Comparison of hospital-wide and unit-specific cumulative antibiograms in hospital- and community-acquired infection

Spanish Antibiogram Committee (COESANT) recommendations for cumulative antibiogram reports

The Spanish Antibiogram Committee (Comité Español del Antibiograma, COESANT) presents in this document a series of recommendations intending to unify how cumulative antibiogram reports must be made in Clinical Microbiology Spanish laboratories. This article is based on the information included in the Clinical Microbiology Procedure No. 51, «Preparation of cumulative reports on antimicrobial susceptibility» of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), published in 2014. The recommendations also include the modifications in the definition of clinical interpretive categories recently published by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) in 2019. Its final objective is to establish a homogeneous way of preparing these summaries to compare results from different centers or aggregate the information from these in order to carry out an adequate local or even national surveillance regarding the evolution of antimicrobial susceptibility.

Influence of hospital size on antimicrobial resistance and advantages of restricting antimicrobial use based on cumulative antibiograms in dogs with Staphylococcus pseudintermedius infections in Japan

Background

Antimicrobial resistance in Staphylococcuspseudintermedius (SP) and the prevalence of meticillin‐resistant SP (MRSP) is increasing in dogs worldwide.

Objectives

To evaluate the influence of hospital size on antimicrobial resistance of SP and whether restricted use of antimicrobials based on antibiograms could reduce the identification of antimicrobial resistance in SP from infected dogs.

Methods and materials

In Study 1, a total of 2,294 SP isolates from dogs with pyoderma (n = 1,858, 52 hospitals) or otitis externa (OE; n = 436, 44 hospitals) taken between 2017 and 2019 were analysed. Clinics were categorised into small, medium and large based on numbers of practicing veterinary surgeons. In Study 2, a cumulative antibiogram was constructed for 12 antimicrobials from one large veterinary clinic from 2017 to 2018. Referring to this antibiogram, the clinic introduced strict antimicrobial selection criteria to treat dogs with pyoderma and OE, starting in 2018.

Results

MRSP was identified in 981 dogs (42.8%). In large clinics, the isolation rate of MRSP was 51.1% (404 of 791), which was significantly higher (P < 0.01) than in small clinics with less than two veterinary practitioners (34.0%, 154 of 453). In the antibiogram study, the susceptibility rates of oxacillin (MPIPC, 61.5%), cefpodoxime (CPDX, 55.8%) and minocycline (MINO, 55.8%) were significantly higher in 2019 (n = 52) than in 2017 to 2018 (n = 54; MPIPC, 37.0%; CPDX, 33.3%; MINO, 20.4%; P < 0.05).

Conclusions and clinical relevance

Hospital size could affect the isolation rate of MRSP in dogs. Restricted use of antimicrobials for over a year based on cumulative antibiograms could reduce the resistance rate of multiple antimicrobials in SP isolated from dogs with pyoderma and OE.

Background – Antimicrobial resistance in Staphylococcuspseudintermedius (SP) and the prevalence of meticillin‐resistant SP (MRSP) is increasing in dogs worldwide. Objectives: To evaluate the influence of hospital size on antimicrobial resistance of SP and whether restricted use of antimicrobials based on antibiograms could reduce the identification of antimicrobial resistance in SP from infected dogs. Conclusions and clinical relevance – Hospital size could affect the isolation rate of MRSP in dogs. Restricted use of antimicrobials for over a year based on cumulative antibiograms could reduce the resistance rate of multiple antimicrobials in SP isolated from dogs with pyoderma and OE.

Antimicrobial-resistant pathogens in Canadian ICUs: results of the CANWARD 2007 to 2016 study

OBJECTIVES

To describe the microbiology and antimicrobial resistance patterns of cultured samples acquired from Canadian ICUs.

METHODS

From 2007 to 2016, tertiary care centres from across Canada submitted 42938 bacterial/fungal isolates as part of the CANWARD surveillance study. Of these, 8130 (18.9%) were from patients on ICUs. Susceptibility testing guidelines and MIC interpretive criteria were defined by CLSI.

RESULTS

Of the 8130 pathogens collected in this study, 58.2%, 36.3%, 3.1% and 2.4% were from respiratory, blood, wound and urine specimens, respectively. The top five organisms collected from Canadian ICUs accounted for 55.4% of all isolates and included Staphylococcus aureus (21.5%), Pseudomonas aeruginosa (10.6%), Escherichia coli (10.4%), Streptococcus pneumoniae (6.5%) and Klebsiella pneumoniae (6.4%). MRSA accounted for 20.7% of S. aureus collected, with community-associated (CA) MRSA genotypes increasing in prevalence over time (P < 0.001). The highest susceptibility rates among MRSA were 100% for vancomycin, 100% for ceftobiprole, 100% for linezolid, 99.7% for ceftaroline, 99.7% for daptomycin and 99.7% for tigecycline. The highest susceptibility rates among E. coli were 100% for tigecycline, 99.9% for meropenem, 99.7% for colistin and 94.2% for piperacillin/tazobactam. MDR was identified in 26.3% of E. coli isolates, with 10.1% producing an ESBL. The highest susceptibility rates among P. aeruginosa were 97.5% for ceftolozane/tazobactam, 96.1% for amikacin, 94.7% for colistin and 93.3% for tobramycin.

CONCLUSIONS

The most active agents against Gram-negative bacilli were the carbapenems, tigecycline and piperacillin/tazobactam. Against Gram-positive cocci, the most active agents were vancomycin, daptomycin and linezolid. The prevalence of CA-MRSA genotypes and ESBL-producing E. coli collected from ICUs increased significantly over time.

Intra-hospital differences in antibiotic use correlate with antimicrobial resistance rate in Escherichia coli and Klebsiella pneumoniae: a retrospective observational study

Background

Monitoring antimicrobial use and resistance in hospitals are important tools of antimicrobial stewardship programs. We aimed to determine the association between the use of frequently prescribed antibiotics and the corresponding resistance rates in Escherichia coli and Klebsiella pneumoniae among the clinical departments of a tertiary care hospital.

Methods

We performed a retrospective observational study to analyse the use of nine frequently prescribed antibiotics and the corresponding antimicrobial resistance rates in hospital acquired E. coli and K. pneumoniae isolates from 18 departments of our institution over 9 years (2008–2016). The main cross-sectional analysis assessed the hypothetical influence of antibiotic consumption on resistance by mixed logistic regression models.

Results

We found an association between antibiotic use and resistance rates in E. coli for amoxicillin-clavulanic acid (OR per each step of 5 defined daily dose/100 bed-days 1.07, 95% CI 1.02–1.12; p = 0.004), piperacillin-tazobactam (OR 2.11, 95% CI 1.45–3.07; p < 0.001), quinolones (OR 1.52, 95% CI 1.25–1.86; p < 0.001) and trimethoprim-sulfamethoxazole (OR 1.59, 95% CI 1.19–2.13; p = 0.002). Additionally, we found a significant association when all nine antibiotics were combined in one analysis. The association between consumption and resistance rates was stronger for nosocomial than for community strains. In K. pneumoniae, we found an association for amoxicillin-clavulanic acid (OR 1.07, 95% CI 1.01–1.14; p = 0.025) and for trimethoprim-sulfamethoxazole (OR 2.02, 95% CI 1.44–2.84; p < 0.001). The combined analysis did not show an association between consumption and resistance (OR 1.06, 95% CI 0.99–1.14; p = 0.07).

Conclusions

We documented an association between antibiotic use and resistance rate for amoxicillin-clavulanic acid, piperacillin-tazobactam, quinolones and trimethoprim-sulfamethoxazole in E. coli and for amoxicillin-clavulanic acid and trimethoprim-sulfamethoxazole in K. pneumoniae across different hospital departments. Our data will support stewardship interventions to optimize antibiotic prescribing at a department level.

Electronic supplementary material

The online version of this article (10.1186/s13756-018-0387-0) contains supplementary material, which is available to authorized users.

Antimicrobial Stewardship in Long-Term Care Facilities: Approaches to Creating an Antibiogram when Few Bacterial Isolates Are Cultured Annually

Antibiograms are important clinical tools to report and track antibiotic susceptibility and help guide empiric antimicrobial therapy. Antibiograms support compliance with antimicrobial stewardship (AMS) requirements from the Centers for Medicare and Medicaid Services and are in line with recommendations from the Centers for Disease Control and Prevention Core Elements of AMS for nursing homes/long-term care facilities (LTCFs). Unlike most acute-care settings, LTCFs are challenged in creating antibiograms because of the low number of bacterial isolates collected annually. Determining the best methodology for creating clinically useful antibiograms for LTCFs needs to be explored. Possible approaches include (1) extending the isolate data beyond 1 year, (2) combining isolate data from the same geographic region, (3) using a nearby acute-care facility's antibiogram as a proxy, or (4) collapsing isolate data. This article discusses the benefits and limitations of each approach.

Comparison of antibiotic susceptibility of Escherichia coli in urinary isolates from an emergency department with other institutional susceptibility data

PURPOSE

The antibiotic susceptibility of Escherichia coli in isolates from patients with uncomplicated urinary tract infection (UTI) in an emergency department (ED) was compared with susceptibility data from the associated hospital.

METHODS

Patients eligible for study participation included women age 18-65 years with one or more symptoms consistent with a UTI for whom a urine dipstick, urinalysis, or urine culture was ordered. Clinical decision-making, including the decision to order a urine culture, was at the discretion of the individual healthcare provider; however, a deidentified urine culture and antimicrobial susceptibility testing were performed for those study participants for whom a urine culture was not ordered. We compared the E. coli-specific antibiogram for uncomplicated UTI to the antibiogram based on all urine cultures in the ED regardless of patient disposition, non-intensive care unit (ICU) hospital inpatients, and the hospitalwide antibiogram.

RESULTS

Of the 578 ED patients screened for study eligibility, 119 met the inclusion criteria. E. coli, detected in 53 (74%) of the 72 pathogen-positive cultures, was the most common pathogen isolated. For E. coli, ciprofloxacin nonsusceptibility was significantly less common in isolates from ED patients with uncomplicated cystitis and pyelonephritis than in isolates from non-ICU inpatients or from the hospitalwide population. E. coli nonsusceptibility to ciprofloxacin was significantly less common in ED isolates from patients with uncomplicated UTI than in isolates from all ED patients with clinician-ordered urine cultures.

CONCLUSION

Antibiotic susceptibility of E. coli in an ED and its associated hospital depended on factors such as whether patients were hospitalized and whether ED isolates were from patients with uncomplicated UTI.

Solid organ transplant antibiograms: an opportunity for antimicrobial stewardship

OBJECTIVES

We aimed to compare the antimicrobial susceptibility percentages in blood and urine bacterial isolates recovered from solid organ transplant (SOT) recipients with those reported in the hospital-wide antibiogram.

METHODS

Retrospective review of the antimicrobial susceptibilities of bacterial isolates recovered from SOT recipients at a 1550-bed hospital over a 2-year period. Antibiograms were categorized by anatomic site (blood and urine). Percentage of bacterial susceptibilities to specific antibiotics were compared with the hospital-wide antibiogram.

RESULTS

A total of 1889 unique cultures were identified. Blood and urine isolates of Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa had significantly lower susceptibility to first and second line antibiotics compared to the hospital-wide antibiogram.

CONCLUSION

Significant differences in susceptibilities between isolates from blood and urine cultures from SOT recipients and the hospital-wide antibiogram were found. A population-based strategy for the development of antibiograms specific for this group of high-risk patients could better guide appropriate empiric antimicrobial selection.

Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data--The Influence of Different Parameters in a Routine Clinical Microbiology Laboratory

Introduction

Many clinical microbiology laboratories report on cumulative antimicrobial susceptibility testing (cAST) data on a regular basis. Criteria for generation of cAST reports, however, are often obscure and inconsistent. Whereas the CLSI has published a guideline for analysis and presentation of cAST data, national guidelines directed at clinical microbiology laboratories are not available in Europe. Thus, we sought to describe the influence of different parameters in the process of cAST data analysis in the setting of a German routine clinical microbiology laboratory during 2 consecutive years.

Material and Methods

We developed various program scripts to assess the consequences ensuing from different algorithms for calculation of cumulative antibiograms from the data collected in our clinical microbiology laboratory in 2013 and 2014.

Results

One of the most pronounced effects was caused by exclusion of screening cultures for multi-drug resistant organisms which decreased the MRSA rate in some cases to one third. Dependent on the handling of duplicate isolates, i.e. isolates of the same species recovered from successive cultures on the same patient during the time period analyzed, we recorded differences in resistance rates of up to 5 percentage points for S. aureus, E. coli and K. pneumoniae and up to 10 percentage points for P. aeruginosa. Stratification by site of care and specimen type, testing of antimicrobials selectively on resistant isolates, change of interpretation rules and analysis at genus level instead of species level resulted in further changes of calculated antimicrobial resistance rates.

Conclusion

The choice of parameters for cAST data analysis may have a substantial influence on calculated antimicrobial resistance rates. Consequently, comparability of cAST reports from different clinical microbiology laboratories may be limited. We suggest that laboratories communicate the strategy used for cAST data analysis as long as national guidelines for standardized cAST data analysis and reporting do not exist in Europe.

Cumulative Antimicrobial Susceptibility Data from Intensive Care Units at One Institution: Should Data Be Combined?

Cumulative susceptibility test data (CSTD) are used to guide empirical antimicrobial therapy and to track trends in antibiotic resistance. The Clinical and Laboratory Standards Institute recommends reporting CSTD at least annually and sets the minimum number of isolates per reported organism at 30. To comply, many hospitals combine data from multiple intensive care units (ICUs); however, this may not be appropriate to guide empirical therapy because of variations in patient populations. In this study, susceptibility data for two different ICUs at a tertiary care hospital in Toronto, Canada, were used to create a traditional CSTD report, which combined data from different ICUs, and a rolling-average CSTD report, which pooled 2 years of data for each ICU separately. For simplicity, data for only the most common Gram-negative organisms (Escherichia coli,Pseudomonas aeruginosa) and the most relevant antibiotics (ciprofloxacin, piperacillin-tazobactam) were examined. With the rolling-average method, significant differences in susceptibility were seen between the ICUs in 50% of the organism-antimicrobial combinations. Furthermore, the 3% median year-over-year difference in susceptibilities seen for the 16 organism-antibiotic combinations by using the traditional method was lower than the 14% median difference seen for the 20 between-ICU within-year comparisons obtained using the rolling-average method. Changes in our selection of empirical antibiotics resulted from this revised approach, and our results suggest that pooling data from ICUs with different patient populations may not be appropriate. A rolling-average method may be an appropriate strategy for the creation of individual-unit CSTD reports.

[Antimicrobial susceptibility cumulative reports]

Cumulative reports on antimicrobial susceptibility tests data are important for selecting empirical treatments, as an educational tool in programs on antimicrobial use, and for establishing breakpoints defining clinical categories. These reports should be based on data validated by clinical microbiologists using diagnostic samples (not surveillance samples). In order to avoid a bias derived from including several isolates obtained from the same patient, it is recommended that, for a defined period, only the first isolate is counted. A minimal number of isolates per species should be presented: a figure of >=30 isolates is statistically acceptable. The report is usually presented in a table format where, for each cell, information on clinically relevant microorganisms-antimicrobial agents is presented. Depending on particular needs, multiple tables showing data related to patients, samples, services or special pathogens can be prepared.

Homogeneity of antimicrobial policy, yet heterogeneity of antimicrobial resistance: antimicrobial non-susceptibility among 108,717 clinical isolates from primary, secondary and tertiary care patients in London

OBJECTIVES

We examined the 4 year trend in antimicrobial susceptibilities and prescribing across levels of care at two London teaching hospitals and their multisite renal unit, and for the surrounding community.

METHODS

Laboratory and pharmacy information management systems were interrogated, with antimicrobial use and susceptibilities analysed between hospitals, within hospitals and over time.

RESULTS

A total of 108,717 isolates from 71,687 patients were identified, with significant differences (at P < 0.05) in antimicrobial susceptibility between and within hospitals. Across the 4 years, rates of ESBL-/AmpC-producing Enterobacteriaceae ranged from 6.4% to 10.7% among community isolates, 17.8% to 26.9% at ward level and 25.2% to 52.5% in critical care. Significant variations were also demonstrated in glycopeptide-resistant enterococci (ward level 6.2%-17.4%; critical care 21.9%-56.3%), MRSA (ward level 18.5%-38.2%; critical care 12.5%-47.9%) and carbapenem-resistant Pseudomonas spp. (ward level 8.3%-16.9%; critical care 19.9%-53.7%). Few instances of persistently higher resistance were seen between the hospitals in equivalent cohorts, despite persistently higher antimicrobial use in Hospital 1 than Hospital 2. We found significant fluctuations in non-susceptibility year on year across the cohorts, but with few persistent trends.

CONCLUSIONS

The marked heterogeneity of antimicrobial susceptibilities between hospitals, within hospitals and over time demands detailed, standardized surveillance and appropriate benchmarking to identify possible drivers and effective interventions. Homogeneous antimicrobial policies are unlikely to continue to be suitable as individual hospitals join hospital networks, and policies should be tailored to local resistance rates, at least at the hospital level, and possibly with finer resolution, particularly for critical care.

Epidemiology and antimicrobial resistance among commonly encountered bacteria associated with infections and colonization in intensive care units in a university-affiliated hospital in Shanghai

BACKGROUND/PURPOSE

The aim of this study was to classify intensive care unit (ICU) bacterial strains as either ICU-acquired or ICU-on-admission and to compare their epidemiological and antibiogram characteristics.

METHODS

The study was performed in a 1300-bed university-affiliated hospital from January 1, 2006 to December 31, 2010. Based on the time of ICU admission, ICU isolates were classified as ICU-acquired strains (appearing more than 48 hours after admission) or ICU-on-admission strains (appearing 48 hours or less from admission). The microbiological data before ICU admission, the microbiological data, and susceptibility testing were compared between the ICU-acquired and ICU-on-admission bacterial isolates.

RESULTS

The most common ICU-acquired strains were Acinetobacter baumannii (19.5%), Pseudomonas aeruginosa (15.6%), Stenotrophomonas maltophilia (11.5%), Staphylococcus aureus (10.7%), Enterococcus spp. (10.6%), and Klebsiella pneumoniae (9.7%). There were significant differences between ICU-acquired and ICU-on-admission isolates in the susceptibility rates of Gram-negative bacteria to antibiotics, especially the susceptibility of A. baumannii to imipenem [23.8% (ICU-acquired) vs. 44.4% (ICU-on-admission), p < 0.001] and meropenem (24.1% vs. 37.8%, p < 0.001), and the susceptibility of P. aeruginosa to imipenem (39.3% vs. 76.1%, p < 0.001) and meropenem (58.5% vs. 76.1%, p < 0.05). Furthermore, decreased susceptibility rates of A. baumannii and P. aeruginosa to carbapenems were correlated with an extended ICU stay (p < 0.05).

CONCLUSION

Because of decreasing susceptibility rates of pathogens (especially ICU-acquired strains) and a significant correlation with the length of ICU stay, intensivists should consider a patient's time of ICU admission and previous microbiological data and should distinguish ICU-acquired strains from non-ICU-acquired strains so as to initiate optimized empirical antibiotic therapy against ICU-acquired infections.