Bacteraemia due to Stenotrophomonas maltophilia: an analysis of 45 episodes

OBJECTIVE: Stenotrophomonas maltophilia is an important nosocomial pathogen and a therapeutic challenge. A ten-year review of episodes of bacteraemia due to S. maltophilia was undertaken in light of reports of an increasing frequency of infection. METHODS: A retrospective analysis of bloodstream infections due toS. maltophilia at a tertiary care hospital in Melbourne, Australia. Cases were identified via microbiology laboratory reports, and relevant clinical data were collected from the medical record of each patient. RESULTS: Eighty per cent of these 45 episodes were nosocomial. The most common characteristics in cases of bacteraemia were the presence of an indwelling central venous catheter (CVC) (38/45, 84%) and previous antibiotic therapy (33/45, 73%). There were 8 deaths (8/44, 18%) within 7 days of bacteraemia. A significant correlation was found between deaths and a failure to remove the CVC (P = 0.01) or treat with appropriate antimicrobials (P = 0.01). Antibiotic susceptibility testing revealed that isolates were most sensitive to sulphamethoxazole (80%), chloramphenicol (75.5%) and ceftazidime (64.5%). CONCLUSIONS: S. maltophilia is an important pathogen especially in the highly compromised host. Isolation of this organism from a blood culture should prompt a careful review of the patient with particular emphasis on removal of indwelling CVCs and commencement of appropriate antibiotic therapy.     

High-risk febrile neutropenia in Auckland 2003-2004: the influence of the microbiology laboratory on patient treatment and the use of pathogen-specific therapy

Background: International guidelines recommend routine microbiological assessment of patients with febrile neutropenia, but do not recommend a change from broad-spectrum antibiotic therapy to pathogen-specific therapy when a clinically relevant organism has been isolated. The aim of the study was to determine the aetiology of febrile neutropenia in adult haematology patients at Auckland City Hospital, to document the changes in treatment made following isolation of a clinically relevant organism and to assess adverse outcomes in any patient who received pathogen-specific therapy after a positive culture result. Methods: The results of all microbiological tests together with antibiotic therapy were recorded from consecutive patients with fever and a neutrophil count <0.5 × 10⁹/L over 1 year beginning in May 2003. Results: One thousand one hundred and ninety-six specimens were collected from 81 patients during 116 episodes of febrile neutropenia. A pathogen was isolated from blood cultures in 40 episodes: Gram-positive cocci accounted for 46% of isolates and Gram-negative bacilli for 35%. Isolation of a pathogen from blood cultures resulted in a change of treatment in 25 of 40 (62.5%, 95%CI 46–77%) episodes. In 12 of these episodes, antibiotic therapy was optimized to a single pathogen-specific agent. No adverse events or subsequent changes in antibiotic therapy occurred in any of these 12 patients. Isolation of a pathogen from specimens other than blood seldom led to a change in therapy. Conclusion: Isolation of a pathogen from blood cultures often allows antibiotic therapy to be simplified to a pathogen-specific regimen. Further study of this approach is warranted.     

Donor-derived infections among Chinese donation after cardiac death liver recipients

AIM To investigate blood cultures of deceased donors and report the confirmed transmission of bacterial infection from donors to liver recipients.METHODS We retrospectively studied the results of blood cultures among our donation after cardiac death(DCD) donors and calculated the donor-derived bacterial infection rates among liver recipients. Study participants underwent liver transplantation between January 1, 2010 and February 1, 2017. The study involved a total of 67 recipients of liver grafts from 67 DCD donors. We extracted the data of donors' and patients' characteristics, culture results and clinical outcomes, especially the post-transplant complications in liver recipients, from electronic medical records. We analyzed the characteristics of the donors and the corresponding liver recipients with emphasis put on donor-derived infections.RESULTS Head trauma was the most common origin of death among our 67 DCD donors(46.3%). Blood taken prior to the procurement operation was cultured for 53 of the donors, with 17 episodes of bloodstream infections developing from 13 donors. The predominant organism isolated from the blood of donors was Gram-positive bacteria(70.6%). Only three(4.5%) of 67 liver recipients developed confirmed donor-derived bacterial infections,with two isolates of multidrug-resistant Klebsiella pneumoniae and one isolate of multidrug-resistant Enterobacter aerogenes. The liver recipients with donorderived infections showed relation to higher crude mortality and graft loss rates(33.3% each) within 3 mo post transplantation, as compared to those without donor-derived infections(9.4% and 4.7%, respectively). All three liver recipients received appropriate antimicrobial therapy.CONCLUSION Liver recipients have high occurrence of donor-derived infections. The liver recipients with donor-derived multidrug-resistant Enterobacteriaceae infections can have good outcome if appropriate antimicrobial therapy is given.     

Antibiotic use in patients admitted with acute exacerbations of chronic obstructive pulmonary disease.

The objective of this report was to document the pattern of initial antibiotic prescribing in acute exacerbations of chronic obstructive pulmonary disease (COPD) in a hospital setting. All episodes of acute exacerbation of COPD, as diagnosed by the admitting doctor, in one hospital in the period January to May 1996, were identified. Case notes were reviewed retrospectively. Cases of radiographic pneumonia, bronchiectasis and incorrectly coded admissions were excluded. Symptoms, microbial cultures and initial antibiotic therapies were recorded. One hundred and fifty-nine patient episodes were identified; 40 were excluded yielding a sample of 119. Nineteen case notes were unavailable leaving a sample of 100 (84%) episodes. Eighty were treated with antibiotics on admission; amoxycillin was the most frequently prescribed, in 46 (58%) episodes. Of the antibiotic treated group, 42 (53%) patients were given dual therapy, most commonly a macrolide antibiotic with either amoxycillin or a cephalosporin. Intravenous treatment was used in 22 (28%) cases. The duration of intravenous treatment was >48 h in 12 (15%) cases. A total of 76 sputum samples were analysed from 55 patient episodes: 34 (45%) were culture positive. In 15 (27%) patient episodes, antibiotic therapy was changed or instituted on the basis of culture results. These data suggest that antibiotic treatment is not optimal, with overuse of antibiotics, especially intravenous and dual therapy.     

Blood stream infections throught the entire course of acute lymphoblastic leukemia treatment

The incidence, type and mortality of bacteremias were evaluated in a pediatric patient cohort, during the entire course of treatment for acute lymphoblastic leukemia (ALL). Eighty-six patients with newly diagnosed ALL were studied. A bacteremic episode was defined as blood isolation of a pathogen in the presence of clinical symptomatology of septicaemia. Bacteremias were analyzed according to the treatment element being delivered and the degree of neutropenia. A central venous catheter (CVC) was inserted at diagnosis in all patients. Fifty-two episodes of bacteremias were encountered in 38/86 (44%) patients, while 48/86 patients had no positive blood culture. Three out of the 38 patients had bacteremia and CVC area infection, simultaneously. Most blood stream infections (29/52, 56%) were documented during the induction phase. Isolated Gram-positive organisms were 48%, Gram-negative 50% and 2% of the positive blood cultures represented fungaemias. The most common Gram-positive isolates were Staphylococcus species (N=22) and the commonest Gram-negative isolated pathogens were Escherichia coli and Pseudomonas aeruginosa. The majority of bacteremias (75%) occurred during neutropenia. The initial antibiotic treatment was ceftazidime or piperacillin/tazobactam and amikacin or tobramycin. CVC was not removed in the majority of bacteremias (94%). No infection related fatality was recorded. Bacteremias constituted a severe and common complication in our patient cohort. However, infection-related fatality rate was negligible, most probably due to the prompt initiation of broad coverage antimicrobial therapy.     

Combination of Amikacin and either Ampicillin or Cephalotin as Initial Treatment of Febrile Neutropenic Patients

ABSTRACT. A prospective, randomized trial of two antibiotic combinations (amikacin plus either ampicillin or cephalotin) was performed on 39 consecutive episodes of fever in 30 patients with neutropenia and hematological malignancy. Infections were documented as the cause of fever in 37 episodes (95%): in 21 episodes (54%) bacteria or a virus (n=1) were isolated, and in 16 (41% of all episodes) the infection was documented clinically but no pathogen was isolated. The most frequently isolated bacteria were Staph, aureus (38% of all strains), E. coli (13%), and Pseudomonas aeruginosa (13%). Bacteremia occurred in 18% of the febrile episodes. Improvement followed treatment with the combination amikacin plus ampicllin in 73% of 19 cases, and with amikacin plus cephalotin in 55% of 20 cases (p>0.05), giving a total Improvement rate of 64%. Failure of therapy was seen in episodes caused by multiple bacteria or Pseudomonas infections. Mild signs of nephrotoxicity were noted in 13% during both regimens. Audiograms were normal in all but two patients who showed slight high-frequency hearing loss. A second infection occurred in 7 episodes (18%). Thus, the combination of amikacin plus ampidllin was as efficient (but less expensive) as amikacin plus cephalotin in the initial treatment of febrile episodes in neutropenic patients with hematological malignancies.     

Positive urine cultures: A major cause of inappropriate antimicrobial use in hospitals?

INTRODUCTION

Urine specimens are among the most common samples submitted for culture to microbiology laboratories. The objectives of the present study were to describe the indications for obtaining urine cultures in a cohort of hospitalized patients, and to determine the appropriateness of antimicrobial therapy in response to urine culture results.

METHODS:

The study was performed at a teaching hospital with an adjoining long-term care facility from June 1 to July 31, 2006. The medical records of nonpregnant adult patients with and without bacteriuria were reviewed. A symptomatic urinary tract infection was defined as the presence of bacteriuria in a patient with fever or urinary symptoms; asymptomatic bacteriuria was defined as bacteriuria without urinary symptoms and no infection evident at another site.

RESULTS:

Medical records of 335 eligible patients (64% male; mean age 68 years) were reviewed, including all 137 with bacteriuria, and 198 with negative urine cultures. In total, 51% of the urine specimens were obtained from an indwelling urinary catheter, and 28% were voided urine samples. Confusion (57%) and fever (36%) were the most common indications noted for obtaining the urine cultures. Only 34 patients (25% of those with positive urine cultures) met the criteria for a symptomatic urinary tract infection; 67 (49%) had asymptomatic bacteriuria and 36 (26%) had infection at a nonurinary site. Of those with asymptomatic bacteriuria, 64% received antimicrobial therapy for a total of 347 days. Confused patients with asymptomatic bacteriuria were more likely to be treated than were bacteriuric patients without altered mental status (OR 1.8, 95% CI 1.2 to 4.1; P=0.03).

CONCLUSIONS:

Urine cultures are frequently obtained from hospitalizedpatients,evenintheabsenceofurinarysymptoms.Asymptomatic bacteriuria is often treated in these patients, and accounts for a substantial burden of inappropriate antimicrobial use in hospitals. Effective strategies to improve urine culture ordering and antimicrobial utilization in hospitals need to be implemented.     

Therapeutic antibiotic monitoring: surveillance using a computerized expert system

STUDY OBJECTIVE: To develop and evaluate a computerized system to monitor therapeutic antibiotics in a hospital setting. MATERIAL AND METHODS: From November 1986 through October 1987, we prospectively monitored 1,632 hospitalized patients who had 2,157 microbiology specimens sent for culture and sensitivity testing. During the study period, computer algorithms were used to identify patients whose antibiotic therapy was inappropriate in relation to microbiology culture and sensitivity data. When inconsistencies occurred between antibiotic therapy and in vitro sensitivity data, computer algorithms generated therapeutic antibiotic monitor (TAM) alerts. A clinical pharmacist then notified the attending physician of the alert. RESULTS: Antibiotic therapy was identified by the computer as inappropriate in 696 instances (32%). After we eliminated false-positive alerts, 420 evaluable TAM alerts remained. Physicians responded to the TAM alerts by either changing or starting antimicrobial therapy in 125 cases (30%). Moreover, physicians were previously unaware of the relevant susceptibility test results in 49% of the alerts. CONCLUSION: Computer-assisted monitoring is an efficient and promising method to identify and correct errors in antimicrobial prescribing and to assure the appropriate use of therapeutic antibiotics.     

Inappropriate urine cultures in hospitalized patients receiving antibiotic therapy

To investigate the effect of concurrent antibiotic therapy on bacterial isolation, 1001 consecutive urine cultures obtained from hospitalized patients were evaluated. Of the cultures, 121 (12.1%) had positive results. The administration of antibiotic therapy substantially changed urine culture results in uncatheterized patients. Only one (0.7%) of 135 cultures obtained from patients without a recent history of catheterization was positive when antibiotics were being administered. In contrast, 43 (8.6%) of 501 urine cultures obtained from uncatheterized patients not receiving antibiotic therapy were positive. These results indicate that concurrent antibiotic therapy should be considered before ordering urine cultures in uncatheterized patients. Substantial savings would result if, in this situation, cultures were limited to patients with urinary tract symptoms or a history of urinary tract pathology.     

Role of serial routine microbiologic culture results in the initial management of ventilator-associated pneumonia.

Results of routine microbiologic cultures of specimens obtained before the onset of ventilator-associated pneumonia (VAP) in intensive care unit (ICU) patients might help to identify the causative microorganisms and thus to select effective initial antimicrobial therapy. To test this hypothesis, we prospectively studied 125 consecutive VAP episodes for which the causative microorganisms were determined using bronchoscopic techniques. Upon entry into the study, each patient's hospital chart was reviewed and culture results of all previously obtained microbiologic specimens were recorded (mean number +/- SD per patient, 45 +/- 38). A total of 220 microorganisms were cultured at significant concentrations (> or = 10(3)/10(4) colony-forming units [cfu]/ml) from bronchoscopic specimens and considered responsible for pneumonia. Of these 220 organisms, only 73 (33%) were recovered before VAP onset, sometimes from multiple sites in the same patient but mainly from prior respiratory secretion cultures (n = 53). Also previously isolated were 342 organisms that were not responsible for VAP, making prospective identifications of the true pathogens difficult. Among the 102 episodes for which prior respiratory secretion culture results had been obtained (mean time before VAP onset, 8 +/- 9 d), all the organisms ultimately responsible for pneumonia were previously recovered from only 36 (35%) of these specimens. Based on these data, the contribution of routine microbiologic specimens in guiding initial antimicrobial therapy decisions for patients with suspected VAP appears limited.     

Improved prognosis for granulocytopenic patients with gram-negative bacteremia

The grave prognosis associated with gram-negative bacteremia occurring in granulocytopenic patients with cancer suggests that granulocyte transfusions are frequently indicated. We have evaluated 67 episodes of gram-negative bacteremia, studied in four consecutive antibiotic trials, in order to correlate prognostic determinants of recovery. These patients had a median absolute granulocyte count of 100/μl at the time of bacteremia. Empiric antibiotic regimens were begun at the first evidence of suspected infection. Granulocyte transfusions were employed only as clinically indicated by inadequate patient response to antibiotic therapy. Among the 29 patients who had an increase in their granulocyte count of ?100/μl over the subsequent 14 days, 27 (93 per cent) recovered whereas among 38 patients who had no appreciable increase in their granulocyte count, 21 (55 per cent) improved (p = 0.006). In this latter group of patients with no granulocyte recovery, the susceptibility of the pathogen(s) to the initial empiric antibiotic regimen was of major importance. None of four patients responded when the pathogen was resistant to both antibiotics initially utilized, six of 14 (44 per cent) patients responded when there was susceptibility to one antibiotic, and 15 of 20 (75 per cent) patients responded when there was susceptibility to both antibiotics (p < 0.025). We conclude that patients with gramnegative bacteremia and persistent granulocytopenia will often respond to antimicrobial therapy alone provided the initial choice of empiric antibiotics is appropriate and that their use is instituted promptly. Granulocyte transfusions need not be added unless clinical evaluation indicates inadequate response.     

Pneumonia in elderly patients with preexisting respiratory disease

To evaluate the optimal duration of appropriate antibiotic therapy for pneumonia in elderly patients with preexisting respiratory disease, we studied improvement of infectious parameters in these patients. The medical record database was used to identify patients admitted with the following characteristics: primary diagnosis of benign respiratory disease; aged 65 years or over; no active malignant diseases in any organs; and at least one admission for pneumonia during April 2001 to May 2003. We observed 47 pneumonia episodes in 30 patients. Elevated CRP levels more than 8.0 mg/ml and leukocytosis more than 10.0 x 10(3) mm(-3) was seen in 21 and 29 pneumonia episodes, respectively. With appropriate intravenous antimicrobial therapy, average of CRP levels on day 0 (9.16 +/- 6.81 mg/dl) decreased to 5.18 +/- 4.67 mg/dl on day 3 (P = 0.0073). In more than 70% of pneumonia episodes, serum levels of CRP normalized on day 10. Average of leukocyte counts on day 0 ((12.3 +/- 4.7) x 10(3) mm(-3)) decreased to (8.1 +/- 3.5) x 10(3) mm(-3) on day 3 (P = 0.0001). In more than 80% of pneumonia episodes, leukocyte count normalized on day 7. The clinical response to appropriate antimicrobial therapy for pneumonia occurs within the first 3 days of therapy. Duration of intravenous antimicrobial therapy for pneumonia in these patients of 10 days would be sufficient and could prevent recurrent infection with resistant bacteria.     

Health care-associated pneumonia (HCAP): empiric antibiotics targeting methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa predict optimal outcome

Inappropriate initial antimicrobial therapy (IIAT) has been associated with decreased survival in patients with health care-associated pneumonia (HCAP). We performed a study to determine whether empiric HCAP antibiotic regimens targeting methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa are associated with greater appropriate therapy. A retrospective cohort study of culture-positive HCAP over 6 years (January 2003-December 2008) was performed at Barnes-Jewish Hospital, a 1200-bed urban teaching hospital. We identified 757 consecutive patients with HCAP. IIAT was administered to 213 (28%) patients. The pathogens most frequently associated with IIAT included P. aeruginosa (n=60, 28%), MRSA (n=58, 27%), and Acinetobacter species (n=32, 15%).Multivariate logistic regression analysis demonstrated that empiric anti-pseudomonal antibiotics (adjusted odds ratio [AOR], 1.75; 95% confidence interval [CI], 1.34-2.29; p=0.036), empiric anti-MRSA antibiotics (AOR, 1.71; 95% CI, 1.36-2.14; p=0.018), infection with Streptococcus pneumoniae (AOR, 2.82; 95% CI, 2.03-3.91; p=0.002), absence of Acinetobacter species infection (AOR, 10.57; 95% CI, 7.29-15.33; p<0.001), absence of P. aeruginosa infection (AOR, 1.69; 95% CI, 1.36-2.05; p=0.014), and absence of Stenotrophomonas maltophilia infection (AOR, 20.43; 95% CI, 9.35-44.66; p<0.001) are independent predictors of appropriate therapy for HCAP. Our study suggests that initial therapy for HCAP should include antibiotics targeting MRSA and P. aeruginosa in order to provide appropriate initial therapy. However, the selection of individual antibiotic agents should be based on local patterns of infection and adjusted when microbiology results become available.     

An investigation of enterococcal bacteremia

Records of all 34 patients with positive blood cultures for enterococcus at Mount Sinai Medical Center of Greater Miami in 1981 were reviewed. Twenty-four true bacteremias were identified from sources including the pelvis/abdomen (9), urinary tract (6), wounds (2), IV catheter (2), contaminated needle (1), endocarditis (1), and primary bacteremia (3). Sixteen of the 24 true bacteremias were hospital acquired, and these infectious accounted for 7 of 9 (78%) fatal outcomes. Fourteen of 16 patients with hospital-acquired infection received prior antibiotic therapy. Eight (24%) of the original 34 patients had positive blood cultures for enterococcus as a result of cross-contamination from an automated blood culture analyzer. The rate of cross-contamination per positive blood culture for enterococcus in 1981 was 22%. Two remaining patients in the original series could not be placed in a category of true infection of cross-contamination. Although there was a real increase in the number of enterococcal bacteremias in 1981, a much larger apparent increase was explained by several episodes of pseudobacteremia.     

Evaluation of optimal treatment for urinary tract infections in outpatient clinics at an academic medical center: Opportunities for antimicrobial stewardship

Outpatient empiric urinary tract infection (UTI) prescribing is an area of interest for antimicrobial stewardship efforts. We conducted a retrospective chart review evaluating optimal antibiotic prescribing for UTIs in our internal medicine and urology clinics and found significant differences in prescribing patterns between provider type and UTI category. These data will inform our antimicrobial stewardship efforts in these clinics.     

Impact of Delayed Appropriate Antibiotic Therapy on Patient Outcomes by Antibiotic Resistance Status From Serious Gram-negative Bacterial Infections

Background

To examine the clinical and economic burdens associated with delayed receipt of appropriate therapy among patients with Gram-negative bacteria (GNB) infections, stratified by antibiotic resistance status.

Blood cultures have limited value in predicting severity of illness and as a diagnostic tool in ventilator-associated pneumonia.

STUDY OBJECTIVES: To define the usefulness of blood cultures for confirming the pathogenic microorganism and severity of illness in patients with ventilator-associated pneumonia (VAP). DESIGN: Prospective observational study using BAL and blood cultures collected within 24 h of establishing a clinical diagnosis of VAP. SETTING: A 15-bed medical and surgical ICU. PATIENTS: One hundred and sixty-two patients receiving mechanical ventilation hospitalized for > 72 h who had new or progressive lung infiltrate plus at least two of three clinical criteria for VAP. INTERVENTIONS: BAL and blood culture performed within 24 h of establishing a clinical diagnosis of VAP. MEASUREMENTS AND RESULTS: Ninety patients were BAL positive (BAL+), satisfying a microbiological definition of VAP (>/= 10(4) cfu/mL), 72 patients were BAL negative (BAL-). Bacteremia was diagnosed when at least two sets of blood cultures yielded a microorganism or when only one set was positive, but the same bacteria was present at a concentration >/= 10(4) cfu/mL in the BAL fluid. Bacteremia was significantly more frequent in the BAL+ than in the BAL- group (22/90 patients vs 5/72 patients; p = 0.006). In 6 of 22 BAL+ patients with bacteremia, an extrapulmonary site of infection was the source of bacteremia. Sensitivity of blood culture for disclosing the pathogenic microorganism in BAL+ patients was 26%, and the positive predictive value to detect the pathogen was 73%. Factors associated with mortality were age > 50 years, simplified acute physiology score > 14, prior inadequate antibiotic therapy, PaO(2)/fraction of inspired oxygen < 205, and use of H(2) blockers. By multivariate analysis, only the use of prior inadequate antimicrobial therapy (odds ratio [OR], 6.47) and age > 50 years (OR, 5.12) were independently associated with higher mortality. The rate of complications was not different in patients with bacteremia. CONCLUSIONS: Blood cultures have a low sensitivity for detecting the same pathogenic microorganism as BAL culture in patients with VAP. The presence of bacteremia does not predict complications, it is not related to the length of stay, and it does not identify patients with more severe illness. Inadequacy of prior antimicrobial therapy and age > 50 years were the only factors associated with mortality in a multivariate analysis. Blood cultures in patients with VAP are clearly useful if there is suspicion of another probable infectious condition, but the isolation of a microorganism in the blood does not confirm that microorganism as the pathogen causing VAP.     

Bacteriology of infected cavitating lung tumor

Differentiation between in situ infection and simple tumor necrosis in cavitating lung tumors by means of imaging studies is difficult. In this study, we prospectively investigated the role of ultrasound (US)-guided transthoracic aspiration for bacteriologic examination of infected cavitating lung tumors, and the influence of the culture results on the treatment of patients. Twenty-two patients (18 men and four women) with cavitating lung tumors treated from January 1996 to October 1998 were included. All patients underwent US-guided transthoracic aspiration for bacterial, fungal, and mycobacterial cultures. Microorganisms were isolated from six of seven febrile patients and one of 15 nonfebrile patients. A total of nine pathogens were isolated from seven patients: Klebsiella pneumoniae (n = 3); Haemophilus influenzae (n = 2); Enterococcus faecium (n = 1); Bifidobacterium (n = 1); Shewanella putrefaciens (n = 1); and Mycobacterium tuberculosis (n = 1). Two pathogens were isolated from the aspirate cultures in two patients, while the others had monomicrobial infection. The six febrile patients who had positive lung aspirate cultures were treated with empiric antimicrobial agents before the culture results were available, and the culture results led to adjustment of the antibiotic regimen in five of these. The clinical conditions of the six patients with infected cavitating lung tumors improved after the initiation of individualized antimicrobial treatment. Pneumothorax occurred in one patient, and was the sole procedure-related complication. In conclusion, US-guided transthoracic aspiration is helpful for differentiating infected cavitating lung tumors from simple tumor necrosis. Infection in cavitating lung tumors is common among febrile patients, and the culture results can guide modification of the antimicrobial therapy.