Combined international external quality assessment results of medical laboratory performance and reporting of samples with known antimicrobial resistance

Background

Reporting on the presence of antimicrobial resistance is of considerable concern both for individual patient care and for understanding the underlying health status within the community at large. Antimicrobial resistance is solely dependent upon clinical laboratory detection and thus can be impacted upon by the quality and competence of medical laboratories. Proficiency testing or external quality assessment (PT/EQA) is the international standard for the direct measurement of medical laboratory performance on critical testing.

Methods

An international, intercontinental collaborative retrospective study of medical laboratory performance in antibiotic resistance was performed by the Microbiology Working Group (MWG) of the European Organisation for External Quality Assurance for Laboratory Medicine (EQALM) with particular examination of laboratory performance on the testing and reporting of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and carbapenem-resistant Enterobacteriaceae (CRE).

Results

The results of 1880 medical laboratories were compiled. Strictly accurate reporting of isolates as resistant occurred with MRSA 96.9%, with VRE 91.3% and with CRE 93.1% of the time. On the other hand, very major errors (reporting of false susceptibility) were observed with 2.2% of MRSA and 2.4% of VRE and 0.8% of CRE. Major errors (false resistance) were reported for vancomycin susceptibility testing for MRSA at a rate of 0.6%.

Conclusions

Depending on how clinical physicians read and understand microbiology susceptibility reports, proficient acceptable results were reported either between 91% and 94% of the time, or between 97% and 100%. While very major errors are infrequently reported, they were found in all regions and could potentially cause poor treatment decisions by clinicians. A collective analysis of multi-program PT/EQA information can provide valuable insights into the testing and reporting practices of medical laboratories.

Headache Characteristics in Children With Pseudotumor Cerebri Syndrome, Elevated Opening Pressure Without Papilledema, and Normal Opening Pressure: A Retrospective Cohort Study

BACKGROUND

Certain headache characteristics and associated symptoms are commonly attributed to increased intracranial pressure, but they have not been systematically studied among children in the context of revised diagnostic criteria for pseudotumor cerebri syndrome (PTCS).

METHODS

We performed a retrospective cohort study of patients treated for suspected or confirmed PTCS. Charts were reviewed for PTCS and headache diagnostic criteria and associated characteristics. Chi-squared or Fisher's exact tests were used to compare the frequency of headache characteristics between groups.

RESULTS

One hundred and twenty-seven individuals were identified: 61 had definite PTCS, 10 had probable PTCS, 31 had elevated opening pressure (OP) without papilledema, and 25 had normal OP without papilledema. Eleven children had no headache (6 with definite PTCS, 5 with probable PTCS). Headache pattern was episodic in 49% (95% CI: 34-64%) of those with definite PTCS, 18% (95% CI 6-37%) of those with elevated OP without papilledema, and 16% (5-36%) of those with normal OP without papilledema. Headache location was more likely to involve the head along with neck or shoulders in those with definite PTCS compared with elevated OP without papilledema (OR = 7.2, 95% CI: 1.9-27.6) and normal OP (OR = 4.5, 95% CI: 1.3-15.6) groups.

DISCUSSION

While missing data and small cohort size are limitations, this study suggests that headache in PTCS is more likely to involve the head along with neck/shoulders, and that headache in PTCS may be episodic or constant. Headache is occasionally absent in PTCS.

Infections Caused by Actinomyces neuii: A Case Series and Review of an Unusual Bacterium

Background. Actinomyces neuii is a Gram-positive bacillus rarely implicated in human infections. However, its occurrence is being increasingly recognized with the use of improved identification systems. Objective. To analyse A. neuii infections in Alberta, Canada, and review the literature regarding this unusual pathogen. Methods. Cases of A. neuii were identified in 2013-2014 in Alberta. Samples were cultured aerobically and anaerobically. A predominant catalase positive Gram-positive coryneform bacillus with no branching was isolated in each case. Testing was initially done with API-CORYNE® (bioMérieux) and isolates were sent to the Provincial Laboratory for Public Health for further testing. Isolates' identities were confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry microbial identification system (MALDI-TOF MS MIS; bioMérieux) and/or DNA sequencing. Results. Six cases of A. neuii infection were identified. All patients had soft tissue infections; typically, incision and drainage were done followed by a course of antibiotics. Agents used included cephalexin, ertapenem, ciprofloxacin, and clindamycin. All had favourable outcomes. Conclusions. While A. neuii is infrequently recognized, it can cause a diverse array of infections. Increased use of MALDI-TOF MS MIS is leading to increased detection; thus, understanding the pathogenicity of this bacterium and its typical susceptibility profile will aid clinical decision-making.

Ralstonia pickettiiBacteremia Associated With Pediatric Extracorporeal Membrane Oxygenation Therapy in a Canadian Hospital

We describe 2 pediatric patients withRalstonia pickettiibacteremia associated with extracorporeal membrane oxygenation (ECMO) therapy. Investigation revealed a common environmental source—the ECMO temperature-control units. We created guidelines for disinfecting these units that do not void the manufacturer's warranty and have prevented additional cases of bacteremia due to this organism.

In vitro efficacy of N-acetylcysteine on bacteria associated with chronic suppurative otitis media

Background

The safety and efficacy of Ciprodex® has been demonstrated for treatment of chronic suppurative otitis media (CSOM). However, symptoms fail to resolve in 9-15% of patients. The objective of this study is to evaluate the efficacy of N-acetylcysteine (NAC) on S. aureus, and planktonic and sessile (biofilm forming) P. aeruginosa in vitro using clinical isolates from patients with CSOM.

Methods

1) Stability was assessed using liquid chromatography-mass spectrometry for each component in a prepared mixture of Ciprodex® and NAC over 15 days. Sterility was assessed by measuring bacterial growth on a blood agar plate. Efficacy was assessed using a disc diffusion method by inoculating plates with S. aureus ATCC 29513 and P. aeruginosa ATCC 27853, and measuring the clearance zone.

2) Fifteen P. aeruginosa strains were isolated from patients with CSOM and tested in vitro using the bioFILM PA™ antimicrobial susceptibility assay. Treatment solutions included Ciprodex® & ciprofloxacin +/- NAC, and NAC alone (0.25%, 0.5% & 1.25%).

Results

1) NAC combined with Ciprodex® demonstrated stability, sterility, and efficacy over a two-week period

2) P. aeruginosa strains in the sessile (33%-40%) and planktonic (13%) state demonstrated resistance to Ciprodex® and ciprofloxacin. When NAC ≥0.5% was used in isolation or as an adjunct to either of these medications, no resistance was found in the sessile or planktonic state among all 15 strains.

Conclusion

1) Ciprodex® combined with NAC has a shelf life of at least two weeks given the documented preservation of stability, sterility, and clinical efficacy of the mixed compounds.

2) P. aeruginosa strains demonstrated resistance to both Ciprodex® and ciprofloxacin. NAC ≥0.5% overcomes issues with resistance and shows promise in the treatment of CSOM.

The management of upper respiratory tract infections

Upper respiratory tract infections (URTIs), generally termed colds, sore throats and coughs, are common presentations in primary care. This article discusses the clinical picture, management, significant differential diagnosis, and specifically, when antibiotics may be required for an URTI.

Design of a Candida albicans disaccharide conjugate vaccine by reverse engineering a protective monoclonal antibody

A disaccharide-chicken serum albumin conjugate vaccine against Candida albicans infections has been developed by reverse engineering a protective monoclonal antibody, C3.1. The binding site of C3.1 binds short oligosaccharides of β1,2-linked mannopyranose residues present in the fungal cell wall phosphomannan. By delineating the fine detail of the molecular recognition of the cell wall β-mannan antigen, a disaccharide epitope was deduced to be the minimum size epitope that should induce the formation of protective antibody. Sequential functional group replacement of disaccharide hydroxyl groups to yield a series of monodeoxy and mono-O-methyl β1,2-linked mannobioside congeners established that three hydroxyl groups are essential for binding. Two of these, O-3 and O-4, are located on the internal mannose residue of the disaccharide, and a third, O-3', is located on the terminal mannose. Synthesis of a series of trisaccharides that mandate binding of either the reducing or nonreducing disaccharide epitopes provided the final indication that a disaccharide protein conjugate should have the potential to induce protective antibody. When disaccharide was conjugated to chicken serum albumin this vaccine produced antibodies in rabbits that recognized the native cell wall phosphomannan. In proof of concept protection experiments, three immunized rabbits showed a reduction in fungal burden when challenged with live C. albicans.

Prevalence of antimicrobial resistant pathogens from blood cultures from Canadian hospitals: results of the CANWARD 2007-2009 study

This study assessed the epidemiology and antimicrobial resistance of pathogens associated with bloodstream infections in Canadian hospitals between 2007 and 2009. Tertiary-care medical centers representing 8 of 10 Canadian provinces submitted bloodstream infection pathogens from patients attending hospital clinics, emergency rooms, medical/surgical wards, and intensive care units. Over 8,000 blood culture pathogens were collected. The 10 most common pathogens (representing 80.9% of all isolates) were Escherichia coli (1856 [22.6%]), Staphylococcus aureus (1457 [17.7%] including 1101 methicillin-susceptible Staphylococcus aureus and 356 methicillin-resistant Staphylococcus aureus), coagulase-negative staphylococci (907 [11.0%]), Klebsiella pneumoniae (600 [7.3%]), Streptococcus pneumoniae (470 [5.7%]), Enterococcus faecalis (360 [4.4%]), Pseudomonas aeruginosa (333 [4.0%]), viridans group streptococci (321 [3.9%]), Enterobacter cloacae (193 [2.3%]), and Streptococcus pyogenes (159 [1.9%]). The most active agents against Gram-negative bacilli were carbapenems (e.g., meropenem and ertapenem) and piperacillin-tazobactam, while for Gram-positive cocci, they were vancomycin, linezolid, and daptomycin.

Three swipes and you're out: how many swipes are needed to decontaminate plastic with disposable wipes?

At our hospital, health care workers use commercially available wipes to reduce bacterial counts on plastic surfaces. The workers use the wipes in a cursory fashion--swiping objects once for one to two seconds. We sought to measure the ability of wipes to reduce bacterial counts when swiped across plastic surfaces using various routines.

Bacterial contamination of health care workers' pagers and the efficacy of various disinfecting agents

Health care workers in our facility were surveyed, and their pagers were cultured before and after disinfection with various agents. All pagers were contaminated with bacteria, including the pathogens Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella spp. and methicillin-resistant S. aureus. Disinfection reduced bacterial contamination. No risk factors for pager contamination with pathogens were identified.

Interlaboratory study of quality control isolates for a broth microdilution method (modified CLSI M38-A) for testing susceptibilities of dermatophytes to antifungals

The Clinical and Laboratory Standards Institute (CLSI; formerly National Committee for Clinical Laboratory Standards, or NCCLS) M38-A standard for the susceptibility testing of filamentous fungi does not specifically address the testing of dermatophytes. In 2003, a multicenter study investigated the reproducibility of the microdilution method developed at the Center for Medical Mycology, Cleveland, Ohio, for testing the susceptibility of dermatophytes. Data from that study supported the introduction of this method for testing dermatophytes in the future version of the CLSI M38-A standard. In order for the method to be accepted by CLSI, appropriate quality control isolates needed to be identified. To that end, an interlaboratory study, involving the original six laboratories plus two additional sites, was conducted to evaluate potential candidates for quality control isolates. These candidate strains included five Trichophyton rubrum strains known to have elevated MICs to terbinafine and five Trichophyton mentagrophytes strains. Antifungal agents tested included ciclopirox, fluconazole, griseofulvin, itraconazole, posaconazole, terbinafine, and voriconazole. Based on the data generated, two quality control isolates, one T. rubrum isolate and one T. mentagrophytes isolate, were identified and submitted to the American Type Culture Collection (ATCC) for inclusion as reference strains. Ranges encompassing 95.2 to 97.9% of all data points for all seven drugs were established.

Histoplasmosis cluster, golf course, Canada

We report a cluster of 4 cases of acute histoplasmosis (1 culture proven and 3 with positive serology, of which 2 were symptomatic) associated with exposure to soil during a golf course renovation. Patients in western Canada with compatible symptoms should be tested for histoplasmosis, regardless of their travel or exposure history.

Routine antimicrobial susceptibility testing of coagulase-negative staphylococci isolated from blood cultures: is it necessary?

The clinical significance of discontinuing routine antibiotic susceptibility testing (AST) of coagulase-negative Staphylococcus (CNS) isolates from blood cultures was investigated. Prospectively, AST was requested primarily for patients with serious underlying illnesses. Antibiotic use did not change significantly when AST was not performed routinely. Laboratory cost savings were 75% if AST was not performed, but more specimens were submitted from these patients. Oxacillin resistance in coagulase-negative staphylococci from blood cultures has remained > 70% since implementation of this protocol, while annual vancomycin utilisation has shown only small, incremental increases. Therefore, it is suggested that routine AST of CNS isolates from blood culture is not essential.

Bacteriology of a bear bite wound to a human: case report

Human contact with bears has become more frequent, as has the resultant bear maulings and bite injuries. We report the bacteriology of a patient bitten by a grizzly bear (Ursus arctos) from the Rocky Mountains foothills area east of Banff National Park, Alberta, Canada. The patient received field care, including metronidazole and cefazolin. Subsequent deep-wound cultures grew Serratia fonticola, Serratia marcescens, Aeromonas hydrophila, Bacillus cereus, and Enterococcus durans but no anaerobes.

Quality control limits for voriconazole disk susceptibility tests on Mueller-Hinton agar with glucose and methylene blue

An international collaborative study was performed in order to propose quality control limits for voriconazole disk diffusion tests on Mueller-Hinton agar with 2% glucose and 0.5 micro g of methylene blue per ml. The supplement may be added to the agar before autoclaving, or Mueller-Hinton agar plates may be flooded with a glucose-methylene blue solution. Replicate tests on both types of agar plates with 1- micro g voriconazole disks generated data to propose zone size limits for tests of Candida parapsilosis ATCC 22019 (28 to 37 mm), Candida albicans ATCC 90028 (31 to 42 mm), and Candida krusei ATCC 6258 (16 to 25 mm). Candida tropicalis ATCC 750 was not useful for this purpose.

Development of a Standardized Susceptibility Test forCampylobacterwith Quality-Control Ranges for Ciprofloxacin, Doxycycline, Erythromycin, Gentamicin, and Meropenem

A standardized agar dilution susceptibility testing method was developed for Campylobacter that consisted of testing on Mueller-Hinton medium supplemented with 5% defibrinated sheep blood in an atmosphere of 10% CO2, 5% O2, and 85% N2. Campylobacter jejuni ATCC 33560 was identified as a quality-control (QC) strain. Minimal inhibitory concentration (MIC) QC ranges were determined for two incubation time/temperature combinations: 36 degrees C for 48 hr and 42 degrees C for 24 hr. Quality-control ranges were determined for ciprofloxacin, doxycycline, erythromycin, gentamicin, and meropenem. For all antimicrobial agents tested at both temperatures, 95-100% of the QC MIC results fell within recommended QC ranges. Twenty-one Campylobacter clinical isolates, encompassing five species of Campylobacter (C. jejuni, C. coli, C. jejuni, subsp. doylei, C. fetus, and C. lari) were tested in conjunction with the C. jejuni QC strain. While C. jejuni and C. coli could be reliably tested under both test conditions, growth of C. jejuni subsp. doylei, C. fetus, and C. lari isolates was inconsistent when incubated at 42 degrees C. Therefore, it is recommended that these species only be tested at 36 degrees C.

Pseudomonas infections in the thermally injured patient

Pseudomonas aeruginosa, remains a serious cause of infection and septic mortality in burn patients, particularly when nosocomially acquired. A prototypic burn patient who developed serious nosocomially acquired Pseudomonas infection is described as an index case which initiated investigations and measures taken to identify the source of the infection. The effect of changes in wound care to avoid further nosocomial infections was measured to provide data on outcome and cost of care. The bacteriology of Pseudomonas is reviewed to increase the burn care providers understanding of the behaviour of this very common and serious pathogen in the burn care setting, before reviewing the approach to detection of the organism and treatment both medically and surgically. After controlling the nosocomial spread of Pseudomonas in our burn unit, we investigated the morbidity and mortality associated with nosocomial infection with an aminoglycoside resistant Pseudomonas and the associated costs compared to a group of case-matched control patients with similar severity of burn injury, that did not acquire resistant Pseudomonas during hospitalization at our institution. We found a significant increase in the mortality rate in the Pseudomonas group compared to controls. The morbidity in terms of length of stay, ventilator days, number of surgical procedures, and the amount of blood products used were all significantly higher in the Pseudomonas group compared to controls. Costs associated with antibiotic requirements were also significantly higher in the Pseudomonas group. Despite this increased resource consumption necessary to treat Pseudomonas infections, these efforts did not prevent significantly higher mortality rates when compared to control patients who avoided infection with the resistant organism. Thus, in addition to the specific measures required to identify and treat nosocomial Pseudomonas infections in burn patients, prevention of infection through modification of treatment protocols together with continuous infection control measures to afford early identification and eradication of nosocomial Pseudomonas infection are critical for cost-effective, successful burn care.

Quality control limits for fluconazole disk susceptibility tests on Mueller-Hinton agar with glucose and methylene blue

An international collaborative study was performed in order to propose quality control limits for fluconazole disk diffusion susceptibility tests on Mueller-Hinton agar with 2% glucose and 0.5 micro g of methylene blue per ml. The supplements may be added before autoclaving the agar, or Mueller-Hinton agar plates may be flooded with a glucose-methylene blue solution. Replicate tests on both types of agar plates generated data to propose zone size limits for tests of Candida parapsilosis ATCC 22019 (22 to 33 mm), C. tropicalis ATCC 750 (26 to 37 mm), and C. albicans ATCC 90028 (28 to 39 mm). C. krusei ATCC 6258 was not useful for this purpose.

Sputum isolation of Wangiella dermatitidis in patients with cystic fibrosis

We report a case of invasive fungal pulmonary infection in a cystic fibrosis patient. Clinical deterioration coincided with isolation of Wangiella dermatitidis from her sputum, and treatment with amphotericin B followed by voriconazole resulted in clinical improvement and sterilization of the sputum. This case suggests that W. dermatitidis may be an etiologic agent of invasive pulmonary disease in the cystic fibrosis population.

Characterization of Pseudomonas aeruginosa isolates: occurrence rates, antimicrobial susceptibility patterns, and molecular typing in the global SENTRY Antimicrobial Surveillance Program, 1997-1999

During 1997-1999, a total of 70,067 isolates (6631 Pseudomonas aeruginosa isolates) were analyzed in the SENTRY program by geographic region and body site of infection. The respiratory tract was the most common source of P. aeruginosa. P. aeruginosa isolation rates increased during the study interval. Europe was the only region to show a significant decline in beta-lactam and aminoglycoside susceptibility rates. There was a reduction in the rates of susceptibility of Canadian isolates to imipenem and of Latin American isolates to meropenem. A total of 218 multidrug-resistant P. aeruginosa isolates (MDR-PSA; resistant to piperacillin, ceftazidime, imipenem, and gentamicin) were observed; MDR-PSA occurrence rates (percentages of all isolates) ranged from 8.2% (Latin America) to 0.9% (Canada). No antimicrobial inhibited >50% of MDR-PSA strains. Molecular characterization of selected, generally resistant strains was performed. Isolates showing unique ribogroups were found in Europe, Latin America, and the United States, but clonal spread was documented in several medical centers.

Acute vaginal candidosis model in the immunocompromized rat to evaluate delivery systems for antimycotics

A rat model of vaginal candidosis, suitable for screening new antifungal compounds or novel formulations was developed and validated. Two strains of Candida albicans, different inoculation schedules, quantitative assays for fungal burden and the necessity for immunosuppression were tested. The infection was evaluated clinically and histologically by fungal counts from the vaginal discharge. The animals without immunosuppression did not sustain the infection beyond 2-3 days, however, after immunosuppression with cyclophosphamide, the infection can be maintained for about 2 weeks and is suitable for the testing of topical antifungal therapies.

Serological evidence of increased Coccidioides immitis infections in western Canada in 1996

OBJECTIVE

To investigate the epidemiology of Coccidioides immitis infection in persons returning to western Canada from C immitis endemic zones in southwestern United States.

DESIGN

Review of C immitis serology requests from 1996.

METHODS

Data were based on review of enzyme immunoassay and immunodiffusion results from 1993 to 1996 inclusive. Detailed information on clinical presentation, treatment and outcome of disease process was obtained through questionnaires and interviews with physicians who submitted Coccidioides serology requests in 1996.

RESULTS

Positive serology for C immitis increased from 4.7% to 5.2% (between 1993 and 1995 inclusive) to 10.7% in 1996. Enzyme immunoassay for immunoglobulin G and/or immunoglobulin M or immunodiffusion was positive in 25 patients in 1996. The mean age of these patients was 62 years, and the predominant clinical presentation was pulmonary infiltrate with fever. All patients with positive serology were known to have travelled to central or southwestern Arizona or southern California.

CONCLUSIONS

Travel to a defined coccidioidomycosis endemic zone presents a risk for the older traveller. Serology for C immitis supported the clinical, histological and microbiological diagnoses in patients who had travelled to this defined endemic zone.

Clinical evaluation of the ASTY colorimetric microdilution panel for antifungal susceptibility testing

A method using a commercially prepared colorimetric microdilution panel (ASTY; Kyokuto Pharmaceutical Industrial Co., Ltd.) was compared in four different laboratories with the National Committee for Clinical Laboratory Standards (NCCLS) reference microdilution method by testing 802 clinical isolates of Candida spp. (C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. krusei, C. lusitaniae, C. guilliermondii, C. lipolytica, C. rugosa, and C. zeylanoides) against amphotericin B, 5-fluorocytosine (5FC), fluconazole, and itraconazole. Reference MIC endpoints were established after 48 h of incubation, and ASTY endpoints were established after 24 and 48 h of incubation. ASTY endpoints were determined to be the time at which the color of the first well changed from red (indicating growth) to purple (indicating growth inhibition) or blue (indicating no growth). Excellent agreement (within 2 dilutions) between the reference and colorimetric MICs was observed. Overall agreement was 93% at 24 h and 96% at 48 h. Agreement ranged from 90% with itraconazole and 5FC to 96% with amphotericin B at 24 h and from 92% with itraconazole to 99% with amphotericin B and 5FC at 48 h. The ASTY colorimetric microdilution panel method appears to be comparable to the NCCLS reference method for testing the susceptibilities of Candida spp. to a variety of antifungal agents.

Release of Candida albicans yeast antigens upon interaction with human neutrophils in vitro

Candida albicans is the leading cause of invasive candidosis. As conventional tests do not reliably detect invasive infection, attention has turned to the detection of C. albicans antigens circulating in blood. As antigen tests for invasive candidosis could be improved if C. albicans antigens released upon phagocytosis were defined, this study was undertaken to characterise antigens released during the interaction of yeasts and human neutrophils in vitro. An enzyme immunoassay developed previously to detect what were believed to be predominantly C. albicans cytoplasmic antigens in patients with invasive candidosis was used to follow the neutrophil-mediated release of yeast antigens. Serum opsonisation enhanced antigen release, which was rapid and essentially complete by 1 h. When fresh C. albicans yeasts were added to medium from cultures of neutrophils plus yeasts or neutrophils plus latex beads, additional yeast antigens were released. Medium from neutrophils plus yeasts or from yeasts alone had similar immunoblot patterns with rabbit antibodies to a C. albicans cytoplasmic antigen preparation, with the reactive antigens generally being of higher mol. wt than the reactive antigens in the antigen mixture used for preparation of the antiserum. The two supernates also had similar immunoblot patterns with rabbit anti-C. albicans cell-wall mannan antibodies. These results suggest that yeast surface antigens are released quickly during phagocytosis by neutrophils. Detection of such yeast surface antigens, possibly together with selected yeast cytoplasmic antigens, should improve the sensitivity of C. albicans antigen assays.

A single strain of Candida albicans associated with separate episodes of fungemia and meningitis

Four isolates of Candida albicans recovered from the blood and cerebral spinal fluid of a 66-year-old man during episodes of systemic infection separated by 3 months and antifungal therapy were analyzed by a variety of molecular typing methods. All four isolates were shown to represent the same strain, indicating a relapse of infection rather than reinfection.

Evaluation of enzyme immunoassay for Candida cytoplasmic antigens in neutropenic cancer patients

A Candida albicans cytoplasmic antigen enzyme immunoassay (CACP antigen EIA) was developed with antibodies raised against antigens prepared from yeast cells grown under standardized growth conditions. The C. albicans components reactive in the EIA were shown to be predominantly proteins with associated carbohydrates. Denaturing gel electrophoresis revealed the presence of five major CACP proteins with molecular weights between 36,000 and 44,000. The clinical usefulness of the CACP EIA was evaluated by retrospective blinded measurement of 89 serum samples from 31 granulocytopenic patient episodes. Twice-weekly surveillance cultures, sequential serum samples (approximately once per week or with change of the clinical course), and standard diagnostic criteria of fungal infection were used to categorize patients. The sensitivity and specificity of the CACP assay on the basis of serum samples were 82 and 100%, respectively (67 and 100% on the basis of patient episodes). The positive and negative predictive values were 100 and 97% for serum (100 and 93% for patient episodes). By comparison, the CANDTEC assay had low sensitivity (33%) and poor positive predictive values (50%). The CACP EIA may be a useful test suitable for further evaluations as a method for the diagnosis of invasive Candida infection in neutropenic cancer patients.

Laboratory and clinical evaluations of media for the primary isolation of Haemophilus species

There has not previously been an objective comparison of medium formulations for the primary isolation of Haemophilus species. This study was undertaken to evaluate the components required for the optimal growth of large, easily identifiable colonies of these bacteria. We compared six medium bases and seven supplements for their ability to support the growth of 86 strains of Haemophilus influenzae and 17 strains of other species of Haemophilus. By using a growth index that combines colony size and the dilution factor, a formulation of GC agar base with 1% yeast autolysate and 5% sheep blood (chocolated) promoted the growth of large, easily recognizable colonies of H. influenzae and other Haemophilus species. This medium was designated GCYSB. The addition of hematin to supplements that supplied NAD (or factor V) to the medium was inhibitory to the growth of all of the Haemophilus species tested. In a clinical comparison of GCYSB with routinely used chocolate agar medium in two laboratories for the primary isolation of Haemophilus species, overall GCYSB promoted better growth of 124 strains of H. influenzae and H. parainfluenzae. GCYSB is easy to prepare and inexpensive compared with the ease of preparation and expense of other Haemophilus isolation media.

Disseminated candidiasis due to amphotericin B-resistant Candida albicans

Although development of resistance in Candida albicans to amphotericin B is considered rare, C. albicans was persistently recovered from a 28-year-old man after a prolonged course of broad-spectrum antimicrobial therapy for a pancreatic abscess. Determination of the MICs of drugs for C. albicans in Sabouraud broth revealed MICs of 2.5 mg/l amphotericin B, greater than 40 mg/l ketoconazole, 2.5 mg/l miconazole, and greater than 40 mg/l 5-fluorocytosine. Synergy testing revealed a MIC of 0.3 mg/l amphotericin B in the presence of 2.5 mg/l 5-fluorocytosine. When intravenous 5-fluorocytosine was added to the patient's antifungal regimen, achieving levels of 125 mg/l, negative blood cultures resulted for the first time. This suggests there may be a clinical use for in vitro synergy testing as an adjunct to guide antifungal therapy for fungemia due to amphotericin B-resistant C. albicans.

Neonatal Campylobacter fetus meningitis: a report of an unusual case

Campylobacter fetus is a rare cause of meningitis in the pediatric age group and, in particular, among neonates. The clinical presentation of campylobacter meningitis in high-risk neonates is not well-described. A review of campylobacter meningitis by Lee et al in 1985 reported nine cases occurring in neonates, of which only one case was caused by C. fetus. In the ensuing six years only three more confirmed cases of neonatal meningitis caused by C. fetus have been reported. We here report another confirmed case of C. fetus meningitis in a neonate.

Data collection and analysis from a respiratory inductance plethysmograph

A respiratory inductance plethysmograph, Respitrace, was used to assess the respiratory effects of narcotic analgesia for the first 24 hours after surgery. Data were collected on-line from the plethysmograph with an Apple][+ microcomputer and stored on disc for later analysis of respiratory rates and tidal volumes, and also periods of central or obstructive apnoea using the difference in phase angle between the abdominal and respiratory components. This involved the measurement of, on average, more than 20,000 breaths per patient and techniques of data compression were required to store this amount of information on a single floppy disc. Frequent nursing interventions reduced the accuracy of tidal volume and phase angle measurements, but respiratory rates were obtained accurately breath by breath.

Computer control of a Braun Infusomat pump

Machine code programs have been produced to allow a simple method of communication between a computer and the Braun Infusomat pump. Commands are set up as character strings using a high-level language and passed to a machine code program which transmits them to the pump. Messages from the pump are received under interrupt control for display by the high-level language. Any error in communication is stored in memory and the appropriate action taken by the main application program.

Microcomputer-based haemodynamic monitoring during continuous extradural analgesia

A system for monitoring, recording and storing arterial pressure and heart rate during continuous extradural analgesia has been developed using an Apple II microcomputer and a Dinamap 1846 non-invasive arterial pressure monitor. The administration of local anaesthetic (or vasopressor) was recorded using a light pen. The computer was programmed to recognize this, and to initiate automatically more frequent measurements of heart rate and arterial pressure. The results of a study using this equipment are reported. The commands for computer control of the Dinamap 1846 are described.

Computer control of an Imed 929 infusion pump

There is a growing interest in the potential benefits to be obtained from closed-loop control of drug infusion [1-5]. The most widely available infusion pump which is specifically designed for control by computer is the 929 volumetric infusion pump produced by Imed. The increasing availability of microcomputers suggests that they will be used more frequently to control such pumps. However, difficulties can arise when the attempt is made to establish communication between the computer and the pump [6] and a method employed for this purpose is described in this article. The aim was to provide a simple method of conducting the required communication between the computer and the pump using a high-level language. The commands specified in the high-level language are passed to a machine-code subroutine which organizes transmission to and receives data from the pump.