Routine Blood Cultures Research Articles

末梢血白血球中の細菌検出キット (in situ hybridization法) の菌検出に対する有用性

We studied the clinical utility of in situ hybridization (Hybrisep) in diagnosing respiratory infection and/ or sepsis. Peripheral blood was taken from patients with respiratory infections and suspected sepsis for both routine blood culture and in situ hybridization, and focal samples including sputum, bronchoalveolar lavage, and central and thoracic catheter, were simultaneously examined for bacterial culture. Specimens numbered 46. The clinical diagnosis was 20 cases of septicemia, with 26 specimens diagnosed as respiratory infectious diseases including hospital-acquired pneumonia and pleurisy. Positive cases of in situ hybridization were seen in 19 specimens (41.3%) in all specimens, significantly higher than that in blood culture (17.4%). Respiratory infection showed a high positive rate in in situ hybridization. Interestingly, the bacterial pathogen detected by in situ hybridization was not always consistent with that taken from focal samples. Whether the pathogen isolated by in situ hybridization is accurate etiologically or diagnostically remains unknown, but our findings suggest a polymicrobial infection in patients with hospital-acquired respiratory infections. In situ hybridization thus provides important information on the etiological pathogen in different infectious diseases.

Clinical Features And Correlates Of Bacteremia Among Urban Minority New Yorkers Hospitalized With Community Acquired Pneumonia

Background: Pneumonia mortality, incidence and rates of bacteremia related to CAP varies among US minority compared to White Americans. However, information on clinical features, risk for bacteremia and hospitalization costs due to CAP among minority subjects is lacking. Methods: We studied clinical features of CAP, factors associated with bacteremia due to CAP, length of stay among adult hospitalized inner city Hispanic and African American New Yorkers. Results: Among 697 study subjects of whom 92% were of Hispanic and African American origin, 69 (9.9%) were found to have a positive blood culture. Bacteremia related to CAP was noted only in 35 (5%) subjects. Nine subjects (1.3 %) had bacteremia unrelated to CAP during hospitalization. 25 positive blood cultures (3.6%) were considered as skin contaminants by the treating clinicians. None of the co-morbidity or outcome variables were associated with CAP bacteremia except HIV positive status (OR 2.97 95% CI 1.2 – 7.3). CAP bacteremia group were at higher odds for abnormal vital signs, serum chemistry and hematological parameters. The length of stay (LOS) was increased due to positive blood cultures, especially in those with non-CAP pathogens (median 14 days) and contaminants (9 days) compared to CAP pathogens (5 days) (p < 0.05). In the sub-group analysis, Hispanics with CAP were noted to be older and have higher odds of lung disease compared to non-Hispanics. HIV infected subjects were noted to be younger and HIV positive subjects with CAP bacteremia were at higher odds to present with consolidation on chest x-ray compared to other HIV positive controls. Conclusions: As noted in other populations, routine blood cultures among hospitalized inner city minority CAP patients are associated with low yield for CAP pathogens from routine blood cultures drawn during initial evaluation and management of CAP. Also, bacteremia with CAP pathogens is unrelated to any co-morbidity or outcome except HIV positive status, abnormal clinical sings and selected lab abnormalities in this population. Minority patients who are HIV positive and have radiographic consolidation, may be at higher odds to have positive cultures with CAP organisms. Further, contaminant blood cultures from routine blood drawing may increase length of stay and therefore impact health care expenditure in CAP patients significantly. Therefore, minority subjects with clinical risks only as described may benefit from blood culture tests upon hospitalization for CAP.

Development of a real-time Staphylococcus aureus and MRSA (SAM-) PCR for routine blood culture

The notification of “Gram-positive cocci, possibly staphylococcus” in a blood culture drawn from a seriously ill patient is responsible for a large amount of vancomycin prescribing in institutions where methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of bacteraemia. A duplex real-time TaqMan polymerase chain reaction targeting the species-specific nuc gene, and the mecA gene encoding methicillin-resistance, was developed as a tool for rapid identification and detection of S. aureus and methicillin-resistance, and optimised for immediate as-needs testing. Three different DNA extraction methods achieved varying DNA quality, with PCR inhibition the main problem. Serial blood cultures ( n = 120) identified as possible staphylococci on Gram stain from our clinical laboratory were examined. There was one false negative result for a methicillin-resistant Staphylococcus epidermidis, which was positive on repeat testing, and one false negative result due to DNA extraction failure for MRSA from peritoneal dialysate inoculated into blood culture medium. Sensitivity and specificity of 97% and 100%, respectively, were obtained for mecA; and sensitivity and specificity of 98% and 100%, respectively, for nuc. Detection of slow-growing coagulase-negative staphylococci as co-infecting strains may be reduced. The assay quickly and reliably identified S. aureus in mixed infection, and identified methicillin resistance in both S. epidermidis and S. aureus strains.

Disseminated Nontuberculous Mycobacterial Infections in Sickle Cell Anemia Patients

Nontuberculous mycobacteria (NTM) are ubiquitous in nature and have been implicated in skin/soft-tissue, pulmonary, middle ear, bone, and surgical/traumatic wound infections. Disseminated disease occurs infrequently and almost exclusively in the immunocompromised. We describe the first 2 reported cases of disseminated Mycobacterium fortuitum infection in teenagers with sickle hemoglobinopathy. Both had central venous catheters (CVCs), frequent admissions for vaso-occlusive painful episode and received hydroxyurea. Diagnosis was confirmed by multiple positive blood cultures and pulmonary dissemination occurred in both. Both had successful treatment after CVC removal and combination drug therapy. Positive cultures persisted in 1 patient due to drug resistance emphasizing the need for accurate susceptibility data. NTM infection should be added to the list of pathogens in sickle cell patients with CVCs and fever. Investigation for disseminated disease should be undertaken based on clinical signs and symptoms. Although some routine blood culture systems can identify NTM, specific mycobacterial blood culture is optimal. Removal of involved CVCs is essential and treatment of NTM must be guided by susceptibilities. As dissemination almost always occurs in those with impaired cellular immunity, human immunodeficiency virus testing should be performed. Hydroxyurea may be a risk factor for dissemination and needs further evaluation.

Role of routine blood cultures in detecting unapparent infections during continuous renal replacement therapy

Continuous renal replacement therapy (CRRT) is frequently employed in the management of renal failure in unstable intensive care patients. At some centers, blood cultures are performed routinely while on CRRT to monitor for occult bacteremia. We questioned the role of routine blood cultures (RBC) in diagnosing underlying infections in these often afebrile patients. Retrospective cohort study (1998-2003). Medical, surgical and pediatric intensive care units in a tertiary care teaching hospital. METHODS/MEASUREMENTS: We undertook a retrospective chart review of all 101 episodes of CRRT performed in our hospital since 1998. The primary endpoint of the study was the number of positive cultures that changed patient management. For each positive result, documented infection and parameters of sepsis were noted. There were 101 treatments of CRRT in 98 patients. A total of 698 routine RBC bottles were drawn, a mean of 7.2+/-7 per patient; of those, 29 (4%) were positive in 17patients, documenting 11 bacteremias. Six positive cultures represented contaminants. In all but one case, infection was known or signs of sepsis were present prior to receipt of the culture result. For patients on CRRT, RBC are rarely positive, and do not detect occult infection in the absence of clinical evidence of infection for the majority of patients. Because routine cultures utilize significant resources, and can result in false-positive results, RBC should not be performed in these patients. Careful clinical monitoring, with blood cultures performed at the first clinical suggestion of an infection, should detect all clinically relevant infections.

Broad‐range polymerase chain reaction for the diagnosis of Bartonella henselae endocarditis

We present a case of subacute bacterial endocarditis in a 10-year-old girl with Di-George syndrome, congenital heart disease, and mild immunodeficiency. She was afebrile at initial presentation but was found to have massive splenomegaly, and signs of congestive heart failure. No causative organism could be identified on routine blood and tissue cultures. A detailed clinical history revealed a history that she had been scratched by a cat and developed intermittant fevers over 3 months. Bartonella henselae was identified by broad-range 16S r-DNA polymerase chain reaction on valvular tissue specimens.

Infective Endocarditis Caused by Fastidious Oro-Pharyngeal HACEK Micro-Organisms

Many species of micro-organisms have been implicated as causative agents in infective endocarditis (IE). Streptococci and staphylococci are recognized as the more common pathogens in IE, but in contrast to them there are the less common and easily overlooked fastidious gram-negative oropharyngeal species collectively grouped as the HACEK organisms: Haemophilus parainfluenzae, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae. They are common commensal colonizers of the oropharynx including the periodontal apparatus and they are difficult to detect in routine blood cultures.

Emerging Data Indicating that Extended Incubation of Blood Cultures Has Little Clinical Value

terium avium complex isolates recovered from a patient with AIDS and recovery of 1 Legionella species, all of which were detected using the lysis-centrifugation method) among 215 patients for whom the very extensive special protocol was used. During the same period, 24 HACEK bacteria were detected in ∼14,000 routine blood cultures, all of which were processed in accordance with the laboratory’s standard 5-day incubation protocol. Potential limitations of this study are that the data were generated from a single institution and that the observations may apply to only one of the commercially-available CMBCSs (Bactec; BD Diagnostic Systems). Accordingly, it could be argued that the findings cannot be generalized to other health care centers or other blood culture systems. However, there are emerging data from

Intravenous Polyclonal Immunoglobulin Administration to Sepsis Syndrome Patients: A Prospective Study in a Pediatric Intensive Care Unit

Life-threatening infections account for about 25 per cent of children requiring admission to pediatric intensive care units (PICU). The results of the use of polyclonal intravenous immunoglobulins as an adjuvant in pediatric sepsis syndrome therapy are conflicting. A prospective study of 100 sepsis syndrome PICU patients aged 1-24 months and divided into two matching groups (septic cases and control, 50 patients each) was performed. All patients were treated according to the routine protocol PICU therapy. Only the cases group received, in addition, polyclonal IVIG (Pentaglobin, Biotest) in a dose of 400 mg/kg for 3 days. All cases were evaluated for PRISM III score 8 h after admission; routine blood, urine, stool and cerebrospinal fluid (whenever appropriate) culture. Daily laboratory examination (blood gases, electrolytes, liver and renal functions, complete blood picture and C-reactive protein) were performed for the first 5 days. Blood samples were obtained for evaluation of tumor necrosis factor-alpha (TNF-alpha) daily for the first 5 days. Referral site (ward or casuality), length of PICU stay (LOS) and outcome (discharged or deceased), the number and percentage of cases who progressed to complications were recorded. Results showed that group I had a significantly higher percentage of discharged cases (72 per cent vs. 44 per cent), significantly shorter LOS (6.1 days vs. 9.1 days), and a significantly lower percentage of progress to complications (8 per cent vs. 32 per cent) especially disseminated intravascular coagulation (4 per cent vs. 24 per cent). TNF-alpha was significantly reduced among septic cases on discharge (2.24 vs. 3.6 mg/dl, p<0.001). A multiple logistic regression model revealed that treatment with IVIG, LOS, severity of sepsis and lymphocyte percentage (L per cent) on admission were significant predictors for survival. In summary the study revealed that the use of polyclonal IVIG among PICU sepsis syndrome showed a significant reduction in mortality, LOS and less progress to complications. A multicenter study is recommended to confirm these results.

Role of 99mTc Sulesomab in the diagnosis of prosthetic joint infections

Investigation of suspected infection in prosthetic joint replacements is a difficult orthopaedic problem with important therapeutic implications. We retrospectively analysed the results of 38 patients referred with a clinical suspicion of bone or joint infections. Referrals were made for suspected infection of prosthetic hip joints (17), total knee replacements (13), total elbow replacements (4) and total shoulder replacements (4). Sulesomab imaging was done with 650 MBq of 99mTc Sulesomab. The scintigraphic diagnosis was compared with the final clinical diagnosis and information collected from routine blood tests (erythrocyte sedimentation rate, C-reactive protein and full blood count), plain radiographs, appropriate microbiology, culture and/or histology where available. The final diagnosis was determined by conclusive microbiology, culture and/or histology, intra-operative findings, aspiration, complementary investigations like computed tomography/magnetic resonance imaging and long-term clinical follow-up. The overall sensitivity was 90.90% and specificity 81.48%. The individual sensitivity and specificity of each category were compared. Knee prostheses showed better sensitivity and specificity compared to that for hip prostheses. 99mTc Sulesomab seems to be useful in excluding infection rather than confirming it, with a high negative predictive value (95.65%).

Direct Identification of Gram-Positive Cocci from Routine Blood Cultures by Using AccuProbe Tests

Rapid and reliable identification of bacteria directly from blood cultures is important in clinical practice to guide appropriate antibiotic therapy. In this study, the performance of the AccuProbe (Gen-Probe, Inc., San Diego, Calif.) in direct identification of Staphylococcus aureus, Streptococcus pneumoniae, enterococci, and group A and B streptococci from positive blood culture bottles was evaluated by using 6-year routine clinical laboratory blood culture material from Paijat-Hame Central Hospital, Lahti, Finland. With the enterococcal and group A and B streptococcal probes, the diagnostic performance of the test was excellent at a cutoff value of 50,000 relative light units (RLU) as recommended by the manufacturer. However, with the S. aureus probe, although the specificity was very high (99.8%), the sensitivity was low (72.4%). To improve the clinical usability of the direct AccuProbe identification, optimal cutoff values for the individual AccuProbe tests were defined by using receiver-operating characteristic analysis. Consequently, cutoff values for S. aureus and S. pneumoniae tests were adjusted to 30,000 RLU and for enterococci and to 55,000 RLU for group A and B streptococci. With these adjustments, the performance of the AccuProbe tests, especially that for S. aureus, was significantly improved.

Opportunistic infections in hospitalized HIV-infected adults in Ho Chi Minh City, Vietnam: a cross-sectional study

The HIV epidemic is emerging rapidly in Vietnam. We studied the prevalence of opportunistic infections by performing clinical and microbiological investigations in 100 hospitalized HIV-infected adults in Ho Cho Minh City, Vietnam. The median CD4 count was 20 cells/mm(3) and in-hospital mortality was 28%. The most frequent diagnoses were oral candidiasis (54), tuberculosis (37), wasting syndrome (34), lower respiratory tract infection (13), cryptococcosis (9), and penicilliosis (7). Bacterial (other than tuberculosis) and parasitic infections were uncommon. Regional differences should be considered when deciding which diagnostic procedures and prophylactic measures to implement. In Vietnam, routine mycobacterial blood cultures do not provide greater yield than chest radiography and sputum and lymph node aspirate smears. Prophylactic trimethoprim/sulphamethoxazole against Pneumocystis jiroveci pneumonia may confer little benefit, and high rates of isoniazid resistance may affect the efficacy and feasibility of tuberculosis chemoprophylaxis. However, the usefulness of itraconazole prophylaxis for cryptococcosis and penicilliosis merits further consideration.

Routine Microbiological Screening in Septic Patients in a Cardiac Surgical Intensive Care Unit

Introduction: Patients in a surgical intensive care unit (ICU) have a high incidence of nosocomial infections which often lead to septic shock and death. Since specific antibiotic treatment is often difficult, it is recommended that routine nose/throat swabs be obtained in order to have a better idea of the causative agent when a systemic inflammatory response occurs in a given patient. Materials and Methods: In 1435 patients in a cardiac surgical ICU, routine nose/throat swabs were taken thrice a week and tested for microorganisms and systemic inflammation. Blood cultures were also obtained. Antibiotic treatment was given to cover the microbes from the nose/throat swabs. Alternatively, an empirical antibiotic therapy was given to patients whose swabs had tested negative. Results: Of the 86 patients with systemic inflammation, 29 had blood cultures positive for microbes. Of these, 18 received a specific antibiotic therapy based on their positive nose/throat cultures prior to the return of the blood cultures from the laboratory. However, only 11 patients tested positive for the same microbes on routine swabs and blood cultures. While positive routine swabs are quite specific to sepsis when there is a systemic inflammatory response, routine swabs are not a suitable screening tool due to their low sensitivity. Conclusion: Routine nose/throat swabs led to earlier specific antibiotic treatment in only 22% of patients with clinical signs of systemic inflammation. In 36% of cases, the organisms detected in the routine swabs and blood cultures were not identical. Hence, we believe that routine swabs are of limited value in instituting earlier, specific antibiotic therapy in septic patients.

Babesiosis and HIV

9/L). We found no morulae on microscopic examination of a Wright-stained peripheral blood smear, but suspected that he had human granulocytic anaplasmosis, and started oral doxycycline 100 mg twice daily. Serological testing for antibodies to Anaplasma phagocytophilum was later reported to be positive (>1:80). Routine blood cultures were negative. The patient returned in 1 week without clinical improvement and a platelet count of 1810 9 /L and haemoglobin of 100 mg/L. We repeated the blood smear, and stained it with Giemsa this time, and found plentiful babesia merozoites (figure, top). We started oral clindamycin and quinine.

Application of an rRNA probe matrix for rapid identification of bacteria and fungi from routine blood cultures.

One of the most important functions of the clinical microbiology laboratory is the identification of the etiology of sepsis. For this study, aliquots from 405 positive blood cultures were tested against a unique array of DNA probes directed against rRNA subsequences of bacteria and fungi for identification. Another 280 samples that were negative after 5 days of incubation were also tested. Blood culture bottles were incubated in a BacT/Alert3D instrument. For the rRNA assay, a 0.4-ml aliquot was removed, and the cells were pelleted by centrifugation. The pellet was washed and frozen at -70 degrees C. Analysis of the pellet involved a lysis step and then the addition of samples to the reaction wells containing the probes in a microtiter plate format. Analysis was performed by using a hybridization protection assay. Results were taken through a series of deductive steps to obtain species, or in some cases genus, identification. Batch sample preparation required approximately 15 min, and sample analysis required another 60 min. Probe results were compared to conventional biochemical identifications. The probe test was negative for the 280 samples that were negative by the BacT/Alert 3D system and for another 21 samples that were false positive (the instrument signaled, but there was no growth). Microorganisms from the remaining 384 signal-positive samples included 60 Enterobacteriaceae, 10 Pseudomonas aeruginosa, 10 other gram-negative bacteria, 40 Staphylococcus aureus, 152 coagulase-negative staphylococci, 28 streptococci, 22 enterococci, 21 other gram-positive bacteria, 8 anaerobes, and 16 yeast organisms. Seventeen cultures were polymicrobial, and one was gram positive and culture negative. Discordance between probe and conventional identification results was noted for only 12 (1.75%) samples. This novel rapid molecular approach to the identification of bacteria and yeast in blood cultures was highly sensitive (100%) and specific (96%).

Pregnancy in an Intravenous Drug User - Problem of Obstetric Management.

Mycobacterium chelonae, a species of rapidly growing mycobacteria, may grow in routine blood culture media and stain as gram-positive bacilli, which may cause diagnostic confusion. A patient with native-valve endocarditis caused by M. chelonae, which was misidentified as various gram-positive bacilli, is presented.

Direct identification of Staphylococcus aureus from positive blood culture bottles.

Fluorescence in situ hybridization (FISH) using peptide nucleic acid (PNA) probes targeting Staphylococcus aureus 16S rRNA is a novel method for direct identification of S. aureus from positive blood culture bottles. The test (S. aureus PNA FISH) is performed on smears made directly from positive blood culture bottles with gram-positive cocci in clusters (GPCC) and provides results within 2.5 h. A blinded comparison of S. aureus PNA FISH with standard identification methods was performed in collaboration with eight clinical microbiology laboratories. A total of 564 routine blood culture bottles positive for GPCC recovered from both aerobic and anaerobic media from three different manufacturers (ESP, BACTEC, and BacT/Alert) were included in the study. The sensitivity and specificity of S. aureus PNA FISH were 100% (57 of 57) and 99.2% (116 of 117), respectively, with 174 GPCC-positive ESP blood culture bottles, 98.5% (67 of 68) and 98.5% (129 of 131), respectively, with 200 GPCC-positive BACTEC blood culture bottles, and 100% (74 of 74) and 99.1% (115 of 116), respectively, with 190 GPCC-positive BacT/Alert blood culture bottles. It is concluded that S. aureus PNA FISH performs well with commonly used continuously monitoring blood culture systems.

Emergence of ganciclovir-resistant cytomegalovirus in lung transplant recipients

Background Since ganciclovir-resistant cytomegalovirus (CMV) disease was initially described in a patient with acquired immunodeficiency syndrome (AIDS) in 1986, the incidence of ganciclovir-resistant CMV disease appears to be increasing in immunocompromised patients. More recently, there have been sporadic reports of ganciclovir-resistant CMV disease in solid organ transplantation. Methods We retrospectively assessed the incidence of ganciclovir-resistant CMV disease in all lung transplant recipients transplanted between 6/93 and 6/01 at Loyola University Medical Center. All patients underwent routine CMV blood culture, shell vial assay as well as phenotypic and genotypic anti-viral susceptibility testing according to a pre-determined schedule. The number of CMV episodes, intravenous ganciclovir use, acute and chronic rejection and survival data were documented for all patients. Results Twelve of 212 (6%) transplant recipients developed ganciclovir-resistant CMV disease. Ganciclovir resistance was associated with a higher number of CMV episodes (3.4 ± 2.3 episodes/patient vs 1.7 ± 0.7 episodes/patient [ p < 0.05]) and an increased exposure to cumulative intravenous ganciclovir in the primary CMV-mismatched (D +R −) population (22 ± 10 vs 13 ± 7 days [ p < 0.05]) compared with patients who did not develop ganciclovir resistance. In addition, the use of daclizumab therapy was associated with a 7-fold greater likelihood of developing ganciclovir resistance ( p < 0.0001). The presence of ganciclovir-resistant CMV disease in our population was associated with a decreased survival that could be attributed to CMV disease itself ( p < 0.05). Conclusions By screening all lung transplant recipients with CMV disease for ganciclovir resistance, we were able to detect a higher incidence of ganciclovir-resistant CMV disease (6%) than previously seen in solid organ transplantation. High-risk patients (D +R − CMV serostatus) who receive anti-lymphocytic therapy should be monitored aggressively and treated to prevent the development of ganciclovir resistance and avert a negative outcome.

Utility of Anaerobic Blood Cultures for the Isolation of Nonanaerobic Organisms

It has been postulated that a major benefit of routine anaerobic blood culturing is actually the identification of nonanaerobic (microaerophilic or facultative anaerobe) organisms. In a retrospective analysis of four hospitals for a consecutive 6-month period, an infectious disease specialist reviewed the charts for cases in which nonanaerobes grew only in anaerobic bottles. Analysis included determining whether the same bacteria were found in other cultures (and how often); whether treatment was initiated; and whether anaerobic growth changed or improved management. Forty-eight (0.32%) of 14,760 sets of blood cultures yielded microaerophilic organisms only in anaerobic bottles. Thirty-four (71%) of these 48 cases were deemed isolations of “contaminants” after chart review; 14 (29%) were considered isolations of true pathogens. Ten isolates (seven contaminants and three pathogens) were identified from at least two different anaerobic culture bottles (i.e., different blood culture specimens). Two contaminants and three pathogens were also isolated from non-blood-culture specimens. Only 11 true pathogens (.07%) from 14,760 blood cultures grew solely in a single anaerobic bottle culture bottle and were not isolated from any other site. Our study did not demonstrate any benefit of performing routine anaerobic blood cultures for the identification of microaerophilic organisms. Only 14 (0.09%) of 14,760 anaerobic cultures yielded a true microaerophilic pathogen, of which 5 isolates were identified through other cultures or tests.

Organophosphate-based pesticides and genetic damage implicated in bladder cancer

Organophosphate-based pesticides have been associated with pathology and chromosomal damage in humans. There are also epidemiologic links with cancer. The few screening tests for low-level occupational exposure are of doubtful sensitivity; this investigation evaluated four methods. Blood samples were studied from 10 farmers before and after occupational exposure to organophosphate-based pesticides and five unexposed controls. The standard cholinesterase test was insensitive to the exposure ( P=0.815). However, a significant increase in Howell-Jolly bodies within erythrocytes was observed ( P=0.001). Cytogenetic studies on routine and aphidicolin-induced blood cultures revealed that following organophosphate exposure the total number of gaps and breaks on human chromosomes was significantly increased ( P=0.004 and P=0.0006, respectively). We concluded that Howell-Jolly body and fragile site analysis were sensitive indicators of nuclear damage resulting from low-level occupational exposure to organophosphate. Such nuclear damage could be implicated in carcinogenesis. The development of bladder cancer is one such example.