Electronic ventilator temperature sensors as a potential source of respiratory tract colonization with Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia (S. maltophilia) is an important cause of nosocomial infection among ventilated and immunocompromised patients, and among patients receiving broad-spectrum antimicrobials. We report a cluster of patients in a surgical intensive care unit who were colonized or infected with S. maltophilia. An epidemiological investigation was initiated after surveillance data revealed that eight patients were culture-positive from sputum for S. maltophilia in the preceding month. Review of respiratory care procedures revealed that when mechanical ventilators were serviced between patients, the electronic temperature probes used with servo-controlled humidifiers were wiped with inadequate disinfection. We collected cultures of case-patient room surfaces, sinks and ventilator equipment. S. maltophilia was recovered from room surfaces, ventilator expiratory circuits and a temperature sensor which had been kept in ambient air after disinfection. Patients and environmental isolates were examined by RAPD-PCR. Three clinical isolates and one environmental isolate had the same profile, which suggests cross-contamination or common source exposure. The outbreak was controlled by adequate disinfection of the temperature sensors. No single epidemic strain was identified but several observations support the conclusion that the temperature probes contributed to the outbreak.

Rotation and restricted use of antibiotics in a medical intensive care unit. Impact on the incidence of ventilator-associated pneumonia caused by antibiotic-resistant gram-negative bacteria.

To test the hypothesis that a new program of antibiotic strategy control can minimize the incidence of ventilator-associated pneumonia (VAP) caused by potentially antibiotic-resistant microorganisms, we performed a prospective before-after study in 3, 455 patients admitted to a single intensive care unit over a 4-yr period. Regarding the bacterial ecology and the increasing antimicrobial resistance in our medical intensive care unit (MICU), we decided to vary our choice of empiric and therapeutic antibiotic treatment, with a supervised rotation, and a restricted use of ceftazidime and ciprofloxacin, which were widely prescribed before this scheduled change. For all patients, VAP was diagnosed based on the results of quantitative culture of bronchoalveolar lavage specimens (>/= 10(4) cfu/ml). We studied 1,044 and 1,022 patients requiring more than 48 h of mechanical ventilation (MV), respectively, in the before-period (2 yr: 1995-1996) and the after-period (2 yr: 1997-1998). We observed a decrease from 231 consecutive episodes of VAP in the before-period to 161 episodes of VAP in the after-period (p < 0.01), particularly for VAP occurring before 7 d of MV. The total number of potentially antibiotic-resistant gram-negative bacilli responsible for VAP such as Pseudomonas aeruginosa, Burkholderia cepacia, Steno-trophomonas maltophilia, and Acinetobacter baumanii decreased from 140 to 79 isolated bacilli. The susceptibilities of these bacteria to the antibiotics regimen increased significantly, especially for P. aeruginosa and B. cepacia. The percentage of methicillin-sensitive Staphylococcus aureus increased significantly from 40% to 60% of S. aureus responsible for VAP. These results suggest that a new strategy of antibiotics use could be an efficient means to reduce the incidence of VAP caused by antibiotic-resistant bacteria. Nevertheless, further studies are needed to validate these data.

Utility of fiberoptic bronchoscopy in neutropenic patients admitted to the intensive care unit with pulmonary infiltrates.

OBJECTIVE: To analyze the impact of fiberoptic bronchoscopy and bronchoalveolar lavage (BAL) on guiding the treatment and intensive care unit (ICU) clinical outcome in neutropenic patients with pulmonary infiltrates admitted to the ICU. DESIGN: Prospective collection of data. SETTING: Medical ICU in a teaching hospital. PATIENTS: During a 6-yr period, we analyzed the results of 93 fiberoptic bronchoscopies plus BALs performed in 93 consecutive neutropenic ICU patients. We separated the patients into two groups according to the cause of neutropenia (high-dose chemotherapy [n = 41] or stem cell transplantation [SCT; n = 52]). RESULTS: Of the 93 BALs, 53 were performed to evaluate diffuse infiltrates and 42 were performed on mechanically ventilated patients. Forty-nine percent of BALs (46 patients) were diagnostic, with a significantly better yield in ICU patients with high-dose chemotherapy-induced neutropenia (26 of 41 BALs). The number of cases of proven infectious pneumonia was significantly higher in this group of ICU neutropenic patients. In patients who underwent SCT, diffuse infiltrates were statistically correlated with a negative result of BAL. Twenty-six patients who underwent diagnostic BALs changed therapy. Sixteen complications (17%) occurred with only two intubations. The overall mortality rate in the ICU and the mortality rate in mechanically ventilated neutropenic patients were 71% and 93%, respectively. In neutropenic patients who underwent SCT, the mortality rate was statistically higher in patients in whom no diagnosis was established. Patients who had a diagnostic BAL that changed therapy did not have an increased probability of survival compared with patients who had a BAL that did not change therapy. CONCLUSIONS: The use of routine diagnostic BAL in ICU neutropenic patients with pulmonary infiltrates is difficult to establish, even if BAL is helpful in the management of these critically ill patients. BAL in our ICU neutropenic patient population had an acceptable overall diagnostic yield (49%), which was higher in ICU patients with chemotherapy-induced neutropenia. Nevertheless, in the ICU, if BAL had a low complication rate, it had infrequently led to changed treatment and was not associated with improved patient survival.

Molecular typing of Mycoplasma pneumoniae strains by PCR-based methods and pulsed-field gel electrophoresis. Application to French and Danish isolates.

Restriction fragment length polymorphism (RFLP) analysis of the amplified P1 gene was used to type 153 strains of Mycoplasma pneumoniae isolated in France between 1977 and 1994, and in Denmark between 1962 and 1994, and an additional group of 28 strains isolated from Belgium and Germany between 1990 and 1993. Random amplified polymorphic DNA (RAPD) analysis was tested on French, Belgian and German strains. Both methods separated the strains into two groups corresponding to the two reference strains M129 (group I) and FH (group II), and gave concordant results. When 75 selected strains of different geographical origin were analysed by pulsed-field gel electrophoresis (PFGE), strains of group II fell into two closely related subgroups, subgroup IIa corresponding to the reference strain FH, and subgroup IIb. Most of the strains isolated in Denmark in the period 1962-86 belonged to group I. Almost all strains isolated in France and Denmark between 1987 and 1988 were from group II, the two subgroups being present. In 1991-3, almost all strains from France as well as Denmark, Germany and Belgium belonged to group I.

Molecular characterization of a TEM-21 beta-lactamase in a clinical isolate of Morganella morganii.

A clinical isolate of Morganella morganii, with reduced susceptibility to expanded-spectrum cephalosporins and aztreonam, was found to produce an extended-spectrum beta-lactamase with a pI of 6.4. The nucleotide sequence of the encoding gene was that of the gene encoding TEM-21. This is the first molecular characterization of an extended-spectrum beta-lactamase in M. morganii.

Early infectious complications after bone marrow transplantation requiring medical ICU admission.

The objective of this study was to define the type, the incidence and the outcome of early infectious complications (mean interval between day 1 post-BMT and the onset of fever was 9+/-3 days) occurring in granulocytopenic bone marrow transplant recipients, requiring medical intensive care unit admission. Over a five-years period, forty-one patients with microbiologically confirmed infection were enrolled, with a statistically significant higher frequency of allogeneic marrow transplant recipients (51%, p < 0.02). Infectious pneumonia occurred in 24 patients (59%), septicemia with septic shock in ten patients (24%), catheter-related infection in 5 patients (12%) and meningitis in 2 patients (5%) (p < 0.001). Twenty-six patients died (63%). Among the patients with confirmed infectious pneumonitis, which occurred most frequently in allogeneic marrow recipients (p < 0.02), 16 died (67%). This poor outcome was related to the requirement of mechanical ventilation. Eight patients (80%) with septicemia and septic shock and the two patients with meningitis died. Bacteria (Pseudomonas aeruginosa and Staphylococcal species) were the most common isolated in bronchoalveolar lavage fluid and blood cultures. We found a lower incidence of fungal or viral infections compared to previous studies. Empiric antimicrobial therapy in the cases of patients admitted in ICU may be included antibiotics anti-Pseudomonas and anti-Staphylococcus, as the ecology of hematology unit. The requirement of mechanical ventilation is the main adverse prognostic factor in transplanted patients. At ICU admission, patients with hepatic failure combined with respiratory failure represented a subgroup with a dismal prognosis.

New developments in diagnostic and treatment of mycoplasma infections in humans.

Several methods can be used for the diagnosis of mycoplasmal human infections. Culture is not satisfactory for fastidious species, while serological procedures allow only a retrospective diagnosis. Recently, rapid methods have become available. Antigenic detection proposed for Mycoplasma pneumoniae lacks sensitivity. Hybridization based techniques include DNA probes and mainly DNA amplification. The main usefulness of the polymerase chain reaction (PCR) is the detection of fastidious organisms such as M. pneumoniae, M. genitalium, M. fermentans, M. penetrans, but PCR can also be used for characterization of the strains for epidemiological purposes, or for detection of antimicrobial resistance genes. The major advantage of PCR for detection is its very high sensitivity. However, until now, the major drawback of this technique has been the lack of commercial kits. When available, they should provide better standardization of the technique and, if available at a reasonable cost, become the major technique for the diagnosis of mycoplasma infections. The antibiotics used for the treatment of mycoplasmal infections belong to tetracyclines, macrolides-lincosamides and fluoroquinolones. These products are highly active in vitro against mycoplasmas. However, some of them have a differential activity according to the species, and acquired resistance has been reported, mainly in genital mycoplasmas. Most of mycoplasmal infections are cured by adapted antibiotics, but they may be difficult to cure in immunosuppressed patients.