health. In August 2010, a triathlon sports competition was held in Copenhagen, Denmark, shortly after an extreme rainfall. The authors took advantage of this event to investigate disease risks in two comparable cohorts of physically fit, long distance swimmers competing in the sea next to a large urban area. An established model of bacterial concentration in the water was used to examine the level of pollution in a spatio-temporal manner. Symptoms and exposures among athletes were examined with a questionnaire using a retrospective cohort design and the questionnaire investigation was repeated after a triathlon competition held in non-polluted seawater in 2011. Diagnostic information was collected from microbiological laboratories. The results showed that the 3.8 kilometer open water swimming competition coincided with the peak of post-flooding bacterial contamination in 2010, with average concentrations of 1.5x104 E. coli per 100 ml water. The attack rate of disease among 838 swimmers in 2010 was 42% compared to 8% among 931 swimmers in the 2011 competition (relative risk (RR) 5.0; 95% CI: 4.0-6.39). In 2010, illness was associated with having unintentionally swallowed contaminated water (RR 2.5; 95% CI: 1.8-3.4); and the risk increased with the number of mouthfuls of water swallowed. Confirmed aetiologies of infection included Campylobacter, Giardia lamblia and diarrhoeagenic E. coli. The study demonstrated a considerable risk of illness from water intake when swimming in contaminated seawater in 2010, and a small but measureable risk from non-polluted water in 2011. This suggests a significant risk of disease in people ingesting small amounts of flood water following extreme rainfall in urban areas.

A long-lasting outbreak of Salmonella Typhimurium U323 associated with several pork products, Denmark, 2010

This paper shows that control of foodborne disease outbreaks may be challenging even after establishing the source of infection. An outbreak of Salmonella Typhimurium U323 infections occurred in Denmark from March to September 2010, involving 172 cases. Before the detection of human cases, several positive isolates of the outbreak strain had been found in a particular pig slaughterhouse and thus early traceback, investigation and control measures were possible. Several batches of pork and pork products were recalled and the slaughterhouse was closed twice for disinfection. No single common food item was identified as the outbreak source, but repeated isolation of the outbreak strain from the slaughterhouse environment and in pork and products as well as patient interviews strongly suggested different pork products as the source of infection. Furthermore, a matched case-control study identified a specific ready-to-eat spreadable pork sausage (teewurst) as the source of a sub-outbreak (matched odds ratio 17, 95% confidence interval 2·1-130).

Detection of antibodies to Campylobacter in humans using enzyme-linked immunosorbent assays: a review of the literature

Campylobacteriosis is the most common cause of bacterial foodborne illness in the European Union and the United States. Infection with Campylobacter spp. is frequently associated with different sequelae including neuropathies and reactive arthritis. Diagnosis is mainly by bacterial culturing which is time consuming, expensive, and not well suited for diagnosing sequelae or identifying infections from stool samples with nonviable bacteria. Serologic assays, in particular ELISAs, are well suited for this purpose, but, at present, there is no international consensus on antibody assays for human campylobacteriosis. In an extensive literature review, 19 studies validating such assays were identified of which 13 were more than 10 years old. We conclude that the best validated of these assays are developed and used in-house for research purposes rather than for routine diagnostics. Considering the burden of disease and potential long-term severity of Campylobacter infections, developing a standardized, commercially available antibody assay could be of great benefit for diagnostic and surveillance purposes worldwide.

Salmonella Typhimurium outbreak associated with smoked pork tenderloin in Denmark, January to March 2011

Abstract Background: An outbreak of salmonellosis (Salmonella Typhimurium, phage type DT120) occurred from 26 January to 15 March 2011, in Denmark, with 22 laboratory confirmed cases. Hypothesis-generating patient interviews gave rise to the suspicion that smoked pork tenderloin was the source of infection. The primary objective of this study was to identify the source of the outbreak in order to initiate appropriate control measures. Methods: A matched (1:2) case–control study was conducted. A case was defined as a person residing in Denmark whose stool sample tested positive for S. Typhimurium, with a particular multilocus variable-number tandem repeat profile, from January to March 2011. Controls were matched to cases on age, gender, and municipality of residence. Results: Of 21 interviewed cases, 19 (91%) indicated that they typically ate smoked pork tenderloin more than once a week, compared with 13 (33%) of 39 interviewed controls (matched odds ratio 19.6, 95% confidence interval 2.6–153). Eighteen (86%) cases indicated that they might have consumed smoked pork tenderloin the week before becoming ill, compared with 1 (4%) control who had eaten the product a week before the interview. Two cases provided the brand name of the product and the supermarket where it was purchased. Conclusions: The results show a strong statistically significant association between the consumption of smoked pork tenderloin and S. Typhimurium infection. The European Rapid Alert System for Food and Feed was used to notify these findings to the competent authorities in the country of origin of the product. Subsequently, the smoked pork tenderloin of the brand in question, dating from 1 January to 1 May 2011, was recalled from consumers.

The association between demographic factors and increased antibiotic consumption in Denmark 2001 to 2010

Abstract From 2001 to 2010, the consumption of antibiotics in Denmark increased by 32%. The objective of this study was to investigate the potential demographic factors associated with this increase. Defined daily doses (DDD) per 1000 inhabitant-days for the leading antibiotic groups and substances in primary health care in 2001 and 2010 were adjusted for population size and compared between and within age groups and genders. An increased antibiotic consumption was observed for all age groups between 2001 and 2010. Particular age-specific increases in the consumption of tetracyclines, extended-spectrum penicillins, and amoxicillin/clavulanic acid were observed. The generally increased consumption of antibacterial agents in the Danish population during the past decade was driven by people older than 65 y and, to a lesser extent, those aged 20–39 y. Evidence suggests that this increase may reflect general practitioners prescribing more antibiotics per visit and in larger doses.

Epidemiology of campylobacteriosis in Denmark 2000–2015

Campylobacter is the most frequently occurring cause of bacterial gastroenteritis in Europe. Unlike other zoonotic diseases, European‐wide incidences of Campylobacter infections have increased during the past decade, resulting in a significant disease burden. In Denmark, campylobacteriosis is notifiable by laboratory and a unique registration system of electronic transfer and storage of notified Campylobacter cases linked to the national person register of age, gender and geographical location allows collection of comprehensive case data. Using national surveillance data, we describe Campylobacter infections in Denmark from 2000 to 2015, focusing on age‐specific incidences, geography, seasonality and outbreaks. During the observed period, a total of 60,725 Campylobacter infections were registered with a mean annual incidence of 69.3 cases/100,000 population. From 2000 to 2014, the incidence of campylobacteriosis decreased by 20%, followed by an apparent increase of 20% from 2014 to 2015. Approximately one‐third of cases were travel‐related. Incidences were highest in males, young adults aged 20–29 years and children under 5 years of age. Generally, children under 10 years of age living in rural areas were at higher risk of infection. Infection patterns were seasonal with an increase from May to October, peaking in August. Outbreaks were identified each year, including four large waterborne outbreaks which all occurred following heavy rainfall events. For the most part, patterns of Campylobacter infection in Denmark during 2000 to 2015 remained remarkably constant and followed what is known about the disease with respect to demographic, temporal and spatial characteristics. To establish better targeted prevention and control measures, the current knowledge gaps regarding both Campylobacter microbiology (degree of clonal diversity and clustering) and the importance of different risk factors (food versus environment/climate) need to be filled.

Fecal carriage of extended-spectrum and AmpC β-lactamase-producing Enterobacteriaceae in surgical patients before and after antibiotic prophylaxis

The impact of antibiotic prophylaxis on fecal carriage of ESBL-/AmpC-/carbapenemase-producing Enterobacteriaceae (CPE) was investigated. Patients admitted for elective surgery or diagnostic procedure in a Department of Surgical Gastroenterology (SG) (n= 450) and Orthopedic Surgery (OS) (n= 300) provided a fecal swab at admission and responded to a questionnaire on possible exposures. SG patients received gentamicin/penicillin G (±metronidazole); OS patients received cefuroxime. Two days after surgery a second swab was taken. From SG patients, 6% of first swabs and 9% of second swabs were positive for ESBL-/AmpC-producers. A similar carriage rate was observed in OS patients (6% and 8%, respectively). No CPE were detected. Escherichia coli was the predominant species and blaCTX-M-15 (29% and 22%) and blaCTX-M-14 (11% and 17%) were the most prevalent ESBL genotypes among SG and OS patients. Two different prophylactic antibiotic regimens had no impact on carriage rates. Previous hospitalization and antimicrobial treatment were associated with carriage for SG patients.

Detecting Non-typhoid Salmonella in Humans by Enzyme-Linked Immunosorbent Assays (ELISAs): Practical and Epidemiological Aspects

Salmonellosis caused by non-typhoid Salmonella serotypes is one of the most common causes of food-borne illness throughout the world. The diagnosis is primarily by culture and more recently molecular methods, whereas the use of serological methods for diagnosis of Salmonella infections is limited by high running costs as well as low sensitivity and specificity. Fast and reliable immunoassays for detection of S. typhi subunit antigens are commercially available, but there is no international consensus of similar tests for non-typhoid salmonellosis. Most immunoassays for non-typhoid human Salmonella diagnosis are developed in-house and used in-house for research or regional surveillance purposes. Only few laboratories use serology for the diagnosis of Salmonella-associated complications such as arthritis. Considering the current burden of disease, the development of a validated and standardized, commercially available antibody assay for diagnosing non-typhoid human salmonellosis can be of great benefit for diagnostic and surveillance purposes throughout the world.