Blood Culture Isolates Research Articles

Antimicrobial susceptibility testing of Eggerthella lenta blood culture isolates at a university hospital in Belgium from 2004 to 2018

ObjectivesEggerthella lenta is a Gram-positive anaerobic bacillus that is an important cause of bloodstream infections. This study aims to test the susceptibility of Eggerthella lenta blood culture isolates to commonly used antibiotics for the empirical treatment of anaerobic infections. MethodsIn total, 49 positive blood cultures for Eggerthella lenta were retrospectively included from patients hospitalised at the Universitair Ziekenhuis Brussel, Belgium, between 2004 and 2018. Identification was done by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system. Antimicrobial susceptibility testing was performed using the reference agar dilution method according to Clinical and Laboratory Standards Institute (CLSI) guidelines with Brucella agar supplemented with 5 μg/mL hemin, 1 μg/mL vitamin K1 and 5% laked sheep blood.The minimal inhibitory concentrations were interpreted using the EUCAST breakpoints. Clinical characteristics were collected by reviewing the patient’s medical records. ResultsAll isolates were susceptible to amoxicillin-clavulanate, metronidazole and meropenem. Eighty-eight % of them were susceptible to clindamycin and 94% (20% S, 74% I) were susceptible to piperacillin-tazobactam. The mean age of the patients was 64 (±20) and they showed a 30-day mortality of 27%. The source of infection was in 65.3% of the cases abdominal, 20.4% were sacral pressure ulcers and 14.3% were unknown causes.While all isolates were fully susceptible at standard dosing regimen to amoxicillin-clavulanate, most were only susceptible at increased exposure or resistant to piperacillin-tazobactam. ConclusionsOur results suggest to be careful with the use of piperacillin-tazobactam and clindamycin in the empirical treatment of Eggerthella lenta infections.

Bacterial contamination of neonatal intensive care units: How safe are the neonates?

BackgroundIntensive care units (ICU) are essential healthcare facility for life threatening conditions. Bacterial contamination of objects/instruments in ICU is an important source of nosocomial infections. This study is aimed to determine the level of bacterial contamination of instruments/objects which are commonly touched by healthcare workers and frequently come in contact with the neonates.MethodsThis hospital based prospective study was conducted in neonatal intensive care unit (NICU) of Manipal Teaching Hospital, Pokhara, Nepal. A total of 146 samples collected from surfaces of incubators, radiant warmers, suction tips, ventilators, stethoscopes, door handles, weighing machines, mothers’ beds, phototherapy beds, laryngoscope, telephone sets, blood pressure machine, etc. formed the material of the study. Isolation, identification and antibiotic susceptibility of the bacterial isolates was performed by standard techniques. Blood culture isolates from NICU patients during the study period were compared with the environmental isolates.ResultsOut of 146 samples, bacterial growth was observed in 109. A total of 119 bacterial isolates were retrieved from 109 samples. Three common potential pathogens isolated were Escherichia coli (n = 27), Klebsiella species (n = 21) and Staphylococcus aureus (n = 18). Majority of E. coli and Klebsiella isolates were from incubators, suction tips and mothers’ beds. Majority of S. aureus isolates were cultured from radiant warmers. Among S. aureus isolates, 33.3% (6/18) were methicillin resistant. Majority of the bacterial isolates were susceptible to gentamicin and amikacin. Common potential pathogens isolated from blood culture of NICU patients were S. aureus and Klebsiella species.ConclusionHigh degree of bacterial contamination of objects/instruments in NICU was recorded. Isolation of potential pathogens like E. coli, Klebsiella species and S. aureus is a major threat of nosocomial infections. Blood culture data of NICU reflects possibility of nosocomial infections from contaminated sites. Gentamicin and amikacin may be used for empirical therapy in suspected cases of nosocomial infections in NICU.

Characteristics and outcomes of bacteremic pneumococcal pneumonia of patients with and without HIV infection in Argentina

Streptococcus pneumoniae is the main causative agent of pneumonia, with a 10 to 25 percent rate of isolation in blood cultures. Controversies exist regarding the prognostic impact of a history of human immunodeficiency virus (HIV) infection on community-acquired pneumonia. The aim of our work was to analyze and compare the clinical presentation, radiological findings and progression of pneumococcal pneumonia in patients infected with and not infected with HIV. We retrospectively analyzed adult patients with positive blood cultures for Streptococcus pneumoniae and clinical and radiological findings compatible with pneumonia in the period between January 2012 and May 2017. Age, sex, comorbidities, clinical and laboratory variables, radiological severity, progression and mortality were analyzed. Comparative analysis between HIV-positive and -negative patients was carried out. Receiver operating curves (ROC) for CURB-65 were performed to predict mortality in both groups. We included 107 patients (21 HIV-positive and 86 HIV-negative). HIV patients were on average younger (38 vs 58 years) with lower hematocrits (31.7 vs 36.5%) and fewer comorbidities (47 vs 72%). Overall mortality was 36 percent, and the area under the curve (AUC) of the CURB-65 ROC was 0.69 (95% confidence interval: 0.58–0.79) for all patients without differences between the two groups. Patients with a history of HIV infection had the same progression and mortality as the group of patients without that background.

Fighting the Rising Spectre of Tough Bugs in Tough Clinical Scenario: A Ten Year Experience from a Hemato-Oncology Centre in Tertiary Health Care Facility in North India

Introduction: Infections with multi drug resistant (MDR) organisms pose a major challenge in achieving optimal success in pediatric oncology patients. Aim: We aimed to study the evolving blood stream flora, its antibiotic resistance pattern and impact of a rigorous antibiotic stewardship programme at our center. Materials and Methods: A 10 year retrospective analysis was performed on suspected episodes of septicemia in pediatric oncology patients. Blood culture isolates, resistance patterns and clinical outcome of corresponding septic episodes were studied over two time periods- TP1 (2007-2013) and TP2 (2014-2018). Results: Of 1423 blood culture samples, 285 were positive. TP1 showed predominant growth of Gram negative bacteria (GNB-48.5%) and TP2 showed isolates that were mainly Gram positive cocci (GPC-50.3%) reflecting increased use of central lines. Coagulase negative Staphylococcus (CoNS) was the commonest GPC and E. coli was the most common GNB isolated in TP2. Cefaperazone sulbactum monotherapy was used as the first line antimicrobial for neutropenic fever in our unit in TP2 and it was observed that 72% of the GNB were sensitive to this drug. In the comparative analysis of TP2 vs TP1, it was observed that the GNB isolates showed increasing resistance to Carbapenems. Interestingly, a declining trend of resistance was observed with Chloramphenicol for both GNB/GPC. Flouroquinolone resistance has consistently been high over the two time periods. No in vitro resistance was identified to Glycopeptides and Colistin over TP1 and TP2. Mortality rates in children blood culture positivity remained the same across TP1 and TP2 (2.2 vs. 2.6%). Conclusion: Despite rising incidence of MDR bacteria, a rigorous antibiotic stewardship programme helps maintain good outcomes in pediatric oncology patients with sepsis. Early diagnosis, judicious use of antibiotics and de-escalation after initial stabilization may help. Innovative strategies to fight drug resistance are being evolved.

Biphasic Versus Monophasic Manual Blood Culture Bottles for Low-Resource Settings: An In-Depth <i>in vitro</i> Evaluation Using Simulated Blood Cultures

Introduction: Manual (visually read) blood culture bottles (BCB) are frequently used in low-resource settings (LRS) where automated alternatives are less suitable. Yet performance evaluations of these BCBs are lacking, especially in comparison to automated systems. We evaluated two manual BCB types (the Bi-State BCB, Autobio; visually read BacT/ALERT bottles, bioMerieux) and used BacT/ALERT BCB monitored in a BacT/ALERT automate as a reference method. Methods: BCBs were spiked in triplicate with 177 clinical isolates representing pathogens frequently found in LRS (19 bacterial, 1 yeast species) for both adult and pediatric formulations. Growth in manual BCBs was evaluated by visually inspecting the broth, agar slant, and – for BacT/ALERT BCB – color change of the growth indicator. Blind subculture was conducted after overnight incubation (Day 1). Results: Overall yield was 95·9% and 95·5% for Bi-State and manual BacT/ALERT respectively, versus 96·1% for the reference method. The lowest yield occurred for Neisseria meningitidis and Burkholderia cepacia (83·3% and 83·1%) and was consistent among the three BC systems. On Day 1, growth was detected in 90·7% and 75·0% of grown BCBs in Bi-State and BacT/ALERT respectively, versus 99·3% for the reference method. On Day 2 detection rates were 100%, 97·7% and 100% respectively. Among 1013 grown Bi-State BCBs, growth mostly co-occurred in broth and slant (81·7%). Sufficient colony growth on the slant to perform further tests was present in only 44·1% and 59·0% of biphasic bottles on Day 2 and Day 3 respectively. Blind subculture generated colonies on Day 2 for 99·7% grown Bi-State and 99·2% of manual BacT/ALERT bottles respectively. Conclusion: In these in-vitro experiments, the yield and time-to-detection of manual BCBs were comparable to an automated system. Bi-State BCBs outperformed manual BacT/ALERT bottles, but the agar slant did not allow earlier detection nor earlier colony growth when compared to blind subculture on Day 1. Funding Statement: This research was funded by Medecins Sans Frontieres (Mini-Lab project). Medecins Sans Frontieres participated in study design, interpretation and writing of the manuscript. Declaration of Interests: None to declare. Ethics Approval Statement: Leftover blood from blood bank volunteers was used under research contract (file number CM20180327A). Clinical strains were obtained from ITM travel clinic and microbiological surveillance studies (Surveillance of antimicrobial resistance among consecutive blood culture isolates in tropical settings, Institutional Review Board 613/08, Ethical Committee University Hospital of Antwerp 8/20/96).

Health vigilance concerning bacteremia in neonatology - neonatal intensive care unit at the Mohammed VI University Hospital of Oujda (Morocco): epidemiological profile and antibiotic resistance

The objective of our study was to describe the epidemiological profile of blood culture isolates in the neonatology - neonatal intensive care unit of the Mohammed VI University Hospital of Oujda (Morocco) and to specify the resistance profile of the main germs isolated to antibiotics .This is a retrospective and descriptive study of 21 months from December 14, 2016 to September 14, 2018 and covering all positive blood cultures processed in the microbiology laboratory in accordance with REMIC (reference in medical microbiology) and EUCAST (European Committee on Antimicrobial Susceptibility Testing).contaminated blood cultures were excluded. As results, we collected 275 positive blood cultures. They occurred in the context of intravascular device (IVD) use in 59% (n=162) of cases. The most isolated bacterial groups were coagulase-negative staphylococci (CNS) 41.45 %( n=114), followed by Enterobacteriaceae 32.36 %( n=89).CNS were resistant to all beta-lactams in 57.89 %( n=66), and to glycopeptides in 5.26 %( n=6). Enterobacteriaceae were producers of extended-spectrum betalactamases in 79.77% (n=71) and producers of carbapenemases in 13.48% (n=12) of cases. The alarming increase of enterobacteriaceae isolates and their antibiotic resistance rates should encourage the reinforcement of hygiene measures in our University Hospital.

118. Optimizing the management of coagulase-negative staphylococci (CoNS) contaminants by reporting the species name

BackgroundCoNS are common isolates in blood cultures (BCx), but many are contaminants contributing to unnecessary antibiotic use. When CoNS are isolated from multiple BCx, different species and/or different susceptibility patterns may suggest contamination. Species reporting of CoNS is not performed at all hospitals. The purpose of this study was to characterize antibiotic use attributable to CoNS positive (pos) BCx and determine if reporting CoNS species could help reduce unnecessary antibiotics.MethodsA retrospective chart review was conducted of inpatients at an academic medical center before (Jan-June 2017) and after (Sept 2019-Feb 2020) implementation of CoNS species reporting. CoNS species were hidden to providers in the before group. Patients (pts) ≥18 years old with ≥1 BCx pos for CoNS were included. Pts who were neutropenic, treated with anti-staphylococcal antibiotics (SAbx) for a non-CoNS infection, or treated for CoNS with non-SAbx were excluded. Pts were categorized by number of pos BCx (1 vs ≥2). In each period, a random sample of pts was screened until 50 pts with 1 CoNS pos BCx were included. Additional data were collected until at least 50 pts with ≥2 pos BCx were included in each period. The primary outcome was use of SAbx among pts in each group before and after species reporting. Additional analyses were performed to compare the use of SAbx among subsets with same/different species and/or susceptibilities.Results203 pts were included, 102 before and 101 after. 51% and 50% had ≥2 pos BCx in the before and after groups, respectively. S. epidermidis was isolated more frequently in pts with ≥2 pos BCx (75% vs 50%, p< 0.001). 77% of pts received at least 1 SAbx (97% vancomycin). Median SAbx days of therapy per pt (DOTs) was greater among pts with ≥2 pos BCx (1 vs 5, p< 0.001). There was no difference in overall DOTs between the two periods (3 vs 2, p=0.25). However, among pts with ≥2 pos BCx, median DOTs was less in the after period (6.5 vs 3, p=0.016). Among pts with 1 pos BCx, median DOTs was 1 in both periods.Median Anti-Staphylococcal Antibiotic Days of Therapy per Patient (≥ 2 positive cultures) ConclusionCoNS species reporting was associated with decreased SAbx use for pts with ≥2 pos BCx, suggesting that knowing the species helps in determining likelihood of true infection. Institutions may realize improved stewardship metrics of SAbx by implementing CoNS species reporting for pos BCx.Disclosures Tyler J. Stone, PharmD, Paratek (Research Grant or Support) Elizabeth Palavecino, MD, Paratek (Grant/Research Support)Paratek (Grant/Research Support) John Williamson, PharmD, Paratek (Research Grant or Support)

1439. High Rates of Drug Resistance in Escherichia coli from a Pilot Antimicrobial Resistance Surveillance System in Cambodia

BackgroundAntimicrobial resistance (AMR) is a major and growing global public health problem. The Cambodia Ministry of Health established a pilot laboratory-based AMR surveillance system for blood specimens in 2017. The objective of this study is to characterize AMR among pathogenic isolates from blood samples.MethodsA retrospective analysis was performed using one year of data from a pilot AMR Surveillance system in Cambodia. Four blood culture isolate pathogens were included: Escherichia coli, Klebsiella pneumoniae, Salmonella Typhi /Salmonella Paratyphi A and Staphylococcus aureus. Blood culture isolates that were referred from eleven sentinel sites were analyzed at the National Public Health Laboratory for identification. Antibiotic susceptibility testing (AST) was done using disk diffusion, minimum inhibitory concentration method following Clinical Laboratory Standard Institute (CLSI) guidelines.ResultsAmong 214 pathogenic isolates from blood samples, E.coli was the most common (56.1%), followed by Salmonella Typhi/Salmonella Paratyphi A (18.7%), Staphylococcus aureus (13.5%), and Klebsiella pneumoniae (11.7%). Methicillin Resistance Staphylococcus aureus (MRSA) was detected in half of the isolates. E.coli was resistant to ampicillin (94.4%), trimethoprim-sulfamethoxazole (84.5%), and ceftriaxone (79.2%). Salmonella Typhi was resistant to ampicillin (73.3%) and trimethoprim-sulfamethoxazole (60.0%) and Salmonella Paratyphi A were resistant to fluoroquinolones (91.7%). For last resort antibiotics, E.coli was resistant to carbapenem groups (3.2% for imipenem, 4.9% for meropenem, and 5.0% for ertapenem). Klebsiella pneumoniae was not resistant to any groups.Conclusion E.coli was found at high rates in blood samples and was resistant to common antibiotics used in Cambodia. These pilot data show the importance of establishing a national AMR surveillance system in Cambodia to monitor AMR trends following GLASS guidelines.Disclosures All Authors: No reported disclosures

1378. Reservoirs of Transmission of Resistant Gram-negative Pathogens Responsible for Neonatal Sepsis among Hospitalized Neonates in Pune, India

BackgroundNeonatal infections with resistant Gram-negative (GN) organisms are associated with high rates of mortality, with limited antibiotic treatment options. The role of maternal colonization and environmental GN organisms as reservoirs for transmission to neonates has not been well described.MethodsWe performed a prospective cohort study from October 12, 2018, until October 31, 2019, to describe the role of maternal and environmental GN colonization in BSI among neonates admitted to the neonatal intensive care unit (NICU) at a tertiary care center in Pune, India. Women admitted to Labor & Delivery with risk factors for neonatal sepsis who provided consent were enrolled and their neonates were followed until hospital discharge. For neonates who developed bloodstream infection (BSI), colonization with resistant GN organisms was assessed in their mothers from frozen vaginal and rectal swabs collected at enrollment and at delivery and in the neonates from frozen skin swabs and peri-rectal swabs collected at day of life (DOL) 0, 3, 7, and weekly until discharge. Environmental colonization was assessed with weekly sampling of unit sinks and the immediate neonatal care environment. Colonization samples were processed to identify organisms that matched neonatal blood culture isolates.Results953 women were enrolled, of whom 741 (78%) received antepartum antibiotics. Among 987 live born neonates, 12 (1%) died in the delivery room and 257 (26%) required NICU admission. Among neonates admitted to the NICU, 143 (56%) had at least one blood culture, of which 28 (20%) were positive; 21 (75%) had a GN BSI. The most common cause of neonatal BSI was Klebsiella pneumoniae, and 8 (38%) GN BSI were due to a carbapenem-resistant organism. No organism isolated from maternal samples matched organism and resistance pattern from neonatal blood culture. Matching strains were found in unit sinks and neonatal rectal and skin samples (Figure 1).Organism recovery from swabs and match to bloodstream isolate by sample source and time of collection from birth ConclusionAmong neonates born to mothers with risk factors for neonatal sepsis, GN organisms were the most common cause of neonatal BSI. Environmental and neonatal colonization may represent important reservoirs of transmission for these pathogens among neonates hospitalized in a tertiary care NICU in Pune, India.Disclosures All Authors: No reported disclosures

97. Assessment of the accuracy of direct antimicrobial susceptibility testing from positive blood cultures in pediatric patients and its utility as an antimicrobial stewardship tool

BackgroundHospitalized pediatric patients with bacteremia receive broad-spectrum antibiotics while organism identification and antibiotic susceptibilities are pending. Direct susceptibility testing (DST) using unstandardized Kirby-Bauer disk diffusion provides early results before standardized (final) antimicrobial susceptibility testing (AST) is available. The accuracy of DST in comparison with AST has been poorly studied. If DST is highly accurate, it could facilitate earlier de-escalation of antibiotics.MethodsRetrospective cohort study of all positive blood cultures at Boston Children’s Hospital between January 1, 2017 and October 20, 2019. Isolates were eligible for inclusion if a DST result was available. Isolates were excluded if more than one organism grew from a blood culture or if a patient had repeat blood cultures positive for the same organism within 14 days. Patient characteristics and antibiotic orders were identified via a local data warehouse. Positive and negative predictive value (PPV: accuracy of susceptibility on DST in identifying susceptibility on AST result; NPV: accuracy of DST in identifying non-susceptibility on AST result) and 95% confidence interval were calculated for each bug-drug combination. Antibiotic Spectrum Index was evaluated at 3 time points to assess change in antibiotic prescribing after availability of DST and AST results.Results496 patients (median age: 51 months, IQR: 7–165 months) with 603 positive blood cultures were included in the final analysis. PPV of DST was ≥96%for most organism-antibiotic pairs (Table). NPV of DST varied substantially across organism-antibiotic pairs and was frequently lower than PPV. The proportion of patients with more narrow spectrum antibiotic orders increased after the DST result and again after the AST result (Figure).TableTest performance of direct susceptibility testing (DST) of clinical isolates from patients with bacteremia to identify organism susceptibility to the noted antibiotic. Positive predictive value measures the ability of a susceptible DST result to predict a susceptible AST result. Negative predict value measures the ability of an intermediate or resistant DST result to predict an intermediate or resistant AST result. *Includes Staphylococcus capitis, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus pettenkoferi, and Staphylococcus warneri. ‡Includes Citrobacter freundii complex, Citrobacter koseri, Enterobacter aerogenes, Enterobacter cloacae complex, Escherichia coli, Escherichia vulneris, Klebsiella oxytoca, Klebseilla pneumoniae, Klebsiella variicola, Pantoea species, Proteus mirabilis, Salmonella species, Salmonella typhi, Serratia liquefaciens, and Serratia marcescens. FigureDistribution of spectrum of antibiotics ordered to treat bacteremia in pediatric patients. Antibiotic spectrum, as measured by the antibiotic spectrum index, is represented in this Sankey diagram on the Y-axis. The height of each group indicates the proportion of patients with an aggregate antibiotic spectrum falling in that category at three time points. The ASI of empiric antibiotics was measured just before the DST result to provide time for a treating physician to settle on an empiric regimen. The ASI with the DST result was measured just before the ASI result. The ASI with the AST result was measured 24 hours after the AST result was available. Green bars indicate the proportion of patients within a group whose ASI remained unchanged between time points. Blue bars indicate the proportion of patients within a group whose ASI decreased, and red bars indicate the proportion of patients whose ASI increased between time points. ConclusionDST is highly accurate at identifying susceptibility to antibiotics for many bug-drug combinations in pediatric blood culture isolates, but its ability to identify non-susceptibility is less robust. The observed spectrum of prescribed antibiotics was narrower after DST results, suggesting some clinicians may be using the result to de-escalate therapy. DST may be a useful low-cost tool for antimicrobial stewardship.Disclosures All Authors: No reported disclosures

Characterization of a vancomycin-resistant Enterococcus faecium isolate and a vancomycin-susceptible E. faecium isolate from the same blood culture.

To characterize two Enterococcus faecium isolates with different resistance phenotypes obtained from the same blood culture. The isolates were identified by MALDI-TOF MS and antimicrobial susceptibility testing (AST) was performed using a VITEK® 2 AST P592 card and Etest. WGS was performed on the MiSeq and MinION sequencer platforms. Core-genome MLST (cgMLST) and seven-loci MLST were performed. Plasmid analysis was performed using S1-PFGE followed by Southern-blot hybridization. Both E. faecium isolates were ST203. AST revealed that one was a vancomycin-resistant E. faecium (VREfm) isolate and the other was a vancomycin-susceptible E. faecium (VSEfm) isolate. The VREfm isolate harboured the vanA gene cluster as part of a Tn1546-type transposon encoded on a 49 kb multireplicon (rep1, rep2 and rep7a) plasmid (pAML0157.1). On the same plasmid, ant(6)-Ia, cat-like and erm(B) were encoded. The VSEfm isolate harboured a rep2 plasmid (pAML0158.1), 12 kb in size, which was present in full length as part of pAML0157.1 from the VREfm isolate. The vanA-encoding pAML0157.1 was a chimera of the rep2 pAML0158.1 and a second DNA segment harbouring vanA, ant(6)-Ia, erm(B) and cat-like, as well as the replicons rep1 and rep7a. By cgMLST analysis, the VREfm and VSEfm isolates were identical. Our results demonstrate that the VREfm and VSEfm blood culture isolates represented ST203 and were identical. The investigated heterogeneous resistance phenotypes resulted from the acquisition or loss of plasmid segments in the enterococcal isolates. These data illustrate that mobile genetic elements may contribute to the spread of vancomycin resistance among enterococci and to the genotypic and phenotypic variation within clonal isolates.

Bloodstream infections and antibiotic sensitivity pattern in intensive care unit.

Bloodstream infection remains one of the most important causes of morbidity and mortality globally, specifically among intensive care unit patients. This prospective observational study included 887 blood culture samples collected cases admitted to intensive care unit suspected of having sepsis. Samples were cultured and evaluated for antimicrobial susceptibility patterns: 202 (22.78%) blood cultures were positive and yielded microbial growth with 132 (14.88%) having mono-microbial growth. Gram-negative bacteria accounted for 45.2% cases, with Escherichia coli being the most common; Gram positives accounted for 43.9% with Staphylococci haemolyticus being most common and 10.9% were fungal isolates. Gram-negative isolates were sensitive to colistin and tigecycline and 77.3% of isolates were extended spectrum beta-lactamase (ESBL) producers. Gram-positive isolates were sensitive to tigecycline, linezolid, vancomycin and teicoplanin with 97.5% being methicillin-resistant Staphylococci (MRSA). Most of the blood culture isolates from critically ill patients in intensive care unit were multidrug-resistant, ESBL producers and MRSA which raises a serious concern about the development of serious antibiotic resistance.

Minimum inhibitory concentration (MIC) of ceftriaxone for blood culture isolates of nalidixic acid resistant Salmonella (NARS) – A 9 year study

Minimum inhibitory concentration (MIC) of ceftriaxone for blood culture isolates of nalidixic acid resistant Salmonella (NARS) – A 9 year study

Diversity of SCCmec elements and spa types in South African Staphylococcus aureus mecA-positive blood culture isolates

BackgroundThe prevalence of Staphylococcus aureus varies depending on the healthcare facility, region and country. To understand its genetic diversity, transmission, dissemination, epidemiology and evolution in a particular geographical location, it is important to understand the similarities and variations in the population being studied. This can be achieved by using various molecular characterisation techniques. This study aimed to provide detailed molecular characterisation of South African mecA-positive S. aureus blood culture isolates by describing the SCCmec types, spa types and to lesser extent, the sequence types obtained from two consecutive national surveillance studies.MethodsS. aureus blood culture isolates from a national laboratory-based and enhanced surveillance programme were identified and antimicrobial susceptibility testing was performed using automated systems. A real-time PCR assay confirmed the presence of the methicillin-resistance determinant, mecA. Conventional PCR assays were used to identify the SCCmec type and spa type, which was subsequently analysed using the Ridom StaphType™ software. Multilocus sequence typing was performed on selected isolates using conventional methods. MRSA clones were defined by their sequence type (ST), SCCmec type and spa type.ResultsA detailed description of findings is reported in this manuscript. SCCmec type III predominated overall followed by type IV. A total of 71 different spa types and 24 novel spa types were observed. Spa type t037 was the most common and predominated throughout followed by t1257. Isolates were multidrug resistant; isolates belonging to all SCCmec types were resistant to most of the antibiotics with the exception of type I; isolates with spa type t045 showed resistance to all antibiotics except vancomycin. The most diverse SCCmec-spa type complex was composed of the SCCmec type IV element and 53 different spa types.ConclusionAlthough ST data was limited, thereby limiting the number of clones that could be identified, the circulating clones were relatively diverse.

Infection Prevalence in Adolescents and Adults With Acute Myeloid Leukemia Treated in an Indian Tertiary Care Center.

PURPOSEInfections remain a major challenge in the treatment of acute myeloid leukemia (AML). Induction-related mortality reported in the literature is approximately < 5% in clinical trials. However, the real-world scenario is different, especially in developing countries, given the high incidence of multidrug-resistant (MDR) organisms, high incidence of fungal pneumonia at baseline, and significant delay before initiation of chemotherapy. We aimed to look at contemporary infections and infection-related mortality and analyze the patterns of infections.MATERIALS AND METHODSThis retrospective study was conducted at a large tertiary care oncology center in India. Patients with newly diagnosed AML who were older than age 15 years, considered fit for intensive therapy, and treated in the general wards of the adult hematolymphoid unit from March 1, 2014, until December 31, 2015, were included.RESULTSOne hundred twenty-one patients were treated during the study period. The most common presenting complaint was fever (85%). The focus of infection at presentation was found in 63% of patients, with respiratory infection being the most common (47%). MDR organisms were isolated in 55% of patients during induction from various foci. Klebsiella pneumoniae was the most common blood culture isolate (42.9%). Fungal pneumonia was diagnosed in 55% of patients during induction despite antifungal prophylaxis. Treatment-related mortality was 10.7% in all phases, with an induction mortality rate of 7.4%. Complete remission was attained in 69% of patients. Of all patients who received induction chemotherapy, 74% completed all three consolidation cycles. The 121 patients were followed up for a median period of 53 months. Four-year event-free survival was 35.8%, and 4-year overall survival was 41.5%.CONCLUSIONInfections and infection-related mortality are major challenges during AML induction. Gram-negative MDR and fungal infections are particularly common in our region.

Use of the BioFire Film Array Blood Culture Identification(BCID) Panel(BioFire Diagnostics, Salt Lake City, Utah) on Pleural Fluid Samples in Pediatric Patients Hospitalized for Community Acquired Pneumonia(CAP)

Abstract Introduction/Objective CAP accounts for approximately 124,000 pediatric hospitalizations annually. Those patients often have received antibiotics prior to admission. Many have concurrent viral infections. Bacterial infections accompanying viral respiratory infections are known to increase morbidity and mortality. Traditional bacterial culture methods are often negative because of previous antibiotic therapy. The BCID, a multiplex polymerase chain reaction(PCR) assay, can identify 19 bacterial pathogens in approximately 90 minutes. It is FDA approved for blood culture isolates. We hypothesized it would detect bacterial pathogens in pleural effusions. Methods BCID panels were done on residual pleural fluid samples from 10 patients with severe community acquired pneumonia during the period 5/2018 – 12/2019. The patients had positive radiographic findings of pneumonia, were inpatients, had intact immune systems by clinical history and had received antibiotic therapy for more than 8 hours before specimen collection. Treatment required 133 inpatient days. 6 of 10 were diagnosed with viral respiratory pathogens. 1 of 9 had a positive blood culture. 1 of 10 had a positive pleural fluid culture. Results 10 of 10 pleural fluid specimens were positive for a pathogen on the BCID panel – 8, Streptococcus pneumoniae, 1, Staphylococcus aureus and I, Streptococcus pyogens. Two of ten had confirmatory positive cultures. Also, one pleural fluid gram stain showed gram positive cocci in chains and clusters. The BCID detected Streptococcus pyogens. Anti Streptolysin O was strongly positive, 964(0 – 70) IU/mL. Conclusion The yield of bacterial culture plummets with previous antibiotic treatment. FDA approved multiplex PCR panels have narrowly defined specimen requirements. That increases the cost and decreases test applicability. Despite a history of appropriate immunizations in the sample population Streptococcus pneumoniae may be prevalent in the complex pediatric pneumonia population. The BCID may be effective at pathogen detection in cases of complex pneumonia where patients have received prior antibiotic treatment.

Trends in Bacteremia Over 2 Decades in the Top End of the Northern Territory of Australia.

Background Information on the local distribution of bloodstream pathogens helps to guide empiric antibiotic selection and can generate hypotheses regarding the effectiveness of infection prevention practices. We assessed trends in bacterial blood culture isolates at Royal Darwin Hospital (RDH) in the Northern Territory of Australia between 1999 and 2019.Methods Species identification was extracted for all blood cultures first registered at RDH. Thirteen organisms were selected for focused analysis. Trends were examined graphically and using univariable linear regression.Results Between 1999 and 2019, 189 577 blood cultures from 65 276 patients were processed at RDH. Overall, 6.72% (12 747/189 577) of blood cultures contained a bacterial pathogen. Staphylococcus aureus was the most common cause of bacteremia during the first decade, with an estimated incidence of 96.6 episodes per 100 000 person-years (py; 95% CI, 72.2–121/100 000 py) in 1999. Since 2009, S. aureus bacteremia has declined markedly, whereas there has been an inexorable rise in Escherichia coli bacteremia (30.1 to 74.7/100 000 py between 1999 and 2019; P < .001), particularly in older adults. Since 2017, E. coli has been more common than S. aureus. Rates of Streptococcus pneumoniae bacteremia have reduced dramatically in children, while Burkholderia pseudomallei remained the fourth most common bloodstream isolate overall.Conclusions The incidence of S. aureus bacteremia, though high by international standards, is declining at RDH, possibly in part due to a sustained focus on both community and hospital infection prevention practices. Gram-negative bacteremia, particularly due to E. coli, is becoming more common, and the trend will likely continue given our aging population.

Nasopharyngeal colonization at birth and the development of early-onset neonatal sepsis

Background Neonatal sepsis is one of the major causes of morbidity and mortality in neonates. Exposure to maternal bacteria during pregnancy or delivery allows for colonization of the normal upper airway. Such bacteria become the major ecological species in the infant. If the colonizing bacteria invade the bloodstream, early-onset neonatal sepsis (EONS) could occur.&#x0D; Objective To evaluate for an association between colonization of the newborn nasopharynx and EONS, as well as for agreement between nasopharyngeal swab culture and blood culture isolate results.&#x0D; Methods This prospective cohort study was conducted in Dr. Wahidin Sudirohusodo General Hospital and Ibnu Sina Hospital, Makassar, South Sulawesi. Nasopharyngeal swab culture was taken within 2 hours of life from newborns who met the inclusion criteria, then they were followed up for signs of EONS. Blood culture was taken from subject with EONS.&#x0D; Results Of the 100 newborns, 69 (69%) had nasopharyngeal bacterial colonization, of whom 5.8% (4/69) experienced EONS. Of the remaining 31 (31%) without colonization, 9.7% (3/31) experienced EONS. There was no significant difference in frequency of EONS between newborns with and without nasopharyngeal colonization. Although Gram-negative bacteria were predominant among colonized newborns, there was no significant difference to numbers of Gram-positive bacteria as a causative agent of EONS. Only one patient with EONS had the same bacterial species in both the nasopharynx and blood culture isolate.&#x0D; Conclusion Newborn nasopharyngeal colonization at birth is not associated with EONS.

National Surveillance of Methicillin-Resistant Staphylococcus aureus Bloodstream Infections in Canadian Acute-Care Hospitals

Background: Bloodstream infections (BSIs) due to methicillin-resistant Staphylococcus aureus (MRSA) are important causes of morbidity and mortality in hospitalized patients. Long-term national MRSA BSI surveillance establishes rates for internal and external comparison and provide insight into epidemiologic, molecular, and resistance trends. Here, we present and discuss National MRSA BSI incidence rates and trends over time in Canadian acute-care hospitals from 2008 to 2018. Methods: The Canadian Nosocomial Infection Surveillance Programme (CNISP) is a collaborative effort of the Association of Medical Microbiology and Infectious Disease Canada and the Public Health Agency of Canada. Since 1995, the CNISP has conducted hospital-based sentinel surveillance of MRSA BSIs. Data were collected using standardized definitions and forms from hospitals that participate in the CNISP (48 hospitals in 2008 to 62 hospitals in 2018). For each MRSA BSI identified, the medical record was reviewed for clinical and demographic information and when possible, 1 blood-culture isolate per patient was submitted to a central laboratory for further molecular characterization and susceptibility testing. Results: From 2008 to 2013, MRSA BSI rates per 10,000 patient days were relatively stable (0.60–0.56). Since 2014, MRSA BSI rates have gradually increased from 0.66 to 1.05 in 2018. Although healthcare-associated (HA) MRSA BSI has shown a minimal increase (0.40 in 2014 to 0.51 in 2018), community-acquired (CA) MRSA BSI has increased by 150%, from 0.20 in 2014 to 0.50 in 2018 (Fig. 1). Laboratory characterization revealed that the proportion of isolates identified as CMRSA 2 (USA 100) decreased each year, from 39% in 2015 to 28% in 2018, while CMRSA 10 (USA 300) has increased from 41% to 47%. Susceptibility testing shows a decrease in clindamycin resistance from 82% in 2013 to 41% in 2018. Conclusions: Over the last decade, ongoing prospective MRSA BSI surveillance has shown relatively stable HA-MRSA rates, while CA-MRSA BSI rates have risen substantially. The proportion of isolates most commonly associated with HA-MRSA BSI (CMRSA2/USA 100) are decreasing and, given that resistance trends are tied to the prevalence of specific epidemic types, a large decrease in clindamycin resistance has been observed. MRSA BSI surveillance has shown a changing pattern in the epidemiology and laboratory characterization of MRSA BSI. The addition of hospitals in later years that may have had higher rates of CA-MRSA BSI could be a confounding factor. Continued comprehensive national surveillance will provide valuable information to address the challenges of infection prevention and control of MRSA BSI in hospitals.Funding: NoneDisclosures: None

Management of Children With Fever at Risk for Pediatric Sepsis: A Prospective Study in Pediatric Emergency Care.

Objective: To study warning signs of serious infections in febrile children presenting to PED, ascertain their risk of having sepsis, and evaluate their management.Design: Prospective observational study.Setting: A single pediatric emergency department (PED).Participants: Febrile children, aged 1 month−16 years, with >= 1 warning signs of sepsis.Interventions and Main outcome measures: Clinical characteristics, including different thresholds for tachycardia and tachypnoea, and their association with (1) delivery of pediatric sepsis 6 (PS6) interventions, (2) final diagnosis of invasive bacterial infection (IBI), (3) the risk for pediatric intensive care unit (PICU) admission, and (4) death.Results: Forty-one percent of 5,156 febrile children had warning signs of sepsis. 1,606 (34%) children had tachypnoea and 1,907 (39%) children had tachycardia when using APLS threshold values. Using the NICE sepsis guidelines thresholds resulted in 1,512 (32%) children having tachypnoea (kappa 0.56) and 2,769 (57%) children having tachycardia (kappa 0.66). Of 1,628 PED visits spanning 1,551 disease episodes, six children (0.4%) had IBI, with one death (0.06%), corresponding with 256 children requiring escalation of care according to sepsis guideline recommendations for each child with IBI. There were five additional PICU admissions (0.4%). 121 (7%) had intravenous antibiotics in PED; 39 children (2%) had an intravenous fluid bolus, inotrope drugs were started in one child. 440 children (27%) were reviewed by a senior clinician. In 4/11 children with IBI or PICU admission or death, PS6 interventions were delivered within 60 min after arriving. 1,062 (65%) visits had no PS6 interventions. Diagnostic performance of vital signs or sepsis criteria for predicting serious illness yielded a large proportion of false positives. Lactataemia was not associated with giving iv fluid boluses (p = 0.19) or presence of serious bacterial infections (p = 0.128).Conclusion: Many febrile children (41%) present with warning signs for sepsis, with only few of them undergoing investigations or treatment for true sepsis. Children with positive isolates in blood or CSF culture presented in a heterogeneous manner, with varying levels of urgency and severity of illness. Delivery of sepsis care can be improved in only a minority of children with IBI or admitted to PICU.