Clinical Characteristics and Risk Factors for Mortality in Critical Coronavirus Disease 2019 Patients 50 Years of Age or Younger During the Delta Wave: Comparison With Patients > 50 Years in Korea

Background@#Numerous patients around the globe are dying from coronavirus disease 2019 (COVID-19). While age is a known risk factor, risk analysis in the young generation is lacking. The present study aimed to evaluate the clinical features and mortality risk factors in younger patients (≤ 50 years) with a critical case of COVID-19 in comparison with those among older patients (> 50 years) in Korea. @*Methods@#We analyzed the data of adult patients only in critical condition (requiring high flow nasal cannula oxygen therapy or higher respiratory support) hospitalized with PCR-confirmed COVID-19 at 11 hospitals in Korea from July 1, 2021 to November 30, 2021 when the delta variant was a dominant strain. Patients’ electronic medical records were reviewed to identify clinical characteristics. @*Results@#During the study period, 448 patients were enrolled. One hundred and forty-two were aged 50 years or younger (the younger group), while 306 were above 50 years of age (the older group). The most common pre-existing conditions in the younger group were diabetes mellitus and hypertension, and 69.7% of the patients had a body mass index (BMI) > 25 kg/m 2 .Of 142 younger patients, 31 of 142 patients (21.8%, 19 women) did not have these pre-existing conditions. The overall case fatality rate among severity cases was 21.0%, and it differed according to age: 5.6% (n = 8/142) in the younger group, 28.1% in the older group, and 38% in the ≥ 65 years group. Age (odds ratio [OR], 7.902; 95% confidence interval [CI], 2.754–18.181), mechanical ventilation therapy (OR, 17.233; 95% CI, 8.439–35.192), highest creatinine > 1.5 mg/dL (OR, 17.631; 95% CI, 8.321–37.357), and combined blood stream infection (OR, 7.092;95% CI, 1.061–18.181) were identified as independent predictors of mortality in total patients.Similar patterns were observed in age-specific analyses, but most results were statistically insignificant in multivariate analysis due to the low number of deaths in the younger group.The full vaccination rate was very low among study population (13.6%), and only three patients were fully vaccinated, with none of the patients who died having been fully vaccinated in the younger group. Seven of eight patients who died had a pre-existing condition or were obese (BMI > 25 kg/m 2 ), and the one remaining patient died from a secondary infection. @*Conclusion@#About 22% of the patients in the young critical group did not have an underlying disease or obesity, but the rate of obesity (BMI > 25 kg/m2 ) was high, with a fatality rate of 5.6%. The full vaccination rate was extremely low compared to the general population of the same age group, showing that non-vaccination has a grave impact on the progression of COVID-19 to a critical condition. The findings of this study highlight the need for measures to prevent critical progression of COVID-19, such as vaccinations and targeting young adults especially having risk factors.

Experimental and Mathematical Optimization of a Pooling Test for Detection of SARS-CoV-2 in a Population with Low Viral Load / 감염과화학요법

Background@#A pooling test is a useful tool for mass screening of coronavirus disease 2019 (COVID-19) in the pandemic era. We aimed to optimize a simple two-step pooling test by estimating the optimal pool size using experimental and mathematical validation. @*Materials and Methods@#Experimental pools were created by mixing one positive respiratory sample with various numbers of negative samples. We selected positive samples with cycle threshold (Ct) values greater than 32 to validate the efficiency of the pooling test assuming a high likelihood of false-negative results due to low viral loads. The positivities of the experimental pools were investigated with a single reverse-transcription polymerase chain reaction (RT-PCR) using the U-TOP™ COVID-19 Detection Kit Plus (Seasun Biomaterials, Daejeon, Korea). We used the Dorfman equation to calculate the optimal size of a pooling test mathematically. @*Results@#Viral RNA could be detected in a pool with a size up to 11, even if the Ct value of a positive sample was about 35. The Dorfman equation showed that the optimal number of samples in a pool was 11 when the prevalence was assumed to be 0.66% based on the test positivity in Daejeon, Korea from April 1, 2020 to November 10, 2020. The efficiency of the pooling test was 6.2, which can save 83.9 of 100 individual tests. @*Conclusion@#Eleven samples in a pool were validated optimal experimentally assuming a prevalence of 0.66%. The pool size needs modification as the pandemic progresses; thus, the prevalence should be carefully estimated before pooling tests are conducted.

Experimental and Mathematical Optimization of a Pooling Test for Detection of SARS-CoV-2 in a Population with Low Viral Load / 감염과화학요법

Background@#A pooling test is a useful tool for mass screening of coronavirus disease 2019 (COVID-19) in the pandemic era. We aimed to optimize a simple two-step pooling test by estimating the optimal pool size using experimental and mathematical validation. @*Materials and Methods@#Experimental pools were created by mixing one positive respiratory sample with various numbers of negative samples. We selected positive samples with cycle threshold (Ct) values greater than 32 to validate the efficiency of the pooling test assuming a high likelihood of false-negative results due to low viral loads. The positivities of the experimental pools were investigated with a single reverse-transcription polymerase chain reaction (RT-PCR) using the U-TOP™ COVID-19 Detection Kit Plus (Seasun Biomaterials, Daejeon, Korea). We used the Dorfman equation to calculate the optimal size of a pooling test mathematically. @*Results@#Viral RNA could be detected in a pool with a size up to 11, even if the Ct value of a positive sample was about 35. The Dorfman equation showed that the optimal number of samples in a pool was 11 when the prevalence was assumed to be 0.66% based on the test positivity in Daejeon, Korea from April 1, 2020 to November 10, 2020. The efficiency of the pooling test was 6.2, which can save 83.9 of 100 individual tests. @*Conclusion@#Eleven samples in a pool were validated optimal experimentally assuming a prevalence of 0.66%. The pool size needs modification as the pandemic progresses; thus, the prevalence should be carefully estimated before pooling tests are conducted.

Higher Risk for All-cause Mortality of Staphylococcus aureus Bacteremia in Patients with Non-Dialysis Dependent Chronic Kidney Disease / 감염과화학요법

Background@#Staphylococcus aureus bacteremia (SAB) is a common and serious infection with a high mortality. Patients with chronic kidney disease (CKD) are vulnerable to SAB, but there have been few studies performed on the clinical characteristics and outcomes of SAB in CKD patients stratified by dialysis. We aimed to estimate the all-cause mortality and identify its predictors in patients with CKD. @*Materials and Methods@#We conducted a retrospective study on the patients with SAB hospitalized in a tertiary care center in Korea between March 2014 and December 2018.Kaplan-Meier analysis was performed to compare all-cause mortality following SAB among patients with non-dialysis dependent CKD (ND-CKD), those receiving dialysis, and those without CKD (non-CKD). The predictors of mortality among CKD patients were analyzed by Cox proportional hazards regression. @*Results@#As a total, 278 SAB of 43 ND-CKD (31 males), 58 dialysis (39 males), and 177 nonCKD (112 males) patients were included. The 30-day mortality was 39.5% in ND-CKD, 27.6% in dialysis, and 7.9% in non-CKD patients. The hazard ratio of all-cause mortality following SAB in ND-CKD was 2.335 (95% confidence interval, 1.203 – 4.531; P = 0.003), compared to non-CKD patients. For methicillin-resistant S. aureus bacteremia (MRSAB), the hazard ratio of all-cause mortality in ND-CKD was 2.628 (95% CI, 1.074 – 6.435; P = 0.011), compared to dialysis patients. Appropriate antibiotics <48 h was independently related to improved survival following SAB among ND-CKD (adjusted HR, 0.304; 95% CI, 0,108 – 0.857; P = 0.024) and dialysis (adjusted HR, 0.323; 95% CI, 0,116 – 0.897; P = 0.030) patients. @*Conclusion@#ND-CKD patients demonstrated poor outcome following SAB and administration of appropriate antibiotics within 48 h could reduce the risk for mortality.

Acute Kidney Injury and Kidney Damage in COVID-19 Patients

Background@#Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This disease, which is quickly spreading worldwide, has high potential for infection and causes rapid progression of lung lesions, resulting in a high mortality rate. This study aimed to investigate the effects of SARS-CoV-2 infection on renal function in patients with COVID-19. @*Methods@#From February 21 to April 24, 2020, 66 patients diagnosed with COVID-19 at Chungnam National University Hospital were analyzed; all patients underwent routine urinalysis and were tested for serum creatinine, urine protein to creatinine ratio (PCR), and urine albumin to creatinine ratio (ACR). @*Results@#Acute kidney injury (AKI) occurred in 3 (4.5%) of the 66 patients, and 1 patient with AKI stage 3 underwent hemodialysis. Upon follow-up, all 3 patients recovered normal renal function. Compared with patients with mild COVID-19, AKI (n = 3) occurred in patients with severe COVID-19, of whom both urine PCR and ACR were markedly increased. @*Conclusion@#The incidence of AKI was not high in COVID-19 patients. The lower mortality rate in SARS-CoV-2 infection compared with previous Middle East respiratory syndrome and SARS-CoV infections is thought to be associated with a low incidence of dysfunction in organs other than the lungs.

Subdural Empyema Caused by Nontyphoidal Salmonella in a Patient with a Previous Evacuation of Subdural Hematoma / 대한내과학회지

Nontyphoidal Salmonella infection often results in acute gastroenteritis, but extraintestinal infection presenting as a subdural empyema is unusual. We report a case of a 67-year-old man diagnosed with a subdural empyema caused by Salmonella group B that developed after evacuation of a subdural hematoma. To our knowledge, this is the first such case report in Korea.

Outbreaks of Middle East Respiratory Syndrome in Two Hospitals Initiated by a Single Patient in Daejeon, South Korea / 감염과화학요법

BACKGROUND: A Middle East Respiratory Syndrome coronavirus (MERS-CoV) outbreak in South Korea in 2015 started by a single imported case and was amplified by intra- and inter-hospital transmission. We describe two hospital outbreaks of MERS-CoV infection in Daejeon caused by a single patient who was infected by the first Korean case of MERS. MATERIALS AND METHODS: Demographic and clinical information involving MERS cases in the Daejeon cluster were retrospectively collected and potential contacts and exposures were assessed. The incubation periods and serial intervals were estimated. Viral RNAs were extracted from respiratory tract samples obtained from the index case, four secondary cases and one tertiary case from each hospital. The partial S2 domain of the MERS-CoV spike was sequenced. RESULTS: In Daejeon, a MERS patient (the index case) was hospitalized at Hospital A in the first week of illness and was transferred to Hospital B because of pneumonia progression in the second week of illness, where he received a bronchoscopic examination and nebulizer therapy. A total of 23 secondary cases (10 in Hospital A and 13 in Hospital B) were detected among patients and caregivers who stayed on the same ward with the index case. There were no secondary cases among healthcare workers. Among close hospital contacts, the secondary attack rate was 15.8% (12/76) in Hospital A and 14.3% (10/70) in Hospital B. However, considering the exposure duration, the incidence rate was higher in Hospital B (7.7/100 exposure-days) than Hospital A (3.4/100 exposure-days). In Hospital B, the median incubation period was shorter (4.6 days vs. 10.8 days), the median time to pneumonia development was faster (3 days vs. 6 days) and mortality was higher (70% vs. 30.8%) than in Hospital A. MERS-CoV isolates from 11 cases formed a single monophyletic clade, with the closest similarity to strains from Riyadh. CONCLUSION: Exposure to the MERS case in the late stage (2nd week) of diseases appeared to increase the risk of transmission and was associated with shorter incubation periods and rapid disease progression among those infected. Early detection and isolation of cases is critical in preventing the spread of MERS in the hospital and decreasing the disease severity among those infected.

Controlling endemic multidrug-resistant Acinetobacter baumannii in Intensive Care Units using antimicrobial stewardship and infection control

BACKGROUND/AIMS: Nosocomial infections caused by multidrug-resistant (MDR) Acinetobacter baumannii have become public-health problem. However, few studies have evaluated the control of endemic MDR A. baumannii in Intensive Care Units (ICUs). Therefore, we investigated the effectiveness of antimicrobial stewardship and comprehensive intensified infection control measures for controlling endemic MDR A. baumannii in ICUs at a tertiary care center. METHODS: Carbapenem use was strictly restricted through antimicrobial stewardship. Environmental cleaning and disinfection was performed at least 3 times per day in addition to basic infection control measures. Isolation using plastic curtains and contact precautions were applied to patients who were colonized or infected with MDR A. baumannii. The outcome was measured as the incidence density rate of hospital-onset MDR A. baumannii among patients in the ICUs. RESULTS: The incidence density rate of hospital-onset MDR A. baumannii decreased from 22.82 cases per 1,000 patient-days to 2.68 cases per 1,000 patient-days after the interventions were implemented (odds ratio, 0.12; 95% confidence interval, 0.03 to 0.4; p < 0.001). The mean monthly use of carbapenems also decreased from 134.99 +/- 82.26 defined daily doses per 1,000 patient-days to 94.85 +/- 50.98 defined daily doses per 1,000 patient-days (p = 0.016). CONCLUSIONS: Concomitant implementation of strict antimicrobial stewardship and comprehensive infection control measures effectively controlled endemic MDR A. baumannii in our ICUs within 1 year.

Vertebral Osteomyelitis due to Mycobacterium intracellulare in an Immunocompetent Elderly Patient After Vertebroplasty

Mycobacterium avium complex (MAC) comprises M. intracellulare and M. avium. MAC usually causes pulmonary diseases in individuals with intact immunity, disseminated disease in patients with acquired immunodeficiency syndrome, and cervical lymphadenitis. It can also cause cutaneous disease, but musculoskeletal infection is rare. Herein, we present a case of vertebral osteomyelitis due to M. intracellulare in an elderly immunocompetent patient who underwent vertebroplasty. The patient was successfully treated with antimycobacterial drugs without surgical intervention. MAC should be considered as a causative pathogen of vertebral osteomyelitis when the patient has a history of vertebroplasty.

Benign Lymphoepithelial Cyst of the Parotid Gland as an Initial Manifestation of Human Immunodeficiency Virus Infection / 대한내과학회지

Benign lymphoepithelial cysts are rare, and are associated with swelling of the salivary glands (usually the parotid gland). The cytopathological features include lymphoid hyperplasia with an epithelial component, exhibiting cystic and proliferative changes. Development of a benign lymphoepithelial cyst commonly precedes acquisition of acquired immunodeficiency syndrome, but may also be the initial clinical manifestation of human immunodeficiency virus (HIV) infection. A 43 year-old male presented with a slowly growing multilocular cystic mass in his right cheek. Computed tomography of the neck revealed a well-circumscribed cystic lesion in the bilateral parotid glands. A provisional diagnosis of a benign lymphoepithelial cyst associated with HIV infection was made, and Western blotting confirmed the HIV infection. Three months after initiation of antiretroviral therapy, the parotid swelling was completely resolved. We report this case to suggest that clinicians should consider the possibility of HIV infection when patients present with benign lymphoepithelial cysts of the parotid gland.

Septic Knee Arthritis Caused by Staphylococcus lugdunensis After Intraarticular Injection Therapy

Staphylococcus lugdunensis is a coagulase-negative staphylococcus. However, it causes various clinically important human infections and behaves similar to Staphylococcus aureus. S. lugdunensis reportedly causes infective endocarditis, skin and soft tissue infection, bone and joint infection, septicemia, endarteritis, urinary tract infection, ocular infection, and peritonitis. There are no reports of septic arthritis by this organism in Korea. We presented a case of septic arthritis due to S. lugdunensis in an elderly patient with diabetes mellitus after an intra-articular injection.

Vertebral Osteomyelitis caused by Burkholderia cepacia in an Immunocompetent Elderly Patient After Acupuncture

Burkholderia cepacia is an important nosocomial pathogen in hospitalized patients, particularly those with prior antimicrobial therapy. B. cepacia causes various clinically significant infections such as bacteremia, pneumonia, and urinary tract and surgical site infections. However, osteomyelitis caused by B. cepacia is very rare. We present a case of B. cepacia vertebral osteomyelitis with review of the literature.

A Case of Vertebral Osteomyelitis Caused by Serratia grimesii in a Patient without Predisposing Factors / 대한내과학회지

Vertebral osteomyelitis or paraspinal abscess caused by Serratia species is rare and has been reported only in certain groups of people, such as intravenous drug users, immunocompromised hosts, and patients who have undergone invasive procedures. However, we report here that Serratia was recovered from a patient with vertebral osteomyelitis and epidural abscess without predisposing factors. The organism was initially identified as Serratia liquefaciens by a Vitek II-based assessment. It was finally identified as Serratia grimesii by 16S rRNA gene sequence analysis. We present the first case of vertebral osteomyelitis caused by S. grimesii in a patient without risk factors and who was managed successfully.

Respiratory Virus Detection Rate in Patients with Severe or Atypical Community-acquired Pneumonia / 결핵및호흡기질환

BACKGROUND: Community-acquired pneumonia (CAP) is an important cause of morbidity and mortality throughout the world in all age groups. Viral causes of CAP are less well characterized than bacterial causes. We analyzed the characteristics of hospitalized patients with CAP who had a viral pathogen detected by multiplex polymerase chain reaction (PCR). METHODS: Multiplex real-time PCR was performed for respiratory viruses in samples collected from 520 adults who developed CAP at Chungnam National University Hospital. Clinical, laboratory, and radiological features at presentation as well as other epidemiological data were analyzed. RESULTS: Of 520 patients with CAP, a viral pathogen was detected in 60 (11.5%), and influenza A was the most common. The virus detection rate in patients with CAP was highest in November. Two or more pathogens were detected in 13 (21.7%) patients. Seven patients had severe disease and were administered in the intensive care unit. Most patients (49/60, 81.7%) had comorbidities. However, nine (15%) patients had no comorbidities, and their age was <60 years. The ground glass opacity pattern was the most common radiological feature. Seven (11.7%) patients died from CAP. CONCLUSION: Viral pathogens are commonly detected in patients with CAP, and a respiratory virus may be associated with the severity and outcome of pneumonia. Careful attention should be paid to the viral etiology in adult patients with CAP.

Community-Onset Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Osteomyelitis of the Pubic Symphysis / 감염과화학요법

Osteomyelitis of the pubic symphysis or pubic osteomyelitis is a rare disease entity. Predisposing factors include trauma, pelvic or urologic surgery, intravenous drug abuse, pelvic malignancy, parturition and cardiac catheterization. Pathogens vary depending on the risk factors. The most frequent causative organism is Staphylococcus aureus . Gram-negative bacteria such as Pseudomonas aeruginosa and Escherichia coli are also common pathogens. However, pubic osteomyelitis due to community-onset extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli has not previously been described. We present a patient with pubic osteomyelitis caused by ESBL-producing Escherichia coli without known predisposing factors except for diabetes.