The Cost-Effectiveness of Rapid Diagnostic Testing for the Diagnosis of Bloodstream Infections with or without Antimicrobial Stewardship

Impact of an Antimicrobial Stewardship Bundle for Uncomplicated Gram-Negative Bacteremia

BACKGROUND

Recent studies in gram-negative bacteremia (GNB) suggest that intravenous (IV) to oral (PO) switch and short treatment durations yield similar clinical outcomes and fewer adverse events. Antimicrobial stewardship program (ASP) bundled initiatives have been associated with improved clinical outcomes for bloodstream infections.

METHODS

This single-center retrospective cohort evaluation included inpatient adults from 11/2014-10/2015 and 10/2017-9/2018 with GNB. The pre-ASP period was before the establishment of an ASP program. In the post period, the ASP promoted IV-to-PO switches, avoidance of repeat blood cultures, and short treatment durations for patients with uncomplicated GNB. The primary outcome was duration of antibiotic therapy. Secondary outcomes included process measures associated with the bundle and clinical outcomes.

RESULTS

One hundred thirty-seven patients met criteria for inclusion, with 51 patients in the pre group and 86 patients in the post group. Background characteristics were similar between groups. The median duration of therapy (interquartile range) was 14 (10-16) days in the pre group and 10 days (7-14) in the post group (P < .001). The median day of IV-to-PO switch was day 5 (4-6) in the pre group vs day 4 (3-5) in the post group (P = .046). The average total hospital cost per case decreased by 27% in the post group (P = .19). Mortality rates and bacteremia recurrence were not significantly different between groups.

CONCLUSIONS

An ASP bundle for uncomplicated GNB was associated with reduced durations of therapy and earlier PO switch. These findings highlight the synergistic role of ASPs in optimizing antibiotic use and promoting patient safety.

The Impact of Integrating Rapid PCR-Based Blood Culture Identification Panel to an Established Antimicrobial Stewardship Program in the United Arab of Emirates

BACKGROUND

Studies have shown improvement in the outcome of blood stream infections (BSI) due to the use of Rapid PCR-Based Blood Culture Identification Panel (BCID) in Antimicrobial stewardship programs (ASP). There is currently no data on the use of BCID with ASP in the United Arab Emirates (UAE).

METHOD

Pre-post quasiexperimental study included hospitalized patients with BSI, their positive blood cultures on BCID were studied in 2 groups: conventional culture with ASP (AS), and BCID with ASP (BCID). The primary outcomes were time to first appropriate antimicrobial therapy, infection related length of stay (LOS), ICU admission, 14 days bacteremia recurrence and in-hospital mortality. Secondary outcomes were 30 days reinfection rate, hospital cost and ASP interventions.

RESULTS

Out of total 477 positive blood cultures, 206 (AS and BCID) with real BSI were included. The time needed for organism identification was shorter in the BCID group than in the AS group (1.3 h vs. 51 h; P = 0.0002). BCID had a shorter time to appropriate antimicrobial therapy than AS (17.8 h vs.45 h; P = 0.0004). No statistical difference was observed in mortality rate, 14 days bacteremia recurrence, ICU admission, hospital cost, LOS or ASP interventions.

CONCLUSION

Implementing BCID to ASP significantly decreased the time needed to identify the organism and time to appropriate antimicrobial therapy. Similarly, LOS and hospital cost were reduced, however, the reduction was not statistically significant.

Accurate Detection of the Four Most Prevalent Carbapenemases in E. coli and K. pneumoniae by High-Resolution Mass Spectrometry

Background

At present, phenotypic growth inhibition techniques are used in routine diagnostic microbiology to determine antimicrobial resistance of bacteria. Molecular techniques such as PCR are often used for confirmation but are indirect as they detect particular resistance genes. A direct technique would be able to detect the proteins of the resistance mechanism itself. In the present study targeted high resolution mass spectrometry assay was developed for the simultaneous detection of KPC, OXA-48-like, NDM, and VIM carbapenemases.

Methods

Carbapenemase specific target peptides were defined by comparing available sequences in GenBank. Selected peptide sequences were validated using 62 Klebsiella pneumoniae and Escherichia coli isolates containing: 16 KPC, 21 OXA-48-like, 16 NDM, 13 VIM genes, and 21 carbapenemase negative isolates.

Results

For each carbapenemase, two candidate peptides were validated. Method validation was performed in a blinded manner for all 83 isolates. All carbapenemases were detected. The majority was detected by both target peptides. All target peptides were 100% specific in the tested isolates and no peptide carry-over was detected.

Conclusion

The applied targeted bottom-up mass spectrometry technique is able to accurately detect the four most prevalent carbapenemases in a single analysis.

MALDI-TOF Mass Spectrometry and Specific Biomarkers: Potential New Key for Swift Identification of Antimicrobial Resistance in Foodborne Pathogens

Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) is today the reference method for direct identification of microorganisms in diagnostic laboratories, as it is notably time- and cost-efficient. In the context of increasing cases of enteric diseases with emerging multi-drug resistance patterns, there is an urgent need to adopt an efficient workflow to characterize antimicrobial resistance (AMR). Current approaches, such as antibiograms, are time-consuming and directly impact the "patient-physician" workflow. Through this mini-review, we summarize how the detection of specific patterns by MALDI-TOF MS, as well as bioinformatics, become more and more essential in research, and how these approaches will help diagnostics in the future. Along the same lines, the idea to export more precise biomarker identification steps by MALDI-TOF(/TOF) MS data towards AMR identification pipelines is discussed. The study also critically points out that there is currently still a lack of research data and knowledge on different foodborne pathogens as well as several antibiotics families such as macrolides and quinolones, and many questions are still remaining. Finally, the innovative combination of whole-genome sequencing and MALDI-TOF MS could be soon the future for diagnosis of antimicrobial resistance in foodborne pathogens.

Development of a Multiplex PCR Platform for the Rapid Detection of Bacteria, Antibiotic Resistance, and Candida in Human Blood Samples

The diagnosis of bloodstream infections (BSIs) still relies on blood culture (BC), but low turnaround times may hinder the early initiation of an appropriate antimicrobial therapy, thus increasing the risk of infection-related death. We describe a direct and rapid multiplex PCR-based assay capable of detecting and identifying 16 bacterial and four Candida species, as well as three antibiotic-resistance determinants, in uncultured samples. Using whole-blood samples spiked with microorganisms at low densities, we found that the MicrobScan assay had a mean limit of detection of 15.1 ± 3.3 CFU of bacteria/Candida per ml of blood. When applied to positive BC samples, the assay allowed the sensitive and specific detection of BSI pathogens, including bla _KPC-, mecA-, or vanA/vanB-positive bacteria. We evaluated the assay using prospectively collected blood samples from patients with suspected BSI. The sensitivity and specificity were 86.4 and 97.0%, respectively, among patients with positive BCs for the microorganisms targeted by the assay or patients fulfilling the criteria for infection. The mean times to positive or negative assay results were 5.3 ± 0.2 and 5.1 ± 0.1 h, respectively. Fifteen of 20 patients with MicrobScan assay-positive/BC-negative samples were receiving antimicrobial therapy. In conclusion, the MicrobScan assay is well suited to complement current diagnostic methods for BSIs.

Antimicrobial stewardship in children: more shadows than lights?

Introduction: The aim of this review is to evaluate the effectiveness of antimicrobial stewardship (AMS) programmes in the pediatric population in improving clinical outcomes, altering prescribing behavior, controlling antimicrobial resistance and measuring the cost-effectiveness.Areas covered: Medline Ovid MEDLINE(R), Embase, and Cochrane Library were searched on 30 September 2018 combining MeSH and free terms for 'antimicrobial stewardship', 'clinical outcomes', 'antimicrobial resistance', 'cost-effectiveness' and 'prescribing behavior'. Several studies have been conducted on the impact of antimicrobial stewardship programmes (ASPs) in children, which showed a positive impact on length of hospital stay and days of therapy. Together with ASP bundles, the introduction of fast microbiology and point-of-care tests showed a positive impact in terms of rapid identification of the pathogen, time to optimal antimicrobial therapy and reduction of antibiotic use, without worsening clinical outcomes. These improvements turned out to be limited over time. Conflicting results were observed regarding the impact of ASPs on antimicrobial resistance and on cost-effectiveness and cost-benefits, due to the lack of homogeneity between studies.Expert opinion: Evidence regarding the impact of ASPs in children is limited to single center studies, with different study designs, making it impossible to draw unequivocal conclusions. High quality studies are needed. More feasable approaches should be designed both for inpatients and outpatients and for critical patients.

Rapid microbiological tests for bloodstream infections due to multidrug resistant Gram-negative bacteria: therapeutic implications

BACKGROUND

Treating severe infections due to multidrug-resistant Gram-negative bacteria (MDR-GNB) is one of the most important challenges for clinicians worldwide, partly because resistance may remain unrecognized until identification of the causative agent and/or antimicrobial susceptibility testing (AST). Recently, some novel rapid test for identification and/or AST of MDR-GNB from positive blood cultures or the blood of patients with bloodstream infections (BSIs) have become available.

OBJECTIVES

The objective of this narrative review is to discuss the advantages and limitations of different rapid tests for identification and/or AST of MDR-GNB from positive blood cultures or the blood of patients with BSI, as well as the available evidence on their possible role to improve therapeutic decisions and antimicrobial stewardship.

SOURCES

Inductive PubMed search for publications relevant to the topic.

CONTENT

The present review is structured in the following way: (a) rapid tests on positive blood cultures; (b) rapid tests directly on whole blood; (c) therapeutic implications.

IMPLICATIONS

Novel molecular and phenotypic rapid tests for identification and AST show the potential for favourably influencing patients' outcomes and results of antimicrobial stewardship interventions by reducing both the time to effective treatment and the misuse of antibiotics, although the interpretation about their impact on actual therapeutic decisions and patients' outcomes is still complex. Factors such as feasibility and personnel availability, as well as the detailed knowledge of the local microbiological epidemiology, need to be considered very carefully when implementing novel rapid tests in laboratory workflows and algorithms. Providing high-level, comparable evidence on the clinical impact of rapid identification and AST is becoming of paramount importance for MDR-GNB infections, since in the near future rapid identification of specific resistance mechanisms could be crucial for guiding rapid, effective, and targeted therapy against specific resistance mechanisms.

Clinical Utility of Advanced Microbiology Testing Tools

Advanced microbiology technologies are rapidly changing our ability to diagnose infections, improve patient care, and enhance clinical workflow. These tools are increasing the breadth, depth, and speed of diagnostic data generated per patient, and testing is being moved closer to the patient through rapid diagnostic technologies, including point-of-care (POC) technologies.

Advanced microbiology technologies are rapidly changing our ability to diagnose infections, improve patient care, and enhance clinical workflow. These tools are increasing the breadth, depth, and speed of diagnostic data generated per patient, and testing is being moved closer to the patient through rapid diagnostic technologies, including point-of-care (POC) technologies. While select stakeholders have an appreciation of the value/importance of improvements in the microbial diagnostic field, there remains a disconnect between clinicians and some payers and hospital administrators in terms of understanding the potential clinical utility of these novel technologies. Therefore, a key challenge for the clinical microbiology community is to clearly articulate the value proposition of these technologies to encourage payers to cover and hospitals to adopt advanced microbiology tests. Specific guidance on how to define and demonstrate clinical utility would be valuable. Addressing this challenge will require alignment on this topic, not just by microbiologists but also by primary care and emergency room (ER) physicians, infectious disease specialists, pharmacists, hospital administrators, and government entities with an interest in public health. In this article, we discuss how to best conduct clinical studies to demonstrate and communicate clinical utility to payers and to set reasonable expectations for what diagnostic manufacturers should be required to demonstrate to support reimbursement from commercial payers and utilization by hospital systems.

Challenges and research priorities to progress the impact of antimicrobial stewardship

Antimicrobial stewardship programmes have been playing an important role in patient care and hospital policies. These programmes are now recognised as formal strategies for curbing the upward trend in antibiotic resistance and for improving the appropriate antimicrobial and antifungal use. The role of such programs in the era of antimicrobial resistance presents several unique challenges and opportunities, most notably in the diagnostic and therapeutic setting. Controversies remain regarding the most effective interventions and the appropriate design to evaluate their impact. In this review, based on rounds of discussion, we explain the most important challenges faced by antibiotic stewardship and antifungal stewardship programmes. We also try to suggest areas for further research.

Centralized Communication of Blood Culture Results Leveraging Antimicrobial Stewardship and Rapid Diagnostics

Objective

This study aimed to determine if integrating antimicrobial stewardship program (ASP) personnel with rapid diagnostic testing resulted in improved outcomes for patients with positive blood cultures.

Method

Beginning in 2016, Saint Luke’s Health System (SLHS) implemented a new process where all positive blood cultures were communicated to ASP personnel or SLHS pharmacy staff. Pharmacists then became responsible for interpreting results, assessing patient specific information, and subsequently relaying culture and treatment information to providers. This was a multisite, pre-post, quasi-experimental study (Pre: August to December 2014; Post: August to December 2016). Patients 18 years of age and older with a positive blood culture during admission were included (2014, n = 218; 2016, n = 286). Coprimary outcomes of time to optimal and appropriate therapy were determined from time of culture positivity via gram stain. Secondary outcomes focused on clinical, process, and fiscal endpoints. A pre-post intervention physician survey was conducted to assess the impact on antimicrobial decision making and perceived effect on patient outcomes.

Results

There was no difference in time to appropriate therapy groups (P = .079). Time to optimal therapy was 9.2 hours shorter in 2016 (P = .004). Provider surveys indicated the process improved communication among clinicians and facilitated a shared decision-making process with a perceived improvement in patient care.

Conclusions

An ASP-led blood culture communication process for patients with positive blood cultures was shown to improve time to optimal therapy, support physicians in their decision making on critical lab data, and improve the care for hospitalized patients.

Evaluation of QuickFISH and maldi Sepsityper for identification of bacteria in bloodstream infection

BACKGROUND

Early detection of bacteria and their antibiotic susceptibility patterns are critical to guide therapeutic decision-making for optimal care of septic patients. The current gold standard, blood culturing followed by subculture on agar plates for subsequent identification, is too slow leading to excessive use of broad-spectrum antibiotic with harmful consequences for the patient and, in the long run, the public health. The aim of the present study was to assess the performance of two commercial assays, QuickFISH® (OpGen) and Maldi Sepsityper™ (Bruker Daltonics) for early and accurate identification of microorganisms directly from positive blood cultures.

MATERIALS AND METHODS

During two substudies of positive blood cultures, the two commercial assays were assessed against the routine method used at the clinical microbiology laboratory, Unilabs AB, at Skaraborg Hospital, Sweden.

RESULTS

The Maldi Sepsityper™ assay enabled earlier microorganism identification. Using the cut-off for definite species identification according to the reference method (>2.0), sufficiently accurate species identification was achieved, but only among Gram-negative bacteria. The QuickFISH^® assay was time-saving and showed high concordance with the reference method, 94.8% (95% CI 88.4-98.3), when the causative agent was covered by the QuickFISH^® assay.

CONCLUSIONS

The use of the commercial assays may shorten the time to identification of causative agents in bloodstream infections and can be a good complement to the current clinical routine diagnostics. Nevertheless, the performance of the commercial assays is considerably affected by the characteristics of the causative agents.

Evaluation of the ePlex Blood Culture Identification Panels for Detection of Pathogens in Bloodstream Infections

Rapid identification and susceptibility testing results are of importance for the early appropriate therapy of bloodstream infections. The ePlex (GenMark Diagnostics) blood culture identification (BCID) panels are fully automated PCR-based assays designed to identify Gram-positive and Gram-negative bacteria, fungi, and bacterial resistance genes within 1.5 h from positive blood culture.

Rapid identification and susceptibility testing results are of importance for the early appropriate therapy of bloodstream infections. The ePlex (GenMark Diagnostics) blood culture identification (BCID) panels are fully automated PCR-based assays designed to identify Gram-positive and Gram-negative bacteria, fungi, and bacterial resistance genes within 1.5 h from positive blood culture. Consecutive non-duplicate positive blood culture episodes were tested by the ePlex system prospectively. The choice of panel(s) (Gram-positive, Gram-negative, and/or fungal pathogens) was defined by Gram-stained microscopy of blood culture-positive bottles (BacT/Alert; bioMérieux). Results with the ePlex panels were compared to the identification results obtained by standard culture-based workflow. In total, 216 positive blood culture episodes were evaluable, yielding 263 identification results. The sensitivity/positive predictive value for detection by the ePlex panels of targeted cultured isolates were 97% and 99% for the Gram-positive panel and 99% and 96% for the Gram-negative panel, resulting in overall agreement rates of 96% and 94% for the Gram-positive and Gram-negative panel, respectively. All 26 samples with targeted resistance results were correctly detected by the ePlex panels. The ePlex panels provided highly accurate results and proved to be an excellent diagnostic tool for the rapid identification of pathogens causing bloodstream infections. The short time to results may be of added value for optimizing the clinical management of patients with sepsis.

Impact of infectious diseases consultation on the outcome of patients with bacteraemia

Bacteraemia or bloodstream infections (BSI) are associated with much morbidity and mortality. Management of patients with bacteraemia is complex, and the increase in immunosuppressed patients and multidrug-resistant organisms poses additional challenges. The objective of this review is to assess the available published information about the impact of different aspects of management on the outcome of patients with BSI, and, specifically, the importance of infectious diseases specialists (IDS) consultation. The impact of management by IDS on different aspects, including interpretation of newer rapid techniques, early evaluation and treatment, and follow up, are reviewed. Overall, the available data suggest that IDS intervention improves the management and outcome of patients with BSI, either through consultation or structured unsolicited interventions in the context of multidisciplinary bacteraemia programmes.

Is It Actionable? An Evaluation of the Rapid PCR-Based Blood Culture Identification Panel on the Management of Gram-Positive and Gram-Negative Blood Stream Infections

Background

There is growing interest in the use of rapid blood culture identification (BCID) in antimicrobial stewardship programs (ASPs). Although many studies have looked at its clinical and economic utility, its comparative utility in gram-positive and gram-negative blood stream infections (BSIs) has not been as well characterized.

Methods

The study was a quasi-experimental retrospective study at the Mayo Clinic in Phoenix, Arizona. All adult patients with positive blood cultures before BCID implementation (June 2015 to December 2015) and after BCID implementation (June 2016 to December 2016) were included. The outcomes of interest included time to first appropriate antibiotic escalation, time to first appropriate antibiotic de-escalation, time to organism identification, length of stay, infectious diseases consultation, discharge disposition, and in-hospital mortality.

Results

In total, 203 patients were included in this study. There was a significant difference in the time to organism identification between the pre- and post-BCID cohorts (27.1 hours vs 3.3 hours, P < .0001). BCID did not significantly reduce the time to first appropriate antimicrobial escalation or de-escalation for either gram-positive BSIs (GP-BSIs) or gram-negative BSIs (GN-BSIs). Providers were more likely to escalate antimicrobial therapy in GP-BSIs after gram stain and more likely to de-escalate therapy in GN-BSIs after susceptibilities. Although there were no significant differences in changes in antimicrobial therapy for organism identification by BCID vs traditional methods, more than one-quarter of providers (28.1%) made changes after organism identification. There were no differences in hospital length of stay or in-hospital mortality comparing pre- vs post-BCID.

Conclusions

Although BCID significantly reduced the time to identification for both GP-BSIs and GN-BSIs, BCID did not reduce the time to first appropriate antimicrobial escalation and de-escalation.

Advances in Rapid Molecular Blood Culture Diagnostics: Healthcare Impact, Laboratory Implications, and Multiplex Technologies

BACKGROUND

For far too long, the diagnosis of bloodstream infections has relied on time-consuming blood cultures coupled with traditional organism identification and susceptibility testing. Technologies to define the culprit in bloodstream infections have gained sophistication in recent years, notably by application of molecular methods.

CONTENT

In this review, we summarize the tests available to clinical laboratories for molecular rapid identification and resistance marker detection in blood culture bottles that have flagged positive. We explore the cost-benefit ratio of such assays, covering aspects that include performance characteristics, effect on patient care, and relevance to antibiotic stewardship initiatives.

SUMMARY

Rapid blood culture diagnostics represent an advance in the care of patients with bloodstream infections, particularly those infected with resistant organisms. These diagnostics are relatively easy to implement and appear to have a positive cost-benefit balance, particularly when fully incorporated into a hospital's antimicrobial stewardship program.

Interplay between Rapid Diagnostic Tests and Antimicrobial Stewardship Programs among Patients with Bloodstream and Other Severe Infections

BACKGROUND

Antimicrobial stewardship programs (ASPs) aim to provide optimal antimicrobial therapy to patients quickly to improve the likelihood of overcoming infection while reducing the risk of adverse effects. Rapid diagnostic tests (RDTs) for infectious diseases have become an integral tool for ASPs to achieve these aims.

CONTENT

This review explored the demonstrated clinical value of longer-standing technologies and implications of newer RDTs from an antimicrobial stewardship perspective. Based on available literature, the focus was on the use of RDTs in bloodstream infections (BSIs), particularly those that perform organism identification and genotypic resistance detection, phenotypic susceptibility testing, and direct specimen testing. Clinical implications of rapid testing among respiratory, central nervous system, and gastrointestinal infections are also reviewed.

SUMMARY

Coupling RDTs with ASPs facilitates the appropriate and timely use of test results, translating into improved patient outcomes through optimization of antimicrobial use. These benefits are best demonstrated in the use of RDT in BSIs. Rapid phenotypic susceptibility testing offers the potential for early pharmacokinetic/pharmacodynamic optimization, and direct specimen testing on blood may allow ASPs to initiate appropriate therapy and/or tailor empiric therapy even sooner than other RDTs. RDTs for respiratory, central nervous system, and gastrointestinal illnesses have also shown significant promise, although more outcome studies are needed to evaluate their full impact.

The Cost-Effectiveness of Corticosteroids for the Treatment of Community-Acquired Pneumonia

BACKGROUND

The use of corticosteroids as adjunct treatment for community-acquired pneumonia (CAP) is associated with potential clinical benefits. The aim of this study was to evaluate the cost-effectiveness of this approach.

METHODS

We constructed a decision-analytic model comparing the use of corticosteroids + antibiotics with that of placebo + antibiotics for the treatment of CAP. Cost-effectiveness was determined by calculating deaths averted and incremental cost-effectiveness ratios. Uncertainty was addressed by plotting cost-effectiveness planes and acceptability curves for various willingness-to-pay thresholds.

RESULTS

In the base-case analysis, corticosteroids + antibiotics resulted in savings of $142,795 per death averted. In the probabilistic analysis, at a willingness to pay of $50,000, corticosteroids + antibiotics had a 86.4% chance of being cost-effective compared with placebo + antibiotics. In cost-effectiveness acceptability curves, the corticosteroids + antibiotics strategy was cost-effective in 87.6% to 94.3% of simulations compared with the placebo + antibiotics strategy for a willingness to pay ranging from $0 to $50,000. In patients with severe CAP (Pneumonia Severity Index classes IV/V) the corticosteroids + antibiotics strategy resulted in savings of $70,587 and had a 82.6% chance of being cost-effective compared with the placebo + antibiotics strategy.

CONCLUSIONS

The use of corticosteroids + antibiotics is a cost-effective strategy and results in considerable health care cost-savings, especially among patients with severe CAP (Pneumonia Severity Index classes IV/V).

Rapid antibiotic susceptibility testing on blood cultures using MALDI-TOF MS

Antibiotic resistance is a major public health problem requiring the early optimization of antibiotic prescriptions. Matrix-Assisted Laser Desorption Ionization-Time Of Flight Mass Spectrometry (MALDI-TOF MS) has been shown to accurately identify bacteria from positive blood culture. Here, we developed a rapid detection of Escherichia coli resistance to amoxicillin (AMX) and cefotaxime (CTX) from positive blood culture based on MALDI-TOF MS. Potential sparing of broad-spectrum antibiotics was also evaluated. We tested 103 E. coli-positive blood cultures. Blood cultures were subculture 1-hour in antibiotic-free rich liquid media before further incubation with and without AMX for 2.5 h or CTX for 2 h. Protein extracts associated with an internal control were spotted on a MALDI-TOF target and spectra were analyzed with the MBT-ASTRA prototype software (Bruker Daltonik GmbH, Bremen, Germany). Bacterial growth ratio was calculated from the AUC spectra obtained in the presence and absence of the antibiotic and compared to a threshold which classified E. coli as susceptible or resistant. Results were interpreted with MICs determined using agar dilution method as reference technique. MBT-ASTRA recognized 95% and 84% of the AMX- and CTX-susceptible isolates, respectively. Overall, quantitative analysis of mass spectra allows susceptibility testing within 4 hours after the positivity of blood culture with E. coli. At the first report of positive blood culture, MALDI-TOF MS would then provide the prescribers with the bacterial identification and the susceptibility to AMX and CTX, thus limiting the use of broad-spectrum compounds.