Blood Culture Techniques: Increasing Yields and Reducing Contamination (original) (raw)
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International Journal of Medical Research and Review
Background: An important but controversial subject is the number of blood culture sets required for the diagnosis of blood stream infection (BSI) and also the use of appropriate antibiotics to treat bacteremia. This paper focuses on the need of two blood culture set in comparison to one blood culture in the diagnosis of bacteraemia. Methods: First and second sets were collected aseptically from two different sites at an interval of about one hour from all clinically suspect patients of bacteremia. The samples were processed in Bact/ALERT3D system and further identified in VITEK 2 compact. Results: Second blood culture set yielded higher rates of positive cultures (63%) than first set (37%). The common bacterial isolates were Coagulase negative Staphylococcus (CoNS) 29 (28%), followed by Staphylococcus aureus 20 (20%), Escherichia coli 13 (13%) and Klebsiella pneumonia 11(11%). Methicillin resistance was observed in 90% of S. aureus isolates. All Gram positive bacteria were found sensitive to vancomycin. In Gram-negative organisms, extended spectrum β-lactamases (ESBL) was observed in 40.5% isolates and resistance to carbapenems was found to be 37.8%. Discussion/Conclusion: In India, most hospitals routinely use single aerobic blood culture. The isolation of CoNS in blood is difficult to interpret hence, proper collection, processing, and relevant clinical information can significantly reduced the chances of contamination. Automated blood culture system can significantly shorten the length of time for isolation and identification compared to the manual techniques which takes about seven days. Resistance to antibiotics is a matter of concern that can result in ineffective treatment.
The Pediatric infectious disease journal, 2016
The multisite community-based study, Aetiology of Neonatal Infection in South Asia (ANISA), uses blood culture as the gold standard for identifying the etiology of neonatal infection. Considering the importance of this age-old diagnostic tool and the risk of contamination, ANISA has employed rigorous measures to prevent contamination at all stages of blood collection, processing and culture. Because contamination may still occur, an independent expert group evaluates the routinely collected clinical and laboratory data to determine whether a blood culture isolate is a contaminant or a true pathogen. This article describes the methodology used by ANISA to determine whether a blood culture isolate is likely to be a true pathogen or a contaminant in neonatal sepsis.
JOURNAL of CLINICAL AND DIAGNOSTIC RESEARCH, 2013
Background: Bloodstream infections are associated with a significant patient morbidity and mortality. The detection of microorganisms in the patients' blood has a great diagnostic and prognostic significance. The early positive results provide valuable diagnostic information, based on which the appropriate antimicrobial therapy can be initiated. Objective: To know the aetiology of the bloodstream infections in the Kathmandu Medical College, Nepal and the antibiotic sensitivity patterns of the causative organisms. Materials and Methods: The blood specimens which were received from May 2010 to October 2010 in Kathmandu Medical College and Teaching Hospital, Kathmandu, Nepal, were processed and all the positive isolates were included in the study. The isolates were identified by the standard laboratory procedures. The antibiotic susceptibility patterns were determined by the modified Kirby Bauer antibiotic sensitivity method. Result: Of the 1089 blood cultures which were received with the suspected cases of blood stream infections, 138 (12.6 %) were bacteriologically positive. Salmonella serotypes were isolated in 42.7% cases of blood stream infections, followed by Klebsiella pneumoniae in 19.5%, Staphylococcus aureus in 15.9% and others in the rest of the cases. All the gram-negative bacilli isolates showed lower degrees of resistance to amikacin and ofloxacin. All the gram positive isolates were sensitive to amikacin, oxacillin and vancomycin. Conclusion: This study stresses on the need for a continued screening and surveillance in the routine blood culture technique for starting with the empiric therapy for blood borne infections.
This Prospective study analyses culture result of 134 blood culture samples received in microbiology laboratory during a five months period between October 2014 and February 2015. We have documented time required for the culture to become positive, time at which culture could be considered negative and the spectrum of isolated organismsms including their antimicrobial susceptibility patterns. The specimens were processed by using automated system BacT/Alert 3D/60. Microorganism’s identification was performed by routine conventional and automated identification system and antibiotic susceptibility testing was done by Kirby bauer disk diffusion method. The mean detection time for isolates was 14.5 +/- 5.7 hours. Among organisms isolated included were Gram positive bacteria, Gram negative bacteria and yeasts with 22 (16.4%), 14 (10.4%) and 19 (14.2%) respectively. All our cultures were positive within 34 hours.
2021
Background: Blood cultures are the most significant samples received in a microbiology laboratory. Good quality control of pre-analytic, analytic, and post-analytic stages can have a significant impact on patient outcomes. Here, we present the improvements brought about by reviewing blood culture data with clinicians at a tertiary care institute in India. Methods: Four-year blood culture data (phase I-February 2014-February 2018) were shared with clinicians in the clinical grand round. Several take-home messages were discussed in a quiz format, and a number of holistic quality control measures were implemented at different levels. Based on observable changes in blood culture reports, another data set was analyzed and compared in phase II (April 2018-April 2019). Results: In phase II, the blood culture contamination rate improved from 6 to 2% along with four times reduction in ICU isolates and three times increased isolation of salmonellae and pneumococci. The development of resistance in Klebsiella pneumoniae to carbapenems and piperacillin-tazobactam was reduced. Colistin resistance in ICU isolates hovered around 15%. Vaccine-preventable pneumococcal serotypes were predominant in the under-five age-group. Typhoidal salmonellae were more commonly isolated from adults with 50% showing sensitivity to pefloxacin and 97% to ampicillin, chloramphenicol, and cotrimoxazole. Candida parapsilosis was the leading non-albicans Candida (NAC). Fluconazole resistance was observed in 50% of NAC. Conclusion: Reviewing blood culture data with clinicians mutually helped us to improve the overall quality of blood culture reports. It had a major impact on epidemiological trends and thus, found to be superior to just sharing an antibiogram with the clinicians.
Jundishapur Journal of Microbiology, 2016
Background: The prognostic value of blood culture testing in the diagnosis of bacteremia is limited by contamination. Objectives: In this multicenter study, the aim was to evaluate the contamination rates of blood cultures as well as the parameters that affect the culture results. Materials and Methods: Sample collection practices and culture data obtained from 16 university/research hospitals were retrospectively evaluated. A total of 214,340 blood samples from 43,254 patients admitted to the centers in 2013 were included in this study. The blood culture results were evaluated based on the three phases of laboratory testing: the pre-analytic, the analytic, and the post-analytic phase. Results: Blood samples were obtained from the patients through either the peripheral venous route (64%) or an intravascular catheter (36%). Povidone-iodine (60%) or alcohol (40%) was applied to disinfect the skin. Of the 16 centers, 62.5% have no dedicated phlebotomy team, 68.7% employed a blood culture system, 86.7% conducted additional studies with pediatric bottles, and 43.7% with anaerobic bottles. One center maintained a blood culture quality control study. The average growth rate in the bottles of blood cultures during the defined period (1259-26,400/year) was 32.3%. Of the growing microorganisms, 67% were causative agents, while 33% were contaminants. The contamination rates of the centers ranged from 1% to 17%. The average growth time for the causative bacteria was 21.4 hours, while it was 36.3 hours for the contaminant bacteria. The most commonly isolated pathogens were Escherichia coli (22.45%) and coagulase-negative staphylococci (CoNS) (20.11%). Further, the most frequently identified contaminant bacteria were CoNS (44.04%). Conclusions: The high contamination rates were remarkable in this study. We suggest that the hospitals' staff should be better trained in blood sample collection and processing. Sterile glove usage, alcohol usage for disinfection, the presence of a phlebotomy team, and quality control studies may all contribute to decreasing the contamination rates. Health policy makers should therefore provide the necessary financial support to obtain the required materials and equipment.
Erciyes Tıp Dergisi/Erciyes Medical Journal, 2015
Objective: Automated blood culture systems are the most preferred and reliable methods. It is very important and also difficult to distinguish whether the microorganism is causative or a contaminant in blood cultures. The aim of this study is to evaluate blood culture results between January 1, 2012 and January 1, 2013. Materials and Methods: Blood samples were cultured by using the BACTEC 9120 automated system. The decision about the growth being a pathogen or contamination was made through clinical findings, laboratory results, and identification of the same microorganism with the same antibiotic susceptibility patterns from blood samples. Results: Of the blood cultures, 43.8% yielded positive results, and 30.4% of them were identified as pathogens, while 13.4% was evaluated as contaminants. The highest contamination rate of 29.8% was observed in the department of cardiology, and the lowest contamination rate of 1.2% was observed in the department of pediatrics. Methicillin-resistant coagulase-negative staphylococci were the most common organisms (19.4%) isolated from blood cultures and assumed as pathogens. Conclusion: Every laboratory should control contamination rates at least once a year and check the results on whether contamination rates are less than 3% or not. If the rates are more than 3%, necessary measures should be taken. The most important measure is to establish phlebotomy teams or to educate all personnel, if this establishment not possible.
The importance of blood cultures in the effective management of bloodstream infections
2019
Background: Bloodstream infection (BSI) is a major public health concern due to its severity-related consequences. These infections pose a human health risk, as they can result in human morbidity and mortality over a short period of time. Blood culture remains the gold standard and major tool for the diagnosis of BSI. Blood culture sampling is commonly indicated before administering antimicrobial therapy, whereas the daily therapeutic adjustment to the antibiogram is an effective intervention in management of BSIs. Compliance with the microbiological criteria-based protocols for pathogen identification and antimicrobial susceptibility testing allow treatment correction within 48-72 hours. Interpretation of positive blood cultures may sometimes present a dilemma for clinicians and microbiologists and, therefore, the test findings should be evaluated in the context of the clinical picture. Conclusions: Over the last decades, we have witnessed an outbreak in the number of BSI studies. The implementation of a standardized algorithm on criteria of a complete blood count sampling, processing and interpretation of the results will help increase the yield rate of BSI pathogens and ultimately improve care management of the patients with BSI. The education and training of medical staff, engaged in BSI patient care is vital in developing good practice, preventing blood culture contamination and obtaining fast and accurate outcomes.