Risk factors of severe blastomycosis and comparison of diagnosis and outcomes between immunocompetent and immunocompromised patients

BACKGROUND

Blastomycosis is an endemic fungal infection that causes pulmonary and systemic disease. It can occur irrespective of the patient's immune status. The risk factors associated with the severity of the disease are not well studied.

METHODS

This is a retrospective study of patients admitted with blastomycosis at the University of Kentucky Hospital from 2004 to 2019. Logistic regression was used to identify variables associated with severe blastomycosis.

RESULTS

A total of 76 patients were identified; 22 (28.9%) had at least one immunosuppressive condition. Pulmonary blastomycosis was reported in 49/76 (65%) of the patients and disseminated infection in 27/76 (35.5%). All diagnostic tests were not significantly different in diagnostic results in immunocompromised vs immunocompetent patients. Cultures and histopathology were positive in 56/61 (91.8%) and 54/63 (85.7%) respectively. Blastomyces or Histoplasma antigen test was positive in 13/17 (76.4%) in immunocompromised patients compared to 26/42 (61.9%) in immunocompetent patients. Immunocompromised patients were more likely to be admitted to the hospital and ICU compared to immunocompetent patients. In the multivariate analysis, pulmonary multilobar disease (RR 5.68; 95% CI 2.13-15.15), obesity (RR 2.39; 95% CI 1.26-4.51), diabetes mellitus (RR 3.50; 95% CI 1.38-8.90) and immunosuppression (RR 2.28; 95% CI 1.14-4.56) were significant independent risk factors for severe blastomycosis. Inpatient mortality proportion was higher in immunocompromised patients but not statistically significant.

CONCLUSION

Pulmonary multilobar disease, obesity, diabetes mellitus and immunosuppression were risk factors associated with severe blastomycosis. Immunocompromised patients required more frequent hospitalisations compared to immunocompetent patients.

Changing demographics and risk factors for cryptococcosis: A 12-year review at a tertiary care centre

BACKGROUND

Cryptococcosis is classically associated with the immunocompromised patients but there is a rising appreciation for its impact on the immunocompetent hosts. We sought to analyse the trends, diagnosis, treatment of different hosts and the effect of immunodeficiency and chronic liver disease on relapse and in-house mortality.

METHODS

This is a retrospective study of 12 years of patients with cryptococcosis, divided into three different groups: HIV-infected, transplant and non-HIV non-transplant (NHNT). Data were analysed with Chi-square, unpaired parametric t test, simple and multivariate logistic regression analysis.

RESULTS

Of 114 identified patients, 23 (20.2%) had HIV infection, 11 (9.6%) had transplant, 80 (70.2%) were NHNT patients. Overall, mortality was 28.1% (32/114) and relapse occurred in 10.5% (12/114) of patients. The mortality trend was higher (OR = 2.346, p = .287) in the transplant group (45.5%, 5/11) than in HIV (26.1%, 6/23) and NHNT groups (26.3%, 21/80). HIV was associated with relapse; 30.4% (7/23) for HIV-positive patients and 5.5% (5/91) for HIV-negative patients (OR = 7.525, p = .002). Chronic liver disease had a large and statistically significant association with mortality on multivariate analysis (OR = 3.583, p = .013) which was more pronounced than the HIV or transplant groups. It was independently associated with mortality by chi-square analysis (OR 3.137, p = .012).

CONCLUSION

Chronic liver disease represented 30.7% (35/114) of all studied patients. It was a risk factor for in-hospital mortality. HIV infection and transplant were not statistically significant for mortality. Relapse was highest in the HIV-infected patients at 30.4% (7/23). These data highlight the effect of type and degree of immunocompromise on cryptococcosis.

1156. Clinical and epidemiological features and outcomes of Blastomycosis in a tertiary hospital in Kentucky

Background

Blastomycosis is an endemic dimorphic fungal infection caused by Blastomyces dermatitidis. The risk factors associated with severe presentation are not well defined.

Methods

Retrospective study of patients treated for blastomycosis at the University of Kentucky Hospital from 2004-2019. Statistical analyses were performed with STATA version 12.0 (College Station, Texas). Logistic regression was used to identify variables associated with severe infections.

Results

Among 82 patients, median age was 48 years old (range: 16 - 89); 66 (80.5%) were male and 71 (92.2%) were white, 25/77 (32.4%) were obese, 24 (29.2%) were diabetic, 21 (25.6%) had COPD, 26 (31.7%) had at least one immunosuppressive condition. The median duration of illness was 86 (3-365) days. 37 (45.1%) had cough and 35 (42.6%) had dyspnea 19 (23.1%) patients were treated in the ICU, 42 (51.3%) in non-ICU inpatient wards, and 21 (25.6%) in an outpatient setting. Cultures were obtained in 69 cases, 59 (85.5%) reported as positive, KOH stain positive in 30/61 (49.1%). Histopathology was positive in 48/66 (72.7%) samples. Urine Histoplasma or Blastomyces antigen was positive in 41/58 (70.6%), and Serum Histoplasma or Blastomyces antigen was positive in 22/34 (64.7%). Among 64 (78.0%) patients with pulmonary blastomycosis, acute and chronic pneumonia were 16 (25.0%) and 12 (18.7%) cases respectively, and nodular lung lesions were reported in 36 (56.2%). Initial antifungal treatment was amphotericin B liposomal in 38/80 (47.5%), overall mortality was 11 (13.4%). A multivariable analysis was performed to find predictors of severe blastomycosis infection, no association was seen with factors as male sex (IRR 1.96; 95%CI 0.84 – 4.55), and was confirmed that significant independent associated risk factors for severe infection were age older than 50 (IRR 3.5; 95%CI 1.42-8.83), obesity (IRR 3.1; 95% CI 1.41-6.87), diabetes (IRR 2.5; 95% CI 1.16-5.50), leukocytosis (IRR 1.03; 95%CI 1.00-1.07) and anemia (IRR 3.0; 95% CI 1.55-5.85).

Conclusion

Pulmonary Blastomycosis is the most common presentation. Culture and histopathology are more sensitive than antigen assay. Independent factors associated to severe disease were older age, obesity, diabetes, and anemia at admission.

Disclosures

All Authors: No reported disclosures

653. Comparison of Yeasts identification by Biofire, Culture and ePlex for Quality Assurance purpose

Background

At the University of Kentucky Medical center (UKMC), positive fungal blood cultures are concurrently run through the Biofire Blood Culture Identification (BCID) panel which detects 5 Candida species. The newer platform, the GenMarkDx ePlex BCID-FP (fungal panel) is designed to detect 16 fungal targets. Our study compares the performance of the Biofire BCID panel’s with culture as the gold standard method. We examine the percentage of agreement by both testing methods and predict the performance of the GenMarkDx ePlex BCID-FP panel based on culture results. We also look at the number of other yeasts not included in Biofire BCID panel that could be picked up by the GenMarkDx ePlex BCID-FP panel.

Methods

Positive fungal blood cultures from July 1, 2018 to June 30, 2019 were run through the Biofire BCID panel. Culture results were used to extrapolate whether the GenMarkDx ePlex FP would provide any additional diagnostic benefit. Results were categorized as true or false positives and negatives as compared to culture as the gold standard.

Results

A total of 141 blood cultures were tested via the Biofire BCID panel for the identification of yeasts. Of these, 123 (87%) yielded Biofire results in concordance with culture results. We would expect these also to be positive on the GenMarkDx ePlex BCID-FP panel. In addition, 18 specimens (13%) would have tested positive on the GenMarkDx ePlex BCID-FP panel and not the Biofire BCID panel. These organisms were noted to be Candida lusitaniae (n=6), Cryptococcus neoformans (n=3), Candida dublinensis (n=2), and Candida keyfr (n=1). Organisms that were found on culture that were not detected by both GenMarkDx ePlex BCID-FP panel and Biofire BCID panel were Candida nivariensis (n=2), Pichia ohmeri (n=1), Trichospon species (n=2).

Conclusion

Based on these data, we expect that the ePlex would have correctly identified 95.9% of the yeasts in this patient population. This represents an additional 18 (13%) of specimens that could be detected rapidly from the positive blood culture if the GenMarkDx ePlex BCID-FP panel were used instead of the Biofire BCID panel. Early identification can influence the choice of antifungal agent. Less than 5 % of the yeasts would have remained unidentified by ePLex compared to 13% for Biofire.

Disclosures

All Authors: No reported disclosures

1713. Impact of False-Positive Low-Titer Cryptococcal Antigen Testing

Background

At University of Kentucky (UK) HealthCare, the transition from latex agglutination testing (Remel, Lenexa, KS) to IMMY Cryptococcal Antigen Lateral Flow Assay (CrAg LFA) occurred in September 2016. A few months later, it was noticed that several cryptococcal cases were diagnosed with weak positive test results where the diagnosis could not be confirmed by additional testing. The purpose of this study was to analyze the characteristics of these patients, and to assess the interventions they received based on positive results.

Methods

This was a retrospective study of the patients with positive CrAg LFA treated at UK HealthCare from November to December 2016. Low antigen titers (≤ 1:20) were considered to be false positive if repeat testing with the Remel Cryptococcal Latex assay, IMMY latex and IMMY microwell EIA were negative, cultures and histopathology were negative and there was no clear clinical evidence of infection.

Results

During this 2-month period, CrAg LFA was positive in 12 patients. The diagnosis of cryptococcosis could not be confirmed by additional testing in 9 (75%) individuals. Cirrhosis/liver disease was present in 3 (33.3%) patients, 5 (55.6%) underwent lumber puncture and antifungal therapy was administered in 8 (88.9%) patients (Table 1). CrAg LFA was false positive in 1/2 (50%) HIV, 3/3 (100%) transplant, and 5/7 (71.4%) non-HIV/non-transplant patients (Figure 1). Among the false positives, 4 (44.4%) patients had titer of 1:5, two (22.2%) had 1:20, and the original positive screen was not detected upon titration in 3 (33.3%) other patients. One HIV patient received a complete treatment course for unconfirmed cryptococcal meningitis because an LP could not be performed.

Conclusion

False-positive low CrAg LFA titers led to unnecessary tests, antifungal treatments and prolonged hospitalization in some patients. One-third of these individuals had cirrhosis/liver disease. Other institutions also reported false-positive low CrAg LFA titers. As a result, the company staged a recall of the specific lot and corrected the problem in reagent manufacturing. Low-positive titers using CrAg LFA should be interpreted carefully and further testing should be considered as determined by the clinical situation.

Disclosures

All authors: No reported disclosures.

1982. A Diagnostic Stewardship Intervention for Clostridioides difficile: Impact of Stool Toxin Testing on Treatment of Adult Inpatients

Background

Testing for Clostridioides difficile infection has been the subject of recent debate. Guidelines from the Infectious Diseases Society of America now support the addition of a stool toxin test to a positive nucleic acid amplification test (NAAT) as part of a multi-step testing algorithm. In November 2017, the University of Kentucky HealthCare system added stool toxin testing to any specimen positive for C. difficile by NAAT. This change was accompanied by face to face education with provider groups and clinical decision support in the form of interpretive verbiage added to the results that are reported into the electronic record. The objective of this study was to assess whether this diagnostic stewardship intervention made an impact on C. difficile treatment

Methods

We performed a retrospective review of adult patients admitted to UK HealthCare from November 1, 2017 through October 31, 2018 who tested positive by NAAT but negative by stool toxin test to determine whether or not they were treated. We also assessed treatment by service line to see whether there were treatment differences among these groups. A cost analysis was also performed.

Results

A total of 300 adult inpatients were positive for C. difficile by NAAT during the study period with 71% (213 patients) having a negative stool toxin test. Of those, 58% (123) were never started on C. difficile therapy and an additional 14% (30) had their therapy stopped after 48 hours. Only 28% (60) of these patients received a full course of therapy. Hospital medicine had the highest rate of non-treatment at 82%. Conversely, our solid-organ and bone marrow transplant services had the lowest rate of non-treatment at 31%. Overall, this approach was associated with an estimated 1470 oral vancomycin days avoided (5,880 doses) and a cost savings of $6,278.

Conclusion

The addition of stool toxin testing to NAAT combined with education and clinical decision support lead to a dramatic reduction of treatment for NAAT positive but toxin-negative patients. This form of diagnostic stewardship had a significant impact on therapy decisions and can be a powerful antimicrobial stewardship approach to decrease unnecessary treatment of C. difficile colonization.

Disclosures

All authors: No reported disclosures.

1705. Clinical Characteristics and Outcomes of Cryptococcosis in a Tertiary Care Center in Kentucky, 2005 to 2017

Background

Cryptococcosis is an invasive fungal infection that causes pneumonia and extrapulmonary infection. This study explores its presentations, diagnostic tests, and outcome in different groups over a 12-year period at an academic medical center.

Methods

This was a retrospective study of the patients treated at University of Kentucky HealthCare from October 16, 2005 to October 15, 2017. Inclusion criteria were positive cryptococcal antigen (Ag), positive culture, or presence of yeast morphologically consistent with Cryptococcus on cyto- or histopathology. Patients were divided into HIV-infected, solid-organ transplant (SOT) recipients, and non-HIV/non-transplant groups. Cryptococcal meningitis comprised of either positive CSF Ag, culture, cytology or histopathology.

Results

A total of 114 patients were identified; 23 HIV-infected, 11 SOT recipients and 80 non-HIV/non-transplant patients (Table 1). Cryptococcus neoformans was the most common yeast isolated (91.8%). Cryptococcal meningitis was seen in 56% of total patients whereas 27% had isolated cryptococcal pneumonia (P < 0.01). Blood cultures and serum Ag were positive in 34% and 70%, respectively. Only 8.7% of HIV-infected patients had isolated pulmonary cryptococcosis compared with 36.4% in SOT recipients (P < 0.01). In patients with cryptococcal meningitis, abnormal CSF cell count, protein, or glucose was noted in 85.3%; India ink was positive in 61.3% and CSF culture was positive in 73.4% (Table 2, Figure 1). CSF cryptococcal Ag was detected in 95.6% cases if CSF cultures were positive, whereas serum Ag was positive in only 85.1% of meningitis cases. Mortality was seen in 48.6% (17/35) of patients with cirrhosis/liver disease, compared with 21.5% (17/79) of non-cirrhosis/liver disease (P = 0.003). Transplant group had 54.5% mortality compared with 26.1% in HIV group (P = 0.016).

Conclusion

Cryptococcal meningitis was the most common presentation for cryptococcal disease in all three groups. Isolated pulmonary disease was least common in the HIV-infected group. Inpatient mortality rate was higher in patients with cirrhosis/liver disease and transplant group compared with those without cirrhosis/liver disease and HIV group, respectively. It is imperative to rule out meningitis in immunosuppressed patients with cryptococcal pneumonia.

Disclosures

All authors: No reported disclosures.

529. Overdiagnosis of Clostridioides difficile with a Multiplex PCR Panel

Background

While advantageous by casting a wider diagnostic net, multiplex panels can be problematic if the pretest probability is low. A significant increase in reported Clostridioides difficile infections (CDI) was noted at our institution following introduction of a multiplex comprehensive GI (CGI) panel which includes an analyte for C. difficile. Owing to these concerns, the C. difficile analyte result was suppressed when reporting and providers were advised to order a standalone C. difficile PCR (CDPCR) test if CDI was a concern. The objective of this study was to investigate concerns of false positive C. difficile results from the CGI panel.

Methods

C. difficile diagnostic practices were prospectively evaluated from April to August 2017. Patient charts were reviewed in response to a positive C. difficile analyte on the CGI panel. CDPCR results were reviewed if ordered. If not ordered, chart review and discussion with the provider was conducted to investigate clinical suspicion for CDI. The results were analyzed to examine the performance of the C. difficile analyte on the CGI panel.

Results

Overall, a total of 1,611 CGI panels were performed with C. difficile being detected in 156 specimens. Of these positive results, a subanalysis was performed on 123 positive specimens for whom complete data was available. A CDPCR was performed in 80 (65%) of these specimens. Among those, only 44 (55%) were CDPCR positive and 22 (28%) were CDPCR negative (likely a false-positive CGI result), and 14 (17%) were rejected because of specimen consistency. For the remaining 43 C. difficile-positive CGI panel specimens that did not have an accompanying CDPCR, seven were in children below 2 years of age. Direct provider discussion occurred in the remaining 36 cases. Providers declined CDPCR testing in 24 of those cases due to a lack of clinical concern.

Conclusion

The use of the CGI panel for C. difficile led to over diagnosis of CDI. This could have significant consequences for clinical care and the reporting of hospital acquired infections.

Disclosures

All authors: No reported disclosures.

Mycobacterium marinum Infection After Exposure to Coal Mine Water

Mycobacterium marinum infection has been historically associated with exposure to aquariums, swimming pools, fish, or other marine fauna. We present a case of M marinum left wrist tenosynovitis and elbow bursitis associated with a puncture injury and exposure to coal mine water in Illinois.

Post operative fungal endopthalmitis due to Geotrichum candidum

Geotrichum species have been rarely reported as the cause of sepsis, disseminated infection in immunosuppressed patients. The patient we describe developed indolent endophthalmitis four months after her routine right eye cataract surgery. The intraoperative sample from right vitreous fluid grew Geotrichum candidum. The patient underwent vitrectomy, artificial lens explantation and intravitreal injection of amphotericin B followed by oral voriconazole. Despite these interventions, she underwent enucleation. This is the first published case of Geotrichum candidum endophthalmitis.

Temporal trends, clinical characteristics, and outcomes of histoplasmosis in a tertiary care center in Kentucky, 2000 to 2009

The impact of highly active antiretroviral therapy (HAART) on the epidemiology of AIDS-associated histoplasmosis in the past decade is poorly defined. Among 100 patients with histoplasmosis in an endemic region between 2000 and 2009, 42 patients were immunocompetent, 32 were infected with HIV, and 26 were non-HIV-immunocompromised patients. The percentage with HIV decreased 67% in 2000-2001 to 18% in 2008-2009 (P = .004), while the proportion of non-HIV immunocompromised patients increased, 8% to 41% (P = .14). Histoplasma antigen was the most sensitive test (73%), whereas potassium hydroxide examination of clinical specimens was the least sensitive test (33%) in all 3 groups. Bronchoalveloar fluid culture (74%) had the highest yield among the cultures. The relapse rate was higher in HIV-infected patients compared to the other 2 groups (P = .04). The epidemiology of histoplasmosis in our endemic area has changed during the era of HAART. Organ transplantation and increasing use of immunosuppressive agents for chronic inflammatory conditions in non-HIV patients now account for most of the cases of histoplasmosis.

Invasive enteric infections in hospitalized patients with underlying strongyloidiasis

Disseminated strongyloidiasis is often associated with enteric bacterial infections. This study was undertaken to determine if enteric organisms caused extraintestinal infections in patients infected with Strongyloides stercoralis but without apparent dissemination. The medical records of hospitalized patients from central Kentucky with strongyloidiasis (1993-2003) were examined to determine the occurrence of extraintestinal infections with enteric organisms. Of 30 patients with S stercoralis, 16 had invasive infections, including sepsis, meningitis, pneumonia, peritonitis, and endocarditis caused by enteric bacteria and Candida organisms. Infections were seen in 8 (62%) of 13 patients with disseminated strongyloidiasis and 8 (47%) of 17 with disease apparently limited to the gastrointestinal tract. Fifteen patients were receiving corticosteroids or other immunosuppressive therapy. Peripheral eosinophilia was seen in only 23% (7/30). Infection with S stercoralis, even without obvious dissemination, may predispose to invasive infections caused by enteric organisms. In Strongyloides-endemic areas, patients with invasive infections caused by enteric organisms should be examined for coinfection with S stercoralis.

Pseudallescheriasis: a summary of patients from 1980-2003 in a tertiary care center

CONTEXT

Pseudallescheria boydii is being increasingly isolated in immunocompromised patients.

OBJECTIVE

To present 24 years of data on patients from whom P. boydii was isolated.

DESIGN

Retrospective review of archival laboratory data and patient charts at a tertiary care hospital with a full service mycology laboratory. All patients evaluated from whom P. boydii was isolated between 1980 and 2003 were included in this study.

RESULTS

Twenty-four patients from whom P. boydii had been isolated were identified. The majority of cases represented pulmonary involvement, particularly in cystic fibrosis patients. Three additional patients had infections in surgical or traumatic lesions of the head and 4 had disseminated disease. Invasive disease was associated with underlying malignancy or transplantation and resulted in death secondary to the fungal infection in the majority of cases.

CONCLUSIONS

Pseudallescheria boydii may cause significant disease in humans. Invasive infections with P. boydii are often misdiagnosed and inadequately treated. Aggressive treatment of locally invasive disease may be of value in preventing rapid and fatal dissemination with this organism.

Zygomycosis (mucormycosis): emerging clinical importance and new treatments

PURPOSE OF REVIEW

New importance has been given to zygomycosis, as what was uncommon is no longer. Zygomycosis (mucormycosis) typically occurs in patients with leukemia, with solid-organ transplants or bone marrow transplants, with diabetic ketoacidosis, in those who have received steroids or are neutropenic, and after desferioxamine therapy. Often, both diagnostic and therapeutic measures are performed too late and are inadequate. Mortality rates may be as high as 80% in infected transplant recipients. Zygomycosis also appears to have made a subtle increase in incidence: up to 8% in autopsied patients with leukemia, and 2% in allogenic bone marrow transplant patients. Most infections are acquired by inhalation, ingestion, or trauma. They rapidly infarct blood vessels, resulting in necrosis of surrounding tissue. Over the past few years, new diagnostic procedures, susceptibility tests, and drugs have entered the clinic, and these advances are discussed in the review.

RECENT FINDINGS

With the rise in number of cases of 'zygomycosis', new scrutiny has been directed at the terms 'zygomycosis' and 'mucormycosis'. This review explains their differences and the attending relevance for the clinician. Diagnostic methods include new molecular detection assays and new susceptibility testing options. New treatment options will soon exist with triazole antifungal agents. The first one expected to enter clinical practice is posaconazole in 2005. Its metabolism, pharmacokinetics, in-vitro and in-vivo activity, and clinical study results are described. Finally, we present our approach to zygomycosis.

SUMMARY

This review discusses key elements to laboratory diagnostic and susceptibility procedures and new treatment options.

Point prevalence of Cryptosporidium, Cyclospora, and Isospora infections in patients being evaluated for diarrhea

From March to September 2001, 315 specimens from "nonrepeat" patients that were submitted for ova and parasite examination were stained using the Kinyoun modified acid-fast stain to detect the intestinal coccidians. Four patients (1.3%) were infected with coccidians, 2 with Cryptosporidium parvum and 2 with Cyclospora cayetanensis. No infections with Isospora belli were detected. In comparison, 15 patients (4.8%) had infections with one or more intestinal parasites detected by routine trichrome staining: 5 had Giardia lamblia; 2, Dientamoeba fragilis; 3, Strongyloides stercoralis; 1, Iodamoeba bütschlii; 3, Endolimax nana; 6, Blastocystis hominis; and 1, Entamoeba coli. Four patients were multiply infected. Coccidians made up 29% of the clinically significant parasitic infections. The coccidians were missed in all 4 cases because no special staining was ordered. Clinicians need to be reminded that additional tests should be ordered to fully evaluate patients with chronic diarrhea in which no diagnosis is found by routine testing.

Evaluation of methods to increase the sensitivity and timeliness of detection of Streptococcus agalactiae in pregnant women

Direct culture of rectovaginal specimens on Granada agar was compared to culture on sheep blood agar plate (SBAP) and AccuProbe detection of group B streptococcus from overnight LIM broth enhancement cultures (LIM-SBAP). Both broth-enhanced methods demonstrated excellent sensitivity (97.5% for LIM-SBAP and 93.5% for AccuProbe), while Granada agar demonstrated a sensitivity of only 40.3%.

Performance characteristics of VIDAS and directigen respiratory syncytial virus (RSV) antigen detection assays and culture for the identification of RSV in respiratory specimens

In a comparison of the Directigen and VIDAS respiratory syncytial virus antigen detection assays with viral culture, the sensitivity, specificity, positive and negative predictive values, and testing efficiency were 86, 93.1, 82.7, 94.6, and 91.2% for Directigen; 96.1, 90.8, 80.3, 98.3, and 92.3% for VIDAS; and 88.2, 100, 100, 95.7, and 96.8% for viral culture, respectively.

A decade of antimicrobial susceptibilities at the University of Kentucky Hospital

OBJECTIVE

To determine the antimicrobial susceptibility rates for key antimicrobial agents and selective bacterial pathogens in the decade of the 1990s.

METHODS

Data from 1990 to 2000 from the University of Kentucky Clinical Microbiology Laboratory were analyzed by linear regression analysis to identify agents and pathogens that show a decline in susceptibility. For selected pathogens and antimicrobial agents, predictions were made for further declines in susceptibility for 2005 and 2010.

RESULTS

Significant declines in susceptibility to selected antimicrobial agents were found for Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter cloacae, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pneumoniae. Further declines were predicted for 2005 and 2010.

CONCLUSIONS

Examination of susceptibility rates over time in a university hospital medical center provides useful data for future planning. In our institution, antimicrobial susceptibility rates have significantly declined during the 1990s for certain antimicrobial agents and bacterial pathogens. We are attempting to change our antimicrobial use patterns through formulary manipulation and clinician education, which may retard or prevent such declines in the future.

Comparative performance of herpes simplex virus type 1-specific serologic assays from MRL and Meridian Diagnostics

Two companies, MRL and Meridian Diagnostics, have developed Food and Drug Administration-approved herpes simplex virus type 1 type-specific enzyme immunoassays. The sensitivity, specificity, and overall testing efficiency of these assays were 98.2, 93.8, and 96.6% for MRL and 98.8, 99.0, and 98.1% for Meridian, making both of these kits suitable for use in the clinical lab.

Mycobacterium mucogenicum isolated from a patient with granulomatous hepatitis

Mycobacterium mucogenicum is a recently characterized, rapid-growing mycobacteria rarely seen in human infections. We describe the case of a 51-year-old man with rapidly progressive granulomatous hepatitis caused by M. mucogenicum. Although premortem evaluation failed to identify an etiologic agent, autopsy liver cultures produced smooth, rapid-growing mycobacterial colonies. Biochemical, growth, and cell wall fatty acid characteristics were consistent with the identification of M. mucogenicum.

Comparative performance of herpes simplex virus type 2-specific serologic assays from Meridian Diagnostics and MRL diagnostics

MRL Diagnostics and Meridian Diagnostics have recently designed herpes simplex virus type 2 (HSV-2)-specific enzyme immunoassays for HSV-2 antibody detection. Blood donor sera were assayed for HSV-2 antibodies by both methods. The sensitivity, specificity, and efficiency were 97.9, 95.4, and 95.9% for the MRL assay and 83.2, 98.2, and 95.5% for the Meridian assay, respectively.

Six-year study of the incidence of herpes in genital and nongenital cultures in a central Kentucky medical center patient population

Herpes infections are among the most common sexually transmitted diseases and are the most common cause of genital ulcer disease in the United States. This study addresses the changing distribution of herpes simplex virus type 1 (HSV-1) and HSV-2 in patients presenting for evaluation of herpetic infections. Viral culture results from the University of Kentucky Clinical Microbiology Laboratory were reviewed for a 6-year period (1994 through 1999). Data were collected on patient sex, site of culture, and culture result. These data were analyzed statistically to identify yearly trends. Of the 4,498 cultures analyzed, nearly equal proportions of HSV-1 (13.3%) and HSV-2 (12.0%) were detected for an overall culture positivity rate of 25.3%. Approximately two-thirds of all positive cultures were from women. Although HSV-2 remained the predominant type of genital herpes, over the 6-year span of this study, there was a trend toward increasing proportions of HSV-1 genitalis, with 31.8% of male patients and 44.8% of female patients demonstrating HSV-1 genitalis by 1999. The majority of patients with HSV in nongenital sites grew HSV-1. Although there was significant yearly variation, HSV-2 was isolated from only 9.4% of patients with nongenital HSV for the entire 6-year period. This study therefore concludes that HSV-2 remains primarily a genital pathogen, while HSV-1 is taking on an increasingly important role in causing genital ulcer disease in addition to being the primary nongenital HSV.

Zygomycetes in human disease

The Zygomycetes represent relatively uncommon isolates in the clinical laboratory, reflecting either environmental contaminants or, less commonly, a clinical disease called zygomycosis. There are two orders of Zygomycetes containing organisms that cause human disease, the Mucorales and the Entomophthorales. The majority of human illness is caused by the Mucorales. While disease is most commonly linked to Rhizopus spp., other organisms are also associated with human infection, including Mucor, Rhizomucor, Absidia, Apophysomyces, Saksenaea, Cunninghamella, Cokeromyces, and Syncephalastrum spp. Although Mortierella spp. do cause disease in animals, there is no longer sufficient evidence to suggest that they are true human pathogens. The spores from these molds are transmitted by inhalation, via a variety of percutaneous routes, or by ingestion of spores. Human zygomycosis caused by the Mucorales generally occurs in immunocompromised hosts as opportunistic infections. Host risk factors include diabetes mellitus, neutropenia, sustained immunosuppressive therapy, chronic prednisone use, iron chelation therapy, broad-spectrum antibiotic use, severe malnutrition, and primary breakdown in the integrity of the cutaneous barrier such as trauma, surgical wounds, needle sticks, or burns. Zygomycosis occurs only rarely in immunocompetent hosts. The disease manifestations reflect the mode of transmission, with rhinocerebral and pulmonary diseases being the most common manifestations. Cutaneous, gastrointestinal, and allergic diseases are also seen. The Mucorales are associated with angioinvasive disease, often leading to thrombosis, infarction of involved tissues, and tissue destruction mediated by a number of fungal proteases, lipases, and mycotoxins. If the diagnosis is not made early, dissemination often occurs. Therapy, if it is to be effective, must be started early and requires combinations of antifungal drugs, surgical intervention, and reversal of the underlying risk factors. The Entomophthorales are closely related to the Mucorales on the basis of sexual growth by production of zygospores and by the production of coenocytic hyphae. Despite these similarities, the Entomophthorales and Mucorales have dramatically different gross morphologies, asexual reproductive characteristics, and disease manifestations. In comparison to the floccose aerial mycelium of the Mucorales, the Entomophthorales produce a compact, glabrous mycelium. The asexually produced spores of the Entomophthorales may be passively released or actively expelled into the environment. Human disease with these organisms occurs predominantly in tropical regions, with transmission occurring by implantation of spores via minor trauma such as insect bites or by inhalation of spores into the sinuses. Conidiobolus typically infects mucocutaneous sites to produce sinusitis disease, while Basidiobolus infections occur as subcutaneous mycosis of the trunk and extremities. The Entomophthorales are true pathogens, infecting primarily immunocompetent hosts. They generally do not invade blood vessels and rarely disseminate. Occasional cases of disseminated and angioinvasive disease have recently been described, primarily in immunocompromised patients, suggesting a possible emerging role for this organism as an opportunist.

PCR detection of Pneumocystis carinii in bronchoalveolar lavage specimens: analysis of sensitivity and specificity

Although PCR detection of Pneumocystis carinii DNA has been described, little is known about the sensitivity or specificity of the assay in routine laboratory practice. We had the unique opportunity to use a bronchoalveolar lavage (BAL) specimen bank with samples for which the direct examination results for P. carinii were known. DNA purified from 129 selected specimens was amplified by using the primers described previously (A. E. Wakefield, F. J. Pixley, S. Banerji, K. Sinclair, R. F. Miller, E. R. Moton, and J. M. Hopkin, Mol. Biochem. Parasitol. 43:69-76, 1990). Of the 129 specimens, 37 were positive for P. carinii by direct examination. All 37 specimens were positive for P. carinii by PCR, yielding a 100% sensitivity and 100% negative predictive value for the assay. An additional 23 specimens were repeatedly positive for P. carinii by PCR but were not positive by direct examination. Review of the patient charts for these specimens with discordant results demonstrated that five of the patients were actually positive for P. carinii, as determined by either biopsy or examination of repeat or prior BAL specimens. A response to empiric therapy for P. carinii pneumonia was seen in an additional two patients. Of the remaining specimens, 8 produced no significant isolates other than P. carinii, while 12 contained culture-confirmed significant respiratory pathogens in addition to P. carinii (two fungal, nine bacterial, and one viral pathogen). Cytomegalovirus, which was of unknown significance, was isolated from 16 additional specimens. Overall, the specificity of the PCR assay was 79.3% compared to the results of direct examination. We hypothesized that the apparently poor specificity of the PCR assay was due to the increased sensitivity of the assay compared to that of direct examination. The sensitivity of the PCR assay was therefore assessed with BAL specimens containing P. carinii cysts. Serial dilutions of this preparation were evaluated by direct examination and PCR. PCR was found to be 100-fold more sensitive than direct examination, which detected one to two cysts per amplification. No false-positive results were detected in controls containing no DNA or by using target DNA from various fungal, viral, or bacterial respiratory pathogens. We conclude that PCR detection of P. carinii in BAL specimens is very sensitive and should be considered for patients whose specimens do not yield a diagnosis. The increased sensitivity of the PCR assay may help to identify those patients with low-titer infections who might benefit from directed antibiotic therapy for P. carinii and would otherwise be missed by direct examination alone.

Effects of ionic and nonionic radiographic contrast agents on endothelial cells in vitro

Intravenous administration of radiographic contrast agents results in the occasional occurrence of thrombotic complications, which are more common after the use of ionic agents than nonionic agents. To investigate the pathophysiologic basis of this thrombotic tendency, we compared the effects of ionic and nonionic contrast agents on endothelial cells in vitro. Exposure of cultured human umbilical vein endothelial cells to ionic contrast medium for 10 minutes resulted in lifting of 76% +/- 8% of cells, significantly greater than that after exposure to nonionic medium (6% +/- 4%; p less than 0.005). A modified Baumgartner chamber was used to evaluate the effects of contrast agents on adhesion of platelets in anticoagulated whole blood to everted segments of fresh or stored deendothelialized rabbit aorta segments. Exposure of fresh vessels to ionic contrast medium led to a significant increase in platelet adhesion (31% +/- 7%; p less than .01), whereas the increase was smaller after exposure to nonionic contrast medium (25% +/- 3%). Platelet adhesion to stored vessels (41% +/- 4%) was significantly greater than adhesion to fresh aorta segments (15% +/- 2%; p less than 0.001), and contrast agents did not further increase adhesion. Microscopic examination of perfused aorta segments exposed to ionic contrast medium showed platelet adherence to intact endothelial cells, a phenomenon that did not occur without prior exposure of fresh aorta segments to ionic contrast medium. These findings demonstrate that exposure of endothelial cells to ionic contrast medium results in marked changes in cell viability and adhesive properties that may contribute to their thrombotic potential.

Multimer size dependence of von Willebrand factor binding to crosslinked or noncrosslinked fibrin

von Willebrand factor (vWF) is synthesized in endothelial cells (EC) and may be either secreted constitutively or stored in Weibel-Palade bodies (WPB) for regulated release. Because fibrin stimulates rapid vWF release from EC, we examined the binding of EC synthesized vWF to fibrin. Culture medium containing constitutively secreted vWF was removed from metabolically labeled primary cultures of human umbilical vein EC, and vWF released from WPB was obtained after stimulation by A23187. vWF-deficient fibrinogen with or without factor XIII was added to releasate or media and clotted with thrombin to form crosslinked or noncrosslinked fibrin. vWF was immunopurified from releasate or media before and after clotting, and the amount and multimeric pattern of vWF bound was determined after sodium dodecyl sulfate agarose gel electrophoresis. High molecular weight multimers of vWF, whether secreted constitutively or released from WPB, bound preferentially to fibrin. Multimers of greater than 20 subunits represented 60% +/- 4% (SEM) of A23187 released vWF and 11% +/- 5% of media vWF, but binding to fibrin was similar, 96% +/- 1% and 94% +/- 2%, respectively. A progressively smaller proportion of vWF bound as multimer size decreased, and dimeric vWF binding was least, with 34% +/- 5% binding from A23187 releasate and 51% +/- 4% from media. The amount of vWF binding to crosslinked or noncrosslinked fibrin was similar, and preferential binding of high molecular weight multimers occurred with both. As measured by enzyme-linked immunosorbent assay, 45% +/- 2% of constitutively secreted vWF bound to crosslinked fibrin and 50% +/- 2% to noncrosslinked fibrin. The propolypeptide of vWF did not bind to fibrin. These findings indicate that binding of EC secreted vWF binding to fibrin depends on multimeric size but not on factor XIII crosslinking. This suggests that vWF released from EC in the presence of fibrin will bind locally, thereby facilitating platelet adhesion to the hemostatic plug or thrombus.

Mediation of fibrin-induced release of von Willebrand factor from cultured endothelial cells by the fibrin beta chain

The exposure of endothelial cells (EC) to fibrin has been shown to stimulate the rapid release of von Willebrand factor (vWf) from storage sites in Weibel-Palade bodies. We have now investigated the fibrin structural features required for stimulation of release. The role of fibrinopeptide cleavage was examined by preparing fibrin with thrombin to remove both fibrinopeptide A (FPA) and fibrinopeptide B (FPB) and with reptilase or Agkistrodon contortrix procoagulant to selectively remove FPA or FPB, respectively. vWf release was found to require FPB cleavage, whereas removal of FPA and Factor XIIIa cross-linking of fibrin were without effect. The dependence of release on FPB cleavage suggested that a site involving the NH2 terminus of the beta chain could mediate vWf secretion. To test this hypothesis, B beta chain derivatives were prepared and examined for their capacity to induce release. Purified B beta chain had no effect on release at a concentration of 20 nM but stimulated release from 26 +/- 6% of cells at 200 nM, the maximum solubility. However, after thrombin cleavage of FPB, release occurred from 36 +/- 9% of cells at 20 nM and from 60 +/- 7% at 200 nM, both significantly greater than before cleavage. FPB and B beta 1-42 showed no activity, whereas beta 15-42, representing the NH2 terminus of the thrombin cleaved beta chain, stimulated significant release at concentrations of 0.1 and 1 mM. We conclude that FPB cleavage from fibrin is required for stimulation of vWf release from EC and that this is mediated by a site that includes the NH2 terminus of the beta chain.

Fibrin induces release of von Willebrand factor from endothelial cells

Addition of fibrinogen to human umbilical vein endothelial cells in culture resulted in release of von Willebrand factor (vWf) from Weibel-Palade bodies that was temporally related to formation of fibrin in the medium. Whereas no release occurred before gelation, the formation of fibrin was associated with disappearance of Weibel-Palade bodies and development of extracellular patches of immunofluorescence typical of vWf release. Release also occurred within 10 min of exposure to preformed fibrin but did not occur after exposure to washed red cells, clot liquor, or structurally different fibrin prepared with reptilase. Metabolically labeled vWf was immunopurified from the medium after release by fibrin and shown to consist of highly processed protein lacking pro-vWf subunits. The contribution of residual thrombin to release stimulated by fibrin was minimized by preparing fibrin clots with nonstimulatory concentrations of thrombin and by inhibiting residual thrombin with hirudin or heating. We conclude that fibrin formed at sites of vessel injury may function as a physiologic secretagogue for endothelial cells causing rapid release of stored vWf.

Effects of streptozotocin-induced diabetes and insulin on phospholipid content of R3230AC mammary tumor cells

The influence of diabetes and insulin treatment on the phospholipid content of R3230AC mammary tumors, a hormonally responsive neoplasm, was studied. Diabetes was induced by administration of streptozotocin 3 days prior to tumor implantation. Protamine zinc insulin, 3 IU/rat twice daily, was administered to tumor-bearing rats for 3 days. Enzymatically dissociated tumor cells from diabetic animals showed significant increases in phosphatidyl choline, lysophosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, and phosphatidic acid, compared to controls. Diabetic animals treated with insulin displayed reductions in phosphatidyl choline, lysophosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, and phosphatidic acid to levels approximating those found in intact (control) animals. However, neither diabetes nor insulin treatment altered sphingomyelin levels. Mammary tumor cells from diabetic animals showed a 21% increase in DNA content compared to that in intact controls and treatment of diabetic animals with insulin lowered DNA level significantly. The responsiveness of both phospholipids and DNA content to changes in the insulin milieu of the host suggest that phospholipids may play an important role in mediating the effects of insulin on growth of R3230AC tumors.