Janet E. Stout

Distribution of Legionella Species and Serogroups Isolated by Culture in Patients with Sporadic Community-Acquired Legionellosis: An International Collaborative Survey

This international collaborative survey identified culture-confirmed legionellosis in 508 patients with sporadic community-acquired legionellosis. Legionella pneumophila constituted 91.5% of the isolates. Serogroup 1 was the predominant serogroup (84.2%), and serogroups 2-13 (7.4%) accounted for the remaining serogroups. The Legionella species most commonly isolated were L. longbeachae (3.9%) and L. bozemanii (2.4%), followed by L. micdadei, L. dumoffii, L. feeleii, L. wadsworthii, and L. anisa (2.2% combined). L. longbeachae constituted 30.4% of the community-acquired Legionella isolates in Australia and New Zealand.

Prospective Assessment of Platelia™ Aspergillus Galactomannan Antigen for the Diagnosis of Invasive Aspergillosis in Lung Transplant Recipients

The clinical utility of Platelia™Aspergillus galactomannan antigen for the early diagnosis of invasive aspergillosis was prospectively assessed in 70 consecutive lung transplant recipients. Sera were collected twice weekly and tested for galactomannan. Invasive aspergillosis was documented in 17.1% (12/70) of the patients. Using the generalized estimating equation model, at the cutoff value of ≥ 0.5, the sensitivity of the test was 30%, specificity 93% with positive and negative likelihood ratios of 4.2 and 0.75, respectively. Increasing the cutoff value to ≥ 0.66 yielded a sensitivity of 30%, specificity of 95%, and positive and negative likelihood ratios of 5.5 and 0.74. A total of 14 patients had false‐positive tests, including nine who had cystic fibrosis or chronic obstructive pulmonary disease. False‐positive tests occurred within 3 days of transplantation in 43% (6/14) of the patients, and within 7 days in 64% (9/14). Thus, the test demonstrated excellent specificity, but a low sensitivity for the diagnosis of aspergillosis in this patient population. Patients with cystic fibrosis or chronic obstructive pulmonary disease may transiently have a positive test in the early post‐transplant period.

Efficacy of Galactomannan Antigen in the Platelia Aspergillus Enzyme Immunoassay for Diagnosis of Invasive Aspergillosis in Liver Transplant Recipients

ABSTRACT The utility of galactomannan antigen for diagnosing invasive aspergillosis was evaluated in 154 liver transplant recipients. Sample agreement was 98.5%, and patient specificity was 87%. Galactomannan positivity correlated with mortality, even when controlled for the number of tests performed. Whether galactomannan positivity identifies a subgroup at risk for poor outcome warrants further evaluation.

Individual and combined effects of copper and silver ions on inactivation of Legionella pneumophila

Abstract Copper/silver ionization is a new disinfection method that is being used to eradicate Legionella pneumophila from hospital hot water recirculating systems. The objective of this study was to determine the susceptibility of L. pneumophila serogroup 1 to copper and silver ions alone and in combination. L. pneumophila serogroup 1 ( L. p. sg-1) was completely inactivated (6-log reduction) at copper concentration of 0.1 mg/l within 2.5 h, whereas more than 24 h was required to achieve a similar reduction at the highest silver ion concentration tested (0.08 mg/l). Checkerboard method and Gard additive model prediction demonstrated that copper and silver ions in combination could result in additive or synergistic effect depending on the concentration of copper and silver ions. Under the experimental conditions used in this study, synergism of copper/silver ions in eradicating L. p. sg-1 was observed at higher concentration combinations of copper/silver ions (e.g. 0.04/0.04 mg/l) while only an additive effect was observed at lower concentration combinations (e.g. 0.02/0.02 mg/l). This study suggested that both copper and silver ions are effective in inactivating L. pneumophila and the combined effect is greater than that seen with either ion alone.

Isolation of Staphylococcus aureus from the Urinary Tract: Association of Isolation with Symptomatic Urinary Tract Infection and Subsequent Staphylococcal Bacteremia

BACKGROUND Staphylococcus aureus is frequently isolated from urine samples obtained from long-term care patients. The significance of staphylococcal bacteriuria is uncertain. We hypothesized that S. aureus is a urinary pathogen and that colonized urine could be a source of future staphylococcal infection. METHODS We performed a cohort study of 102 patients at a long-term care Veterans Affairs facility for whom S. aureus had been isolated from clinical urine culture. Patients were observed via urine and nasal cultures that were performed every 2 months. We determined the occurrence of (1) symptomatic urinary tract infection concurrent with isolation of S. aureus (by predetermined criteria), (2) staphylococcal bacteremia concomitant with isolation of S. aureus from urine, and (3) subsequent episodes of staphylococcal infection. RESULTS Of 102 patients, 82% had undergone recent urinary catheterization. Thirty-three percent of patients had symptomatic urinary tract infection at the time of initial isolation of S. aureus, and 13% were bacteremic. Eight-six percent of the initial urine isolates were methicillin-resistant S. aureus. Seventy-one patients had follow-up culture data; 58% of cultures were positive for S. aureus at > or =2 months (median duration of staphylococcal bacteriuria, 4.3 months). Sixteen patients had subsequent staphylococcal infections, occurring up to 12 months after initial isolation of S. aureus; 8 late-onset infections were bacteremic. In 5 of 8 patients, the late blood isolate was found to have matched the initial urine isolate by pulsed-field gel electrophoresis typing. CONCLUSIONS S. aureus is a cause of urinary tract infection among patients with urinary tract catheterization. The majority of isolates are methicillin-resistant S. aureus. S. aureus bacteriuria can lead to subsequent invasive infection. The efficacy of antistaphylococcal therapy in preventing late-onset staphylococcal infection in patients with persistent staphylococcal bacteriuria should be tested in controlled trials.

Role of Environmental Surveillance in Determining the Risk of Hospital-Acquired Legionellosis: A National Surveillance Study With Clinical Correlations

OBJECTIVE Hospital-acquired Legionella pneumonia has a fatality rate of 28%, and the source is the water distribution system. Two prevention strategies have been advocated. One approach to prevention is clinical surveillance for disease without routine environmental monitoring. Another approach recommends environmental monitoring even in the absence of known cases of Legionella pneumonia. We determined the Legionella colonization status of water systems in hospitals to establish whether the results of environmental surveillance correlated with discovery of disease. None of these hospitals had previously experienced endemic hospital-acquired Legionella pneumonia. DESIGN Cohort study. SETTING Twenty US hospitals in 13 states. INTERVENTIONS Hospitals performed clinical and environmental surveillance for Legionella from 2000 through 2002. All specimens were shipped to the Special Pathogens Laboratory at the Veterans Affairs Pittsburgh Medical Center. RESULTS Legionella pneumophila and Legionella anisa were isolated from 14 (70%) of 20 hospital water systems. Of 676 environmental samples, 198 (29%) were positive for Legionella species. High-level colonization of the water system (30% or more of the distal outlets were positive for L. pneumophila) was demonstrated for 6 (43%) of the 14 hospitals with positive findings. L. pneumophila serogroup 1 was detected in 5 of these 6 hospitals, whereas 1 hospital was colonized with L. pneumophila serogroup 5. A total of 633 patients were evaluated for Legionella pneumonia from 12 (60%) of the 20 hospitals: 377 by urinary antigen testing and 577 by sputum culture. Hospital-acquired Legionella pneumonia was identified in 4 hospitals, all of which were hospitals with L. pneumophila serogroup 1 found in 30% or more of the distal outlets. No cases of disease due to other serogroups or species (L. anisa) were identified. CONCLUSION Environmental monitoring followed by clinical surveillance was successful in uncovering previously unrecognized cases of hospital-acquired Legionella pneumonia.

Staphylococcus aureus rectal carriage and its association with infections in patients in a surgical intensive care unit and a liver transplant unit.

BACKGROUND The role of rectal carriage of Staphylococcus aureus as a risk factor for nosocomial S. aureus infections in critically ill patients has not been fully discerned. METHODS Nasal and rectal swabs for S. aureus were obtained on admission and weekly thereafter until discharge or death from 204 consecutive patients admitted to the surgical intensive care unit and liver transplant unit RESULTS Overall, 49.5% (101 of 204) of the patients never harbored S. aureus, 21.6% (44 of 204) were nasal carriers only, 3.4% (7 of 204) were rectal carriers only, and 25.5% (52 of 204) were both nasal and rectal carriers. Infections due to S. aureus developed in 15.7% (32 of 204) of the patients; these included 3% (3 of 101) of the non-carriers, 18.2% (8 of 44) of the nasal carriers only, 0% (0 of 7) of the rectal carriers only, and 40.4% (21 of 52) of the patients who were both nasal and rectal carriers (P - .001). Patients with both rectal and nasal carriage were significantly more likely to develop S. aureus infection than were those with nasal carriage only (odds ratio, 3.9; 95% confidence interval, 1.18 to 7.85; P= .025). By pulsed-field gel electrophoresis, the infecting rectal and nasal isolates were clonally identical in 82% (14 of 17) of the patients with S. aureus infections. CONCLUSIONS Rectal carriage represents an underappreciated reservoir for S. aureus in patients in the intensive care unit and liver transplant recipients. Rectal plus nasal carriage may portend a greater risk for S. aureus infections in these patients than currently realized.

Reactivity of Platelia Aspergillus Galactomannan Antigen with Piperacillin-Tazobactam: Clinical Implications Based on Achievable Concentrations in Serum

ABSTRACT The possible reactivities of commonly used antibiotics of fungal, nonfungal, and nonmicrobial or synthetic sources with the Platelia Aspergillus galactomannan assay were assessed. For drugs that tested positive, the minimal concentration of the antibiotic in serum that yielded a positive test (index, >0.5) was determined. At undiluted concentrations, piperacillin and multiple lots of piperacillin-tazobactam tested positive, whereas amoxicillin, ampicillin-sulbactam, nafcillin, cefazolin, ceftazidime, erythromycin, gentamicin, and levofloxacin tested negative. All three lots of piperacillin-tazobactam and all bags within each lot tested positive, with a mean index value of 5.168. At achievable concentrations in serum, however, only one of three lots of piperacillin-tazobactam yielded a positive test. Concentrations of 75, 150, and 300 μg/ml of serum tested positive with the Platelia Aspergillus enzyme immunoassay, whereas lower concentrations, mimicking the trough levels, tested negative. Thus, while achievable serum piperacillin-tazobactam concentrations may potentially result in a positive test for galactomannan, the timing of the collection of serum samples from patients may influence the test results, with reactivity being less likely in samples collected at trough levels or prior to the administration of a dose of the antibiotic.

Thrombocytopenia in liver transplant recipients: predictors, impact on fungal infections, and role of endogenous thrombopoietin.

BACKGROUND Thrombocytopenia is a frequent and potentially serious complication in liver transplant recipients. The role of endogenous thrombopoietin level in posttransplant thrombocytopenia, has not been fully defined in liver transplant recipients. Additionally, there is accumulating evidence to suggest that platelets play a important role in antimicrobial host defense. METHODS There were 50 consecutive liver transplant recipients studied. Variables predictive of thrombocytopenia, its impact on infectious morbidity and outcome, and serial thrombopoietin (TPO) serum concentration were assessed. RESULTS The median pretransplant platelet count was 67 x 10(3)/cmm. After the liver transplantation, the median nadir platelet count was 33 x 10(3)/cmm and was reached a mean of 6 days after the transplant. A lower pretransplant platelet count (r= +.068, P=.0001), lower serum albumin before the transplants (r=+0.39, P=.014), longer operation time (r=0.27, P=.05), higher intraoperative packed red cells (r=0.28, P=.049) and fresh frozen plasma transfusions (r=0.42, P=.004), higher bilirubin at Day 7 (r=-.386, P=.005), and higher serum creatinine at Day 7 after the transplants (r=-.031, P=.025) correlated significantly with a lower nadir in platelets after the transplant. Nadir in platelet count was significantly lower in nonsurvivors compared with survivors (16 vs. 36 x 10(3)/cmm, P=.0001). Forty-three percent (9 of 21) of the patients with nadir platelet counts of < or =30 x 10(3)/cmm had a major infection within 30 days of the transplant compared with 17% (5 of 29) with nadir platelet counts > 30 x 10(3)/cmm (P=.04). Fungal infections occurred in 14% of the patients with nadir platelet counts of < or =30 x 10(3)/cmm versus 0% in those with nadir platelet counts of > 30 x 10(3)/cmm (P=.06); all patients with fungal infections had nadir platelet counts of < or =30 x 10(3)/cmm before fungal infection. Nadir in platelet count preceded the first major infection by a median of 7 days. Pretransplant TPO level did not differ between survivors (mean 103 pg/ml) or nonsurvivors (mean 144 pg/ml). After the transplantation, TPO levels increased in both groups. TPO level peaked at Day 7 and subsequently declined in survivors. Nonsurvivors had persistent thrombocytopenia despite a progressive rise in TPO level; TPO level was significantly higher at Day 7 (P=.02), Day 9 (P=.0019), and Day 14 (P=.04) in nonsurvivors compared with survivors. CONCLUSION Persistent thrombocytopenia portended a poor outcome in liver transplant recipients and was not related to low TPO levels. Thrombocytopenia preceded infections and identified a subgroup of liver transplant patients susceptible to early major infections; its precise role in fungal infections warrants validation in larger studies.

Negative Effect of High pH on Biocidal Efficacy of Copper and Silver Ions in Controlling Legionella pneumophila

ABSTRACT Copper-silver (Cu-Ag) ionization has effectively controlled Legionella spp. in the hot water systems of numerous hospitals. However, it was ineffective at controlling Legionella in one Ohio hospital despite the confirmation of adequate total concentrations of copper and silver ions. The pH of the water at this hospital was found to be 8.5 to 9.0. The purpose of this study was to investigate the impact of pH and other water quality parameters, including alkalinity (HCO3−), hardness (Ca2+ and Mg2+), and amount of dissolved organic carbon (DOC), on the control of Legionella by Cu-Ag ionization. Initial concentrations of Legionella and copper and silver ions used in batch experiments were 3 × 106 CFU/ml and 0.4 and 0.08 mg/liter, respectively. Changes in bicarbonate ion concentration (50, 100, and 150 mg/liter), water hardness (Ca2+ at 50 and 100 mg/liter; Mg2+ at 40 and 80 mg/liter), and level of DOC (0.5 and 2 mg/liter) had no significant impact on the efficacy of copper and silver ions in killing Legionella at a neutral pH. When the pH was elevated to 9 in these experiments, copper ions achieved only a 10-fold reduction in the number of Legionella organisms in 24 h, compared to a millionfold decrease at pH 7.0. Silver ions were able to achieve a millionfold reduction in 24 h at all ranges of water quality parameters tested. Precipitation of insoluble copper complexes was observed at a pH above 6.0. These results suggest that pH may be an important factor in the efficacy of copper-silver ionization in controlling Legionella in water systems.