G. Marklein

Utility of a Commercially Available Multiplex Real-Time PCR Assay To Detect Bacterial and Fungal Pathogens in Febrile Neutropenia

ABSTRACT Infection is the main treatment-related cause of mortality in cancer patients. Rapid and accurate diagnosis to facilitate specific therapy of febrile neutropenia is therefore urgently warranted. Here, we evaluated a commercial PCR-based kit to detect the DNA of 20 different pathogens (SeptiFast) in the setting of febrile neutropenia after chemotherapy. Seven hundred eighty-four serum samples of 119 febrile neutropenic episodes (FNEs) in 70 patients with hematological malignancies were analyzed and compared with clinical, microbiological, and biochemical findings. In the antibiotic-naïve setting, bacteremia was diagnosed in 34 FNEs and 11 of them yielded the same result in the PCR. Seventy-three FNEs were negative in both systems, leading to an overall agreement in 84 of 119 FNEs (71%). During antibiotic therapy, positivity in blood culture occurred only in 3% of cases, but the PCR yielded a positive result in 15% of cases. In six cases the PCR during antibiotic treatment detected a new pathogen repetitively; this was accompanied by a significant rise in procalcitonin levels, suggestive of a true detection of infection. All patients with probable invasive fungal infection (IFI; n = 3) according to the standards of the European Organization for Research and Treatment of Cancer had a positive PCR result for Aspergillus fumigatus; in contrast there was only one positive result for Aspergillus fumigatus in an episode without signs and symptoms of IFI. Our results demonstrate that the SeptiFast kit cannot replace blood cultures in the diagnostic workup of FNEs. However, it might be helpful in situations where blood cultures remain negative (e.g., during antimicrobial therapy or in IFI).

Clostridium difficile infection in patients with neutropenia.

Clostridium difficile is the most important cause of nosocomial infectious diarrhea. The importance of C. difficile-associated diarrhea (CDAD) has been poorly investigated in patients with neutropenia who have hematologic malignancies. A retrospective chart review of all patients treated in the leukemia ward of a university medical center during 1991-2000 determined that 875 courses of myelosuppressive chemotherapy were administered. CDAD occurred in 7.0% of all cycles. In 8.2% of the patients, severe enterocolitis developed. Two patients died while they had diarrhea. However, in no patient was C. difficile infection clinically considered to be the primary cause of death. The response rate to oral metronidazole was 90.9%. These data indicate that C. difficile infection is not rare and should be suspected whenever a hospitalized patient with neutropenia develops diarrhea. Oral metronidazole can be recommended as initial drug of choice for treatment of patients with neutropenia who have hematologic malignancies and CDAD.

Breakthrough invasive fungal infections in neutropenic patients after prophylaxis with itraconazole

This study analyses invasive fungal infections in neutropenic patients with haematological malignancies during antifungal prophylaxis with itraconazole. From September 1994 to December 1998 20 patients developed fungal infections. Two patients suffered from disseminated infections by yeasts and 18 patients suffered from pulmonary infections by moulds (eight proven, 10 highly probable in high‐resolution CT scans). In these patients the itraconazole trough concentrations exceeded 500 ng ml−1 (measured by high performance liquid chromatography) significantly less often (median 48%, interquartile range 0–100%) than in another group of 150 leukaemia patients without invasive fungal infections who received 287 courses of prophylaxis with itraconazole at our institution (median 100%, interquartile range 38–100%, P=0.039). Twelve patients died, six of these had refractory disease. Patients with fatal invasive fungal infections had lower median itraconazole concentrations immediately before occurrence of the infection than patients with non‐fatal infections: 120 (0–478) ng ml−1 versus 690 (305–1908) ng ml−1 (P=0.039). In conclusion, this analysis of breakthrough invasive fungal infections during prophylaxis with itraconazole demonstrates that patients with itraconazole trough concentrations below 500 ng ml−1 were significantly more likely to develop fungal infections and that the last itraconazole trough concentration before occurrence of the infection was significantly lower in patients with fatal invasive fungal infections.

Itraconazole trough concentrations in antifungal prophylaxis with six different dosing regimens using hydroxypropyl-β-cyclodextrin oral solution or coated-pellet capsules

We have previously shown that a trough concentration of at least 500 ng ml−1 itraconazole is necessary for an effective antifungal prophylaxis in neutropenic patients. Since the bioavailability of itraconazole is reduced in these patients, a satisfactory dosing regimen remains to be defined. In this study, six dosing regimens with itraconazole capsules 400, 600 or 800 mg day−1, itraconazole solution 400 mg day−1 (additional loading dose: 400 mg day−1 solution for 2 days), 800 mg day−1 or 400 mg day−1 (additional loading dose: 800 mg day−1 capsules for 7 days, s/c1200) were compared during 160 courses of myelosuppressive chemotherapy in 123 patients with acute leukaemia. After the first week, patients taking 800 mg day−1 or 400 mg day−1 (s/c1200) itraconazole solution achieved significantly higher trough concentrations (high‐performance liquid chromatography) than patients in other groups (P<0.05) and 87 and 100%, respectively, of these had concentrations >500 ng ml−1. Contrary to a dose of 400 mg day−1, a dose of 800 mg day−1 itraconazole solution induced severe nausea and vomiting in 46% of the patients. We conclude that 400 mg day−1 itraconazole solution with a loading dose of 800 mg day−1 capsules for 7 days resulted in sufficient trough concentrations from the first week onwards and appears to be suitable for antifungal prophylaxis in neutropenic patients.

Abdominal infections in patients with acute leukaemia: a prospective study applying ultrasonography and microbiology

Summary.  A prospective study of 62 chemotherapy‐ induced neutropenic episodes in patients with acute leukaemia was conducted to determine the incidence and causes of abdominal infections, and to assess the diagnostic value of the combined use of ultrasonography (US) and microbiology. Each patient underwent US of liver, gallbladder and complete bowel before chemotherapy, on days 2–4 after the end of chemotherapy and in cases of fever, diarrhoea or abdominal pain. US was combined with a standardized clinical examination and a broad spectrum of microbiological investigations. From January to August 2001, 243 US examinations were performed. The overall incidence of abdominal infectious diseases was 17·7% (11 out of 62, 95% confidence interval (CI): 9–29%). Four patients (6·5%) developed neutropenic enterocolitis; two of them died, two survived. Bowel wall thickening (BWT) > 4 mm in these four patients ranged from 5·8 to 23·6 mm and was detected only in one patient with mucositis. In three other patients (4·8%) Clostridium difficile, and in one patient (1·6%) Campylobacter jejuni, caused enterocolitis without BWT. Cholecystitis was diagnosed in three patients (4·8%) and hepatic candidiasis was strongly suspected in one patient. Abdominal infections caused by gastroenteritis viruses, cytomegalovirus (CMV) or Cryptosporidium were not observed. We conclude that in neutropenic patients with acute leukaemia receiving chemotherapy: (i) BWT is not a feature of chemotherapy‐induced mucositis and should therefore be considered as sign of infectious enterocolitis; (ii) viruses, classic bacterial enteric pathogens (Salmonella, Shigella, Yersinia, Campylobacter, Aeromonas, Vibrio subsp., enterohaemorrhagic Escherichia coli) and Cryptosporidium have a very low incidence; and (iii) abdominal infections may be underestimated when US is not used in every patient with abdominal pain.

Value of routine microbial investigation in community-acquired pneumonia treated in a tertiary care center.

The study was conducted at a tertiary care and teaching hospital with about 200 beds for internal medicine. The objective was to determine the diagnostic yield and value in directing antibiotic therapy of a routine microbial approach in patients with community-acquired pneumonia referred to a tertiary care center. We studied 93 episodes in a retrospective study. 69/93 (74%) cases were treated with at least one empirical antibiotic therapy prior to admission. Microbial investigation was performed in 83/93 cases (89%). An etiological agent was established in 19/83 (23%) cases including 7/50 (14%) by blood culture and 12/52 (23%) by serology. Bronchoscopy with 18 protected specimen brush and 20 bronchoalveolar lavage examinations was definitely diagnostic in only 1/25 (4%) cases, and this case was also identified by blood culture. 5/25 (20%) were probably diagnostic. Three pathogens, Streptococcus pneumoniae, Mycoplasma pneumoniae and Legionella pneumophila, accounted for 15/19 (79%) of the identified agents. The diagnostic results directed a change in antibiotic therapy in 6/19 (32%) of cases with definitely proven pathogens. 4/19 (21%) of cases would have been treated with an inappropriate regimen without diagnostic results. The diagnostic yield of routine microbial investigation in pretreated patients is low. The routine approach reveals its limited value especially in patients with severe courses. The role of bronchoscopy remains to be defined for patients with severe (and pretreated) community-acquired pneumonia.

Severe Abdominal Infections in Neutropenic Patients

Abdominal infections are an important cause of morbidity and mortality in neutropenic patients. We present a retrospective series of 16 patients, mostly with acute leukemia, who developed severe abdominal infections during chemotherapy-induced neutropenia between 1991 and 1997. The frequency among patients with acute leukemia was 2.35% (13 of 553). Thirteen patients presented with enterocolitis and 3 patients presented with cholecystitis. Eight patients died. Bacteremia was present in 6 patients, 4 patients suffered from proven or strongly suspected fungal infections, and 1 patient suffered from cytomegalovirus infection. Early surgical management was required in a patient with intestinal obstruction, whereas other patients could be managed conservatively. Two patients with acute cholecystitis were treated with antibiotics until the end of neutropenia and then were resected. Severe abdominal infections in neutropenic patients, which are often fatal, were caused by nonbacterial microorganisms in one-fourth of the cases and could be managed conservatively in most instances.

Selective isolation of Pseudallescheria and Scedosporium species from respiratory tract specimens of cystic fibrosis patients.

Background: Fungi of the Pseudallescheria/Scedosporium complex are known to be colonizers and infectious agents of the respiratory tract of cystic fibrosis (CF) patients. Colonized CF patients are at high risk for the development of disseminated scedosporiosis after lung transplantation. The detection of these fungi may be difficult, because they grow slowly and so will be overgrown by faster-developing microorganisms on the media routinely used in diagnostic laboratories. Objectives: To examine the usefulness of the isolation medium SceSel+ agar as a diagnostic tool for clinical samples from CF patients. Methods: 150 respiratory tract samples from 42 CF patients were inoculated on SceSel+ agar. During the incubation phase, which lasted up to 30 days at 36 ± 1°C, the cultures were inspected every 2 or 3 days. Results: The isolation of Scedosporium species was successful in 3 samples (2%) with standard microbiological media and procedures, while the isolation rate on SceSel+ agar was 5.3% (8 of 150 specimens). Conclusions: Our results suggest that standard microbiological media and procedures are not sufficient to detect colonization of the respiratory tract by Pseudallescheria/Scedosporium in CF patients. By use of SceSel+ agar, fungi belonging to this complex were isolated more frequently. Therefore, this semiselective mycological isolation medium should be used for the detection of these fungi in the respiratory tract of CF patients, especially in patients in whom a fungal infection is assumed or who are scheduled for lung transplantation.

Geotrichum capitatum septicaemia in neutropenic patients: case report and review of the literature

Summary. We report a case of systemic infection with Geotrichum capitatum in a patient with acute myeloid leukaemia. Three days before death, the patient developed acute renal failure, probably caused by occlusion of glomerula with hyphae of G. capitatum. Up until now, prophylaxis and treatment of infections caused by Geotrichum capitatum have not been established. However, the prophylactic administration of high‐dose itraconazole and the therapeutic use of liposomal amphotericin B are subjects of discussion.

False positivity of the Aspergillus galactomannan Platelia ELISA because of piperacillin/tazobactam treatment: does it represent a clinical problem?

OBJECTIVES False-positive results of the galactomannan (GM) ELISA caused by concurrent administration of piperacillin/tazobactam have been reported in patients with febrile neutropenia. PATIENTS AND METHODS This prospective study investigated different sampling times in 30 patients receiving piperacillin/tazobactam for febrile neutropenia. RESULTS Prior to the first piperacillin/tazobactam infusion, a median GM index of 0.2 [interquartile range (IQR) 0.1-0.3] was noted; in two patients (7%) the index was 0.5. Immediately after piperacillin/tazobactam infusion, the median index increased to 0.3 (IQR 0.2-0.4, P = 0.002) leading to 21% (7/30) false-positive results, if > or = 0.5 is assumed as the cut-off level. GM indices before the next piperacillin/tazobactam infusion were not increased (median 0.2, IQR 0.2-0.35, P > 0.05), but 10% (3/30) were still > or = 0.5. With a cut-off level of > 0.7, no false-positive results were noted at any sampling time point. CONCLUSIONS We conclude that the clinical relevance of false-positive GM results during piperacillin/tazobactam treatment is small if samples are collected prior to infusion and if a cut-off level of > 0.7 is used.