Looking Beyond Respiratory Cultures: Microbiome-Cytokine Signatures of Bacterial Pneumonia and Tracheobronchitis in Lung Transplant Recipients

Bacterial pneumonia and tracheobronchitis are diagnosed frequently following lung transplantation. The diseases share clinical signs of inflammation and are often difficult to differentiate based on culture results. Microbiome and host immune-response signatures that distinguish between pneumonia and tracheobronchitis are undefined. Using a retrospective study design, we selected 49 bronchoalveolar lavage fluid samples from 16 lung transplant recipients associated with pneumonia (n = 8), tracheobronchitis (n = 12) or colonization without respiratory infection (n = 29). We ensured an even distribution of Pseudomonas aeruginosa or Staphylococcus aureus culture-positive samples across the groups. Bayesian regression analysis identified non-culture-based signatures comprising 16S ribosomal RNA microbiome profiles, cytokine levels and clinical variables that characterized the three diagnoses. Relative to samples associated with colonization, those from pneumonia had significantly lower microbial diversity, decreased levels of several bacterial genera and prominent multifunctional cytokine responses. In contrast, tracheobronchitis was characterized by high microbial diversity and multifunctional cytokine responses that differed from those of pneumonia-colonization comparisons. The dissimilar microbiomes and cytokine responses underlying bacterial pneumonia and tracheobronchitis following lung transplantation suggest that the diseases result from different pathogenic processes. Microbiomes and cytokine responses had complementary features, suggesting that they are closely interconnected in the pathogenesis of both diseases.

Safety and tolerability of clofazimine as salvage therapy for atypical mycobacterial infection in solid organ transplant recipients

BACKGROUND

The treatment of Mycobacterium avium complex (MAC) requires prolonged, multidrug therapy, which is often not well tolerated. In solid organ transplant (SOT) recipients, drug-drug interactions complicate treatment further. Failure or intolerance requires the use of salvage regimens, and clofazimine is one of the drugs that can be used. No data are available on the safety and tolerability of clofazimine for the treatment of MAC in SOT recipients.

METHODS

Retrospective review of all SOT recipients treated for MAC infection with clofazimine at a large transplant center between 2006 and 2013.

RESULTS

Five SOT recipients received clofazimine as salvage therapy. Transplanted organs were lungs in 3 patients, and kidney and liver in 1 patient each. Infection was diagnosed at a median of 22 months (range 4-57) post transplant. Sites of infection were the lungs in 2 patients, and septic arthritis, mesenteric, and disseminated disease in 1 patient each. All patients received standard anti-MAC therapy for a median of 26 weeks (range 18-45) before starting clofazimine. Indications for use of clofazimine included a lack of response to previous therapy (3 patients), and poor tolerance of other regimens (3 patients). All patients received at least 2 additional drugs besides clofazimine. Median duration of clofazimine-containing regimen was 8 months (range 2-18). Clofazimine was discontinued because of gastrointestinal intolerance in 1 of the 5 patients. The most common adverse event from clofazimine was skin discoloration, in 60% of patients. No hepatotoxicity or hematologic toxicity occurred. Microbiological clearance and resolution of clinical disease was documented in 2 of 5 patients; and 2 of the 5 patients died of other causes while on therapy.

CONCLUSIONS

Clofazimine appears safe and may be considered as a salvage therapeutic option in SOT recipients with MAC infection who are intolerant or unresponsive to standard therapy. The small sample size does not allow conclusions regarding efficacy.

Targeted versus universal antifungal prophylaxis among liver transplant recipients

Guidelines recommend targeted antifungal prophylaxis for liver transplant (LT) recipients based on tiers of risk, rather than universal prophylaxis. The feasibility and efficacy of tiered, targeted prophylaxis is not well established. We performed a retrospective study of LT recipients who received targeted prophylaxis (n = 145; voriconazole [VORI; 54%], fluconazole [8%], no antifungal [38%]) versus universal VORI prophylaxis (n = 237). Median durations of targeted and universal prophylaxis were 11 and 6 days, respectively (p < 0.0001). The incidence of invasive fungal infections (IFIs) in targeted and universal groups was 6.9% and 4.2% (p = 0.34). Overall, intra-abdominal candidiasis (73%) was the most common IFI. Posttransplant bile leaks (p = 0.001) and living donor transplants (p = 0.04) were independent risk factors for IFI. IFIs occurred in 6% of high-risk transplants who received prophylaxis and 4% of low-risk transplants who did not receive prophylaxis (p = 1.0). Mortality rates (100 days) were 10% (targeted) and 7% (universal) (p = 0.26); attributable mortality due to IFI was 10%. Compliance with prophylaxis recommendations was 97%. Prophylaxis was discontinued for toxicity in 2% of patients. Targeted antifungal prophylaxis in LT recipients was feasible and safe, effectively prevented IFIs and reduced the number of patients exposed to antifungals. Bile leaks and living donor transplants should be considered high-risk indications for prophylaxis.

Histoplasmosis after solid organ transplant

BACKGROUND

To improve our understanding of risk factors, management, diagnosis, and outcomes associated with histoplasmosis after solid organ transplant (SOT), we report a large series of histoplasmosis occurring after SOT.

METHODS

All cases of histoplasmosis in SOT recipients diagnosed between 1 January 2003 and 31 December 2010 at 24 institutions were identified. Demographic, clinical, and laboratory data were collected.

RESULTS

One hundred fifty-two cases were identified: kidney (51%), liver (16%), kidney/pancreas (14%), heart (9%), lung (5%), pancreas (2%), and other (2%). The median time from transplant to diagnosis was 27 months, but 34% were diagnosed in the first year after transplant. Twenty-eight percent of patients had severe disease (requiring intensive care unit admission); 81% had disseminated disease. Urine Histoplasma antigen detection was the most sensitive diagnostic method, positive in 132 of 142 patients (93%). An amphotericin formulation was administered initially to 73% of patients for a median duration of 2 weeks; step-down therapy with an azole was continued for a median duration of 12 months. Ten percent of patients died due to histoplasmosis with 72% of deaths occurring in the first month after diagnosis; older age and severe disease were risk factors for death from histoplasmosis. Relapse occurred in 6% of patients.

CONCLUSIONS

Although late cases occur, the first year after SOT is the period of highest risk for histoplasmosis. In patients who survive the first month after diagnosis, treatment with an amphotericin formulation followed by an azole for 12 months is usually successful, with only rare relapse.

Epidemiology and outcomes of deep surgical site infections following lung transplantation

We conducted a retrospective study of deep surgical site infections (SSIs) among consecutive patients who underwent lung transplantation (LTx) at a single center from 2006 through 2010. Thirty-one patients (5%) developed SSIs at median 25 days after LTx. Empyema was most common (42%), followed by surgical wound infections (29%), mediastinitis (16%), sternal osteomyelitis (6%), and pericarditis (6%). Pathogens included Gram-positive bacteria (41%), Gram-negative bacteria (41%), fungi (10%) and Mycobacterium abscessus, Mycoplasma hominis and Lactobacillus sp. (one each). Twenty-three percent of SSIs were due to pathogens colonizing recipients' native lungs at time of LTx, suggesting surgical seeding as a source. Patient-related independent risk factors for SSIs were diabetes and prior cardiothoracic surgery; procedure-related independent risk factors were LTx from a female donor, prolonged ischemic time and number of perioperative red blood cell transfusions. Mediastinitis and sternal infections were not observed among patients undergoing minimally invasive LTx. SSIs were associated with 35% mortality at 1 year post-LTx. Lengths of stay and mortality in-hospital and at 6 months and 1 year were significantly greater for patients with SSIs other than empyema. In conclusion, deep SSIs were uncommon, but important complications in LTx recipients because of their diverse microbiology and association with increased mortality.

Epidemiology, clinical characteristics and outcomes of extensively drug-resistant Acinetobacter baumannii infections among solid organ transplant recipients

BACKGROUND

Extensively drug-resistant Acinetobacter baumannii (XDR-Ab) has emerged as a major nosocomial pathogen, but optimal treatment regimens are unknown. Although solid organ transplant (SOT) recipients are particularly susceptible to XDR-Ab infections, studies in this population are limited. Our objectives were to determine the epidemiology, clinical characteristics and outcomes of XDR-Ab infections among SOT patients.

METHODS

A retrospective study of SOT recipients at our center who were colonized or infected with XDR-Ab between November 2006 and December 2011 was conducted. Among infected patients, the primary outcome was survival at 28 days. Secondary outcomes included survival at 90 days and clinical success at 28 days, and XDR-Ab infection recurrence.

RESULTS

XDR-Ab was isolated from 69 SOT patients, of whom 41% (28) and 59% (41) were colonized and infected, respectively. Infections were significantly more common among cardiothoracic than abdominal transplant recipients (p=0.0004). Ninety-eight percent (40/41) of patients had respiratory tract infections, most commonly ventilator-associated pneumonia (VAP; 88% [36/41]). Survival rates at 28 and 90 days were 54% (22/41) and 46% (19/41), respectively. Treatment with a colistin-carbapenem regimen was an independent predictor of 28-day survival (p=0.01; odds ratio=7.88 [95% CI: 1.60-38.76]). Clinical success at 28 days was achieved in 49% (18/37) of patients who received antimicrobial therapy, but 44% (8/18) of successes were associated with infection recurrence within 3 months. Colistin resistance emerged in 18% (2/11) and 100% (3/3) of patients treated with colistin-carbapenem and colistin-tigecycline, respectively (p=0.03).

CONCLUSIONS

XDR-Ab causes VAP and other respiratory infections following SOT that are associated with significant recurrence and mortality rates. Cardiothoracic transplant recipients are at greatest risk. Results from this retrospective study suggest that colistin-carbapenem combinations may result in improved clinical responses and survival compared to other regimens and may also limit the emergence of colistin resistance.

Staphylococcus aureus infections in the early period after lung transplantation: epidemiology, risk factors, and outcomes

BACKGROUND

Staphylococcus aureus infections among lung transplant recipients are poorly studied.

METHODS

We conducted a 5-year retrospective study of the epidemiology, clinical manifestations, risk factors, and outcomes of patients infected with S aureus within the first 90 days after lung transplantation.

RESULTS

An S aureus infection developed in 109 of 596 lung transplant (18%) recipients. Methicillin-susceptible S aureus (MSSA; 62%) was more common than methicillin-resistant S aureus (MRSA; 38%); however, the proportion of infections caused by MRSA increased over time. Pneumonia (48%) was the most common infection, followed by tracheobronchitis (26%), bacteremia (12%), intrathoracic infections (7%), and skin/soft tissue infections (7%). Risk factors included mechanical ventilation for > 5 days and isolation of S aureus from recipients' sterility cultures. Patients with MRSA cultured from the nares or respiratory tract at the time of transplant were at an increased risk for MRSA infection (p < 0.0001 and p = 0.02, respectively). Infected patients required longer hospital and intensive care unit stays (p < 0.0001 for both), but the 30- and 90-day mortality rates from the onset of infection were only 7% and 12%, respectively. However, infected patients had higher rates of acute and chronic rejection at 1 (p = 0.048) and 3 years (p = 0.002), and higher rates of mortality at 1 (p = 0.058) and 3 years (p = 0.009).

CONCLUSIONS

S aureus infections within the first 90 days of lung transplant were associated with low short-term mortality but increased long-term rates of mortality and acute and chronic rejection. Future studies are needed to explore the utility of S aureus eradication strategies in reducing disease burden and improving outcomes.

Invasive aspergillosis among heart transplant recipients is rare but causes rapid death due to septic shock and multiple organ dysfunction syndrome

Between 2000 and 2011, proven or probable invasive aspergillosis (IA) was diagnosed in 1.7% (8/455) of heart transplant (HTx) recipients at our center, in the absence of antifungal prophylaxis. All patients had invasive pulmonary infections and 75% (6/8) were diagnosed during 2 separate 3-month periods. Cases were notable for their association with septic shock and multiple organ dysfunction syndrome (MODS) (75%, 6/8 each), non-specific clinical and radiographic findings, and rapid mortality despite mould-active antifungal therapy (88%, 7/8; occuring at a median 11 days after diagnosis). All patients had predisposing conditions known to be risk factors for IA. For patients with early IA (within 90 days of HTx), conditions included hemodialysis, thoracic re-operation, and the presence of another case in the institution within the preceding 3 months. For late-onset IA, conditions included hemodialysis and receipt of augmented immunosuppression. Clinicians should suspect IA in HTx recipients with risk factors who present with non-specific and unexplained respiratory syndromes, including those in septic shock and MODS, and institute prompt antifungal therapy without waiting for the results of cultures or other diagnostic tests.

Prospective, observational study of voriconazole therapeutic drug monitoring among lung transplant recipients receiving prophylaxis: factors impacting levels of and associations between serum troughs, efficacy, and toxicity

Voriconazole prophylaxis is common following lung transplantation, but the value of therapeutic drug monitoring is unknown. A prospective, observational study of lung transplant recipients (n = 93) receiving voriconazole prophylaxis was performed. Serum voriconazole troughs (n = 331) were measured by high-pressure liquid chromatography. The median initial and subsequent troughs were 1.91 and 1.46 μg/ml, respectively. The age of the patient directly correlated with initial troughs (P = 0.005). Patients that were ≥ 60 years old and cystic fibrosis patients were significantly more likely to have higher and lower initial troughs, respectively. In 95% (88/93) of patients, ≥ 2 troughs were measured. In 28% (25/88) and 32% (28/88) of these patients, all troughs were ≤ 1.5 μg/ml or >1.5 μg/ml, respectively. Ten percent (10/93) and 27% (25/93) of the patients developed invasive fungal infection (tracheobronchitis) and fungal colonization, respectively. The median troughs at the times of positive and negative fungal cultures were 0.92 and 1.72 μg/ml (P = 0.07). Invasive fungal infections or colonization were more likely with troughs of ≤ 1.5 μg/ml (P = 0.01) and among patients with no trough of >1.5 μg/ml (P = 0.007). Other cutoff troughs correlated less strongly with microbiologic outcomes. Troughs correlated directly with aspartate transferase levels (P = 0.003), but not with other liver enzymes. Voriconazole was discontinued due to suspected toxicity in 27% (25/93) of the patients. The troughs did not differ at the times of suspected drug-induced hepatotoxicity, central nervous system (CNS) toxicity, or nausea/vomiting and in the absence of toxicity. Voriconazole prophylaxis was most effective at troughs of >1.5 μg/ml. A cutoff for toxicity was not identified, but troughs of >4 μg/ml were rare. The data support a target range of >1.5 to 4 μg/ml.

High mortality rates among solid organ transplant recipients infected with extensively drug-resistant Acinetobacter baumannii: using in vitro antibiotic combination testing to identify the combination of a carbapenem and colistin as an effective treatment regimen

Extensively drug-resistant (XDR) Acinetobacter baumannii infections caused 91% (10/11) mortality in transplant recipients. Isolates were colistin-susceptible initially, but susceptibility decreased during therapy in 40% (4/10). We tested antibiotic combinations against XDR Acinetobacter in vitro and demonstrated positive interactions for carbapenem-colistin. Subsequently, 80% (4/5) of transplant patients were treated successfully with carbepenem-colistin regimens.

Voriconazole exposure and geographic location are independent risk factors for squamous cell carcinoma of the skin among lung transplant recipients

BACKGROUND

Skin cancer, in particular squamous cell carcinoma (SCC), is the most common malignancy after solid-organ transplantation. SCC has been reported in immunosuppressed patients receiving voriconazole, but the agent has not been shown to be a risk factor. Universal voriconazole prophylaxis and alemtuzumab induction are standard in our lung transplant program.

METHODS

We performed a retrospective, case-control study (matched 1:3) among lung transplant recipients at our center from 2003 to 2008.

RESULTS

SCC was diagnosed in 3.1% (17 of 543) of patients at a median follow-up of 36 months. Median time to development of SCC was 19 months post-transplant. Risk factors for SCC by univariate analysis included older age (p = 0.02), residence in locations with high levels of sun exposure (p = 0.0001), single-lung transplant (p = 0.02) and duration (p = 0.03) and cumulative dose (p = 0.03) of voriconazole. Duration of voriconazole (hazard ratio [HR] = 2.1; p = 0.04) and residence in locations with high sun exposure (HR = 3.8; p = 0.0004) were independent risk factors by multivariate analysis. SCC lesions were located on the head and neck in 94% of cases, and 53% had multiple lesions. All patients were treated with surgery. At least one independent lesion developed subsequently in 47% of patients. Local spread and distant metastases each occurred in 7% of cases. There were no deaths among the cases.

CONCLUSIONS

Voriconazole exposure is a risk factor for SCC after lung transplantation, particularly among older patients living in areas with high sun exposure. Voriconazole should be used cautiously in these patients.

Relationship of cytomegalovirus load assessed by real-time PCR to pp65 antigenemia in organ transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection in immunocompromised patients can lead to viremia associated with morbidity and mortality. Monitoring of viral loads in blood is critical for initiating and monitoring antiviral treatment.

OBJECTIVES

Validate quantitative real-time PCR assay targeting the US17 and UL54 regions of the CMV genome for automated DNA and extraction and amplification.

STUDY DESIGN

3422 blood specimens from organ transplant recipients, including longitudinal specimens from 12 organ transplant recipients, were tested by CMV PCR and pp65 antigenemia.

RESULTS

CMV PCR for both US17 and UL54, was more sensitive and detected CMV DNA earlier and for longer than the CMV pp65 antigenemia test. Using antigenemia results as a reference standard, an optimal cutoff of 500 normalized copies was calculated for both US17 and UL54 PCR targets based on high sensitivity, specificity, and positive and negative predictive values. CMV DNA levels tracked well with clinical symptoms, response to treatment, and antigenemia.

CONCLUSIONS

Detection of persistent increases in CMV DNA levels above 500 normalized copies by this real-time PCR assay is indicative of symptomatic CMV disease in organ transplant recipients. Quantitative real-time PCR for CMV DNA can be used in lieu of antigenemia for monitoring CMV infection and determining when to initiate preemptive treatment.

Cryptococcosis in liver and kidney transplant recipients receiving anti-thymocyte globulin or alemtuzumab

Rabbit anti-thymocyte globulin (ATG) and alemtuzumab have been used for induction or preconditioning and for the treatment of acute rejection in organ transplant recipients in many centers. Such regimens may lead to a substantial decline in the CD4 lymphocyte count to levels seen in other population groups at high risk of cryptococcosis. In view of this, we examined the impact of such therapy on the cumulative incidence of cryptococcosis among liver and kidney recipients. A total of 834 liver and 727 kidney transplants were performed during the study period. Seven hundred and eighty-one patients did not receive ATG or alemtuzumab; 646 received 1 dose of either drug, and 134 patients received 2 doses of either drug. The cumulative incidence of cryptococcosis was 0.26% (2/781) among those who did not receive ATG or alemtuzumab; 0.3% (2/646) among those who received only 1 dose, and 2.24% (3/134) among those who received 2 doses (P=0.03). There were 5 cases of cryptococcosis in liver recipients and 2 in kidney recipients. There were 3 cases of cryptococcal meningitis, 3 of pneumonia, and 1 of disseminated disease. The 2 kidney recipients had meningitis. Diagnosis occurred at a median of 255 days (range 7-517) after transplantation. The mortality rate was 14.2%. We conclude that the use of 1 dose of ATG or alemtuzumab is not associated with an increased cumulative incidence of cryptococcosis, but that those patients receiving 2 doses are at increased risk.

Successful outcome of human metapneumovirus (hMPV) pneumonia in a lung transplant recipient treated with intravenous ribavirin

Human metapneumovirus (hMPV) has recently been shown to be a prominent cause of respiratory infections in immunocompromised hosts, and is associated with high morbidity and mortality. We report a case of hMPV pneumonia in a lung transplant recipient presenting with respiratory failure and sepsis syndrome. hMPV was diagnosed by polymerase chain reaction, and treated with intravenous ribavirin with a successful outcome.

Risk factors, clinical characteristics, and outcome of Nocardia infection in organ transplant recipients: a matched case-control study

BACKGROUND

Risk factors for Nocardia infection in organ transplant recipients have not been formally assessed in the current era of transplantation.

METHODS

We performed a matched case-control study (1:2 ratio) between January 1995 and December 2005. Control subjects were matched for transplant type and timing. Univariate matched odds ratios were determined and conditional logistic regression was performed to identify independent risk factors. Clinical and microbiological characteristics of all case patients were reviewed.

RESULTS

Among 5126 organ transplant recipients, 35 (0.6%) were identified as having cases of Nocardia infection. The highest frequency was among recipients of lung transplants (18 [3.5%] of 521 patients), followed by recipients of heart (10 [2.5%] of 392), intestinal (2 [1.3%] of 155), kidney (3 [0.2%] of 1717), and liver (2 [0.1%] of 1840) transplants. In a comparison of case patients with 70 matched control subjects, receipt of high-dose steroids (odds ratio, 27; 95% confidence interval, 3.2-235; P=.003) and cytomegalovirus disease (odds ratio, 6.9; 95% confidence interval, 1.02-46; P=.047) in the preceding 6 months and a high median calcineurin inhibitor level in the preceding 30 days (odds ratio, 5.8; 95% confidence interval, 1.5-22; P=.012) were found to be independent risk factors for Nocardia infection. The majority of case patients (27 [77%] of 35) had pulmonary disease only. Seven transplant recipients (20%) had disseminated disease. Nocardia nova was the most common species (found in 17 [49%] of the patients), followed by Nocardia farcinica (9 [28%]), Nocardia asteroides (8 [23%]), and Nocardia brasiliensis (1 [3%]). Of the 35 case patients, 24 (69%) were receiving trimethoprim-sulfamethoxazole for Pneumocystis jirovecii pneumonia prophylaxis. Thirty-one case patients (89%) experienced cure of their Nocardia infection.

CONCLUSIONS

Receipt of high-dose steroids, history of cytomegalovirus disease, and high levels of calcineurin inhibitors are independent risk factors for Nocardia infection in organ transplant recipients. Our study provides insights into the epidemiology of Nocardia infection in the current era, a period in which immunosuppressive and prophylactic regimens have greatly evolved.

Opportunistic infections in 547 organ transplant recipients receiving alemtuzumab, a humanized monoclonal CD-52 antibody

BACKGROUND

Alemtuzumab is being increasingly used for the prevention and/or treatment of acute allograft rejection in organ transplant recipients. We assessed the risks of infection in, to our knowledge, the largest cohort and broadest range of organ transplant recipients yet reported to have received alemtuzumab.

METHODS

All patients who received alemtuzumab from September 2002 through March 2004, either as induction therapy at the time of transplantation or for the treatment of rejection, were evaluated for the development of an opportunistic infection (OI) until death or for 12 months after receipt of the last dose of alemtuzumab.

RESULTS

A total of 547 recipients were included, 65% of whom received alemtuzumab for induction therapy only. Overall, 56 recipients (10%) developed 62 OIs, including cytomegalovirus disease (n = 16), BK virus infection (n=12), posttransplantation lymphoproliferative disease (n=5), human herpesvirus 6 infection (n=1), parvovirus infection (n=1), esophageal candidiasis (n=12), cryptococcosis (n=2), invasive mold infection (n=4), Nocardia infection (n=4), mycobacterial infection (n=3), Balamuthia mandrillaris infection (n=1), and toxoplasmosis (n=1). Patients who received alemtuzumab for induction therapy were significantly less likely to develop an OI, compared with patients who received alemtuzumab for rejection therapy (4.5% vs. 21%; P<.001). Independent predictors of the development of an OI were administration of alemtuzumab for rejection therapy (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.8-6.8; P<.001), allograft failure (OR, 2.1; 95% CI, 1.1-4.4; P=.04), and receipt of a lung transplant (OR, 3.7; 95% CI, 1.7-8.0; P=.001) or an intestinal transplant (OR, 8.3; 95% CI, 3.5-19.5; P<.001).

CONCLUSIONS

Patients who received alemtuzumab for the treatment of allograft rejection were significantly more likely to develop an OI, compared with patients who received alemtuzumab for induction therapy only. Such data have implications for new antimicrobial prophylactic strategies.

Voriconazole prophylaxis in lung transplant recipients

Lung transplant recipients have one of the highest rates of invasive aspergillosis (IA) in solid organ transplantation. We used a single center, nonrandomized, retrospective, sequential study design to evaluate fungal infection rates in lung transplant recipients who were managed with either universal prophylaxis with voriconazole (n = 65) or targeted prophylaxis (n = 30) with itraconazole +/- inhaled amphotericin in patients at high risk (pre- or posttransplant Aspergillus colonization [except Aspergillus niger]). The rate of IA at 1 year was better in lung transplant recipients receiving voriconazole prophylaxis as compared to the cohort managed with targeted prophylaxis (1.5% vs. 23%; p = 0.001). Twenty-nine percent of cases in the targeted prophylaxis group were in patients colonized with A. niger who did not receive itraconazole. A three-fold or higher increase in liver enzymes was noted in 37-60% of patients receiving voriconazole prophylaxis as compared to 15-41% of patients in the targeted prophylaxis cohort. Fourteen percent in the voriconazole group as compared to 8% in the targeted prophylaxis group had to discontinue antifungal medications due to side effects. Voriconazole prophylaxis can be used in preventing IA in lung transplant recipients. Regular monitoring of liver enzymes and serum concentrations of calcineurin inhibitors are required to avoid hepatotoxicity and nephrotoxicity.

Variation in antifungal prophylaxis strategies in lung transplantation

We conducted a survey of 50 lung transplant centers across the world to evaluate the variation in antifungal prophylaxis practices. These 50 centers performed 63% of the world's lung transplants reported in 2001. Eighty-six percent (43/50) of the centers responded to the survey. Sixty-nine percent (30/43) of centers used universal antifungal prophylaxis. Aerosolized amphotericin B deoxycholate (AmBd) alone or in combination with itraconazole was used at 56% (24/43) of centers. The median duration of prophylaxis with aerosolized AmBd and itraconazole was 30 and 90 days, respectively. Seventy-four percent of the centers surveyed agreed to participate in future research prophylaxis protocols, which they felt should include both diagnostic and therapeutic arms. Our survey is the first documentation of the international variation in antifungal prophylactic strategies in lung transplant recipients, and underscores the need for multicenter, randomized trials of antifungal prophylaxis in lung transplant recipients.

Acinetobacter baumannii bloodstream infection while receiving tigecycline: a cautionary report

OBJECTIVES

Tigecycline has shown in vitro activity against Acinetobacter baumannii. Yet, published clinical experience with tigecycline use outside clinical trials is lacking. We describe, for the first time, bloodstream infection caused by tigecycline-non-susceptible A. baumannii occurring in patients receiving tigecycline for other indications. The possible mechanisms of resistance and pharmacokinetic limitations of the drug are addressed.

METHODS

The clinical records of involved patients were systematically reviewed. Tigecycline susceptibility testing was initially performed using the Etest method and confirmed by agar dilution. Involved isolates underwent PFGE and exposure to phenyl-arginine-beta-naphthylamide (PAbetaN), an efflux pump inhibitor.

RESULTS

Two patients developed A. baumannii bloodstream infection while receiving tigecycline. Tigecycline was administered for other indications for 9 and 16 days, respectively, before the onset of A. baumannii infection. Patient 1 died of overwhelming A. baumannii infection and Patient 2 recovered after a change in antibiotic therapy. The MICs of tigecycline were 4 and 16 mg/L, respectively. Both isolates had a multidrug-resistant phenotype and were genotypically unrelated. After exposure to PAbetaN, the MICs reduced to 1 and 4 mg/L, respectively.

CONCLUSIONS

To our knowledge, this is the first clinical description of bloodstream infection caused by tigecycline-non-susceptible A. baumannii. Such resistance appears to be at least partly attributable to an efflux pump mechanism. Given the reported low serum tigecycline levels, we urge caution when using this drug for treatment of A. baumannii bloodstream infection.

Bloodstream infections in organ transplant recipients receiving alemtuzumab: no evidence of occurrence of organisms typically associated with profound T cell depletion

BACKGROUND

Alemtuzumab is a humanized monoclonal antibody directed against CD52, a cell surface antigen expressed on B and T lymphocytes, monocytes and NK cells. Its use results in a profound decrease in CD4 positive T lymphocytes. Alemtuzumab is used as induction immunosuppression and therapy for rejection in organ transplant recipients in some centers. We followed a cohort of 449 consecutive transplant recipients who received alemtuzumab to determine the occurrence of bloodstream infections, particularly those previously associated with decrease in CD4 positive T lymphocytes.

PATIENTS AND METHODS

Fifteen percent (69/449) patients had at least one episode of bloodstream infection. However, no patient had bacteremia with Streptococcus pneumoniae, Listeria monocytogenes, non-typhoidal Salmonella or Mycobacterium avium complex. Fungaemia was rare, occurring in 1.5% of patients. The most common organisms isolated from the blood were Staphylococcus aureus (21 episodes), coagulase negative Staphylococcus (14 episodes), Klebsiella pneumoniae (12 episodes), Enterococcus faecium (11 episodes), Pseudomonas aeruginosa (10 episodes), Enterococcus faecalis (9 episodes) and Escherichia coli (7 episodes).

DISCUSSION

We conclude that although alemtuzumab use is associated with profound CD4 positive T lymphocyte depletion, alemtuzumab does not seem to be associated with an increased risk of bloodstream infection with pathogens typically seen in other disorders of CD4 cell depletion, such as acquired immunodeficiency syndrome.

Reactivation of Hepatitis B Infection following Allogeneic Bone Marrow Transplantation in a Hepatitis B-Immune Patient: Case Report and Review of the Literature

BACKGROUND

Reactivation of hepatitis B virus (HBV) infection following allogeneic bone marrow transplantation is a rare phenomenon.

METHODS

Reverse seroconversion, defined as the clearance of antibody to hepatitis B surface antigen (HBsAb) and the appearance of hepatitis B surface antigen (HBsAg) in a patient with resolved HBV infection (i.e., a HBsAg-negative, HBsAb-positive, hepatitis B core antibody-positive patient) following receipt of a bone marrow transplant is described. A review of related cases in the literature was undertaken to identify clinical features associated with this phenomenon.

RESULTS

We present a case of reactivation of HBV infection in a 47-year-old man after receipt of an allogeneic bone marrow transplant for acute myelogenous leukemia. Before undergoing bone marrow transplantation, the presence of HBsAb and hepatitis B core antibody and the absence of HBsAg indicated clearance of natural HBV infection. The donor was HBsAg and HBsAb negative. Twenty-nine months after bone marrow transplantation, the patient developed transaminitis and evidence of active HBV infection (the patient had test results positive for HBsAg, negative for HBsAb, and positive for HBV DNA). A total of 28 other cases of reverse seroconversion have been described in the literature, 11 of which provided adequate information to be summarized in detail together with the present case. Reactivation of HBV infection following bone marrow transplantation appears to occur almost exclusively in patients who have received marrow from an HBsAb-negative donor and have experienced graft-versus-host disease, the onset of which is associated with tapering of immunosuppressive therapy.

CONCLUSIONS

Although HBV reverse seroconversion is an uncommon event, understanding the clinical features associated with the development of HBV reverse seroconversion may provide insight into how such a potentially fatal complication may be avoided.

Cavitary pneumonia due to Rhodococcus equi in a heart transplant recipient

Rhodococcus equi is an uncommon human pathogen that usually affects immunocompromised patients. We present a case of a 68-year-old male heart transplant recipient, who developed rhodococcal pneumonia with secondary bacteremia 10 months post-transplant. The patient was a retired carpenter who was involved in breeding of horses. He responded completely to the treatment with vancomycin and imipenem/cilastin, followed by oral ciprofloxacin and minocycline for total treatment duration of 5 months. This case highlights the association between an animal exposure and infection with a unique opportunistic pathogen.

Exploring the pathogenesis of necrotizing fasciitis due to Streptococcus pneumoniae

Monobacterial necrotizing fasciitis is a rare form of soft tissue infection usually caused by the group A beta-hemolytic Streptococcus. Soft tissue infection is an uncommon clinical manifestation of invasive disease due to Streptococcus pneumoniae. We describe 3 cases of pneumococcal necrotizing fasciitis and explore potential pathogen-specific mechanisms of pathogenesis. The clinical characteristics of necrotizing fasciitis due to S. pneumoniae and group A beta-hemolytic Streptococcus appear to overlap. The similarities include predominant occurrence in elderly adults with underlying chronic illness, predilection for lower extremity infection, progression to toxic shock-like syndrome and a high case fatality rate. No DNA fragments corresponding to speA, speB or speC were amplified by PCR from the 3 pneumococcal isolates. Western immunoblot revealed no evidence of SpeA, SpeB or SpeC protein expression. Evaluation for protease production and cytotoxicity was unrevealing. The similar clinical presentation of pneumococcal necrotizing fasciitis to the disease caused by the group A beta-hemolytic Streptococcus has important therapeutic implications. The molecular mechanisms underlying the pathogenesis are unclear. Prospective population-based studies are required to define the epidemiology of this infection.

Effects of environmental endocrine disruptors on the sex differentiation in Korean rockfish, Sebastes schlegeli

The effects of estradiol-17beta, methyltestosterone, tributyltin, bisphenol A and 2,4-dinitrophenol on sex differentiation were investigated in the Korean rockfish, Sebastes schlegeli. The 51 day-old fry with undifferentiated gonads were fed with food containing the chemicals at 0.05, 0.5, 5, 50 and 100 micro/g diet for 29 days. Sex ratio and gonadal abnormality after the chemical treatment were determined by histological examination of gonads. In control group, the sex ratio of fry was 1:1.3 (female:male), and more males than females appeared. The sex of fry fed with estradiol-17beta at 5, 50 and 100 micro/g diet was all females. Feminization of the fry was induced by exogenic estradiol-17beta. In the methyltestosterone group, sex ratio of fry was 1:10.2 in 0.05 micro/g diet, 1:2.4 in 0.5 micro/g diet, 1:3.1 in 5 micro/g diet, 1:1.2 in 50 micro/g diet and 1:2.3 in 100 micro/g diet. Masculinization of the fry was induced by methyltestosterone at the lowest concentration. Furthermore, intersex of the fry was observed. The number of intersex fry was 23.3, 25.0 and 35.3 at 0.5, 5 and 50 micro/g diet of methyltestosterone, respectively. Sex ratio of bisphenol A group showed no difference with that of the control. The sex of fry fed with 2,4-dinitrophenol at 5, 50 and 100 micro/g diet was all females. 2,4-dinitrophenol should be considered as a new member of endocrine disruptors. In tributyltin group, the sex ratio of fry at 100 micro/g diet of tributyltin was 5.4:1. Tributyltin induced the feminization of the fry at the highest dose. Tributyltin showed an estrogenic effect in the Korean rockfish in contrast to an androgenic effect in gastropods.

De novo malignancies after liver transplantation: a major cause of late death

1. Recurrent and de novo malignancies are the second leading causes of late death in liver transplant recipients, following age-related cardiovascular complications. 2. The increased incidence of de novo malignancies in liver transplant recipients compared with the general population reflects their demographic makeup, known preexistent risk factors for cancer, greater rate of chronic viral infection, and actions of exogenous immunosuppression. 3. The greatest incidence of de novo malignancies is seen in cancers associated with chronic viral infections, such as Epstein-Barr virus-associated posttransplant lymphoproliferative disease, and skin cancers, including squamous cell carcinoma and Kaposi's sarcoma. 4. Although a greater incidence of such malignancies as oropharyngeal malignancy and colorectal cancer was noted, there did not appear to be an increased risk for liver transplant recipients matched for age, sex, and length of follow-up using modified life-table technique and Surveillance Epidemiology End Result data with a similar at-risk group. However, they may present with more advanced stages of disease. 5. An increased incidence of de novo cancers in chronically immunocompromised liver transplant recipients demands careful long-term screening protocols to help facilitate diagnosis at an earlier stage of disease.