Enhancement of antibiotic susceptibility ofStenotrophomonas maltophiliausing a polyclonal antibody developed against an ABC multidrug efflux pump

Stenotrophomonas maltophilia is an emerging nosocomial pathogen capable of causing healthcare-associated infections, including pneumonia and bacteremia. Intrinsic resistance in S. maltophilia is exhibited towards many broad-spectrum antibiotics, and treatment recommendations are controversial. One of the major causes of antimicrobial resistance is attributed to a robust array of efflux pumps that extrude drug compounds from the cell. Using checkerboard and growth kinetic assays, we evaluated the in vitro activity of a polyclonal antibody raised against an ATP-binding cassette efflux protein in S. maltophilia. Six clinical strains of S. maltophilia and one type strain were challenged with co-trimoxazole, ticarcillin–clavulanate, and ciprofloxacin, alone and in combination with antibody. One clinical strain was tested by growth curve experiments for each antibiotic–antibody combination. The use of antibody resulted in significantly increased susceptibility in 71.4% (15/21) of treatments tested, with 33.3% displaying synergy and 38.1% an additive effect. In growth kinetic studies, synergy was obtained for each antibiotic–antibody combination. Thus, the use of antibody raised against multidrug efflux pumps for the treatment of multidrug-resistant organisms warrants further investigation. Antibody targeting substrate recognition sites, or other functionally important epitopes, may lead to inhibition of multiple efflux pumps that share the same substrate and is an attractive area that should be explored.

Molecular cloning and characterization of SmrA, a novel ABC multidrug efflux pump from Stenotrophomonas maltophilia

OBJECTIVES

Stenotrophomonas maltophilia is an emerging nosocomial pathogen that can cause difficult-to-treat infections and exhibits significant degrees of poorly understood multidrug resistance (MDR). The aim of this study was to identify and characterize a multidrug ATP-binding cassette (ABC) efflux pump in S. maltophilia.

METHODS

SmrA was identified in the S. maltophilia genome based on the detection of ABC transporter conserved motifs and alignment with experimentally proven MDR ABC transporters. The smrA gene was cloned and expressed in the hypersusceptible acrAB mutant Escherichia coli strain SM1411. The resistance to several antimicrobial agents was tested using Stokes' disc diffusion and broth microdilution MIC methods. Norfloxacin accumulation and efflux assays were performed using a fluorescence method with and without the efflux pump inhibitors sodium O-vanadate and reserpine.

RESULTS

Cloning and expression of smrA in Escherichia coli conferred increased resistance to structurally unrelated compounds, including fluoroquinolones, tetracycline, doxorubicin and multiple dyes. Moreover, the expression of smrA in E. coli reduced norfloxacin uptake and enhanced its efflux, features that could be inhibited by the ABC efflux pump inhibitors.

CONCLUSIONS

SmrA is a member of the ABC multidrug efflux pump family. The findings warrant further study of the role of this molecule in S. maltophilia isolates, to estimate the potential impact of this system in antimicrobial resistance.

Recommendations for managing Aspergillus osteomyelitis and joint infections based on a review of the literature

OBJECTIVES

To produce recommendations for the management of Aspergillus osteomyelitis and joint infections.

METHODS

Published literature was surveyed to identify both case reports of Aspergillus osteomyelitis and joint infections and anti-fungal pharmacology of anti-fungal agents. Included in the pharmacological review was an assessment of new and investigational anti-fungals to consider their potential role in the management of this infection.

RESULTS

Successful treatments, identified from the cases reviewed, were based on combination anti-fungal therapy with one agent having good bone penetration and one having reliable anti-Aspergillus activity.

CONCLUSIONS

For the management of serious Aspergillus osteomyleitis/joint infections amphotericin B in combination with flucytosine is recommended. A number of second line treatment combinations are identified. Monotherapy is appropriate with an azole in clinically stable patients.

A randomized, blinded, multicenter trial of lipid-associated amphotericin B alone versus in combination with an antibody-based inhibitor of heat shock protein 90 in patients with invasive candidiasis

BACKGROUND

Mycograb (NeuTec Pharma) is a human recombinant monoclonal antibody against heat shock protein 90 that, in laboratory studies, was revealed to have synergy with amphotericin B against a broad spectrum of Candida species.

METHODS

A double-blind, randomized study was conducted to determine whether lipid-associated amphotericin B plus Mycograb was superior to amphotericin B plus placebo in patients with culture-confirmed invasive candidiasis. Patients received a lipid-associated formulation of amphotericin B plus a 5-day course of Mycograb or placebo, having been stratified on the basis of Candida species (Candida albicans vs. non-albicans species of Candida). Inclusion criteria included clinical evidence of active infection at trial entry plus growth of Candida species on culture of a specimen from a clinically significant site within 3 days after initiation of study treatment. The primary efficacy variable was overall response to treatment (clinical and mycological resolution) by day 10.

RESULTS

Of the 139 patients enrolled from Europe and the United States, 117 were included in the modified intention-to-treat population. A complete overall response by day 10 was obtained for 29 (48%) of 61 patients in the amphotericin B group, compared with 47 (84%) of 56 patients in the Mycograb combination therapy group (odds ratio [OR], 5.8; 95% confidence interval [CI], 2.41-13.79; P<.001). The following efficacy criteria were also met: clinical response (52% vs. 86%; OR, 5.4; 95% CI, 2.21-13.39; P<.001), mycological response (54% vs. 89%; OR, 7.1; 95% CI, 2.64-18.94; P<.001), Candida-attributable mortality (18% vs. 4%; OR, 0.2; 95% CI, 0.04-0.80; P = .025), and rate of culture-confirmed clearance of the infection (hazard ratio, 2.3; 95% CI, 1.4-3.8; P = .001). Mycograb was well tolerated.

CONCLUSIONS

Mycograb plus lipid-associated amphotericin B produced significant clinical and culture-confirmed improvement in outcome for patients with invasive candidiasis.

Genetically recombinant antibodies: new therapeutics against candidiasis

Historically, the therapy of serious fungal infection has been dominated by monotherapy with the polyene antibiotic amphotericin B. Clinical failures, side effects, the lack of alternatives and the toxicity of this drug have heightened the need to produce alternative therapies, which have included fluconazole, voriconazole and caspofungin. The observation that recovery from disseminated candidiasis was associated with an antibody response to the 47 kDa Candida heat-shock protein (HSP)90 homologue, coupled with the ability to sequence all the antibodies from patients who have recovered from the infection and to re-express the dominant ones as fragments in Escherichia coli, has opened the possibility of immunotherapy. The first recombinant antibody fragment, Mycograb (Neu Tec Pharma plc), against Candida HSP90 is now in clinical trials in patients with disseminated candidiasis in Europe and the US. Laboratory and early clinical data support the concept of synergy between Mycograb and amphotericin B. This should improve outcome and diminish the risk of resistance occurring to either drug, without an increase in toxicity, as this should be minimal in a human antibody fragment representing the natural antibody that a patient produces on recovery.

The diagnosis of hepatosplenic candidiasis by DNA analysis of tissue biopsy and serum

Hepatosplenic candidiasis is traditionally diagnosed by blood culture, magnetic resonance imaging (MRI), and histological analysis. The limitations of these methods include: low sensitivity (blood culture) and failure to isolate the organism (MRI/histology). This report describes a case of hepatosplenic candidiasis diagnosed by simultaneous polymerase chain reaction (PCR) analysis of liver biopsy and serum. PCR of biopsy and/or serum may offer a sensitive and specific diagnostic test for hepatosplenic candidiasis. Candida species can be identified, which helps guide antifungal chemotherapy, an important aspect in this difficult to treat infection.

Preclinical assessment of the efficacy of mycograb, a human recombinant antibody against fungal HSP90

Mycograb (NeuTec Pharma plc) is a human genetically recombinant antibody against fungal heat shock protein 90 (HSP90). Antibody to HSP90 is closely associated with recovery in patients with invasive candidiasis who are receiving amphotericin B (AMB). Using in vitro assays developed for efficacy assessment of chemotherapeutic antifungal drugs, Mycograb showed activity against a wide range of yeast species (MICs against Candida albicans [fluconazole [FLC]-sensitive and FLC-resistant strains], Candida krusei, Candida tropicalis, Candida glabrata, and Candida parapsilosis, 128 to 256 microg/ml). Mycograb (4 or 8 microg/ml) showed synergy with AMB, the fractional inhibitory index being 0.09 to 0.31. Synergy was not evident with FLC, except for FLC-sensitive C. albicans. Murine kinetics showed that Mycograb at 2 mg/kg produced a maximum concentration of drug in serum of 4.7 microg/ml, a half-life at alpha phase of 3.75 min, a half-life at beta phase of 2.34 h, and an area under the concentration-time curve from 0 to t h of 155 microg. min/ml. Mycograb (2 mg/kg) alone produced significant improvement in murine candidiasis caused by each species: (i). a reduction (Scheffe's test, P < 0.05) in the mean organ colony count for the FLC-resistant strain of C. albicans (kidney, liver, and spleen), C. krusei (liver and spleen), C. glabrata (liver and spleen), C. tropicalis (kidney), and C. parapsilosis (kidney, liver, and spleen) and (ii). a statistically significant increase in the number of negative biopsy specimens (Fisher's exact test, P < 0.05) for C. glabrata (kidney), C. tropicalis (liver and spleen), and C. parapsilosis (liver). AMB (0.6 mg/kg) alone cleared the C. tropicalis infection but failed to clear infections caused by C. albicans, C. krusei, C. glabrata, or C. parapsilosis. Synergy with AMB, defined as an increase (Fisher's exact test, P < 0.05) in the number of negative biopsy specimens compared with those obtained using AMB alone, occurred with the FLC-resistant strain of C. albicans (kidney), C. krusei (spleen), C. glabrata (spleen), and C. parapsilosis (liver and spleen). Only by combining Mycograb with AMB was complete resolution of infection achieved for C. albicans, C. krusei, and C. glabrata.

The role of antibodies against hsp90 in the treatment of fungal infections

Advances in antibody engineering have solved many of the problems inherent in traditional sources of antibodies, and about a quarter of all biotechnology-based drugs now in development are antibodies. This has come at a time when it is apparent that reliance on antibiotics alone is beginning to select out resistant pathogens, fungi being a prime example. The development of antibody-based therapeutics, such as Mycograb, against novel fungal targets offers a new approach to combating the spread of resistance and reducing mortality.

Identification of ABC transporters in vancomycin-resistant Enterococcus faecium as potential targets for antibody therapy

The occurrence of an outbreak of septicaemias due to vancomycin-resistant Enterococcus faecium (VRE), in Manchester, UK, provided an opportunity to examine the antibody responses in patients infected by the same strain. Immunoblotting sera from 24 cases, six of whom died, showed an immunodominant cluster of antigens at 34, 54 and 97 kDa, with a statistically significant correlate between survival and immunoglobulin G to the 34 and 97 kDa bands (P<0.05). Screening a genomic expression library of VRE with seropositive serum and peritoneal dialysate from a survivor gave a recombinant clone with two contiguous open reading frames, the derived amino acid sequences of which both showed sequence homologue with ABC transporters, with a Walker A and Walker B motif and the signature sequence LSGGQ. The first open reading frame (putative VRE ABC1) showed 57% homologue with YbxA from Bacillus subtilis. A partial sequence (putative VRE ABC2) was also obtained, in the same recombinant clone, of a second ABC transporter with 72% homologue with ybaE from B. subtilis. Affinity selection with the seropositive serum and peritoneal dialysate used to screen the library showed that the eluted antibody bound to the 97, 54, 34 and 30 kDa bands. Direct amino acid sequencing identified this as a possible ABC transporter. Rabbit antiserum against peptides representing Walker A and an area adjacent to the Walker B site cross-reacted with bands at 34, 54, 97, 110 kDa and at 30, 34 and 54 kDa respectively. This therefore appeared to be an immunodominant complex of ABC transporters of which the smallest was the 30 kDa antigen. Epitope mapping of this antigen with seropositive patients' sera delineated three linear epitopes (KVGIV, FGPKNF and RVAI). The Walker A site represented by peptide 1 (GHNGSGKSTLAKTIN), epitope RVAI represented by peptides 2 (MRRVAIAGVLAMPRE) and 3 (ELSGGQMRRVAIAGV), epitope KVGIV represented by peptide 4 (LKPIRKKVGIVFQFP), and recombinant VRE ABC1 and VRE ABC2 expressed in Escherichia coli pBAD were then used to isolate human genetically recombinant antibodies from a phage antibody display library. An assessment of the protective potential of these antibodies was carried out in a mouse model of the infection. This study suggests that an ABC transporter homologue could be a target for antibody therapy against VRE infections.

Antifungal antibodies: a new approach to the treatment of systemic candidiasis

Antibody-based therapeutics have come of age, with advances in the genetic engineering of recombinant antibodies allowing application of a growing knowledge of the immunopathology of diseases to the development of novel drugs. For infections such as systemic candidiasis, which still have a mortality of 40 to 50%, antifungal antibodies could provide long-awaited novel therapies for use in combination with antifungal agents. They may also evolve into safe, broad-spectrum agents for prophylaxis in high-risk immunocompromised patients. Mycograb, a human genetically recombinant antibody against heat shock protein 90 (hsp90), has just started trials in patients with systemic candidiasis.

Analysis of 42 cases of septicemia caused by an epidemic strain of methicillin-resistant Staphylococcus aureus: evidence of resistance to vancomycin

Recent case reports of vancomycin treatment failures in the United States, Japan, and France have prompted a retrospective analysis of 42 cases of septicemia caused by epidemic methicillin-resistant Staphylococcus aureus strain 15 (EMRSA-15), which is the most prevalent epidemic strain of methicillin-resistant S. aureus in the United Kingdom; all cases occurred in a teaching hospital in Manchester, United Kingdom, between 1994 and 1998. Mortality was lowest (4%) in patients with rifampin-susceptible isolates treated with vancomycin and rifampin. It rose to 38% in patients who were treated with both antibiotics but in whom the organism became resistant to rifampin during therapy, and it reached 78% in patients who had rifampin-resistant isolates or in whom rifampin was contraindicated (P<.0001; Fisher exact test, 2-tailed). All isolates were susceptible to vancomycin by conventional laboratory testing, but susceptibility was lost by growth in vancomycin in vitro, becoming resistant at a minimum inhibitory concentration of 8 mg/L. This was associated with accumulation of cell-wall material. The deoxyribonucleic acid fingerprint remained unchanged. This study suggests that rifampin played a key role in the prevention of deaths caused by an epidemic strain of methicillin-resistant S. aureus that readily gave rise to a subpopulation with reduced susceptibility to vancomycin.

Over-expression of Saccharomyces cerevisiae hsp90 enhances the virulence of this yeast in mice

Saccharomyces cerevisiae, a yeast of low pathogenic potential, is a rare but well-documented cause of invasive infections in humans. The yeast Candida albicans is a much commoner cause of significant and life-threatening infections. In such infections the heat shock protein hsp90 is an immunodominant antigen associated with protective humoral immunity. In this study it was shown that over-expression of S. cerevisiae hsp90, the amino acid sequence of which shows 84% identity to C. albicans hsp90, significantly increased the virulence of a laboratory strain of S. cerevisiae in mice, both in terms of colony counts in the kidney, liver, and spleen, and in terms of mortality. This is the first direct evidence that hsp90 is a virulence factor.

Antibodies against Candida: potential therapeutics?

For many years, there has been controversy over the role of antibodies in immunity to Candida, but recently specific antibodies to mannoproteins and hsp90 have been shown to be protective against murine candidiasis. Combined with technical advances in antibody engineering, this raises the possibility of harnessing such antibodies into a new range of therapeutics.

Preliminary assessment of a human recombinant antibody fragment to hsp90 in murine invasive candidiasis

Seroconversion to hsp90 is associated with recovery from systemic candidiasis in humans, and a murine monoclonal antibody to this hsp90 antigen (LKVIRK epitope) was protective in mice. A human recombinant antibody to the same epitope was assessed in acute and chronic models of murine invasive candidiasis. Lethal intravenous challenge with fluconazole-susceptible (strain 4) or fluconazole-resistant (strain 019) Candida albicans, followed 2 h later by a single dose of recombinant antibody, was associated with a statistically significant drop in mortality of > or = 40% (two experiments in BALB/c mice given strain 4; one experiment in CD-1 mice given strain 019) or 23% (BALB/c mice, strain 019). In mice sublethally infected with strain 4, treatment with recombinant antibody was associated with improved renal clearance of infection. Antibody-mediated protection may involve neutralization of the protein-binding properties of circulating candidal hsp90, since LKVIRK strongly bound dexamethasone in vitro.

Controlled study of fluconazole in the prevention of fungal infections in neutropenic patients with haematological malignancies and bone marrow transplant recipients

The efficacy and safety of oral fluconazole versus a polyene regimen in preventing mycoses in neutropenic patients was compared. Patients with haematological malignancy or bone marrow transplantation received as antifungal prophylaxis either fluconazole 200 mg daily or a regimen consisting of clotrimazole trouches 10 mg twice daily with mycostatin, 500,000 I.U. four times daily, benadryl and cepacol mouthwash. Ninety patients at risk for fungus infection were evaluable. Four of 42 patients (9.5%; confidence interval 2%-23%) on fluconazole and 17 of 48 patients (35.4%; confidence interval 22%-52%) (p < 0.01) on the clotrimazole regimen developed a clinically significant fungal infection, including 3 (7.1%) and 11 (22.9%) patients respectively who had severe fungal infection, mainly pulmonary aspergillosis. Death directly due to a fungal infection within 100 days of the start of prophylaxis occurred in 2 of 42 patients (4.8%) and 9 of 48 patients (18.8%) respectively (p < 0.06). Kaplan-Meier analysis showed that the chance of survival on fluconazole was statistically greater than for the clotrimazole regimen (p < 0.04). A decrease of candidal colonisation of the gastrointestinal and genitourinary tracts occurred only in patients receiving fluconazole. No significant toxicity occurred. A 200 mg daily dose of fluconazole given to these patients thus appears to be well tolerated and to provide a protective effect against the development of fungal infection and death from severe fungal disease.

Comparison of PCR fingerprinting, by random amplification of polymorphic DNA, with other molecular typing methods for Candida albicans

Fingerprinting by random amplification of polymorphic DNA (RAPD) was compared with existing molecular typing systems for Candida albicans. Fifteen isolates were chosen, including three from the same patient; these gave 14 distinct karyotypes by pulsed-field gel electrophoresis (PFGE) and 7 different DNA types by EcoRI-generated restriction fragment length polymorphisms (RFLPs). RAPD with primer I (5'GCTGGTGG3') gave 5 types, whereas primer II (5'GCGCACGG3') yielded 11 types. Combining the results from both primers, all isolates were unique by RAPD with the exception of the three from the same patient. RAPD provided a fast, economical and reproducible means of typing C. albicans with a level of discrimination approaching that of PFGE.

The role of hsp90 in fungal infection

The immunodominant antigens of many microbial pathogens are heat shock proteins (hsps). In systemic candidal infections, a major target of protective antibody is an epitope shared with human hsp90. Here, Ruth Matthews and James Burnie suggest that fungal hsp90 plays a key pathogenic role in systemic infection by either binding to certain serum proteins, causing them to malfunction, or by mimicking the functional activity of other proteins.

Identification of a gene encoding an HPr-like protein in Aspergillus fumigatus

The gene encoding a histidine-containing protein (HPr)-like protein was identified in a cDNA library of Aspergillus fumigatus. The predicted amino acid sequence of the fungal HPr showed greater homology with HPr from Gram-positive bacteria than from Gram-negative bacteria. Since other components of the phosphoenolpyruvate: carbohydrate phosphotransferase system have not been identified in eukaryotes, this raises the question of what regulatory function the HPr-like protein might have evolved in this fungus.

Cloning of a DNA sequence encoding a major fragment of the 47 kilodalton stress protein homologue of Candida albicans

Part of the gene coding for the immunodominant 47 kDa antigen of the human fungal pathogen Candida albicans was cloned and sequenced. The predicted amino acid sequence was homologous to stress proteins, the most extensive similarity being with the heat shock protein hsp 90 of Saccharomyces cerevisiae. The 47 kDa antigen has diagnostic and therapeutic potential and is the first candidal antigen to be cloned and sequenced.

Assessment of DNA fingerprinting for rapid identification of outbreaks of systemic candidiasis

DNA fingerprinting was assessed as an improved typing system for Candida albicans aimed at speeding the implementation of cross infection control measures in outbreaks of systemic candidiasis. The study was carried out with 45 previously characterised isolates from five different outbreaks and with 96 unrelated isolates from a mixed control population. Sixteen different genotypes were produced. Results were obtainable within days, reproducibility was high, and there was good discrimination among different outbreaks. Compared with existing typing systems DNA fingerprinting provides a robust system that may be used rapidly to identify outbreaks of nosocomial candidiasis in laboratories with no specialist skill in typing C albicans.

Candida and AIDS: evidence for protective antibody

Clinical observation and animal models of candidosis suggest that, although T lymphocytes are important in preventing superficial candidosis, defence against systemic candidosis depends upon humoral immunity. An antibody response to the immunodominant 47 kD antigen of Candida albicans is invariably associated with recovery. The presence of this antibody in patients with chronic mucocutaneous candidosis and the acquired immunodeficiency syndrome (AIDS) could account for the rarity of disseminated candidal infection in these conditions. Polyclonal B cell activation may be responsible for the frequency with which this antibody is produced in AIDS. Antibody to the 47 kD antigen could be useful in the treatment and prevention of systemic candidosis, though not in the superficial candidosis of AIDS.

Diagnosis of systemic candidiasis by an enzyme-linked dot immunobinding assay for a circulating immunodominant 47-kilodalton antigen

A dot immunobinding assay based on the detection of the immunodominant 47-kilodalton (kDa) antigen of Candida albicans is described for the serological diagnosis of systemic candidiasis. It was compared with a reverse passive latex agglutination test and a dot immunobinding assay with total unfractionated hyperimmune serum to C. albicans. Use of the 47-kDa antigen-specific probe increased both the sensitivity and specificity of the assay system. Patients with systemic candidiasis were detected earlier in the course of the infection. The rate of detection of systemic C. albicans infections in neutropenic patients was 77% compared with 55% with total antibody in the dot immunobinding assay and 29% with the latex test. All three assay systems were positive in over 73% of infected patients who were not neutropenic. The 47-kDa antigen-specific probe was relatively specific to C. albicans. Antibody probes to the immunodominant antigens of other yeasts might be incorporated in the same dot immunobinding assay to detect systemic candidiasis caused by other species of yeasts.

Immunoblot analysis: a new method for fingerprinting hospital pathogens

Immunoblotting has recently become popular as a way of fingerprinting those hospital pathogens where other more conventional typing systems are deficient. Extracts of microorganisms are prepared by chemical or enzymic means, run on a standard SDS-PAGE gel and transferred onto nitrocellulose membrane. They are then probed either by a hyperimmune antiserum raised in a rabbit or by serum from a patient who has been previously infected by the organism. The pattern of antigenic bands which stain forms the basis of the method. This article discusses the limitations of the system, makes recommendations for further systems and outlines a typical fingerprinting protocol.

Factors affecting selected reciprocal muscle group ratios in preadolescents

This study examines the influence of limb velocity and lateral dominance on the relationship between the knee flexors and extensors. Thirty preadolescents, 18 male and 12 female, performed a series of reciprocal knee flexion-extension movements on the Cybex II isokinetic system. The tests were performed at a range of selected velocities and on both dominant and nondominant limbs. The agonist-antagonist ratios considered were the peak torque ratios, the torque ratio produced at specific angles, and the ratio comparing the total work performed by the hamstrings with that of the quadriceps. The results showed that an increased limb velocity produces a significant increase in the peak torque and work ratios (P less than 0.05), limb velocity has no significant effect on the torque ratio produced at 30 degrees and 60 degrees in the preadolescents, and lower limb lateral dominance has no significant effect on the three ratios examined.

Fingerprinting Candida albicans

A new method of typing Candida albicans based on immunoblotting is described. Isolates were disrupted by a mixture of enzymic pretreatment with alpha-mannosidase followed by sonication. They were then stained using a modified ELISA system by a rabbit hyperimmune serum raised against a single isolate, C. albicans NCTC 3153. The 190 isolates examined from the London Hospital produced 16 different types. Type 1 accounted for 43% of the isolates and was the commonest type outside the intensive care unit. Type 2 caused an outbreak of systemic candidosis on the intensive care unit. The technique was much more sensitive than the serotyping and morphotyping methods and lacked the phenotypic variability of the biotyping procedure previously used to define the outbreak. The gel-to-gel variation precludes its use in large scale epidemiological work. Its value lies in identification of outbreaks so that they can be controlled by the introduction of measures to prevent cross-infection.

Velocity characteristics of an hydraulic weight training system

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Isokinetic measurement in preadolescent males

Eighteen preadolescent males (mean age 11.4 +/- 0.59 years) performed 15 knee flexion-extension repetitions on both legs. Peak torque (T peak) and torque acceleration energy (TAE) were measured using the Cybex II Isokinetic system, which permitted a study of the effect of limb velocity on T peak, TAE, and reciprocal muscle group ratios. The effect of limb dominance was also assessed. The results indicated (Student's t test) that an increase in limb velocity from 1.05 rad/s to 4.2 rad/s produced a significant decrease in the T peak generated (P less than 0.001). A similar increase in limb velocity resulted in a significant increase in the TAE recorded (P less than 0.001). The limb velocity was also shown to influence the T peak and TAE ratios in reciprocal muscle groups. At a limb velocity 1.05 rad/s mean T peak ratios of 0.64 and 0.66 were recorded for the dominant and nondominant limbs, respectively. At 4.2 rad/s, ratios recorded for dominant and non-dominant limbs were 0.79 and 0.80, respectively. The limb velocity of 1.05 rad/s produced TAE ratios of 0.21 (dominant) and 0.14 (nondominant), and at 4.2 rad/s, ratios of 0.28 and 0.24 were recorded for dominant and non-dominant limbs, respectively. No significant difference (P less than 0.001) was observed between T peak and TAE values recorded for the dominant and non-dominant limbs under the same conditions. These results indicate that young boys show velocity-related isokinetic strength characteristics similar to adults. Although they have lower absolute levels, the children showed typical adult reciprocal muscle group ratios. Limb dominance at this age is not reflected in strength differences.

A reverse passive latex agglutination test for the diagnosis of systemic candidosis

A new reverse passive latex agglutination test for the detection of serum antigen in systemic Candida albicans infection is reported. 1700 sera were examined from 91 patients who had either proven or suspected systemic candidosis, 183 patients who were colonized and 636 patients with no evidence of candidal infection. Thirty of the systemically infected patients had lymphoproliferative disorders and the rest a variety of surgical or medical diseases with no underlying neutropenia. The latex particles were sensitised with an antiserum raised in rabbits against a pressate of Candida albicans. The degree of antigenaemia was proportional to the likelihood of invasive disease such that a diagnostic cut-off point of 1 in 8 produced a test for systemic candidosis with a sensitivity of 90% and specificity of 80.4% in patients with lymphoproliferative disorders. In the remaining medical and surgical patients a diagnostic cut-off point of 1 in 10 produced a test with a sensitivity of 96.7% and specificity of 98.8%. The patients with lymphoproliferative disorders tended to produce lower serum antigen levels. The sera were also assayed for antibody using latex particles sensitised with pressate.