Agreement assessment of tigecycline susceptibilities determined by the disk diffusion and broth microdilution methods among commonly encountered resistant bacterial isolates: results from the Tigecycline In Vitro Surveillance in Taiwan (TIST) study, 2008 to 2010

The Tigecycline In Vitro Surveillance in Taiwan (TIST) study, initiated in 2006, is a nationwide surveillance program designed to longitudinally monitor the in vitro activity of tigecycline against commonly encountered drug-resistant bacteria. This study compared the in vitro activity of tigecycline against 3,014 isolates of clinically important drug-resistant bacteria using the standard broth microdilution and disk diffusion methods. Species studied included methicillin-resistant Staphylococcus aureus (MRSA; n = 759), vancomycin-resistant Enterococcus faecium (VRE; n = 191), extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (n = 602), ESBL-producing Klebsiella pneumoniae (n = 736), and Acinetobacter baumannii (n = 726) that had been collected from patients treated between 2008 and 2010 at 20 hospitals in Taiwan. MICs and inhibition zone diameters were interpreted according to the currently recommended U.S. Food and Drug Administration (FDA) criteria and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. The MIC(90) values of tigecycline against MRSA, VRE, ESBL-producing E. coli, ESBL-producing K. pneumoniae, and A. baumannii were 0.5, 0.125, 0.5, 2, and 8 μg/ml, respectively. The total error rates between the two methods using the FDA criteria were high: 38.4% for ESBL-producing K. pneumoniae and 33.8% for A. baumannii. Using the EUCAST criteria, the total error rate was also high (54.6%) for A. baumannii isolates. The total error rates between these two methods were <5% for MRSA, VRE, and ESBL-producing E. coli. For routine susceptibility testing of ESBL-producing K. pneumoniae and A. baumannii against tigecycline, the broth microdilution method should be used because of the poor correlation of results between these two methods.

Safety and immunogenicity of a tetravalent polysaccharide vaccine against meningococcal disease

BACKGROUND/PURPOSE

Meningococcal disease, including meningitis and sepsis, usually follows an invasive infection by Neisseria meningitidis, and is a major cause of death and morbidity worldwide. Currently available meningococcal vaccines that consist of pure capsular polysaccharides (serogroups A, C, W-135 and Y) are generally safe and efficacious in adults and children aged > 2 years. The purpose of this study was to evaluate the immunogenicity, safety and reactogenicity of a single dose of GlaxoSmithKline Biologicals' Mencevax ACWY vaccine in healthy Taiwanese subjects aged 2-30 years.

METHODS

This open, single center, Phase III study was conducted in Taiwan. A single dose of the Mencevax ACWY vaccine was administered to subjects aged 2-30 years. Immunogenicity and safety of the vaccine were evaluated after vaccination.

RESULTS

The immunogenicity results obtained 1 month after vaccination with Mencevax ACWY vaccine indicated that the vaccine elicited a good immune response in vaccinees aged 2-30 years. This was both in terms of functional activity directed against meningococcal polysaccharide (A, C, W-135 and Y) as measured by serum bactericidal assay (> 93% activity against all serogroups), and specific IgG concentrations measured by ELISA (> 96% seropositivity to all serogroups).

CONCLUSION

The tetravalent polysaccharide Mencevax ACWY meningococcal vaccine was well tolerated and immunogenic in subjects aged 2-30 years in Taiwan.

Improvement in timing of antibiotic administration by using a prophylactic antibiotic record form

BACKGROUND/PURPOSE

To evaluate the effect of a form recording the timing of prophylactic antibiotic administration, antibiotics used, and treatment duration on the proper use of prophylactic antibiotics in patients undergoing four types of operations.

METHODS

This was a retrospective study in a 682-bed, university-affiliated, tertiary teaching hospital. Using the form developed, nurse practitioners recorded the timing of prophylactic antibiotic administration, antibiotics used, and treatment duration for patients undergoing three types of clean operations (total hip replacement, total knee replacement, thyroidectomy) and one type of clean-contaminated operation (hemorrhoidectomy). Patient records were identified by chart review after searching the hospital database. A case was defined by a principal or secondary procedure code for the four types of operations. Patients who received therapeutic antibiotics for documented preoperative infection were excluded.

RESULTS

A significant improvement (p<0.001; OR, 33.768; 95% CI, 4.304-264.951) in the use of prophylactic antibiotics was noted between the pre-intervention and intervention periods. Among the three criteria of antibiotic usage, the improvement in the appropriate timing of prophylactic antibiotics was significant (p<0.001; OR, 46.247; 95% CI, 5.891-363). The accuracy of the prophylactic antibiotic form in recording the timing of antibiotic administration, the choice of antibiotics, and the treatment duration was 84.2% (16/19), 89.4% (17/19), and 100% (19/19), respectively.

CONCLUSION

The prophylactic antibiotic form effectively decreased the inappropriate use of prophylactic antibiotics. Due to its high degree of reliability, this infection control measure can be used as a continuous monitoring system for prophylactic antibiotic use.

Aberrant induction of regulatory activity of CD4+CD25+ T cells by dendritic cells in HIV-infected persons with amebic liver abscess

To know why HIV-1-infected persons are particularly susceptible to amebic liver abscess (ALA), we investigated the role of CD4CD25 T cells in the susceptibility of HIV-1-infected persons to this disease. Herein we show, in early stage HIV-1-infected subjects, that CD4 T-cell responses to Entamoeba histolytica antigen (EhAg) were selectively impaired, especially in those with ALA. EhAg-specific CD4 T-cell responses were normalized by depletion of CD4CD25 cells or by addition of anti-cytotoxic T lymphocyte antigen 4 (CTLA4) antibody. Regulatory activity of CD4CD25 T cells to suppress the EhAg-specific CD4 T-cell response could be induced by EhAg-primed dendritic cells (DCs) in HIV-1-infected subjects, especially in those with ALA, but not in healthy controls. Exogenous Tat-incubated DCs derived from HIV-negative subjects also could upregulate CTLA4 expression on autologous CD4CD25 T cells and selectively suppress the EhAg-specific CD4 T-cell response. The results imply an interaction of the two pathogens: HIV-1, perhaps through the effect of Tat on DCs, may upregulate EhAg-specific regulatory T-cell activity to suppress T-cell response to E. histolytica, thus increasing the susceptibility to invasive amebiasis in even early-stage HIV-1-infected persons.

New concepts for organocatalysis

Organocatalysis, catalysis with low-molecular weight catalysts in which a metal is not part of the catalytic principle or the reaction substrate, can be as efficient and selective as metal- or biocatalysis. Important discoveries in this area include novel Lewis base-catalyzed enantioselective processes and, more recently, simple Brønsted acid organocatalysts that rival the efficiency of traditional metal-based asymmetric Lewis acid-catalysts. Contributions to organocatalysis from our laboratories include several new and broadly useful concepts such as enamine catalysis and asymmetric counteranion-directed catalysis. Our laboratory has discovered the proline-catalyzed direct asymmetric intermolecular aldol reaction and introduced several other organocatalytic reactions.

Endocarditis caused by Propionibacterium acnes: an easily ignored pathogen

Propionibacterium acnes, which usually considered as a contaminant, has been found to be an emerging pathogen in human diseases. We describe a case of prosthetic valve related endocarditis caused by P. acnes. Sequencing of the genetic coding of 16S ribosomal RNA was used to identify the pathogen and random amplified polymorphic DNA patterns further confirmed the persistent bacteraemia, which help to determine the diagnosis.

Community-onset Escherichia coli and Klebsiella pneumoniae bacteremia: influence of health care exposure on antimicrobial susceptibility

Three hundred forty-one case patients with Escherichia coli bacteremia and 173 case patients with Klebsiella pneumoniae bacteremia were enrolled in this prospective observational study to compare the clinical manifestations of infections in the 2 organisms and to delineate the change in resistance of isolates after health care exposure. Liver abscess, primary bacteremia, and respiratory tract infection were more commonly seen in patients with K. pneumoniae bacteremia, whereas urinary tract infection was more common in those with E. coli bacteremia. The influence of prior hospitalization on resistance of E. coli to some antibiotics could be observed for as long as 6 months after discharge. Patients undergoing procedures in the outpatient setting and nursing home residents also had infections with more resistant E. coli strains than those without hospital exposure within the previous year. However, no difference in resistance was observed in K. pneumoniae isolates from patients in different clinical settings.

In vitro maturation potential of monocyte-derived dendritic cells is impaired in patients with spinal cord injury: a case-control study

OBJECTIVE

To determine whether the T-cell reactivity and maturation potential of dendritic cells are impaired in subjects with spinal cord injury (SCI).

DESIGN

Cross-sectional, case-control study.

SETTING

University hospital in Taiwan.

PARTICIPANTS

Thirty male SCI subjects, including 14 with paraplegia and 16 with tetraplegia, and 30 age- and sex-matched healthy controls.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

CD4+ and CD8+ T-cell reactivity was assessed by lymphoproliferative response (LPR) and CD69 expression in response to stimulation with antigens, anti-CD3 monoclonal antibody, and mitogen. Dendritic cell maturation potential was assessed by phenotypic (CD80 and CD83 expression in stimulated monocyte-derived dendritic cells) and functional (the LPR of alloreactive T cells in mixed leukocyte reactions) analysis.

RESULTS

The potential of phenotypic and functional maturation of dendritic cells of subjects with SCI was significantly impaired compared with healthy controls, and that potential was worse for tetraplegic patients than for paraplegic patients. However, no significant difference was found in T-cell responses of CD4+ and CD8+ subsets between subjects with SCI and healthy controls.

CONCLUSIONS

Impaired maturation potential of dendritic cells is a novel defect in innate immunity in people with SCI.

Dose reduction for the management of indinavir-related toxicity in human immunodeficiency virus type 1-infected patients in Taiwan: clinical and pharmacokinetic assessment

This study evaluated the feasibility of reducing the indinavir (IDV) dosage in Taiwanese patients receiving the standard IDV/ritonavir (RTV) dosage of 800/100 mg twice a day who had undetectable plasma human immunodeficiency virus type 1 (HIV-1) RNA but had developed IDV-related toxicities. After dosage reduction to IDV/RTV 600/100 mg twice a day, the dose-related toxicity decreased and plasma HIV RNA remained undetectable at 24 weeks post-switch in all patients. The maximal plasma concentration (Cmax) and area under the plasma concentration-time curve of IDV decreased significantly (median, 6.3 vs 4.3 microg/mL and 1892 vs 1292 microg.min/mL, p=0.01 and 0.001, respectively) but the minimal plasma concentration remained at a similar level (median, 1.0 vs 0.8 microg/mL, p=0.12). This study found that the reduction in the dosage of IDV in HIV-1 infected patients receiving the standard IDV/RTV regimen guided by therapeutic drug monitoring decreased the Cmax, dose-related toxicity and medical cost without compromising viral control.

SepticCandida kruseithrombophlebitis of inferior vena cava with persistent fungemia successfully treated by new antifungal agents

Treatment of Candida krusei fungemia can be problematic. We describe a 44-year-old critically ill, non-immunocompromised patient who had persistent Candida krusei fungemia complicated with septic thrombophlebitis of the inferior vena cava. Successful treatment was achieved by parenteral caspofungin followed by prolonged oral voriconazole. Persistent fungemia in the face of ongoing antifungal therapy and prompt removal of central line should alert physicians to the diagnosis of septic thrombophlebitis. Though combined therapy with amphotericin B and surgical intervention probably remains the treatment of choice, prolonged new antifungal agents, which have better efficacy, tolerability and bioavailability, may be a useful alternative where the central veins are relatively inaccessible or the patient is at high operative risk.

Age Distribution for T Cell Reactivity to Vaccinia Virus in a Healthy Population

The potential for bioterrorism involving smallpox has led to a debate about the durability of protective immunity against smallpox from vaccination. By assessing the T cell reactivity to vaccinia virus in a healthy population, we show that subjects who were vaccinated within the past 3 decades and who have a visible vaccination scar had remarkable T cell reactivity. However, person who were vaccinated within the past 3 decades but who do not have a scar and those who were vaccinated >4 decades ago had responses as low as those in unvaccinated subjects. Thus, we estimate that the significant T cell memory response to vaccinia virus from successful vaccination may persist for only 20-30 years. Furthermore, we found the vaccinia-specific cellular immunity could be easily assessed by determination of the frequencies of vaccinia-specific CD69 expression on T cell subsets. These data may help in the development of public health strategies to counter bioterrorism threats associated with smallpox.

Differential impact of late-stage HIV-1 infection on in vitro and in vivo maturation of myeloid dendritic cells

The functional and phenotypic maturation of myeloid dendritic cells (DCs), circulating and monocyte-derived, from subjects at different stages of HIV-1 infection was evaluated. The results showed that the capacity of circulating DCs was significantly impaired in subjects with CD4+ T cell counts of <200/microL, correlated with the potential of CD40 ligand expression on CD4+ T cells (R = 0.84; P = 0.002), and improved with successful antiretroviral therapy. However, the function and phenotype of monocyte-derived DCs generated by in vitro culture from subjects at any stage of HIV-1 infection were similar to those in uninfected healthy subjects. Our findings suggest that although the potential of myeloid DC precursors to achieve full maturation is preserved in subjects with late-stage HIV-1 infection, in vivo maturation of myeloid DCs was impaired in these subjects, which may be due to decreased potential of CD40 ligand expression on CD4+ T cells. That myeloid DCs fail to achieve full maturation in vivo in late-stage HIV-1 infection may contribute to the failure to induce effective cellular immunity against HIV-1 and opportunistic pathogens.

Cross-limb vascular shunting as an auxiliary to major limb revascularisation

A 40-year-old male motorcyclist suffered a near-total amputation of his right foot. His limb was successfully salvaged with the aid of a cross-leg vascular shunt. Temporary arterial flow from the contralateral limb was transmitted via a pressure monitor tube to perfuse the avulsed part. This allowed the surgeon to carry out unhurried wound debridement, dissection of vital structures and skeletal fixation. The cannulation port was placed well distal to the proposed definitive anas<$>tomosis, to reduce damage to the endothelium. This procedure could be a valuable adjunct in major limb replantation, particularly in cases of prolonged ischaemia.

Association between cytomegalovirus-specific reactivity of T cell subsets and development of cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome

The association between cytomegalovirus (CMV)-specific reactivity of T cell subsets and development of CMV retinitis (CMV-R) was prospectively studied in 50 CMV-seropositive AIDS patients. The frequency of CMV-specific CD69 expression on CD8 T cells was similar in patients with and patients without CMV-R (median, 1.0% vs. 1.2%; P=.14). However, the frequency of CMV-specific CD69 expression on CD4 T cells was significantly lower in patients with CMV-R than in those without CMV-R (median, 0.4% vs. 2.25%; P<.001). CMV-specific CD4 T cell reactivity in patients who developed CMV-R shortly after starting highly active antiretroviral therapy (HAART) remained low, although the CD4 cell counts increased markedly. Therefore, development of CMV-R is associated with a poor CMV-specific reactivity of CD4 T cells but not with poor reactivity of CD8 T cells. Development of CMV-R after initiation of HAART is associated with a poor reconstitution of CMV-specific immune response, rather than with immune rebound.

Kinetics of antigen-induced phenotypic and functional maturation of human monocyte-derived dendritic cells

Dendritic cells (DCs), a critical component of innate immunity, are the most potent APCs. When DCs mature, they can elicit strong T cell responses. We studied the kinetics of Ag-induced phenotypic and functional maturation of human monocyte-derived DCs using an in vitro T cell-independent culture system. With this model, we herein show that an Ag that has recently or repetitively been exposed ("exposed Ag") rapidly induces a high level of maturation; however, an Ag that has never or only remotely been exposed ("unexposed Ag") slowly induces a low level of maturation. The kinetics of Ag-induced maturation of DCs possibly implies a novel mechanism for immunological memory that would provide maximal host protection from repetitively invading pathogens in the environment.

Sewage sludge ash characteristics and its potential applications

This study investigated the characteristics of SSA in Taiwan area. The potential applications of SSA reuse were also evaluated. Four major characteristics of SSA, including chemical compositions, pozzolanic properties, physical properties, and surface properties were analyzed. Experimental results found that SSA was a complex mixture of burnt residues of sludge biomass and minerals. The major chemical compositions of SSA were silicon oxide, aluminium oxide, and iron oxide. The most predominant silicon oxide occupied 41.3 to 56.1% of overall SSA weight and approximately 60% weight of silicon oxide in SSA was amorphous type. Due to the effect of amorphous silicon oxide, the SSA exerted pozzolanic activity. The strength activity index (SAI) value of SSA was between 53.6 and 74.3%. The SSA particles were also the agglomeration of finer grains between 0.1 and 1 microm of size. Therefore the SSA was porous with irregular particles with significant pore surface area. Additionally, the SSA exerted negative surface charge and cation-exchange capacity in neutral aqueous phase. Based on the SSA characteristics found in this study, four potential applications of SSA reuse were evaluated. These technologies included reusing as fine aggregate, reusing as pozzolanic material, melting or vitrification treatment, and reusing as adsorbent. In addition, the advantages and disadvantages of the above potential applications of SSA were discussed.

Restoration of cellular immunity against tuberculosis in patients coinfected with HIV-1 and tuberculosis with effective antiretroviral therapy: assessment by determination of CD69 expression on T cells after tuberculin stimulation

Whether immunity against opportunistic pathogens can be fully restored by control of HIV-1 replication remains open to question. This longitudinal study was conducted to measure anti-tuberculosis (TB) cellular immunity in 13 HIV-1/TB-coinfected patients effectively treated by highly active antiretroviral therapy (HAART) in a period of 12 months. In this study, anti-TB cellular immunity was assessed by determining the frequencies of CD 69 expression on CD4+ and CD8+ T cells in response to purified protein derivative (PPD) stimulation (abbreviated as %CD4+CD69 to PPD and %CD8+CD69 to PPD). Here, we show that %CD4+CD69 to PPD correlated with the results of tuberculin skin tests and interferon-gamma (IFN-gamma) production from PPD-stimulated CD4+ T cells, and %CD8+CD69 to PPD also correlated with CD8+ T cell-mediated PPD-specific cytolysis. In overall analysis for these 13 patients, both %CD4+CD69 to PPD and %CD8+CD69 to PPD increased significantly during the 12 months (p =. 003 and p <.001, respectively). However, we found %CD4+CD69 to PPD or %CD8+CD69 to PPD failed to increase substantially in some patients (i.e., immunologic nonresponders). A significantly higher proportion of patients whose baseline CD4+ count was <50 cells/mm3 were considered to be CD4+ nonresponders compared with those whose baseline CD4+ count was >50 cells/mm3. Furthermore, baseline CD4+ cell count in nonresponders is significantly lower than that in responders, although the effectiveness of HAART did not differ between them. Our results indicate that PPD-specific frequencies of CD69 expression may be used as surrogate markers of anti-TB cellular immunity. By this method, we show that full reconstitution of anti-TB cellular immunity in HIV-1/TB coinfected patients may not necessarily be achieved by "successful" HAART and may be influenced by the baseline immune status when HAART is started. These data suggest that the decision to discontinue secondary prophylaxis for opportunistic infections should be cautiously made, even when the CD4+ cell count has significantly increased.

Exposure to and actions against passive smoking in non-smoking pregnant women in Guangzhou, China

BACKGROUND

The objective was to describe the extent of passive smoking exposure and preventive actions against passive smoking in non-smoking pregnant women and to analyze factors associated with preventive actions.

METHODS

This was a cross-sectional survey on 1449 never-smoking pregnant women who made their first prenatal visit to the Women and Children's Hospital of Guangzhou, China during 1996-97.

RESULTS

60.2% (95% Confidence Interval 57.7%-62.7%) of the never-smoking pregnant women had a husband who currently smoked. Women with smoking husbands (n=872) were more exposed to ETS than those with non-smoking husbands (n=577) at home (71% vs. 33%), in public places (77% vs. 66%) and at work (60% vs. 50% of working women), and they took less actions against passive smoking in public places. Women with better education and knowledge on smoking and passive smoking had stronger preventive actions.

CONCLUSIONS

Non-smoking pregnant women in China are often exposed to passive smoking and their preventive actions are weak. Passive smoking is an important obstetric and public health problem in developing countries and deserves urgent international attention.

Free anterolateral thigh flap for reconstruction of head and neck defects following cancer ablation

Thirty-seven consecutive free anterolateral thigh flaps in 36 patients were transferred for reconstruction of head and neck defects following cancer ablation between January of 1997 and June of 1998. The success rate was 97 percent (36 of 37), with one flap lost due to a twisted perforator. The anatomic variations and length of the vascular pedicle were investigated to obtain better knowledge of anatomy and to avoid several surgical pitfalls when it is used for head and neck reconstruction. The cutaneous perforators were always found and presented as musculocutaneous or septocutaneous perforators in this series of 37 anterolateral thigh flaps. They were classified into four types according to the perforator derivation and the direction in which it traversed the vastus lateralis muscle. In type I, vertical musculocutaneous perforators from the descending branch of the lateral circumflex femoral artery were found in 56.8 percent of cases (21 of 37), and they were 4.83 +/- 2.04 cm in length. In type II, horizontal musculocutaneous perforators from the transverse branch of the lateral circumflex femoral artery were found in 27.0 percent of cases (10 of 37), and they were 6.77 +/- 3.48 cm in length. In type III, vertical septocutaneous perforators from the descending branch of the lateral circumflex femoral artery were found in 10.8 percent of cases (4 of 37), and they were 3.60 +/- 1.47 cm in length. In type IV, horizontal septocutaneous perforators from the transverse branch of the lateral circumflex femoral artery were found in 5.4 percent of cases (2 of 37). They were 7.75 +/- 1.06 cm in length. The average length of vascular pedicle was 12.01 +/- 1.50 cm, and the arterial diameter was around 2.0 to 2.5 mm; two accompanying veins varied from 1.8 to 3.0 mm and were suitable for anastomosis with the neck vessels. Reconstruction of one-layer defect, external skin or intraoral lining, was carried out in 18 cases, through-and-through defect in 17 cases, and composite mandibular defect in two cases. With increasing knowledge of anatomy and refinements of surgical technique, the anterolateral thigh flap can be harvested safely to reconstruct complicated defects of head and neck following cancer ablation with only minimal donor-site morbidity.

Schistosoma mansoni: the ultrastructure of larval morphogenesis in Biomphalaria glabrata and of associated host-parasite interactions

An electron microscopic study has been carried out to describe the transformation of the miracidium of S. mansoni into the mother sporocysts in the susceptible B. glabrata and the associated host-parasite interactions. The miracidium enters the snail host without morphological alterations. Within 3 hr after entering, all the ciliary epidermal plates of the miracidium are discarded. A new tegument is quickly formed by 5 hr postinfection by the expansion of epidermal ridges. The rapid formation of the new tegument reflects the participation of membrane-bound vesicles in the ridge cytons. The membranes of these vesicles become the new tegument membranes with the discharge of their electron-dense contents into the snail tissues. The vesicular contents discharged into the tissues apparently prevent snail amoebocytes (phagocytes) from attachment to the parasite tegument and thus prevent their interference with the further development of the postmiracidium. If a postmiracidium fails to mobilize membrane-bound vesicles in the formation of tegument, the parasite becomes surrounded by closely attached concentric layers of fibroblasts formed by amoebocytes and histiocytes within 24 hr. The membrane-bound vesicles are present in small numbers in the ridge cytons of the miracidium and become numerous in the postmiracidium stage and with many migrate to the ridges through connecting bridges within 24 hr. By 3 days postinfection when extensive microvilli have formed on the tegument the vesicles have disappeared and are replaced by mitochondria, ribosomes and complex carbohydrate particles. Many fibroblasts in the snail connective tissues have phagocytic capacities and are regarded as snail tissue histiocytes or fixed amoebocytes that eventually may become hypertrophic and detached.

[Application of Ilizarov's external fixator on the basis of biology]

Ilizarov's biology includes that, in the presence of tension and stress, both regeneration of bone and soft tissues with cellular proliferation and their biological synthesis become vigorous. The Ilizarov's external fixator has five functions namely: compression, distraction, de-angulation, derotation and translocation. The principles of this procedure include: corticotomy instead of conventional osteotomy, placement of 4-5 sets of 1.5 mm wires transfixed in the bones at different levels under tension of 70-110 kg on the circular rings without acute diastasis until the 5 th to 7th day, and then, callotasis-callus distraction. The quality and quantity of the regenerated bone within the widening distraction gap are closely related to the maximum preservation of bone marrow and periosseous blood supply, and a distraction of 1 mm per day and preferably done by 4 times 0.25 mm each time should be emphasized. Experiences in 17 cases of pseudarthrosis and unequal length of leg treated with Ilizarov's technique are presented.

Isolation of antigens with proteolytic activity from Coccidioides immitis

Three antigens with proteolytic activity have been isolated from crude, water-soluble fractions of the saprobic phase of the fungal pathogen Coccidioides immitis. Two proteinases, identified in our immunoelectrophoresis reference system as Ag11 and AgCS, were isolated from the soluble conidial wall fraction (SCWF). Ag11 was previously shown to be a serine proteinase and was characterized in this study as a 60-kilodalton (kDa) fraction by gel filtration (GF). The purified proteinase demonstrated little or no reactivity with 21 serum samples from coccidioidomycosis patients in the enzyme-linked immunosorbent assay; this may be due to limited presentation of this antigen to the host during the course of coccidioidomycosis. AgCS was separated by GF chromatography into two fractions identified by molecular masses of 39 and 19 kDa. Most proteolytic activity was shown by substrate gel electrophoresis to be associated with the lower-molecular-mass fraction. AgCS was reactive with 18 of the 21 serum samples and shown to be the major component of a heat-stable antigen previously reported to be immunospecific for C. immitis. The third antigen with proteolytic activity was isolated from the 5-day mycelial culture filtrate and identified by GF as a 56-kDa fraction. Uniformly high levels of immunoreactivity between 18 of the 21 patient sera and the 56-kDa antigen were demonstrated. Antigens with proteolytic activity may play important roles in fungus-host interactions as well as morphogenesis of the pathogen.

Leishmania mexicana: comparative fine structure of amastigotes and promastigotes in vitro and in vivo

Amastigotes of Leishmania mexicana pifanoi were cultivated by serial transfers in cell-free medium UM-54 at 33 and 35 C. Electron microscopy was used to analyze the structural relationships among promastigotes, axenically cultured amastigotes, and amastigotes in footpads of infected hamsters. These studies revealed very close structural similarities between culture and hamster derived amastigotes. However, both of these amastigotes differed from the promastigotes in the following aspects. The flagellum of promastigotes contained a paraxial rod originating at the axosome level within the flagellar pocket, whereas the flagellum of amastigotes lacks this structure. The flagellar pocket of promastigotes was usually small whereas amastigotes had a distended reservoir. Subpellicular microtubules of promastigotes terminated at the posterior end, whereas those of amastigotes ended subterminally. Membrane bounded vesicles were present only in amastigotes. These results along with the biologic and antigenic comparisons indicate that amastigotes obtained from axenic cultures are related very closely to amastigotes from infected hamster footpads and that their relationship to promastigotes is far more distant.

Novobiocin antagonism of amastigotes of Trypanosoma cruzi growing in cell-free medium

Inhibitors of the enzyme bacterial topoisomerase II (DNA gyrase) were evaluated for activity against Trypanosoma cruzi (Brazil strain), based on the theoretical need for a topoisomerase II in the replication of the kinetoplast DNA network. Novobiocin (500 micrograms/ml) antagonized amastigotes of T. cruzi growing in a cell-free medium at 37 degrees C, as manifested by inhibition of multiplication, abnormal morphology of Giemsa-stained organisms, and delayed or absent growth of cells upon subculturing in a drug-free medium. In contrast, novobiocin (1,000 micrograms/ml) essentially had no effect on the multiplication and motility of epimastigotes growing in a cell-free medium at 27 degrees C. This resistance of epimastigotes represented a difference in the physiology of this morphologic stage and not in the temperature of experimentation, because novobiocin inhibited multiplication of amastigotes at 27 degrees C as well and accelerated transformation to epimastigotes. With T. cruzi growing within cultured human fibroblasts, novobiocin (200 micrograms/ml) markedly inhibited transformation of intracellular amastigotes to trypomastigotes. Clorobiocin, a structural analog of novobiocin and likewise an inhibitor of the B subunit of bacterial topoisomerase II, was five times more potent on a molar basis than novobiocin was in antagonism of amastigotes growing in a cell-free medium and did not antagonize epimastigotes. Coumermycin A1, another analog of novobiocin, and five 4-quinolone antibacterial agents, antagonists of the A subunit of bacterial topoisomerase II, inhibited neither amastigotes nor epimastigotes. These experiments indicate that novobiocin and clorobiocin represent a new structural class of drugs with activity against T. cruzi. Whether the mechanism of action of these drugs involves antagonism of a T. cruzi topoisomerase II or an unrelated target is yet to be determined.

Leishmanial infections: a consideration in travellers returning from abroad

Seven cases of leishmaniasis, including a fatal case of visceral leishmaniasis and 6 cases of dermal leishmaniasis, were seen in Boston over a four-year period. Diagnosis was made by isolation of organisms in culture or by identification of organisms in stained preparations of tissue. Proper management of patients with leishmanial infections requires an appreciation of the geographical strain differences of each species.

Establishment of clones of Trypanosoma cruzi and their characterization in vitro and in vivo

An efficient technique for isolating clones of Trypanosoma cruzi from cultures and from animals has been developed. It is based on the inoculation of one organism, obtained by serial dilutions of cultured epimastigotes or isolated blood stream trypomastigotes, into enriched NNN medium (NNN-F:93). The cloning efficiency (percentage of positive cultures over the number inoculated) was 70% for cultured epimastigotes and 30-40% for blood-stream trypomastigotes. In vitro cultural characteristics of 14 secondary clones of an avirulent strain indicated that 12 clones grew in the F-94 medium primarily as epimastigotes at 27 degrees C and exclusively as amastigotes at 37 degrees C; 2 clones grew in F-94 medium primarily as amastigotes regardless of incubation temperature (27 degrees C or 37 degrees C). In vivo characterization of 7 clones from 2 virulent strains indicated that the virulence of individual clones was low immediately after isolation in NNN-F:93 medium, but the virulence of some clones returned to the level of the parent strain after more than 8 serial passages in CD-1 mice.