scholarly journals Five-year evaluation of the antimicrobial susceptibility patterns of bacteria causing bloodstream infections in Iran

2011 ◽  
Vol 6 (02) ◽  
pp. 120-125 ◽  
Author(s):  
Babak Pourakbari ◽  
Alireza Sadr ◽  
Mohammad Taghi Haghi Ashtiani ◽  
Setareh Mamishi ◽  
Mahdi Dehghani ◽  
...  

Introduction: Bloodstream infections (BSI) are a serious cause of morbidity and mortality worldwide. Emerging antimicrobial drug resistance among bacterial pathogens causing BSI can limit therapeutic options and complicate patient management. Methodology: To encourage the prudent use of appropriate antibiotics in our pediatric population at Children's Medical Center Hospital, Tehran, Iran, we studied the frequency and antibiogram patterns of blood culture isolates from January 2001 to December 2005. Results: Of 25,223 blood cultures examined, 2,581 (10.23 %) were positive for bacterial growth. The frequency of Gram-positive bacteria isolated was 47.6% (1228 of 2581) and that for Gram-negatives was 52.4% (1353 of 2581). The rates of methicillin (oxacillin) resistance in Staphylococcus aureus and coagulase-negative staphylococci (CoNS) were 79% and 89%, respectively. About 45% of Streptococcus pneumoniae were resistant to trimethoprim-sulfamethoxazole and approximately 66% to penicillin. Among the Gram-negative isolates, Pseudomonas aeruginosa was most frequently isolated, representing 943 (36.7%) over five years. This possibly represents an unrecognized hospital outbreak or contamination of blood culture bottles or other products such as skin disinfectants. Additionally, this pathogen showed extremely high rates of antimicrobial resistance. There were notable differences in frequency of the five most common microorganisms isolated from blood cultures, which can help set priorities for focused infection control efforts. Conclusions: Our findings underscore the need to monitor blood culture isolates and their antimicrobial resistance patterns to observe resistance trends that would influence appropriate empiric treatment and infection control strategies for bacteremic children.  

2004 ◽  
Vol 132 (5) ◽  
pp. 921-925 ◽  
Author(s):  
M. MÜLLER-PREMRU ◽  
P. ČERNELČ

Catheter-related bloodstream infection (CRBSI) caused by coagulase-negative staphylococci (CNS) is common in haematological patients with febrile neutropenia. As the clinical signs of CRBSI are usually scarce and it is difficult to differentiate from blood culture contamination, we tried to confirm CRBSI by molecular typing of CNS isolated from paired blood cultures (one from a peripheral vein and another from the central venous catheter hub). Blood cultures were positive in 59 (36%) out of 163 patients. CNS were isolated in 24 (40%) patients; in 14 from paired blood cultures (28 isolates) and in 10 from a single blood culture. CNS from paired blood cultures were identified as Staphylococcus epidermidis. Antimicrobial susceptibility was determined and bacteria were typed by pulsed-field gel electrophoresis (PFGE) of bacterial genomic DNA. In 13 patients, the antibiotic susceptibility of isolates was identical. The PFGE patterns from paired blood cultures were identical or closely related in 10 patients, thus confirming the presence of CRBSI. In the remaining four patients they were unrelated, and suggested a mixed infection or contamination. Since CNS isolates from three patients had identical PFGE patterns, they were probably nosocomially spread amongst them.


2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S157-S157
Author(s):  
Sujeet Govindan ◽  
Luke Strnad

Abstract Background At our institution, we learned the frequency of blood cultures was sometimes being changed from “Once” to “Daily” without a defined number of days. We hypothesized this led to unnecessary blood cultures being performed. Methods Over a 3 month period from 12/6/2019-3/6/2020, we retrospectively evaluated the charts of patients who had a blood culture frequency changed to “Daily”. We evaluated if there was an initial positive blood culture within 48 hours of the “Daily” order being placed and the number of positive, negative, or “contaminant” sets of cultures drawn with the order. Contaminant blood cultures were defined as a contaminant species, present only once in the repeat cultures, and not present in initial positive cultures. Results 95 unique orders were placed with 406 sets of cultures drawn from 89 adults. ~20% of the time (17 orders) the order was placed without an initial positive blood culture. This led to 62 sets of cultures being drawn, only 1 of which came back positive. 78/95 orders had an initial positive blood culture. The most common initial organisms were Staphylococcus aureus (SA) (38), Candida sp (10), Enterobacterales sp (10), and coagulase negative staphylococci (7). 43/78 (55%) orders with an initial positive set had positive repeat cultures. SA (26) and Candida sp (8) were most common to have positive repeats. Central line associated bloodstream infections (CLABSI) were found in 5 of the orders and contaminant species were found in 4 of the orders. 54% of the patients who had a “Daily” order placed did not have positive repeat cultures. The majority of the cultures were drawn from Surgical (40 orders) and Medical (35 orders) services. Assuming that SA and Candida sp require 48 hours of negative blood cultures to document clearance and other species require 24 hours, it was estimated that 51% of the cultures drawn using the "Daily" frequency were unnecessary. Cost savings over a year of removing the "Daily" frequency would be ~&14,000. Data from "Daily" blood culture orders drawn at Oregon Health & Science University from 12/6/2019-3/6/2020 Conclusion Unnecessary blood cultures are drawn when the frequency of blood cultures is changed to "Daily". Repeat blood cultures had the greatest utility in bloodstream infections due to SA or Candida sp, and with CLABSI where the line is still in place. These results led to a stewardship intervention to change blood culture ordering at our institution. Disclosures All Authors: No reported disclosures


2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S147-S147
Author(s):  
Hanh Bui ◽  
Frank Tverdek ◽  
Stephanie Carnes ◽  
Jeannie D Chan ◽  
Andrew Bryan ◽  
...  

Abstract Background Harborview Medical Center (HMC) identifies organisms and an ESBL genotype (CTX-M) via Verigene® Gram-Negative Blood Culture Nucleic Acid Test (BC-GN). University of Washington-Montlake (UWML) uses matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for organism identification directly from positive blood cultures and ceftriaxone results by Kirby Bauer disk diffusion (KB) are reported 18 hours later. No ESBL comment is reported at UWML. We aimed to determine whether the methodology in identification and reporting of ESBL-E from blood cultures between two hospitals has an impact on time to preferred therapy with a carbapenem antibiotic. Methods Retrospective observational study conducted at UWML and HMC in Seattle, WA between 1/10/2015 and 9/15/2020. Adult patients were eligible if they had ≥1 positive blood culture with an Enterobacteriaceae isolate resistant to ceftriaxone and were on antibiotic treatment. The primary outcome was the difference in time to preferred definitive therapy with a carbapenem antibiotic in patients an ESBL-E bloodstream infection (BSI) identified by Verigene® vs. MALDI-TOF MS/KB. Results A total of 199 patients were screened; 67 were included for UWML and 68 at HMC. The average time to initiation of a carbapenem antibiotic was 42 ±26.5 hours at UWML and 28 ±19.7 hours at HMC. A t-test detected a difference in time to preferred therapy between a Verigene® vs. MALDI-TOF MS/KB tested ESBL-E BSI [95% confidence interval (CI), 5.3-22.9]. The hazard ratio to carbapenem initiation for HMC is 1.73643 [95% CI, 1.1405-2.644]. Conclusion A statistically significant difference in time to preferred definitive therapy among patients with an ESBL-E BSI processed by Verigene® was found compared to MALDI-TOF MS. The results suggest standardization in protocols between the UWML and HMC hospitals is warranted. Disclosures Andrew Bryan, MD, PhD, Shionogi Inc. (Grant/Research Support)


2020 ◽  
Vol 154 (Supplement_1) ◽  
pp. S140-S140
Author(s):  
E Abada ◽  
M Y Khan ◽  
N Yerrapotu ◽  
V Pardeshi ◽  
F Zaiem ◽  
...  

Abstract Introduction/Objective Bacterial infection is a significant cause of morbidity and mortality. Prompt identification of microorganisms and their susceptibilities to antimicrobial therapies is critical in the management of patients with bloodstream infections. Blood cultures are collected in paired aerobic and anaerobic bottles. However, transport delays might allow some organisms to grow extensively prior to incubation in the blood culture instruments, leading to false-negative culture results. The Detroit Medical Center utilizes the BD Bactec™ instruments for blood culture incubation and the Verigene DNA-based molecular assay for the identification of bacteria and major resistance genes. It has a core microbiology lab that serves 6 hospitals, however, 2 of the hospitals are remotely located. The aim of this project was to determine if transportation delays led to significant false-negative culture results. If significant false negativity occurred, additional Bactec™ instruments would need to be purchased. Methods For one month, we tracked the collection of blood cultures to incubation time at one of the remote hospitals. All blood cultures that remain negative after 164 hours of incubation are routinely discarded. However, in this case, they were subcultured to a Petri plate containing chocolate agar for 30 days. Any organisms that grew were identified by standard lab techniques. Results Of the 547 negative culture bottles that were subcultured for possible false-negative results, only 3 (0.5%) bottles grew bacteria. All three were isolated from different patients. The mean time from blood collection to incubation in the instrument was 4-8 hours. The isolates either met criteria for contaminated cultures, or they grew the same pathogen that had previously been identified in the paired bottle from the same culture. The organisms isolated include coagulase negative Staphylococcus species, Staphylococcus pettenkoferi, and Pseudomonas aeruginosa. No unexpected pathogenic organisms were detected. Conclusion Our results demonstrate that prolonged pre-analytical time does not lead to false-negative blood culture results. The patients’ diagnoses were not changed, therefore, the purchase of additional blood culture instruments was not necessary. However, transportation time from the patient floors to the main microbiology lab needs to be improved to meet the recommended 2 hours pre-analytical time.


2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S42-S42
Author(s):  
Lauren Groft ◽  
James Mease ◽  
Jacqueline Bork ◽  
Ciera L Bernhardi ◽  
J Kristie Johnson ◽  
...  

Abstract Background Routine follow-up blood cultures (FUBC) are strongly recommended for Staphylococcus aureus and Candida spp. bloodstream infections (BSI), but the role of FUBC in Gram-negative (GN) BSI remains controversial. Factors that may result in persistent GN BSI include critical illness, endovascular infection, lack of source control, multidrug resistant organisms (MDRO), end-stage renal disease, or immunocompromised status. As such, FUBC in patients with any of these factors may be warranted to improve clinical outcomes, but the true balance of benefit versus harm remains unknown. Our objective was to evaluate the role of FUBC in immunocompromised patients with GN BSI. Methods This was a retrospective observational cohort of adult, immunocompromised patients treated for confirmed GN BSI between January 2019 and December 2020 at University of Maryland Medical Center. Immunocompromise was defined as active hematologic or solid tumor malignancy at time of BSI diagnosis, history of hematopoietic stem cell transplantation (HSCT) or solid organ transplantation (SOT), or absolute neutrophil count (ANC) < 1000 cells/mm3 at any time 30 days prior to BSI diagnosis. FUBC were defined as blood cultures drawn between 24 hours and 7 days from index blood culture, within the same hospital encounter. Positive FUBC was defined as a FUBC with same pathogenic GN organism identified. Comparison of patient and microbiologic characteristics was made between patients with and without FUBC. Results A total of 146 patients with GN BSI were included. Baseline characteristics are reported in Table 1. FUBC were collected in 129 (88.4%) patients. Neutropenia (49.6% vs. 19.4%, P=0.122), presence of central line (69.8% vs. 30.2%, P=0.061), and hospital-acquired origin of BSI (63.6% vs. 36.4%, P=0.395) resulted in increased frequency of FUBC. Patients with FUBC had a significantly longer post-BSI mean (SD) length of stay (17.3 [35.4] vs. 6.5 [6.0] days; P=0.005). Positive FUBC occurred in only 2 cases (1.4%) and both patients had persistent fevers at time of FUBC. Table 1. Baseline Characteristics Conclusion Positive FUBC were uncommon in this immunocompromised cohort with GN BSI, which challenges the need for routine collection of FUBC in this patient population. Disclosures Ciera L. Bernhardi, PharmD, Servier Pharmaceuticals (Advisor or Review Panel member) J. Kristie Johnson, PhD, D(ABMM), GenMark (Speaker’s Bureau) Kimberly C. Claeys, PharmD, GenMark (Speaker’s Bureau)


1985 ◽  
Vol 6 (12) ◽  
pp. 479-486 ◽  
Author(s):  
Louis V. Kirchhoff ◽  
John N. Sheagren

AbstractCoagulase-negative staphylococci are frequently isolated from blood cultures. As these organisms may occasionally cause serious disease, differentiating bacteremia from contamination is very important but often difficult. Over a 26-month period, of 29,542 blood cultures processed at the University of Michigan Medical Center, 2,875 (9.7%) were positive, and of those, 694 (from 527 patients) grew coagulase-negative staphylococci. Isolates from the 439 patients with only one blood culture positive for coagulase-negative staphy-lococci and those from the 18 patients with two positive cultures 10 days or more apart were deemed contaminants. Review of the records of the remaining 70 patients with multiple isolates indicated that 33 had had an episode of true bacteremia, 29 (87.9%) of which were associated with intravascular catheters or prosthetic valves. Overall, 85% of all coagulase-negative staphylococci isolated during the study period were judged to be contaminants. Seventy-one percent of the blood cultures drawn during the episodes of bacteremia were positive for coagulase-negative staphylococci as opposed to only 34% in the patients with contaminated cultures (p < 0.01). Moreover, coagulase-negative staphylococci grew in both aerobic and anaerobic bottles in 85% of blood culture sets drawn during episodes of bacteremia, but in only 30% of the cultures thought to be contaminated (p < 0.001). Growth of coagulase-negative staphylococci in less than 48 hours was also significantly associated with bacteremia (p < 0.01). Antibiotic sensitivity patterns were not useful in differentiating bacteremia from contamination. Thus, clinicians should consider coagulase-negative staphylococci as true blood pathogens in patients with intravascular devices who have a high proportion of blood cultures positive for this organism over a short period of time, and whose cultures became positive in less than 48 hours, with a high percent positive in both bottles. Microbiology laboratories can conserve considerable resources by limiting sensitivity studies to isolates from such patients.


2020 ◽  
Vol 20 (2) ◽  
pp. 229-236
Author(s):  
Sepideh Keshavarz Valian ◽  
Shima Mahmoudi ◽  
Babak Pourakbari ◽  
Maryam Banar ◽  
Mohammad Taghi Haghi Ashtiani ◽  
...  

Objective: The study aimed to describe the identity and antimicrobial resistance patterns of the causative agents of bacterial meningitis in children referred to Children’s Medical Center (CMC) Hospital, Tehran, Iran. Methods: This retrospective study was performed at CMC Hospital during a six-year period from 2011 to 2016. The microbiological information of the patients with a diagnosis of bacterial meningitis was collected and the following data were obtained: patients’ age, sex, hospital ward, the results of CSF and blood cultures, and antibiotic susceptibility profiles of isolated organisms. Results: A total of 118 patients with bacterial meningitis were admitted to CMC hospital. Sixty-two percent (n=73) of the patients were male. The median age of the patients was ten months (interquartile range [IQR]: 2 months-2 years) and the majority of them (n=92, 80%) were younger than two years of age. The highest number of patients (n=47, 40%) were admitted to the surgery department. Streptococcus epidermidis was the most frequent isolated bacterium (n=27/127, 21%), followed by Klebsiella pneumoniae (n=20/127, 16%), and Staphylococcus aureus (n=16/127, 12.5%). Blood culture was positive in 28% (n=33/118) of patients. Ampicillin-sulbactam and imipenem were the most effective antibiotics against Gram-negative bacteria isolated from CSF cultures. In the case of Gram-positive organisms, ampicillinsulbactam, vancomycin, and linezolid were the best choices. Imipenem was the most active drug against Gram-negative blood pathogens. Also, ampicillin and vancomycin had the best effect on Gram-positive bacteria isolated from blood cultures. Conclusion: Results of this study provide valuable information about the antibiotic resistance profiles of the etiologic agents of childhood meningitis, which can be used for prescription of more effective empirical therapies.


2021 ◽  
Vol 9 (6) ◽  
pp. 1170
Author(s):  
Gabriel Haddad ◽  
Sara Bellali ◽  
Tatsuki Takakura ◽  
Anthony Fontanini ◽  
Yusuke Ominami ◽  
...  

Blood culture is currently the most commonly used method for diagnosing sepsis and bloodstream infections. However, the long turn-around-time to achieve microbe identification remains a major concern for clinical microbiology laboratories. Gram staining for preliminary identification remains the gold standard. We developed a new rapid strategy using a tabletop scanning electron microscope (SEM) and compared its performance with Gram staining for the detection of micro-organisms and preliminary identification directly from blood cultures. We first optimised the sample preparation for twelve samples simultaneously, saving time on imaging. In this work, SEM proved its ability to identify bacteria and yeasts in morphotypes up to the genus level in some cases. We blindly tested 1075 blood cultures and compared our results to the Gram staining preliminary identification, with MALDI-TOF/MS as a reference. This method presents major advantages such as a fast microbe identification, within an hour of the blood culture being detected positive, low preparation costs, and data traceability. This SEM identification strategy can be developed into an automated assay from the sample preparation, micrograph acquisition, and identification process. This strategy could revolutionise urgent microbiological diagnosis of infectious diseases.


PEDIATRICS ◽  
1990 ◽  
Vol 86 (2) ◽  
pp. 157-162
Author(s):  
Joseph W. St Geme ◽  
Louis M. Bell ◽  
Stephen Baumgart ◽  
Carl T. D'Angio ◽  
Mary Catherine Harris

Coagulase-negative staphylococci represent the most common cause of serious nosocomial infection in many intensive care nurseries. However, these organisms are also common blood culture contaminants. To determine the value of quantitative blood cultures in distinguishing sepsis from culture contamination, we reviewed records of all infants in our nurseries who had peripheral blood isolates of coagulase-negative staphylococci during a 3-year period. Twenty-three episodes of sepsis were identified in 21 infants, and 10 infants had blood culture contamination. Colony counts from the initial peripheral blood culture were significantly different for the two study groups (P &lt; .001). In 9 of 23 episodes of sepsis, the initial peripheral blood culture grew &gt;100 colony-forming units (cfu) per mL. In the other 14 episodes, the initial culture yielded ≤50 cfu/mL. All 10 infants with culture contamination had colony counts of &lt;50 cfu/mL, and in 9 the initial peripheral blood culture grew &lt;20 cfu/mL. Infants with sepsis, including those with colony counts of ≤50 cfu/mL, were significantly more likely to have a central catheter or an abnormal hematologic value or both (P &lt; .05). Infants who lacked these clinical features were more likely to have contamination. We conclude that quantitative blood cultures in conjunction with specific clinical information may distinguish sepsis from culture contamination with coagluase-negative staphylococci in young infants. In addition, low colony-count growth should not be ignored as contamination in this high-risk population.


2018 ◽  
Vol 56 (9) ◽  
Author(s):  
Paul A. Granato ◽  
Melissa M. Unz ◽  
Raymond H. Widen ◽  
Suzane Silbert ◽  
Stephen Young ◽  
...  

ABSTRACT The iC-GPC Assay (iCubate, Huntsville, AL) is a qualitative multiplex test for the detection of five of the most common Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium) responsible for bacterial bloodstream infections, performed directly from positive blood cultures. The assay also detects the presence of the mecA, vanA, and vanB resistance determinants. This study comparatively evaluated the performance of the iC-GPC Assay against the Verigene Gram-positive blood culture (BC-GP) assay (Luminex Corp., Austin, TX) for 1,134 patient blood culture specimens positive for Gram-positive cocci. The iC-GPC Assay had an overall percent agreement with the BC-GP assay of 95.5%. Discordant specimens were further analyzed by PCR and a bidirectional sequencing method. The results indicate that the iC-GPC Assay together with the iCubate system is an accurate and reliable tool for the detection of the five most common Gram-positive bacteria and their resistance markers responsible for bloodstream infections.


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