Clinicians' interpretation of thresholds in hospital antibiograms for gram-negative rod infections: A survey and contingent valuation study of hospitalists

Clinical guidelines suggest that hospital antibiograms are a key component when deciding empiric therapy, but little is known about how often clinicians use antibiograms and how they influence clinicians' empiric therapy decisions. We surveyed hospitalists at seven healthcare systems in the United States on their reported practices related to antibiograms and their hypothetical prescribing for four clinical scenarios associated with gram-negative rod pathogens. Each was given a randomly assigned antibiogram susceptibility percentage, and we used contingent valuation analysis to assess whether the antibiogram susceptibility percentage was associated with prescribing practices. Of the 193 survey responders, only 52 (26.9%) respondents reported using antibiograms more than monthly. Across all four clinical scenarios, there was no evidence that antibiogram susceptibility levels influenced antibiotic prescribing practices. With limited utilization and no evidence that they influenced practice, antibiograms may have a limited role in hospitalist care delivery for common gram-negative rod infections.

Application of Precision Medicine Concepts in Ambulatory Antibiotic Management of Acute Pyelonephritis

Acute pyelonephritis (APN) is a relatively common community-acquired infection, particularly in women. The early appropriate antibiotic treatment of this potentially life-threatening infection is associated with improved outcomes. The international management guidelines for complicated urinary tract infections and APN recommend using oral antibiotics with <10% resistance among urinary pathogens. However, increasing antibiotic resistance rates among Escherichia coli and other Enterobacterales to fluoroquinolones, trimethoprim-sulfamethoxazole (TMP-SMX), and beta-lactams has left patients without reliable oral antibiotic treatment options for APN. This narrative review proposes using precision medicine concepts to improve empirical antibiotic therapy for APN in ambulatory settings. Whereas resistance rates to a particular antibiotic class may exceed 10% at the population-based level, the predicted antibiotic resistance rates based on patient-specific risk factors fall under 10% in many patients with APN on the individual level. The utilization of clinical tools for the prediction of fluoroquinolones, TMP-SMX, and third-generation cephalosporin resistance improves the ambulatory antibiotic management of APN. It may also reduce the need to switch antibiotic therapy later based on the in vitro antibiotic susceptibility testing results of bacterial isolates in urinary cultures. This approach may mitigate the burden of increasing antibiotic resistance in the community by ensuring that the initial antibiotic prescribed has the highest likelihood of treating APN appropriately.

Deficiencies of Rule-Based Technology-Generated Antibiograms for Specialized Care Units

The objective of this study was to compare the pathogens and susceptibilities of the current automated, rule-based technology (RBT) antibiogram with one manually collected through chart review with additional rules applied. This study was a two-year, retrospective cohort study and included all bacterial cultures within the first 30 days from patients admitted to a single Burn Center. The current RBT antibiogram served as the control, and new antibiogram versions were created using additional rules and compared to the control. Six-hundred fifty-seven patients were admitted (61% excluded for lack of cultures). 59% had at least one hospital-acquired risk factor, with over one-third having recent illicit drug use and one-third having a recent hospitalization. Of the 410 cultures included, 57% were Gram-negative, and half were from wound infections. Sensitivities were significantly different when comparing the manual and the RBT version after including factors such as days since admission, presence of hospital-acquired risk factors, or previous antibiotic courses. Recommended empiric Gram-negative antibiotics changed from double coverage to a single β-lactam with >90% susceptibility. The susceptibilities between the first and subsequent courses were dramatically different. Before developing an antibiogram or interpreting the output, it is important to consider which automated criteria are utilized, especially for units with extended lengths of stay.

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.

Antibiotic Susceptibility of Bacterial Pathogens Stratified by Age in a Public Hospital in Qassim

Antibiotics have completely transformed medical practice by enabling the treatment of infections that were formerly fatal. However, misuse of antibiotics encourages the formation and spread of germs that are resistant to therapy, hastening the emergence of bacterial resistance. This was a retrospective study that aimed to gather information about the variation in bacterial susceptibility of various patient age groups in a public hospital in Qassim, Saudi Arabia from January 2020 to December 2021. The study included reviewing bacterial susceptibility results that were collected from the laboratory department of the hospital. Four thousand seven hundred and sixty-two isolates were collected. The age of 46.41% of the patients was more than 63 years and the age of 28.96% of the patients was less than 48 years. The most prevalent bacteria were Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae. The resistance of gram-positive and gram-negative bacteria to different antibiotics in the elderly group was generally higher than the resistance rates in younger patients. For example, in patients less than 48 years old, the resistance of Staphylococcus haemolyticus to clindamycin (53.3%), ampicillin (91.4%), ciprofloxacin (68.2%), erythromycin (86.1%), and penicillin (93.18%) was high. In patients aged more than 63 years, Staphylococcus haemolyticus was highly resistant to sulfamethoxazole (54.8%), clindamycin (63.9%), ampicillin (98.1%), ciprofloxacin (79.1%), erythromycin (93.2%), gentamicin (63.6%), and penicillin (98.7%). Before prescribing the antibiotics, it is important to assess the microbes that patients have and to be aware of the bacterial isolates’ patterns of antibiotic susceptibility among patients of various age groups.

Guidelines on Implementing Antimicrobial Stewardship Programs in Korea

These guidelines were developed as a part of the 2021 Academic R&D Service Project of the Korea Disease Control and Prevention Agency in response to requests from healthcare professionals in clinical practice for guidance on developing antimicrobial stewardship programs (ASPs). These guidelines were developed by means of a systematic literature review and a summary of recent literature, in which evidence-based intervention methods were used to address key questions about the appropriate use of antimicrobial agents and ASP expansion. These guidelines also provide evidence of the effectiveness of ASPs and describe intervention methods applicable in Korea.

Antibiotics' susceptibility patterns of bacterial isolates causing lower respiratory tract infections in ICU patients at referral hospitals in Namibia

BACKGROUND

Lower respiratory tract infections (LRTIs) are a particular public health concern especially among sub-Saharan African countries. This is especially the case in Namibia, where LRTIs are currently the third leading cause of death, 300 deaths in children under 5 years of age. To reduce the burden of LRTIs on health systems and ensure appropriate patient management, it is critical to know the most prevalent pathogens leading to LRTIs and their susceptibility patterns in the local setting. Consequently, the objective of this study was to formulate cumulative antibiograms for Intensive Care Units (ICUs) of referral hospitals in Namibia to guide future antibiotic use.

METHODS

A retrospective analytical cross-sectional study was conducted over 2 years. The cumulative antibiograms were constructed in accordance with current guidelines.

RESULTS

A total of 976 first isolate cultures were obtained from ICUs of the different referral hospitals. K. pneumoniae (8.8%, 8.1%) was a predominant pathogen in Windhoek Central hospital ICU in 2017 and 2018. In Oshakati intermediate hospital ICU, Enterobacter sp. (22.2%) and P. aeruginosa (37.5%) were the common pathogens in 2017 and 2018, respectively. A. baumannii isolates were >90% susceptibility to colistin, carbapenems, and tigecycline in 2017. In 2017, K. pneumoniae isolates were more susceptible to carbapenems (94% and 93.8% among isolates), amikacin (89.3%), and tigecycline (88.7%). In 2018, K. pneumoniae isolates were 100% susceptible amikacin, colistin, and carbapenems. S. maltophilia isolates were more than 80% susceptible to all the tested antibiotics. S. aureus isolates were 100% susceptible to linezolid, rifampicin, teicoplanin, and vancomycin in 2017 and in 2018. Its susceptibility to these antibiotics did not change.

CONCLUSION

The susceptibility patterns of the common isolated gram-negative pathogens were highly variable. Meropenem in combination with gentamicin is now the recommended antibiotic combination for empiric therapy for patients with LRTIs in Windhoek Central Hospital ICU.

Distribution of pathogens and antimicrobial resistance in ICU-bloodstream infections during hospitalization: a nationwide surveillance study

Changing microorganism distributions and decreasing antibiotic susceptibility over the duration of hospitalization have been described for the colonization or infection of selected organ systems. Few data are available on bacteremias in the intensive care unit (ICU) setting. We conducted a nationwide study on bloodstream infection (BSI) using data from the Swiss Centre for Antibiotic Resistance (ANRESIS). We analyzed data on BSI detected in the ICU from hospitals that sent information on a regular basis during the entire study period (2008–2017). We described specific trends of pathogen distribution and resistance during hospitalization duration. We included 6505 ICU- BSI isolates from 35 Swiss hospitals. We observed 2587 possible skin contaminants, 3788 bacteremias and 130 fungemias. The most common microorganism was Escherichia coli (23.2%, 910), followed by Staphylococcus aureus (18.7%, 734) and enterococci (13.1%, 515). Enterococcus spp (p < 0.0001) and Candida spp (p < 0.0001) increased in proportion, whereas E. coli (p < 0.0001) and S. aureus (p < 0.0001) proportions decreased during hospitalization. Resistances against first- and second-line antibiotics increased linearly during hospitalization. Pathogen distribution and antimicrobial resistance in ICU-BSI depends on the duration of the hospitalization. The proportion of enterococcal BSI, candidemia and resistant microorganisms against first- and second-line antibiotics increased during hospitalization.

Solid organ transplant-specific antibiogram in a tertiary pediatric hospital in Canada

SOT recipients are more vulnerable to infections with antimicrobial-resistant organisms, and therefore, it may be useful for transplant centers to create transplant-specific antibiograms to direct empirical antimicrobial regimens and monitor trends in antimicrobial resistance. SOT-specific antibiograms were created using antimicrobial susceptibility data on isolates from 2012 to 2018 at The Hospital for Sick Children, Toronto, Ontario, Canada. The CLSI guidelines were followed to generate the antibiograms except that results from 2 years of data were pooled on a rolling basis to achieve larger sample sizes. The 3 most frequent organisms in one analysis period of the SOT antibiogram were Escherichia coli (average sample size ±standard deviation; n = 28.7 ± 3.8), Staphylococcus aureus (n = 27.8 ± 5.0), and Pseudomonas aeruginosa (non-CF) (n = 19.8 ± 8.8). For E.coli, susceptibilities in the SOT antibiogram were significantly lower than those in the hospital-wide antibiogram in 2017-2018 for ampicillin (27% vs 47%; p = .014), piperacillin/tazobactam (55% vs 88%; p < .001), cefotaxime (59% vs 89%; p < .001), ciprofloxacin (71% vs 88%; p = .007), and trimethoprim-sulfamethoxazole (41% vs 69%; p = .001), but not significantly different for aminoglycosides and meropenem. In the SOT antibiogram of E. coli, decreased susceptibility trend was confirmed in some antibiotics, including piperacillin/tazobactam (83% in 2012-2013 vs 55% in 2017-2018). At our center, the solid organ transplant-specific antibiogram revealed important differences in E. coli susceptibilities and trends in antimicrobial resistance. Developing a SOT antibiogram will assist in revising and improving empiric treatment guidelines as well as monitoring antimicrobial resistance in this population.

Distribution of pathogens and antimicrobial resistance in bacteraemia according to hospitalization duration: a nationwide surveillance study in Switzerland

OBJECTIVES

Changing microorganism distributions and decreasing antibiotic susceptibility with increasing length of hospital stay have been demonstrated for the colonization or infection of selected organ systems. We wanted to describe microorganism distribution or antibiotic resistance in bacteraemia according to duration of the hospitalization using a large national epidemiological/microbiological database (ANRESIS) in Switzerland.

METHODS

We conducted a nationwide, observational study on bacteraemia using ANRESIS data from 1 January 2008 to 31 December 2017. We analysed data on bacteraemia from those Swiss hospitals that sent information on a regular basis during the entire study period. We described the pathogen distribution and specific trends of resistance during hospitalization for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens and Staphylococcus aureus.

RESULTS

We included 28 318 bacteraemia isolates from 90 Swiss hospitals. The most common aetiology was E. coli (33.4%, 9459), followed by S. aureus (16.7%, 4721), K. pneumoniae (7.1%, 2005), Enterococcus faecalis (5.2%, 1473), P. aeruginosa (4.3%, 1228), Streptococcus pneumoniae (4.3%, 1208) and Enterococcus faecium (3.9%, 1101). We observed 489 (1.73%) S. marcescens isolates. We observed an increasing trend for E. faecium (from 1.5% at day 0 to 13.7% at day 30; p < 0.001), K. pneumoniae (from 6.1% to 7.8%, p < 0.001) and P. aeruginosa (from 2.9% to 13.7%, p < 0.001) with increasing duration of hospitalization; and decreasing trends for E. coli (from 41.6% to 21.6%; p < 0.001) and S. aureus (p < 0.001). Ceftriaxone resistance among E. coli remained stable for the first 15 days of hospitalization and then increased. Ceftriaxone resistance among K. pneumoniae and S. marcescens and oxacillin resistance among S. aureus increased linearly during the hospitalization. Cefepime resistance among P. aeruginosa remained stable during the hospitalization.

DISCUSSION

We showed that hospitalization duration is associated with a species- and antibiotic class-dependent pattern of antimicrobial resistance.

Linking antimicrobial resistance surveillance to antibiotic policy in healthcare settings: the COMBACTE-Magnet EPI-Net COACH project

OBJECTIVES

To systematically summarize the evidence on how to collect, analyse and report antimicrobial resistance (AMR) surveillance data to inform antimicrobial stewardship (AMS) teams providing guidance on empirical antibiotic treatment in healthcare settings.

METHODS

The research group identified 10 key questions about the link between AMR surveillance and AMS using a checklist of 9 elements for good practice in health research priority settings and a modified 3D combined approach matrix, and conducted a systematic review of published original studies and guidelines on the link between AMR surveillance and AMS.

RESULTS

The questions identified focused on AMS team composition; minimum infrastructure requirements for AMR surveillance; organisms, samples and susceptibility patterns to report; data stratification strategies; reporting frequency; resistance thresholds to drive empirical therapy; surveillance in high-risk hospital units, long-term care, outpatient and veterinary settings; and surveillance data from other countries. Twenty guidelines and seven original studies on the implementation of AMR surveillance as part of an AMS programme were included in the literature review.

CONCLUSIONS

The evidence summarized in this review provides a useful basis for a more integrated process of developing procedures to report AMR surveillance data to drive AMS interventions. These procedures should be extended to settings outside the acute-care institutions, such as long-term care, outpatient and veterinary. Without proper AMR surveillance, implementation of AMS policies cannot contribute effectively to the fight against MDR pathogens and may even worsen the burden of adverse events from such interventions.

The effect of varying multidrug-resistence (MDR) definitions on rates of MDR gram-negative rods

Background

A multitude of definitions determining multidrug resistance (MDR) of Gram-negative organisms exist worldwide. The definitions differ depending on their purpose and on the issueing country or organization. The MDR definitions of the European Centre for Disease Prevention and Control (ECDC) were primarily chosen to harmonize epidemiological surveillance. The German Commission of Hospital Hygiene and Infection Prevention (KRINKO) issued a national guideline which is mainly used to guide infection prevention and control (IPC) measures. The Swiss University Hospital Zurich (UHZ) – in absentia of national guidelines – developed its own definition for IPC purposes. In this study we aimed to determine the effects of different definitions of multidrug-resistance on rates of Gram-negative multidrug-resistant organisms (GN-MDRO).

Methods

MDR definitions of the ECDC, the German KRINKO and the Swiss University Hospital Zurich were applied on a dataset comprising isolates of Escherichia coli, Klebsiella pneumoniae, Enterobacter sp., Pseudomonas aeruginosa, and Acinetobacter baumannii complex. Rates of GN-MDRO were compared and the percentage of patients with a GN-MDRO was calculated.

Results

In total 11′407 isolates from a 35 month period were included. For Enterobacterales and P. aeruginosa, highest MDR-rates resulted from applying the ‘ECDC-MDR’ definition. ‘ECDC-MDR’ rates were up to four times higher compared to ‘KRINKO-3/4MRGN’ rates, and up to six times higher compared to UHZ rates. Lowest rates were observed when applying the ‘KRINKO-4MRGN’ definitions. Comparing the ‘KRINKO-3/4MRGN’ with the UHZ definitions did not show uniform trends, but yielded higher rates for E. coli and lower rates for P. aeruginosa. On the patient level, the percentages of GN-MDRO carriers were 2.1, 5.5, 6.6, and 18.2% when applying the ‘KRINKO-4MRGN’, ‘UHZ-MDR’, ‘KRINKO-3/4MRGN’, and the ‘ECDC-MDR’ definition, respectively.

Conclusions

Different MDR-definitions lead to considerable variation in rates of GN-MDRO. Differences arise from the number of antibiotic categories required to be resistant, the categories and drugs considered relevant, and the antibiotic panel tested. MDR definitions should be chosen carefully depending on their purpose and local resistance rates, as definitions guiding isolation precautions have direct effects on costs and patient care.

Diagnostic Bacteriology in District Hospitals in Sub-Saharan Africa: At the Forefront of the Containment of Antimicrobial Resistance

This review provides an update on the factors fuelling antimicrobial resistance and shows the impact of these factors in low-resource settings. We detail the challenges and barriers to integrating clinical bacteriology in hospitals in low-resource settings, as well as the opportunities provided by the recent capacity building efforts of national laboratory networks focused on vertical single-disease programmes. The programmes for HIV, tuberculosis and malaria have considerably improved laboratory medicine in Sub-Saharan Africa, paving the way for clinical bacteriology. Furthermore, special attention is paid to topics that are less familiar to the general medical community, such as the crucial role of regulatory frameworks for diagnostics and the educational profile required for a productive laboratory workforce in low-resource settings. Traditionally, clinical bacteriology laboratories have been a part of higher levels of care, and, as a result, they were poorly linked to clinical practices and thus underused. By establishing and consolidating clinical bacteriology laboratories at the hospital referral level in low-resource settings, routine patient care data can be collected for surveillance, antibiotic stewardship and infection prevention and control. Together, these activities form a synergistic tripartite effort at the frontline of the emergence and spread of multi-drug resistant bacteria. If challenges related to staff, funding, scale, and the specific nature of clinical bacteriology are prioritized, a major leap forward in the containment of antimicrobial resistance can be achieved. The mobilization of resources coordinated by national laboratory plans and interventions tailored by a good understanding of the hospital microcosm will be crucial to success, and further contributions will be made by market interventions and business models for diagnostic laboratories. The future clinical bacteriology laboratory in a low-resource setting will not be an "entry-level version" of its counterparts in high-resource settings, but a purpose-built, well-conceived, cost-effective and efficient diagnostic facility at the forefront of antimicrobial resistance containment.

Antibiograms Cannot Be Used Interchangeably Between Acute Care Medical Centers and Affiliated Nursing Homes

OBJECTIVE

To determine whether antibiograms for Veterans Affairs (VA) nursing homes (NHs), termed Community Living Centers, are similar to those from their affiliated acute care medical centers.

DESIGN

Descriptive study.

SETTING AND PARTICIPANTS

We compared the 2017 antibiograms for VA NHs to their affiliated VA medical centers (VAMCs). Antibiograms included antibiotic susceptibility rates for commonly observed bacteria in this setting (Staphylococcus aureus, Enterococcus spp, Escherichia coli, Klebsiella spp, Proteus mirabilis, and Pseudomonas aeruginosa).

METHODS

Antibiograms were considered to be in complete agreement when the overall susceptibility rate between the NH and affiliated VAMC was either at or above 80% or below 80% across all bacteria and antibiotics. Average percentage of bacteria-antibiotic comparisons in disagreement per facility pair, and number of facilities with agreement for specific bacteria-antibiotic comparisons were also assessed. The chi-square test was used to compare disagreement between NH-VAMC facilities based on geographic proximity of the NH to the VAMC, culture source, and bed size.

RESULTS

A total of 119 NH-VAMC affiliate pairs were included in this analysis, with 71% (84/119) on the same campus and 29% (35/119) on geographically distinct campuses. None of the NH-VAMC pairs demonstrated complete agreement (all bacteria vs all antibiotics) between their antibiograms. On average, 20% of the bacteria-antibiotic comparisons from the antibiogram disagreed clinically per NH-VAMC pair, and almost twice as often the nursing home had lower susceptibility (higher resistance) than the acute care facility. Some bacteria-antibiotic comparisons agreed in all facilities (eg, E coli-imipenem; S aureus-linezolid; S aureus-vancomycin), while others showed greater disagreement (eg, Klebsiella spp-cefazolin; Klebsiella spp-ampicillin-sulbactam; P aeruginosa-ciprofloxacin). Rates of clinical disagreement were similar by geographic proximity of the NH to the VAMC, culture source, and bed size.

CONCLUSIONS AND IMPLICATIONS

Overall, this study showed a moderate lack of agreement between VA NH antibiograms and their affiliate VAMC antibiograms. Our data suggest that antibiograms of acute care facilities are often not accurate approximations of the nursing home resistance patterns and therefore should be used with caution (if at all) in guiding empiric antibiotic therapy.

Carbapenem-Nonsusceptible Pseudomonas aeruginosa Isolates from Intensive Care Units in the United States: a Potential Role for New β-Lactam Combination Agents

Pseudomonas aeruginosa, a frequent pathogen in the intensive care unit (ICU), has the propensity to develop antibiotic resistance. In particular, carbapenem-nonsusceptible (NS) P. aeruginosa poses tremendous challenges, and new antibiotics will be needed to treat this phenotype. Here we determine carbapenem nonsusceptibility rates for contemporary P. aeruginosa isolates from U.S. ICUs and in vitro activities of new β-lactam combination agents. Between July 2017 and June 2018, consecutive nonduplicate P. aeruginosa isolates from blood and respiratory tract sources were recovered from patients admitted to the ICUs of 36 geographically diverse U.S. hospitals. Antimicrobial susceptibility to the following antipseudomonal agents was tested: ceftazidime, imipenem, meropenem, ceftazidime-avibactam, and imipenem-relebactam (an investigational β-lactam/β-lactamase inhibitor). MICs and susceptibility rates were measured using Clinical and Laboratory Standards Institute reference broth microdilution methodology. Among the 538 consecutive ICU P. aeruginosa isolates collected, carbapenem nonsusceptibility was observed for 35% of the isolates and was more common among respiratory tract versus bloodstream specimens. Susceptibility rates, MIC₅₀ values, and MIC₉₀ values were as follows: ceftazidime-avibactam, 92.8%, 2 μg/ml, and 8 μg/ml; imipenem-relebactam, 91.5%, 0.25 μg/ml, and 2 μg/ml; ceftazidime, 77.1%, 4 μg/ml, and 64 μg/ml; meropenem, 72.7%, 1 μg/ml, and 16 μg/ml; imipenem, 67.1%, 2 μg/ml, and 16 μg/ml. Most (>75%) of the carbapenem-NS isolates were susceptible to ceftazidime-avibactam and imipenem-relebactam. In these U.S. hospital ICUs, carbapenem-NS P. aeruginosa isolates from respiratory sources were frequently observed. Novel β-lactam combination agents appear to retain active in vitro susceptibility profiles against these isolates and may play a role in the treatment of infections caused by carbapenem-NS P. aeruginosa strains.

Antibiotic Susceptibility of Bloodstream Isolates in a Pediatric Oncology Population: The Case for Ongoing Unit-specific Surveillance

Fever in a neutropenic oncology patient requires rapid initiation of effective empiric antibiotics to prevent mortality. We evaluated the appropriateness of our current empiric antibiotic regimen by assessing local antibiotic-susceptibility patterns in our pediatric oncology patients, and comparing them to the general pediatric patterns in our hospital. All blood culture isolates from pediatric oncology patients were reviewed over a 3-year period. Gram-negative and Gram-positive organisms were reviewed separately, with antibiotic susceptibilities for all unique isolates evaluated, and antibiograms generated and compared with general pediatric patients via the Fisher exact test. A total of 84% of Gram negatives were susceptible to meropenem; all resistant organisms were Pseudomonas aeruginosa, with 50% meropenem susceptibility. A total of 91% of Gram negatives were susceptible to cefepime, including 90% of P. aeruginosa and 80% of Escherichia coli. In total, 96% of Gram positives were vancomycin-susceptible; the only resistant organism was a single enterococcal isolate. In comparison with the general pediatric population, significantly fewer pseudomonal isolates were sensitive to meropenem among the oncology population (50% vs. 89%, P=0.0034). As such, in our population, meropenem does not provide adequate monotherapy against Pseudomonas. Ongoing surveillance of antibiotic resistance in this high-risk population is warranted, to ensure appropriate empiric antibiotic usage.

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.

Design and Implementation of a Visual Analytics Electronic Antibiogram within an Electronic Health Record System at a Tertiary Pediatric Hospital

BACKGROUND

Hospitals use antibiograms to guide optimal empiric antibiotic therapy, reduce inappropriate antibiotic usage, and identify areas requiring intervention by antimicrobial stewardship programs. Creating a hospital antibiogram is a time-consuming manual process that is typically performed annually.

OBJECTIVE

We aimed to apply visual analytics software to electronic health record (EHR) data to build an automated, electronic antibiogram ("e-antibiogram") that adheres to national guidelines and contains filters for patient characteristics, thereby providing access to detailed, clinically relevant, and up-to-date antibiotic susceptibility data.

METHODS

We used visual analytics software to develop a secure, EHR-linked, condition- and patient-specific e-antibiogram that supplies susceptibility maps for organisms and antibiotics in a comprehensive report that is updated on a monthly basis. Antimicrobial susceptibility data were grouped into nine clinical scenarios according to the specimen source, hospital unit, and infection type. We implemented the e-antibiogram within the EHR system at Children's Hospital of Philadelphia, a tertiary pediatric hospital and analyzed e-antibiogram access sessions from March 2016 to March 2017.

RESULTS

The e-antibiogram was implemented in the EHR with over 6,000 inpatient, 4,500 outpatient, and 3,900 emergency department isolates. The e-antibiogram provides access to rolling 12-month pathogen and susceptibility data that is updated on a monthly basis. E-antibiogram access sessions increased from an average of 261 sessions per month during the first 3 months of the study to 345 sessions per month during the final 3 months.

CONCLUSION

An e-antibiogram that was built and is updated using EHR data and adheres to national guidelines is a feasible replacement for an annual, static, manually compiled antibiogram. Future research will examine the impact of the e-antibiogram on antibiotic prescribing patterns.

Characterizing non-linear effects of hospitalisation duration on antimicrobial resistance in respiratory isolates: an analysis of a prospective nationwide surveillance system

OBJECTIVES

Our objective was to systematically study the influence of length of hospital stay on bacterial resistance in relevant respiratory tract isolates.

METHODS

Using prospective epidemiological data from the National Swiss Antibiotic Resistance Surveillance System, susceptibility testing results for respiratory isolates retrospectively retrieved from patients hospitalised between 2008 and 2014 were compiled. Generalized additive models were used to illustrate resistance rates relative to hospitalisation duration and to adjust for co-variables.

RESULTS

In all, 19 622 isolates of six relevant and predominant species were included. Resistance patterns for the predominant species showed a species-specific and antibiotic-resistance-specific profile in function of hospitalisation duration. The oxacillin resistance profile in Staphylococcus aureus isolates was constantly increasing (monophasic). The pattern of resistance to cefepime in Pseudomonas aeruginosa was biphasic with a decreasing resistance rate for the first 5 days of hospitalisation and an increase for days 6-30. A different biphasic pattern occurred in Escherichia coli regarding amoxicillin-clavulanic acid resistance: odds/day increased for the first 7 days of hospitalisation and then remained stable for days 8-30. In the adjusted models epidemiological characteristics such as age, ward type, hospital type and linguistic region were identified as relevant co-variables for the resistance rates. The contribution of these confounders was specific to the individual species/antibiotic resistance models.

CONCLUSIONS

Resistance rates do not follow a dichotomic pattern (early versus late nosocomial) as suggested by current hospital-acquired pneumonia treatment guidelines. Duration of hospitalisation rather appears to have a more complex and non-linear relationship with bacterial resistance in hospital-acquired pneumonia, also depending on host and environmental factors.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

BACKGROUND

Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.

METHODS

Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.

RESULTS

This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.

SUMMARY

The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.

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.

Implementing an Antibiotic Stewardship Program: Guidelines by the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America

Evidence-based guidelines for implementation and measurement of antibiotic stewardship interventions in inpatient populations including long-term care were prepared by a multidisciplinary expert panel of the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America. The panel included clinicians and investigators representing internal medicine, emergency medicine, microbiology, critical care, surgery, epidemiology, pharmacy, and adult and pediatric infectious diseases specialties. These recommendations address the best approaches for antibiotic stewardship programs to influence the optimal use of antibiotics.

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.

Antibiograms in resource limited settings: Are stratified antibiograms better?

Background Antibiograms often act as a reference guide for empirical selection of antibiotics. Hospital-wide antibiograms constructed on the basis of cumulative antimicrobial susceptibility data from diverse patient groups can often be misleading. In order to show the significance of age- and location-stratified antibiograms, this study compared hospital-wide antibiograms with stratified antibiograms for the clinical isolates of Pseudomonas aeruginosa. Methods Stratified antibiograms were created on the basis of patient age (<18 years, 18-50 years, >50 years) and location (inpatient or outpatient) using all 2011, 2012 and 2013 clinical isolates of P. aeruginosa isolates. Susceptibility rates were compared among cumulative and stratified antibiograms using non-parametric inferential statistics. Results The hospital-wide antibiogram under-estimated susceptibility rates in adult patients isolates (age group = 18-50 years) and over-estimated susceptibility rates in isolates from the paediatric patients and elderly. Paediatric isolates were found to be less susceptible to amikacin and imipenem, whereas isolates from elderly patients >50 years were less susceptible to ciprofloxacin. Statistically significant difference was seen in the susceptibility rates of OPD and IPD isolates of P. aeruginosa in the case of the paediatric age group. Susceptibility rates for all drugs were lower for isolates from inpatients than from outpatients. Conclusion Age and location associated differences in susceptibility rates have the potential to influence empirical antibiotic selection, which was shown in stratified antibiograms of P. aeruginosa that is obscured by hospital-wide antibiograms.

Selecting appropriate empirical antibiotic regimens for paediatric bloodstream infections: application of a Bayesian decision model to local and pooled antimicrobial resistance surveillance data

OBJECTIVES

The objective of this study was to evaluate the ability of weighted-incidence syndromic combination antibiograms (WISCAs) to inform the selection of empirical antibiotic regimens for suspected paediatric bloodstream infections (BSIs) by comparing WISCAs derived using data from single hospitals and from a multicentre surveillance dataset.

METHODS

WISCAs were developed by estimating the coverage of five empirical antibiotic regimens for childhood BSI using a Bayesian decision tree. The study used microbiological data on ∼2000 bloodstream isolates collected over 2 years from 19 European hospitals. We evaluated the ability of a WISCA to show differences in regimen coverage at two exemplar hospitals. For each, a WISCA was first calculated using only their local data; a second WISCA was calculated using pooled data from all 19 hospitals.

RESULTS

The estimated coverage of the five regimens was 72%-86% for Hospital 1 and 79%-94% for Hospital 2, based on their own data. In both cases, the best regimens could not be definitively identified because the differences in coverage were not statistically significant. For Hospital 1, coverage estimates derived using pooled data gave sufficient precision to reveal clinically important differences among regimens, including high coverage provided by a narrow-spectrum antibiotic combination. For Hospital 2, the hospital and pooled data showed signs of heterogeneity and the use of pooled data was judged not to be appropriate.

CONCLUSIONS

The Bayesian WISCA provides a useful approach to pooling information from different sources to guide empirical therapy and could increase confidence in the selection of narrow-spectrum regimens.

Comparison of Antibiotic Susceptibility Patterns of Bacterial Isolates Based on Time From Hospitalization and Culture Source: Implications for Hospital Antibiograms

We assessed the effects of time from hospitalization and culture source on bacterial susceptibility profiles. Increasing resistance correlated with increasing time from hospitalization for all bacterial groups, with 7 days in hospital representing the best time point for dichotomizing susceptibility rates rather than 48 hours. Antibiograms based on isolates from any source best represented susceptibility profiles.

Antibiotic Resistance Prevalence in Routine Bloodstream Isolates from Children's Hospitals Varies Substantially from Adult Surveillance Data in Europe

BACKGROUND

Surveillance of antimicrobial resistance (AMR) is central for defining appropriate strategies to deal with changing AMR levels. It is unclear whether childhood AMR patterns differ from those detected in isolates from adult patients.

METHODS

Resistance percentages of nonduplicate Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa bloodstream isolates from children less than 18 years of age reported to the Antibiotic Resistance and Prescribing in European Children (ARPEC) project were compared with all-age resistance percentages reported by the European Antimicrobial Resistance Surveillance Network (EARS-Net) for the same pathogen-antibiotic class combinations, period and countries. In addition, resistance percentages were compared between ARPEC isolates from children less than 1 year of age and children greater than or equal to1 year of age.

RESULTS

Resistance percentages for many important pathogen-antibiotic class combinations were different for ARPEC isolates compared with EARS-Net. E. coli and K. pneumoniae fluoroquinolone resistance percentages were substantially lower in ARPEC (13.4% and 17.9%) than in EARS-Net (23.0% and 30.7%), whereas the reverse was true for all pathogen-antibiotic class combinations in P. aeruginosa (for example, 27.3% aminoglycoside resistance in ARPEC, 19.3% in EARS-Net, 32.8% carbapenem resistance in ARPEC and 20.5% in EARS-Net), and for S. pneumoniae and macrolide resistance. For many Gram-negative pathogen-antibiotic class combinations, isolates from children greater than or equal to 1 year of age showed higher resistance percentages than isolates from children less than 1 year of age.

CONCLUSIONS

Age-stratified presentation of resistance percentage estimates by surveillance programs will allow identification of important variations in resistance patterns between different patient groups for targeted intervention.

[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.

Factors associated with methicillin-resistant coagulase-negative staphylococci as causing organisms in deep sternal wound infections after cardiac surgery

Established preoperative antibiotic prophylaxis in cardiac surgery is ineffective against methicillin-resistant coagulase-negative staphylococci (CoNS). This case-control study aimed to determine factors predicting deep sternal wound infections due to methicillin-resistant CoNS. All cardiac surgery patients undergoing sternotomy between June 2009 and March 2013 prospectively documented in a Swiss tertiary care center were included. Among 1999 patients, 82 (4.1%) developed deep sternal wound infection. CoNS were causal in 36 (44%) patients, with 25/36 (69%) being methicillin resistant. Early reintervention for noninfectious causes (odds ratio (OR) 4.3; 95% confidence interval (CI) 1.9-9.5) was associated with methicillin-resistant CoNS deep sternal wound infection. Among CoNS deep sternal wound infection, perioperative antimicrobial therapy (p 0.002), early reintervention for noninfectious causes (OR 7.9; 95% CI 0.9-71.1) and time between surgery and diagnosis of infection over 21 days (OR 10.8; 95% CI 1.2-97.8) were associated with methicillin resistance. These findings may help to better tailor preoperative antimicrobial prophylaxis.

Variation in antibiotic susceptibility of uropathogens by age among ambulatory pediatric patients

We compared uropathogen antibiotic susceptibility across age groups of ambulatory pediatric patients. For Escherichia coli (n=5,099) and other Gram-negative rods (n=626), significant differences (p<0.05) existed across age groups for ampicillin, cefazolin, and trimethoprim/sulfamethoxazole susceptibility. In E. coli, differences in trimethoprim/sulfamethoxazole susceptibility varied from 79% in children under 2 to 88% in ages 16-18 (p<0.001), while ampicillin susceptibility varied from 30% in children under 2 to 53% in ages 2-5 (p=0.015). Uropathogen susceptibility to common urinary anti-infectives may be lower in the youngest children. Further investigation into these differences is needed to facilitate appropriate and prudent treatment of urinary tract infections.

Change of antibiotic susceptibility testing guidelines from CLSI to EUCAST: influence on cumulative hospital antibiograms

OBJECTIVE

We studied whether the change in antibiotic susceptibility testing (AST) guidelines from CLSI to EUCAST influenced cumulative antibiograms in a tertiary care hospital in Switzerland.

METHODS

Antibiotic susceptibilities of non-duplicate isolates collected within a one-year period before (period A) and after (period B) changing AST interpretation from CLSI 2009 to EUCAST 1.3 (2011) guidelines were analysed. In addition, period B isolates were reinterpreted according to the CLSI 2009, CLSI 2013 and EUCAST 3.1 (2013) guidelines.

RESULTS

The majority of species/drug combinations showed no differences in susceptibility rates comparing periods A and B. However, in some gram-negative bacilli, decreased susceptibility rates were observed when comparing CLSI 2009 with EUCAST 1.3 within period B: Escherichia coli / cefepime, 95.8% (CLSI 2009) vs. 93.1% (EUCAST 1.3), P=0.005; Enterobacter cloacae / cefepime, 97.0 (CLSI 2009) vs. 90.5% (EUCAST 1.3), P=0.012; Pseudomonas aeruginosa / meropenem, 88.1% (CLSI 2009) vs. 78.3% (EUCAST 1.3), P=0.002. These differences were still evident when comparing susceptibility rates according to the CLSI 2013 guideline with EUCAST 3.1 guideline. For P. aeruginosa and imipenem, a trend towards a lower antibiotic susceptibility rate in ICUs compared to general wards turned into a significant difference after the change to EUCAST: 87.9% vs. 79.8%, P=0.08 (CLSI 2009) and 86.3% vs. 76.8%, P=0.048 (EUCAST 1.3).

CONCLUSIONS

The change of AST guidelines from CLSI to EUCAST led to a clinically relevant decrease of susceptibility rates in cumulative antibiograms for defined species/drug combinations, particularly in those with considerable differences in clinical susceptibility breakpoints between the two guidelines.

Influence of clinical breakpoint changes from CLSI 2009 to EUCAST 2011 antimicrobial susceptibility testing guidelines on multidrug resistance rates of Gram-negative rods

Multidrug resistance (MDR) rates of Gram-negative rods were analyzed comparing CLSI 2009 and EUCAST 2011 antibiotic susceptibility testing guidelines. After EUCAST 2011 was applied, the MDR rates increased for Klebsiella pneumoniae (2.2%), Enterobacter cloacae (1.1%), Pseudomonas aeruginosa (0.7%), and Escherichia coli (0.4%). A total of 24% of Enterobacteriaceae MDR isolates and 12% of P. aeruginosa MDR isolates were categorized as MDR due to breakpoint changes.

Comparison of hospital-wide and age and location - stratified antibiograms of S. aureus, E. coli, and S. pneumoniae: age- and location-stratified antibiograms

Background

Antibiograms created by aggregating hospital-wide susceptibility data from diverse patients can be misleading. To demonstrate the utility of age- and location-stratified antibiograms, we compared stratified antibiograms for three common bacterial pathogens, E. coli, S. aureus, and S. pneumoniae. We created stratified antibiograms based on patient age (<18 years, 18–64 years, >/=65 years), and inpatient or outpatient location using all 2009 E. coli and S. aureus, and all 2008–2009 S. pneumoniae isolates submitted to our clinical microbiology laboratory. We compared susceptibility rates among cumulative and stratified antibiograms using descriptive statistics.

Findings

For E. coli and S. aureus, the institution-wide antibiogram overestimated resistance in pediatic isolates and underestimated resistance in isolates from the elderly. For E. coli, pediatric isolates were less susceptible to ampicillin and ampicillin-sulbactam and more susceptible to gentamicin and ciprofloxacin compared to adult isolates (p < 0.05 for all), and isolates from patients >65 years were least susceptible to ciprofloxacin (71%). For S. aureus, susceptibility to oxacillin, clindamycin, and levofloxacin was highest among children and decreased with increasing age (p < .001 for all). For S. pneumoniae, pediatric isolates were less susceptible than adult isolates to all agents except penicillin (IV breakpoint). Within children there were significant differences in susceptibility of inpatient and outpatient isolates of E. coli but not of S. aureus or S. pneumoniae.

Conclusions

Stratified antibiograms reveal age - associated differences in susceptibility of E. coli, S. aureus, and S. pneumoniae that are obscured by hospital-wide antibiograms. Age-stratified antibiograms have potential to influence antibiotic selection.

Resistance surveillance studies: a multifaceted problem--the fluoroquinolone example

INTRODUCTION

This review summarizes data on the fluoroquinolone resistance epidemiology published in the previous 5 years.

MATERIALS AND METHODS

The data reviewed are stratified according to the different prescription patterns by either primary- or tertiary-care givers and by indication. Global surveillance studies demonstrate that fluoroquinolone- resistance rates increased in the past several years in almost all bacterial species except Staphylococcus pneumoniae and Haemophilus influenzae causing community-acquired respiratory tract infections (CARTIs), as well as Enterobacteriaceae causing community-acquired urinary tract infections. Geographically and quantitatively varying fluoroquinolone resistance rates were recorded among Gram-positive and Gram-negative pathogens causing healthcare-associated respiratory tract infections. One- to two-thirds of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) were fluoroquinolone resistant too, thus, limiting the fluoroquinolone use in the treatment of community- as well as healthcare-acquired urinary tract and intra-abdominal infections. The remaining ESBL-producing or plasmid-mediated quinolone resistance mechanisms harboring Enterobacteriaceae were low-level quinolone resistant. Furthermore, 10-30 % of H. influenzae and S. pneumoniae causing CARTIs harbored first-step quinolone resistance determining region (QRDR) mutations. These mutants pass susceptibility testing unnoticed and are primed to acquire high-level fluoroquinolone resistance rapidly, thus, putting the patient at risk. The continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some current guidelines for the treatment of intra-abdominal infections or even precludes the use of fluoroquinolones in certain indications like gonorrhea and pelvic inflammatory diseases in those geographic areas in which fluoroquinolone resistance rates and/or ESBL production is high. Fluoroquinolone resistance has been selected among the commensal flora colonizing the gut, nose, oropharynx, and skin, so that horizontal gene transfer between the commensal flora and the offending pathogen as well as inter- and intraspecies recombinations contribute to the emergence and spread of fluoroquinolone resistance among pathogenic streptococci. Although interspecies recombinations are not yet the major cause for the emergence of fluoroquinolone resistance, its existence indicates that a large reservoir of fluoroquinolone resistance exists. Thus, a scenario resembling that of a worldwide spread of β-lactam resistance in pneumococci is conceivable. However, many resistance surveillance studies suffer from inaccuracies like the sampling of a selected patient population, restricted geographical sampling, and undefined requirements of the user, so that the results are biased. The number of national centers is most often limited with one to two participating laboratories, so that such studies are point prevalence but not surveillance studies. Selected samples are analyzed predominantly as either hospitalized patients or patients at risk or those in whom therapy failed are sampled; however, fluoroquinolones are most frequently prescribed by the general practitioner. Selected sampling results in a significant over-estimation of fluoroquinolone resistance in outpatients. Furthermore, the requirements of the users are often not met; the prescribing physician, the microbiologist, the infection control specialist, public health and regulatory authorities, and the pharmaceutical industry have diverse interests, which, however, are not addressed by different designs of a surveillance study. Tools should be developed to provide customer-specific datasets.

CONCLUSION

Consequently, most surveillance studies suffer from well recognized but uncorrected biases or inaccuracies. Nevertheless, they provide important information that allows the identification of trends in pathogen incidence and antimicrobial resistance.

Different patterns of inappropriate antimicrobial use in surgical and medical units at a tertiary care hospital in Switzerland: a prevalence survey

Background

Unnecessary or inappropriate use of antimicrobials is associated with the emergence of antimicrobial resistance, drug toxicity, increased morbidity and health care costs. Antimicrobial use has been reported to be incorrect or not indicated in 9–64% of inpatients. We studied the quality of antimicrobial therapy and prophylaxis in hospitalized patients at a tertiary care hospital to plan interventions to improve the quality of antimicrobial prescription.

Methodology/Principal Findings

Experienced infectious diseases (ID) fellows performed audits of antimicrobial use at regular intervals among all patients—with or without antimicrobials—hospitalized in predefined surgical, medical, haemato-oncological, or intensive care units. Data were collected from medical and nursing patient charts with a standardized questionnaire. Appropriateness of antimicrobial use was evaluated using a modified algorithm developed by Gyssens et al.; the assessment was double-checked by a senior ID specialist.

We evaluated 1577 patients of whom 700 (44.4%) had antimicrobials, receiving a total of 1270 prescriptions. 958 (75.4%) prescriptions were for therapy and 312 (24.6%) for prophylaxis. 37.0% of therapeutic and 16.6% of prophylactic prescriptions were found to be inappropriate. Most frequent characteristics of inappropriate treatments included: No indication (17.5%); incorrect choice of antimicrobials (7.6%); incorrect application of drugs (9.3%); and divergence from institutional guidelines (8%). Characteristics of inappropriate prophylaxes were: No indication (9%); incorrect choice of antimicrobials (1%); duration too long or other inappropriate use (6.7%). Patterns of inappropriate antimicrobial varied widely in the different hospital units; empirical prescriptions were more frequently incorrect than prescriptions based on available microbiological results.

Conclusions/Significance

Audits of individual patient care provide important data to identify local problems in antimicrobial prescription practice. In our study, antimicrobial prescriptions without indication, and divergence from institutional guidelines were frequent errors. Based on these results, we will tailor education, amend institutional guidelines and further develop the infectious diseases consultation service.