AID TB resistance line probe assay for rapid detection of resistant Mycobacterium tuberculosis in clinical samples

OBJECTIVES

To determine the sensitivity and specificity of AID TB Resistance line probe assay (AID Diagnostika, Germany) to detect Mycobacterium tuberculosis and its resistance to first- and second-line drugs in clinical samples using BACTEC 460TB as the reference standard.

METHODS

The test consists on three strips to detect resistance to isoniazid/rifampicin, fluoroquinolones/ethambutol, and kanamycin/amikacin/capreomycin/streptomycin, respectively. This test was performed on 65 retrospectively selected clinical samples corresponding to 32 patients.

RESULTS

A valid result was obtained for 92.3% (60/65), 90.8% (59/65) and 78.5% (51/65) of the samples tested, considering the three strips, respectively. Global concordance rates between AID and BACTEC for detecting resistance to isoniazid, rifampicin, fluoroquinolones, ethambutol, kanamycin/capreomycin and streptomycin were 98.3% (59/60), 100% (60/60), 91.5% (54/59), 72.9% (43/59), 100% (51/51) and 98.0% (50/51), respectively. Regarding the discordant results obtained between AID and BACTEC, the alternative molecular methods performed (GenoType MTBDRplus, GenoType MTBDRsl [Hain Lifescience, Germany] and/or pyrosequencing) confirmed the genotypic result in 90.9% (20/22) of the cases.

CONCLUSIONS

AID line probe assay is a useful tool for the rapid detection of drug resistance in clinical samples enabling an initial therapeutic approach. Nevertheless, for a correct management of drug resistant tuberculosis patients, molecular results should be confirmed by a phenotypic method.

Loop versus end colostomy reversal: has anything changed?

PURPOSE

Though primary repair of colon injuries is preferred, certain injury patterns require colostomy creation. Colostomy reversal is associated with significant morbidity and healthcare cost. Complication rates may be influenced by technique of diversion (loop vs. end colostomy), though this remains ill-defined. We hypothesized that reversal of loop colostomies is associated with fewer complications than end colostomies.

METHODS

This is a retrospective, multi-institutional study (four, level-1 trauma centers) of patients undergoing colostomy takedown for trauma during the time period 1/2006-12/2012. Data were collected from index trauma admission and subsequent admission for reversal and included demographics and complications of reversal. Student's t test was used to compare continuous variables against loop versus end colostomy. Discrete variables were compared against both groups using Chi-squared tests.

RESULTS

Over the 6-year study period, 218 patients underwent colostomy takedown after trauma with a mean age of 30; 190 (87%) were male, 162 (74%) had penetrating injury as their indication for colostomy, and 98 (45%) experienced at least one complication. Patients in the end colostomy group (n = 160) were more likely to require midline laparotomy (145 vs. 18, p < 0.001), had greater intra-operative blood loss (260.7 vs. 99.4 mL, p < 0.001), had greater hospital length of stay (8.4 vs. 5.5 days, p < 0.001), and had more overall complications (81 vs. 17, p = 0.005) than patients managed with loop colostomy (n = 58).

CONCLUSIONS

Local takedown of a loop colostomy is safe and leads to shorter hospital stays, less intra-operative blood loss, and fewer complications when compared to end colostomy.

Meningococcal carriage prevalence in university students, 1824 years of age in Santiago, Chile

INTRODUCTION

Neisseria meningitidis invasive disease is a major public health problem. Pharyngeal carriage is considered a prerequisite for invasive infection. Prevalence reaches 10% in general population and up to 30% in the 20-24 years age group. The aim of this study was to asses pharyngeal carriage prevalence in healthy subjects aged 18-24 years, and as secondary endpoints evaluate known risk factors, to identify serogroups and sequence in the isolated strains.

METHODS

Cross-sectional study in 500 healthy subjects; students from Universidad de Chile aged 18-24 years, Santiago, Chile, October 2012. Each subject underwent a risk factor survey prior to throat culture sampling. Samples were processed in one central Microbiology Laboratory of Hospital Luis Calvo Mackenna and serogrouping and sequencing was performed at Instituto de Salud Pública de Chile.

RESULTS

We obtained throat samples from 500 healthy subjects, 20 (4%) positive for N. meningitidis. Of positive strains 20% were serogroup B, 15% W and the rest non groupable. The median age was 20 years, 50% were men. Of the risk factors evaluated, 24% were current smokers, 16% shared a room, 72% had kissed someone during the last month, 64% had gone to pub and 76% had consumed alcohol in the same period of time.

DISCUSSION

Literatures meningococcal carriage prevalence reaches up to 30% in people aged 18-24 years. Prevalence in our study was 4%. Different interpretations could be given; one could be the absence of overcrowding in our students because of the lack of dorms in our scholar system and also the characteristics of our enrolled group.

CONCLUSIONS

Our results suggest the necessity to extend the study to other age groups and to other cities, to better understand the Chilean reality, as well as others regions of America, considering that these results cannot be extrapolated to another countries.

To achieve an earlier IFN-γ response is not sufficient to control Mycobacterium tuberculosis infection in mice

The temporo-spatial relationship between the three organs (lung, spleen and lymph node) involved during the initial stages of Mycobacterium tuberculosis infection has been poorly studied. As such, we performed an experimental study to evaluate the bacillary load in each organ after aerosol or intravenous infection and developed a mathematical approach using the data obtained in order to extract conclusions. The results showed that higher bacillary doses result in an earlier IFN-γ response, that a certain bacillary load (BL) needs to be reached to trigger the IFN-γ response, and that control of the BL is not immediate after onset of the IFN-γ response, which might be a consequence of the spatial dimension. This study may have an important impact when it comes to designing new vaccine candidates as it suggests that triggering an earlier IFN-γ response might not guarantee good infection control, and therefore that additional properties should be considered for these candidates.

GaInN/GaN Multi-Quantum Well Laser Diodes Grown by Low-Pressure Metalorganic Chemical Vapor Deposition

We report the growth, fabrication and characterization of GaInN/GaN multi-quantum well lasers grown on (00·1) sapphire substrates by low pressure metalorganic chemical vapor deposition. The threshold current density of a 1800 μm long cavity length laser was 1.4 kA/cm2 with a threshold voltage of 25 V. These lasers exhibited series resistances of 13 and 14 Ω at 300 and 79 K, respectively.

Cost-effectiveness analysis of the bivalent and quadrivalent human papillomavirus vaccines from a societal perspective in Colombia

Objective

To compare costs and effectiveness of three strategies used against cervical cancer (CC) and genital warts: (i) Screening for CC; (ii) Bivalent Human Papillomavirus (HPV) 16/18 vaccine added to screening; (iii) Quadrivalent HPV 6/11/16/18 vaccine added to screening.

Methods

A Markov model was designed in order to simulate the natural history of the disease from 12 years of age (vaccination) until death. Transition probabilities were selected or adjusted to match the HPV infection profile in Colombia. A systematic review was undertaken in order to derive efficacy values for the two vaccines as well as for the operational characteristics of the cytology test. The societal perspective was used. Effectiveness was measured in number of averted Disability Adjusted Life Years (DALYS).

Results

At commercial prices reported for 2010 the two vaccines were shown to be non-cost-effective alternatives when compared with the existing screening strategy. Sensitivity analyses showed that results are affected by the cost of vaccines and their efficacy values, making it difficult to determine with certainty which of the two vaccines has the best cost-effectiveness profile. To be ‘cost-effective’ vaccines should cost between 141 and 147 USD (Unite States Dollars) per vaccinated girl at the most. But at lower prices such as those recommended by WHO or the price of other vaccines in Colombia, HPV vaccination could be considered very cost-effective.

Conclusions

HPV vaccination could be a convenient alternative for the prevention of CC in Colombia. However, the price of the vaccine should be lower for this vaccination strategy to be cost-effective. It is also important to take into consideration the willingness to pay, budgetary impact, and program implications, in order to determine the relevance of a vaccination program in this country, as well as which vaccine should be selected for use in the program.

Damaging role of neutrophilic infiltration in a mouse model of progressive tuberculosis

Tuberculosis was studied using an experimental model based on the C3HeB/FeJ mouse strain, which mimics the liquefaction of caseous necrosis occurring during active disease in immunocompetent adults. Mice were intravenously infected with 2 × 10(4) Colony Forming Units of Mycobacterium tuberculosis and their histopathology, immune response, bacillary load, and survival were evaluated. The effects of the administration of drugs with anti-inflammatory activity were examined, and the C3H/HeN mouse strain was also included for comparative purposes. Massive intra-alveolar neutrophilic infiltration led to rapid granuloma growth and coalescence of lesions into superlesions. A central necrotic area appeared showing progressive cellular destruction, the alveoli cell walls being initially conserved (caseous necrosis) but finally destroyed (liquefactive necrosis). Increasing levels of pro-inflammatory mediators were detected in lungs. C3HeB/FeJ treated with anti-inflammatory drugs and C3H/HeN animals presented lower levels of pro-inflammatory mediators such as TNF-α, IL-17, IL-6 and CXCL5, a lower bacillary load, better histopathology, and increased survival compared with untreated C3HeB/FeJ. The observation of massive neutrophilic infiltration suggests that inflammation may be a key factor in progression towards active tuberculosis. On the basis of our findings, we consider that the C3HeB/FeJ mouse model would be useful for evaluating new therapeutic strategies against human tuberculosis.

E-cadherin determines Caveolin-1 tumor suppression or metastasis enhancing function in melanoma cells

The role of caveolin-1 (CAV1) in cancer is highly controversial. CAV1 suppresses genes that favor tumor development, yet also promotes focal adhesion turnover and migration of metastatic cells. How these contrasting observations relate to CAV1 function in vivo is unclear. Our previous studies implicate E-cadherin in CAV1-dependent tumor suppression. Here, we use murine melanoma B16F10 cells, with low levels of endogenous CAV1 and E-cadherin, to unravel how CAV1 affects tumor growth and metastasis and to assess how co-expression of E-cadherin modulates CAV1 function in vivo in C57BL/6 mice. We find that overexpression of CAV1 in B16F10 (cav-1) cells reduces subcutaneous tumor formation, but enhances metastasis relative to control cells. Furthermore, E-cadherin expression in B16F10 (E-cad) cells reduces subcutaneous tumor formation and lung metastasis when intravenously injected. Importantly, co-expression of CAV1 and E-cadherin in B16F10 (cav-1/E-cad) cells abolishes tumor formation, lung metastasis, increased Rac-1 activity, and cell migration observed with B16F10 (cav-1) cells. Finally, consistent with the notion that CAV1 participates in switching human melanomas to a more malignant phenotype, elevated levels of CAV1 expression correlated with enhanced migration and Rac-1 activation in these cells.

Ibuprofen therapy resulted in significantly decreased tissue bacillary loads and increased survival in a new murine experimental model of active tuberculosis

C3HeB/FeJ mice infected with Mycobacterium tuberculosis were used in an experimental animal model mimicking active tuberculosis in humans to evaluate the effect of antiinflammatory agents. No other treatment but ibuprofen was given, and it was administered when the animals' health started to deteriorate. Animals treated with ibuprofen had statistically significant decreases in the size and number of lung lesions, decreases in the bacillary load, and improvements in survival, compared with findings for untreated animals. Because antiinflammatory agents are already on the market, further clinical trials should be done to evaluate this effect in humans as soon as possible, to determine their suitability as coadjuvant tuberculosis treatment.

Progesterone promotes focal adhesion formation and migration in breast cancer cells through induction of protease-activated receptor-1

Progesterone and progestins have been demonstrated to enhance breast cancer cell migration, although the mechanisms are still not fully understood. The protease-activated receptors (PARs) are a family of membrane receptors that are activated by serine proteases in the blood coagulation cascade. PAR1 (F2R) has been reported to be involved in cancer cell migration and overexpressed in breast cancer. We herein demonstrate that PAR1 mRNA and protein are upregulated by progesterone treatment of the breast cancer cell lines ZR-75 and T47D. This regulation is dependent on the progesterone receptor (PR) but does not require PR phosphorylation at serine 294 or the PR proline-rich region mPRO. The increase in PAR1 mRNA was transient, being present at 3  h and returning to basal levels at 18  h. The addition of a PAR1-activating peptide (aPAR1) to cells treated with progesterone resulted in an increase in focal adhesion (FA) formation as measured by the cellular levels of phosphorylated FA kinase. The combined but not individual treatment of progesterone and aPAR1 also markedly increased stress fiber formation and the migratory capacity of breast cancer cells. In agreement with in vitro findings, data mining from the Oncomine platform revealed that PAR1 expression was significantly upregulated in PR-positive breast tumors. Our observation that PAR1 expression and signal transduction are modulated by progesterone provides new insight into how the progestin component in hormone therapies increases the risk of breast cancer in postmenopausal women.

Dengue virus identification by transmission electron microscopy and molecular methods in fatal dengue hemorrhagic fever

Dengue virus is the most significant virus transmitted by arthropods worldwide and may cause a potentially fatal systemic disease named dengue hemorrhagic fever. In this work, dengue virus serotype 4 was detected in the tissues of one fatal dengue hemorrhagic fever case using electron immunomicroscopy and molecular methods. This is the first report of dengue virus polypeptides findings by electron immunomicroscopy in human samples. In addition, not-previously-documented virus-like particles visualized in spleen, hepatic, brain, and pulmonary tissues from a dengue case are discussed.

Clinical validation of the European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE) II criteria in an open-access unit: a prospective study

BACKGROUND AND STUDY AIMS

The European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE I) criteria were recently updated (EPAGE II), but no prospective studies have used these criteria in clinical practice. The aim of the current study was to validate the EPAGE II criteria in an open-access endoscopy unit.

PATIENTS AND METHODS

A prospective observational study was conducted in an open-access endoscopy unit at a tertiary care referral center. Consecutive outpatients (n = 1004; mean age 58.9 ± 13.1 years; 45 % men) were referred for diagnostic colonoscopy between September 2009 and February 2010. The appropriateness of colonoscopy was assessed based on EPAGE II criteria, and the relationship between appropriateness and both referral doctor and detection of significant lesions was examined. The effectiveness of EPAGE II criteria in assessing appropriateness was measured by means of sensitivity, specificity, and positive and negative predictive values for detecting significant lesions.

RESULTS

Colonoscopic cecal intubation was achieved in 956 patients (95.2 %). Most referral doctors were gastroenterologists (58.0 %) and the most common indication was colorectal cancer (CRC) screening (35.2 %). EPAGE II criteria were applicable in 968 patients (96.4 %); of these patients, the indication was appropriate in 778 (80.4 %), inappropriate in 102 (10.5 %), and uncertain in 88 (9.1 %). Patients with appropriate or uncertain indications based on EPAGE II criteria had more relevant endoscopic findings than those with inappropriate indications (38.8 % vs. 24.5 %; OR 1.95, 95 %CI 1.22 - 3.13; P < 0.005). Sensitivity and negative predictive value of EPAGE II criteria for detecting significant lesions were 93.1 % (95 %CI 90 % - 96 %) and 75.5 % (95 %CI 67 % - 84 %), respectively, whereas for advanced neoplastic lesions these values were 98.0 % (95 %CI 95 % - 100 %) and 98.0 % (95 % CI 95 % - 100 %), respectively. Adherence to EPAGE II recommendations was an independent predictor of finding a significant lesion (OR 1.93, 95 %CI 1.20 - 3.11; P = 0.007).

CONCLUSIONS

EPAGE II is a simple, valid score for detecting inappropriate colonoscopies in clinical practice.

Donor-derived organ transplant transmission of coccidioidomycosis

Coccidioidomycosis in solid organ transplant recipients most often occurs as a result of primary infection or reactivation of latent infection. Herein, we report a series of cases of transplant-related transmission of coccidioidomycosis from a single donor from a non-endemic region whose organs were transplanted to 5 different recipients. In all, 3 of the 5 recipients developed evidence of Coccidioides infection, 2 of whom had disseminated disease. The degree of T-cell immunosuppression and timing of antifungal therapy initiation likely contributed to development of disease and disease severity in these recipients. This case series highlights the importance of having a high index of suspicion for Coccidioides infection in solid organ transplant recipients, even if the donor does not have known exposure, given the difficulties of obtaining a detailed and accurate travel history from next-of-kin.