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Urinary tract infection (UTI) is one of the most common bacterial infections among humans. Urine culture is the gold standard diagnostic method for UTI; however, the dipstick test for nitrite is a widely used method signalling the presence of urinary nitrate-reducing bacteria. Unlike the gold standard, the dipstick test is easy to perform, while it is also less time-consuming and less expensive, and produces a result in a few minutes. This study investigates the sensitivity of the dipstick test for nitrite compared with the Griess test in urine samples from UTI caused by Enterobacterales species. We used the Griess test, which is the gold standard in nitrite measurement, to determine the sensitivity of the nitrite dipstick test. Semiquantitative urine culture was performed using standard procedures, and Enterobacterales identification was performed by manual conventional biochemical tests. In the first sample selection, 3 % (8/267) of urine samples suspected of UTI, analysed from March to April 2016, were nitrite-negative by dipstick test but positive for Enterobacterales in the urine culture. In the second sample selection, 5 % (2/44) of urine samples from October to December 2022 were also nitrite-negative but showed urine Enterobacterales isolation. All nitrite-negative dipstick results were consistent with the Griess test. Escherichia coli was the most prevalent bacterium, followed by Klebsiella pneumoniae, independent of sample selection. The dipstick test is a safe alternative for investigating nitrite in urine samples. We believe that the cause of nitrite-negative results is a lack of dietary nitrate, dilution of urine and exogenous interference (e.g. ascorbic acid). These findings support the idea that standard urine culture is necessary to rule out UTI.

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En el presente manual se describen las mutaciones detectadas mediante tiras reactivas en pruebas con sondas lineales (LPA) tanto de primera como de segunda línea, y se brinda información sobre su asociación con la farmacorresistencia fenotípica, con base en el catálogo de la OMS de mutaciones del complejo M. tuberculosis y su relación con la resistencia a los fármacos y las concentraciones inhibitorias mínimas (CIM) de los fármacos de primera y segunda línea informadas por la OMS. Asimismo, se describe la interpretación de las pruebas, las pruebas diagnósticas complementarias y las consecuencias clínicas de la presencia de mutaciones específicas y de la resistencia inferida. En la guía también se presentan estudios de casos con ejemplos de resultados de LPA y se describe la forma como se deben informar los resultados al personal médico, con modelos recomendados de informes adaptables

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Objetivou-se verificar a compatibilidade entre diferentes marcas de tiras reagentes para urinálise, tanto de uso veterinário, como de uso humano, e confrontar os parâmetros semiquantitativos desse instrumento com métodos quantitativos. Para isso, foram analisadas 77 amostras frescas de urina de cães e gatos e testados 04 modelos de tiras reagentes. Quanto à densidade urinária, houve correlação razoável entre os métodos quantitativo e semiquantitativo naquelas amostras com pH ácido, mas não naquelas com pH neutro ou alcalino. Quanto à concentração proteica, houve similaridade de 53,3% a 83,3% entre as marcas testadas e quando comparadas com a análise fotométrica houve uma correlação razoável (rs = 0,69752 a 0,75074). Em ponto de corte de 15mg/dL de proteína, a sensibilidade da tira reagente foi 82,5% e 100% para urina canina e felina, respectivamente. No tocante à hematúria, houve divergência razoável entre a sedimentoscopia e as diferentes marcas de tiras reativas. Quanto à piúria, há uma baixa sensibilidade das tiras em relação às amostras caninas com muitos resultados falso-negativos (33% a 75%), enquanto em amostras felinas a sensibilidade foi de 100%. Assim, independente da marca, as tiras reagentes devem servir apenas como teste rápido de triagem, sendo mais apropriado o uso de métodos quantitativos na avaliação clínica do paciente a partir da urinálise.

The aim was to verify the compatibility between different brands of urinary dipsticks, for both human and veterinary use, and to compare the semiquantitative parameters of this instrument with quantitative methods. For this, 77 fresh samples of urine from dogs and cats were analyzed e and 04 models of reagent strips were tested. Regarding urinary density, a reasonable correlation was observed between the quantitative and semiquantitative methods in those samples with acidic pH, which did not occur in those with neutral or alkaline pH. Regarding the protein concentration, there was similarity from 53.3% to 83.3% between the brands and in the comparative analysis between the control strip and the photometric analysis, there was a reasonable correlation (rs = 0.69752 to 0.75074). In cut-off point of 15mg/dL protein, the sensitivity of the reagent strip was 82.5% and 100% for canine and feline urine, respectively. Regarding hematuria, there was a reasonable divergence of results between sedimentation and tested dipsticks. As for pyuria, there is a low sensitivity of the strips in relation to canine samples with many false negative results (33% to 75%), while in feline samples the sensitivity was 100%. Thus, regardless of the brands, the reagent strips should serve only as a rapid screening test, while the use of quantitative methods in the clinical evaluation of the patient from urinalysis is more appropriate.

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OBJECTIVE: To characterize diagnostic findings, test-retest repeatability, and correlations among lacrimal tests in dogs of diverse cephalic conformations. ANIMAL STUDIED: Fifty healthy dogs (25 brachycephalic, 25 nonbrachycephalic). PROCEDURES: A series of diagnostics were performed in each dog, allowing for a 10-minute interval between tests and repeating each test 24 hours later under similar conditions: corneal tactile sensation (CTS), strip meniscometry test (SMT), phenol red thread test (PRTT), endodontic absorbent paper point tear test (EAPPTT), Schirmer tear test-1 without (STT-1) or with nasolacrimal stimulation (NL-STT1), and Schirmer tear test-2 (STT-2). RESULTS: Mean ± SD test values were lower in brachycephalic vs. nonbrachycephalic dogs (except for SMT; 7.4 ± 2.0 mm/5 seconds vs 7.3 ± 2.4 mm/5 seconds), with statistically significant differences noted for CTS (1.8 ± 0.5 cm vs 3.4 ± 0.8 cm), PRTT (37.2 ± 4.0 mm/15 seconds vs 41.1 ± 5.5 mm/15 seconds), STT-1 (20.1 ± 3.4 mm/min vs 23.3 ± 5.7 mm/min), STT-2 (13.0 ± 3.4 mm/min vs 16.9 ± 3.9 mm/min), and NL-STT1 (23.2 ± 3.6 mm/min vs 27.1 ± 5.4 mm/min), and nonsignificant differences for EAPPTT (16.6 ± 2.7 mm/15 seconds vs 17.5 ± 2.9 mm/15 seconds). Nasolacrimal stimulation increased STT-1 values by 18% on average. Correlations among tests were generally weak to moderate (r < .70) except for a strong correlation between STT-1 and NL-STT1 (r = .83, P < .001). Test reliability was good although test-retest repeatability was generally poor to moderate, as depicted by low intraclass correlation coefficients (ICC ≤ 0.75) and wide 95% limits of agreement, except for CTS (ICC = 0.91). CONCLUSIONS: Corneal sensitivity and aqueous tear secretion are lower in brachycephalic dogs. A comprehensive assessment of the ocular surface requires the combination of several diagnostic tests. The nasolacrimal reflex may provide a useful diagnostic and therapeutic tool in dogs.

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BACKGROUND AND AIMS: Results from a recent study among 750 heroin users in three Mexico's northern border cities revealed an increase in white powder availability (also known as China white) and preference for this product among heroin users, as well as a general perception of increased overdose cases among this population. Here, we questioned whether those findings reflect an increased presence of heroin laced with fentanyl, which is associated with greater risks of overdose but that, until now, has not been described in Mexico. DESIGN: We tested fentanyl using highly sensitive test strips in syringe plungers, metal cookers and drug wrappings associated with heroin use. SETTING: Three injection sites in Tijuana, Baja California, México. PARTICIPANTS: Eighty-nine heroin users who interchanged paraphernalia for new syringes. MEASUREMENTS: We tested 59 residues of 'pure' white powder. The rest were white powder with black tar (n = 5) or white powder with crystal meth (n = 9), black tar with crystal meth (n = 1), black tar only (n = 13) and crystal meth only (n = 2). FINDINGS: Users believed that they consumed either white powder heroin, white powder heroin with crystal meth, white powder with black tar heroin or black tar heroin only. Analyses revealed that 93% (n = 55) of the 'pure' white powder samples had fentanyl. All (n = 9) the white powder samples mixed with crystal meth and 40% (n = 2) of the white powder with black tar were also laced with fentanyl. CONCLUSIONS: In a sample of 89 heroin users in Mexico, most white powder heroin users were unknowingly exposed to fentanyl, with fentanyl detected in 93% of white powder samples.

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OBJECTIVE: to confirm the accuracy of the pH test in identifying the placement of the gastric tube in newborns. METHOD: double-blind, diagnostic test study conducted with 162 newborns admitted to a neonatal intensive care unit and an intermediate care unit. The subjects were submitted to enteral intubation, followed by pH test with reagent strip, which was analyzed by a nurse, and radiological examination, analyzed by radiologist. Blinding was kept among professionals regarding test results. Diagnostic accuracy analysis of the pH test in relation to the radiological exam was performed. RESULTS: the sample consisted of 56.17% boys, with average birth weight of 1,886.79g (SD 743,41), 32.92 (SD 2.99) weeks of gestational age and the mean pH was 3.36 (SD 1.27). Considering the cutoff point of pH≤5.5, the sensitivity was 96.25%, specificity 50%, positive predictive value 99.35% and negative predictive value 14.29%. CONCLUSION: The pH test performed with reagent strips is sensitive to identify the correct placement of the gastric tube, so it can be used as an adjuvant technique in the evaluation of the gastric tube placement. In interpreting the results, pH ≤5.5 points to correct placement and values > 5.5 require radiological confirmation.

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The experiments reported in this Research Communication aimed to determine if a domestic strip test to detect ethanol residues in breast milk (Milkscreen®) is comparable to a previously established official method for detecting ethanol residues in milk. The two methods are examined in terms of overall sensitivity, robustness against storage and acidity and selectivity against formaldehyde residues. Here, Milkscreen® provided advantages, with faster results (2 min), good sensitivity (≥0.017%), no false results due formaldehyde residues and equal robustness against storage, but with lower sensitivity in acid milk samples. In summary, strip tests for the rapid detection of ethanol residues in breast milk can be used for screening purposes by dairy manufacturers, combining it with the official method to make a final diagnosis.

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Introducción: La peritonitis bacteriana espontánea requiere un diagnóstico temprano para el inicio de antibioticoterapia. El estudio diagnóstico ideal es el citoquímico del líquido ascítico, el cual puede ser costoso, demorado y de disponibilidad limitada en centros primarios de atención en salud. Objetivo: Evaluar la utilidad y precisión diagnóstica de las tiras reactivas Multistix 10SG para el diagnóstico de peritonitis bacteriana espontánea en pacientes cirróticos con ascitis. Materiales y métodos: Estudio observacional descriptivo de prueba diagnóstica en pacientes cirróticos con ascitis. Se determinó el conteo de leucocitos del líquido ascítico por la escala colorimétrica de la tira reactiva Multistix 10SG y se comparó con el gold standard para el diagnóstico (polimorfonucleares ≥ 250 células/mm³). Resultados: De 174 pacientes con ascitis (51,7% mujeres, promedio de edad 59 años) 30 fueron diagnosticados con peritonitis bacteriana espontánea. Con un punto de corte grado ++, la tira reactiva tuvo sensibilidad 73,3%, especificidad 96,5%, valor predictivo positivo 81,4%, valor predictivo negativo 94,5%, razón de probabilidad positiva 21,2 y razón de probabilidad negativa 0,27. Conclusiones: Las tiras reactivas tienen adecuada especificidad y valor predictivo negativo, siendo una herramienta de bajo costo, uso sencillo, rápida interpretación y fácil acceso, para apoyar la decisión de no iniciar antibiótico en pacientes con ascitis y sospecha de peritonitis bacteriana espontánea. Por su baja sensibilidad no reemplazan al estudio citoquímico como prueba de elección para el diagnóstico definitivo, pero si es útil para optimizar el abordaje inicial de estos pacientes.

Introduction: Spontaneous bacterial peritonitis requires an early diagnosis to start antibiotic therapy. The ideal diagnostic study is the cytochemical of ascites fluid, which can be expensive, delayed and of limited availability in primary health care centers. Objective: Evaluate the usefulness and diagnostic accuracy of Multistix 10SG test strips for the diagnosis of spontaneous bacterial peritonitis in cirrhotic patients with ascites. Materials and methods: Observational descriptive study of diagnostic test in cirrhotic patients with ascites. The leukocyte count of ascites fluid was determined by the colorimetric scale of the Multistix 10SG test strip and compared with the gold standard for diagnosis (polymorphonuclear ≥ 250 cells / mm³). Results: Of 174 patients with ascites (51.7% women, average age 59 years) 30 were diagnosed with spontaneous bacterial peritonitis. With a grade ++ cut-off point, the test strip had sensitivity 73.3%, specificity 96.5%, positive predictive value 81.4%, negative predictive value 94.5%, positive likelihood ratio 21.2 and negative likelihood ratio of 0.27. Conclusions: The test strips have adequate specificity and negative predictive value, being a low cost tool, simple use, quick interpretation and easy access, to support the decision not to start an antibiotic in patients with ascites and suspected spontaneous bacterial peritonitis. Due to their low sensitivity they do not replace the cytochemical study as the test of choice for the definitive diagnosis, but it is useful for optimizing the initial approach of these patients.

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INTRODUCTION: Spontaneous bacterial peritonitis requires an early diagnosis to start antibiotic therapy. The ideal diagnostic study is the cytochemical of ascites fluid, which can be expensive, delayed and of limited availability in primary health care centers. OBJECTIVE: Evaluate the usefulness and diagnostic accuracy of Multistix 10SG test strips for the diagnosis of spontaneous bacterial peritonitis in cirrhotic patients with ascites. MATERIALS AND METHODS: Observational descriptive study of diagnostic test in cirrhotic patients with ascites. The leukocyte count of ascites fluid was determined by the colorimetric scale of the Multistix 10SG test strip and compared with the gold standard for diagnosis (polymorphonuclear ≥ 250 cells / mm³). RESULTS: Of 174 patients with ascites (51.7% women, average age 59 years) 30 were diagnosed with spontaneous bacterial peritonitis. With a grade ++ cut-off point, the test strip had sensitivity 73.3%, specificity 96.5%, positive predictive value 81.4%, negative predictive value 94.5%, positive likelihood ratio 21.2 and negative likelihood ratio of 0.27. CONCLUSIONS: The test strips have adequate specificity and negative predictive value, being a low cost tool, simple use, quick interpretation and easy access, to support the decision not to start an antibiotic in patients with ascites and suspected spontaneous bacterial peritonitis. Due to their low sensitivity they do not replace the cytochemical study as the test of choice for the definitive diagnosis, but it is useful for optimizing the initial approach of these patients.

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BACKGROUND: The fluorescein clearance test (FCT) provides insight into the tear film dynamics. The purpose of this study was to describe an inexpensive and practical method for assessing FCT in dogs, using photography and software analysis, and to assess the retention time of 1 vs. 2 eye drops on the canine ocular surface. METHODS: (i) In vivo - Eight healthy German Shepherd dogs were recruited. Following topical anesthesia with 0.5% proxymetacaine, each eye sequentially received (1 week apart) either 1 drop (35 µL) or 2 drops (70 µL) of 0.5% fluorescein. A Schirmer strip was inserted in the ventral conjunctival fornix for 10 s at the following times: each 10 min for 100 min, 24 h, 48 h and 72 h. (ii) In vitro - Schirmer strips were placed for 10 s in contact with microplate wells containing 1 or 2 drops of 0.5% fluorescein. In both experiments, the fluorescein-impregnated Schirmer strips were immediately imaged, and the area and intensity of fluorescein uptake were analyzed with ImageJ software. For the in vitro experiment, images were evaluated by the same examiner (repeatability) or two examiners (reproducibility). RESULTS: Photography-based FCT was easy to perform and showed high repeatability and reproducibility (coefficients of variation ≤2.75%). In vivo, the area and intensity of fluorescein uptake on Schirmer strips were significantly greater at 30 min and 40 min post- fluorescein instillation in the 2 drops vs. 1 drop groups (p ≤ 0.044). Compared to baseline, the residual fluorescein uptake on Schirmer strips was < 5% at 60 min and 90 min in the 1 drop and 2 drops groups, respectively. CONCLUSIONS: Photography-based FCT is a practical and reliable diagnostic tool with various clinical and research applications in veterinary medicine. Instillation of two drops provided greater amount and longer retention on the anesthetized canine ocular surface than a single drop. Fluorescein clearance time of a single drop in dolichocephalic dogs is 60 min.

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