The impact of direct inoculation of ascites into blood culture bottles on ascites culture positivity.

Objective: Assess whether direct inoculation of ascites into blood culture bottles would improve ascites culture yield. Design: Pre-post-study. Setting: The study was performed at a quaternary academic medical center in Houston, Texas, including all inpatient and emergency department encounters. Patients: Ascites cultures collected from November 2020 to December 2022 were reviewed and screened for spontaneous bacterial peritonitis. Patients were excluded if a prior ascites culture from the same patient was already included in the study or if there was evidence of secondary bacterial peritonitis. Intervention: In the pre-intervention period, ascites cultures were collected into a sterile container and inoculated onto/into solid and liquid media. In the post-intervention period, ascites cultures were instead directly inoculated into bioMérieux© blood culture bottles at the bedside. Results: 114 patients met inclusion and exclusion criteria, 61 pre-intervention and 53 post-intervention. Overall ascites culture positivity was 15.8% (18/114), 11.5% (7/61) pre-intervention vs 20.8% (11/53) post-intervention. After adjusting for confounders, the intervention had a trend toward a significant effect on ascites culture positivity (P = 0.077). No significant differences were seen in time to positivity, hospital length of stay, or 30-day readmission. Conclusions: Direct inoculation of ascitic fluid into blood culture bottles led to a small increase in culture yield but lacked statistical significance. This lack of significance may be due to the study being underpowered. Further studies are required to investigate if this is due to procedural inefficiencies (eg, inadequate inoculation volumes) or pragmatic clinical practice considerations (ie, high rates of pre-culture antibiotics).

Discontinuation of contact precautions in patients with hospital-acquired MRSA and VRE infections during the COVID-19 pandemic: A multi-center experience.

Variations in the literature support the benefit of contact precautions for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) infections in the hospital setting. During personal protective equipment shortages throughout the COVID-19 pandemic, contact precautions were discontinued for MRSA and VRE-infected patients. Rates of hospital-acquired MRSA and VRE infections were compared before and after this intervention, along with hand hygiene proportions. Contact precaution discontinuation did not lead to an increase in hospital-acquired MRSA or VRE infections.

Detection of invasive Bartonella infections with next-generation sequencing of microbial cell-free DNA.

We report 9 patients with invasive Bartonella infections, including 5 with endocarditis, who were diagnosed with microbial cell-free DNA next-generation sequencing and Bartonella serology studies. Diagnosis with plasma mcfDNA NGS enabled a faster clinical and laboratory diagnosis in 8 patients. Prompt diagnosis impacted antibiotic management in all 9 patients.

The impact of a blood-culture diagnostic stewardship intervention on utilization rates and antimicrobial stewardship.

Blood-culture overutilization is associated with increased cost and excessive antimicrobial use. We implemented an intervention in the adult intensive care unit (ICU), combining education based on the DISTRIBUTE algorithm and restriction to infectious diseases and ICU providers. Our intervention led to reduced blood-culture utilization without affecting safety metrics.

Impact of gastrointestinal polymerase chain reaction panels on antibiotic utilization in hospitalized adult patients.

Multiplex stool polymerase chain reaction (PCR) panels offer rapid comprehensive testing for patients with infectious diarrhea. We compared antibiotic utilization among hospitalized patients with suspected infectious diarrhea who underwent diagnostic testing with either a stool culture or stool PCR panel. No significant differences in antibiotic utilization were identified.

The Impact of Initial Specimen Diversion Systems on Blood Culture Contamination.

Blood culture contamination is associated with increased antimicrobial use, length of stay, and hospital cost. To address this problem, blood culture diversion has been developed as an additional measure to reduce contamination to targeted goals. Three different versions were proposed, including an open technique and 2 commercially available devices. This study aims to review the existing literature and analyze evidence for these 3 techniques.

Micafungin pharmacodynamics predict clinical outcomes in hospitalized patients with candidemia caused by certain Candida species.

STUDY OBJECTIVE: Echinocandins are guideline-preferred therapies for invasive candidiasis (IC). Fixed dosing of echinocandins is commonly used despite variations in body mass index and echinocandin susceptibility. The purpose of this study was to evaluate clinical outcomes of micafungin based on population-predicted pharmacokinetic/pharmacodynamic (PK/PD) factors and susceptibility. DESIGN AND SETTING: Candida isolate results were screened from bloodstream or intraabdominal cultures of hospitalized patients admitted to a quaternary-care teaching hospital. Patients with a first episode of IC who received micafungin for at least 48 h were included. Patients with mixed cultures or Candida species with no minimum inhibitory concentration (MIC) differences were excluded. Breakpoints for micafungin MIC and area under the curve (AUC)/MIC ratio were calculated using classification and regression tree (CART) analysis and related to clinical outcomes. Primary efficacy outcome was candida-contributable mortality, defined as mortality within 28 days of positive culture with concomitant micafungin treatment failure; secondary outcome was micafungin treatment failure within 28 days, MAIN RESULTS: Seventy-two patients were included of whom 15 (21%) had Candida-contributable mortality and 34 (47%) experienced micafungin treatment failure. C. albicans and C. tropicalis did not have differing MICs and these patients were excluded from the study. Mortality using a CART-derived MIC breakpoint of ≥1.0 mg/L was 38% compared to 9% in patients infected with lower MIC strains (p = 0.003). Patients with a CART-derived AUC/MIC value >138.5 had a mortality rate of 9% compared to 41% for patients with AUC/MIC values below the breakpoint (p = 0.0013). Results were similar for treatment failure rates, and both were confirmed using multivariable models. CONCLUSIONS: CART-derived micafungin MIC and AUC/MIC breakpoints predicted patient mortality and treatment failure for certain Candida species. These results support the need for further PK/PD studies to optimize echinocandin dosing and improve patient outcomes.

The effect of a plasma next-generation sequencing test on antimicrobial management in immunocompetent and immunocompromised patients-A single-center retrospective study.

Objective: To describe the use of next-generation sequencing (NGS) and to determine whether NGS leads to changes in antimicrobial management. Design and setting: This retrospective cohort study included patients aged ≥18 years admitted to a single tertiary-care center in Houston, Texas, with an NGS test performed between January 1, 2017, and December 31, 2018. Patients: In total, 167 NGS tests were performed. Most patients were of non-Hispanic ethnicity (n = 129), white (n = 106), and male (n = 116), with a mean age of 52 years (SD, 16). Moreover, 61 patients were immunocompromised: solid-organ transplant (n = 30), patients with human immunodeficiency virus (n = 14), and rheumatology patients on immunosuppressive therapy (n = 12). Results: Of the 167 NGS tests performed, 118 (71%) were positive. Test results associated with a change in antimicrobial management were found in 120 (72%) of 167 cases, with an average of 0.32 (SD, 1.57) fewer antimicrobials after the test. The largest change in antimicrobial management was in glycopeptide use (36 discontinuations) followed by antimycobacterial drug use (27 additions among 8 patients). Also, 49 patients had negative NGS results, but only 36 patients had their antibiotics discontinued. Conclusions: Plasma NGS testing is associated with a change in antimicrobial management in most cases. We observed a decrease in glycopeptide use after NGS results, which highlights physicians' comfort in withdrawing methicillin-resistant Staphylococcus aureus (MRSA) coverage. In addition, antimycobacterial coverage increased, corresponding with early mycobacterial detection by NGS. Further studies are needed to determine effective ways to use NGS testing as an antimicrobial stewardship tool.

An integrated approach to evaluate different tetracycline derivatives for formulary decisions.

PURPOSE: Stenotrophomonas maltophilia has emerged as a critical opportunistic pathogen associated with significant morbidity and mortality. Tetracycline derivatives have been recognized as alternative treatment options, but they have varied pharmacokinetic properties. An integrated approach to different tetracycline derivatives for formulary decisions is reported. METHODS: The minimum inhibitory concentration (MIC) data from clonally diverse bloodstream S. maltophilia isolates were examined, along with the pharmacokinetic profiles of 4 tetracycline derivatives, to predict achievable pharmacodynamic exposures with standard intravenous dosing regimens. Antimicrobial therapy was assessed using the ratio of daily drug acquisition cost relative to the ratio of the free-drug area under the time-concentration curve (fAUC) to minimum inhibitory concentration (MIC) for 90% of isolates (fAUC/MIC90). RESULTS: In our analysis, minocycline had the greatest fAUC/MIC90. Doxycycline was the most financially preferred agent, as calculated using 2020 average wholesale price for base-case estimates of drug acquisition cost. CONCLUSION: An integrated evaluation for antimicrobial formulary decision-making addressed local susceptibility data, pharmacokinetics, pharmacodynamics, dosing regimens, and drug acquisition costs. This comprehensive method is more objective than the conventional approach and warrants validation.

Characteristics of Rickettsia typhi Infections Detected with Next-Generation Sequencing of Microbial Cell-Free Deoxyribonucleic Acid in a Tertiary Care Hospital.

We present 10 patients with Rickettsia typhi infection in whom next-generation sequencing of microbial cell-free deoxyribonucleic acid (mcfDNA) was used as a diagnostic tool. Rickettsia typhi mcfDNA was detected in all cases and was more rapid and specific than rickettsial serology. Rickettsia typhi mcfDNA impacted antibiotic management in 50% of patients.

Association between universal face shield in a quaternary care center and reduction of SARS-COV2 infections among healthcare personnel and hospitalized patients.

We implemented universal face shield use for all healthcare personnel upon entry to facility in order to counter an increase in SARS-COV2 cases among healthcare personnel and hospitalized patients. There was a marked reduction of infections in both healthcare personnel and hospitalized patients between pre and post intervention. Our results support universal face shield use as part of a multifaceted approach in areas of high SARS-COV2 community transmission.

MIC profiling of ceftazidime/avibactam against two carbapenemase-producing Klebsiella pneumoniae isolates.

OBJECTIVES: The aim of this study was to correlate the results of a modified susceptibility testing method with outcomes of ceftazidime/avibactam (CAZ/AVI) therapy. METHODS: Two bloodstream K. pneumoniae isolates (CAZ/AVI-susceptible) from an abdominal source were recovered from two unrelated patients. Both patients were treated with CAZ/AVI but had discordant outcomes: KP118 (eradication within 24 h) and KP286 (persistent bacteraemia for over 30 days). Carbapenemase production in the two isolates was confirmed by Carba NP test. The CAZ minimum inhibitory concentration (MIC) was determined with escalating AVI concentrations (0-16 mg/L). The concentration-response was characterised by the sigmoid inhibitory maximum effect model. The best-fit parameter values were used to predict %T > MICi associated with CAZ/AVI exposures expected in peritoneal fluid after standard dosing (2.5 g every 8 h). These CAZ/AVI exposures were simulated in a hollow-fibre infection model (HFIM), and the bacterial responses were correlated with observed clinical outcomes. RESULTS: The AVI-dependent reduction in CAZ MIC was well characterised in both bacterial isolates (r2 ≥ 0.98). In the HFIM, sustained suppression of KP118 (T > MICi = 100%) was observed over 5 days, but not with KP286 (T > MICi < 100%). These observations are consistent with the clinical course of the patients. CONCLUSIONS: The discordant patient outcomes could be potentially explained by MIC profiling of CAZ/AVI. This method appears to be more robust than conventional susceptibility testing in predicting positive clinical outcome of CAZ/AVI therapy, and the clinical utility of this approach should be further investigated.

Using clinical decision support to improve urine culture diagnostic stewardship, antimicrobial stewardship, and financial cost: A multicenter experience.

OBJECTIVE: Despite evidence to the contrary, many practitioners continue to inappropriately screen for and treat bacteria in the urine of clinically asymptomatic patients. The purpose of this study was to evaluate the impact of a new order set on the number of urine culture performed, antibiotic days of therapy (DOT), catheter-associated urinary tract infections (CAUTI), and associated financial impact. DESIGN: A quasi-experimental before-and-after intervention. SETTING: We conducted this study at 5 Catholic Health Initiative (CHI) hospitals in Texas that use the same electronic health record (EHR) system. PATIENTS: The study populations included adult patients who had urine culture performed from June 2017 to June 2019. INTERVENTION: The intervention (implemented June 25, 2018) was the addition of a new order set in the electronic health record that required practitioners to choose an indication for the type of urine study. The primary outcome was number of urine cultures performed adjusted for the number of total patient days. RESULTS: Following implementation of the new order set, the number of urine cultures performed among the 5 sites decreased from 1,175.8 tests per 10,000 patient days before the intervention to 701.4 after the intervention (40.4% reduction; P < .01). Antibiotic DOT for patients with a urinary tract infection indication decreased from 102.5 to 86.9 per 1,000 patient days (15.2% reduction; P < .01). The CAUTI standardized infection ratio was 1.0 before the intervention and 0.8 after the intervention (P = .23). The estimated yearly savings following the intervention was US$535,181. CONCLUSIONS: The addition of a new order set resulted in decreases in the number of urine cultures performed and the antibiotic DOT, as well as substantial financial savings.

Prevalence and predictors of spontaneous bacterial peritonitis due to ceftriaxone-resistant organisms at a large tertiary centre in the USA.

OBJECTIVES: The epidemiology of spontaneous bacterial peritonitis (SBP) due to ceftriaxone-resistant organisms has not been well studied in the USA. The primary objective of this study was to assess the prevalence and predictors of ceftriaxone-resistant SBP at a large US tertiary-care centre. METHODS: This 1:1:4 case-case-control study included 141 adults with liver cirrhosis admitted from November 2011 to March 2016. Case group 1 were patients with SBP with a ceftriaxone-resistant organism (n=21). Case group 2 were patients with SBP with a ceftriaxone-susceptible organism (n=26). The control group were patients without SBP (n=94). Multiple logistic regression analysis was used to identify predictors of ceftriaxone-resistant SBP. RESULTS: Fifty isolates were identified from 47 patients with culture-positive SBP (case groups 1 and 2). Of these 50 isolates, 32 (64%) were Gram-negatives [mostly Enterobacteriaceae (91%)], 15 (30%) were Gram-positives and 3 (6%) were Candida spp. The prevalence of ceftriaxone resistance in patients with culture-positive SBP was 45% (21/47). The most common ceftriaxone-resistant organisms were ESBL-producing Enterobacteriaceae (45%). Independent predictors of ceftriaxone-resistant SBP included duration of ß-lactam therapy in the past 90days (aOR=1.07, 95% CI 1.01-1.13) and recent invasive gastrointestinal procedure (aOR=12.47, 95% CI 2.74-56.67). CONCLUSIONS: The prevalence of ceftriaxone-resistant SBP was significant at a US tertiary centre. Local epidemiological data and identification of risk factors associated with ceftriaxone-resistant SBP, e.g. increased usage of previous ß-lactam therapy and invasive gastrointestinal procedure, may help clinicians identify patients requiring alternative empirical antibiotics.

Prevalence of extended-spectrum beta-lactamase and carbapenemase-producing bloodstream isolates of Klebsiella pneumoniae in a tertiary care hospital.

To improve prescribing of empiric therapy, the local molecular epidemiology of extended-spectrum beta-lactamases (ESBLs) and Klebsiella pneumoniae carbapenemases (KPCs) in bloodstream isolates of K. pneumoniae were evaluated. Isolates resistant to third generation cephalosporins were screened phenotypically for ESBLs and carbapenemases, and subsequently confirmed by PCR for the presence of ESBL (blaTEM, blaSHV and blaCTX-M) and carbapenemase (blaKPC, blaVIM, blaNDM and blaOXA-48) genes. Hydrolytic activity (functional gene expression) was quantified using a nitrocefin degradation assay and correlated to ceftazidime or meropenem MIC. Clonality was assessed by repetitive element-based PCR. Beta-lactamases were functionally expressed in 13 isolates (15.5%); 7 (53.8%) harboured blaCTX-M-15 and 6 (46.2%) carried the blaKPC-2 gene. Correlation of hydrolytic activity to MIC yielded a coefficient of 98% for isolates expressing ESBLs alone and 56% for carbapenemase producers. Four unique ESBL-expressing clones and five carbapenem-resistant clones were identified. All 13 resistant isolates were susceptible to ceftazidime/avibactam (MIC ≤ 8/4 mg/L).

Activity of minocycline against Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae clinical isolates, with comparison to doxycycline and tigecycline.

We examined the in vitro activity of minocycline against 103 Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae isolates and found approximately half had susceptible (26%) or intermediate (26%) MICs. For a subset of 35 isolates, susceptibility was highest to tigecycline (71% FDA vs. 20% EUCAST) followed by minocycline (14%) and then doxycycline (6%).

Disseminated coccidioidomycosis with multifocal musculoskeletal disease involvement.

We report a rare case of disseminated coccidioidomycosis with multifocal musculoskeletal involvement. The patient presented to the emergency department with left shoulder pain and swelling. Magnetic resonance imaging of the left shoulder revealed enhancing soft tissue masses, bony lesions, and fluid collections in and around the glenohumeral joint with involvement of the proximal humerus, glenoid, and rotator cuff musculature. Multiple additional areas of involvement were subsequently discovered. Fungal cultures confirmed coccidioidomycosis infection at all surgical sites with superimposed polymicrobial bacterial infection in the left shoulder.