Low Level Of Antimicrobial Resistance Research Articles

Antibiotic Guideline Adherence at the Emergency Department: A Descriptive Study from a Country with a Restrictive Antibiotic Policy.

Denmark has a low level of antimicrobial resistance (AMR). Patients hospitalized with suspected infection often present with unspecific symptoms. This challenges the physician between using narrow-spectrum antibiotics in accordance with guidelines or broad-spectrum antibiotics to compensate for diagnostic uncertainty. The aim of this study was to investigate adherence to a restrictive antibiotic guideline for the most common infection in emergency departments (EDs), namely community-acquired pneumonia (CAP). This multicenter descriptive cross-sectional study included adults admitted to Danish EDs with a suspected infection. Data were collected prospectively from medical records. We included 954 patients in the analysis. The most prescribed antibiotics were penicillin with beta-lactamase inhibitor at 4 h (307 (32.2%)), 48 h (289 (30.3%)), and day 5 after admission (218 (22.9%)). The empirical antibiotic treatment guidelines for CAP were followed for 126 (31.3%) of the CAP patients. At 4 h, antibiotics were administered intravenously to 244 (60.7%) of the CAP patients. At day 5, 218 (54.4%) received oral antibiotics. Adherence to CAP guidelines was poor. In a country with a restrictive antibiotic policy, infections are commonly treated with broad-spectrum antibiotics against recommendations.

Staphylococcus aureus Carriage in the Nasotracheal Cavities of White Stork Nestlings (Ciconia ciconia) in Spain: Genetic Diversity, Resistomes and Virulence Factors.

The molecular ecology of Staphylococcus aureus in migratory birds (such as white storks) is necessary to understand their relevance in the "One Health" ecosystems. This study determined the nasotracheal carriage rates of S. aureus from white storks in Southern Spain and genetically characterized the within-host diversity. A collection of 67 S. aureus strains, previously obtained from 87 white stork nestlings (52 nasal and 85 tracheal samples) fed by their parents with food foraged in natural and landfill habitats, were tested for their antimicrobial resistance (AMR) phenotypes. Moreover, the AMR genotypes, immune evasion cluster (IEC), virulence genes and the detection of CC398 lineage were studied by PCR. The spa types and multilocus-sequencing-typing (MLST) were also determined by PCR and sequencing. Staphylococcus aureus carriage was found in 31% of storks (36.5%/11.9% in nasal/tracheal samples). All isolates were methicillin-susceptible (MSSA) and 8.8% of them were also susceptible to all tested antibiotics. The AMR phenotype/percentage/genes detected were as follows: penicillin/79.1%/blaZ; erythromycin-clindamycin-inducible/19.1%/ermA, ermT; tetracycline/11.9%/tetK; clindamycin/4.5%/lnuA and ciprofloxacin/4.5%. Twenty-one different spa types, including 2 new ones (t7778-ST15-CC15 and t18009-ST26-CC25), were detected and ascribed to 11 clonal complexes (CCs). MSSA-CC398 (8.2%), MSSA-CC15 (7.1%) and MSSA-ST291 (5.9%) were the most prevalent lineages in storks. Moreover, tst-positive (MSSA-CC22-t223 and MSSA-CC30-t1654), eta-positive (MSSA-CC9-t209) and etb-positive strains (MSSA-CC45-t015) were detected in four storks. The 18.5% of storks harboured distinct MSSA strains (with different lineages and/or AMR genes). Nestlings of storks foraging in landfills (10 CCs) had more diverse S. aureus strains than those of parents foraging in natural habitats (3 CCs). Low level of AMR was demonstrated among S. aureus strains. The predominance of MSSA-CC398 (an emergent clade) and toxigenic MSSA strains in stork nestlings highlight the need for continuous surveillance of S. aureus in wild birds.

Antibiotic Resistance and Plasmid Profile Analysis of Salmonella Enteritidis Isolated in Siberia and the Far East of Russia between 1990 and 2017.

Salmonella is one of the major causes of foodborne disease outbreaks globally. Specifically, Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) is one of the major causes of zoonotic Salmonella infection in humans worldwide. In this study, we present data on antimicrobial resistance (AMR) and plasmid profiles of S. Enteritidis strains isolated from patients, food, and the environment in Siberia and the Far East of Russia obtained during Salmonella monitoring between 1990 and 2017. A total of 345 S. Enteritidis isolates were tested by the disk diffusion method with a set of 15 antibiotics using EUCAST breakpoints v. 10 and by plasmid profile analysis using the alkaline lysis method. The results have shown a substantial decrease in susceptibility to aminoglycosides and quinolones during the study period. No significant differences were found in the susceptibility of strains between regions as well as in the its correlation with different plasmid types of the pathogen. Several S. Enteritidis strains were found to be resistant to ampicillin, kanamycin, tetracycline, chloramphenicol, and cephalosporins. All tested S. Enteritidis strains were susceptible only to imipenem. In this study, we observed a relatively low level of AMR in S. Enteritidis strains isolated in Siberia and the Far East of Russia. Nevertheless, it is important to continue the molecular genetic monitoring and AMR surveillance of S. Enteritidis to track further increases in AMR using conventional phenotypic susceptibility testing and by introducing whole-genome sequencing to identify AMR mechanisms.

Food Service Pork Chops from Three U.S. Regions Harbor Similar Levels of Antimicrobial Resistance Regardless of Antibiotic Use Claims

Pork products from animals "raised without antibiotics" (RWA) are assumed to harbor lower levels of antimicrobial resistance (AMR) than conventional (CONV) pork products with no claims regarding use of antimicrobial agents during production. A total of 372 pork chop samples from CONV (n = 190) and RWA (n = 182) production systems were collected over 13 months from three food service suppliers. The following bacteria were cultured: Escherichia coli, tetracycline-resistant (TETr) E. coli, third-generation cephalosporin-resistant (3GCr) E. coli, Salmonella enterica, TETr Salmonella, 3GCr Salmonella, nalidixic acid-resistant Salmonella, Enterococcus spp., TETr Enterococcus, erythromycin-resistant Enterococcus, Staphylococcus aureus, and methicillin-resistant S. aureus. Production system did not significantly impact the detection of cultured bacteria (P > 0.05). Metagenomic DNA was isolated from each sample, and equal amounts of metagenomic DNA were pooled by supplier, month, and production system for 75 pooled samples (38 CONV, 37 RWA). Quantitative PCR was used to assess the abundances of the following 10 AMR genes: aac(6')-Ie-aph(2″)-Ia, aadA1, blaCMY-2, blaCTX-M, blaKPC-2, erm(B), mecA, tet(A), tet(B), and tet(M). For all 10 AMR genes, abundances did not differ significantly (P > 0.05) between production systems. These results suggest that use of antimicrobial agents during swine production minimally impacts the AMR of bacteria in pork chops.

High occurrence of enterotoxigenic isolates and low antibiotic resistance rates of Staphylococcus aureus isolated from raw milk from cows and ewes.

This study aimed to analyse the frequency of genes encoding virulence factors and to characterize resistance profiles of Staphylococcus aureus isolated from raw milk. In total, 47 and 9 S.aureus isolates were recovered from 150 and 100 raw bovine and ovine milk samples, respectively, in Tunisia. The majority of isolates was resistant to penicillin, and no methicillin-resistant S.aureus was detected. Eighteen and two isolates harboured etd and eta genes respectively. Sixteen enterotoxin-encoding genes were detected (n, %): sed (25, 44·6%), sec (16, 28·6%), sei (16, 28·6%), seh (13, 23·2%), seln (13, 23·2%), sell (10, 17·8%), seg (9, 16%), selu (8, 14·3%), selq (7, 12·5%), selo (7, 12·5%), selm (7, 12·5%), seb (7, 12·5%), sea (6, 10·7%), selk (3, 5·4%), ser (1, 1·8%) and selp (1, 1·8%). Ten isolates carried the tsst1 gene. All isolates carried the haemolysin toxin (hla, hld and hlg). The immune evasion cluster system-type B was predominant (20 isolates) followed by C (3 isolates), A and E (1 isolate each). The occurrence of enterotoxigenic S.aureus in raw milk constitutes a potential risk for human health. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper describes the characteristics of Staphylococcus aureus isolated from raw milk samples from healthy cows and ewes collected from small family farms in Tunisia. Fifty-six strains were analysed by determining their antibiotic susceptibility and genes encoding antibiotic resistance and virulence factors. Methicillin-resistant strains were not detected, and overall low level of antimicrobial resistance was reported. However, our strains harboured several genes encoding virulence factors and 87·5% of them carried at least one gene encoding for enterotoxins showing a high risk of spread of food-borne diseases.

Global survey maps antimicrobial resistance

Infectious-disease surveillance programs designed to track antimicrobial resistance face practical, ethical, and legal difficulties. Patient data must be anonymized, and it can be difficult to compare data collected from different countries and hospitals. The answer to these challenges, an international team believes, is sewage (Nat. Commun. 2019, DOI: 10.1038/s41467-019-08853-3). Led by Frank Aarestrup at the Technical University of Denmark, researchers recruited people at 79 sites in 60 countries to the Global Sewage Surveillance Project. Those volunteers collected sewage samples and sent them to Denmark, where researchers looked for genes coding for antimicrobial resistance. They found global and regional differences in antimicrobial-resistance gene diversity and abundance. Microbes in samples from Australia, New Zealand, North America, and western Europe generally had lower levels of antimicrobial resistance; those from Asia, Africa, and South America generally had higher levels. The study found that sanitary conditions and the general health of the population were most

Serotyping and antimicrobial resistance of Mannheimia haemolytica strains from European cattle with bovine respiratory disease

The objective of this study was to assess the prevalence of three serotypes, A1, A2, and A6 in 98 M. haemolytica isolates collected from clinical BRD cases in European cattle and assess their antimicrobial resistance profiles. Isolates were characterized by serotyping (plate agglutination and serotype specific PCR) and antimicrobial susceptibility testing. The study identified a predominance of serotypes A1 (59%) and A6 (22%) in European M. haemolytica isolates exhibiting a relatively low level of antimicrobial resistance. A comprehensive understanding of the relative prevalence of different M. haemolytica serotypes in Europe informs a targeted approach for vaccine design against BRD.

Clonal diversity and geographic distribution of methicillin-resistant Staphylococcus pseudintermedius from Australian animals: Discovery of novel sequence types

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an increasingly prevalent pathogen in veterinary medicine. This study examined the molecular epidemiology of clinical MRSP isolated from Australian animals. Clinical staphylococci submitted to all Australian veterinary diagnostic laboratories were collected during 2013 and identified using traditional phenotypic tests and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Phenotypic antimicrobial resistance was determined using broth microdilution and disk diffusion. MRSP isolates were characterized by whole genome sequencing which included identification of the mecA gene. Phylogenetic relationships were inferred by comparison of single nucleotide polymorphisms. Of the 669 S. pseudintermedius isolates collected from dogs, cats and cattle, 77 (11.5%) were MRSP. Nineteen multilocus sequence types (STs) were identified, with most isolates belonging to one of five STs (ST71, ST497, ST316, ST496 and ST45). Phylogenetic analysis revealed that Australian ST71 appears closely related to ST71 from overseas. ST497 and ST496 represented novel sequence types, not previously reported outside Australia. Most other STs were novel and only distantly related to each other. Geographical clustering of STs was observed. All isolates belonging to the five main STs were multi- to extensively- drug resistant while isolates from singleton STs generally had lower levels of antimicrobial resistance. The frequency of ciprofloxacin, trimethoprim-sulfamethoxazole, gentamicin, chloramphenicol and tetracycline resistance varied significantly between STs (p<0.01). Australian MRSP isolates are phylogenetically diverse, with a mix of previously unreported and well known international MRSP clones that demonstrate geographic clustering and exhibit both multidrug-resistant and extensively drug-resistant phenotypes.

Antimicrobial resistance status of Enterococcus from Australian cattle populations at slaughter.

Antimicrobial agents are used in cattle production systems for the prevention and control of bacterial associated diseases. A consequence of their use is the potential development of antimicrobial resistance (AMR). Enterococcus faecium and Enterococcus faecalis that are resistant to antimicrobials are of increased concern to public health officials throughout the world as they may compromise the ability of various treatment regimens to control disease and infection in human medicine. Australia is a major exporter of beef; however it does not have an ongoing surveillance system for AMR in cattle or foods derived from these animals. This study examined 910 beef cattle, 290 dairy cattle and 300 veal calf faecal samples collected at slaughter for the presence of enterococci. Enterococcus were isolated from 805 (88.5%) beef cattle faeces, 244 (84.1%) dairy cattle faeces and 247 (82.3%) veal calf faeces with a total of 800 enterococci subsequently selected for AMR testing. The results of AMR testing identified high levels of resistance to antimicrobials that are not critically or highly important to human medicine with resistance to flavomycin (80.2%) and lincomycin (85.4–94.2%) routinely observed. Conversely, resistance to antibiotics considered critically or highly important to human medicine such as tigecycline, daptomycin, vancomycin and linezolid was not present in this study. There is minimal evidence that Australian cattle production practices are responsible for disproportionate contributions to AMR development and in general resistance to antimicrobials of critical and high importance in human medicine was low regardless of the isolate source. The low level of antimicrobial resistance in Enterococcus from Australian cattle is likely to result from comprehensive controls around the use of antimicrobials in food-production animals in Australia. Nevertheless, continued monitoring of the effects of all antimicrobial use is required to support Australia’s reputation as a supplier of safe and healthy food.

Genomic relatedness of Staphylococcus pettenkoferi isolates of different origins.

PurposeThe aim of the study was to characterize clinical and environmental Staphylococcus pettenkoferi isolates with regard to genomic diversity and antibiotic susceptibility pattern. Repetitive-sequence-based PCR and core genome phylogenetic analysis of whole-genome sequencing (WGS) data verified the presence of distinct clades comprising closely related S. pettenkoferi isolates from different geographical locations and origins.MethodologyPhylogenetic relationships between 25 S. pettenkoferi isolates collected from blood cultures and intra-operative air sampling were determined by repetitive-sequence-based PCR typing and analysis of ~157 000 SNPs identified in the core genome after WGS. Antibiotic susceptibility testing and tests for biofilm production (microtitre plate assay) were performed.ResultsRepetitive-sequence-based PCR as well as WGS data demonstrated the close relatedness of clinically significant blood culture isolates to probable contaminants, as well as to environmental isolates. Antibiotic-susceptibility testing demonstrated a low level of antimicrobial resistance. The mecA gene was present in two cefoxitin-resistant isolates. No isolates were found to produce biofilm.ConclusionClose genomic relatedness of S. pettenkoferi isolates from different geographical locations and origins were found within clades, but with substantial genomic difference between the two major clades. The ecological niche of S. pettenkoferi remains unconfirmed, but the presence of S. pettenkoferi in the air of the operating field favours the suggestion of a role in skin flora. Identification of S. pettenkoferi in clinical samples should, in a majority of cases, most likely be regarded as a probable contamination, and its role as a possible pathogen in immunocompromised hosts remains to be clarified.

Antimicrobial resistance remains a threat

Antibiotic-resistant bacteria are still showing up at alarming rates in people, farm animals, and food in the European Union, a report by the European Food Safety Authority (EFSA) and the European Centre for Disease Prevention & Control concludes. Just as in previous years, the agencies report regional differences in antimicrobial resistance levels, with the lowest levels in northern and western Europe. “These geographic variations are most likely related to differences in antimicrobial use across the EU,” says Marta Hugas, head of EFSA’s Biological Hazards & Contaminants unit. “For example, countries where actions have been taken to reduce, replace, and rethink the use of antimicrobials in animals show lower levels of antimicrobial resistance and decreasing trends.” For the first time, the agencies detected bacteria resistant to carbapenem antibiotics in pigs and meat from pigs. Such drugs are often used as a last resort in treating multi-drug-resistant infections in people. The agencies

Genetic characterization and antimicrobial resistance of Staphylococcus aureus isolated from bovine milk in Tunisia.

This paper describes the characteristics ofStaphylococcus aureus isolated from bulk tank and individual cow milk in Tunisia. All strains were genotyped by spa typing and RS-PCR, a method based on the amplification of the 16S-23S rRNA intergenic spacer region, and multiplex PCRs for 22 virulence genes. A selected subsample of strains was also genotyped by multilocus sequence typing. All strains were tested for antimicrobial resistance. Our study evidences a predominance of strains belonging to Clonal Complex 97. Methicillin-resistant strains were not detected, and overall low level of antimicrobial resistance was reported.

An audit and feedback intervention study increased adherence to antibiotic prescribing guidelines at a Norwegian hospital.

BackgroundAppropriate antibiotic prescribing is associated with favourable levels of antimicrobial resistance (AMR) and clinical outcomes. Most intervention studies on antibiotic prescribing originate from settings with high level of AMR. In a Norwegian hospital setting with low level of AMR, the literature on interventions for promoting guideline-recommended antibiotic prescribing in hospital is scarce and requested. Preliminary studies have shown improvement potentials regarding antibiotic prescribing according to guidelines. We aimed to promote appropriate antibiotic prescribing in patients with community-acquired pneumonia (CAP) and acute exacerbations of chronic obstructive pulmonary disease (AECOPD) at a respiratory medicine department in a Norwegian University hospital. Our specific objectives were to increase prescribing of appropriate empirical antibiotics, reduce high-dose benzylpenicillin and reduce total treatment duration.MethodsWe performed an audit and feedback intervention study, combined with distribution of a recently published pocket version of the national clinical practice guideline. We included patients discharged with CAP or AECOPD and prescribed antibiotics during hospital stay, and excluded those presenting with aspiration, nosocomial infection and co-infections. The pre- and post-intervention period was 9 and 6 months, respectively. Feedback was provided orally to the department physicians at an internal-educational meeting. To explore the effect of the intervention on appropriate empirical antibiotics and mean total treatment duration we applied before-after analysis (Student’s t-test) and interrupted time series (ITS). We used Pearson’s χ2 to compare dose changes.ResultsIn the pre-and post-intervention period we included 253 and 155 patients, respectively. Following the intervention, overall mean prescribing of appropriate empirical antibiotics increased from 61.7 to 83.8 % (P < 0.001), overall mean total treatment duration decreased from 11.2 to 10.4 days (P = 0.015), and prescribing of high-dose benzylpenicillin decreased from 48.8 to 38.6 % (P = 0.125). With ITS we found that six months post-intervention, the effect on appropriate empirical antibiotic prescribing had increased and sustained, while the effect on treatment duration was at pre-intervention level.ConclusionThe combination of audit and feedback plus distribution of a pocket version of guideline recommendations led to a substantial increase in prescribing of appropriate empirical antibiotics, which is important due to favourable effect on AMR and clinical outcomes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1426-1) contains supplementary material, which is available to authorized users.

Low‐level resistance and clonal diversity of Pseudomonas aeruginosa among chronically colonized cystic fibrosis patients

A prospective study was conducted in Brazil to evaluate antimicrobial resistance patterns and molecular epidemiology of Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients with chronic lung infection. All isolates were obtained between May 2009 and June 2010 from 75 patients seen in four reference centers in Brazil: HCPA (20 patients) and HEOM (15 patients), located in southern and northeastern Brazil, respectively; IFF (20 patients) and HUPE (20 patients), both in southwestern Brazil. Antimicrobial susceptibility testing, PCR for detection of carpapenemases, and pulsed-field gel electrophoresis (PFGE) were performed in 274 isolates. A total of 224 PFGE types were identified and no clones were found circulating among the centers or within the same center. Despite the chronic infection, most patients were colonized by intermittent clones. Only three patients (4%) maintained the same clone during the study. The resistance rates were lower than 30% for the majority of antimicrobials tested in all centers and only 17% of isolates were multiresistant. Isolates (n = 54) with reduced susceptibility to imipenem and/or meropenem presented negative results for blaSPM-1, blaIMP-1, blaVIM , and blaKPC genes. Our results indicate an unexpected low level of antimicrobial resistance and a high genotypic diversity among P. aeruginosa from Brazilian chronic CF patients.

Prevalence and Antimicrobial Resistance of Salmonella and Escherichia coli from Australian Cattle Populations at Slaughter

Antimicrobial agents are used in cattle production systems for the prevention and control of bacteria associated with diseases. Australia is the world's third largest exporter of beef; however, this country does not have an ongoing surveillance system for antimicrobial resistance (AMR) in cattle or in foods derived from these animals. In this study, 910 beef cattle, 290 dairy cattle, and 300 veal calf fecal samples collected at slaughter were examined for the presence of Escherichia coli and Salmonella, and the phenotypic AMR of 800 E. coli and 217 Salmonella isolates was determined. E. coli was readily isolated from all types of samples (92.3% of total samples), whereas Salmonella was recovered from only 14.4% of samples and was more likely to be isolated from dairy cattle samples than from beef cattle or veal calf samples. The results of AMR testing corroborate previous Australian animal and retail food surveys, which have indicated a low level of AMR. Multidrug resistance in Salmonella isolates from beef cattle was detected infrequently; however, the resistance was to antimicrobials of low importance in human medicine. Although some differences in AMR between isolates from the different types of animals were observed, there is minimal evidence that specific production practices are responsible for disproportionate contributions to AMR development. In general, resistance to antimicrobials of critical and high importance in human medicine was low regardless of the isolate source. The low level of AMR in bacteria from Australian cattle is likely a result of strict regulation of antimicrobials in food animals in Australia and animal management systems that do not favor bacterial disease.

E. coli Bacteremia Strains - High diversity and Associations with Agerelated Clinical Phenomena

Advanced age is associated with an increased proportion of Escherichia coli in bacteremia as well as an increased risk of death from E. coli blood stream infection. Age-associated differences in normal flora E. coli indicate that elderly persons may be diseased by other groups of E. coli than do younger patients. We studied a historical cohort of 212 patients with community-acquired E. coli bacteremia. The bacterial strains were tested for antimicrobial resistance and analyzed by a generic Multi-Locus Variable-Tandem Repeats Analysis (MLVA). The available 212 strains showed a great diversity, and clustered into ten different MLVA-type complexes (MTC). MTC-b, containing 97 of the strains, was associated with ≥1 comorbid illness (OR 2.02, 95% CI 1.12-3.64), and with to ≥1 atypical symptom (OR 0.46, 95% CI 0.27-0.80). MTC-c, containing 31 strains, was associated with urinary origin of infection (OR 3.28, 95% CI 1.345-8.00) and was preventive against gastrointestinal origin of infection (OR 0.11, 95% CI 0.01-0.83). MTC-g, containing only eight strains, was associated with leukopenia (OR 6.43, 95% CI 1.15-36.00). The strains showed low level of antimicrobial resistance. Fifteen of the 212 patients (7.1%) died within 14 days after admission to hospital. Neither MTC nor antimicrobial resistance was associated with hospital mortality. In conclusion, our study showed a great degree of diversity of the strains and that one of the MTCs was associated with age-related clinical phenomena. None of the MTCs were associated with outcome, indicating that patient characteristics are more important than microbial characteristics.

Bacteremia in Swedish hematological patients with febrile neutropenia: Bacterial spectrum and antimicrobial resistance patterns

The etiology of bacteremia in hematological patients with febrile neutropenia differs geographically and changes over time. Since efficient empirical antibiotic treatment depends on relevant knowledge of the bacterial panorama, the aim of this study was to describe the prevalence of bacteremia, the bacterial spectrum, and the resistance patterns of the isolates in this group today. In a cross-sectional study, routine blood cultures from febrile episodes occurring in adult patients with hematological disorders and neutropenia presenting to Karolinska University Hospital, Stockholm, Sweden during a 24-month period, were analyzed. A total of 142 febrile neutropenic episodes occurring in 124 hematological patients were included in the study. Bacteremia was documented in 27% of the episodes, and of these, 58% were due to Gram-positive pathogens. The most common isolates were viridans streptococci, coagulase-negative staphylococci, and Escherichia coli. Low levels of antibiotic resistance were detected. The underlying diagnosis of non-Hodgkin's lymphoma (NHL) was independently negatively associated with documented bacteremia (p < 0.01). The prevalence of bacteremia and the bacterial spectrum were consistent with recent Scandinavian reports. Substantially lower levels of antimicrobial resistance were registered compared to those found in other European centers. Patients with NHL were less likely to have documented bacteremia in this study.

Low level of antimicrobial resistance in Escherichia coli among Swedish nursing home residents

Screening for bacterial colonization and antimicrobial resistance (AMR) among a defined population could aid in the identification of at-risk populations and provide targets for antibiotic stewardship and infection control programmes. Two hundred and sixty-eight participants at 11 Swedish nursing homes underwent serial screening for colonization with Escherichia coli between March 2008 and September 2010. Seventy-two of the 268 participants (27%) were male. The median age was 85 y. Samples were collected from urine, the rectal mucosa, the groin, and active skin lesions. Two hundred and nine of 268 participants (78%) were colonized with E. coli at any body site/fluid. The specific colonization rates were 81% (rectum), 48% (urine), 30% (groin), 59% (unknown), and 13% (skin lesion). An antibiotic-resistant E. coli isolate was identified in 18% of all participants regardless of colonization status; all together, 87 resistant isolates were detected. Only 1 participant carried isolates with resistance to third-generation cephalosporins (cefotaxime and ceftazidime). The presence of resistance was generally low, and the greater part of the resistant cases was connected with 3 common antibiotics: ampicillin, trimethoprim/sulfamethoxazole, and ciprofloxacin. In spite of generally increasing resistance against third-generation cephalosporins in E. coli in Sweden, this study does not implicate residence at a Swedish nursing home as a risk factor for the acquisition of expressed cephalosporin resistance.

Genetic diversity and antimicrobial resistance among isolates of Escherichia coli O157: H7 from feces and hides of super-shedders and low-shedding pen-mates in two commercial beef feedlots

BackgroundCattle shedding at least 104 CFU Escherichia coli O157:H7/g feces are described as super-shedders and have been shown to increase transmission of E. coli O157:H7 to other cattle in feedlots. This study investigated relationships among fecal isolates from super-shedders (n = 162), perineal hide swab isolates (PS) from super-shedders (n = 137) and fecal isolates from low-shedder (< 104 CFU/g feces) pen-mates (n = 496) using pulsed-field gel electrophoresis (PFGE). A subsample of these fecal isolates (n = 474) was tested for antimicrobial resistance. Isolates of E. coli O157:H7 were obtained from cattle in pens (avg. 181 head) at 2 commercial feedlots in southern Alberta with each steer sampled at entry to the feedlot and prior to slaughter.ResultsOnly 1 steer maintained super-shedder status at both samplings, although approximately 30% of super-shedders in sampling 1 had low-shedder status at sampling 2. A total of 85 restriction endonuclease digestion clusters (REPC; 90% or greater similarity) and 86 unique isolates (< 90% similarity) were detected, with the predominant REPC (30% of isolates) being isolated from cattle in all feedlot pens, although it was not associated with shedding status (super- or low-shedder; P = 0.94). Only 2/21 super-shedders had fecal isolates in the same REPC at both samplings. Fecal and PS isolates from individual super-shedders generally belonged to different REPCs, although fecal isolates of E. coli O157:H7 from super- and low-shedders showed greater similarity (P < 0.001) than those from PS. For 77% of super-shedders, PFGE profiles of super-shedder fecal and PS isolates were distinct from all low-shedder fecal isolates collected in the same pen. A low level of antimicrobial resistance (3.7%) was detected and prevalence of antimicrobial resistance did not differ among super- and low-shedder isolates (P = 0.69), although all super-shedder isolates with antimicrobial resistance (n = 3) were resistant to multiple antimicrobials.ConclusionsSuper-shedders did not have increased antimicrobial resistance compared to low-shedder pen mates. Our data demonstrated that PFGE profiles of individual super-shedders varied over time and that only 1/162 steers remained a super-shedder at 2 samplings. In these two commercial feedlots, PFGE subtypes of E. coli O157:H7 from fecal isolates of super- and low-shedders were frequently different as were subtypes of fecal and perineal hide isolates from super-shedders.

Bacteremia In Hospitalized Patients with Malignant Blood Disorders: a Retrospective Comparative Study of Causative Agents and Antimicrobial Susceptibility Profiles

AbstractAbstract 4868 Introduction:Bacteremia is a major cause of morbidity and mortality in patients with hematological disorders during chemotherapy-induced neutropenia. Initial antimicrobial treatment is chosen empirically. Increasing antimicrobial resistance is a global obstacle for improving outcome for hematological patients. The aim of this study was to compare temporal trends in species distribution and antimicrobial susceptibility in bacteremic patients hospitalized in a hematology ward at Karolinska University Hospital, Stockholm, Sweden, over a 21-year period. Materials and methods:A total of 794 clinically significant isolates, 667 clinical episodes of bacteremia in 463 patients were identified during the last 7 years and the results were compared with those published from the same ward during the preceding 14 years. Isolates and episodes were identified from the laboratory information system, which has been in use during the entire 21-year period. For coagulase-negative staphylococci (CoNS), Corynebacterium spp., Propionibacterium spp. and Bacillus spp. bacteremia was considered significant only if the isolates were detected in two or more blood specimens. No major changes in patient selection were introduced during these 21 years and quinolone prophylaxis was used only to a very limited extent. Results:Any shift between Gram-negative and Gram-positive bacteria has not been noted at any time and the proportion of Gram-positive isolates has remained at a level of 53–55%. In the last 7-year period the male patient predominance increased from 58% to 62%, and the median age increased from 58 to 62 years. The 7- and 30-day crude mortality rates were 5.3% and 14.8%, respectively, compared with 6.3% and 16% in the preceding 7-year period (p>0.05). Polymicrobial bacteremia, defined as growth of more than one organism during the same bacteremic episode within 24 hours or 72 hours, was seen in 13.7% and 14.8% of patients respectively, compared to 11% (24 hours) in the preceding 7-year period (p>0.05). Polymicrobial bacteremia was seen in 25% and 28% respectively of patients who died within 7 days. Crude mortality at day 7 in patients with polymicrobial bacteremia was significantly higher than for patients with monomicrobial bacteremia (p=<0.0001).As in the previous periods the dominating pathogens were Escherichia coli (18%), CoNS (15%), viridans streptococci (14%) and Klebsiella spp. (10%). A significant increase of Enterobacter spp. (from 3.1 to 5.4%) and decrease of Staphylococcus aureus (from 10 to 6.9%) was seen compared with the middle 7-year period. Enterococcus faecium increased during the middle 7-year period and has remained frequent and stable at 8%.In E. coli resistance to piperacillin-tazobactam (TZP) was 9.2%, ciprofloxacin (CIP) 8.5% and ceftazidime (CAZ) 2.1%, whereas no resistance was observed to imipenem-cilastatin (IPM). In Klebsiella spp. resistance to TZP was 9.0%, CIP 1.3% and CAZ 1.3%, whereas no resistance was observed to IPM. Among Enterobacter spp. resistance to TZP was 26%, CAZ 26%, IPM 2.3% and CIP 4.7%. In P. aeruginosa resistance to IPM was 12%, TZP 4.8% and CIP 7.1%, whereas no CAZ-resistant strains were found. Among CoNS resistance to isoxazolyl-penicillin was 71% in the last period, compared to 58% in the middle period. Only one isolate of E. faecium (cultured in the last 7-year period) was resistant to vancomycin. Two methicillin-resistant S. aureus were detected in the last 7-year period. Resistance to benzyl-penicillin among viridans streptococci was 20% in the last 7-year period and 12% in the middle 7-year period. Only the increase in CIP resistance in E. coli during the last 7-year period was statistically significant (p= 0.02). Conclusions:We observed a stable distribution of species and a low rate of antimicrobial resistance during a period of 21 years. In the last 7-year period a significant increase in CIP-resistance was observed in E. coli. This finding can possibly be related to a very limited use of antibacterial prophylaxis in our centre, but also reflects the general low level of antimicrobial resistance in Sweden. Crude mortality was unchanged during the study period. Mortality was higher in patients with poly- th. Disclosures:No relevant conflicts of interest to declare.