Mycoplasma hominis pericarditis in a lung transplant recipient: review of the literature about an uncommon but important cardiothoracic pathogen.

Purulent pericarditis due to Mycoplasma hominis is rare, and is usually associated with mediastinitis or pleuritis following cardiothoracic surgery. We report the first case to our knowledge of isolated purulent pericarditis caused by M. hominis in a lung transplant recipient and review previously reported cases of this disease.

Leuconostoc bacteremia after liver transplantation: another cause of vancomycin resistant gram-positive infection.

Leuconostoc sp. are gram-positive bacteria intrinsically resistant to vancomycin, which can be confused with streptococci based on routine microbiological-characteristics. Infections secondary to Leuconostoc are uncommon, and usually affect patients with underlying diseases, prior use of vancomycin and those with central lines. The most common clinical presentation is fever secondary to a central line infection. We report the first case of Leuconostoc infection in a solid organ transplant recipient. The patient developed Leuconostoc bacteremia secondary to peritonitis, 60 d after undergoing liver transplantation. He was treated with clindamycin, gentamicin and underwent surgical debridement, but succumbed to other complications.

Effect of quinupristin/dalfopristin on the outcome of vancomycin-resistant Enterococcus faecium bacteraemia: comparison with a control cohort.

Serious infection with vancomycin-resistant Enterococcus faecium (VREF) strains has no proven effective antimicrobial therapy. We compared the clinical and bacteriological outcomes of 20 patients with VREF bacteraemia treated with quinupristin/dalfopristin (RP 59500), an investigational streptogramin, with a historical cohort of 42 patients with VREF bacteraemia treated with other agents. Quinupristin/dalfopristin demonstrated in-vitro bacteriostatic activity against all 20 initial VREF blood isolates (MIC range 0.03-0.50 mg/L) by macrobroth dilution. The clinical characteristics of both groups were comparable for major outcome-dependent variables. There were five cases of recurrent VREF bacteraemia in the quinupristin/dalfopristin-treated cohort and 21 in the controls (P = 0.11); persistence of VREF at the primary site was found in six and 18 of the evaluable patients with follow-up cultures in these two cohorts (P = 0.06). In-hospital mortality was high in both groups: 65% in the quinupristin/dalfopristin group and 52% in the control group; however, VREF-associated mortality was significantly lower in the quinupristin/dalfopristin group (five and 17 respectively; P = 0.05). Follow-up susceptibility testing of five VREF isolates in the quinupristin/ dalfopristin group did not demonstrate resistance to quinupristin/dalfopristin. Quinupristin/ dalfopristin may be a useful agent for the therapy of serious VREF infection. Further clinical investigations are warranted to confirm or refute its clinical efficacy.

Differences in outcomes for patients with bacteremia due to vancomycin-resistant Enterococcus faecium or vancomycin-susceptible E. faecium.

To determine the differences in outcome in cases of enterococcal bacteremia due to vancomycin-resistant organisms, we compared consecutive patients on a liver transplant service who had clinically significant bacteremia due to vancomycin-resistant Enterococcus faecium (VREF) (n = 54) with a contemporaneous cohort of patients who had vancomycin-susceptible E. faecium (VSEF) bacteremia (n = 48). VREF bacteremia occurred significantly later in the hospitalization than did VSEF bacteremia (43 days vs. 24 days, respectively; P < .01); in addition, VREF was more frequently the sole blood pathogen isolated (91% of patients) than was VSEF (56% of patients) (P = .0002). Invasive interventions for intraabdominal and intrathoracic infection were required more often in the VREF cohort than in the VSEF cohort (34 of 45 patients vs. 20 of 41 patients, respectively; P = .01). Vancomycin resistance more frequently resulted in recurrent bacteremia (22 of 54 patients infected with VREF vs. 7 of 48 patients infected with VSEF; P = .006), persistent isolation of Enterococcus species at the primary site (27 of 33 patients infected with VREF vs. 7 of 18 patients infected with VSEF; P = .005), and endovascular infection (4 patients infected with VREF vs. none infected with VSEF). The decrement in patient survival, as measured from the last bacteremic episode, was greater in the VREF cohort (P = .02). Vancomycin resistance, shock, and liver failure were independent risk factors for Enterococcus-associated mortality. Higher rates of refractory infection, serious morbidity, and attributable death occurred in the VREF cohort and were partially mediated by the lack of effective antimicrobial therapy.

Vancomycin-resistant Staphylococcus aureus: perspectives on measures needed for control.

Given the dramatic increase in the incidence of vancomycin resistance among the enterococci and experimental evidence for the transfer of vancomycin resistance from enterococci to Staphylococcus aureus, there is concern that strains of S. aureus will emerge that are resistant to vancomycin. The result would be a highly virulent pathogen for which effective antimicrobial therapy would not be available. To prevent the nosocomial transmission of such an organism, stringent infection control policies need to be developed and implemented. We offer proposals that are based on the limited data available on the transmission and control of S. aureus and that may be used as starting points for the development of formal guidelines for the isolation of colonized and infected patients and for microbiology laboratory precautions.

Antibiotic-resistant Acinetobacter meningitis in neurosurgical patients.

Acinetobacter anitratus has emerged as one of the common pathogens responsible for postneurosurgical meningitis at the authors' institution. Seven patients with Acinetobacter meningitis were identified during the 4-year period of this study, five of whom acquired organisms susceptible only to imipenem and amikacin. Acinetobacter bacteremia occurred concomitantly in five patients. Despite late institution of therapy as a result either of organism misidentification on Gram stain or of unexpected acquisition of a highly resistant organism, the patients' outcome was favorable after the initiation of appropriate antibiotic therapy. Imipenem and amikacin, with or without intrathecal aminoglycosides, were effective in patients with resistant strains of Acinetobacter.

Candida carriage in the alimentary tract of liver transplant candidates.

Thirty randomly selected patients with advanced chronic liver disease, which had been evaluated for possible liver transplantation, were sampled endoscopically at 7 alimentary tract locations to assess the frequency and amount of Candida carriage. Eighty-one percent (127/156) of the samples obtained contained Candida and 53% (82/156) yielded high counts (> 300 CFU/ml). The most predominant Candida species isolated at each site was Candida albicans, which accounted for 103 (64%) of the 160 fungal isolates. The other Candida species isolated included C tropicalis 30 (19%), C krusei 16 (10%), and C glabrata 11 (7%). Although the number of sites at which yeast was present and the quantities of yeast at each site varied widely among the patients studied, 100% of the patients had Candida in at least one site of the gastrointestinal tract. Eighty-six percent (24/28) of the duodenal aspirates contained Candida and 50% (14/28) of the duodenal samples contained greater than 300 CFU/ml. A positive culture from the stomach was a reliable predictor of the presence of Candida in the duodenum (P = 0.0001), but a positive culture at no other site readily predicted the presence of Candida at yet another site. Importantly, there was no correlation between the presence or absence of Candida in either oral or rectal swabs and colonization at other anatomic sites within the gastrointestinal tract. These findings are important in liver transplantation, particularly in those cases in which the bowel has been opened to create a choledochojejunostomy anastomosis. The operative attempts to reduce gastrointestinal fungal carriage using oral antifungal agents may be justified before liver transplantation in an effort to lower the risk of posttransplantation fungal infections, particularly in those patients expected to have a Roux-en-Y choledochojejunostomy biliary reconstruction.

Magnetic resonance imaging can cause focal heating in a nonuniform phantom.

To test if the radiofrequency fields of a magnetic resonance imager could cause focal heating, two cylindrical phantoms were made from a mixture of agar and saline. The first phantom was uniform; the second was nonuniform in that a narrow bridge of agar was produced. Both phantoms were exposed to high levels of radiofrequency power (140 W) at 63 MHz and the temperature rises were measured. In the uniform phantom, the temperature increased as the radius increased. In the bridge phantom, the narrow bridge heated three times greater than at the opposite uniform periphery, and over five times the average of the uniform phantom. This experiment demonstrates that the radiofrequency fields of magnetic resonance imagers can cause focal heating if the exposed object is nonuniform. Since nonuniformity is present in the human body, as the radiofrequency power of magnetic resonance imaging techniques increases, focal heating in patients is a concern.

Nosocomial outbreak of tuberculosis in a renal transplant unit: application of a new technique for restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolates.

From January 1990 through February 1991, tuberculosis (TB) developed in 10 renal transplant (RT) patients at one hospital; 5 patients died. Possible nosocomial transmission was investigated. Mycobacterium tuberculosis isolates were compared by restriction fragment length polymorphism (RFLP) by a polymerase chain reaction method. The source case occurred in an RT patient (source) who had posttransplant exposure to TB at another hospital. The source patient was rehospitalized on the RT unit; diagnosis of TB and thus isolation precautions were delayed. Epidemiologic and RFLP analysis showed transmission from the source to 5 RT patients and 1 human immunodeficiency virus-infected patient. M. tuberculosis isolates from 4 RT patients had other RFLP patterns. The median incubation period for TB in RT patients was 7.5 weeks (range, 5-11). Bronchoscopy and intubation of the source patient and inadequate ventilation on the RT unit possibly increased transmission. Early detection of TB and effective isolation are essential to prevent nosocomial transmission.

A Flavobacterium meningosepticum outbreak among intensive care patients.

A Flavobacterium meningosepticum outbreak, involving 12 infected and 47 colonized intensive care patients during the months of February through July 1990, was investigated. F. meningosepticum was isolated from tap water and ice, but these environmental strains eventually proved to be distinct from those colonizing patients. A review of newly colonized patients' charts revealed that a common factor among the patients was daily changes of ventilator tubing pasteurized in the hospital's central sterile department. More than 90% of patients in the outbreak had been on ventilators that used the pasteurized tubing. An investigation of the pasteurization process found that two pasteurizer tanks had been operating at suboptimal temperatures (< 62 degrees C). Cultures of water from the tanks and droplets of water found in the pasteurized tubing grew species of Acinetobacter, Moraxella, and Pseudomonas but did not grow F. meningosepticum. After deficiencies in the pasteurization process were corrected, the outbreak terminated. Despite the failure to culture F. meningosepticum, an analysis of gram-negative bacillary isolates showed that the deficiency in the pasteurization process was a major contributor to colonization of ventilated patients by bacteria ubiquitous in tap water.

Constitutively vancomycin-resistant Enterococcus faecium resistant to synergistic beta-lactam combinations.

Vancomycin resistance among enterococci has recently been recognized. Synergy between vancomycin and penicillin has been shown in vitro for isolates of Enterococcus faecium resistant to both of these antibiotics. We describe three isolates of vancomycin-resistant E. faecium which demonstrate unique phenotypic characteristics. The isolates exhibited high-level resistance to both vancomycin and teicoplanin, consistent with the VanA phenotype. However, resistance in these isolates could not be induced or cured, and mating experiments failed to detect a transfer of resistance. The combination of vancomycin and penicillin did not significantly change the MIC of penicillin for any of the three isolates. Immunoblotting with polyclonal anti-VanB antibody showed no reaction with the cellular proteins of these strains. Probing with a vanA oligonucleotide revealed hybridization with chromosomal but not plasmid DNA. The mechanism of constitutive resistance of those strains remains unclear. A second mutational change, perhaps involving PBP 5, may explain the presence of resistance to synergistic combination penicillin-vancomycin therapy. In vitro evaluation of penicillin-vancomycin should be carried out in all clinical cases where this therapeutic regimen is being considered.

Agrobacterium radiobacter: a recently recognized opportunistic pathogen.

Over the past decade, an increasing number of infections due to Agrobacterium radiobacter have been reported. Observation of three cases of bacteremia due to this organism prompted a review of the English-language literature. Nineteen cases of significant disease have previously been reported. In more than one-half of the cases, bacteremia was the primary manifestation, often associated with the presence of an intravascular catheter. Other clinical syndromes (peritonitis, urinary tract infection, and endocarditis) have been described. Infection is strongly related to the presence of plastic foreign material, and effective treatment often requires removal of the device. Because antimicrobial sensitivity is variable, treatment must be based on sensitivity data for the individual isolate.

Donor-transmitted pneumonia in experimental lung allografts. Successful prevention with donor antibiotic therapy.

Bacterial pneumonia is the most common cause of early morbidity and mortality (less than 2 weeks) after heart-lung transplantation. The majority (76%) of cultures taken from human donor tracheas at the time of explant grew bacteria. The abnormal immune response of the lung allograft and the common finding of bacterial contamination of lung donors led us to hypothesize that clinically silent bacterial contamination of the donor lung progresses to pneumonia in the recipient and that antibiotic treatment of donors will prevent the development of pneumonia in the recipient. Inocula of Streptococcus pneumoniae were instilled into the left middle lobe of normal and donor dogs to identify the number of bacteria that would result in pneumonia in a normal animal and the amount that, when given to a donor, would result in pneumonia in the recipient. Initial studies established that inocula of 10(4) colony-forming units of S. pneumoniae did not result in pneumonia in normal or immunosuppressed animals. When 10(4) colony-forming units or as few as 10(2) were instilled into the left middle lobe of donors 24 hours before explantation and use of the lung for transplantation, severe acute bronchopneumonia developed in all 18 recipients. Treatment of donors with aerosol and intravenous antibiotics, but not with either alone, prevented pneumonia in the recipients. We conclude that bacterial contamination of the donor lung leads to pneumonia in recipients. Intravenous and aerosol antibiotic treatment of donors with bacterial contamination prevents pneumonia in canine lung recipients. Treatment of human donors with this antibiotic regimen may decrease the prevalence of early bacterial pneumonia.

Clinical evaluation of autotransfusion during liver transplantation.

The clinical suitability of intraoperative autotransfusion was evaluated in 25 patients undergoing orthotopic liver transplantation using a Cell Saver #4 (Haemonetics) with acid-citrate-dextrose anticoagulation. In the first 14 patients (phase 1), biochemical, hematologic, coagulation, and semiquantitative bacteriologic studies were performed from the collected blood, processed blood, and patients' blood before and after 500 mL of autotransfusion. The acid-citrate-dextrose solution produced adequate anticoagulation, and the system effectively removed most of the potassium, red blood cell fragments, plasma free hemoglobin, bilirubin, coagulation factors, platelets, and fibrin degradation products. Autotransfusion (500 mL) did not alter coagulation, electrolyte balance, and hematologic findings in recipients except for a clinically insignificant increase in plasma free hemoglobin. Seventeen of 56 samples of the collected blood or processed blood were positive for coagulase (-) Staphylococcus (occasional or rare), but blood cultures before and after autotransfusion were negative in all patients. In the next 11 patients (phase 2), a quantitative bacteriologic study was performed from the collected blood, processed blood, skin, bile duct stump, peritoneal cavity, and room air using a mock reservoir. The processed blood was not transfused. All blood cultures from the patients were sterile. However, coagulase (-) Staphylococcus or Bacillus sp was seen in two cultures from skin, three from the processed blood, and three from air, suggesting that room air and skin were the sources of contamination. When the patients of the two phases of study were compared, postoperative blood cultures were all sterile, and renal function was similar. Therefore, autotransfusion appears to be clinically acceptable during liver transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Extragenital Mycoplasma hominis infections in adults.

PURPOSE: To heighten awareness of the role of Mycoplasma hominis as an extragenital pathogen in adults. PATIENTS AND METHODS AND RESULTS: Patients ranged in age from 14 to 76 years. Thirteen patients were immunosuppressed, including nine organ transplant recipients; three were receiving steroids, and two had an underlying malignancy. The remainder were immunocompetent. Thirteen patients had prior surgery at or near the site of infection. M. hominis was isolated from normally sterile sites such as blood or cerebrospinal, pleural, abdominal and joint fluids, and bone. Non-sterile sites of isolation included surgical wounds and pulmonary secretions. The organism was detected in anaerobic cultures of clinical specimens sent to the laboratory for routine bacteriologic culture. Gram stains of fluids or wound drainage revealed neutrophils but no bacteria. Anti-mycoplasmal therapy was effective in eradicating the organism in 13 of 15 patients who were treated. Of those in whom treatment failed, one patient had an antibiotic-resistant isolate and the other had M. hominis isolated from the lung at postmortem after just 2 days of therapy. CONCLUSION: Our experience suggests that significant infections due to M. hominis, although uncommon, are not rare, and methods to isolate and identify this organism should be available for general adult medical and surgical populations.

Laboratory and clinical evaluation of a commercial DNA probe for the detection of Legionella spp.

We prospectively compared a commercially available Legionella DNA probe with culture and direct immunofluorescence. The analytical sensitivities of the DNA probe and direct immunofluorescence were equal. Both tests detected 4 X 10(3) CFU of Legionella pneumophila or Legionella micdadei per ml in the pulmonary secretions of experimentally infected guinea pigs. The diagnostic sensitivity of the reagent was evaluated by using 809 samples of respiratory secretions. Of 51 DNA probe-positive specimens, 31 came from patients with culture-confirmed legionellosis. Two culture-positive specimens had negative DNA probe tests. The sensitivity and specificity of the DNA probe were 93.9 and 97.4%, respectively. The sensitivity and specificity of direct immunofluorescence were 68.9 and 99.6%, respectively. The low specificity of the DNA probe resulted in an unacceptable positive predictive value (60.8%). False-positive DNA probe tests were not due to nonspecific binding of the probe or to technical problems but were associated with one lot of probe reagent. Most of the false-positive probe tests had values near the threshold value of greater than or equal to 4.0 suggested by the manufacturer. Raising the threshold value for a positive test to 7 lowered the sensitivity to 69.2% but raised the specificity to 99.2%. At this level, the performances of the DNA probe and direct fluorescent-antibody testing were equivalent. Respiratory secretions from patients receiving therapy for culture-confirmed Legionella infection remained DNA probe positive for up to 8 days, even though cultures and/or direct immunofluorescence tests often became negative. The DNA probe test is a satisfactory replacement for direct immunofluorescence but cannot replace culture for the laboratory diagnosis of Legionella infections.

Legionella micdadei phosphatase catalyzes the hydrolysis of phosphatidylinositol 4,5-bisphosphate in human neutrophils.

The legionellae are facultative intracellular bacterial pathogens which multiply in host phagocytes. Legionella micdadei cells contain an acid phosphatase (ACP2) which blocks superoxide anion production by human neutrophils stimulated with formyl-Met-Leu-Phe (fMLP) [A. K. Saha, et al. (1985) Arch. Biochem. Biophys. 243, 150-160]. In the present study, we have purified the Legionella phosphatase to homogeneity as indicated by the finding of a single 68,000-Da band following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We explored the possibility that ACP2 acts by interfering with polyphosphoinositide hydrolysis and the production of the intracellular second messengers, inositol trisphosphate (IP3) and diacylglycerol, following neutrophil stimulation. Phosphatidylinositol 4,5-bisphosphate (PIP2) was hydrolyzed rapidly by ACP2 in vitro. The rate of hydrolysis of PIP2 was higher at pH 7.0 (Km 2.0 microM; 4 X 10(3) units/mg protein; 1 unit equals 1 nmol of Pi released/h) than at lower pH. IP3 was also a good substrate for ACP2 in vitro. When human neutrophil phosphoinositides were prelabeled with 32Pi, subsequent incubation with ACP2 resulted in an 85% loss of the labeled PIP2 over 2 h. Following fMLP stimulation of [3H]inositol-labeled neutrophils, the quantity of IP3 produced by ACP2-treated cells was reduced by 44%. Prior treatment of neutrophils with ACP2 also reduced by 45% the amount of diacylglycerol they produced when stimulated by fMLP. These results indicate that the Legionella phosphatase may compromise the neutrophils' microbicidal response to the organism by hydrolyzing PIP2, the progenitor of IP3 and diacylglycerol, and by hydrolyzing IP3 itself.

Pathogenesis and pathology of legionellosis.

Infection with members of the genus Legionella can produce a wide spectrum of disease ranging from a self-limiting febrile illness to life-threatening pneumonia. The primary site of infection in the pneumonic form of the disease appears to be the lung, but dissemination to other organs is possible. Infection results in an intense alveolitis with infiltration by large numbers of mixed inflammatory cells. The legionellae are facultative intracellular pathogens which multiply within host phagocytic cells, primarily alveolar macrophages, and disrupt the bactericidal mechanisms of these cells. The role of the polymorphonuclear leukocyte is less clearly understood. Many members of the genus produce a number of toxins which may be responsible for some of the pulmonary and extrapulmonary manifestations of disease.