Detection of leptospires in urine by polymerase chain reaction

Comparative seropositivity of Listeria monocytogenes in the serum of pregnant women with and without a history of abortion by serological and culture methods

OBJECTIVE

Listeria monocytogenes is a major cause of miscarriage and postpartum infections in infant. Determining antibody levels against listeriolysin O can be valuable for diagnosing both invasive listeriosis and febrile gastroenteritis. However, serological methods that detect antibodies against incomplete forms of listeriolysin O can be more specific. The objective of this study was to identify (Listeria monocytogenes) in the serum of pregnant women using serological and culture methods.

METHODS

Clinical samples (120 cases) were collected from pregnant women with a gestational age of less than 20 weeks. Diagnosis of Listeria monocytogenes was conducted using culture methods to identify anti-Listeria antibodies. Statistical analysis of the results was conducted using IBM SPSS Statistics version 23.0 (New York, USA), Pearson's Chi Square and fisher tests.

RESULTS

The number of positive samples by culture and ELISA was 24.16% (29) and 28.3% (34), respectively. Out of the 29 positive sample by the culture method, 10 individuals had no abortion history, 16 and 3 individuals had 1 and 2 abortions and no sample had 3 abortions. Maybe, the more abortions a person has had, the less likely they are to be infected. In the Enzyme Linked Immuno-Sorbent Assay (ELISA) method, 13 individuals tested positive for both IgG and IgM antibodies and 38 individuals tested negative. Additionally, among the positive individuals with 1, 2, and 3 miscarriages, 0, 17, and 3 people were positive for the IgG antibody and 0, 18, and 3 individuals were positive for the IgM antibody. The analysis results indicated that there was no significant relationship between culture and abortion history (p = 0.316), IgG ELISA and history of miscarriage (p = 0.672) and IgM ELISA and history of miscarriage (p = 0.552).

CONCLUSION

There was no significant relationship between infection with Listeria monocytogenes and abortion (p ⩾ 0.05) in our samples. These results should be interpreted with caution due to the limitation of our small sample size.

Evaluation of diagnostic accuracy of loop-mediated isothermal amplification method (LAMP) compared with polymerase chain reaction (PCR) for Leptospira spp. in clinical samples: a systematic review and meta-analysis

Loop-mediated isothermal amplification (LAMP) test is widely used in molecular diagnostics as a point-of-care technique alternative to traditional PCR especially in resource-limited countries. LAMP has been recently used to diagnose leptospirosis. Therefore, we undertook a systematic review and meta-analysis to compare the accuracy of LAMP with PCR in the diagnosis of leptospirosis. Sixty-one studies were extracted from three international databases and analyzed throughout using the PRISMA guideline. The pooled sensitivity of LAMP and PCR technique was 0.80 (95% CI: 0.58-0.90) and 0.54 (95% CI: 0.35-0.67) respectively indicating that LAMP is more sensitive than PCR. The Q* value of LAMP and PCR-based technique is 274.61 and 397.95, respectively. Among the analyzed studies, significant heterogeneity was observed where I² is 90.90% for LAMP-based and 86.18% for PCR-based. Our study suggests that LAMP has better diagnostic accuracy than PCR. However, future work should be carried out to reduce heterogeneity as well as to improve and develop effective intervention strategies.

Update on molecular diagnosis of human leptospirosis

Background

Leptospirosis, caused by pathogenic Leptospira spp., is a widespread zoonotic disease worldwide. Early diagnosis is required for proper patient management and reducing leptospirosis morbidity and mortality.

Objective

To summarize current literature regarding commonly used and new promising molecular approaches to Leptospira detection and diagnostic tests of human leptospirosis.

Method

The relevant articles in Leptospira and leptospirosis were retrieved from MEDLINE (PubMed) and Scopus.

Results

Several molecular techniques have been developed for diagnosis of human leptospirosis. Polymerase chain reaction-based techniques targeting on either lipL32 or 16S rRNA (rrs) gene are most commonly used to detect leptospiral DNA in various clinical specimens. Whole blood and urine are recommended specimens for suspected cases in the first (acute) and the second (immune) phases, respectively. Isothermal amplification with less expensive instrument is an alternative DNA detection technique that may be suitable for resource-limited laboratories.

Conclusion

Detection of leptospiral DNA in clinical specimens using molecular techniques enhances sensitivity for diagnosis of leptospirosis. The efficient and robust molecular detection especially in the early leptospiremic phase may prompt early and appropriate treatment leading to reduced morbidity and mortality of patients with leptospirosis.

Study protocol: characterising the clinical, epidemiological and aetiological aspects of leptospirosis in Sri Lanka: a hospital based clinico-epidemiological study

INTRODUCTION

Sri Lanka has one of the highest incidences of leptospirosis worldwide. We hypothesised that different geographical locations and patient context will have a distinct molecular epidemiology of leptospirosis, based on microgeographical characteristics related to regiona-specific Leptospira predominance. Our objective is to characterise the clinical, epidemiological and molecular aspects of leptospirosis in Sri Lanka to understand disease progression, risk factors and obtain isolates of Leptospira.

METHODS AND ANALYSIS

We designed a multicentre prospective study in Sri Lanka to recruit undifferentiated febrile patients and conduct follow-ups during hospital stays. Patients will be recruited from outpatient departments and medical wards. This study will be conducted at two main sites (Anuradhapura and Peradeniya) and several additional sites (Awissawella, Ratnapura and Polonnaruwa). Blood and urine will be collected from patients on the day of admission to the ward or presentation to the outpatient department. Bedside inoculation of 2-4 drops of venous blood will be performed with Ellinghausen-McCullough-Johnson-Harris (EMJH) semisolid media supplemented with antibiotics. Regionally optimised microscopic agglutination test, culture and qPCR-evidence will be performed to confirm the presence of Leptospira in blood which in turn will confirm the presence of disease. Whole genome sequencing will be carried out for all isolates recovered from patients. Multilocus sequence typing (MLST) will be used for the genotyping of new isolates. Sri Lankan isolates will be identified using three published MLST schemes for Leptospira.

ETHICS AND DISSEMINATION

Ethical clearance for the study was obtained from Ethics Review Committees (ERC), Medicine and Allied Sciences (FMAS), Rajarata University of Sri Lanka (RUSL) and University of Peradeniya. All genomic data generated through this project will be available at GenBank. Anonymised data will be deposited at the ERC, FMAS, RUSL.

Microbial Activity and Habitability of an Antarctic Dry Valley Water Track

Water tracks in the Antarctic Dry Valleys are dark linear features of increased soil moisture that flow downslope over the spring and summer, providing a source of moisture in a cold-arid desert. They are typically sourced from melting snow, ground ice, and deliquescence (Levy et al., 2011 ). This research presents the first in-depth study of the activity potential and diversity of microbial communities of Antarctic water tracks. We investigated whether these water track soils are more habitable to microbial communities by ascertaining the differences in diversity, total and culturable cell counts, and microbial respiratory activity in water track soils compared with the adjacent dry soils in Pearse Valley. Total cell counts ranged from 1.47 × 10³ to 4.17 × 10⁵ cells/g dry weight soil. Water track soils had higher total and culturable biomass, in addition to higher microbial activity at 5° and -5°C, compared with adjacent dry soils. Microbial respiration was positively correlated with soil moisture content, but total cell counts and plate counts were not. Surprisingly, microbial community composition did not differ between wet and dry soil communities, and was not related to soil moisture content. The microbial community composition instead appeared to differ spatially based on location and depth. Overall, the data suggest that cold water tracks are more habitable than the surrounding cold-arid soils. Our results suggest that recurring slope lineae, which are dark linear features that grow downslope on Mars over the spring and summer, where liquid water might be a recurring phenomenon, could be sites of astrobiological potential.

An efficient and cost-effective method for purification of small sized DNAs and RNAs from human urine

Urine holds great promise as a non-invasive sampling method for molecular diagnostics. The cell-free nucleic acids of urine however are small, labile, and difficult to purify. Here an efficient method for the purification of these nucleic acids is presented. An empirically derived protocol was devised by first identifying conditions that allowed recovery of a 100 base pair (bp) DNA, followed by optimization using a quantitative polymerase chain reaction (qPCR) assay. The resulting method efficiently purifies both small sized DNAs and RNAs from urine, which when combined with quantitative reverse transcription PCR (qRTPCR), demonstrably improves detection sensitivity. Fractionation experiments reveal that nucleic acids in urine exist both in the cell-free and cellular fraction, roughly in equal proportion. Consistent with previous studies, amplicons > 180bp show a marked loss in PCR sensitivity for cell-free nucleic acids. Finally, the lysis buffer developed here also doubles as an effective preservative, protecting against nucleic acid degradation for at least two weeks under simulated field conditions. With this method, volumes of up to 25ml of whole urine can be purified in a high-throughput and cost-effective manner. Coupled with its ability to purify both DNA and RNA, the described method may have broad applicability for improving the diagnostic utility of urine, particularly for the detection of low abundant targets.

Design, implementation, and interpretation of amplification studies for prion detection

Amplification assays for transmissible spongiform encephalopathies have been in development for close to 15 years, with critical implications for the postmortem and antemortem diagnosis of human and animal prion diseases. Little has been published regarding the structured development, implementation and interpretation of experiments making use of protein misfolding cyclic amplification (PMCA) and real time quaking-induced conversion (RT-QuIC), and our goal with this Perspectives manuscript is to offer a framework which might allow for more efficient expansion of pilot studies into diagnostic trials in both human and animal subjects. This framework is made up of approaches common to diagnostic medicine, including a thorough understanding of analytical and diagnostic sensitivity and specificity, an a priori development of amplification strategy, and an effective experimental design. It is our hope that a structured framework for prion amplification assays will benefit not only experiments seeking to sensitively detect naturally-occurring cases of prion diseases and describe the pathogenesis of TSEs, but ultimately assist with future endeavors seeking to use these methods more broadly for other protein misfolding disorders, including Alzheimer's and Parkinson's disease.

[Diagnosis of leptospirosis in dogs]

Rapid confirmation of the diagnosis leptospirosis is important in order to apply appropriate treatment; in addition, infected dogs are a zoonotic risk. Culture and isolation of living leptospires from blood, urine, or tissues is considered the reference standard of diagnosis. However, sensitivity are low, and leptospires require weeks to months to grow. Therefore, diagnosis of leptospirosis is most commonly based on antibody testing or the detection of Leptospira spp. DNA by PCR. Microscopic agglutination test (MAT) is currently still the recommended confirmatory test for canine leptospirosis, despite its numerous limitations (e. g., negative results in early infection, positive results due to vaccine-associated antibodies). ELISA can differentiate between IgG and IgM antibodies and thus, discriminate current infections from previous vaccination or exposure. Point-of-care tests and in-house-PCR tests have recently been developed for use in private practice allowing easy and immediate diagnosis. However, only few data on sensitivity and specificity of these tests exist so far. A reliable diagnosis can only be established in case of a positive PCR result or a fourfold titre increase in MAT.

Combined antibody and DNA detection for early diagnosis of leptospirosis after a disaster

Early diagnosis based on laboratory confirmation is essential for managing leptospirosis. This study investigated the effectiveness of a novel method of detecting leptospirosis that combines measurement of anti-Leptospira antibodies by the microscopic agglutination test (MAT), enzyme-linked immunosorbent assay (ELISA), and immunochromatographic test (ICT) and leptospiral DNA by loop-mediated isothermal amplification (LAMP) and real-time PCR in plasma and 2 types of urine pellets. Of 113 suspected cases, 68.1%, 76.1%, and 60.2% were positive by MAT, ELISA, and ICT, respectively. Real-time PCR using DNA purified from urine pellets collected by low-speed centrifugation yielded positive signals for patients in late acute as well as early phase who were positive by LAMP using plasma DNA or urine pellets. Among antibody-negative patients, 9.5% were positive by DNA detection. These findings indicate that the leptospirosis detection rate is increased by combining antibody and DNA detection, providing a new tool for timely diagnosis of infection.

Interlaboratory and between-specimen comparisons of diagnostic tests for leptospirosis in sheep and cattle

A study was performed to investigate interlaboratory test agreement between a research and a commercial veterinary diagnostic laboratory on blood and urine samples, and to investigate test agreement between blood, urine, and kidney samples (research laboratory) for leptospirosis diagnosis. Samples were sourced from 399 sheep and 146 beef cattle from a local abattoir. Interlaboratory agreement for real-time quantitative polymerase chain reaction (qPCR) results on urine samples was almost perfect (kappa = 0.90), despite the use of different amplification targets (DNA gyrase subunit B gene vs. 16s ribosomal RNA gene), chemistries (SYTO9 vs. TaqMan probe), and pre-PCR processing. Interlaboratory agreement for microscopic agglutination test (MAT) positivity was almost perfect (kappa = 0.93) for Leptospira borgpetersenii serovar Hardjo subtype Hardjobovis (Hardjobovis) but moderate (kappa = 0.53) for Leptospira interrogans serovar Pomona (Pomona). Among animals that had different titers recorded, higher Hardjobovis and lower Pomona titers were reported by the commercial laboratory than by the research laboratory (P < 0.005). These interlaboratory comparisons can assist researchers and diagnosticians in interpreting the sometimes discrepant test results. Within the research laboratory, the comparison of qPCR results on urine and kidney showed almost perfect agreement (kappa = 0.84), suggesting that the qPCR on these 2 specimens can be used interchangeably. The agreement between MAT positivity and urine and kidney qPCR results was fair (kappa = 0.32 and kappa = 0.33, respectively). However, the prevalence ratio of urine and kidney qPCR positivity in Hardjobovis-seropositive versus Hardjobovis-seronegative sheep indicated that Hardjobovis seropositivity found in sheep may be able to predict shedding or renal carriage.

Microbial and physicochemical parameters associated with Legionella contamination in hot water recirculation systems

Hot water recirculation systems (HWRS) in hotels and nursing homes, which are common in countries such as Spain, have been related to outbreaks of legionellosis. To establish the relationships of microbial and physicochemical parameters, especially protozoa, with the occurrence of Legionella in HWRS, 231 samples from hotels and nursing homes were analysed for Legionella, protozoa, heterotrophic plate counts (HPC) at 22 and 37 °C, Pseudomonas, metals, temperature and others. Legionella pneumophila was the dominant species isolated, and 22 % were sg. 1. The sampling method became particularly important in order to define which factors were involved on the occurrence of Legionella. Results showed that the bacteria and the accompanying microbiota were more abundant in the first flush water whose temperature was lower. The bacteria occurred in those samples with high HPC and were inversely correlated with high temperatures. Multivariate regression showed that a concentration above 1 × 10(5) CFU/100 mL of HPC at 37 °C, Fe above 0.095 ppm and the presence of protozoa increased significantly the risk of Legionella colonization, while univariant regression showed that the presence of Cu above 0.76 ppm and temperature above 55 °C diminished it. Therefore, to reduce the risk associated with Legionella occurrence in HWRS these parameters should be taken into consideration.

Evaluation of pathogenic serovars of Leptospira interrogans in dairy cattle herds of Shahrekord by PCR

BACKGROUND AND OBJECTIVES

Leptospirosis is an important zoonotic disease caused by Leptospira interrogans. Leptospirosis leads to economical losses in dairy farm industry. The objective of this study was to evaluate the pathogenic serovars of Leptospira interrogans in dairy cattle herds of Shahrekord by PCR.

MATERIALS AND METHODS

Two hundred samples (100 urine and 100 blood) were collected from 100 cows randomly and delivered to the laboratory. Samples were stored at -20 °C. DNA was extracted and purified from the plasma and urine samples and concentrated on diatoms in the presence of guanidine thiocyanate (GuSCN). PCR products were detected and identified as Leptospira by ilumination of the expected size of DNA bands after staining of the agarose gel with ethidium bromide gels. PCR products were purified and sequenced.

RESULTS

The results showed that 28% of urine samples and 23% of plasma samples were contaminated. The major serotypes were Icterohaemorrhagiae (50%) and Pomona (37.5%). The urine samples of 17 cows were positive for Leptospira without positive plasma samples. This indicated that these cows are reservoirs in dairy herds of Shahrekord and dangerous for human health. The plasma samples of twelve cows were positive for Leptospira without positive urine samples.

CONCLUSIONS

Leptospira serotypes can be maintained in relatively dry regions and must be considered when dealing with leptospirosis in dairy farms of Shahrekord and human health.

Biochemical and mutational studies of the Bacillus cereus CECT 5050T formamidase support the existence of a C-E-E-K tetrad in several members of the nitrilase superfamily

Formamidases (EC 3.5.1.49) are poorly characterized proteins. In spite of this scarce knowledge, ammonia has been described as playing a central role in the pathogenesis of human pathogens such as Helicobacter pylori, for which formamidase has been shown to participate in the nitrogen metabolic pathway. Sequence analysis has revealed that at least two different groups of formamidases are classified as EC 3.5.1.49: on the one hand, the derivatives of the FmdA-AmdA superfamily, which are the best studied to date, and on the other hand, the derivatives of Helicobacter pylori AmiF. Here we present the cloning, purification, and characterization of a recombinant formamidase from Bacillus cereus CECT 5050T (BceAmiF), the second member of the AmiF subfamily to be characterized, showing new features of the enzyme further supporting its relationship with aliphatic amidases. We also present homology modeling-based mutational studies confirming the importance of the Glu140 and Tyr191 residues in the enzymatic activities of the AmiF family. Moreover, we can conclude that a second glutamate residue is critical in several members of the nitrilase superfamily, meaning that what has consistently been identified as a C-E-K triad is in fact a C-E-E-K tetrad.

Prevalence of microsporidia in an indigenous Orang Asli community in Pahang, Malaysia

Microsporidia are ubiquitous parasites thought to be closely related to fungi. Their presence in the environment means that humans are frequently exposed to infection. Stool samples were collected from 151 indigenous villagers from the eastern state of Pahang in 2005. The samples were concentrated with water-ether sedimentation, stained with modified trichrome stain and examined under oil-immersion microscopy. Thirty-two specimens (21.2%) were positive for microsporidia. Microsporidia were observed as ovoid or rounded ovoid shapes measuring approximately 1mum, with a bright pink outline containing a central or posterior vacuole. PCR amplification with specific primers on microscopy-positive specimens amplified Encephalitozoon intestinalis DNA from five of the ten specimens used.

Detection of pathogenic leptospires in urine from naturally infected cattle by nested PCR

A nested polymerase chain reaction (PCR) using primers from the LipL32 sequence of Leptospira spp. was used to detect shedding of pathogenic leptospires in urine from naturally infected cattle. Amplicons (497bp) were obtained from 21 pathogenic reference serovars belonging to four species (L. interrogans, L. borgpetersenii, L. santarosai, L. kirschneri). DNA was amplified from 26/30 urine samples taken from cattle with suspected leptospirosis and from leptospires cultivated from 10 of these samples. The limit of detection of DNA in the clinical samples was 200pg and the nested PCR detected all pathogenic reference serovars of Leptospira spp. tested. No PCR products were amplified using DNA from other common bacterial species from the bovine urogenital tract or urine, or from the non-pathogenic L. biflexa Andamana serovar. The nested PCR exhibited high specificity and sensitivity for detection of pathogenic serovars in urine from cattle.

Isolation and characterization of Leptospira interrogans from pigs slaughtered in São Paulo State, Brazil

With the aim of isolating Leptospira spp., blood serum, kidney, liver and genital tract of 137 female swine (40 sows and 97 gilts) and also urine samples from 22 sows were collected in a slaughterhouse in the State of São Paulo, from April 2003 to August 2004. Four isolates were obtained from animals that presented microagglutination test (MAT) titers ≥ 100 for the serovar Pomona and one was obtained from an animal negative by MAT in which Leptospira was isolated from the liver and reproductive tract. The presence of leptospiral DNA was investigated by PCR, and positive results were found in kidneys of 11 females, liver of two, genital tract of two and urine of one of them. Nephrosis, interstitial multifocal nephritis, moderate to severe changing, hyalines cylinders and hemorrhagic focuses, hepatic and uterine horns congestion were histological lesions observed in higher frequency in animals positive for leptospira. The silver impregnation (Warthin Starry) confirmed the presence of spirochetes in renal tubules of four females with positive leptospira cultures from kidneys. The serogroup of the five isolates was identified as Pomona by cross agglutination with reference polyclonal antibodies. Molecular characterization of the isolates was carried out by variable-number tandem-repeats analysis. All the isolates revealed a pattern distinct from the L. interrogans Pomona type strain, but identical to a previously identified pattern from strains isolated in Argentina belonging to serovar Pomona.

Crystallization and preliminary crystallographic studies of the recombinant dihydropyrimidinase from Sinorhizobium meliloti CECT4114

Dihydropyrimidinases are involved in the reductive pathway of pyrimidine degradation, catalysing the hydrolysis of 5,6-dihydrouracil and 5,6-dihydrothymine to the corresponding N-carbamoyl beta-amino acids. This enzyme has often been referred to as hydantoinase owing to its industrial application in the production of optically pure amino acids starting from racemic mixtures of 5-monosubstituted hydantoins. Recombinant dihydropyrimidinase from Sinorhizobium meliloti CECT4114 (SmelDhp) has been expressed, purified and crystallized. Crystallization was performed using the counter-diffusion method with capillaries of 0.3 mm inner diameter. Crystals of SmelDhp suitable for data collection and structure determination were grown in the presence of agarose at 0.1%(w/v) in order to ensure mass transport controlled by diffusion. X-ray data were collected to a resolution of 1.85 A. The crystal belongs to the orthorhombic space group C222(1), with unit-cell parameters a = 124.89, b = 126.28, c = 196.10 A and two molecules in the asymmetric unit. A molecular-replacement solution has been determined and refinement is in progress.

Rapid Diagnosis of Brucella Epididymo-Orchitis by Real-Time Polymerase Chain Reaction Assay in Urine Samples

PURPOSE

We studied the diagnostic yield of a real-time polymerase chain reaction assay in urine samples for the rapid diagnosis of brucella epididymo-orchitis compared to that of conventional microbiological techniques.

MATERIALS AND METHODS

We used an SYBR Green I LightCycler based real-time polymerase chain reaction to retrospectively study 10 urine samples from patients with Brucella epididymo-orchitis. The assay amplifies a 223 bp sequence of a gene that codes for the synthesis of an immunogenetic membrane protein specific for Brucella genus (BCSP31). After amplifying this 223 bp sequence we performed melting curve analysis to verify the specificity of polymerase chain reaction products.

RESULTS

Brucella melitensis was isolated from blood cultures in 9 cases (90%). Wright's seroagglutination was negative or inconclusive in 30% of cases. Brucella was isolated from urine in only 1 case, whereas real-time polymerase chain reaction assay in urine was positive in 9 (90%). Also, results were available in 4 hours, whereas mean time to availability of the final blood culture results was 5.8 days (range 4.5 to 7).

CONCLUSIONS

SYBR Green I LightCycler based real-time polymerase chain reaction assay in urine samples is highly sensitive and specific, and easy to perform. It could provide the clinician with results in less than 5 hours. The technique could be a practical and useful tool for the rapid diagnosis of genitourinary complications of human brucellosis.

Detection and differentiation between pathogenic and saprophytic Leptospira spp. by multiplex polymerase chain reaction

A multiplex polymerase chain reaction (PCR) was developed for diagnosing leptospirosis and differentiating pathogenic and saprophytic leptospires. Specific primers were designed to amplify 23S rDNA from pathogenic Leptospira and saprophytic Leptospira spp. PCR products from 27 pathogenic and 5 (including 1 intermediate) saprophytic serovars were 615 and 316 base pairs (bp), respectively. After the restriction enzyme's digestion of PCR products, the fragments by SacI of pathogenic serovars and by PstI of saprophytic serovars were 339 and 276 bp and 202 and 114 bp, respectively. The PCR primers enabled amplification of DNA from L. meyeri serovar Ranarum as a pathogenic Leptospira spp. The PCR assay could detect 1 to 2 cells of leptospires and not amplify DNA from other 18 bacterial species. The sensitivity and specificity of this PCR in rat kidney, using isolation as gold standard, were 98.6% and 100%, respectively. The most appropriate sample preparation of blood for detecting DNA was buffy coat. Among the sample preparations from 7 laboratory-confirmed leptospirosis cases, leptospiral DNA was detected in all 7 buffy coat preparations, whereas leptospiral DNA was detected in only 3 plasma or serum samples. The PCR assay may be useful as a diagnostic tool for leptospirosis.

Evaluation of LSSP-PCR for identification of Leptospira spp. in urine samples of cattle with clinical suspicion of leptospirosis

We evaluated the use of low-stringency single specific primer PCR (LSSP-PCR) for genetically typing Leptospira directly from urine samples of cattle with clinical suspicion of leptospirosis. Urine samples obtained from 40 cattle with clinical suspicion of leptospirosis were amplified by specific PCR using the following primers: Internal 1/Internal 2 and G1/G2. The internal primers were designed from the gene sequence of the outer membrane lipoprotein Lip32 from Leptospira kirschneri, strain RM52. The PCR products were amplified with these two pairs of primers, which had approximately 497 and 285bp, respectively, and were subsequently used as a template for LSSP-PCR analysis. The genetic signatures from the leptospires which were present in the urine samples allowed us to make a preliminary identification of the leptospires by comparing the LSSP-PCR profiles obtained directly from urine samples with those from reference leptospires. The LSSP-PCR profiles obtained with the Internal 1 primer or with the G1 primer allowed the grouping of the leptospires into serogroups. LSSP-PCR was found to be a useful and sensitive approach capable of identifying leptospires directly from biological samples without the need for prior bacterial isolation. In conclusion, the LSSP-PCR technique may still be helpful in discriminating serogroups of Leptospira from different animal reservoirs, since the early identification of carrier animals and information on the shedding state are crucial to prevent the spread of leptospiral infection to other animals and humans.

Application of biochemical and polymerase chain reaction assays for identification of Campylobacter isolates from non-human primates

A multiplex polymerase chain reaction (PCR) assay was performed on 167 thermophilic campylobacters isolated from non-human primates. Samples were first identified by phenotypic methods resulting in 64 Campylobacter jejuni and 103 C. coli strains. Four strains identified biochemically as C. coli, were then determined to be C. jejuni by PCR. Comparison of methodologies showed that the main discrepancies were attributed to the hippurate hydrolysis test and sensitivity to cephalothin and nalidixic acid. Analysis of data showed that the application of phenotypic methods should be supplemented by a molecular method to offer a more reliable Campylobacter identification.

USO DE ESTREPTOMICINA NA ELIMINAÇÃO DA LEPTOSPIRÚRIA EM TOUROS (BOS TAURUS INDICUS) NATURALMENTE INFECTADOS PELO SOROVAR HARDJO

RESUMO O objetivo desse trabalho foi verificar a ação de marcas diferentes de estreptomicinas polivalentes para o tratamento da leptospirose bovina em dose única (25 mg de estreptomicina por kg de peso corpóreo). O trabalho foi realizado com 14 touros adultos sorologicamente reagentes para Leptospira interrogans sorovar Hardjo, com título mínimo de 800 e com cultivo positivo. Os animais foram separados em 2 grupos de acordo com a marca da estreptomicina utilizada no tratamento, grupo 1: estreptomicina A e grupo 2: estreptomicina B. Os bovinos controles não receberam nenhum tratamento. Foram obtidas amostras de sangue e urina dos animais tratados e controles nos dias -1, 0, 1, 2, 3, 5, 10, 15 e 25; considerando-se o dia do tratamento como dia 0. Na urina dos bovinos tratados e controle foi realizada a reação em cadeia da polimerase (PCR) e isolamento com inoculação em hamsters. Observou-se que a estreptomicina da marca A, em dose única de 25 mg/kg de peso corpóreo, conseguiu eliminar a leptospirúria no grupo de touros após 24h do tratamento. Já no grupo de touros tratados com a estreptomicina da marca B, foi constatado a leptospirúria entre 48h e 72h, após o tratamento. Em ambos os grupos tratados, a resposta sorológica apresentou uma variação da queda dos níveis dos títulos de anticorpos aglutinantes, sendo que embora a estreptomicina A tenha aparentemente apresentado um melhor desempenho quando comparada com as médias geométricas dos títulos do grupo tratado com a estreptomicina B as médias não diferiram entre si pelo Teste de Tukey (P > 0,05). Nos bovinos tratados a leptospirúria foi intermitente e a média geométrica dos títulos foi menor que a média geométrica dos títulos dos bovinos controles. A diferença do efeito da ação das diferentes marcas de estreptomicina está possivelmente na qualidade da matéria prima produzida pelos laboratórios.

Recommendations for the detection of Leptospira in urine by PCR

In the present study PCR was applied to detect leptospires in human urine. Several approaches for sample processing were evaluated to optimize the detection of leptospires in urine mixed with this bacterium. Furthermore, some changes in the composition of the reaction mix were studied. No amplification was observed in acidic urine, therefore neutralization of the sample immediately after collection is strongly recommended. PBS gave better results than Tris or NaOH as neutralizing reagents. Freezing and thawing of samples before processing yielded negative results. Elimination of epithelial cells, leukocytes and crystals by centrifugation at 3,000 rpm at room temperature increased sensitivity. In addition, both the washing step after collecting leptospires by centrifugation and the inclusion of 0.1% bovine serum albumin in the reaction mix minimized the interference of other inhibitory compounds. These modifications were useful to improve the detection of Leptospira in urine by PCR.

Rapid detection of Campylobacter coli, C. jejuni, and Salmonella enterica on poultry carcasses by using PCR-enzyme-linked immunosorbent assay

Contamination of retail poultry by Campylobacter spp. and Salmonella enterica is a significant source of human diarrheal disease. Isolation and identification of these microorganisms require a series of biochemical and serological tests. In this study, Campylobacter ceuE and Salmonella invA genes were used to design probes in PCR-enzyme-linked immunosorbent assay (ELISA), as an alternative to conventional bacteriological methodology, for the rapid detection of Campylobacter jejuni, Campylobacter coli, and S. enterica from poultry samples. With PCR-ELISA (40 cycles), the detection limits for Salmonella and Campylobacter were 2 x 10(2) and 4 x 10(1) CFU/ml, respectively. ELISA increased the sensitivity of the conventional PCR method by 100- to 1,000-fold. DNA was extracted from carcass rinses and tetrathionate enrichments and used in PCR-ELISA for the detection of Campylobacter and S. enterica, respectively. With PCR-ELISA, Salmonella was detected in 20 of 120 (17%) chicken carcass rinses examined, without the inclusion of an enrichment step. Significant correlation was observed between PCR-ELISA and cultural methods (kappa = 0.83; chi-square test, P < 0.001) with only one false negative (1.67%) and four false positives (6.67%) when PCR-ELISA was used to screen 60 tetrathionate enrichment cultures for Salmonella. With PCR-ELISA, we observed a positive correlation between the ELISA absorbance (optical density at 405 nm) and the campylobacter cell number in carcass rinse, as determined by standard culture methods. Overall, PCR-ELISA is a rapid and cost-effective approach for the detection and enumeration of Salmonella and Campylobacter bacteria on poultry.

Comparison of polymerase chain reaction assay, bacteriologic culture, and serologic testing in assessment of prevalence of urinary shedding of leptospires in dogs

OBJECTIVE

To compare results of polymerase chain reaction (PCR) testing of urine samples, serologic testing, and bacteriologic culture of urine to determine prevalence of urinary shedding of leptospires in dogs.

DESIGN

Serial case study.

ANIMALS

500 dogs evaluated serially without regard to health status.

PROCEDURE

Urine samples were examined via PCR assay and bacteriologic culture for leptospires. Blood samples were analyzed for antibodies against serovars canicola, bratislava, pomona, icterohemorrhagiae, grippotyphosa, and hardjo.

RESULTS

Titers > or = 1:100 against at least 1 serovar were detected in 104 (20.8%) dogs, and titers > or = 1:400 were detected in 41 (8.2%) dogs. High titers were detected most commonly to serovar grippotyphosa, followed by icterohemorrhagiae, canicola, pomona, bratislava, and hardjo. High titers to > 1 serovar were detected in 14 dogs. A positive PCR assay result was obtained in 41 (8.2%) dogs, only 9 of which had a titer > or = 1:100. Leptospires were not cultured from the urine of any dog. Only 4 dogs had clinical leptospirosis. Overall disease prevalence was 0.8% for the 6-month evaluation period. Compared with PCR assay, serologic testing for predicting shedding had a sensitivity of 22%, specificity of 79%, positive predictive value of 9%, and negative predictive value of 92%.

CONCLUSIONS AND CLINICAL RELEVANCE

Irrespective of health status, 8.2% of dogs were shedding pathogenic leptospires. Serologic testing was a poor predictor of urinary shedding. Clinically normal dogs that shed leptospires may pose a zoonotic risk to their owners.

Clinical application of a polymerase chain reaction assay for diagnosis of leptospirosis in dogs

OBJECTIVE

To evaluate the use of a polymerase chain reaction (PCR) assay on urine samples for diagnosis of leptospirosis in dogs.

DESIGN

Prospective case study.

ANIMALS

132 dogs with clinical signs suggestive of leptospirosis and 13 healthy dogs.

PROCEDURE

PCR testing was performed on urine samples to detect leptospiral DNA; results were compared with results of conventional criteria for the diagnosis of leptospirosis.

RESULTS

Leptospirosis was diagnosed in 8 dogs via established criteria; all these dogs had positive results of PCR assay, including 1 dog with positive results before seroconversion developed. A positive PCR assay result was also obtained in 16 dogs that did not have a confirmed diagnosis of leptospirosis. In the 8 dogs that had a confirmed diagnosis of leptospirosis, serovars pomona (n = 3 dogs), grippotyphosa (2), canicola (2), and bratislava (1) were identified serologically. The remaining 121 dogs all had a diagnosis other than leptospirosis or were healthy. For PCR testing on urine, sensitivity was 100%, specificity was 88.3%, positive predictive value was 33%, and negative predictive value was 100%.

CONCLUSIONS AND CLINICAL RELEVANCE

Positive PCR test results prior to seroconversion may have value in establishing an early diagnosis. Positive results in dogs that had signs consistent with leptospirosis despite failing to meet established criteria for leptospirosis raise questions regarding the sensitivity of serologic testing in diagnosis of leptospirosis. Serovars pomona, grippotyphosa, and canicola were most common.

A multiplex PCR for the detection of Brucella spp. and Leptospira spp. DNA from aborted bovine fetuses

Bovine brucellosis and leptospirosis are important causes of bovine abortion around the world. Both diseases can be serologically diagnosed, but many factors may cause false positive and negative results. Direct methods based on bacteriological isolation are usually employed, but they are difficult, time consuming and dangerous. Monoplex polymerase chain reaction (PCR) have been successfully described for the detection of Brucella spp. and Leptospira spp. Aiming at improvement in the direct diagnosis, a multiplex PCR (mPCR) for the detection of these agents in aborted bovine fetuses is described. The detection threshold of the mPCR was evaluated in experimentally contaminated bovine clinical samples using a conventional proteinase K/SDS or a boiling-based extraction protocols. The mPCR was applied to two groups of clinical samples: 63 episodes of bovine abortion and eight hamsters experimentally infected with Leptospira interrogans serovar pomona. Adopting microbiological isolation as reference, the test showed a sensitivity of 100% in both groups of clinical samples. Seven samples collected from bovine fetuses were Brucella spp. culture negative but showed positive results in mPCR. Regarding Leptospira spp. detection, similar results were observed in three bovine clinical samples. All hamsters infected with Leptospira were positive in both microbiological culture and mPCR. The boiling extraction protocol showed better results in some clinical samples, probably by the removal of PCR inhibitors by heat treatment. The high sensitivity, simplicity and the possibility of detection of both bacteria in a single tube reaction support the use of the mPCR described in the routine diagnosis.

Diagnosis of human leptospirosis by monoclonal antibody-based antigen detection in urine

Hybridomas secreting specific monoclonal antibodies (MAb) to all members of the genus Leptospira (clone LF9) and those that are specific only to the pathogenic species (clones LD5 and LE1) were produced. MAb LF9, which was immunoglobulin G1 (IgG1), reacted to a 38-kDa component of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated whole-cell lysates of all Leptospira spp., while MAb LD5 and MAb LE1, which were IgG1 and IgG2a, respectively, reacted to the 35- to 36-kDa components of all serogroups of the pathogenic species of LEPTOSPIRA: The MAb LD5 was used in a dot blot-enzyme-linked immunosorbent assay (dot-ELISA) for detecting Leptospira antigen in urine samples serially collected from two groups of patients diagnosed with leptospirosis, i.e., 36 clinically diagnosed patients and 25 Leptospira culture confirmed patients. Their serum samples were tested serologically by IgM Dipstick assay, indirect immunofluorescence assay (IFA), and/or microscopic agglutination test (MAT). Urine samples of 26 patients diagnosed with other illnesses and 120 healthy individuals served as controls. For the first group of patients, who had been ill for an average of 3.4 days before hospitalization, the IgM Dipstick test, IFA, and MAT were positive for 69.4, 70.0, and 85.7% of patients, while the Leptospira antigenuria tested by the MAb-based dot-ELISA was positive for 75.0, 88.9, 97.2, 97.2, and 100% of patients on days 1, 2, 3, 7, and 14 of hospitalization, respectively. All but 1 of 11 patients whose serum samples collected on the first day of hospitalization were IgM seronegative, were positive by urine antigen test on day 1. This is strong evidence that detection of antigen in urine can provide diagnostic information that could be useful in directing early therapeutic intervention. The MAT was positive in 10 of 12 patients (83.3%) of the 25 culture-positive Leptospira patients who had been ill for an average of 5.04 days before hospitalization, and the Leptospira antigen was found in 64.0, 84.0, 96.0, 100, 100, 100, and 100% of the patients' urine samples collected on days 1, 2, 3, 4, 5, 6, and 7 of hospitalization, respectively. Leptospira antigenuria was found in 3 of the 26 patients diagnosed with other illnesses and 1 of the 120 healthy controls. The reasons for this positivity are discussed. The detection of antigen in urine by the monoclonal antibody-based dot-ELISA has high potential for rapid, sensitive, and specific diagnosis of leptospirosis at a low cost.

Intestinal microsporidiosis: a current infection in HIV-seropositive patients in Portugal

Intestinal microsporidiosis is recognised as an important cause of opportunistic infections in immunocompromised patients, especially those with AIDS. Two species are implicated in diarrhoea and other gastrointestinal disease in HIV-infected patients: Enterocytozoon bieneusi and Encephalitozoon intestinalis. Diagnosis of gastrointestinal microsporidiosis was made by detecting spores of the parasite in stool specimens with Weber's modified trichrome stain and with some optical brightening agents such as UVITEX 2B or calcofluor white M2R. The identification of microsporidiosis at the species level was made using appropriate primers with PCR. The diagnosis of intestinal microsporidiosis is currently performed in the parasitology laboratory. In a study of 215 HIV-infected patients, conducted from 1996 to 1999 (approximately n = 60/year), we found a prevalence of spores of microsporidia of 51.5% (n = 31) in 1996, 14.0% (n = 5) in 1997 and 12.5% (n = 8) in 1998 and 42.8% (n = 25) in 1999. Using PCR we found that E. intestinalis was the only species responsible for the gastrointestinal symptoms in 49 patients with microsporidian spores (71%) and E. bieneusi in 29% (n = 20).

Leptospirosis

Leptospirosis is a worldwide zoonotic infection with a much greater incidence in tropical regions and has now been identified as one of the emerging infectious diseases. The epidemiology of leptospirosis has been modified by changes in animal husbandry, climate, and human behavior. Resurgent interest in leptospirosis has resulted from large outbreaks that have received significant publicity. The development of simpler, rapid assays for diagnosis has been based largely on the recognition that early initiation of antibiotic therapy is important in acute disease but also on the need for assays which can be used more widely. In this review, the complex taxonomy of leptospires, previously based on serology and recently modified by a genotypic classification, is discussed, and the clinical and epidemiological value of molecular diagnosis and typing is also evaluated.

Overview of the epidemiology, microbiology, and pathogenesis of Leptospira spp. in humans

Leptospirosis is probably the world's most widespread zoonosis. It remains underdiagnosed largely due to the broad spectrum of signs and symptoms attributable to this spirochetal pathogen. Leptospira spp. cause a diversity of diseases from flu-like illness to Weil's syndrome with multi-organ failure. Recent epidemics may herald a change in virulence or an alteration in the balance between humans and their interactions with other host species and the environment.

Detection and differentiation of Leptospira spp. serovars in bovine semen by polymerase chain reaction and restriction fragment length polymorphism

In view of the importance of venereal transmission of bovine leptospirosis, the objective of the present study was to apply the polymerase chain reaction (PCR) to 26 serovars of Leptospira interrogans, L. borgpetersenii, L. santarosai, L. noguchii and L. biflexa, to determine the detection threshold in semen samples and to evaluate the possibility of differentiation among serovars using 19 restriction endonucleases. The results showed that all serovars were amplified and the detection threshold in semen samples of a bull was 100 bacteria/ml. Using endonucleases we could classify the 26 serovars into eight groups. The present results show that PCR is a method of great potential for the detection of Leptospira spp. at bovine artificial insemination centers.

A comparison of three DNA extractive procedures with Leptospira for polymerase chain reaction analysis

Three DNA extraction methods were evaluated in this study: proteinase K followed by phenol-chloroform; a plant proteinase (E6870) followed by phenol-chloroform; and boiling of leptospires in 0.1 mM Tris, pH 7.0 for 10 min at 100 degrees C, with no phenol treatment. Every strain treated with proteinase K or E6870 afforded positive polymerase chain reaction (PCR) reaction. On the other hand, from five strains extracted by the boiling method, three did not feature the 849 bp band characteristic in Leptospira. We also evaluated by RAPD-PCR, DNAs from serovars isolated with proteinase K and proteinase 6870 with primers B11/B12. Each of the DNA samples provided PCR profiles in agreement with previous data. Moreover, the results with E6870 showed less background non-specific amplification, suggesting that removal of nucleases was more efficient with E6870. The limit for detection by PCR using Lep13/Lep14 was determined to be 10(2) leptospira, using the silver stain procedure.

Comparison of polymerase chain reaction assays with bacteriologic culture, immunofluorescence, and nucleic acid hybridization for detection of Leptospira borgpetersenii serovar hardjo in urine of cattle

OBJECTIVE

To compare sensitivity and specificity of various polymerase chain reaction (PCR) assays for detection of Leptospira borgpetersenii serovar hardjo in bovine urine and to compare results of the optimal PCR assay with results of immunofluorescence, nucleic acid hybridization, and bacteriologic culture.

ANIMALS

6 heifers.

PROCEDURE

Heifers were exposed to serovar hardjo type hardjo-bovis by conjunctival instillation of 10(6) leptospires on 3 successive days. Urine samples were collected before and after infection. Sensitivity and specificity of 5 PCR assays were compared, to determine the optimal assay for use with bovine urine samples. The optimal PCR assay was then compared with results of bacteriologic culture, nucleic acid hybridization, and immunofluorescence.

RESULTS

A PCR assay with the best combination of specificity (100%) and sensitivity (91%) was selected for comparison with the other diagnostic tests. Sensitivity for nucleic acid hybridization was 55%, whereas sensitivity for bacteriologic culture and immunofluorescence was 89 to 93%.

CONCLUSIONS AND CLINICAL RELEVANCE

Bacteriologic culture, PCR, and immunofluorescence were sensitive for detection of L borgpetersenii serovar hardjo type hardjo-bovis in urine specimens of cattle, but a single technique was not the most sensitive for each animal tested. Therefore, the use of 2 techniques in combination is warranted for maximal sensitivity for diagnosis.

Detection of leptospires in bovine semen by polymerase chain reaction

OBJECTIVE

In view of the considerable importance of venereal transmission of bovine leptospirosis, the objective of the present study was to compare the polymerase chain reaction (PCR), culture/isolation and serology to detect leptospire infection in bovine semen.

DESIGN

Blood for serologic examination and semen for bacterial culture and PCR were collected from 20 bulls at artificial insemination centres in Brazil. Each animal was sampled twice for serology.

RESULT

Forty-five percent (9/20) of the serum samples collected showed agglutinin titers to serovar hardjo in the first sample and 25% (5/20) had agglutinin titers to serovar hardjo in the second sample. Eighty percent (16/20) of semen samples were positive by PCR. Leptospires could not be isolated from any of the semen samples examined.

CONCLUSION

Polymerase chain reaction can be a method of great potential for the detection of leptospires at artificial insemination centres.

Rapid emergence of high-level resistance to quinolones in Campylobacter jejuni associated with mutational changes in gyrA and parC

Quinolone resistance in clinical isolates of Campylobacter jejuni in Sweden increased more than 20-fold at the beginning of the 1990s. Resistance to 125 microgram of ciprofloxacin per ml in clinical isolates was associated with chromosomal mutations in C. jejuni leading to a Thr-86-Ile substitution in the gyrA product and a Arg-139-Gln substitution in the parC product.

Differentiation of Campylobacter isolates on the basis of sensitivity to boiling in water as measured by PCR-detectable DNA

Differential sensitivity for the release of PCR-detectable genomic DNA upon boiling in water is reported for 45 Campylobacter jejuni and Campylobacter coli strains isolated in Egypt. All of the strains released PCR-detectable DNA when treated with proteinase K and sodium dodecyl sulfate. When DNA was extracted from these strains by boiling in water, nine (20%) of the strains were PCR negative or resistant to boiling, suggesting the presence of boiling-sensitive and boiling-resistant phenotypes.

Differentiation of Leptospira interrogans isolates by IS1500 hybridization and PCR assays

Genetic variability among Leptospira interrogans (sensu stricto) serovars was assessed by Southern blot hybridization and PCR analyses. The experiments used probes directed to sequences in a recently described insertion element, IS1500. Hybridization analysis showed that IS1500 was present on polymorphic fragments and that differences in these patterns could be used to identify serovars. Hybridization analysis was also useful in discriminating between serovar pomona type kennewicki isolates, making possible the identification of 15 previously unrecognized genetic groups. A PCR assay was developed in which the primers are positioned near the terminal inverted repeats of the element and directed outward. This assay yielded characteristic amplification patterns from isolates, allowing them to be identified. We applied these assays to several new animal isolates of L. interrogans from Nicaragua, which recently had an outbreak of human leptospirosis. Three groups of isolates were identified: one strain of serovar pomona type kennewicki and two genetically distinct groups of isolates which may be genetic intermediates between serovars canicola and portlandvere. The IS-based typing assays described should be useful for epidemiological analysis of leptospirosis.

Differentiation of pathogenic and non-pathogenic leptospires by means of the polymerase chain reaction

A polymerase chain reaction was carried out to detect pathogenic leptospires isolated from animals and humans in Argentina. A double set of primers (G1/G2, B64-I/B64-II), described before, were used to amplify by PCR a DNA fragment from serogroups belonging to Leptospira interrogans but did not allow to detect saprophytic strains isolated from soil and water (L. biflexa). This fact represents an advantage since it makes possible the differentiation of pathogenic from non-pathogenic leptospires in cultures. The sensitivity of this assay has been determined, allowing to detect just only 10 leptospires in the reaction tube. Those sets of primers generated either a 285 bp or 360 bp fragment, depending on the pathogenic strain.

Magnetic immuno capture PCR assay (MIPA): detection of Leptospira borgpetersenii serovar hardjo

Magnetic immuno PCR assay (MIPA) was developed for the rapid detection of leptospires excreted in urine samples (n = 59) collected from 35 experimentally infected cattle. The immunomagnetic separation of leptospires from inhibitors in frozen formalin fixed bovine urine prior to PCR detection resulted in a marked improvement on previous detection methods. MIPA is a rapid 5 step protocol requiring 70 mins preparation time prior to amplification, which consistently detects 10(1) organisms. MIPA detected 76% (38/50) of culture positive urines and in addition three urines that were culture negative were shown to be positive by this method of detection. Consequently we conclude that whilst MIPA is an improvement on previously published PCR detection methods, the culture of the organism is still the standard against which other detection methods have to be compared.

Detection of animal pathogens by using the polymerase chain reaction (PCR)

The polymerase chain reaction (PCR) is a nucleic acid-based technique that enables the rapid and sensitive detection of specific micro-organisms. Although this technique is widely used in veterinary research, it has not yet found applications in routine microbiological analysis of veterinary clinical samples. However, advances in sample preparation together with the increasing availability of specific gene sequences will probably lead to the more widespread diagnostic use of PCR in the future. PCR is likely to have a strong impact in the epidemiology, treatment and prevention of animal infectious diseases.