Bacteria In Blood Cultures Research Articles

Increasing resistance rate to carbapenem among blood culture isolates of Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa in a university-affiliated hospital in China, 2004-2011.

The objective of this study is to investigate the profile of antimicrobial resistance of Gram-negative bacteria in blood cultures from 2004-2011. Pathogens from positive blood cultures were subcultured, and identified in the First Affiliated Hospital of Nanjing Medical University from January 2004 to December 2011. The antibiotic resistance pattern was analyzed by WHONET 5.4. A total of 1224 cases of Gram-negative bacterial isolates were documented, accounting for 38.6% of the total pathogens isolated from positive blood cultures in the 8-year period. The isolation rates of Klebsiella pneumoniae and Acinetobacter baumannii increased nearly three times over the same time span. Most Gram-negative bacteria isolates, except the isolates of Pseudomonas aeruginosa, showed a significantly increased resistance rate to cephalosporins (in particular third/fourth generation cephalosporins). Noteworthy, the antimicrobial resistance of K. pneumoniae, A. baumannii and P. aeruginosa isolates to carbapenem (imipenem and meropenem) was significantly increased and the resistant rate to carbapenem was >80.0% in A. baumannii in 2011. The results from PCR detection for carbapenemases were as follows: 82.8% (24/29) isolates of K. pneumoniae carried the kpc-2 gene; only three metallo-beta-lactamase-positive P. aeruginosa isolates were detected; and 93.1% (67/72) A. baumannii isolates were blaOXA-23 positive. The antimicrobial resistance rate of Gram-negative bacteria isolated from blood cultures significantly increased from 2004 to 2011, with significant resistance to the third/fourth generation cephalosporins and carbapenem.

Endocarditis and molecular imaging

Endocarditis and molecular imaging

Frequent occurrence of fever in patients who have undergone endoscopic submucosal dissection for colorectal tumor, but bacteremia is not a significant cause

We examined the incidence of and factors associated with fever, as well as the frequency of bacteremia, in patients who had undergone endoscopic submucosal dissection (ESD) for colorectal tumor. A total of 199 patients (120 male and 79 female) were included. The patients were classified into two groups based on the body temperature on the day after ESD treatment: group A, body temperature <37 °C; and group B, body temperature ≥37 °C. The following factors were analyzed to determine their potential association with post-ESD fever: gender, age, tumor size, form, location, and presence or absence of intraoperative perforation. In addition, blood samples from 50 patients were obtained for blood culture and 16S rRNA gene analysis by polymerase chain reaction. Group A included 106 patients (70 male and 36 female), with a median age of 63 years. Group B included 93 patients (50 male and 43 female), with a median age of 70 years. The incidence of post-ESD fever in the entire cohort was 46.7%. Univariate analysis based on comparison between groups A and B showed that the following factors were significantly associated with post-ESD fever: age [mean ± standard deviation (SD)], 64.5 ± 9.2 versus 68.5 ± 10.8 years, P = 0.006; and tumor size (mean ± SD) 30.6 ± 10.8 versus 39.1 ± 16.6 mm, P < 0.001. Logistic regression analysis for post-ESD fever also found that age {odds ratio 1.04 (95% CI [1.01-1.07], P = 0.009)} and lesion size {odds ratio 1.05 (95% CI [1.03-1.08], P = 0.0002)} were closely associated with post-ESD fever. Of the 50 patients who had blood samples cultured and 16S rRNA gene analyzed, bacteria in blood culture and the 16S rRNA gene were not detectable in any of the samples from the 50 patients. This study indicated that older patients and patients with large tumors were more likely to develop post-ESD fever, but there was a low probability that bacteremia was the cause of fever.

Effect of Sodium Citrate on Growth of Bacteria in Blood Culture

Background: This study compared the growth of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus pneumoniae, and Haemophilus influenzae in blood culture bottles containing anticoagulants, sodium polyanethol sulfonate (SPS) and sodium citrate. Methods: One hundred and fifty colony forming units of five different bacterial species were inoculated into standard aerobic (SA) and standard anaerobic (SN) bottles and were combined with 5 mL of human blood in solution with SPS or sodium citrate. Time to detection (TTD) was then monitored using the BacT/ Alert 3D system (bioMerieux Inc.). Results: Compared to the bacteria-only controls, cultures containing S. aureus, E. coli, P. aeruginosa, and S. pneumoniae plus SPS blood or citrated blood trended toward reduced TTD in both SA and SN bottles; however, there was no significant difference in TTD between SPS and sodium citrate anticoagulant. Although H. influenzae showed a remarkable difference in TTD between SPS (SA 14.8 h, SN 15.0 h) and sodium citrate (SA 23.5 h, SN 18.3 h), this difference was not statistically significant (P=0.10). Conclusion: Addition of blood enhanced growth of bacteria. All experimental bacteria except H. influenzae showed similar TTD in SPS blood and citrated blood. These results support the usefulness of sodium citrate anticoagulant for artificial inoculation in blood culture bottles. (Ann Clin Microbiol 2013;16: 168-173)

Arterial bicarbonate may be a useful indicator of inadequate cortisol response in children with catecholamine resistant septic shock

To study the clinical and biochemical parameters that can predict cortisol insufficiency in children with septic shock. prospective, observational study. Tertiary health-care center. Fifty children admitted with the catecholamine resistant septic shock to a tertiary health-care center. At the time of hospitalization all patients underwent detailed clinical evaluation including, history and physical examination, evaluation with the complete blood count, serum cortisol, renal function tests, liver function tests, prothrombin time activated partial thromboplastin time, arterial blood gas analysis, urine analysis, chest roentgenogram, ultrasonography of the abdomen and chest, urine, and blood culture for bacteria and fungi. Out of 50 children with the catecholamine resistant septic shock, seven had adrenal insufficiency (serum cortisol <18 μg/dl). Of all parameters studied, only arterial bicarbonate at the time of admission to intensive care predicted adrenal insufficiency. On Receptor operative characteristic curve analysis, a bicarbonate level of 10.9 mEq/L had the best accuracy to predict adrenal insufficiency. Arterial bicarbonate may be used as a rapid test for provisional identification of adrenal insufficiency among children with the catecholamine resistant septic shock.

Saponin promotes rapid identification and antimicrobial susceptibility profiling of Gram-positive and Gram-negative bacteria in blood cultures with the Vitek 2 system

The rapid identification and antimicrobial susceptibility testing (AST) of bacteria in clinical blood cultures is crucial to optimise antimicrobial therapy. A previous study involving small sample numbers revealed that the addition of saponin to blood cultures, further referred to as the new method, shortened considerably the turn-around time for the identification and AST of Gram-positive cocci as compared to the current method involving an overnight subculture. Here, we extend previous results and compare the identification and AST of blood cultures containing Gram-negative bacilli by the new and current methods. The identification and AST of 121 Gram-positive and 109 Gram-negative bacteria in clinical monomicrobial blood cultures by the new and current methods and, in the case of Gram-negative bacilli, by direct (no additions) inoculation into an automated system (rapid method) was assessed using the Vitek 2 system. Discrepancies between the results obtained with the different methods were solved by manual methods. The new method correctly identified 88 % of Gram-positive and 98 % of Gram-negative bacteria, and the rapid method correctly identified 94 % of Gram-negative bacteria. The AST for all antimicrobials by the new method were concordant with the current method for 55 % and correct for an additional 9 % of Gram-positive bacteria, and concordant with the current method for 62 % and correct for an additional 21 % of Gram-negative bacilli. The AST by the rapid method was concordant with the current method for 62 % and correct for an additional 12 % of Gram-negative bacilli. Together, saponin-treated monomicrobial blood cultures allow rapid and reliable identification and AST of Gram-positive and Gram-negative bacteria.

Incidence of oral indigenous bacteria in causative strains isolated from blood cultures in 759 laboratory-confirmed cases of bacteremia

Abstract Background: The incidence of oral indigenous bacteria in cases of bacteremia has been reported in only a few studies. We investigated the annual incidence of oral indigenous bacteria isolated in blood cultures from patients with bacteremia and call into consideration the impact of oral health measures implemented at our facility. Methods: In the period from 2001 to 2006, 759 laboratory-confirmed cases of bacteremia were reported and subsequently analyzed in this study. The incidences of the causative strain and oral indigenous bacteria in blood cultures were studied by year. Results: In 759 cases of bacteremia, oral streptococci were noted in 14 (1.8%), and anaerobic bacteria were noted in 9 (1.2%). The population of microorganisms did not change significantly during the study period. Conclusions: In a previous report, oral streptococci accounted for 3.8% of those under investigation. In this study, the incidence of oral streptococci was significantly low, 1.8% specifically. A focus on oral health care at our hospital may account for a reduced incidence of oral streptococci bacteremia.

Amebic Colitis and Liver Abscess Complicated by High Serum Procalcitonin in Acute Myeloid Leukemia

We present a case of amebic colitis and liver abscess complicated by acute myeloid leukemia (AML) with high serum procalcitonin (PCT). A 61-year-old Japanese man seen at our hospital for severe diarrhea and high fever was found to have multiple ulcers in the transverse and sigmoid colon and rectum by colonoscopy and biopsies were conducted. Immature leukocytes with mild anemia and thrombocytopenia were seen in peripheral blood, necessitating bone marrow aspiration and biopsy that yielded a diagnosis of AML (FAB M4Eo). Serum C-reactive protein and PCT were extremely elevated. Blood cultures for bacteria and fungi were negative. Multiple low-density areas in the liver were found in abdominal computed tomography. Histological colon biopsy findings revealed amebic colitis, strongly suggesting amebic liver abscess. Metronidazole treatment was initiated for amebiasis and subsequent standard chemotherapy for AML was followed after fever was lowered. Hematological and cytogenetic CR was maintained with good clinical condition. Few case reports have been published in Japan to date on amebic colitis and liver abscess complicated by AML and no reports have been made on PCT elevation caused by amebiasis. In conclusion, differential diagnosis of amebiasis is necessary in addition to that of bacterial or fungal infection in serum PCT elevation.

Escherichia coli bacteraemia in a pediatric emergency service (1995-2010)

Some authors reported an increase in relative incidence of E. coli bacteraemia in recent years. E. coli has been the third most frequently isolated bacteria in blood cultures at our emergency service between 1995 and 2009. To analyse trends, clinical, laboratory and microbiological data of E. coli bacteraemia in a level 3 pediatric hospital, in the last 16 years. Retrospective analysis of cases with positive blood cultures for E. coli between 1995-2010. Nosocomial infections were excluded. E. coli was identified in 32 children (19 boys); 15 cases (47%) were diagnosed in the second half of the study. The median age was 1,5 months: 13 (41%) were neonates, 23 (72%) were less than three months of age and 29 (91%) were less than 12 months. Fever was the most common symptom, present in 29 children (91%). In the neonatal period the median leukocyte count was 12,2 x 103/mL and median C reactive protein was 13 mg/dL. Beyond the first month of age, the median leukocyte count was 16,7 x 103/mL and median C reactive protein was 10 mg/dL. The diagnosis were: acute pyelonephritis (57%), sepsis (13%), urosepsis and meningitis (9% each), occult bacteremia (6%), cholangitis and appendicitis (3% each). Eight of 21 acute pyelonephritis were diagnosed in the neonatal period. One child died (sepsis) and two had brain abscesses after meningitis. Resistances were: 24% to ampicillin, 12% to amoxicillin+clavulanate, 18% to cefalotin, 0% to cefotaxime and aminoglycosides. Resistances were higher in the neonatal period. We did not see an increase of community-acquired E. coli bacteraemia over the last 16 years in our hospital. Infections occurred mainly in the neonatal period and first three months of life and the most frequent diagnosis was acute pyelonephritis. Leukocytosis is not always present, particularly in the neonatal period. A quarter of the E. coli was resistant to ampicillin. The outcome was favorable in most children and one died of sepsis.

PCR Identification of Bacteria in Blood Culture Does Not Fit the Daily Workflow of a Routine Microbiology Laboratory

We have evaluated the GenoType blood culture assay (Hain Lifescience, Nehren, Germany) for the identification of bacteria in 233 positive blood cultures and assessed its suitability in the workflow of a routine microbiology laboratory. In 68/233 (29.2%) samples, the culture result could not be confirmed by the GenoType assay due to a lack of primers in the test, multiple organisms in the sample, or inconsistency with respect to the identification by culture. Although the GenoType blood culture assay gives satisfactory results for bacteria for which primers are available, there are difficulties in applying the test in the routine microbiology laboratory.

Direct identification of bacteria in blood culture by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: a new methodological approach

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently been demonstrated to be a powerful tool for the rapid identification of bacteria from growing colonies. In order to speed up the identification of bacteria, several authors have evaluated the usefulness of this MALDI-TOF MS technology for the direct and quick identification bacteria from positive blood cultures. The results obtained so far have been encouraging but have also shown some limitations, mainly related to the bacterial growth and to the presence of interference substances belonging to the blood cultures. In this paper, we present a new methodological approach that we have developed to overcome these limitations, based mainly on an enrichment of the sample into a growing medium before the extraction process, prior to mass spectrometric analysis. The proposed method shows important advantages for the identification of bacterial strains, yielding an increased identification score, which gives higher confidence in the results.

Novel Electrical Method for Early Detection of Viable Bacteria in Blood Cultures

We present a novel electrical method for detecting viable bacteria in blood cultures that is 4 to 10 times faster than continuous monitoring blood culture systems (CMBCS) like the Bactec system. Proliferating bacteria are detected via an increase in the bulk capacitance of suspensions, and the threshold concentration for detection is ∼ 10(4) CFU/ml (compared to ∼ 10(8) CFU/ml for the Bactec system).

A specific serum IgA antibody discriminates pneumonia from colonization state in patients with Pseudomonas aeruginosa in sputum culture

We attempted to develop a new specific antibody detection method for discriminating infection state from colonization state in hospitalized immunocompromised patients with a positive sputum culture for Pseudomonas aeruginosa. Serum samples from 65 patients with P. aeruginosa in sputum culture (total PA patients), including 24 patients with P. aeruginosa-related pulmonary infections (PA infection group) and 21 patients without pulmonary infections (PA colonization group), as well as samples from 20 patients positive for other bacteria in blood culture (non-PA infection group) and 38 healthy controls were examined and compared for IgG and IgA anti-P. aeruginosa antibodies by a newly developed enzyme-linked immunosorbent assay (ELISA). Both IgG and IgA antibody ELISA showed satisfactory reproducibility with low coefficient of variation (CV) percent, and western blotting analysis showed two protein bands as the corresponding antigens common to both antibodies. The serum levels of both antibodies in all the PA patients were higher than those in the healthy controls with high significance (p<0.0001). The PA infection group showed significantly higher mean levels of both IgG and IgA class antibodies than the PA colonization group, non-PA infection group and healthy controls (each, p<0.0001). In receiver operating characteristic (ROC) curves analysis to differentiate between total PA infections and the PA colonization group, the area under curve (AUC) of the IgA antibody (0.848) was significantly larger than the AUC of the IgG antibody (0.677) (p=0.019). At the optimal IgA antibody cutoff value for differentiation of 1.37units/mL, the sensitivity and specificity of IgA anti-P. aeruginosa ELISA were 83.3% and 85.7%, respectively. These findings suggest that IgA antibody ELISA, rather than IgG antibody ELISA, may be useful for differentiating P. aeruginosa-related pneumonia from latent colonization in immunocompromised patients with a positive sputum culture.

Safe and feasible outpatient treatment following induction and consolidation chemotherapy for patients with acute leukaemia

Traditionally, patients with acute leukaemia are admitted to hospital during chemotherapy-induced pancytopenia, although a few recent reports have reported the feasibility and safety of outpatient treatment. We have developed an outpatient treatment programme for patients with acute leukaemia incorporating comprehensive patient education for self-care management at home during pancytopenia and involvement of patients in care of their tunnelled central venous catheter (CVC). During neutropenia, patients are treated with prophylactic ciprofloxacine, amoxicillin/clavulanic acid and fluconazole. Herein, we report the results of outpatient treatment of 60 patients with acute leukaemia (54 with acute myeloid leukaemia) followed prospectively in the period from March 2004 to 2007. After induction chemotherapy, outpatient treatment was possible after 48 of 73 induction courses, with no readmission in 19 of these (40%). A total of 129 consolidation courses were administered with outpatient treatment following 116 of these, with no readmission in 69 (59%). The median number of days spent at home with neutrophils below 0.5 x 10(9)/L was 8 d per course following induction and 12 d following consolidation chemotherapy. The predominant cause of readmission was neutropenic fever, in most instances of unknown origin. Coagulase-negative staphylococci and Enterococcus faecium were the most frequently identified bacteria in blood cultures, whereas only four positive blood cultures with multiresistant Escherichia coli were identified in the entire patient cohort, the latter exclusively observed in patients receiving antibiotic prophylaxis. The majority of the patients were able to take care of their CVC including change in dressing and heparin flushing. There were 12 CVC-related infections. There were no treatment-related deaths. We conclude that outpatient treatment of patients with acute leukaemia is feasible and safe.

Uso de la técnica de hibridación fluorescente in situ para la identificación rápida de staphylococcus aureus en hemocultivos

Background: The technique of reference for the detection of bacteriemia is the blood culture. One of the most frequent bacteria responsible of bacteriemia is Staphylococcus aureus (SAU). The presence of Gram positive cocci (CGPR), in blood culture give the suspicious of bacteriemia, although the relevance of the finding depends on the correct identification of the microorganism. The definitive typification it demands from 24 to 48 hours. The technique of fluorescent in situ hybridization (FISH), is a rapid method for the identification of bacteria in blood culture. Aims: The aims of this work was to establish the FISH technique directed to the 16S RNA of SAU in samples of blood cultures with CGPR to the Gram staining, to determine the concordance with the method of reference, and to evaluate the possibility to use as standard method in the laboratory of microbiology. Material and Methods: The blood cultures analyzed in the Laboratory of Microbiology of the Hospital Privado Cordoba from 01.01.2009 to 31.12.09 were included in this study. To each positive blood culture which showed CGPR was applied simultaneously biochemical identification and FISH. Results: From 496 positive samples, 32 showed CGPR, 24 of them were identified as SAU. A concordance of 100% (IC95% 99 to 100) between both methods of diagnosis, with a value of k&lt;0.01 was observed. Discussion: The excellent concordance opens the prospect for a study in order to determine the predictive value of FISH, its sensibility and specificity. Furthermore, it will be possible to evaluate its clinical impact being incorporated in a laboratory of clinical bacteriology.

Rapid identification and antimicrobial susceptibility profiling of Gram-positive cocci in blood cultures with the Vitek 2 system

Rapid identification and antimicrobial susceptibility profiling of the bacteria in blood cultures can result in clinical and financial benefits. Addition of saponin to the fluid from blood culture bottles promotes the recovery of the bacteria and thus may shorten the turnaround time of the microbiological analyses. In this study we compared the identification and susceptibility profiles of saponin-treated and untreated (standard method) blood cultures monomicrobial for Gram-positive cocci using Vitek 2. We concordantly identified 49 (89%) of 55 monobacterial cultures using the results with the standard method as reference. Complete categorical agreement between the susceptibility profiles with the new and the standard method was found for 26 (53%) of 49 isolates, while discrepancies were seen for 23 (47%) cultures. E-tests indicated that the new method resulted in a correct susceptibility profile for 8 (35%) of these 23 blood cultures. Therefore, 34 (69%) of 49 cultures showed a concordant/correct susceptibility profile for all antimicrobials with an overall error rate of 2.3%. Thus, addition of saponin to the fluid from blood culture bottles of the Bactec 9240 leads to the rapid (results available ≥12 hours earlier) and reliable identification and susceptibility profiling of Gram-positive cocci in blood cultures with Vitek 2.

Clinical Reasoning: A 35-year-old man with a right hemiplegia and a cerebral mass

A 35-year-old man presented with progressive right face, arm, and leg weakness, and diffuse headache. He lived in rural northwest Argentina. He had a past medical history of sexually transmitted diseases. On examination, he was alert and fully oriented, and had a right hemiparesis with hyperreflexia and an extensor plantar reflex. Apart from low grade fever, the rest of the physical examination was unremarkable. The complete blood count revealed leukopenia (3,300 leukocytes/mL); renal function, liver tests, electrolytes, erythrocyte sedimentation rate, and glucose level were normal. He tested positive for HIV with a CD4 count of 18 cells/mm3 and viral load of 133,400 copies/mm3. Brain CT showed a nonenhancing left temporoparietal lesion with surrounding edema and midline shift. ### Questions for consideration: The patient was started on empirical treatment for toxoplasmosis without clinical improvement. A brain MRI with gadolinium performed days later showed a left temporoparietal mass with a ring-like enhancement pattern and marked perilesional edema (figure). Serologies for hepatitis B virus, hepatitis C virus, VDRL, and Toxoplasma (immunoglobulin G, immunoglobulin M, and immunoglobulin A subtypes) were negative. Blood cultures for bacteria, fungi, and mycobacteria were also negative. Since the patient lived in an endemic area, a search for Chagas disease was performed. The serology confirmed chronic Chagas disease (both indirect immunofluorescence and indirect …

Identification of pathogenic bacteria in blood cultures: Comparison between conventional and PCR methods

Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Acinetobacter baumanii, and Klebsiella pneumoniae were found to be the most prevalent bacteremia-causing bacteria in a survey in a medical center. A PCR method for identification of these five most common pathogens in blood cultures was developed. A unique sequence was chosen for each pathogen and used for primer design. Sixty-one blood samples (from hospitalized patients) in which bacterial growth was detected were processed in parallel by conventional microbiological methods and by the PCR method. The results obtained by PCR were identical to those obtained by conventional methods in 93.4% of the cases. PCR failed to identify bacteria which were found conventionally in only 6.6% of the cases (mostly bacteria not included in the PCR cassette). Another group of eighty-eight blood samples from patients were processed immediately upon their arrival at the laboratory by taking aliquots for the PCR method. The blood sample bottles were processed in parallel by conventional methods. In 78.4% of the cases the results of both methods were identical. In 12.5% of the cases, PCR afforded identification of bacteria but conventional methods showed no bacteria in the sample. On the other hand, PCR afforded 9.1% negative results while conventional methods identified bacteria not included in the PCR cassette. It is concluded that the molecular method appears to be a specific and precise method for identifying pathogenic bacteria in blood samples.

Fatal Algaemia in Patient with Chronic Lymphocytic Leukemia

Fatal Algaemia in Patient with Chronic Lymphocytic Leukemia

Identification of oral bacteria in blood cultures by conventional versus molecular methods

The purpose of this study was to compare two different methods of identifying oral bacteria from blood samples after dental extractions. Blood cultures were taken before, during, and after a single tooth extraction in 30 subjects and cultured using aerobic and anaerobic Bactec media. Positive cultures from 22 subjects were subcultured on selective and nonselective media, resulting in 58 isolates. Bacterial identification was performed by biochemical analysis and sequence analysis of 16S rRNA gene. Of the 58 isolates, only 10 (17%) were the same species by both methods. Thirty-two (55%) belonged to the same genus but different species, and 16 (28%) showed no correlation at all. There were 31 and 40 diverse species by the biochemical and the sequencing methods, respectively. Streptococci were the dominant species. DNA sequencing results in more accurate identification and a more diverse population of bacteria from bacteremia following dental extractions.