Attention-Guided Transfer Learning for Identification of Filamentous Fungi Encountered in the Clinical Laboratory

This study addresses the challenge of accurately identifying filamentous fungi in medical laboratories using transfer learning with convolutional neural networks (CNNs). The study uses microscopic images from touch-tape slides with lactophenol cotton blue staining, the most common method in clinical settings, to classify fungal genera and identify Aspergillus species. The training and test data sets included 4,108 images with representative microscopic morphology for each genus, and a soft attention mechanism was incorporated to enhance classification accuracy. As a result, the study achieved an overall classification accuracy of 94.9% for four frequently encountered genera and 84.5% for Aspergillus species. One of the distinct features is the involvement of medical technologists in developing a model that seamlessly integrates into routine workflows. In addition, the study highlights the potential of merging advanced technology with medical laboratory practices to diagnose filamentous fungi accurately and efficiently. IMPORTANCE This study utilizes transfer learning with CNNs to classify fungal genera and identify Aspergillus species using microscopic images from touch-tape preparation and lactophenol cotton blue staining. The training and test data sets included 4,108 images with representative microscopic morphology for each genus, and a soft attention mechanism was incorporated to enhance classification accuracy. As a result, the study achieved an overall classification accuracy of 94.9% for four frequently encountered genera and 84.5% for Aspergillus species. One of the distinct features is the involvement of medical technologists in developing a model that seamlessly integrates into routine workflows. In addition, the study highlights the potential of merging advanced technology with medical laboratory practices to diagnose filamentous fungi accurately and efficiently.

Using a Knowledge-Based Clinical Decision Support System to Reduce the Time to Appropriate Antimicrobial Therapy in Hospitalized Patients With Bloodstream Infections: A Single-Center Observational Study

BACKGROUND

Inappropriate antimicrobial use is a crucial determinant of mortality in hospitalized patients with bloodstream infections. Current literature reporting on the impact of clinical decision support systems on optimizing antimicrobial prescription and reducing the time to appropriate antimicrobial therapy is limited.

METHODS

Kaohsiung Veterans General Hospital implemented a hospital-wide, knowledge-based, active-delivery clinical decision support system, named RAPID (Real-time Alert for antimicrobial Prescription from virtual Infectious Diseases experts), to detect whether there was an antimicrobial agent-pathogen mismatch when a blood culture result was positive. Once RAPID determines the current antimicrobials as inappropriate, an alert text message is immediately sent to the clinicians in charge. This study evaluated how RAPID impacted the time to appropriate antimicrobial therapy among patients with bloodstream infections.

RESULTS

During the study period, 633 of 11 297 recorded observations (5.6%) were determined as inappropriate antimicrobial prescriptions. The time to appropriate antimicrobial therapy was significantly shortened after the implementation of RAPID (1.65 vs 2.45 hours, P < .001), especially outside working hours (1.24 vs 6.43 hours, P < .001), in the medical wards (1.40 vs 2.14 hours, P < .001), in participants with candidemia (0.74 vs 5.36 hours, P < .001), and for bacteremia due to non-multidrug-resistant organisms (1.66 vs 2.49 hours, P < .001).

CONCLUSIONS

Using a knowledge-based clinical decision support system to reduce the time to appropriate antimicrobial therapy in a real-world scenario is feasible and effective. Our results support the continued use of RAPID.

High-Integrity Sequencing of Spike Gene for SARS-CoV-2 Variant Determination

For tiling of the SARS-CoV-2 genome, the ARTIC Network provided a V4 protocol using 99 pairs of primers for amplicon production and is currently the widely used amplicon-based approach. However, this technique has regions of low sequence coverage and is labour-, time-, and cost-intensive. Moreover, it requires 14 pairs of primers in two separate PCRs to obtain spike gene sequences. To overcome these disadvantages, we proposed a single PCR to efficiently detect spike gene mutations. We proposed a bioinformatic protocol that can process FASTQ reads into spike gene consensus sequences to accurately call spike protein variants from sequenced samples or to fairly express the cases of missing amplicons. We evaluated the in silico detection rate of primer sets that yield amplicon sizes of 400, 1200, and 2500 bp for spike gene sequencing of SARS-CoV-2 to be 59.49, 76.19, and 92.20%, respectively. The in silico detection rate of our proposed single PCR primers was 97.07%. We demonstrated the robustness of our analytical protocol against 3000 Oxford Nanopore sequencing runs of distinct datasets, thus ensuring high-integrity sequencing of spike genes for variant SARS-CoV-2 determination. Our protocol works well with the data yielded from versatile primer designs, making it easy to determine spike protein variants.

Low Seroprevalence of Aichi Virus Infection in Taiwan

Aichi virus (AiV) belongs to the genus Kobuvirus of the family Picornaviridae; it is a single-stranded positive-sense RNA virus without an envelope. AiV causes acute gastroenteritis, abdominal pain, nausea, vomiting, and fever. Low incidence and high seroprevalence of AiV infections have been reported in several regions of the world; however, little was known on the prevalence of AiV infections in Taiwan. This study described the first two cases of AiV infection and analyzed AiV seroprevalence in Taiwan. A total of 700 sera were collected from a single hospital in southern Taiwan. The neutralization assay was employed to assess AiV neutralization antibodies in the serum. The test identified 48 positive cases, with a seroprevalence of 6.86%. Results also showed a gradual increase in AiV seroprevalence rate with age. Compared with other countries, Taiwan had a relatively low AiV seroprevalence, suggesting a low incidence of or sporadic AiV infections.

Detection of carbapenem-resistant Klebsiella pneumoniae on the basis of matrix-assisted laser desorption ionization time-of-flight mass spectrometry by using supervised machine learning approach

BACKGROUND

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is emerging as a significant pathogen causing healthcare-associated infections. Matrix-assisted laser desorption/ionisation mass spectrometry time-of-flight mass spectrometry (MALDI-TOF MS) is used by clinical microbiology laboratories to address the need for rapid, cost-effective and accurate identification of microorganisms. We evaluated application of machine learning methods for differentiation of drug resistant bacteria from susceptible ones directly using the profile spectra of whole cells MALDI-TOF MS in 46 CRKP and 49 CSKP isolates.

METHODS

We developed a two-step strategy for data preprocessing consisting of peak matching and a feature selection step before supervised machine learning analysis. Subsequently, five machine learning algorithms were used for classification.

RESULTS

Random forest (RF) outperformed other four algorithms. Using RF algorithm, we correctly identified 93% of the CRKP and 100% of the CSKP isolates with an overall classification accuracy rate of 97% when 80 peaks were selected as input features.

CONCLUSIONS

We conclude that CRKPs can be differentiated from CSKPs through RF analysis. We used direct colony method, and only one spectrum for an isolate for analysis, without modification of current protocol. This allows the technique to be easily incorporated into clinical practice in the future.

Parechovirus A Detection by a Comprehensive Approach in a Clinical Laboratory

Parechovirus A (Human parechovirus, HPeV) causes symptoms ranging from severe neonatal infection to mild gastrointestinal and respiratory disease. Use of molecular approaches with RT-PCR and genotyping has improved the detection rate of HPeV. Conventional methods, such as viral culture and immunofluorescence assay, together with molecular methods facilitate comprehensive viral diagnosis. To establish the HPeV immunofluorescence assay, an antibody against HPeV capsid protein VP0 was generated by using antigenic epitope prediction data. The specificity of the anti-HPeV VP0 antibody was demonstrated on immunofluorescence assay, showing that this antibody was specific for HPeV but not enteroviruses. A total of 74 HPeV isolates, 7 non–polio-enteroviruses and 12 HPeV negative cell culture supernatant were used for evaluating the efficiency of the anti-HPeV VP0 antibody. The sensitivity of HPeV detection by the anti-HPeV VP0 antibody was consistent with 5′untranslated region (UTR) RT-PCR analysis. This study established comprehensive methods for HPeV detection that include viral culture and observation of cytopathic effect, immunofluorescence assay, RT-PCR and genotyping. The methods were incorporated into our routine clinical practice for viral diagnosis. In conclusion, this study established a protocol for enterovirus and HPeV virus identification that combines conventional and molecular methods and would be beneficial for HPeV diagnosis.

Human Parechovirus Infection in Children in Taiwan: a Retrospective, Single-Hospital Study

To understand human parechovirus (HPeV) infections in Taiwanese children, we analyzed data for 112 children (age≤10 years) with HPeV infection diagnosed between July 2007 and June 2016 in a medical center in Kaohsiung, southern Taiwan. The patients were infected with HPeV1 (n=94), HPeV3 (n=3), HPeV4 (n=3), HPeV6 (n=1) and non-typeable HPeV (n=11). We compared the clinical implications for children younger than 3 months (n=56) and 3 months and older (n=31), excluding 25 children with concomitant infections. Fever was noted in almost half of the children younger than 3 months but was more frequent in older than in younger children (83.9% vs 46.4%). As compared with older children, children younger than 3 months had a lower incidence of respiratory symptoms (30.1% vs 83.9%), more frequently required intensive care unit admission (28.6% vs 3.2%), and had longer hospital stays (mean 10.95 vs 5.13 days). Importantly, about one-third of the children were suspected to have hospital-acquired or cluster infections in the environment of medical institutions, with a significantly high proportion of 42.9% (24/56) in younger infants. Hospital-acquired infections might play a key role in the spread of HPeV, especially in children younger than 3 months.

Evaluation of a matrix-assisted laser desorption ionization-time of flight mass spectrometry assisted, selective broth method to screen for vancomycin-resistant enterococci in patients at high risk

BACKGROUND

Bile esculin azide with vancomycin (BEAV) medium is a sensitive, but slightly less specific method for vancomycin-resistant enterococci (VRE) screening. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid method for identification of clinical pathogens. This study aimed to assess the performance of a novel combination screening test for VRE, using BEAV broth combined with MALDI-TOF MS.

MATERIALS AND METHODS

Clinical specimens were collected from patients at risk of VRE carriage, and tested by the novel combination method, using selective BEAV broth culture method followed by MALDI-TOF MS identification (SBEAVM). The reference method used for comparison was the ChromID VRE agar method.

RESULTS

A total of 135 specimens were collected from 78 patients, and 63 specimens tested positive for VRE positive using the ChromID VRE method (positive rate 46.7%). The sensitivity, specificity, positive predictive value, and negative predictive value of SBEAVM method after an incubation period of 28 hours were 93.7%, 90.3%, 89.4%, and 94.2%, respectively. The SBEAVM method when compared to the ChromID VRE method had a shorter turnaround time (29 vs. 48-72 hours) and lower laboratory cost ($2.11 vs. $3.23 per test).

CONCLUSIONS

This study demonstrates that SBEAVM is a rapid, inexpensive, and accurate method for use in VRE screening.

Isolation of dengue virus from the upper respiratory tract of four patients with dengue fever

Background

Dengue fever is an important arboviral disease. The clinical manifestations vary from a mild non-specific febrile syndrome to severe life-threatening illness. The virus can usually be detected in the blood during the early stages of the disease. Dengue virus has also been found in isolated cases in the cerebrospinal fluid, urine, nasopharyngeal sections and saliva. In this report, we describe the isolation of dengue virus from the upper respiratory tract of four confirmed cases of dengue.

Methods

We reviewed all laboratory reports of the isolation of dengue virus from respiratory specimens at the clinical microbiology laboratory of the Kaohsiung Veterans General Hospital during 2007 to 2015. We then examined the medical records of the cases from whom the virus was isolated to determine their demographic characteristics, family contacts, clinical signs and symptoms, course of illness and laboratory findings.

Results

Dengue virus was identified in four patients from a nasopharyngeal or throat culture. Two were classified as group A dengue (dengue without warning signs), one as group B (dengue with warning signs) and one as group C (severe dengue). All had respiratory symptoms. Half had family members with similar respiratory symptoms during the period of their illnesses. All of the patients recovered uneventfully.

Conclusions

The isolation of dengue virus from respiratory specimens of patients with cough, rhinorrhea and nasal congestion, although rare, raises the possibility that the virus is capable of transmission by the aerosol route among close contacts. This concept is supported by studies that show that the virus can replicate in cultures of respiratory epithelium and can be transmitted through mucocutaneous exposure to blood from infected patients. However, current evidence is insufficient to prove the hypothesis of transmission through the respiratory route. Further studies will be needed to determine the frequency of respiratory colonization, viable virus titers in respiratory secretions and molecular genetic evidence of transmission among close contacts.

Dengue virus is rarely identified in respiratory specimens. We retrospectively identified four patients with dengue fever who had the virus isolated from their nose or throat. All the patients had respiratory signs or symptoms. Half had family members who also had respiratory symptoms. Further studies are needed to evaluate the possibility of respiratory transmission of this virus.

Characterization and Mechanism for the Protection of Photolytic Decomposition of N-Halamine Siloxane Coatings by Titanium Dioxide

N-Halamine antibacterial materials have superior inactivation activities due to oxidative chlorine species. However, N-Cl bonds and bonds between N-halamine and substrates often decompose rapidly under UV irradiation, leading to unrecoverable loss of antimicrobial activity. In this study, titanium dioxide was covalently bonded onto N-halamine siloxane poly[5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin] (PSPH) via a sol-gel process. Experimental testing of the chlorinated cotton fabrics treated with TiO2/PSPH demonstrated that the residual oxidative chlorine in cotton-TiO2/PSPH-Cl was still effective for inactivating bacteria after 50 washing cycles and under UV light irradiation for 24 h. Quantum mechanical calculations found that TiO2 improves the UV stability of the PSPH-Cl system by increasing the activation barrier of the C-Si scission reaction responsible for the loss of the biocidal hydantoin moiety. SEM, XPS and FTIR spectra were used to characterize the coated cotton samples. Cotton-TiO2/PSPH-Cl samples exhibited good antibacterial activity against Staphylococcus aureus (ATCC 6538) and Escherichia coli O157:H7 (ATCC 43895). The storage stability and washing stability of treated cotton fabrics were also investigated.

Phylodynamic reconstruction of the spatiotemporal transmission and demographic history of coxsackievirus B2

BACKGROUND

Studies regarding coxsackievirus (CV) tend to focus on epidemic outbreaks, an imbalanced topology is considered to be an indication of acute infection with partial cross-immunity. In enteroviruses, a clear understanding of the characteristics of tree topology, transmission, and its demographic dynamics in viral succession and circulation are essential for identifying prevalence trends in endemic pathogens such as coxsackievirus B2 (CV-B2). This study applied a novel Bayesian evolutionary approach to elucidate the phylodynamic characteristics of CV-B2. A dataset containing 51 VP1 sequences and a dataset containing 34 partial 3D(pol) sequencing were analyzed, where each dataset included Taiwan sequences isolated during 1988-2013.

RESULTS

Four and five genotypes were determined based on the 846-nucleotide VP1 and 441-nucleotide 3D(pol) (6641-7087) regions, respectively, with spatiotemporally structured topologies in both trees. Some strains with tree discordance indicated the occurrence of recombination in the region between the VP1 and 3D(pol) genes. The similarities of VP1 and 3D(pol) gene were 80.0%-96.8% and 74.7%-91.9%, respectively. Analyses of population dynamics using VP1 dataset indicated that the endemic CV-B2 has a small effective population size. The balance indices, high similarity, and low evolutionary rate in the VP1 region indicated mild herd immunity selection in the major capsid region.

CONCLUSIONS

Phylodynamic analysis can reveal demographic trends and herd immunity in endemic pathogens.

Transmission and Demographic Dynamics of Coxsackievirus B1

The infectious activity of coxsackievirus B1 (CV-B1) in Taiwan was high from 2008 to 2010, following an alarming increase in severe neonate disease in the United States (US). To examine the relationship between CV-B1 strains isolated in Taiwan and those from other parts of the world, we performed a phylodynamic study using VP1 and partial 3Dpol (414 nt) sequences from 22 strains of CV-B1 isolated in Taiwan (1989-2010) and compared them to sequences from strains isolated worldwide. Phylogenetic trees were constructed by neighbor-joining, maximum likelihood, and Bayesian Monte Carlo Markov Chain methods. Four genotypes (GI-IV) in the VP1 region of CV-B1 and three genotypes (GA-C) in the 3Dpol region of enterovirus B were identified and had high support values. The phylogenetic analysis indicates that the GI and GIII strains in VP1 were geographically distributed in Taiwan (1993-1994) and in India (2007-2009). On the other hand, the GII and GIV strains appear to have a wider spatiotemporal distribution and ladder-like topology A stair-like phylogeny was observed in the VP1 region indicating that the phylogeny of the virus may be affected by different selection pressures in the specified regions. Further, most of the GI and GII strains in the VP1 tree were clustered together in GA in the 3D tree, while the GIV strains diverged into GB and GC. Taken together, these data provide important insights into the population dynamics of CV-B1 and indicate that incongruencies in specific gene regions may contribute to spatiotemporal patterns of epidemicity for this virus.

Self-assembled antibacterial coating by N-halamine polyelectrolytes on a cellulose substrate

In this research, two N-halamine polymer precursors, a cationic homopolymer poly((3-acrylamidopropyl)trimethylammonium chloride) (CHP) and an anionic homopolymer poly(2-acrylamido-2-methylpropane sulfonic acid sodium salt) (AHP), have been successfully synthesized and coated onto cotton fabrics via a layer-by-layer (LbL) deposition technique. The coated cotton fabrics were characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The biocidal efficacies of uncoated and coated cotton fabrics were evaluated against Staphylococcus aureus and Escherichia coli. The chlorinated swatches (CHP-Cl and AHP-Cl) inactivated 100% S. aureus and 99.73% E. coli O157:H7 in 30 min. Over 51% of the chlorine is retained after the equivalent of 50 machine washes. A skin stimulation test showed that CHP-Cl and AHP-Cl compounds have no irritation to rabbit skin, and so these swatches might be utilized for biomedical applications in the future. As an easy and efficient way of coating fabrics, the LbL deposition technique can broaden the use of N-halamine biocides in other polar substances as antimicrobial functional coatings.

Functional ginger extracts from supercritical fluid carbon dioxide extraction via in vitro and in vivo assays: antioxidation, antimicroorganism, and mice xenografts models

Supercritical fluid carbon dioxide extraction technology was developed to gain the active components from a Taiwan native plant, Zingiber officinale (ginger). We studied the biological effects of ginger extracts via multiple assays and demonstrated the biofunctions in each platform. Investigations of ginger extracts indicated antioxidative properties in dose-dependant manners on radical scavenging activities, reducing powers and metal chelating powers. We found that ginger extracts processed moderate scavenging values, middle metal chelating levels, and slight ferric reducing powers. The antibacterial susceptibility of ginger extracts on Staphylococcus aureus, Streptococcus sobrinus, S. mutans, and Escherichia coli was determined with the broth microdilution method technique. The ginger extracts had operative antimicroorganism potentials against both Gram-positive and Gram-negative bacteria. We further discovered the strong inhibitions of ginger extracts on lethal carcinogenic melanoma through in vivo xenograft model. To sum up, the data confirmed the possible applications as medical cosmetology agents, pharmaceutical antibiotics, and food supplements.

High sensitivity, low noise Mirnov coil array on Prairie View rotamak

An array of 32 Mirnov coils with novel features of high sensitivity and low noise has been installed on the outside chamber surface of Prairie View rotamak. This B(R)-oriented coil array has proven to be very reliable in the plasma driven by rotating magnetic field; it can resolve magnetic perturbation signals of 0.1 G. With this new diagnostic, the n = 1 tilt, radial shift, and kink modes are observed for the first time in rotamak plasmas.

Clonal expansion of both modern and ancient genotypes of Mycobacterium tuberculosis in southern Taiwan

We present the first comprehensive analysis of Mycobacterium tuberculosis isolates circulating in the Kaohsiung region of southern Taiwan. The major spoligotypes found in the 224 isolates studied were Beijing lineages (n = 97; 43.3%), EAI lineages (n = 72; 32.1%) and Haarlem lineages (n = 18; 8.0%). By 24 MIRU-VNTR typing, 174 patterns were identified, including 24 clusters of 74 isolates and 150 unique patterns. The combination of spoligotyping and 12-MIRU-VNTR revealed that 129 (57.6%) of the 224 isolates were clustered in 18 genotypes. Moreover, 63.6% (7/11) of infected persons younger than 30 years had a Beijing strain, which could suggest recent spread among younger persons by this family of TB strains in Kaohsiung. Among the 94 Beijing family (SIT1, SIT250 and SIT1674) isolates further analyzed for SNPs by mass spectrometry, the most frequent strain found was ST10 (n = 49; 52%), followed by ST22 (n = 17; 18%) and ST19 (n = 11; 12%). Among the EAI-Manila family isolates analyzed by region deletion-based subtyping, the most frequent strain found was RD type 1 (n = 63; 87.5%), followed by RD type 2 (n = 9; 12.5%). In our previous study, the proportion of modern Beijing strains (52.5%) in northern Taiwan was significantly higher than the proportion of EAI strains (11%). In contrast, in the present study, EAI strains comprised up to 32% of Beijing strains in southern Taiwan. In conclusion, both ‘modern’ (Beijing) and ‘ancient’ (EAI) M. tuberculosis strains are prevalent in the Kaohsiung region, perhaps suggesting that both strains are somehow more adapted to southern Taiwan. It will be interesting to investigate the dynamics of the lineage composition by different selection pressures.

Genetic diversity of the Mycobacterium tuberculosis Beijing family based on SNP and VNTR typing profiles in Asian countries

The Mycobacterium tuberculosis (MTB) Beijing strain is highly virulent, drug resistant, and endemic over Asia. To explore the genetic diversity of this family in several different regions of eastern Asia, 338 Beijing strains collected in Taiwan (Republic of China) were analyzed by mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing and compared with published MIRU-VNTR profiles and by the Hunter-Gaston diversity index (HGDI) of Beijing strains from Japan and South Korea. The results revealed that VNTR2163b (HGDI>0.6) and five other loci (VNTR424, VNTR4052, VNTR1955, VNTR4156 and VNTR 2996; HGDI>0.3) could be used to discriminate the Beijing strains in a given geographic region. Analysis based on the number of VNTR repeats showed three VNTRs (VNTR424, 3192, and 1955) to be phylogenetically informative loci. In addition, to determine the geographic variation of sequence types in MTB populations, we also compared sequence type (ST) data of our strains with published ST profiles of Beijing strains from Japan and Thailand. ST10, ST22, and ST19 were found to be prevalent in Taiwan (82%) and Thailand (92%). Furthermore, classification of Beijing sublineages as ancient or modern in Taiwan was found to depend on the repeat number of VNTR424. Finally, phylogenetic relationships of MTB isolates in Taiwan, South Korea, and Japan were revealed by a minimum spanning tree based on MIRU-VNTR genotyping. In this topology, the MIRU-VNTR genotypes of the respective clusters were tightly correlated to other genotypic characters. These results are consistent with the hypothesis that clonal evolution of these MTB lineages has occurred.

Biological properties of acidic cosmetic water from seawater

This current work was to investigate the biological effects of acidic cosmetic water (ACW) on various biological assays. ACW was isolated from seawater and demonstrated several bio-functions at various concentration ranges. ACW showed a satisfactory effect against Staphylococcus aureus, which reduced 90% of bacterial growth after a 5-second exposure. We used cultured human peripheral blood mononuclear cells (PBMCs) to test the properties of ACW in inflammatory cytokine release, and it did not induce inflammatory cytokine release from un-stimulated, normal PBMCs. However, ACW was able to inhibit bacterial lipopolysaccharide (LPS)-induced inflammatory cytokine TNF-α released from PBMCs, showing an anti-inflammation potential. Furthermore, ACW did not stimulate the rat basophilic leukemia cell (RBL-2H3) related allergy response on de-granulation. Our data presented ACW with a strong anti-oxidative ability in a superoxide anion radical scavenging assay. In mass spectrometry information, magnesium and zinc ions demonstrated bio-functional detections for anti-inflammation as well as other metal ions such as potassium and calcium were observed. ACW also had minor tyrosinase and melanin decreasing activities in human epidermal melanocytes (HEMn-MP) without apparent cytotoxicity. In addition, the cell proliferation assay illustrated anti-growth and anti-migration effects of ACW on human skin melanoma cells (A375.S2) indicating that it exerted the anti-cancer potential against skin cancer. The results obtained from biological assays showed that ACW possessed multiple bioactivities, including anti-microorganism, anti-inflammation, allergy-free, antioxidant, anti-melanin and anticancer properties. To our knowledge, this was the first report presenting these bioactivities on ACW.

Epidemiology of group B Streptococcus ST-17 clone in pregnant women of South Taiwan

OBJECTIVES

We aimed to utilize a simple molecular assay to simultaneously detect both group B Streptococcus (GBS) and virulent ST-17 rectovaginal colonization. We also attempted to estimate the prevalence of maternal GBS and ST-17 carriers and to evaluate their seasonal association.

SUBJECTS AND METHODS

We used an optimized multiplex PCR method employing scp-B and ST-17 primers to analyze DNA extracted from rectovaginal swabs of 3,064 cases collected over 3 years. The incidence trends, seasonal variations, and temperature preference were analyzed.

RESULTS

The overall prevalence of maternal colonization for GBS and ST-17 clone were 13.25 and 2.48%, respectively. The ST-17 to GBS ratio was 18.72%. The occurrence of ST-17 colonization was significantly associated with seasonal variations with a preference for lower temperatures.

CONCLUSIONS

We developed a novel multiplex PCR method suitable for the simultaneous detection of GBS and ST-17 clone. The phenomenon of lower temperature preference for ST-17 clone necessitates further investigation. The epidemiological data for GBS and ST-17 incidence are especially important to establish a public policy for universal GBS screening in the future.

Polymeric antimicrobial N-halamine epoxides

A new N-halamine copolymer has been prepared, characterized, and evaluated for antimicrobial efficacy, stability toward hydrolyses, and stability toward UVA degradation when covalently bound to cellulose fibers. A copolymer of 3-chloro-2-hydroxypropylmethacrylate and glycidyl methacrylate was coated onto cotton, and, after curing, was treated with an aqueous solution containing the potassium salt of 5,5-dimethylhydantoin to form a coating which became antimicrobial upon exposure to househod bleach (sodium hypochlorite). The coating inactivated S. aureus and E. coli O157:H7 within minutes of contact time and was quite stable toward washing and UVA photodegradation.

N-halamine copolymers for use in antimicrobial paints

A series of copolymers containing units of a novel hydantoinylacrylamide and the sodium salt of 2-(acrylamido)-2-methylpropanesulfonic acid have been synthesized. The homopolymer of the hydantoinylacrylamide compound was insoluble in water, while the copolymers with the sulfonic acid sodium salt were water-dispersible/soluble, with the solution becoming completely transparent when the feed ratio for the copolymer contained 7 parts of the hydantoin moiety to 3 parts of the sodium sulfonate moiety. The polymers were added into a commercial water-based latex paint, and upon drying, the painted surfaces treated with the water-miscible copolymers were rendered antimicrobial following chlorination with dilute household bleach. The chlorinated homopolymer failed to provide an antimicrobial property for the paint because of its tendency to isolate into aggregates in the paint, while the completely miscible copolymers were capable of 6-log inactivation of Staphylococcus aureus and Escherichia coli O157:H7 within 5 min of contact time.

N-halamine biocidal coatings via a layer-by-layer assembly technique

Two N-halamine copolymer precursors, poly(2,2,6,6-tetramethyl-4-piperidyl methacrylate-co-acrylic acid potassium salt) and poly(2,2,6,6-tetramethyl-4-piperidyl methacrylate-co-trimethyl-2-methacryloxyethylammonium chloride) have been synthesized and successfully coated onto cotton fabric via a layer-by-layer (LbL) assembly technique. A multilayer thin film was deposited onto the fiber surfaces by alternative exposure to polyelectrolyte solutions. The coating was rendered biocidal by a dilute household bleach treatment. The biocidal efficacies of tested swatches composed of treated fibers were evaluated against Staphylococcus aureus and Escherichia coli. It was determined that chlorinated samples inactivated both S. aureus and E. coli O157:H7 within 15 min of contact time, whereas the unchlorinated control samples did not exhibit significant biocidal activities. Stabilities of the coatings toward washing and ultraviolet light exposure have also been studied. It was found that the stability toward washing was superior, whereas the UVA light stability was moderate compared to previously studied N-halamine moieties. The layer-by-layer assembly technique can be used to attach N-halamine precursor polymers onto cellulose surfaces without using covalently bonding tethering groups which limit the structure designs. In addition, ionic precursors are very soluble in water, thus promising for biocidal coatings without the use of organic solvents.

Clinical significance of isolation of Mycobacterium avium complex from respiratory specimens

BACKGROUND/PURPOSE

Mycobacterium avium complex (MAC) is frequently considered to be a contaminant or transient colonizer. To the best of our knowledge, there have been very few reports regarding the clinical significance of MAC isolates in respiratory specimens, and the associated disease spectrum in Taiwan. The purpose of this study was to investigate the clinical significance of MAC isolates in respiratory specimens.

METHODS

We retrospectively reviewed the medical records of patients in a medical center in Southern Taiwan from whom MAC isolates were recovered from respiratory specimens, and analyzed their clinical features, chest imaging findings, treatment and prognosis. We also performed an antibiotic susceptibility test on our MAC isolates.

RESULTS

The 64 isolates used in this study were recovered from April to October 2001 from respiratory specimens in 54 patients admitted to Kaohsiung Veterans General Hospital, Taiwan. According to the 2007 criteria of the American Thoracic Society, a total of 12 patients (22.2%) had clinically significant MAC pulmonary disease.

CONCLUSION

Despite the increased frequency of recovering MAC from respiratory specimens, most cases did not meet the criteria of American Thoracic Society for clinically significant nontuberculous pulmonary disease. The minimum inhibitory concentrations of drugs against these MAC isolates might help to guide treatment, but further studies should be done.

High prevalence of latent tuberculosis infection in dialysis patients using the interferon-gamma release assay and tuberculin skin test

BACKGROUND AND OBJECTIVES

Patients in ESRD on hemodialysis with latent tuberculosis (TB) infection have 10 to 25 times the risk of reactivation into active disease compared with healthy adults. This study investigates the prevalence of latent TB infection in dialysis patients from a country with an intermediate burden of TB and its associated risk factors using the QuantiFERON-TB Gold in-tube test (QGIT) and the tuberculin skin test (TST).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective, cross-sectional study performed at a medical center in Taiwan on dialysis patients. Each patient underwent QGIT, two-step TST using 2 tuberculin units (TU) of PPD RT-23, a chest x-ray to exclude active TB, and an interview to determine TB risk factors.

RESULTS

Ninety-three of 190 eligible patients were enrolled: 35 men and 58 women. 64.8% were vaccinated with the Bacille-Calmette-Guérin (BCG) vaccination. Overall, 34.4% were positive by QGIT and 10.8% were indeterminate. Using a 10-mm TST cutoff, 53.9% were positive. There was poor correlation between TST and QGIT at any TST cutoff criteria. There was a significant increasing trend of QGIT positivity with age in those younger than 70 years, and, conversely, a decreasing trend of TST reactivity with age. Significant risk factors for QGIT positivity included age and past TB disease.

CONCLUSIONS

This study shows a high prevalence of latent TB infection in dialysis patients in a country with an intermediate burden of TB. QGIT in dialysis patients correlated better than TST with the risk of TB infection and past TB disease.

Suppression of n=1 tilt instability by magnetic shaping coils in Rotamak plasmas

Measurements from the array of Mirnov magnetic coils provide the first evidence for n=1 tilt and radial shift instabilities in a 40 ms field-reversed configuration (FRC) driven by rotating magnetic field. External plasma-shaping magnetic coils are utilized to suppress the n=1 instability modes. It is demonstrated that by energizing the middle shaping coil with 250-500 A current, the tilt mode is completely suppressed when a doublet FRC with an internal figure-of-eight separatrix is formed.

Comparison of the interferon- gamma release assay and the tuberculin skin test for contact investigation of tuberculosis in BCG-vaccinated health care workers

Health care workers are at increased risk of Mycobacterium tuberculosis infection. The tuberculin skin test (TST) is frequently false positive in BCG-vaccinated health care workers. QuantiFERON-TB GOLD (QFT-G) is a sensitive and specific interferon-gamma release assay unaffected by BCG vaccination. This study compared TST and QFT-G in the diagnosis of latent TB infection in BCG-vaccinated health care workers. 39 health care workers exposed to a smear-positive TB patient were enrolled. Initial TST was positive in 33 (84.6%) cases, but only 4 (10.2%) cases using QFT-G. TST conversion occurred in 2/6 (33.3%), compared to 4/32(12.5%), cases using QFT-G. A higher proportion of QFT converters was associated with intimate contact, although not reaching statistical significance. Face-to-face contact >1 h was significantly associated with QFT-G conversion >or=0.7 IU/ml (OR 8.63, 95%CI 1.08-69.07, p=0.04). Agreement between TST and QFT-G was 18.0%, (kappa: -0.03). Concordance between TST and QFT (>or=0.35 IU/ml) conversion was 40.0%(kappa=-0.40), and 60.0%(kappa=0.00) if QFT >or=0.7 IU/ml was used. Agreement increased with increasing TST cut-offs. TST is not useful in contact investigation among BCG-vaccinated health care workers, in an area with intermediate burden of TB. QFT may provide additional information for the diagnosis and strategic management of preventive treatment of LTBI in BCG-vaccinated health care workers in a country with intermediate burden of TB.

Role of genotype and precore/basal core promoter mutations of hepatitis B virus in patients with chronic hepatitis B with acute exacerbation

OBJECTIVE

The results of long-term, follow-up studies show that the severity and frequency of acute exacerbation of chronic hepatitis B virus (HBV) are associated with the development of liver cirrhosis in chronic HBV infection. The aim of this study was to investigate the relationship between virological factors of HBV and the severity of acute exacerbation.

MATERIAL AND METHODS

Fifty-one chronic hepatitis B patients with symptomatic acute exacerbation without antiviral therapy were enrolled in the study. Genotype of HBV was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Precore (A1896) and basal core promoter (BCP) mutations (T1762 & A1764) were determined by PCR and direct sequencing.

RESULTS

Thirty-nine patients had genotype B, 11 patients had genotype C, and 1 patient had an unclassified genotype. Thirty-two patients had precore mutation and 24 patients had BCP mutation. After adjusting for age, gender, aspartate aminotransferase (ASAT) level, albumin level, and platelet count by multiple logistic regression test, precore mutation had a protective effect on the occurrence of hepatic decompensation (p=0.046), and genotype and BCP mutations were not associated with the occurrence of hepatic decompensation.

CONCLUSIONS

HBV precore mutation may confer less severe liver disease during acute exacerbation of chronic HBV. Genotype and BCP mutations did not have a significant association with the occurrence of hepatic decompensation.

Clinical application of reverse-transcription polymerase chain reaction and intravenous immunoglobulin for enterovirus encephalitis

Although polymerase chain reaction (PCR) is a highly sensitive procedure for the diagnosis of enteroviruses, it has never been systemically applied to the treatment of enteroviral encephalitis using intravenous immunoglobulin (IVIg). We conducted a 2-year randomized, controlled comparison of reverse transcription (RT)-PCR of cerebrospinal fluid (CSF) with traditional viral isolation to guide IVIg treatment. Seventy-five patients were enrolled and classified into three groups: one group with clinical manifestations of enteroviral infections and two without. The latter two groups were separated on the basis of whether IVIg treatment was guided by RT-PCR or virus culture assay. CSF specimens from the 18 confirmed cases of enteroviral encephalitis were RT-PCR positive for enterovirus in all but one case. Of the remaining 57 cases of nonenteroviral encephalitis, only 4 were positive for enterovirus RT-PCR. One patient in the group of IVIg treatment guided by viral isolation subsequently displayed a sequel of epilepsy. No patients in the IVIg treatment groups guided by RT-PCR had any neurological sequelae. In conclusion, the use of RT-PCR allowed rapid, sensitive, and specific detection of enteroviral RNA in CSF. When used to guide IVIg treatment, RT-PCR may shorten hospitalization and improve outcomes of patients with enteroviral encephalitis.

Immune responses to foot-and-mouth disease virus in pig farms after the 1997 outbreak in Taiwan

This paper reports on a retrospective study of the antibody responses to structural and non-structural proteins of FMD virus O Taiwan 97 in six pig herds in Taiwan in the year after the 1997 Taiwanese FMD outbreak. All herds were vaccinated against FMD after the outbreak as part of the countrywide control program. Three of the herds had confirmed FMD infections (herds N, O and P) and three herds remained non-infected (herds K, L and M). The serum neutralizing antibody titers and the non-structural protein ELISA (NSP) antibody responses in sows and 1-month-old pigs in the infected herds were higher than in the non-infected herds, but over time a number of positive NSP reactors were detected. From the serological studies and the herd monitoring and investigations it was considered that the FMD NSP positive reactors may not have constituted a true reservoir of FMD virus infection especially in herds where susceptible pigs were no longer present post-exposure or post-vaccination. Pigs vaccinated with an unpurified FMD type O vaccines being used at that time also showed false positive responses for NSP antibodies.

Use of a disposable water filter for prevention of false-positive results due to nontuberculosis mycobacteria in a clinical laboratory performing routine acid-fast staining for tuberculosis

A point-of-use 0.2-microm filter was evaluated for elimination of nontuberculosis mycobacteria in laboratory water to reduce false-positive acid-fast bacillus staining results. Use of the point-of-use filter can significantly reduce the false-positive rate to 1.2% compared to samples treated with tap water (10.7%) and deionized water (8.7%).

Rapid and sensitive magnetoelastic biosensors for the detection of Salmonella typhimurium in a mixed microbial population

In this article, we report the results of an investigation into the performance of a wireless, magnetoelastic biosensor designed to selectively detect Salmonella typhimurium in a mixed microbial population. The Langmuir-Blodgett (LB) monolayer technique was employed for antibody (specific to Salmonella sp.) immobilization on rectangular shaped strip magnetoelastic sensors (2 x 0.4 x 0.015 mm). Bacterial binding to the antibody on the sensor surface changes the resonance parameters, and these changes were quantified as a shift in the sensor's resonance frequency. Response of the sensors to increasing concentrations (5 x 10(1) to 5 x 10(8) cfu/ml) of S. typhimurium in a mixture of extraneous foodborne pathogens (Escherichia coli O157:H7 and Listeria monocytogenes) was studied. A detection limit of 5 x 10(3) cfu/ml and a sensitivity of 139 Hz/decade were observed for the 2 x 0.4 x 0.015 mm sensors. Binding kinetics studies have shown that the dissociation constant (K(d)) and the binding valencies for water samples spiked with S. typhimurium was 435 cfu/ml and 2.33 respectively. The presence of extraneous microorganisms in the mixture did not produce an appreciable change in the biosensor's dose response behavior.

A magnetoelastic resonance biosensor immobilized with polyclonal antibody for the detection of Salmonella typhimurium

Mass-sensitive, magnetoelastic resonance sensors have a characteristic resonant frequency that can be determined by monitoring the magnetic flux emitted by the sensor in response to an applied, time varying, magnetic field. This magnetostrictive platform has a unique advantage over conventional sensor platforms in that measurement is wireless and remote. A biosensor for the detection of Salmonella typhimurium was constructed by immobilizing a polyclonal antibody (the bio-molecular recognition element) onto the surface of a magnetostrictive platform. The biosensor was then exposed to solutions containing S. typhimurium bacteria. Binding between the antibody and antigen (bacteria) occurred and the additional mass of the bound bacteria caused a shift in the sensor's resonant frequency. Sensors with different physical dimensions were exposed to different concentrations of S. typhimurium ranging from 10(2) to 10(9)CFU/ml. Detection limits of 5x10(3) CFU/ml, 10(5) CFU/ml and 10(7) CFU/ml were obtained for sensors with the size of 2 mmx0.4 mmx15 microm, 5 mmx1 mmx15 microm and 25 mmx5 mmx15 microm, respectively. Good agreement between the measured number of bound bacterial cells (as measured by scanning electron microscopy (SEM)) and frequency shifts was obtained.

Rapid purity check method for susceptibility testing of M. tuberculosis complex with the MGIT 960 system

The Bactec MGIT 960 system is a rapid and reliable automated method for drug susceptibility testing of Mycobacterium tuberculosis complex (MTBC) that yields a high percentage of agreement with the standard method. The microscopic cord morphology of M. tuberculosis in liquid medium is characteristic, and readily differentiates MTBC from nontuberculous mycobacteria (NTM). The goals of this study were to describe the microscopic and macroscopic growth morphology of MTBC in antimicrobial-containing MGIT tubes and to evaluate the usefulness of the growth appearance during purity checking. The macroscopic cotton wool-like appearance of MTBC isolates in isoniazid (INH), streptomycin (SM), rifampin (RMP), and ethambutol (EMB)-containing tubes was observed in 97, 90, 93, and 71% of the isolates, respectively. The percentage of typical cord, loose, or frayed rope microscopic features in smears prepared from MTBC-positive cultures of INH, SM, RMP, and EMB-containing tubes was 96, 86, 97, and 71%, respectively. The sensitivity of the macroscopic morphology for predicting the purity of drug-containing MGIT tubes was 93%, while the microscopic morphology predicted the purity with a sensitivity rate of 92%. We found that simply examining the macroscopic morphology of the antimicrobial-containing MGIT tubes of drug-resistant MTBC isolates is useful in preventing false resistant results of susceptibility testing by the MGIT 960 system.

Synthesis and antimicrobial applications of 5,5′-ethylenebis[5-methyl-3-(3-triethoxysilylpropyl)hydantoin]

A novel, durable, long lasting, N-halamine siloxane monomer precursor, 5,5'-ethylenebis[5-methyl-3-(3-triethoxysilylpropyl)hydantoin] has been prepared and characterized by (1)H-NMR and FTIR for the purpose of functionalizing the surfaces of various materials. In this work, the precursor N-halamine moiety was attached by siloxane covalent bonding to surfaces of cotton fibers. Simulated laundering tests indicated that the chlorinated N-halamine structure could survive many repeated home launderings. The materials were rendered biocidal after exposure to oxidative halogen solutions, i.e. dilute household bleach. Once chlorinated, these materials were biocidal against Staphylococcus aureus and Escherichia coli. Upon loss of the halogen from either long-term use or consumption by the microbes on the surfaces, they could be simply recharged by further exposure to dilute bleach to regain biocidal activity.

Streptococcus suis meningitis with ventriculoperitoneal shunt infection and spondylodiscitis

Streptococcus suis is a zoonotic pathogen which causes meningitis, bacteremia, and endocarditis in pigs. Human infection is rare and often presents as meningitis with the sequela of permanent deafness and endocarditis. Previous cases were reported from pig-rearing countries such as Holland and Hong Kong. We report a 55-year-old bedridden man with S. suis meningitis complicated with ventriculoperitoneal shunt infection and lumbar spine spondylodiscitis. He presented with fever, delirium, neck stiffness, lower leg weakness and sudden onset hearing loss for several days. He was successfully treated with intravenous antibiotics, ventriculoperitoneal shunt replacement, lumbar spinal laminotomy and discectomy. Cerebrospinal fluid culture initially misidentified the organism as Streptococcus acidominimus, and S. suis was later identified by 16S rRNA sequencing. Misidentification of the microbiological findings may lead to a failure to correctly diagnose this disease. S. suis meningitis should be included in the differential diagnosis of patients with meningitis and sudden hearing loss.

Trends in fluoroquinolone resistance of Mycobacterium tuberculosis complex in a Taiwanese medical centre: 1995-2003

OBJECTIVES

Fluoroquinolones are being used more frequently for the treatment of multidrug-resistant (MDR) strains of Mycobacterium tuberculosis complex (MTB). This study was designed to determine the frequency of the emergence of fluoroquinolone-resistant strains in Taiwan and to assess whether this might be due to use of fluoroquinolones for treatment of patients with MDR or because of increased use of fluoroquinolones in the community for treatment of other infections. We also sought to determine whether there might be clonal spread of fluoroquinolone resistance.

METHODS

A total of 3497 clinical isolates of M. tuberculosis complex were obtained during 1995-2003, of which 141 were selected. They consisted of 62 isolates fully susceptible to four first-line drugs, 33 isolates resistant to rifampicin and isoniazid (MDR), and 46 isolates with a variety of any drug resistant patterns other than MDR (combination group). The MICs were determined for ciprofloxacin, ofloxacin and levofloxacin.

RESULTS

An increase in the MIC90 and rates of resistance to ciprofloxacin, ofloxacin and levofloxacin were noted only in the MDR group. The rates were higher among strains isolated between 1998-2003 compared with those obtained between 1995-1997 (rate of resistance, 20% versus 7.7%; MIC > or = 4 mg/L versus 1-2 mg/L). Among the 10 fluoroquinolone-resistant isolates, five (50%) possessed mutations other than S95T in the gyrA gene. No gyrB mutation was found in any of the clinical isolates.

CONCLUSIONS

These findings suggest that fluoroquinolone resistance is the result of treatment of patients with MDR strains rather than from use in the general community in Taiwan. The emergence of fluoroquinolone resistance among MDR strains reinforces the need for routine fluoroquinolone susceptibility testing whenever these drugs might be used.

Discordant molecular characterization results in a Mycobacterium avium complex strain isolated from an AIDS patient

This report describes an unusual strain of Mycobacterium avium complex isolated from the sputum of an immunocompromised AIDS patient, which did not react with the MAC probe of the BDProbe Tec system, but was identified as Mycobacterium intracellulare by 16S rRNA gene sequencing. Its PCR restriction-enzyme analysis pattern was compatible with an allelic variant of M. avium. It was scotochromogenic, slow-growing and phenotypically identified as Mycobacterium scrofulaceum. Its clinical significance is not certain.

Phylogenetic analysis of classical swine fever virus in Taiwan

Two envelope glycoprotein (Erns and E2) regions of the classical swine fever virus (CSFV) were amplified by RT-PCR and sequenced directly from 158 specimens collected between 1989 and 2003 in Taiwan. Phylogenetic analysis of the two regions revealed a similar tree topology and the Erns region provided better discrimination than the E2 region. One hundred and fifteen isolates out of the 158 isolates were clustered within subgroup 2.1 (further classified as 2.1a and 2.1b) and 2.2, which were considered to be likely of the introduced strains, whereas the remaining 43 isolates were clustered within subgroup 3.4 and were considered to be of the endemic strains. The subgroup 2.1a viruses were first detected in 1994 and predominated from 1995 onwards. However, subgroup 3.4 viruses were prevalent in the early years, not being isolated after 1996. We have observed a dramatic switch in genotype from subgroup 3.4 to 2.1a. The subgroup 2.1a isolates are closely related to the Paderborn and Lao isolates, whereas 2.1b isolates have a close relationship to the Chinese Guangxi isolates. The phylogenetic tree of 27 CSFV sequences based on the complete envelope glycoprotein gene (Erns-E2) displayed better resolution than that based on the complete open reading frame.

Preservation of clinical isolates of Mycobacterium tuberculosis complex directly from MGIT culture tubes

Preservation of M. tuberculosis complex strains isolated from clinical specimens is important for epidemiological investigations related to tuberculosis. In this study the efficacy of preservation was evaluated by calculating the recovery rate of preserved strains, with various patterns of resistance, after periods of storage and subculture. The recovery rates from strains preserved in enriched solid medium were >90% for storage periods <or=6 yr. However, this procedure for storing mycobacteria is time-consuming, labor-intensive, and impractical for routine use in a clinical laboratory setting. This study shows that recovery rates for strains preserved directly from MGIT fluids are satisfactory for storage periods <or=2 yr. No significant difference in viability was observed within 3 categories of drug resistance: (i) all-susceptible, (ii) multi-drug resistant (MDR), and (iii) a combination of other patterns of resistance. Preserving clinical M. tuberculosis strains directly from MGIT culture fluid fits easily into laboratory routine and is feasible for use in a clinical laboratory setting.

Correlation between pyrazinamide activity and pncA mutations in Mycobacterium tuberculosis isolates in Taiwan

A total of 76 clinical Mycobacterium tuberculosis isolates from Taiwan were tested for pyrazinamidase activity, pyrazinamide susceptibility, and pncA mutations. Frequency of resistance to PZA rose with increases in resistance to first-line drugs. Of 17 pyrazinamide-resistant strains, 7 (3 of which had not been previously described) possessed mutations in the pncA gene.

Use of MGIT 960 for rapid quantitative measurement of the susceptibility of Mycobacterium tuberculosis complex to ciprofloxacin and ethionamide

OBJECTIVES

Tentative standards for testing MICs for Mycobacterium tuberculosis include agar dilution and the BACTEC method. However, the conventional agar dilution method requires 3-5 weeks to complete; whereas BACTEC, although a rapid test, involves the use of radioisotopes. In contrast, the MGIT 960 system uses a fluorescence quenching based oxygen sensor that can be read automatically. This system is not only robust, safe and simple, but has been validated for susceptibility tests of first-line antituberculous agents.

METHODS

We evaluated 46 clinical strains of M. tuberculosis isolated from patients admitted to Kaohsiung Veterans General Hospital. Testing of MICs of ciprofloxacin and ethionamide was carried out by MGIT 960 and compared with the agar dilution method.

RESULTS

Good agreement was found between MGIT 960 and agar dilution. The greatest concordance between the agar dilution and MGIT assay at +/-1 and +/-2 dilution was 80.4% and 97.8% for ciprofloxacin, and 82.6% and 93.5% for ethionamide, respectively.

CONCLUSION

MGIT 960 was found to be comparable to the current NCCLS standard method, agar dilution, and has the advantage of being rapid (obtaining results within 5-17 days, average 8.9 days) and easy to achieve standardization.

Cytokeratin-19 associated with apoptosis and chemosensitivity in human cervical cancer cells

Cytokeratins are one group of intermediate filament proteins responsible for the integrity of cell structure, and have been recently reported to play a role in conferring a drug resistance phenotype. MAb Cx-99 is a monoclonal antibody exhibiting the specificity toward its corresponding antigen which was recently identified as the cytokeratin-19 protein. In the present study, we found that the level of cytokeratin-19 in cervical cancer cells could be decreased by incubation of cancer cells with MAb Cx-99. The reduction of cytokeratin-19 level had a killing effect on cervical carcinoma SIHA and HeLa S3 cell lines. The DNA ladder pattern, convoluted nuclei and blebbing morphology were observed with these cells after exposure to MAb Cx-99 for 72 h, suggesting that the cytotoxic mechanism of reduced cytokeratin-19 was mediated by induction of apoptosis. Moreover, the MAb Cx-99 treatment could increase the cytotoxicities of cancer chemotherapeutic agents such as cisplatin and vinblastine to both cervical carcinoma cell lines. The LD80 values were at least 15-fold reduced when cancer cells were treated with cisplatin or vinblastine in the presence of MAb Cx-99. These results suggest that the functional role of cytokeratin-19 was associated with the apoptosis prevention and drug resistance of cervical cancer cells.