Comprehensive analysis of blood culture performed at nine university hospitals in Korea

Blood Culture Result Profile in Patients With Central Line-Associated Bloodstream Infection (CLABSI): A Single-Center Experience

Background Central line-associated bloodstream infection (CLABSI) is among the most common bloodstream infections in the university hospital and intensive care unit settings. This study evaluated the routine blood test findings and microbe profiles of bloodstream infection (BSI) by the presence and types of central vein (CV) access devices (CVADs). Methods A total of 878 inpatients at a university hospital who were clinically suspected for BSI and underwent blood culture (BC) testing between April 2020 and September 2020 were enrolled. Data regarding age at BC testing, sex, WBC count, serum C-reactive protein (CRP) level, BC test results, yielded microbes, and usage and types of CVADs were evaluated. Results The BC yields were detected in 173 patients (20%), suspected contaminating pathogens in 57 (6.5%), and 648 (74%) with a negative yield. The WBC count (p=0.0882) and CRP level (p=0.2753) did not significantly differ between the 173 patients with BSI and the 648 patients with negative BC yields. Among the 173 patients with BSI, 74 used CVADs and met the diagnosis of CLABSI; 48 had a CV catheter, 16 had CV access ports, and 10 had a peripherally inserted central catheter (PICC). Patients with CLABSI showed lower WBC counts (p=0.0082) and serum CRP levels (p=0.0024) compared to those with BSI who did not use CVADs. The most commonly yielded microbes in those with CV catheters, CV-ports, and PICC were Staphylococcus epidermidis (n=9; 19%), Staphylococcus aureus (n=6; 38%), and S. epidermidis (n=8; 80%), respectively. Among those with BSI who did not use CVADs, Escherichia coli (n=31; 31%) was the most common pathogen, followed by S. aureus (n=13; 13%). Conclusion Patients with CLABSI showed lower WBC counts and CRP levels than those with BSI who did not use CVADs. Staphylococcus epidermidis was among the most common microbes in CLABSI and accounted for the majority of yielded microbes in patients who used PICC.

Blood culture contamination rates at different level healthcare institutions in the Western Cape, South Africa

Sterile blood culture (BC) collection procedures are important to prevent the consequences of contamination, namely, prolonged patient hospitalisation, unnecessary antimicrobial exposure and an increase in hospital costs. Blood culture contamination rates were determined at different hospitals in the Cape Metropole over a 3-year period. Study findings showed that contaminated BCs have a financial impact on the healthcare system and contamination rates remain above accepted international standards, except in the presence of a phlebotomist team. High BC contamination rates might be reduced by the implementation of cost-effective educational intervention programmes, which reminds healthcare workers to collect BC samples aseptically.

Improvement of blood culture contamination rate, blood volume, and true positive rate after introducing a dedicated phlebotomy team

The introduction of dedicated phlebotomy teams certified for blood collection has been reported to be highly cost-effective by reducing contamination rates. However, data on their effects on blood volume and true positive rate are limited. Therefore, we investigated the effect of replacing interns with a phlebotomy team on blood culture results. We performed a 24-month retrospective, quasi-experimental study before and after the introduction of a phlebotomy team dedicated to collecting blood cultures in a 2700-bed tertiary-care hospital. The microbiology laboratory database was used to identify adult patients with positive blood culture results. During the study period, there were no changes in blood collection method, blood culture tubes, and the application of antiseptic measures. Blood volume was measured by the BACTEC™ FX system based on red blood cell metabolism. A total of 162,207 blood cultures from 23,563 patients were analyzed, comprising 78,673 blood cultures during the intern period and 83,534 during the phlebotomy team period. Blood volume increased from a mean of 2.1 ml in the intern period to a mean of 5.6 ml in the phlebotomy team period (p < 0.001). Introduction of the phlebotomy team also reduced contamination rate (0.27% vs. 0.45%, p < 0.001) and led to a higher true positive rate (5.87% vs. 5.01%, p < 0.05). The increased true positive rate associated with the phlebotomy team involved both gram-positive and gram-negative bacteria. The introduction of a dedicated phlebotomy team can increase blood volumes, reduce blood culture contamination rate, and increase true positive rate.

Soluble triggering receptor expressed on myeloid cells-1 as a useful biomarker for diagnosing ventilator-associated pneumonia after congenital cardiac surgery in children

The present study aimed to assess the usefulness of soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) in the diagnosis of ventilator-associated pneumonia (VAP) in paediatric patients with congenital heart disease (CHD) following cardiac surgery. The current prospective study enrolled 48 patients with congenital heart diseases who were suspected of having VAP; these patients were undergoing cardiac surgery between August 2016 and October 2017 in the Cardiac Intensive Care Unit of Shanghai Children's Medical Center (Shanghai, China). A total of 31 patients were diagnosed with VAP using a polymerase chain reaction (PCR) assay, while 17 patients without VAP were designated as the Non-VAP group. A bronchoscopy was performed and samples were collected for measurement on the day that VAP was diagnosed. The sTREM-1 levels were measured in bronchoalveolar lavage fluid (BALF) and exhaled ventilator condensate (EVC). BALF specimens were also sent to the microbiology laboratory for PCR assays and quantitative culturing. The positive detection rate of bacteria using the PCR assay and traditional culture was 64.6% (31/48) and 39.6% (19/48). sTREM-1 was significantly higher in the BALF (146.21 pg/ml vs. 118.06 pg/ml) and EVC (125.29 pg/ml vs. 120.48 pg/ml) of patients with VAP demonstrated compared with the patients without VAP. The findings suggest that the detection of sTREM-1 in BALF and EVC samples may be useful for the diagnosis of VAP following heart surgery in children.

PCR-reverse blot hybridization assay for screening and identification of pathogens in sepsis

Rapid and accurate identification of the pathogens involved in bloodstream infections is crucial for the prompt initiation of appropriate therapy, as this can decrease morbidity and mortality rates. A PCR-reverse blot hybridization assay for sepsis, the reverse blot hybridization assay (REBA) Sepsis-ID test, was developed; it uses pan-probes to distinguish Gram-positive and -negative bacteria and fungi. In addition, the assay was designed to identify bacteria and fungi using six genus-specific and 13 species-specific probes; it uses additional probes for antibiotic resistance genes, i.e., the mecA gene of methicillin-resistant Staphylococcus aureus (MRSA) and the vanA and vanB genes of vancomycin-resistant enterococci (VRE). The REBA Sepsis-ID test successfully identified clinical isolates and blood culture samples as containing Gram-positive bacteria, Gram-negative bacteria, or fungi. The results matched those obtained with conventional microbiological methods. For the REBA Sepsis-ID test, of the 115 blood culture samples tested, 47 (40.8%) and 49 (42.6%) samples were identified to the species and genus levels, respectively, and the remaining 19 samples (16.5%), which included five Gram-positive rods, were identified as Gram-positive bacteria, Gram-negative bacteria, or fungi. The antibiotic resistances of the MRSA and VRE strains were identified using both conventional microbiological methods and the REBA Sepsis-ID test. In conclusion, the REBA Sepsis-ID test developed for this study is a fast and reliable test for the identification of Gram-positive bacteria, Gram-negative bacteria, fungi, and antibiotic resistance genes (including mecA for MRSA and the vanA and vanB genes for VRE) in bloodstream infections.

Comparison of diagnostic tools with multiplex polymerase chain reaction for pediatric lower respiratory tract infection: a single center study

BACKGROUND/PURPOSE

Acute respiratory tract infections are a leading cause of morbidity and mortality in children worldwide. Most have a viral etiology, with pneumococcus as an important pathogen. This single-center study compared the use of conventional diagnostic tools and two multiplex polymerase chain reaction (PCR) examinations for determining pathogens in lower respiratory tract infections (LRTIs) among children aged <5 years.

METHODS

From July to October 2010, 45 patients aged 2 months to 60 months and diagnosed as having LRTIs were enrolled. Their nasopharyngeal aspirates were evaluated through viral culture and two multiplex PCR examinations. The patients' clinical course, symptoms, signs, and laboratory findings were recorded and analyzed.

RESULTS

Among the 45 patients, 38 (84.4%) had detectable pathogens. Conventional viral and blood cultures had 35.6% positive rate, which increased to 51.1% when the quick antigen tests (Influenza A+B test and respiratory syncytial virus) and urine pneumococcal antigen test were combined. The positive rate further increased to 84.4% when the two multiplex PCR methods were combined. Twelve patients had co-infection, including 10 detected by the multiplex PCR methods. The co-infection rate was 26.7% (12/45).

CONCLUSION

Most LRTIs in children have a viral etiology. Multiplex PCR tests are rapid assays that can increase the diagnostic yield rate and detect slow-growing viruses and can detect more pathogens than conventional viral culture to enable, thereby helping clinicians to provide appropriate and timely treatment.