Implementation of a broad public health approach to COVID-19 in Sweden, January 2020 to May 2022.

In 2020, the world had to adapt to a pandemic caused by a then novel coronavirus. In addition to its direct impact on morbidity and mortality, the COVID-19 pandemic brought unprecedented control measures and challenges to both individuals and society. Sweden has been seen by many as an outlier in the management of the pandemic. It is therefore of special interest to document the actual management of the pandemic in Sweden during its first 2 years and how public health was affected. In the authors opinion, within the Swedish context, it has been possible to achieve a similar level of effect on mortality and morbidity through recommendations as was achieved through stringent legal measures in comparable countries. This is supported by comparisons of excess mortality that have been published. Furthermore, we see in the available data that the consequences on mental health and living habits were very limited for the majority of the population. Trust in public institutions is high in Sweden, which has been important and is part of the context that made it possible to manage a pandemic with relatively 'soft' measures. We acknowledge challenges in protecting certain vulnerable groups, particularly during the first and second wave.

Revisiting colistin susceptibility testing: will adding calcium to Mueller-Hinton agar improve the detection of colistin resistance?

OBJECTIVE: The aim was to investigate whether adding calcium to Mueller-Hinton agar for gradient MIC or disc diffusion tests could improve separation between colistin-susceptible and -resistant populations of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp. and if this method could provide a reliable screening test for colistin resistance in routine laboratories. METHODS: An isolate collection of 57 E. coli, K. pneumoniae, P. aeruginosa and Acinetobacter spp. was tested. Ca2+ in concentrations from 2.5 to 40 mM was added to the Mueller-Hinton agar plates used for gradient MIC and disc diffusion tests. Broth microdilution (ISO 20776-1) MIC determination was used as reference. Escherichia coli and K. pneumoniae were investigated for colistin resistance genes. RESULTS: Results were similar for gradient tests and disc diffusion for all species. Correlation between phenotypic expression of resistance and resistance genes was not absolute. Addition of Ca2+ to Mueller-Hinton agar improved separation between colistin-susceptible and -resistant isolates for E. coli. For K. pneumoniae, separation was improved for isolates with mcr genes, but not for isolates harbouring other colistin resistance mechanisms. To further increase the concentrations of Ca2+ did not improve the separation between susceptible and resistant isolates of E. coli and K. pneumoniae. For P. aeruginosa and Acinetobacter species, addition of Ca2+ did not improve separation between susceptible and resistant populations. DISCUSSION: The results from this study show that addition of Ca2+ to the Mueller-Hinton agar does not sufficiently improve detection of colistin resistance by gradient MIC or disc diffusion tests for use in a routine laboratory.

Worsening epidemiological situation of carbapenemase-producing Enterobacteriaceae in Europe, assessment by national experts from 37 countries, July 2018.

A survey on the epidemiological situation, surveillance and containment activities for carbapenemase-producing Enterobacteriaceae (CPE) was conducted in European countries in 2018. All 37 participating countries reported CPE cases. Since 2015, the epidemiological stage of CPE expansion has increased in 11 countries. Reference laboratory capability, dedicated surveillance and a specific national containment plan are in existence in 33, 27 and 14 countries, respectively. Enhanced control efforts are needed for CPE containment in Europe.

ESBL-producing Escherichia coli in Swedish gulls-A case of environmental pollution from humans?

ESBL-producing bacteria are present in wildlife and the environment might serve as a resistance reservoir. Wild gulls have been described as frequent carriers of ESBL-producing E. coli strains with genotypic characteristics similar to strains found in humans. Therefore, potential dissemination of antibiotic resistance genes and bacteria between the human population and wildlife need to be further investigated. Occurrence and characterization of ESBL-producing E. coli in Swedish wild gulls were assessed and compared to isolates from humans, livestock and surface water collected in the same country and similar time-period. Occurrence of ESBL-producing E. coli in Swedish gulls is about three times higher in gulls compared to Swedish community carriers (17% versus 5%) and the genetic characteristics of the ESBL-producing E. coli population in Swedish wild gulls and Swedish human are similar. ESBL-plasmids IncF- and IncI1-type carrying ESBL-genes blaCTX-M-15 or blaCTX-M-14 were most common in isolates from both gulls and humans, but there was limited evidence of clonal transmission. Isolates from Swedish surface water harbored similar genetic characteristics, which highlights surface waters as potential dissemination routes between wildlife and the human population. Even in a low-prevalence country such as Sweden, the occurrence of ESBL producing E. coli in wild gulls and the human population appears to be connected and the occurrence of ESBL-producing E. coli in Swedish gulls is likely a case of environmental pollution.

Community carriage of ESBL-producing Escherichia coli is associated with strains of low pathogenicity: a Swedish nationwide study.

OBJECTIVES: Community carriage of ESBL-producing Escherichia coli (EPE) is common worldwide and there is a need to understand the connection between carriage and infection. We compared the molecular characteristics of EPE among Swedish community carriers with those of EPE causing invasive infections. METHODS: We collected 2134 faecal samples from randomly selected Swedish inhabitants and examined them for the presence of EPE. All participating volunteers answered a questionnaire about putative risk factors for EPE carriage. Suspected EPE isolates (n = 418) from patients with bloodstream infection (BSI) were collected from Swedish laboratories. Isolates were genotypically and phenotypically characterized. RESULTS: Our results show that the EPE population found in carriers generally had lower pathogenicity compared with the isolates from BSIs, since carriers had a lower proportion of E. coli belonging to phylogroup B2, ST131 and ST131 subclone H30-Rx. Isolates from carriers also had lower levels of multiresistance. The Swedish carriage rate of EPE was 4.7% (101/2134) among healthy volunteers. Risk factors associated with carriage were travel to countries in Asia (OR = 3.6, 95% CI = 1.4-9.2) and Africa (OR = 3.6, 95% CI = 1.7-7.7) and a diet without pork (OR = 0.5, 95% CI = 0.3-0.8 for pork eaters). CONCLUSIONS: E. coli host factors previously associated with higher pathogenicity were all more common in BSIs compared with carriers. This indicates that the risk of invasive infection with EPE may be relatively modest in many community carriers and that EPE carriage of high-risk strains should be the focus of attention for prevention.

Limited Dissemination of Extended-Spectrum ß-Lactamase- and Plasmid-Encoded AmpC-Producing Escherichia coli from Food and Farm Animals, Sweden.

Extended-spectrum ß-lactamase (ESBL)- and plasmid-encoded ampC (pAmpC)-producing Enterobacteriaceae might spread from farm animals to humans through food. However, most studies have been limited in number of isolates tested and areas studied. We examined genetic relatedness of 716 isolates from 4,854 samples collected from humans, farm animals, and foods in Sweden to determine whether foods and farm animals might act as reservoirs and dissemination routes for ESBL/pAmpC-producing Escherichia coli. Results showed that clonal spread to humans appears unlikely. However, we found limited dissemination of genes encoding ESBL/pAmpC and plasmids carrying these genes from foods and farm animals to healthy humans and patients. Poultry and chicken meat might be a reservoir and dissemination route to humans. Although we found no evidence of clonal spread of ESBL/pAmpC-producing E. coli from farm animals or foods to humans, ESBL/pAmpC-producing E. coli with identical genes and plasmids were present in farm animals, foods, and humans.

Legionella norrlandica sp. nov., isolated from the biopurification systems of wood processing plants.

Fourteen isolates of an unknown species identified as belonging to the genus Legionella by selective growth on BCYE agar were isolated from the biopurification systems of three different wood processing plants. The mip gene sequence of all 14 isolates was identical and a close match alignment revealed 86 % sequence similarity with Legionella pneumophila serogroup 8. The whole genome of isolate LEGN(T) was sequenced, and a phylogenetic tree based on the alignment of 16S rRNA, mip, rpoB, rnpB and the 23S-5S intergenic region clustered LEGN(T) with L. pneumophila ATCC 33152(T). Analysis of virulence factors showed that strain LEGN(T) carries the majority of known L. pneumophila virulence factors. An amoeba infection assay performed to assess the pathogenicity of strain LEGN(T) towards Acanthamoeba castellanii showed that it can establish a replication vacuole in A. castellanii but does not significantly affect replication of amoebae. Taken together, the results confirm that strain LEGN(T) represents a novel species of the genus Legionella, for which the name Legionella norrlandica sp. nov. is proposed. The type strain is LEGN(T) ( = ATCC BAA-2678(T) = CCUG 65936(T)).

Surveillance of antimicrobial resistance among Escherichia coli in wastewater in Stockholm during 1 year: does it reflect the resistance trends in the society?

The resistance patterns of Escherichia coli in untreated (raw) urban wastewater (UW) was monitored by repeated sampling during 1 year. Comparison with data from wastewater samples collected from hospital wastewater (HW) in the same urban area was made. A total of 1326 E. coli isolates from 17 UW samples and 451 isolates from six HW samples were analysed by typing using the PhenePlate™ system, and their susceptibility towards 10 antibiotics was determined. Resistance to at least one antibiotic was observed in 34% of the UW isolates and 55% of the HW isolates. For UW isolates, phenotypic diversity was lower among antibiotic-susceptible than among antibiotic-resistant isolates, indicating a higher presence of clonal groups among susceptible isolates. Total antibiotic resistance measured as the Multiple Antibiotic Resistance (MAR) index was 0.08 for UW compared with 0.19 for HW, and increased over time for UW isolates, indicating increasing resistance among E. coli in the urban population during the studied time period. Resistance to all included ß-lactam antibiotics was detected in 2.4% of UW isolates and 14.0% of HW isolates, and 73/75 (97%) analysed isolates were confirmed to be extended-spectrum ß-lactamase (including plasmid-mediated AmpC)-producing E. coli. Thus, by cultivating samples from wastewater and analysing many independent isolates per sample, increasing frequencies of antibiotic resistance in UW were detected during 1 year that may reflect increasing faecal carriage of resistant bacteria in the society. Surveillance of antibiotic resistance in wastewater could be a valuable tool for screening of resistance trends on a population level.

Escherichia coli with extended-spectrum beta-lactamases or transferable AmpC beta-lactamases and Salmonella on meat imported into Sweden.

The presence of Enterobacteriaceae producing extended spectrum beta-lactamases (ESBL) or transferable AmpC beta-lactamases (pAmpC) is increasingly being reported in humans and animals world-wide. Their occurrence in food-producing animals suggests that meat is a possible link between the two populations. This study investigated the occurrence and characteristics of Salmonella and ESBL- or pAmpC-producing E. coli in 430 samples of beef, pork and broiler meat imported into Sweden, in order to provide data required for assessing the potential public health risk of these bacteria in food. Depending on region of origin, ESBL/pAmpC-producing E. coli were found in 0-8% of beef samples, 2-13% of pork samples and 15-95% of broiler meat samples. The highest prevalence was in South American broiler meat (95%), followed by broiler meat from Europe (excluding Denmark) (61%) and from Denmark (15%). Isolates from meat outside Scandinavia were generally defined as multiresistant. A majority of the ESBL/pAmpC genes were transferable by conjugation. Bla(CTX-M-2) and bla(CTX-M-8) were the dominant genes in E. coli from South American broiler meat, whereas bla(CMY-2) and bla(CTX-M-1) dominated in European meat. The majority of bla(CMY-2) and bla(CTX-M-1) were situated on plasmids of replicon type incK and incI1, respectively. The same combinations of ESBL/pAmpC genes and plasmids have been described previously in clinical human isolates. Salmonella was found in five samples tested, from European pork and broiler meat. No Salmonella isolate was resistant to third-generation cephalosporins. In conclusion, meat imported into Sweden, broiler meat in particular, is a potential source of human exposure to ESBL- and pAmpC-producing E. coli.