Predictive model of antimicrobial-resistant Gram-negative bacteremia at the ED

Peripartum Infections: A Position Statement of the Indian Society of Critical Care Medicine

This position statement reviews the evidence and rationale for the management of severe peripartum infections with a special focus on tropical infections and is tailored for resource-limited settings.

HOW TO CITE THIS ARTICLE

Samavedam S, Sodhi K, Anand P, Bajwa SJS, Karnad DR, Karanth S, et al. Peripartum Infections: A Position Statement of the Indian Society of Critical Care Medicine. Indian J Crit Care Med 2024;28(S2):S92-S103.

Antibiotic Skin Testing in the Intensive Care Unit: A Systematic Review

BACKGROUND

Recent research has shown that a large majority of patients with a history of penicillin allergy are acutely tolerant of penicillins and that there is no clinically significant immunologic cross-reactivity between penicillins and cephalosporins or other β-lactams. The standard test to confirm acute tolerance is challenge with a therapeutic dose. Skin testing is useful only when the culprit antibiotic can haptenate serum proteins and induce an immunoglobulin E-mediated reaction and the clinical history demonstrates such high risk that a direct oral challenge may result in anaphylaxis.

OBJECTIVE

To review and evaluate the current practice of skin testing for antibiotics (other than penicillin) in critically ill patients by means of a systematic literature review.

METHODS

This systematic review was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. Several electronic databases were searched using the following terms: antibiotics, skin test (tests, testing), intensive care, intensive care unit, ICU, critical care, critical care unit.

RESULTS

Twenty-three articles were identified for inclusion in this review. The results indicate a lack of standardized skin testing for all antibiotics in critical care settings. Oral challenge with nonirritating concentrations of antibiotics can be helpful in determining allergy to these drugs.

CONCLUSIONS

Critical care providers should evaluate antibiotic allergy using nonirritating concentrations before administering antibiotics to patients. Introduction of a standardized skin test for all antibiotics in intensive care unit patients to help select the most appropriate antibiotic treatment regimen might help save lives and reduce costs.

Using local clinical and microbiological data to develop an institution specific carbapenem-sparing strategy in sepsis: a nested case-control study

Background

From a stewardship perspective it is recommended that antibiotic guidelines are adjusted to the local setting, accounting for the local epidemiology of pathogens. In many settings the prevalence of Gram-negative pathogens with resistance to empiric sepsis therapy is increasing. How and when to escalate standard sepsis therapy to a reserve antimicrobial agent, is a recurrent dilemma. The study objective was to develop decision strategies for empiric sepsis therapy based on local microbiological and clinical data, and estimate the number needed to treat with a carbapenem to avoid mismatch of empiric therapy in one patient (NNTC).

Methods

We performed a nested case control study in patients (> 18 years) with Gram-negative bacteremia in 2013-2016. Cases were defined as patients with Gram-negative bacteremia with in vitro resistance to the combination 2nd generation cephalosporin AND aminoglycoside (C-2GC + AG). Control patients had Gram-negative bacteremia with in vitro susceptibility to cefuroxime AND/OR gentamicin, 1:2 ratio. Univariate and multivariable analysis was performed for demographic and clinical predictors of resistance. The adequacy rates of empiric therapy and the NNTC were estimated for different strategies.

Results

The cohort consisted of 486 episodes of Gram-negative bacteremia in 450 patients. Median age was 66 years (IQR 56-74). In vitro resistance to C-2GC + AG was present in 44 patients (8.8%). Independent predictors for resistance to empiric sepsis therapy were hematologic malignancy (adjusted OR 4.09, 95%CI 1.43-11.62, p < 0.01), previously cultured drug resistant pathogen (adjusted OR 3.72. 95%CI 1.72-8.03, p < 0.01) and antibiotic therapy during the preceding 2 months (adjusted OR 12.5 4.08-38.48, p < 0.01). With risk-based strategies, an adequacy rate of empiric therapy of 95.2-99.3% could be achieved. Compared to treating all patients with a carbapenem, the NNTC could be reduced by 82.8% (95%CI 78.5-87.5%) using the targeted approaches.

Conclusions

A risk-based approach in empiric sepsis therapy has the potential to better target the use of reserve antimicrobial agents aimed at multi-resistant Gram-negative pathogens. A structured evaluation of the expected antimicrobial consumption and antibiotic adequacy rates is essential to be able to weigh the costs and benefits of potential antibiotic strategies and select the most appropriate approach.

The Rapid Prediction of Carbapenem Resistance in Patients With Klebsiella pneumoniae Bacteremia Using Electronic Medical Record Data

BACKGROUND

The administration of active antibiotics is often delayed in cases of carbapenem-resistant gram-negative bacteremia. Using electronic medical record (EMR) data to rapidly predict carbapenem resistance in patients with Klebsiella pneumoniae bacteremia could help reduce the time to active therapy.

METHODS

All cases of Klebsiella pneumoniae bacteremia at Mount Sinai Hospital from September 2012 through September 2016 were included. Cases were randomly divided into a "training set" and a "testing set." EMR data from the training set cases were reviewed, and significant risk factors for carbapenem resistance were entered into a multiple logistic regression model. Performance was assessed by repeated K-fold cross-validation and by applying the training set model to the testing set. All cases were also reviewed to determine the time to effective antibiotic therapy.

RESULTS

A total of 613 cases of Klebsiella pneumoniae bacteremia were included, 61 (10%) of which were carbapenem-resistant. The training and testing sets consisted of 460 and 153 cases, respectively. The regression model derived from the training set correctly predicted 73% of carbapenem-resistant cases and 59% of carbapenem-susceptible cases in the testing set (sensitivity, 73%; specificity, 59%; positive predictive value, 16%; negative predictive value, 95%). The mean area under the receiver operator characteristic curve of the K-fold cross-validation repeats was 0.731. Patients with carbapenem-resistant infections received active antibiotics significantly later than those with susceptible infections (40.4 hours vs 9.6 hours, P < .0001).

CONCLUSIONS

A multiple logistic regression model using EMR data can generate rapid, sensitive predictions of carbapenem resistance in patients with Klebsiella pneumoniae bacteremia, which could help shorten the time to effective therapy in these cases.

Decision-support models for empiric antibiotic selection in Gram-negative bloodstream infections

OBJECTIVES

Early empiric antibiotic therapy in patients can improve clinical outcomes in Gram-negative bacteraemia. However, the widespread prevalence of antibiotic-resistant pathogens compromises our ability to provide adequate therapy while minimizing use of broad antibiotics. We sought to determine whether readily available electronic medical record data could be used to develop predictive models for decision support in Gram-negative bacteraemia.

METHODS

We performed a multi-centre cohort study, in Canada and the USA, of hospitalized patients with Gram-negative bloodstream infection from April 2010 to March 2015. We analysed multivariable models for prediction of antibiotic susceptibility at two empiric windows: Gram-stain-guided and pathogen-guided treatment. Decision-support models for empiric antibiotic selection were developed based on three clinical decision thresholds of acceptable adequate coverage (80%, 90% and 95%).

RESULTS

A total of 1832 patients with Gram-negative bacteraemia were evaluated. Multivariable models showed good discrimination across countries and at both Gram-stain-guided (12 models, areas under the curve (AUCs) 0.68-0.89, optimism-corrected AUCs 0.63-0.85) and pathogen-guided (12 models, AUCs 0.75-0.98, optimism-corrected AUCs 0.64-0.95) windows. Compared to antibiogram-guided therapy, decision-support models of antibiotic selection incorporating individual patient characteristics and prior culture results have the potential to increase use of narrower-spectrum antibiotics (in up to 78% of patients) while reducing inadequate therapy.

CONCLUSIONS

Multivariable models using readily available epidemiologic factors can be used to predict antimicrobial susceptibility in infecting pathogens with reasonable discriminatory ability. Implementation of sequential predictive models for real-time individualized empiric antibiotic decision-making has the potential to both optimize adequate coverage for patients while minimizing overuse of broad-spectrum antibiotics, and therefore requires further prospective evaluation.

SUMMARY

Readily available epidemiologic risk factors can be used to predict susceptibility of Gram-negative organisms among patients with bacteraemia, using automated decision-making models.

Predictive utility of prior positive urine cultures

BACKGROUND

A patient's prior urine cultures are often considered when choosing empiric antibiotic therapy for a suspected urinary tract infection. We sought to evaluate how well previous urine cultures predict the identity and susceptibility of organisms in a patient's subsequent urine cultures.

METHODS

We conducted a multinational, multicenter, retrospective cohort study, including 22 019 pairs of positive urine cultures from 4351 patients across 2 healthcare systems in Toronto, Ontario, and Chicago, Illinois. We examined the probability of the same organism being identified from the same patient's positive urine culture as a function of time elapsed from the previous positive urine specimen; in cases where the same organism was identified we also examined the likelihood of the organism exhibiting the same or better antimicrobial susceptibility profile.

RESULTS

At 4-8 weeks between cultures, the correspondence in isolate identity was 57% (95% confidence interval [CI], 55%-59%), and at >32 weeks it was 49% (95% CI, 48%-50%), still greater than expected by chance (P < .001). The susceptibility profile was the same or better in 83% (95% CI, 81%-85%) of isolate pairs at 4-8 weeks, and 75% (95% CI, 73%-77%) at >32 weeks, still greater than expected by chance (P < .001). Despite high local rates of ciprofloxacin resistance in urine isolates across all patients (40%; 95% CI, 39.5%-40.5%), ciprofloxacin resistance was <20% among patients with a prior ciprofloxacin sensitive organism and no subsequent fluoroquinolone exposure.

CONCLUSIONS

A patient's prior urine culture results are useful in predicting the identity and susceptibility of a current positive urine culture. In areas of high fluoroquinolone resistance, ciprofloxacin can be used empirically when prior urine culture results indicate a ciprofloxacin-susceptible organism and there has been no history of intervening fluoroquinolone use.

Utility of prior screening for methicillin-resistant Staphylococcus aureus in predicting resistance of S. aureus infections

BACKGROUND

Screening for methicillin-resistant Staphylococcus aureus (MRSA) is intended to reduce nosocomial spread by identifying patients colonized by MRSA. Given the widespread use of this screening, we evaluated its potential clinical utility in predicting the resistance of clinical isolates of S. aureus.

METHODS

We conducted a 2-year retrospective cohort study that included patients with documented clinical infection with S. aureus and prior screening for MRSA. We determined test characteristics, including sensitivity and specificity, of screening for predicting the resistance of subsequent S. aureus isolates.

RESULTS

Of 510 patients included in the study, 53 (10%) had positive results from MRSA screening, and 79 (15%) of infecting isolates were resistant to methicillin. Screening for MRSA predicted methicillin resistance of the infecting isolate with 99% (95% confidence interval [CI] 98%-100%) specificity and 63% (95% CI 52%-74%) sensitivity. When screening swabs were obtained within 48 hours before isolate collection, sensitivity increased to 91% (95% CI 71%-99%) and specificity was 100% (95% CI 97%-100%), yielding a negative likelihood ratio of 0.09 (95% CI 0.01-0.3) and a negative predictive value of 98% (95% CI 95%-100%). The time between swab and isolate collection was a significant predictor of concordance of methicillin resistance in swabs and isolates (odds ratio 6.6, 95% CI 1.6-28.2).

INTERPRETATION

A positive result from MRSA screening predicted methicillin resistance in a culture-positive clinical infection with S. aureus. Negative results on MRSA screening were most useful for excluding methicillin resistance of a subsequent infection with S. aureus when the screening swab was obtained within 48 hours before collection of the clinical isolate.

Isolated pathogens and clinical outcomes of adult bacteremia in the emergency department: a retrospective study in a tertiary Referral Center

BACKGROUND

Approximately two-thirds of the patients with severe sepsis or septic shock are first encountered in the emergency departments (EDs) of western countries, in which bacteremia is present in about 50% of patients with severe sepsis. The situation of bacteremia presenting to the EDs in Taiwan is not well documented. The objective of this study was to examine the epidemiology and microbiology of bacteremia in adult patients who visited the ED of a medical center in southern Taiwan.

METHODS

A retrospective observational study of the epidemiology and microbiology of bacteremia was conducted in the ED of a medical center involving 6,137 adult patients and 13,903 blood cultures.

RESULTS

A total of 831 consecutive patients with 890 episodes of bacteremia were obtained from January 1 to December 31, 2004, indicating a positive culture rate of 13.5% (1,872/13,903). Among these episodes, 525 (59%) were defined as true community-acquired infections followed by 263 (29.5%) as health care-associated infections and 102 (11.5%) as nosocomial infections. Of the 972 isolates, 289 (29.7%) were gram-positive species and 683 (70.3%) were gram-negative species. Urinary tract infections (32.2%, 287/890) were most common in these patients, with Escherichia coli (30.8%, 299/972) being the most common pathogen. Bacteremia caused by Staphylococcus aureus was more common in nosocomial than true community-acquired infections (31.3% vs. 12%) and had significantly higher possibility of resistance to methicillin in infections not purely acquired from community (odds ratio = 24.92; 95% confidence interval, 9.88-62.87). The overall crude mortality rate was 21% and nearly half of the mortalities occurred within 3 days of visiting the ED. All patients discharged inadvertently were uneventful (n = 65, two lost at follow-up).

CONCLUSIONS

Categories of bacteremia acquisition was associated with different distribution of pathogens, antimicrobial resistance, and clinical outcome. Traditional classification might overestimate the problem of drug resistance in community-acquired infections. The concept of health care-associated infection should be introduced to avoid overemphasis of drug-resistant problem in true community-acquired infection.

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