EVALUACIÓN DE LA SENSIBILIDAD Y ESPECIFICIDAD DE DOS MÉTODOS DE BACILOSCOPIA

La baciloscopia es la herramienta más útil en el diagnóstico, control y tratamiento de latuberculosis, sobre todo en países en desarrollo. El propósito fue demostrar si existíadiferencia en la sensibilidad y especificidad en la baciloscopia de área extensa (BACEX)con respecto a la de área reducida (BACRED). Fue un estudio de corte transversal, noprobabilístico, realizado en esputo de 100 pacientes que acudieron al HospitalUniversitario "Doctor José Eleuterio González" UANL en la cd. de Monterrey, el esputodebería tener calidad, aspecto purulento, contenido en un recipiente plástico de altadensidad, translúcido y estéril, se estandarizó el área de observación, la cantidad demuestra y experiencia de los observadores. El 58% fueron del género masculino, 42%femenino; promedio de edad fue de 49 años (rango 11 a 103), 76% tuvo el cultivonegativo, 23% positivo para Mycobacterium tuberculosis, 1% para Mycobacteriumchelonae. La BACEX observada por microscopistas inexpertos tuvo una sensibilidad del45% (IC95 0.25, 0.65) y especificidad del 93% (IC950.88, 0.98), para la BCRED lasensibilidad fue del 54% (IC95 0.43, 0.65) y especificidad del 93% (IC95 0.88, 0.98); LaBACEX y la BACRED observada por el microscopista medianamente experto, lasensibilidad fue del 75% (IC95 0.58, 0.92) y especificidad del 98% (IC95 0.95, 1.00);para el experto, la sensibilidad fue del 79% (IC95 0.63, 0.95) y especificidad del 100%.No se encontró diferencia significativa entre la sensibilidad y especificidad de ambosmétodos, la experiencia fue un factor determinante que influyó en el valor diagnósticode la baciloscopia, todo laboratorio que realice baciloscopias deberá establecercontroles de calidad interno y externo, los microscopistas inexpertos deberán recibirentrenamiento.AbstractThe direct microscopic exam is the most useful tool in the diagnosis, control andtreatment of the tuberculosis, mainly in countries in development. The purpose was todemonstrate if difference existed in the sensibility and specificity in the directmicroscopic exam of extensive area (BACEX) with regard to that of reduced area(BACRED). it was a study carried out in 100 patients' that went to the HospitalUniversity Doctor José Jose Eleuterio González UANL (Monterrey, N.L, México). Thesputum should have quality and aspect, content in a plastic recipient of high density,translucent and sterile, it was standardized the observation area, the quantity ofsample and the observers' experience. 58% was of the masculine and , feminine42 %;age average was of 49 years (range 11 at 103), 76% had the negative cultivation,positive23 % for Mycobacterium tuberculosis, 1% for Mycobacterium chelonae. TheBACEX observed by inexpert personal had a sensibility of 45% (IC95 0.25, 0.65) andspecificity of 93% (IC95 0.88, 0.98), for the BCRED the sensibility was of 54% (IC950.43, 0.65) and specificity of 93% (IC95 0.88, 0.98); The BACEX and the BACREDobserved by the fairly expert personal, the sensibility was of 75% (IC95 0.58, 0.92)and specificity of 98% (IC95 0.95, 1.00); for the expert, the sensibility it was of 79%(IC95 0.63, 0.95) and specificity of 100%. he/she was not significant differencebetween the sensibility and specificity of both methods, the experience was a decisivefactor that influenced in the value diagnosis of the direct microscopic exam ,alllaboratory that it carries out direct microscopic exam it will establish quality intern'scontrols and external, the inexpert personal will receive training. Palabras clave: Tuberculosis, baciloscopia, cultivo, Tuberculosis, direct microscopic exam, cultiv

Probability of a successful platelet dose according to the number of platelet concentrates

Introduction: Platelet transfusion for prophylactic or therapeutic purposes is a common practice. The outcome evaluated in using platelets for prophylactic purposes has been preventing clinically significant bleeding. Transfusion guidelines recommend using platelet transfusion for prophylactic purposes based on the clinical scenario and a peripheral blood platelet threshold. Methods: A retrospective study was carried out, with the platelet count of the registry of quality control of platelet concentrates (PC), obtaining a total of 100. Age, sex, blood group, and peripheral blood platelets were compared with donors not included in quality control. The sum of the platelet count of all possible combinations of the 100 PCs was obtained for the 2-3 PCs scenarios and the 4-8 PCs scenarios, a simulation of 1,000,000 iterations with random sampling without replacement and the sum of the platelet count of the combinations obtained was performed. The proportion of successful doses in the distribution was obtained according to the number of PCs. Results: No statistically significant difference was found between donors included in quality control and those not included. The probability of administering a dose of ≥ 1.5 × 10^11 platelets is 97.33% and 99.99% for 3-4 PCs, respectively. Conclusions: This study may be useful for the physician who indicates PC for prophylactic purposes, using an appropriate number of PCs, and optimizing the available inventory

Estudio comparativo entre una prueba rápida y RT-PCR tiempo real en el diagnóstico de influenza AH1N1 2009

RESUMEN Objetivo. Comparar la prueba QuickVue Influenza A+B empleando como estándar la RT-PCR tiempo real para influenza AH1N1 2009. Material y métodos. Estudio retrospectivo-comparativo de 135 muestras de vías respiratorias de individuos sintomáticos para influenza procesadas de mayo 2009 a octubre 2010. Las pruebas citadas se realizaron simultáneamente. Se utilizó el software Confidence Interval Analysis 2000. Resultados. Sensibilidad 62.96; especificidad 94.44; valor predictivo negativo 62.9; valor predictivo positivo 94.44; razón de probabilidad positiva 11.33 y razón de probabilidad negativa 0.39. Se calcularon intervalos de confianza a 95. Discusión. Los valores obtenidos concuerdan con otros estudios donde la sensibilidad fluctúa de 50 a 70 y especificidad entre 90 y 95 por ciento. La prueba QuickVue Influenza A+B es rápida, simple y de menor costo que el RT-PCR tiempo real, útil para identificar el tipo de virus en brotes de influenza de una población determinada ABSTRACT Objective. Compare QuickVue Influenza A+B test with real-time RT-PCR for the diagnosis of influenza AH1N1 2009. Material and Methods. Retrospective-comparative study of 135 respiratory specimens from individuals with symptoms of influenza processed from May 2009 to October 2010. The above mentioned tests were performed simultaneously. For statistic analysis the software of Confidence Interval Analysis 2000 was used. Results. The parameters obtained were: sensitivity 62.96; specificity 94.44; negative predictive value 62.9; positive predictive value 94.44; positive likelihood ratio 11.33; negative likelihood ratio 0.39. Confidence intervals to 95, were calculated to all of the above data. Discussion. The test QuickVue Influenza A+B is a rapid, simple test, with lower cost than real-time RT-PCR useful for identifying the type of virus outbreaks of influenza in a given population. It correlates well with more specific test and similar reports

Microbiological and Molecular Characterization of Staphylococcus hominis Isolates from Blood

Background: Among Coagulase-Negative Staphylococci (CoNS), Staphylococcus hominis represents the third most common organism recoverable from the blood of immunocompromised patients. The aim of this study was to characterize biofilm formation, antibiotic resistance, define the SCCmec (Staphylococcal Chromosomal Cassette mec) type, and genetic relatedness of clinical S. hominis isolates. Methodology: S. hominis blood isolates (n = 21) were screened for biofilm formation using crystal violet staining. Methicillin resistance was evaluated using the cefoxitin disk test and the mecA gene was detected by PCR. Antibiotic resistance was determined by the broth microdilution method. Genetic relatedness was determined by pulsed-field gel electrophoresis (PFGE) and SCCmec typed by multiplex PCR using two different methodologies described for Staphylococcus aureus. Results: Of the S. hominis isolates screened, 47.6% (10/21) were categorized as strong biofilm producers and 23.8% (5/21) as weak producers. Furthermore, 81% (17/21) of the isolates were methicillin resistant and mecA gene carriers. Resistance to ampicillin, erythromycin, and trimethoprim was observed in .70% of isolates screened. Each isolate showed a different PFGE macrorestriction pattern with similarity ranging between 0–95%. Among mecA-positive isolates, 14 (82%) harbored a non-typeable SCCmec type: eight isolates were not positive for any ccr complex; four contained the mec complex A ccrAB1 and ccrC, one isolate contained mec complex A, ccrAB4 and ccrC, and one isolate contained the mec complex A, ccrAB1, ccrAB4, and ccrC. Two isolates harbored the association: mec complex A and ccrAB1. Only one strain was typeable as SCCmec III. Conclusions: The S. hominis isolates analyzed were variable biofilm producers had a high prevalence of methicillin resistance and resistance to other antibiotics, and high genetic diversity. The results of this study strongly suggested that S. hominis isolates harbor new SCCmec structural elements and might be reservoirs of ccrC1 in addition to ccrAB1 and mec complex A

Urinalysis: diagnostic performance of urine dipstick compared to an automated microscopic method

Introduction: Urinalysis is one of the most important clinical laboratory tests because numerous pathologies can manifest or be suspected through this test. Although the previous reports mention that urinary microscopy is a fundamental part of urinalysis for diagnostic support of various conditions, there is a debate about the utility of this test section in a certain patient population. The aim of this study was to determine the diagnostic performance of the urinary dipstick analysis and the potential risks of false-negative (FN) results. Material and methods: This is a retrospective and observational study, and urinalysis information was obtained from non-hospitalized patients. The dipstick and microscopic analyses were performed using the Clinitek-ATLAS (index test) and iQ200-SPRINT (reference standard) devices. Dipstick or microscopy analyses were positive if ≥ 1 parameters were abnormal. A Bayesian hierarchal beta-binomial model was carried out for each performance parameter. Risk analysis was performed as proposed in the literature. Results: Five hundred and fifty-two patients were included in the study. The posterior median at group level was 94% (credible interval 95% [CrI 95%] 89.9-97%) for sensitivity (Se), 57.1% (CrI 95%, 50.1-64.1%) for specificity, and 5.8% (CrI 95%, 2.59-9.64%) for FN rate (FNR). The posterior probability Se > 90% was 95.9% at a group level. The risk analysis found only low-risk false-negative events. Conclusions: The performance of the dipstick analysis was appropriate, with a good certainty of Se > 90% and a FNR < 10% at the operator level. Omission of microscopic analysis can be a safe action in a patient with a negative dipstick since FNs with a clinical impact are not expected

Antibiotic Susceptibility of Biofilm Cells and Molecular Characterisation of Staphylococcus hominis Isolates from Blood

Objectives We aimed to characterise the staphylococcal cassette chromosome mec (SCCmec) type, genetic relatedness, biofilm formation and composition, icaADBC genes detection, icaD expression, and antibiotic susceptibility of planktonic and biofilm cells of Staphylococcus hominis isolates from blood. Methods The study included 67 S. hominis blood isolates. Methicillin resistance was evaluated with the cefoxitin disk test. mecA gene and SCCmec were detected by multiplex PCR. Genetic relatedness was determined by pulsed-field gel electrophoresis. Biofilm formation and composition were evaluated by staining with crystal violet and by detachment assay, respectively; and the biofilm index (BI) was determined. Detection and expression of icaADB Cgenes were performed by multiplex PCR and real-time PCR, respectively. Antibiotic susceptibilities of planktonic cells (minimum inhibitory concentration, MIC) and biofilm cells (minimum biofilm eradication concentration, MBEC) were determined by the broth dilution method. Results Eighty-five percent (57/67) of isolates were methicillin resistant and mecA positive. Of the mecA-positive isolates, 66.7% (38/57) carried a new putative SCCmec type. Four clones were detected, with two to five isolates each. Among all isolates, 91% (61/67) were categorised as strong biofilm producers. Biofilm biomass composition was heterogeneous (polysaccharides, proteins and DNA). All isolates presented the icaD gene, and 6.66% (1/15) isolates expressed icaD. This isolate presented the five genes of ica operon. Higher BI and MBEC values than the MIC values were observed for amikacin, vancomycin, linezolid, oxacillin, ciprofloxacin, and chloramphenicol. Conclusions S. hominis isolates were highly resistant to methicillin and other antimicrobials. Most of the detected SCCmec types were different than those described for S. aureus. Isolates indicated low clonality. The results indicate that S. hominis is a strong biofilm producer with an extracellular matrix with similar composition of proteins, DNA and N-acetylglucosamine; and presents high frequency and low expression of icaD gene. Biofilm production is associated with increased antibiotic resistance

Molecular epidemiology of coagulase-negative bloodstream isolates: detection of Staphylococcus epidermidis ST2, ST7 and linezolid-resistant ST23

The mechanisms contributing to persistence of coagulase-negative staphylococci are diverse; to better understanding of their dynamics, the characterization of nosocomial isolates is needed. Our aim was to characterize phenotypic and molecular characteristics of Staphylococcus epidermidis and Staphylococcus haemolyticus human blood isolates from two tertiary care hospitals in Mexico, the Hospital Universitario in Monterrey and the Hospital Civil in Guadalajara. Antimicrobial susceptibility was determined. Biofilm formation was assessed by crystal violet staining. Detection of the ica operon and Staphylococcal Cassette Chromosome mec typing were performed by PCR. Clonal relatedness was determined by Pulsed-fiel gel electrophoresis and Multi locus sequence typing. Methicillin-resistance was 85.5% and 93.2% for S. epidermidis and S. haemolyticus, respectively. Both species showed resistance >70% to norfloxacin, clindamycin, levofloxacin, trimethoprim/sulfamethoxazole, and erythromycin. Three S. epidermidis and two S. haemolyticus isolates were linezolid-resistant (one isolate of each species was cfr+). Most isolates of both species were strong biofilm producers (92.8% of S. epidermidis and 72.9% of S. haemolyticus). The ica operon was amplified in 36 (43.4%) S. epidermidis isolates. SCCmec type IV was found in 47.2% of the S. epidermidis isolates and SCCmec type V in 14.5% of S. haemolyticus isolates. No clonal relatedness was found in either species. Resistance to clindamycin, levofloxacin, erythromycin, oxacillin, and cefoxitin was associated with biofilm production for both species (p < 0.05). A G2576T mutation in 23S rRNA gene was detected in an S. haemolyticus linezolid-resistant isolate. All linezolid-resistant S. epidermidis isolates belonged to ST23; isolate with SCCmec type IV belonged to ST7, and isolate with SCCmec type III belonged to ST2. This is the first report of ST7 in Mexico. There was a high genetic diversity in both species, though both species shared characteristics that may contibute to virulence

Sexually transmitted pathogens, coinfections and risk factors in patients attending obstetrics and gynecology clinics in Jalisco, Mexico

Objetivo. Determinar la frecuencia de nueve patógenos de transmisión sexual, coinfecciones y factores de riesgo en pacientes que acudieron a una consulta de ginecología y obstetricia en Jalisco, México. Material y métodos. Se analizaron muestras de 662 pacientes que asistieron a la consulta de ginecología y obstetricia. Se detectaron Treponema pallidum, VIH y VHC mediante serología. Se detectó VPH por Reacción de Cadena de Polimerasa (PCR) y sus genotipos se detectaron por Polimorfismos de Longitud de Fragmentos de Restricción (RFLP). Se detectaron Trichomonas vaginalis, VHS-1, VHS-2, Mycoplasma genitalium, Neisseria gonorrhoeae y T. pallidum por PCR múltiple. Resultados. Por serología, la frecuencia de VIH fue 6.8%, de T. pallidum fue 2.26% y de VHC fue 0.15%. Por PCR, la frecuencia más alta fue de VPH (13.9%, el genotipo más frecuente fue el 16, 33.7%), seguida de T. vaginalis (14.2%), VHS-1 (8.5%), M. genitalium (2.41%), N. gonorrhoeae (2.11%), VHS-2 (1.8%) y T. pallidum (1.05%). Los pacientes infectados con T. vaginalis presentaron más probabilidades de tener múltiples coinfecciones (p = 0.01). Conclusiones. La frecuencia de infección por VPH, VHS-1, VHS-2, M. genitalium y T. vaginalis fue menor a lo reportado. Sin embargo, se detectó una alta frecuencia de VIH, T. pallidum, y N. gonorrhoeae. ABSTRACT Objective. To determine the frequency of nine sexually transmitted pathogens, coinfections and risk factors in patients attending obstetrics and gynecology clinics in Jalisco, Mexico. Materials and methods. Samples from 662 patients attending obstetrics and gynecology clinics were analyzed. Treponema pallidum, HIV, and HCV were detected by serology. HPV was detected by Polimerase Chain Reac- tion (PCR), and its genotype was determined by Restriction Fragment Length Polymorphism (RFLP). Trichomonas vaginalis, HSV-1, HSV-2, Mycoplasma genitalium, Neisseria gonorrhoeae and T. pallidum were detected by multiplex PCR. Results. By serology, HIV frequency was 6.8%, T. pallidum was 2.26%, and HCV was 0.15%. By PCR, HPV frequency was 13.9%, (more frequent genotype was 16, 33.7%), followed by T. vaginalis (14.2%), HSV-1 (8.5%), M. genitalium (2,41%), N. gonorrhoeae (2.11%), HSV-2 (1.8%), and T. pallidum (1.05%). Patients infected with T. vaginalis were more likely to have multiple coinfections (p = 0.01). Conclusion. The frequency of HPV, HVS-1, HSV-2, M. genitalium and T. vaginalis was lower than that reported. However, a high frequency of HIV, T. pallidum, and N. gonorrhoeae was detected

Evaluación de la sensibilidad y especificidad de dos métodos de baciloscopia

A pesar que la tuberculosis es una enfermedad que se puede prevenir y curar, continúa siendo un problema serio de salud pública para el mundo y que causa millones de casos nuevos cada año. Actualmente una tercera parte de la población se encuentra infectada por el bacilo de la tuberculosis, cada año hay 8 millones de casos nuevos, la Tuberculosis, mata cada año a dos millones de personas, entre el 2000 y el 2020 se infectarán mil millones de personas y 35 millones morirán(1) en 1998 la tasa media por 100,000 habs. De tuberculosis pulmonar en México fue de 18.74, el rango fluctuó de 3.65 en Zacatecas hasta 47.47 para Chiapas, la tasa en el estado de Nuevo León fue de 31.10, el rango de la tasa de mortalidad para el país fue de 1.42 para el estado de México hasta 8.60 para Chiapas, en Nuevo León fue de 5.0 (2