From Epidemiology of Community-Onset Bloodstream Infections to the Development of Empirical Antimicrobial Treatment-Decision Algorithm in a Region with High Burden of Antimicrobial Resistance

Antimicrobial-resistant (AMR) infections have increased in community settings. Our objectives were to study the epidemiology of community-onset bloodstream infections (BSIs), identify risk factors for AMR-BSI and mortality-related factors, and develop the empirical antimicrobial treatment-decision algorithm. All adult, positive blood cultures at the emergency room and outpatient clinics were evaluated from 08/2021 to 04/2022. AMR was defined as the resistance of organisms to an antimicrobial to which they were previously sensitive. A total of 1151 positive blood cultures were identified. There were 450 initial episodes of bacterial BSI, and 114 BSIs (25%) were AMR-BSI. Non-susceptibility to ceftriaxone was detected in 40.9% of 195 E. coli isolates and 16.4% among 67 K. pneumoniae isolates. A treatment-decision algorithm was developed using the independent risk factors for AMR-BSI: presence of multidrug-resistant organisms (MDROs) within 90 days (aOR 3.63), prior antimicrobial exposure within 90 days (aOR 1.94), and urinary source (aOR 1.79). The positive and negative predictive values were 53.3% and 83.2%, respectively. The C-statistic was 0.73. Factors significantly associated with 30-day all-cause mortality were Pitt bacteremia score (aHR 1.39), solid malignancy (aHR 2.61), and urinary source (aHR 0.30). In conclusion, one-fourth of community-onset BSI were antimicrobial-resistant, and one-third of Enterobacteriaceae were non-susceptible to ceftriaxone. Treatment-decision algorithms may reduce overly broad antimicrobial treatment.

ACORN (A Clinically-Oriented Antimicrobial Resistance Surveillance Network) II: protocol for case based antimicrobial resistance surveillance

Background: Antimicrobial resistance surveillance is essential for empiric antibiotic prescribing, infection prevention and control policies and to drive novel antibiotic discovery. However, most existing surveillance systems are isolate-based without supporting patient-based clinical data, and not widely implemented especially in low- and middle-income countries (LMICs). Methods: A Clinically-Oriented Antimicrobial Resistance Surveillance Network (ACORN) II is a large-scale multicentre protocol which builds on the WHO Global Antimicrobial Resistance and Use Surveillance System to estimate syndromic and pathogen outcomes along with associated health economic costs. ACORN-healthcare associated infection (ACORN-HAI) is an extension study which focuses on healthcare-associated bloodstream infections and ventilator-associated pneumonia. Our main aim is to implement an efficient clinically-oriented antimicrobial resistance surveillance system, which can be incorporated as part of routine workflow in hospitals in LMICs. These surveillance systems include hospitalised patients of any age with clinically compatible acute community-acquired or healthcare-associated bacterial infection syndromes, and who were prescribed parenteral antibiotics. Diagnostic stewardship activities will be implemented to optimise microbiology culture specimen collection practices. Basic patient characteristics, clinician diagnosis, empiric treatment, infection severity and risk factors for HAI are recorded on enrolment and during 28-day follow-up. An R Shiny application can be used offline and online for merging clinical and microbiology data, and generating collated reports to inform local antibiotic stewardship and infection control policies. Discussion: ACORN II is a comprehensive antimicrobial resistance surveillance activity which advocates pragmatic implementation and prioritises improving local diagnostic and antibiotic prescribing practices through patient-centred data collection. These data can be rapidly communicated to local physicians and infection prevention and control teams. Relative ease of data collection promotes sustainability and maximises participation and scalability. With ACORN-HAI as an example, ACORN II has the capacity to accommodate extensions to investigate further specific questions of interest.

Predictive Value of Urinalysis and Recent Antibiotic Exposure to Distinguish Between Bacteriuria, Candiduria, and No-Growth Urine

PURPOSE

Urinary tract infections are diagnosed by clinical symptoms and detection of causative uropathogen. Antibiotics are usually not indicated in candiduria and no-growth urine. We aimed to develop a predictive score to distinguish bacteriuria, candiduria, and no-growth urine, and to describe the distribution of microorganisms in urine.

PATIENTS AND METHODS

A single-center, retrospective cohort study was conducted between January 2017 and November 2017. Patients with concomitant urinalysis and urine culture were randomly sorted for a clinical prediction model. Multivariable regression analysis was performed to determine factors associated with bacteriuria, candiduria, and no-growth urine. A scoring system was constructed by rounding the regression coefficient for each predictor to integers. Accuracy of the score was measured by the concordance index (c-index).

RESULTS

There were 8091 positive urine cultures: bacteria 85.6%, Candida 13.7%. Randomly selected cases were sorted into derivation and validation cohorts (448 cases and 272 cases, respectively). Numerous yeast on urinalysis predicted candiduria with complete accuracy; therefore, it was excluded from a score construction. We developed a NABY score based on: positive nitrite, 1 point; Antibiotic exposure within 30 days, -2 points; numerous Bacteria in urine, 2 points; few Yeast in urine, -2 points; moderate Yeast in urine, -5 points. The c-index was 0.85 (derivation) and 0.82 (validation). A score ≥0 predicted 76% and 54% of bacteriuria in the derivation and validation cohorts, respectively. A score ≤-3 predicted 96% of candiduria in both cohorts.

CONCLUSION

Numerous yeast on urinalysis and the NABY score may help identify patients with a low risk of bacteriuria in whom empiric antibiotics for UTIs can be avoided.

Performance of real-time PCR and immunofluorescence assay for diagnosis of Pneumocystis pneumonia in real-world clinical practice

Background

PCR is more sensitive than immunofluorescence assay (IFA) for detection of Pneumocystis jirovecii. However, PCR cannot always distinguish infection from colonization. This study aimed to compare the performance of real-time PCR and IFA for diagnosis of P. jirovecii pneumonia (PJP) in a real-world clinical setting.

Methods

A retrospective cohort study was conducted at a 1,300-bed hospital between April 2017 and December 2018. Patients whose respiratory sample (bronchoalveolar lavage or sputum) were tested by both Pneumocystis PCR and IFA were included. Diagnosis of PJP was classified based on multicomponent criteria. Sensitivity, specificity, 95% confidence intervals (CI), and Cohen's kappa coefficient were calculated.

Results

There were 222 eligible patients. The sensitivity and specificity of PCR was 91.9% (95% CI, 84.0%–96.7%) and 89.7% (95% CI, 83.3%–94.3%), respectively. The sensitivity and specificity of IFA was 7.0% (95% CI, 2.6%–14.6%) and 99.2% (95% CI, 95.6%–100.0%), respectively. The percent agreement between PCR and IFA was 56.7% (Cohen's kappa -0.02). Among discordant PCR-positive and IFA-negative samples, 78% were collected after PJP treatment. Clinical management would have changed in 14% of patients using diagnostic information, mainly based on PCR results.

Conclusions

PCR is highly sensitive compared with IFA for detection of PJP. Combining clinical, and radiological features with PCR is useful for diagnosis of PJP, particularly when respiratory specimens cannot be promptly collected before initiation of PJP treatment.

Epidemiology of carbapenem-resistant Enterobacteriaceae: a 5-year experience at a tertiary care hospital

Purpose

The incidence of carbapenem-resistant Enterobacteriaceae (CRE) has been increasing worldwide. Ertapenem resistance is mediated by non-carbapenemase mechanisms, and has less of an effect on susceptibility to imipenem and meropenem. This study aimed to study the epidemiology of CRE, and to compare risk factors and related mortality between non-susceptibility to ertapenem alone Enterobacteriaceae (NSEE), with non-susceptibility to other carbapenems (imipenem, meropenem, or doripenem) Enterobacteriaceae (NSOCE) at a tertiary care hospital in Thailand.

Methods

All CRE isolated were identified between December 2011 and December 2016. Quarterly incidence rate was estimated. Hospital-wide carbapenem consumption was calculated as defined daily doses (DDD). Relationships between hospital-wide carbapenem consumption and incidence of CRE were tested. Factors associated with NSEE and NSOCE, and risk factors associated with 14- and 30-day mortality in patients with CRE infection were determined.

Results

The quarterly CRE incidence increased significantly from 3.37 per 100,000 patient-days in the last quarter of 2011 to 32.49 per 100,000 patient-days in the last quarter of 2016. (P for trend <0.001). Quarterly hospital-wide carbapenem consumption increased 1.58 DDD per 1,000 patient-days (P for trend=0.004). The Poisson regression showed the expected increase of CRE incidence was 1.02 per 100,000 patient-days for a 1 DDD per 1,000 patient-days increase in carbapenem consumption (P<0.001). There were 40 patients with NSEE and 134 patients with NSOCE in the 5-year study period. The NSEE group had significantly lower carbapenem exposure compared with the NSOCE group (adjusted odds ratio: 0.25; P=0.001). No difference in 14-day and 30-day all-cause mortality between the two groups was observed.

Conclusion

The incidence of CRE has risen significantly at our institution. Previous carbapenem use was associated with NSOCE. This hospital-wide carbapenem use was significantly associated with the increasing incidence of CRE.

1174. Epidemiology of Carbapenem-Resistant Enterobacteriaceae, a 5-Year Experience at a Tertiary Care Hospital

Background

Methods

Results

Conclusion

Disclosures

Prevalence of HIV infection, access to HIV care, and response to antiretroviral therapy among partners of HIV-infected individuals in Thailand

Background

Health care providers usually focus on index HIV-infected patients and seldom obtain information from their partners. We aimed to determine HIV-preventative measures among couples, the prevalence of HIV infection, and treatment outcomes of partners.

Methods

This cross-sectional study was conducted in two hospital settings, a university hospital in Bangkok and a general hospital in northeastern Thailand, from January 2011-October 2015. Factors associated with serodiscordant relationships were determined by logistic regression.

Results

A total of 393 couples were enrolled for analysis; 156 (39.7%) were serodiscordant. The median relationship duration of serodiscordant couples was shorter than that of seroconcordant couples (6.4 years vs 11.6 years, p < 0.001). Of 237 HIV-infected partners, 17.7% had AIDS-defining illness, the median nadir CD4 count (interquartile range) was 240 (96–427) cells/mm³, 83.5% received antiretroviral therapy (ART), 98.3% had adherence > 95%, 90.3% had undetectable HIV RNA, and 22.9% had a prior history of treatment failure. There was no significant difference in condom usage in the prior 30 days between serodiscordant and seroconcordant couples. Factors of index HIV-infected patients associated with serodiscordant relationships were younger age (odds ratio [OR] 1.04 per 5 years; 95% confidence interval [CI] 1.01–1.06), receiving care at the general hospital (OR 1.73; 95% CI 1.08–2.78), a shorter duration of relationship (OR 1.04 per year; 95% CI 1.01–1.07), a higher nadir CD4 count (OR 1.06 per 50 cells/mm³; 95% CI 1.1–1.13), and not receiving a protease inhibitor-based regimen (OR 2.04; 95% CI 1.06–3.96).

Conclusions

A high number of serodiscordant couples was determined. Partners’ information should be retrieved as a holistic approach. Interventions for minimizing HIV transmission within serodiscordant couples should be evaluated and implemented.

Comparing the Outcomes of Adults With Enterobacteriaceae Bacteremia Receiving Short-Course Versus Prolonged-Course Antibiotic Therapy in a Multicenter, Propensity Score-Matched Cohort

Background

The recommended duration of antibiotic treatment for Enterobacteriaceae bloodstream infections is 7-14 days. We compared the outcomes of patients receiving short-course (6-10 days) vs prolonged-course (11-16 days) antibiotic therapy for Enterobacteriaceae bacteremia.

Methods

A retrospective cohort study was conducted at 3 medical centers and included patients with monomicrobial Enterobacteriaceae bacteremia treated with in vitro active therapy in the range of 6-16 days between 2008 and 2014. 1:1 nearest neighbor propensity score matching without replacement was performed prior to regression analysis to estimate the risk of all-cause mortality within 30 days after the end of antibiotic treatment comparing patients in the 2 treatment groups. Secondary outcomes included recurrent bloodstream infections, Clostridium difficile infections (CDI), and the emergence of multidrug-resistant gram-negative (MDRGN) bacteria, all within 30 days after the end of antibiotic therapy.

Results

There were 385 well-balanced matched pairs. The median duration of therapy in the short-course group and prolonged-course group was 8 days (interquartile range [IQR], 7-9 days) and 15 days (IQR, 13-15 days), respectively. No difference in mortality between the treatment groups was observed (adjusted hazard ratio [aHR], 1.00; 95% confidence interval [CI], .62-1.63). The odds of recurrent bloodstream infections and CDI were also similar. There was a trend toward a protective effect of short-course antibiotic therapy on the emergence of MDRGN bacteria (odds ratio, 0.59; 95% CI, .32-1.09; P = .09).

Conclusions

Short courses of antibiotic therapy yield similar clinical outcomes as prolonged courses of antibiotic therapy for Enterobacteriaceae bacteremia, and may protect against subsequent MDRGN bacteria.

The Role of Negative Methicillin-Resistant Staphylococcus aureus Nasal Surveillance Swabs in Predicting the Need for Empiric Vancomycin Therapy

Background

The role of MRSA nasal surveillance swabs in guiding decisions about need for subsequent vancomycin therapy is unclear. Our objectives were to (1) determine the likelihood that patients with negative MRSA nasal swabs went on to develop MRSA infections during the same hospitalizations to assess if vancomycin therapy could be avoided once the nasal swab result returns negative, (2) assess days of vancomycin that potentially could be avoided, and (3) identify risk factors for having a negative MRSA nasal swab and developing an MRSA infection during the hospital stay.

Methods

This retrospective cohort study was conducted at six intensive care units (ICUs) at a tertiary care hospital in Baltimore from December 2013 to June 2015. MRSA nasal swabs are obtained at the time of admission and weekly thereafter for all ICU patients. The negative predictive value (NPV), defined as the ability of a negative MRSA nasal screening test to correctly predict no subsequent MRSA infection during the hospital stay, was calculated, accounting for the 3-day turnaround time of MRSA nasal surveillance swabs. Days of vancomycin therapy started or continued after 3 days from the first negative MRSA nasal swab were determined by chart review. A matched case–control study was performed to identify risk factors for patients with negative MRSA surveillance cultures who subsequently developed MRSA infections.

Results

Of 11,441 MRSA-nasal swab negative patients, the proportion of subsequent incident MRSA infections was 0.2%. Negative MRSA surveillance swabs had an NPV of 99.4% (95% CI 99.1–99.6%). Among 4,091 MRSA-negative patients receiving vancomycin, vancomycin was started or continued after 3 days since the first MRSA-negative nasal swab in 1,434 patients (35%), translating to 7,377 potentially avoidable vancomycin days. The matched case–control analysis did not identify risk factors associated with subsequent MRSA infection.

Conclusion

At our institution with robust infection control practices and low nosocomial MRSA transmission rates, patients with negative MRSA nasal swabs have a very low likelihood of subsequent MRSA infection during hospitalizations. MRSA nasal swabs can provide useful information when determining whether to initiate or stop empiric vancomycin.

Disclosures

All authors: No reported disclosures.

Comparing the Outcomes of Adults with Enterobacteriaceae Bacteremia Receiving Short-Course vs Prolonged-Course Antibiotic Therapy

Background

The recommended duration of antibiotic treatment for Enterobacteriaceae bacteremia is between 7 and 14 days. We compared the clinical outcomes of patients receiving short-course (6–10 days) vs prolonged-course (11–15 days) antibiotic therapy for Enterobacteriaceae bacteremia.

Methods

A retrospective cohort study was conducted at The Johns Hopkins Hospital, The University of Maryland Medical Center, and The Hospital of the University of Pennsylvania including patients with monomicrobial Enterobacteriaceae bacteremia treated with in vitro active antibiotic therapy in the range of 6–15 days between 2008 and 2014. 1:1 nearest neighbor propensity score matching without replacement was performed, prior to regression analysis, to estimate the risk of all-cause mortality within 30 days after the end of antibiotic treatment for patients receiving short vs. prolonged durations of antibiotic therapy. Secondary outcomes included Clostridium difficile infection (CDI) and the emergence of multidrug-resistant Gram-negative (MDRGN) bacteria within 30 days after the end of antibiotic therapy.

Results

A total of 1,769 patients met eligibility criteria. There were 385 matched pairs who were well-balanced on baseline characteristics. The median duration of therapy in the short-course group and prolonged-course group was 8 days (interquartile range (IQR) 7–9 days) and 15 days (IQR 13–15 days), respectively. No difference in all-cause mortality between short- and prolonged-course treatment groups was observed (adjusted hazard ratio [aHR] 1.00; 95% CI 0.62–1.63). Rates of CDI were similar between the treatment groups (OR 1.17; 95% CI 0.39–3.51). There was a non-significant protective effect of short-course antibiotic therapy on the emergence of MDRGN bacteria (OR 0.59; 95% CI 0.32–1.09 P = 0.09).

Conclusion

Short courses of antibiotic therapy yields similar clinical outcomes to prolonged courses of antibiotic therapy for Enterobacteriaceae bacteremia, and may protect against subsequent MDRGN emergence.

Disclosures

All authors: No reported disclosures.

EPIDEMIOLOGY AND CONTROL OF THE FIRST REPORTED VANCOMYCIN-RESISTANT ENTEROCOCCUS OUTBREAK AT A TERTIARY-CARE HOSPITAL IN BANGKOK, THAILAND

This retrospective study described the first reported vancomycin-resistant enterococci (VRE) outbreak from June 2013 through January 2014 at a tertiary-care hospital in Bangkok, Thailand. After the index case was detected in an 18-bed medical intermediate care unit, a number of interventions was implemented, including targeted active surveillance for VRE, strict contact precautions, enhanced standard precautions, dedicated units for VRE cases, extensive cleaning of the environment and the restricted use of antibiotics. VRE isolates were evaluated by polymerase chain reaction and random amplified polymorphic DNA (RAPD) testing. A prevalence case-control study was conducted. Among 3,699 culture samples from 2,671 patients screened, 74 patients (2.8%) had VRE. The positivity rate declined from 15.1% during week 1 to 8.2% during week 2 and then 1.4% during week 3. By weeks 4-9, the prevalences were 0-2.7%. However, the prevalence rose to 9.4% during week 10 and then subsequently declined. All VRE isolates were Enterococcus faecium and had the vanA gene. RAPD analysis revealed a single predominant clone. Multivariate analysis showed mechanical ventilation for ≥ 7 days was a predictive factor for VRE colonization [odds ratio (OR) 11.47; 95% confidence interval (CI): 1.75-75.35; p = 0.011]. This experience demonstrates VRE can easily spread and result in an outbreak in multiple-bed units. Active surveillance, early infection control interventions and rapid patient cohorting were important tools for control of this outbreak. Patients requiring mechanical ventilator for ≥ 7 days were at higher risk for VRE acquisition.

Arcanobacterium pyogenes endocarditis: a case report and literature review

We report the case of a 64-year-old man with Arcanobacterium pyogenes endocarditis. The patient presented with dyspnea and asymmetrical progressive quadriparesis. A transthoracic echocardiogram revealed mobile vegetations on both leaflets of his mitral valve measuring 0.5 x 3 cm, thickening of the mitral valve with severe mitral regurgitation due to dehiscence of the papillary muscle to the posterior mitral leaflet. He also had aortic sclerosis with a vegetation measuring 0.5 x 1 cm causing aortic valve dehiscence and free flow aortic regurgitation. An initial hemoculture grew out pleomorphic, gram-positive, non-motile, anaerobic to microaerophilic bacilli. A diagnosis of infective endocarditis was made using modified Duke criteria. He was treated with intravenous ampicillin and gentamicin. Four days after admission, he developed acute respiratory failure and succumbed to the disease. A pre-mortem hemoculture and post-mortem heart valve culture grew Arcanobacterium pyogenes. Septic thromboemboli involving the brain, kidneys, lungs and spleen were documented. The patient also had ischemic vasculopathy with focal spinal arteriolitis and bilateral demyelination of the cervical corticospinal tracts. There are three published reports of human A. pyogenes endocarditis in the literature. Neurological involvement with ischemic spinal vasculopathy and demyelination has not been reported. We report the first autopsy proven case of A. pyogenes infective endocarditis with ischemic spinal vasculopathy. We review the clinicopathologic features of systemic A. pyogenes infection.

A superior test for diagnosis of Clostridium difficile-associated diarrhea in resource-limited settings

In this prospective cohort study, we investigated the prevalence of Clostridium difficile-associated diarrhea (CDAD) in adult patients with nosocomial diarrhea by performing enzyme immunoassay (EIA) for detecting toxins A and B and polymerase chain reaction (PCR) for detecting the presence of the tcdB gene in stool samples. We determined the factors associated with CDAD, and the treatment outcome of CDAD from May 2010 to January 2011. A total of 175 stool samples were tested by EIA and PCR. In total, 26.9% patients tested positive for C. difficile: 12.6% by EIA and 24.0% by PCR. The kappa coefficient and total agreement of both the tests were 0.46 and 83.2%, respectively. Onset of diarrhea after antibiotic administration for 10 days or more (OR, 2.71; 95% CI, 1.14-6.44; P = 0.024) and leukocyte count >15,000 cells/mm(3) (OR, 3.12; 95% CI, 1.24-7.88; P = 0.016) were significantly associated with occurrence of CDAD. The non-response rate to CDAD treatment was 24.1%, and the all-cause mortality rate was 31.9% in the CDAD group as against 35.9% in the non-CDAD group (P = 0.721). In our study, the performance of direct PCR of stool samples for detecting tcdB was better, with the number of positive results for stool toxins A and B being twofold higher than that in the case of EIA. Patients who have diarrhea after receiving antibiotics for 10 days or more or those who have a leukocyte count of >15,000 cells/mm(3) should be investigated for CDAD.

Late and low compliance with hepatitis B serology screening among HIV-infected patients in a resource-limited setting: an issue to improve HIV care

Although hepatitis B serology screening has been recommended for HIV care, it has not been routinely performed. We aimed to assess compliance and timing of hepatitis B serology screening among HIV-infected patients in a resource-limited setting. A cross-sectional study was conducted in Thailand. Compliance, timing of hepatitis B serology screening, and factors associated with no HBsAg screening were determined. A total of 416 HIV-infected patients with 61% males were enrolled. Median (range) age at HIV diagnosis was 34 (16-75) years and 92% had heterosexual risk. Proportion of HBsAg screening and prevalence of positive HBsAg were 69.2% and 9.0%, respectively. There was no difference in the proportion of no HBsAg screening during the period 1990-2008 (p = 0.865). Proportion of anti-HBs and anti-HBc screening were 40.9% and 21.2%, respectively. HBsAg was screened before or on the day of anti-HIV testing in 9.1% and before antiretroviral therapy (ART) initiation in 27.2%. By Kaplan-Meier analysis, median time from anti-HIV testing to HBsAg screening was 55.9 (95% confidence interval [CI] 43.9, 68.3) months. By multivariate logistic regression, duration of HIV infection (odds ratio [OR] 1.14; 95% CI 1.07, 1.21), no anti-HBs screening (OR 1.65; 95% CI 1.4-2.63), and no anti-HCV screening (OR 2.60; 95% CI 1.62, 4.17) were associated with no HBsAg screening before ART initiation. In conclusion, compliance with hepatitis B serology screening was relatively low and late. Educational program regarding hepatitis B serology screening, identification of barriers, and interventions to eliminate these barriers in resource-limited settings are crucial to improve HIV care.