Vivax malaria detection using a parasitic red blood cell flag generated by the Sysmex XN-9000 hematology analyzer

INTRODUCTION

A Sysmex XN-series hematology analyzer (Sysmex), the next generation up from the Sysmex XE-series, can provide information regarding malaria infection in the form of a parasitic red blood cell (pRBC) flag. This study aimed to determine the usefulness of the pRBC flag for early detection and follow-up in patients infected with Plasmodium vivax.

METHODS

A total of 221 patients with fever for whom CBC and malaria microscopy had been requested were analyzed. Sixty-seven individuals were diagnosed with P vivax infection, and 154 were diagnosed with other febrile diseases. The sensitivity and specificity of the pRBC flag for malaria parasite detection and the relationship between parasite density and presence of the pRBC flag were determined. The concordance rate between malaria microscopy and pRBC flag in 147 follow-up cases was calculated.

RESULTS

The pRBC flag was detected in 56 of 67 malaria patients (sensitivity, 83.6%; specificity, 100%). The patients with the pRBC flag at initial diagnosis revealed significantly higher parasite density than the patients without the pRBC flag (P < .05). The concordance rate between malaria microscopy and pRBC flag in the follow-up cases was 53.1%.

CONCLUSION

Considering its high sensitivity in malaria-suspicious patients, unexpected vivax malaria cases can be detected with the pRBC flag when CBC is done in a routine laboratory setting. The pRBC flag provided by the Sysmex XN series is a valuable tool for vivax malaria detection.

A case of fixed drug eruption due to doxycycline and erythromycin present in food

A fixed drug eruption (FDE) is not difficult to diagnose, given its clinical characteristics. However, the causative agent can be difficult to identify, particularly when the patient denies ingestion of any drugs. To the best of our knowledge, we present herein the first reported case of an FDE caused by antibiotics taken in food; doxycycline and erythromycin contained in pork and fish. A 57-year-old female experienced repeated episodes of well-demarcated erythematous patches covering her entire body. She denied taking any medications, but she thought that the lesions appeared after consuming pork and/or fish. An oral provocation test showed positive results for doxycycline and erythromycin, commonly used antibiotics in live-stock farming and in the fishing industry. Because of the antibiotics' thermostability, cooking does not guarantee the elimination of residual drugs. From the patient's history, we concluded that doxycycline and erythromycin contained in the pork and fish that she ate were the cause of the FDE.

Microscopic schistocyte determination according to International Council for Standardization in Hematology recommendations in various diseases

INTRODUCTION

Recently, a consensus report for microscopic schistocyte determination was prepared by International Council for Standardization in Hematology (ICSH). ICSH focused on diagnosis of thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS). We aimed to reanalyze schistocytes according to ICSH recommendations, to study diseases other than TTP/HUS related to the schistocytes, and to compare the percentage of schistocytes among the various diseases.

METHODS

We retrieved all reported cases of peripheral blood (PB) smear in a single institution during 6 years. Schistocytes on 282 PB smears showing previous peripheral schistocytes and hemoglobin ≤10 g/dL were recounted according to ICSH recommendations.

RESULTS

The schistocytes were frequently observed in patients with microangiopathic hemolytic anemia (MAHA), metastatic carcinoma, sepsis, chronic renal failure, preterm infant, and infection. Only two among 34 patients categorized as MAHA were diagnosed as TTP/HUS. Schistocytes were observed with other morphological changes in 169 of 170 cases with schistocyte ≤1% and in 102 of 112 with schistocyte >1%. The median schistocyte percentages of patients with hematologic malignancy, megaloblastic anemia, acute renal failure, and preterm infant were 1.20%, 1.30%, 1.35%, and 1.70%, respectively.

CONCLUSION

Schistocytes were observed above 1% in many diseases other than TTP /HUS. Therefore, it is important to understand that schistocytes could be seen in various diseases, and in these cases, schistocytes were usually detected together with other red blood cell morphologic changes. These data support ICSH recommendation that a schistocyte count should be considered clinically meaningful if schistocytes represent the main morphological abnormality in the PB smear.

High levels of remnant lipoprotein cholesterol is a risk factor for large artery atherosclerotic stroke

BACKGROUND AND PURPOSE

Remnant lipoproteins (RLPs) are products of partially catabolized chylomicrons and very-low-density lipoprotein, from which some triglycerides have been removed. These particles are smaller and denser than the parent particles and are believed to be strongly atherogenic. We explored the association between RLP cholesterol (RLP-C) and ischemic stroke, including stroke subtypes.

METHODS

A cohort of 142 ischemic stroke patients (90 men and 52 women; age, 65.2±12.8 years, mean±SD) was enrolled; all had acute infarcts confirmed by diffusion-weighted MRI, and had fasting lipograms. A full stroke-related evaluation was conducted on each patient. An outpatient population of 88 subjects without a history of cerebrovascular or cardiovascular disease served as a control group. Serum RLP fractions were isolated using an immunoaffinity gel containing specific antiapolipoprotein (anti-apo)B-100 and anti-apoA-I antibodies. RLP-C values were considered to be high when they were in the highest quartile of all values in the study.

RESULTS

High RLP-C values were more common in stroke patients than in control patients (31.0% vs. 14.8%, p=0.01), when 5.6 mg/dL (>75th percentile) was used as the cutoff value. Multivariable analyses indicated that RLP-C was a risk factor for stroke, with an odds ratio of 2.54 (p=0.045). The RLP-C level was higher in the large artery atherosclerosis subgroup (5.7±3.9 mg/dL) than in any other stroke subgroup (small vessel occlusion, 4.9±5.9 mg/dL; cardioembolism, 1.8±2.3 mg/dL; stroke of undetermined etiology, 3.1±2.9 mg/dL).

CONCLUSIONS

We have found an association between high RLP-C levels and ischemic stroke, and in particular large artery atherosclerotic stroke.

[Current status and proposal of a guideline for manual slide review of automated complete blood cell count and white blood cell differential]

BACKGROUND

Manual slide review (MSR) is usually triggered by the results of automated hematology analyzers, but each laboratory has different criteria for MSR. This study was carried out to investigate the current status of MSR criteria of automated complete blood cell count (CBC) and white blood cell (WBC) differential results and to propose a basic guideline for MSR.

METHODS

Total 111 laboratories were surveyed regarding MSR using questionnaires. The questionnaire asked: kinds of automated hematology analyzers used and the presence of criteria triggering MSR in seven categories: 1) CBC results, 2) 5 differential WBC counts, 3) 3 differential WBC counts, 4) automated reticulocyte counts, 5) delta check, 6) instrument flags (or messages), 7) clinical information (wards or diseases). Based on the survey results, we determined basic and extended criteria for MSR. With these criteria, we consulted nine hematology experts to get a consensus.

RESULTS

All 111 laboratories had their own MSR criteria. Among 111 laboratories, 98 (88.3%) used more than three criteria for MSR including CBC results and 5-part WBC differential count results and 95 (85.6%) had criteria of flags triggering MSR. For MSR criteria with numeric values, the 10th, 50th, and 90th percentiles of upper and lower threshold values were obtained. The basic guideline for MSR was made.

CONCLUSIONS

We proposed a basic guideline for MSR. This guideline would be helpful to hematology laboratories for their daily operation and providing more rapid and accurate CBC and WBC differential results.

[Current status of external quality assessment of fecal occult blood test]

BACKGROUND

Nationwide external quality assessment (EQA) of the fecal occult blood test (FOBT) in Korea was first introduced in 2007-2009. The EQA results were analyzed to assess the current status of FOBT and to plan the continuation of the EQA program.

METHODS

The surveys included 40 hospitals in the preliminary survey conducted in 2007, 249 general hospitals in 2008, and 389 hospitals in 2009. In the surveys, the participating hospitals provided the results of the distributed materials and replies to the questionnaire on the FOBT test procedures and quality controls.

RESULTS

In the surveys conducted between 2007 and 2009, a total of 650 institutes submitted 653 test system results; 3 institutes used 2 kinds of methods. All of the institutes used immunologic methods; 107 institutes (16.5%) used quantitative equipments and 546 institutes (84.0%) used qualitative kits. Most quantitative tests yielded consistent positive or negative results; however, their cut-off and measured values differed according to the equipments used. A low-level material tested in 2007 was negative in the quantitative methods but positive in some qualitative methods because of lower detection limits. The discordance rates among quantitative tests were 3.2% in 2007, 4.4% in 2008, and 0% in 2009 and the rates among qualitative tests were 13.8% in 2008 and 2.6% in 2009. Semi-solid EQA materials showed the ability to evaluate the overall test procedures with acceptable stability.

CONCLUSIONS

In the first Korean FOBT EQA, commercially available EQA materials were proven to be stable. Continuation of the EQA program and further education of laboratory personnel are needed to reduce inconsistency in results. Further, the test kit, procedures, and result reports must be standardized.

[Effectiveness of sodium fluoride as a glycolysis inhibitor on blood glucose measurement: comparison of blood glucose using specimens from the Korea National Health and Nutrition Examination survey]

BACKGROUND

Accurate measurement of blood glucose concentrations is essential for defining diabetes, and the minimization of ex vivo glycolysis has been recommended. Recent guidelines advocate two kinds of methods for sample collection and processing: either the sodium fluoride (NaF) method or immediate refrigeration using a serum separation tube (SST). We investigated the difference between the two methods in measuring subsequent glucose concentrations using blood specimens from participants recruited for the fourth Korean National Health and Nutrition Examination Survey.

METHODS

Paired venous blood samples were collected in an SST and a NaF tube from 1,103 men and women. SST serum was separated within 30 min, including standing for 15 min, and then refrigerated. The NaF samples were refrigerated, but not separated until immediately before analysis. We compared the blood glucose concentrations between the SST (SST glucose) and NaF (NaF glucose) methods.

RESULTS

The mean SST glucose was significantly higher than NaF glucose (99.0 mg/dL vs 96.5 mg/dL, P<0.05). NaF glucose showed a negative mean bias of 2.6 mg/dL vs SST glucose but showed high correlation (R=0.9899). There was no significant correlation between the bias of blood glucose concentrations by two methods and the storage time of NaF glucose.

CONCLUSIONS

The negative bias associated with the use of NaF tubes may significantly affect the prevalence of diabetes. Serum separation and refrigeration within 30 min after venous sampling is recommended over NaF method, not only to minimize the preanalytical impact on detecting diabetes but also to reduce sample volume and number of tubes.

The implementation and effects of a clinical laboratory accreditation program in Korea from 1999 to 2006

BACKGROUND

The Korean Laboratory Accreditation Program (KLAP) by the Korean Society of Laboratory Medicine (KSLM) was started in 1999. We summarized history and achievement of KLAP for the last 8 yr.

METHODS

We analyzed 8 yr data (1999-2006) of historical events, trends of participating laboratories, and scores according to the impact of the question to the outcome of the tests. Inspection check lists are for 'laboratory management', 'clinical chemistry', 'diagnostic hematology', 'clinical microbiology', 'diagnostic immunology', 'transfusion medicine', 'cytogenetics', 'molecular genetics', 'histocompatibility', 'flow cytometry', and 'comprehensive laboratory test verification report'. The laboratories with score 90 or higher got 2-yr certificate and laboratories with score between 60 and 89 got 1-yr certificate. The laboratories with score below 60 failed accreditation.

RESULTS

The number of accredited laboratories was 2.4 times higher in 2006 (n=227) than in 1999 (n=96). Inspection check lists have been revised 5 times till 2006. The average accreditation rate was 99.6% during these periods and the 2-yr accreditation rate was 32.4% in 2000, 45.6% in 2001, 53.3% in 2002, 47.3% in 2003, 68.5% in 2004, 37.7% in 2005, and 47.7% in 2006. Number of participants in inspector training workshops increased from 89 in 2000 to 766 in 2006.

CONCLUSIONS

The KLAP has been in place successfully and stabilized over the past 8 yr. It seemed to enhance the laboratory quality. Efforts for improvement of quality control and inspector training workshops appeared to be in the main contributing factors.

Sero-epidemiology of hepatitis A virus infection among healthcare workers in Korean hospitals

Hepatitis A virus (HAV) has been increasingly reported in Korea as has an outbreak in Korean healthcare workers (HCWs). This 2008 study evaluated the sero-epidemiology of HAV infections among 3696 HCWs in four Korean hospitals. HCWs were tested for immunoglobulin G anti-HAV antibodies using commercially available kits. Data including demographic characteristics, occupation, workplace and serological status for other hepatitis viruses were collected. Statistical analyses were conducted to identify variables related to HAV seropositivity. Among the 3696 participants, 2742 (74%) were women and the majority (96%) were aged 20-39 years (median: 28; range: 19-68). Eighteen percent were physicians, 46% nurses, 10% nurses' aides, 11% paramedical technicians and 15% administrative staff. Seropositivity for HAV significantly increased with age (P<0.001): 1.8% for < or =24 years, 14.7% for 25-29 years, 41.8% for 30-34 years, 75.5% for 35-39 years, and 93.7% for > or =40 years. Among those aged 20-39 years, age-specific HAV seroprevalence was significantly lower in physicians than in the other occupational groups (P<0.001). In Korea, mass vaccination to HCWs aged < or =29 years or screening for seropositivity and vaccinating non-immune subjects aged 30-39 years should be considered, especially in physicians.

[Evaluation of the Phoenix automated microbiology system for detecting extended-spectrum beta-lactamase in Escherichia coli, Klebsiella species and Proteus mirabilis]

BACKGROUND

The aim of this study was to compare the BD Phoenix (Beckton Dickinson Diagnostic Systems, USA) extended-spectrum beta-lactamase (ESBL) test with the Clinical and Laboratory Standards Institute (CLSI) ESBL phenotypic confirmatory test by disk diffusion (CLSI ESBL test) in Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Proteus mirabilis.

METHODS

We tested 224 clinical isolates of E. coli, K. pneumoniae, K. oxytoca and P. mirabilis during May 2006 to March 2007. These isolates were examined by the Phoenix and the CLSI ESBL tests simultaneously. For the isolates showing discordant results between the two tests, boronic acid disk test was performed to differentiate AmpC beta-lactamase and ESBL.

RESULTS

Among the 224 clinical isolates, 75 and 79 isolates were positive for ESBL by CLSI ESBL test and Phoenix test, respectively. Having detected 4 more isolates as ESBL-producers, Phoenix test showed a 98.2% agreement with a 100% sensitivity and 97.3% specificity compared with CLSI ESBL test. Among the four false positive isolates, three were AmpC-positive but ESBL-negative.

CONCLUSIONS

The BD Phoenix ESBL test was sensitive and specific, and can be used as a rapid and reliable method to detect ESBL production in E. coli, Klebsiella species, and P. mirabilis.

Involvement of circulating endothelial progenitor cells and vasculogenic factors in the pathogenesis of diabetic retinopathy

PURPOSE

Retinal neovascularization in diabetes has been thought to follow the release of local angiogenic factors in the retina. We hypothesize that neovascularization of diabetic retinopathy is a systemic vasculogenesis rather than a local angiogenesis. Thus, we evaluate the concentrations of circulating endothelial progenitor cells (EPCs) and stem cell modulation factors such as vascular endothelial growth factor (VEGF), erythropoietin (Epo), and substance p (SP) in the peripheral blood of diabetic retinopathy patients.

METHODS

We studied 15 normal controls and 45 type II diabetic patients (no DR group (n=15), NPDR group (n=15), and PDR group (n=15)). We measured circulating CD34+mononuclear cells (CD34+MNCs), c-Kit+mononuclear cells (c-Kit+MNCs) by flow cytometry. VEGF, Epo, and SP in the peripheral blood were measured by ELISA.

RESULTS

The circulating CD34+MNCs and c-Kit+MNCs increased in the NPDR and PDR groups compared with the control group (P<0.01). Serum level of VEGF increased in the NPDR and PDR groups compared with the control group (P<0.05). The level of Epo elevated exclusively in the no DR group compared with the other three groups (P<0.01). Circulating SP level increased in the NPDR and PDR groups compared with the control group (P<0.05). SP and CD34+MNCs were shown to have increased correlation according to the diabetic retinopathy in the NPDR and PDR groups (r=0.440, P<0.05 and r=0.460, P<0.05, respectively).

CONCLUSIONS

The present study is the first to demonstrate that CD34+MNCs, c-Kit+MNCs and their modulator are elevated in diabetic retinopathy patients. Therefore, it is possible that circulating EPCs and serum Epo, VEGF, and SP may be involved in the progression of diabetic retinopathy.

Short report: genetic heterogeneity of Japanese encephalitis virus assessed via analysis of the full-length genome sequence of a Korean isolate

We determined the full-length genome sequence of Japanese encephalitis virus (JEV) K94P05 isolated in Korea. Sequence analysis showed that the 10,963-nucleotide-long RNA genome of K94P05 was 13 or 14 nucleotides shorter than the genome of other JEV isolates because of a deletion in the 3' noncoding region of K94P05. Compared with sequences of other JEV isolates, the full-length nucleotide sequence showed 89.0-89.6% homology, and the deduced amino acid sequence showed between 96.4-97.3% homology. A region of approximately 60 nucleotides immediately downstream of the open reading frame stop codon of K94P05 showed high sequence variability as compared with other JEV isolates. K94P05 formed a distinct group within a phylogenetic tree established with the full-length genome sequences. Cross-neutralization studies showed that polyclonal antibodies to Korean isolates were 3 times better at neutralizing the Korean isolates than antibodies to Nakayama-NIH. These findings suggest that Korean JEV K94P05 is genetically and antigenically distinct from other Asian JEV isolates.

Modification of cardiovascular responses to adenosine A1 receptor stimulation in the posterior hypothalamus of anaesthetized rats by cAMP and by GABA(B) receptor blockade

1 Injection of N(6)-cyclohexyladenosine (CHA; 1, 5 and 10 nmol), an adenosine A1 receptor agonist, into the posterior hypothalamus of rats produced a dose-dependent decrease in blood pressure (BP) and heart rate (HR). 2 Pretreatment with 8-cyclopentyl-1,3-dimethylxanthine (CPDX; 50 nmol), an adenosine A1 receptor antagonist, blocked the depressor and bradycardic effects of CHA (10 nmol). 3 Pretreatment with 8-bromo-cyclic adenosine monophosphate (AMP) (10 nmol), a cAMP analogue, attenuated the depressor and bradycardic effect of CHA (10 nmol); 8-bromo-cyclic guanosine monophosphate (GMP) (10 nmol), a cGMP analogue, did not modify those effects of CHA. 4 In addition, pretreatment with 5-aminovaleric acid (25 nmol), a gamma-aminobutyric acid (GABA)(B) receptor antagonist, attenuated the depressor and bradycardic effects of CHA (10 nmol). 5 These results suggest that adenosine A1 receptors in the posterior hypothalamus have an inhibitory role in the central cardiovascular regulation and that these vasodepressive and bradycardic actions are modified by raised cAMP and by GABA(B) receptor inhibition.

Protection against lethal Japanese encephalitis virus infection of mice by immunization with the highly attenuated MVA strain of vaccinia virus expressing JEV prM and E genes

Genes encoding the glycosylated precursor of the membrane (prM) and envelope (E) proteins of a Korean strain of Japanese encephalitis virus (JEV) were inserted into the genome of the host-range restricted, highly attenuated, and safety-tested MVA strain of vaccinia virus. MVA recombinants containing the JEV genes, under strong synthetic or modified H5 vaccinia virus promoters, were isolated. Synthesis of JEV prM and E proteins was detected by immunofluorescence microscopy, flow cytometry, and polyacrylamide gel electrophoresis. Mice inoculated and boosted by various routes with either of the MVA recombinants produced JEV neutralizing antibodies, that had titres comparable with those induced by an inactivated JEV vaccine, as well as haemagglutination-inhibiting antibodies. Mice immunized with 2 x 10(6) infectious units of MVA/JEV recombinants by intramuscular or intraperitoneal routes were completely protected against a 10(5) LD50 JEV challenge at 9 weeks of age.

Two vivax malaria cases detected in Korea

On June and July 1994, two cases of vivax malaria were consecutively diagnosed at the Yongsan Hospital, Chung-Ang University in Seoul. The first patient was a soldier serving in western parts of the demilitarized zone (DMZ) while the second case was a resident of a village near DMZ. Neither patients had history of being abroad. Republic of Korea (ROK) has been free of malaria since the mid-1970s except for imported cases. The two vivax malaria cases, together with an additional patient detected in 1993, occurred in relatively small areas near DMZ. This necessitated an epidemiologic surveillance. When medical records and blood smears in the areas were examined, no other cases were found. Of 7,723 mosquitoes collected by a black light trap for two nights in June, 7,066 (91.5%) were Anopheles sinensis. In order to evaluate a significance of the recent malaria occurrence, a surveillance system should be operated in the areas.