Clinical outcomes and treatment necessity in patients with toxin-negative Clostridioides difficile stool samples.

PURPOSE: The clinical significance of negative toxin enzyme immunoassays (EIA) for Clostridioides difficile infections (CDIs) is unclear. Our study aimed to investigate the significance of toxin EIA-negative in the diagnosis and prognosis of CDI. METHODS: All stool specimens submitted for C. difficile toxin EIA testing were cultured to isolate C. difficile. In-house PCR for tcdA, tcdB, cdtA, and cdtB genes were performed using C. difficile isolates. Stool specimens were tested with C. difficile toxins A and B using EIA kit (RIDASCREEN Clostridium difficile toxin A/B, R-Biopharm AG, Darmstadt, Germany). Characteristics and subsequent CDI episodes of toxin EIA-negative and -positive patients were compared. RESULTS: Among 190 C. difficile PCR-positive patients, 83 (43.7%) were toxin EIA-negative. Multivariate analysis revealed independent associations toxin EIA-negative results and shorter hospital stays (OR = 0.98, 95% CI 0.96-0.99, p = 0.013) and less high-risk antibiotic exposure in the preceding month (OR = 0.38, 95% CI 0.16-0.94, p = 0.035). Toxin EIA-negative patients displayed a significantly lower white blood cell count rate (11.0 vs. 35.4%, p < 0.001). Among the 54 patients who were toxin EIA-negative and did not receive CDI treatment, three (5.6%) were diagnosed with CDI after 7-21 days without complication. CONCLUSION: Our study demonstrates that toxin EIA-negative patients had milder laboratory findings and no complications, despite not receiving treatment. Prolonged hospitalisation and exposure to high-risk antibiotics could potentially serve as markers for the development of toxin EIA-positive CDI.

Multifaceted Evaluation of Antibiotic Therapy as a Factor Associated with Candidemia in Non-Neutropenic Patients.

We aimed to evaluate various aspects of antibiotic therapy as factors associated with candidemia in non-neutropenic patients. A retrospective, matched, case-control study was conducted in two teaching hospitals. Patients with candidemia (cases) were compared to patients without candidemia (controls), matched by age, intensive care unit admission, duration of hospitalization, and type of surgery. Logistic regression analyses were performed to identify factors associated with candidemia. A total of 246 patients were included in the study. Of 123 candidemia patients, 36% had catheter-related bloodstream infections (CRBSIs). Independent factors in the whole population included immunosuppression (adjusted odds ratio [aOR] = 2.195; p = 0.036), total parenteral nutrition (aOR = 3.642; p < 0.001), and anti-methicillin-resistant S. aureus (MRSA) therapy for ≥11 days (aOR = 5.151; p = 0.004). The antibiotic factor in the non-CRBSI population was anti-pseudomonal beta-lactam treatment duration of ≥3 days (aOR = 5.260; p = 0.008). The antibiotic factors in the CRBSI population included anti-MRSA therapy for ≥11 days (aOR = 10.031; p = 0.019). Antimicrobial stewardship that reduces exposure to these antibacterial spectra could help prevent the development of candidemia.

Current and Emerging Knowledge in COVID-19.

COVID-19 has emerged as a pandemic leading to a global public health crisis of unprecedented morbidity. A comprehensive insight into the imaging of COVID-19 has enabled early diagnosis, stratification of disease severity, and identification of potential sequelae. The evolution of COVID-19 can be divided into early infectious, pulmonary, and hyperinflammatory phases. Clinical features, imaging features, and management are different among the three phases. In the early stage, peripheral ground-glass opacities are predominant CT findings, and therapy directly targeting SARS-CoV-2 is effective. In the later stage, organizing pneumonia or diffuse alveolar damage pattern are predominant CT findings and anti-inflammatory therapies are more beneficial. The risk of severe disease or hospitalization is lower in breakthrough or Omicron variant infection compared with nonimmunized or Delta variant infections. The protection rates of the fourth dose of mRNA vaccination were 34% and 67% against overall infection and hospitalizations for severe illness, respectively. After acute COVID-19 pneumonia, most residual CT abnormalities gradually decreased in extent, but they may remain as linear or multifocal reticular or cystic lesions. Advanced insights into the pathophysiologic and imaging features of COVID-19 along with vaccine benefits have improved patient care, but emerging knowledge of post-COVID-19 condition, or long COVID, also presents radiology with new challenges.

Clinical characteristics and manifestations in patients with hypermucoviscous Klebsiella pneumoniae bacteremia from extra-hepatobiliary tract infection.

PURPOSE: Hypermucoviscous strains of Klebsiella pneumoniae (KP) are associated with invasive liver abscess syndrome. However, little is known about the characteristics of this phenotype in non-hepatobiliary infections. In this study, we investigated the clinical characteristics of patients with hypermucoviscous Kp (hmvKp) bacteremia from non-hepatobiliary tract infection. METHODS: This retrospective cohort study was implemented at Samsung Changwon Hospital. From March 2018 to December 2019, adult patients (≥ 18 years) with KP bacteremia of the extra-hepatobiliary system were enrolled. Hypermucoviscosity was defined by the string test. Clinical characteristics and 30-day all-cause mortality between patients with hmvKp and non-hmvKp bacteremia were compared. RESULTS: Among 179 cases of non-hepatobiliary KP bacteremia, 67 (37.4%) and 112 (62.6%) isolates were classified as hmvKp and non-hmvKp, respectively. In the hmvKp group, metastatic infection (9.0 vs. 1.8%, P = 0.054) and purulent or necrotizing infection (31.3 vs. 9.8%, P < 0.001) were more frequently observed. Additionally, non-hmvKp had more frequent resistance to cefotaxime (11.9 vs. 38.4%, P < 0.001). Thirty-day all-cause mortality was similar in the hmvKp (41.8%) and non-hmvKp (39.3%) groups (P = 0.643). In multivariable analysis, septic shock (adjusted hazard ratio [aHR] = 3.05, 95% confidence interval [CI]: 1.22-7.63) and Pitt bacteremia score (aHR = 1.23 per 1 point, 95% CI 1.14-1.33) were associated with increased mortality in patients with Kp bacteremia, while urinary-tract infection (aHR = 0.38, 95% CI 0.18-0.76) was associated with decreased mortality. CONCLUSION: hmvKp was associated with less frequent drug resistance and metastatic-purulent presentation in non-hepatobiliary infection like in hepatobiliary infection. However, hmvKp was not associated with clinical outcomes.

Pneumocystis jirovecii Pneumonia in Patients with Solid Malignancies: A Retrospective Study in Two Hospitals.

Pneumocystis jirovecii pneumonia (PJP) is a rare opportunistic infection in patients with solid malignancies. This study aimed to examine the characteristics of patients with solid cancers and PJP. We retrospectively reviewed the medical records of patients with solid tumors and PJP over an 11-year period, enrolling a total of 47 patients (30-day survival group: n = 20, 30-day mortality group: n = 27). Only 34% of patients received ≥20 mg of prednisolone for ≥2 weeks, and the 30-day mortality rate was 57.4%. The 30-day survival group included more women and patients with colon cancer than the mortality group. Furthermore, absolute lymphocyte counts (ALCs) were decreased at PJP symptom onset, as compared with the values observed 1-3 months earlier. Increased oxygen demand and low ALCs after 5-7 days of PJP treatment were also related to poor prognosis. Due to the limitations of this retrospective study, further studies that adhere to the PJP criteria of the European Organization for Research and Treatment of Cancer and the Mycoses Study Group Education and Research Consortium will be needed to evaluate PJP in solid malignancies more clearly.

Impact of vancomycin use trend change due to the availability of alternative antibiotics on the prevalence of Staphylococcus aureus with reduced vancomycin susceptibility: a 14-year retrospective study.

BACKGROUND: We investigated the trend change in vancomycin-intermediate Staphylococcus aureus (VISA)/heterogeneous VISA (hVISA) prevalence among methicillin-resistant S. aureus (MRSA) bacteremia strains and antistaphylococcal antibiotic use together with mutation studies of vancomycin resistance-related gene loci to evaluate the impact of changes in antibiotic use after new antistaphylococcal antibiotics became available. METHODS: Among 850 healthcare-associated MRSA isolates from 2006 to 2019 at a tertiary hospital in South Korea, hVISA/VISA was determined by modified PAP/AUC analysis, and the identified hVISA/VISA strains were genotyped. Gene mutations at vraSR, graSR, walKR, and rpoB were studied by full-length sequencing. Antistaphylococcal antibiotic use in 2005-2018 was analyzed. RESULTS: Two VISA and 23 hVISA strains were identified. The prevalence rate ratio of hVISA/VISA carrying mutations at the two-component regulatory systems among MRSA was 0.668 (95% CI 0.531-0.841; P = 0.001), and the prevalence rate ratio of hVISA/VISA carrying rpoB gene mutations was 1.293 (95% CI 0.981-1.702; 174 P = 0.068). Annual vancomycin use density analyzed by days of therapy (DOT) per 1,000 patient-days did not decrease significantly, however the annual average length of time analyzed by the number of days vancomycin was administered for each case showed a significantly decreasing trend. CONCLUSIONS: During the 14-year period when the average length of vancomycin therapy decreased every year with the availability of alternative antibiotics, the prevalence of hVISA/VISA did not decrease significantly. This seems to be because the resistant strains carrying the rpoB mutations increased despite the decrease in the strains carrying the mutations at the two-component regulatory systems.

10-Year Retrospective Review of the Etiologies for Meningitis With Elevated Adenosine Deaminase in Cerebrospinal Fluid: Etiologies Other Than TB.

Purpose: An elevated adenosine deaminase (ADA) level in the cerebrospinal fluid (CSF) is considered a reliable marker of tuberculous meningitis (TBM). However, CSF-ADA levels can also be elevated in other diseases. We aimed to find the most common diagnosis of patients with elevated CSF-ADA levels for the last 10 years. Methods: We retrospectively investigated the diagnoses of all patients with elevated CSF-ADA (ADA ≥ 10 IU/L) levels between 2010 and 2019 at the Samsung Medical Center. Definite TBM was defined based on microbiological evidence. Clinical TBM was defined based on the brain imaging and response to the standard TB treatment. We compared the laboratory characteristics of the three most common diagnoses. Results: CSF-ADA levels were elevated in 137 (5.6%) of 2,600 patients. The most common diagnoses included hematologic malignancy (HM; n = 36, 26.2%), TBM (n = 26, 19.0%), and viral meningitis (VM; n = 25, 18.2%). CSF-ADA levels did not differ significantly between TBM [median (interquartile range (IQR)), 20.2 IU/L (13.8-29.3)] and HM [16.5 (12.8-24.0)]. However, CSF-ADA levels were lower in VM [14.0 (11.0-16.1)] than in TBM (p = 0.027). Lymphocyte-dominant pleocytosis was more common in VM [77.0% (70.8-81.5)] than in TBM [16.0 (3.0-51.0), p = 0.015] or HM [36.0 (10.0-72.0); p = 0.032]. Interestingly, the CSF characteristics of clinical TBM were similar to those of VM but not definite TBM. Conclusion: The most common diagnoses with elevated CSF-ADA levels were HM, followed by TBM and VM. Clinicians should carefully consider the differential diagnoses in patients with elevated CSF-ADA levels, especially those in the early stage of meningitis without microbiological evidence for TBM.

Clinical characteristics and the diagnostic role of molecular tests in musculoskeletal infections caused by nontuberculous Mycobacterium: a single-center experience.

PURPOSE: We retrospectively investigated NTM musculoskeletal infections to understand the clinical characteristics as well as the diagnostic performance of molecular tests as a useful supplementary test. METHODS: A retrospective cohort study was conducted from January 2016 to December 2019. Intraoperative specimens for culture and pathological analysis were obtained during surgery under sterile conditions. AdvanSure TB/NTM real-time PCR (LG Life Sciences, Seoul, Korea) and PCR-reverse blot hybridization assay (REBA, REBA Myco-ID; YD Diagnostics, Yongin, Republic of Korea) was performed directly from tissue specimens for the rapid and accurate identification of 20 mycobacterial species. RESULTS: A series of 24 patients was identified during the study period. Agricultural/aquatic exposure were predisposing factors in 9 patients, trauma in 4 patients, but no predisposing host factor was identified for 11 patients. Twenty-two patients presented with tenosynovitis and two with arthritis with substantial delays between initial presentation of symptoms and microbiologic diagnosis, with a median of 147 days (range 5-396 days). Pathologic tissue examination of musculoskeletal NTM infections was positive for chronic granulomatous inflammation in 18 cases. Fifteen were positive in the culture study, and nine were positive only in the molecular study using tissue specimens. All 6 M. ulcerans/M. marinum isolates were identified only by PCR. CONCLUSIONS: This study is an important reminder that NTM infections should be a part of the differential diagnosis in patients with chronic musculoskeletal infections refractory to regular treatment. Although molecular test cannot replace the conventional smear and culture methods, it can be used as a useful supplementary test especially in diagnosing M. marinum infection.

Correction: Candidemia Risk Prediction (CanDETEC) Model for Patients With Malignancy: Model Development and Validation in a Single-Center Retrospective Study.

[This corrects the article DOI: 10.2196/24651.].

Early Adverse Events between mRNA and Adenovirus-Vectored COVID-19 Vaccines in Healthcare Workers.

Mass vaccination campaigns are important to control the COVID-19 pandemic, however, adverse events (AEs) contribute to vaccine hesitancy. To investigate and compare early AEs between the BNT162b2 mRNA and AZD1222 adenovirus-vectored vaccines, recipients completed daily surveys about local and systemic reactions for 7 days after each dose, respectively. A total of 80 and 1440 healthcare workers received two doses of BNT162b2 and a first dose of AZD1222 vaccines. Any AEs were reported by 52.5% of recipients after the first dose of BNT162b2, by 76.2% after the second dose of BNT162b2, and by 90.9% after the first dose of AZD1222 (p < 0.001). Younger vaccinees had more AEs after the second dose of BNT162b2 and first dose of AZD1222. Sex based differences were only observed in the AZD1222 recipient group. No incidence of anaphylaxis or neurologic AEs were observed. In conclusion, early AEs were mostly mild to moderate in severity and generally transient in both BNT162b2 and AZD1222 groups. Sufficient explanation of the expected AEs of the vaccine would be helpful for wider vaccination.

Candidemia Risk Prediction (CanDETEC) Model for Patients With Malignancy: Model Development and Validation in a Single-Center Retrospective Study.

BACKGROUND: Appropriate empirical treatment for candidemia is associated with reduced mortality; however, the timely diagnosis of candidemia in patients with sepsis remains poor. OBJECTIVE: We aimed to use machine learning algorithms to develop and validate a candidemia prediction model for patients with cancer. METHODS: We conducted a single-center retrospective study using the cancer registry of a tertiary academic hospital. Adult patients diagnosed with malignancies between January 2010 and December 2018 were included. Our study outcome was the prediction of candidemia events. A stratified undersampling method was used to extract control data for algorithm learning. Multiple models were developed-a combination of 4 variable groups and 5 algorithms (auto-machine learning, deep neural network, gradient boosting, logistic regression, and random forest). The model with the largest area under the receiver operating characteristic curve (AUROC) was selected as the Candida detection (CanDETEC) model after comparing its performance indexes with those of the Candida Score Model. RESULTS: From a total of 273,380 blood cultures from 186,404 registered patients with cancer, we extracted 501 records of candidemia events and 2000 records as control data. Performance among the different models varied (AUROC 0.771- 0.889), with all models demonstrating superior performance to that of the Candida Score (AUROC 0.677). The random forest model performed the best (AUROC 0.889, 95% CI 0.888-0.889); therefore, it was selected as the CanDETEC model. CONCLUSIONS: The CanDETEC model predicted candidemia in patients with cancer with high discriminative power. This algorithm could be used for the timely diagnosis and appropriate empirical treatment of candidemia.

Sequence type 17 is a predictor of subsequent bacteremia in vancomycin-resistant Enterococcus faecium-colonized patients: a retrospective cohort study.

BACKGROUND: Sequence type (ST) 17 vancomycin-resistant Enterococcus faecium (VREF) is frequently isolated in nosocomial settings. The aim of this study was to identify whether ST17 contributes to subsequent bacteremia more often than other STs among hospitalized patients carrying VREF. METHODS: A retrospective cohort study was conducted in patients carrying ST17 VREF and those with non-ST17 VREF. Rectal screening according to hospital policy was used to identify patients with VREF. Subsequent VREF bacteremia events within a year of detection of colonization were recorded. Cox regression analysis was used to adjust the covariates involved in determining the association between ST17 and subsequent bacteremia events. RESULTS: The cohorts comprised 52 patients with ST17 and 169 patients with non-ST17 VREF. One-year VREF bacteremia-free rates were 85.9% and 90.2%, respectively. In multivariate analysis, ST17 was associated with subsequent bacteremia at an adjusted hazard risk (aHR) of 4.02 (95% confidence interval [CI], 1.32-12.29). Liver transplantation (aHR, 40.08; 95% CI, 4.87-329.76) and hematologic malignancy (aHR, 20.97; 95% CI, 4.87-87.82) were also significant. All cases of subsequent bacteremia in ST17 VREF carriers were caused by ST17; however, subsequent bacteremia in non-ST17 carriers was often caused by ST17 or another ST variant. CONCLUSIONS: A specific genotype, ST17 is a predictor of subsequent bacteremia in hospitalized patients carrying VREF. Patients with a hematologic malignancy and those receiving a liver transplant are also at high risk. More targeted strategies may be needed to prevent VREF infection in hospitals.

Therapeutic Drug Level Monitoring of Teicoplanin in Korean Pediatric Patients with Normal versus Impaired Renal Function.

BACKGROUND: Teicoplanin is used to treat serious gram-positive infections. Optimal teicoplanin trough levels are considered to be ≥ 10 µg/mL. Despite its wide use in various clinical settings, data on teicoplanin trough level in pediatric patients are limited. Therefore, the aim of this study was to investigate the therapeutic drug level monitoring of teicoplanin in Korean pediatric patients, including those with impaired renal function. METHODS: A retrospective study was performed in pediatric patients (age ≤ 18 years old) who received teicoplanin from September 2014 to April 2018. The regimen included a loading dose of 10 mg/kg/dose at 12 hours' interval three times in a row, and a maintenance dose of 10 mg/kg/dose commenced at 24 hours of interval after the loading dose, with a maximum of 400 mg/dose, respectively. The first therapeutic drug levels were measured. Distribution and characteristics of trough levels in patients with decreased renal function and those with bacteremia were also assessed. RESULTS: A total of 187 trough levels were collected from 143 patients. Hematologic and oncologic diseases were the most common underlying diseases (83.2%, n = 119). One hundred eighty trough levels were first measured, and their median value was 16.2 µg/mL (range, 2.3-100 µg/mL) and the median interval between initial teicoplanin injection and 1st trough level was 96.5 hours (range 47.6-179.3 hours). Lower steady-state levels were observed in younger age group (median, 13.5 vs. 18.0 µg/mL, P = 0.038). Median trough levels were higher in patients with decreased renal functions (P < 0.001). In addition, among eight with gram-positive bacteremia, seven of them had a favorable outcome. CONCLUSION: This study provides additive information on trough level monitoring of teicoplanin in children with impaired renal function and treatment effect in patients with gram-positive bacteremia. Careful monitoring for steady state trough levels of teicoplanin is warranted.

Antifungal prophylaxis with posaconazole tablet and oral suspension in patients with haematologic malignancy: Therapeutic drug monitoring, efficacy and risk factors for the suboptimal level.

BACKGROUND: Posaconazole is used to prevent invasive fungal infections (IFIs) in patients with haematologic malignancy. In this study, we compared plasma posaconazole concentrations (PPCs) and the incidence of breakthrough IFIs between patients with haematologic malignancy receiving posaconazole oral suspension vs tablet. METHODS: We retrospectively collected data on adult patients with haematologic malignancies who received posaconazole prophylaxis during chemotherapy from April 2014 through May 2018. A total of 242 cases with PPCs, 88 in the oral suspension group and 154 in the tablet group, were included in this study. RESULTS: Patients receiving tablets achieved a significantly higher mean PPC than did those on oral suspension (1.631 ± 0.878 µg/mL in the tablet group vs. 0.879 ± 0.585 µg/mL in the oral suspension group). One hundred and thirty-seven of 154 patients (89.0%) receiving tablets had PPCs of 0.7 µg/mL or more, while only 41 of 88 patients (46.6%) receiving oral suspension attained an optimal level (P < .001). The incidence of breakthrough IFIs was significantly higher in the oral suspension group compared with in the tablet group (14.8% of oral suspension vs. 4.5% of tablet; P = .005). In the analysis including patients receiving posaconazole tablets, hypoalbuminemia (< 3.5 g/dL) was found to be a risk factor associated with suboptimal levels (odds ratio: 8.872; 95% confidence interval: 3.011 - 26.141; P < .001). CONCLUSIONS: Suboptimal PPCs in the tablet group were less common than those in the oral suspension group. Therapeutic drug monitoring may be still necessary even in patients receiving posaconazole tablets, especially in those with hypoalbuminemia.

Evaluation of a Carbapenem-Saving Strategy Using Empirical Combination Regimen of Piperacillin-Tazobactam and Amikacin in Hemato-Oncology Patients.

We implemented a carbapenem-saving strategy in hemato-oncology patients from 2013, using an empirical combination of piperacillin-tazobactam and amikacin for high-risk hemato-oncology patients with febrile neutropenia, who remain hemodynamically unstable > 72 hours despite initial cefepime treatment. All-cause mortality was not different between the two periods (6.54 and 6.57 deaths per 1,000 person-day, P = 0.926). Group 2 carbapenem use significantly decreased after strategy implementation (78.43 vs. 67.43 monthly days of therapy, P = 0.018), while carbapenem-resistant gram-negative bacilli did not show meaningful changes during the study period. Our carbapenem-saving strategy could effectively suppress carbapenem use without an increase of overall mortality.

Pathogenic significance of hemorrhagic pneumonia in hematologic malignancy patients with Stenotrophomonas maltophilia bacteremia: clinical and microbiological analysis.

Hemorrhagic pneumonia (HP) is known as the clinical manifestation of Stenotrophomonas maltophilia infection, while catheter-related blood stream infection (CRBSI) is the common clinical presentation of S. maltophilia bacteremia (SMB). The purpose of this study is to evaluate the risk factors for mortality in hematologic malignancy patients with SMB and to analyze clinical and microbiological characteristics of HP associated with SMB and CRBSI. SMB cases of patients with a hematologic malignancy were collected from 2006 through 2016. The overall 30-day mortality rate and mortality risk factors were assessed. The expression of major virulence-associated genes from S. maltophilia isolates, which included genes encoding type-1 fimbriae (smf-1), proteases (StmPr1 and StmPr2), and esterase (Smlt3773), from the blood of patients with HP and CRBSI was investigated. The phenotypic and genotypic traits were also compared. A total of 118 cases of SMB were included. The overall 30-day mortality rate was 61.0%. A multivariable analysis showed that HP was the most important risk factor for mortality (adjusted OR = 106.41; 95% CI = 5.18-2184.55). Although no statistical significance was observed in microbiological analysis, isolates from HP have a trend toward a higher protease activity (93.8% vs. 73.3%, P = 0.172). Clinical analysis showed that thrombocytopenia (P = 0.037) and prolonged neutropenia (P = 0.043) were significant factors associated with HP. Our data, which includes hematologic malignancy patients with SMB, suggest that HP is the significant risk factor for mortality and that the unique characteristics of patients and microbes contribute to the pathogenesis.

Validation of semiautomated surgical site infection surveillance using electronic screening algorithms in 38 surgery categories.

OBJECTIVE: To verify the validity of a semiautomated surgical site infection (SSI) surveillance system using electronic screening algorithms in 38 categories of surgery. DESIGN: A cohort study for validation of semiautomated SSI surveillance system using screening algorithms. SETTING: A 1,989-bed tertiary-care referral center in Seoul, Republic of Korea. METHODS: A dataset of 40,516 surgical procedures in 38 categories stored in the conventional SSI surveillance registry at the Samsung Medical Center between January 2013 and December 2014 was used as the reference standard. In the semiautomated surveillance system, electronic screening algorithms flagged cases meeting at least 1 of 3 criteria: antibiotic prescription, microbial culture, and infectious disease consultation. Flagged cases were audited by infection preventionists. Analyses of sensitivity, specificity, and positive predictive value (PPV) were conducted for the semiautomated surveillance system, and its effect on reducing the workload for chart review was evaluated. RESULTS: A total of 575 SSI events (1·42%) were identified by conventional SSI surveillance. The sensitivity of the semiautomated SSI surveillance was 96·7%, and the PPV of the screening algorithms alone was 4·1%. Semiautomated SSI surveillance reduced the chart review workload of the infection preventionists from 1,283 to 482 person hours per year (a 62·4% decrease). CONCLUSIONS: Compared to conventional surveillance, semiautomated surveillance using electronic screening algorithms followed by chart review of selected cases can provide high-validity surveillance results and can significantly reduce the workload of infection preventionists.

Clinical predictors of Stenotrophomonas maltophilia bacteremia in adult patients with hematologic malignancy.

Stenotrophomonas maltophilia (SM) has emerged as an important nosocomial pathogen with high morbidity and mortality. Because of its unique antimicrobial susceptibility pattern, appropriate antimicrobial therapy for SM bacteremia is still challenging, especially in immunocompromised patients. The present study was performed to assess clinical predictors of SM bacteremia in adult patients with hematologic malignancy. From 2006 through 2016, a case-control study was performed at a tertiary-care hospital. Case patients were defined as SM bacteremia in patients with hematologic malignancy. Date- and location-matched controls were selected from among patients with gram-negative bacteremia (GNB) other than SM. A total of 118 cases of SM bacteremia were identified and compared to 118 controls. While pneumonia was the most common source of SM bacteremia, centralline-associated infection was most common in the controls. The overall 30-day mortality rate of cases with SM bacteremia was significantly higher than that of the controls (61.0 and 32.2%, respectively; P < 0.001). A multivariable analysis showed that polymicrobial infection, previous SM isolation, the number of antibiotics previously used ≥ 3, and breakthrough bacteremia during carbapenem therapy were significantly associated with SM bacteremia (all P < 0.01). Previous use of trimethoprim/sulfamethoxazole (TMP/SMX) was negatively association with SM bacteremia (P = 0.002). Our data suggest that SM is becoming a significant pathogen in patients with hematologic malignancy. Several clinical predictors of SM bacteremia can be used for appropriate antimicrobial therapy in hematologic patients with suspected GNB.

Atypical presentations of MERS-CoV infection in immunocompromised hosts.

During the 2015 Korean MERS outbreak, we experienced atypical presentations of MERS-CoV infections in three immunocompromised hosts that warranted exceptional management. Case 1 showed delayed symptom development after a four-day asymptomatic period, Case 2 experienced a 20-day incubation period, and Case 3 exhibited persistent viral shedding without clinical deterioration. Recognizing these exceptions is extremely important in the management of MERS-CoV-exposed or -infected patients and for control of potential MERS outbreaks.