Wooden sticks for plaque streaking and microbiological inoculation might be more cost- effective, but is its large scale use feasible? Quality control methods and proof of concept / Métodos de controle de qualidade e prova de conceito para a utilização de palitos de madeira em microbiologia podem ser mais econômicas, mas seu uso em larga escala é viável? Método de controle de qualidade e prova de conceito

The loop is a material classically used in the laboratory for the purpose of plate streaking and handling biological materials. However, metal loops techniques might be time consuming, considering the amount of time spent to guarantee its cooling process through each inoculation. Furthermore, plastic loops may also represent environmental issues during its production and discard process and can also represent higher costs for the laboratory. Thus, in situations of limited resources, even the simplest materials can be restricted due to logistical and budgetary issues, especially in developing countries. Inspired by demands like these, facing an occasional shortage of supply of laboratory plastic handles, we hereby present a quality control for sterilization methods and cost-effectiveness studies towards the use of wooden sticks in a Latin American country and we discuss the possibility of the large-scale use of this technique.

A alça calibrada é um material usado classicamente em laboratório para fins de inoculação em placas e manuseio de materiais biológicos. No entanto, as técnicas de alças metálicas podem consumir muito tempo, considerando a quantidade de tempo gasto para garantir seu processo de resfriamento a cada inoculação. Além disso, alças de plástico também podem representar questões ambientais durante o processo de produção e descarte e também podem representar custos mais altos para o laboratório. Assim, em situações de recursos limitados, até os materiais mais simples podem ser restringidos devido a questões logísticas e orçamentárias, especialmente nos países em desenvolvimento. Inspirados por demandas como essas, diante de uma escassez ocasional de suprimentos de alças de plástico de laboratório, apresentamos um controle de qualidade para métodos de esterilização e estudos de custo-efetividade para o uso de varas de madeira em um país latino-americano e discutimos a possibilidade de grande uso em escala dessa técnica.

A simple, efficient and cost-effective method for medium- to longterm maintenance and storage of Mycobacterium abscessus complex organisms.

Traditional culture of non-tuberculous mycobacteria (NTMs) has involved egg-based formulations (Lowenstein-Jensen medium, Ogawa Egg medium) or defined media (Middlebrook formulations), which have disadvatages of composition complexity, availability and cost. Previously, the commercial agar formulation, Standard Plate Count (SPC) agar [Yeast extract 2.5 g/L, pancreatic digest of casein 5.0 g/L, glucose 1.0 g/L, agar 15.0 g/L, pH 7.0 ± 0.2 at 25 °C] has been shown to be an effective solid medium for the enumeration and laboratory manipulation of Mycobacterium abscessus complex organisms. Given its relative simplicity, commercial availability and inexpensive cost, we wished to evaluate its utility for the medium- to longterm maintenance/storage of these organisms. M. abscessus complex organisms (n = 33), were inoculated onto SPCA slopes and stored undistubed in the dark at ambient temperature for six months. Following this, slopes were broken out and culture of the NTM attempted. All slopes maintained NTM culture viability and were able to initiate growth six months later. We therefore advocate the cost-effective employment of SPCA slopes for the medium- to longterm maintenance of M. abscessus organisms, without the need for complex media, availability of sterile blood and requirements for continuous -80 °C freezing.

The profiling of microbiota in vaginal swab samples using 16S rRNA gene sequencing and IS-pro analysis.

BACKGROUND: 16S rRNA gene sequencing is currently the most common way of determining the composition of microbiota. This technique has enabled many new discoveries to be made regarding the relevance of microbiota to the health and disease of the host. However, compared to other diagnostic techniques, 16S rRNA gene sequencing is fairly costly and labor intensive, leaving room for other techniques to improve on these aspects. RESULTS: The current study aimed to compare the output of 16S rRNA gene sequencing to the output of the quick IS-pro analysis, using vaginal swab samples from 297 women of reproductive age. 16S rRNA gene sequencing and IS-pro analyses yielded very similar vaginal microbiome profiles, with a median Pearson's R2 of 0.97, indicating a high level of similarity between both techniques. CONCLUSIONS: We conclude that the results of 16S rRNA gene sequencing and IS-pro are highly comparable and that both can be used to accurately determine the vaginal microbiota composition, with the IS-pro analysis having the benefit of rapidity.

Number, type and cost of microbiological tests during HIV Pre-Exposure Prophylaxis: The experience of a French hospital.

BACKGROUND: Microbiological tests are required for individuals on HIV Pre-Exposure Prophylaxis (PrEP), but their real-life numbers, types and cost are poorly described. METHODS: Number, type, and results of microbiological tests performed in a Besançon Hospital-associated laboratory, France, from 2016 to 2019, in the setting of PrEP consultations were retrospectively collected. Costs were estimated by the current reimbursement rate set by the French national protection system. RESULTS: 756 consultations for PrEP initiation or follow-up of 135 persons were performed over 4 years. Among 3434 tests performed in the institution-associated laboratory, 1083 and 2351 were virological and bacteriological tests, respectively. Serology was predominant in virology (98% of virological tests), with HIV, HCV, and HBV screening as the 3 more frequent assays, whereas molecular biology was predominant in bacteriology (63.1% of bacteriological tests) with N. gonorrhoeae and C. trachomatis screening as leader assays. Agar-based culture accounted for 1% of bacterial tests. The global cost of microbiological tests was 45,983.20 euros, corresponding to a mean cost of 60.80 euros per consultation. Virological and bacteriological tests accounted for 37.7% and 62.3% of this budget, respectively. No seroconversion was observed for HIV or HCV. N. gonorrhoeae and C. trachomatis were detected at least once in 39.3% and 22.4% of individuals, respectively, with 15% of symptomatic episodes in both cases. Active syphilis infection was detected in 15.4% of individuals. CONCLUSIONS: Since numerous microbiological tests are required during PrEP, the availability of specific technical platforms should not be neglected by centers wishing to set up PrEP consultations.

Development and evaluation of loop-mediated isothermal amplification for detection of Yersinia pestis in plague biological samples.

BACKGROUND: Several tests are available for plague confirmation but bacteriological culture with Yersinia pestis strain isolation remains the gold standard according to the World Health Organization. However, this is a time consuming procedure; requiring specific devices and well-qualified staff. In addition, strain isolation is challenging if antibiotics have been administered prior to sampling. Here, we developed a loop-mediated isothermal amplification (LAMP) technique, a rapid, simple, sensitive and specific technique that would be able to detect Y. pestis in human biological samples. METHODS: LAMP primers were designed to target the caf1 gene which is specific to Y. pestis. The detection limit was determined by testing 10-fold serial dilution of Y. pestis DNA. Cross-reactivity was tested using DNA extracts from 14 pathogens and 47 residual samples from patients suffering from non-plague diseases. Specificity and sensitivity of the LAMP caf1 were assessed on DNA extracts of 160 human biological samples. Then, the performance of the LAMP caf1 assay was compared to conventional PCR and bacteriological culture. RESULTS: The detection limit of the developed Y. pestis LAMP assay was 3.79 pg/µl, similar to conventional PCR. The result could be read out within 45 min and as early as 35 minutes in presence of loop primer, using a simple water bath at 63°C. This is superior to culture with respect to time (requires up to 10 days) and simplicity of equipment compared to PCR. Furthermore, no cross-reactivity was found when tested on DNA extracts from other pathogens and human biological samples from patients with non-plague diseases. Compared to the gold standard, LAMP sensitivity and specificity were 97.9% (95% CI: 89.1%-99.9%) and 94.6% (95% CI: 88.6%-97.9%), respectively. CONCLUSION: LAMP detected Y. pestis effectively with high sensitivity and specificity in human plague biological samples. It can potentially be used in the field during outbreaks in resource limited countries such as Madagascar.

[Criterium pencil mines as an alternative to platinum rods (Inoclic) in achievement of the antibiogram in agar medium for countries with limited resources?] / Les mines de crayon pour critérium comme alternative aux tiges de platine (Inoclic) dans la réalisation de l'antibiogramme en milieu gélosé pour les pays à ressources limitées ?

The realization of the antibiotic susceptibility test in agar is the routine bacteriological examination for the determination and monitoring of bacterial susceptibility to antibiotics. In this study, we report the comparative results between pencil leads for criterium, as an alternative to platinum rods in the realization of the antibiotic susceptibility test. METHODOLOGY: Experimental study evaluating the comparability of the results between Criterium and Inoclic mines (by counting bacterial cells on agar after 5 successive dilutions of reason 10 from a bacterial suspension obtained after piercing through a colony; by measuring the inhibition diameters of 4 ATCC reference bacterial strains on an antibiogram in an agar medium) and evaluating the sterility of the criterium mines by culturing them on enriched broth (heart - brain type). RESULTS: 42 bacterial strains were used for bacterial cell counting. The results were of the same order of magnitude (107 CFU/mL) between Inoclic and criterium mines, for all strains and at all dilutions. The antibiotic susceptibility tests performed for the 4 reference strains by the Inoclics and criterium mines all complied (100%) with the expected limits for determining their sensitivity profile to the antibiotics tested. Compared to the bacterial growth inhibition diameters on antibiotic susceptibility tests, no intra-operator variability was observed, while significant inter-operator variability (both with Inoclic and 0.5 mm criterium mines) was observed with some strains and for inhibition diameters greater than 10 mm. The enriched broth cultures (BCC) and their subculture carried out on 10 criterium mines from 5 different batches were negative. CONCLUSION: Criterium mines seem to be a serious and less expensive alternative to Inoclic for the realization of antibiotic susceptibility testing in our resource-limited countries.

Assessment of the performance of CHROMagar KPC and Xpert Carba-R assay for the detection of carbapenem-resistant bacteria in rectal swabs: First comparative study from Abu Dhabi, United Arab Emirates.

OBJECTIVES: The objective of this study was to evaluate the performance of CHROMagar™ KPC compared with Xpert® Carba-R assay for the detection of carbapenem-resistant bacterial isolates from rectal swabs. METHODS: Rectal swabs were obtained from patients admitted to Cleveland Clinic Abu Dhabi (United Arab Emirates) over a period of 7 months and were screened for carbapenem resistance by either culture on CHROMagar KPC or carbapenemase production using the Xpert Carba-R molecular method. Further testing for carbapenem susceptibility of isolates recovered from CHROMagar KPC was performed using VITEK®2. RESULTS: A total of 1813 rectal swabs were screened, of which 61 (3.4%) were positive for carbapenem resistance by either one or both methods. Both methods were equally efficient in detecting carbapenem resistance in 37/61 swabs (60.7%), mostly positive for Klebsiella pneumoniae (22 isolates), of which 40.9% (9/22) carried blaOXA-48-like and blaNDM. Xpert Carba-R assay detected 12 additional swabs with negative CHROMagar KPC culture and revealed additional carbapenemase-producing organisms carrying blaOXA-48-like and/or blaNDM. CHROMagar KPC recovered organisms in nine swabs not detected by the genotypic method, 44.4% of which were K. pneumoniae. Three swabs yielded false-positive results (carbapenem-susceptible organisms) by both methods. Sensitivity and specificity were, respectively, 75.4% and 99.8% for CHROMagar KPC and 80% and 99.8% for Xpert Carba-R. CONCLUSION: This comparative study of CHROMagar KPC versus Xpert Carba-R in rectal swabs showed a slightly higher sensitivity for the PCR-based method. Whilst CHROMagar KPC provides a less expensive screening method, Xpert Carba-R may be more accurate and faster.

A Cost-Effective Method for Identifying Enterobacterales with OXA-181.

OXA-181 is the second most common global OXA-48-like carbapenemase and is endemic in the Indian subcontinent. Molecular studies have shown that Enterobacterales with OXA-181 are often introduced into regions of nonendemicity. Distinguishing OXA-181 from other OXA-48-like enzymes often requires sequencing, which is rather expensive and time-consuming. A specific PCR (i.e., OXA181PCR) for the detection of blaOXA-181 was validated using a global collection (n = 315) of bacteria with well-characterized carbapenemases and showed 100% sensitivity and specificity (95% confidence interval [CI], 94.1 to 100 and 98.6 to 100, respectively) for detecting bacteria with OXA-181. The OXA181PCR subsequently gave positive results on 58/160 (36%) Enterobacterales with OXA-48-like carbapenemases from the 2015 INFORM surveillance program. The blaOXA-181-positive Enterobacterales were present in 9 countries spanning 5 continents, illustrating the global distribution of OXA-181. This methodology can easily be incorporated into molecular surveillance programs to provide accurate information about the prevalence of OXA-181. A loop-mediated isothermal amplification (LAMP)-OXA48 assay overall performed well for detecting OXA-48-like enzymes but showed poor specificity due to false-positive results with non-OXA carbapenemases.

Clinical Microbiology in Underresourced Settings.

The article discusses the environment of laboratory diagnostic bacteriology testing in several underresourced settings experienced by the author. The major global infectious diseases are usually managed with government or donor-supported systems, whereas basic laboratory testing for bacterial infections has no formal global programs. The causes of many of those diseases can be detected using simple manual bacteriologic methods available in most resource-limited environments; however, the challenges of building laboratory capacity in those settings are many. Positive and negative aspects of developing such capacities in selected locations are presented.

The cost-effectiveness of the use of selective media for the diagnosis of melioidosis in different settings.

BACKGROUND: Melioidosis is a frequently fatal disease requiring specific treatment. The yield of Burkholderia pseudomallei from sites with a normal flora is increased by culture using selective, differential media such as Ashdown's agar and selective broth. However, since melioidosis mainly affects people in resource-poor countries, the cost effectiveness of selective culture has been questioned. We therefore retrospectively evaluated this in two laboratories in southeast Asia. METHODOLOGY/PRINCIPAL FINDINGS: The results of all cultures in the microbiology laboratories of Mahosot Hospital, Vientiane, Laos and Angkor Hospital for Children, Siem Reap, Cambodia, in 2017 were reviewed. We identified patients with melioidosis who were only diagnosed as a result of culture of non-sterile sites and established the total number of such samples cultured using selective media and the associated costs in each laboratory. We then conducted a rudimentary cost-effectiveness analysis by determining the incremental cost-effectiveness ratio (ICER) per DALY averted and compared this against the 2017 GDP per capita in each country. Overall, 29 patients in Vientiane and 9 in Siem Reap (20% and 16.9% of all culture-positive patients respectively) would not have been diagnosed without the use of selective media, the majority of whom (18 and 8 respectively) were diagnosed by throat swab culture. The cost per additional patient detected by selective culture was approximately $100 in Vientiane and $39 in Siem Reap. Despite the different patient populations (all ages in Vientiane vs. only children in Siem Reap) and testing strategies (all samples in Vientiane vs. based on clinical suspicion in Siem Reap), selective B. pseudomallei culture proved highly cost effective in both settings, with an ICER of ~$170 and ~$28 in Vientiane and Siem Reap, respectively. CONCLUSIONS/SIGNIFICANCE: Selective culture for B. pseudomallei should be considered by all laboratories in melioidosis-endemic areas. However, the appropriate strategy for implementation should be decided locally.

[Incremental cost-effectiveness of the second Xpert MTB/RIF assay for detection of Mycobacterium tuberculosis].

Objective: To study the incremental cost-effectiveness of the second Xpert assay in detection of Mycobacterium tuberculosis (Mtb) and rifampicin (RIF) resistance. Methods: We continuously collected 2 896 specimens from suspected tuberculosis patients who had undergone 2 Xpert tests in a week from March 2015 to March 2018, including 2 402 suspected tuberculosis patients with 1 523 males and 879 females, with an average age of 50 years. Among them, 2 144 specimens of sputum and 258 cases of bronchoalveolar lavage fluid were collected. We also enrolled 494 patients with suspected extrapulmonary tuberculosis, 318 males and 176 females, with an average age of 42 years. Among them, 157 pleural effusion specimens, 106 cerebrospinal fluid specimens, 34 urine specimens and 197 pus specimens were collected. All specimens were subjected to two Xpert tests, smear microscopy, liquid rapid culture (BACTEC MGIT 960), and positively cultured bacteria were tested for drug susceptibility. Results: Among the 2 896 specimens from suspected tuberculosis patients, either one of the two Xpert test results was positive (including both tests were positive, the same below) in 1 639 patients, and 1 502 (91.6%) were positive in the first Xpert tests. The additional 137 (8.4%) test results were positive in the second tests. According to the smear test results, all specimens were divided into the smear negative group and the smear positive group. The second Xpert test was significantly higher than the smear-positive group (14.86%, 3.2%, P<0.001), and the extrapulmonary tuberculosis group was higher than the tuberculosis group (11.2%, 8.0%, P=0.12).Of the susceptibility test results, a total of 371 were rifampicin-resistant specimens. The first Xpert detected 91.4% (339/371), and the second Xpert detected the additional 8.1% (30/371).The cost increase of the second test was very significant. Tests were calculated at 650 yuan per time, the tuberculosis group was 1 184 yuan and 13 696 yuan(P<0.001); the extrapulmonary tuberculosis group was 1 755 yuan and 13 961 yuan(P<0.001). In the test of specimens of tuberculosis and extrapulmonary tuberculosis, the smear-negative specimen cost increase of the second Xpert test was lower than that of the smear-positive specimen. Conclusion: The second xpert test showed significant value-added cost-effectiveness in the diagnosis of tuberculosis.

Comparison of five methods for detection of carbapenemases in Enterobacterales with proposal of a new algorithm.

OBJECTIVES: The aim of this study was to evaluate the performance of five different carbapenemase tests and to develop an algorithm which will permit the detection of most common and rare carbapenemases in routine microbiology laboratories. METHODS: The immunochromatographic tests CARBA-5 (NG), RESIST-4 O.K.N.V. (Coris), the colorimetric ß-CARBA (BioRad), a newly developed carbapenem-inactivation method (CIM) supplemented with zinc (zCIM), and the Xpert Carba-R (Cepheid) were challenged with a collection of 189 molecularly characterized Enterobacterales isolates, including 146 carbapenemase producers (CPE): VIM (n = 48), OXA-48-like (n = 40), NDM (n = 29), KPC (n = 13), IMI (n = 9), IMP (n = 9), OXA-58 (n = 2), and GES (n = 2). RESULTS: The overall sensitivity/specificity values for the five carbapenemase detection tests were 84.2% (CI 77.6-89.2%)/100% (CI 91.8-100%) for RESIST-4, 88.2% (CI 82.1-92.4%)/100% (CI 91.8-100%) for CARBA-5, 88.2% (CI 82.1-92.4%)/100% (CI 91.8-100%) for Xpert Carba-R, 73.7% (CI 66.2-80.0%)/100% (CI 93.4-99.0%) for ß-CARBA, and 97.4% (CI 87.9-99.6%)/97.7% (CI 87.9-99.6%) for zCIM. The four common carbapenemases (KPC, OXA-48-like, NDM, and VIM) were detected with ≥97.6% sensitivity by all tests except for ß-CARBA (76.6% (CI 68.4-83.2%)). IMI and GES were only detected by zCIM (sensitivity 90.9% (CI 62.3-98.4%)). Based on these results a new algorithm was developed, consisting of an immunochromatographic assay as the first test followed by zCIM, which allows detection of 99.3% of all carbapenemases assessed. CONCLUSIONS: Except for ß-CARBA, all methods showed excellent sensitivity/specificity for the detection of the four most frequent carbapenemases. With the new algorithm, rare variants can also be detected. It is rapid, simple, and inexpensive and can be performed in any microbiology laboratory, as no PCR equipment is required.

Switching from expectorated to induced sputum cultures for tuberculosis diagnosis reduces cost without increasing risk.

Active pulmonary tuberculosis testing with 3 expectorated sputa can increase isolation days and expenditures compared with 1 induced sputum. Six-month retrospective and prospective chart reviews were conducted, and a screening algorithm was phased into 2 hospital sites. With induced sputum testing, isolation decreased from 7 to 4 days (interquartile range, 4-3, P = .0135), and there was a cost savings of $7,275 per case, with no added harm.

Cost minimization analysis of line probe assay for detection of multidrug-resistant tuberculosis in Arkhangelsk region of Russian Federation.

BACKGROUND: The development of new diagnostic tools allows for faster detection of both tuberculosis (TB) and multidrug-resistant (MDR) TB and should lead to reduced transmission by earlier initiation of anti TB therapy. The research conducted in the Arkhangelsk region of the Russian Federation in 2012-14 included economic evaluation of Line Probe Assay (LPA) implementation in MDR-TB diagnostics compared to existing culture-based diagnostics of Löwenstein Jensen (LJ) and BacTAlert. Clinical superiority of LPA was demonstrated and results were reported elsewhere. STUDY AIM: The PROVE-IT Russia study aimed to report the outcomes of the cost minimization analysis. METHODS: Costs of LPA-based diagnostic algorithm (smear positive (SSm+) and for smear negative (SSm-) culture confirmed TB patients by Bactec MGIT or LJ were compared with conventional culture-based algorithm (LJ-for SSm- and SSm+ patients and BacTAlert-for SSm+ patients). Cost minimization analysis was conducted from the healthcare system, patient and societal perspectives and included the direct and indirect costs to the healthcare system (microscopy and drug susceptibility test (DST), hospitalization, medications obtained from electronic medical records) and non-hospital direct costs (patient's travel cost, additional expenses associated with hospitalization, supplementary medicine and food) collected at the baseline and two subsequent interviews using the WHO-approved questionnaire. RESULTS: Over the period of treatment the LPA-based diagnostic corresponded to lesser direct and indirect costs comparing to the alternative algorithms. For SSm+ LPA-based diagnostics resulted in the costs 4.5 times less (808.21 US$) than LJ (3593.81 US$) and 2.5 times less than BacTAlert liquid culture (2009.61 US$). For SSm- LPA in combination with Bactec MGIT (1480.75 US$) vs LJ (1785.83 US$) showed the highest cost minimization compared to LJ (2566.09 US$). One-way sensitivity analyses of the key parameters and threshold analyses were conducted and demonstrated that the results were robust to variations in the cost of hospitalization, medications and length of stay. CONCLUSION: From the perspective of Russian Federation healthcare system, TB diagnostic algorithms incorporating LPA method proved to be both more clinically effective and less expensive due to reduction in the number of hospital days to the correct MDR-TB diagnosis and treatment initiation. LPA diagnostics comparing conventional culture diagnostic algorithm MDR-TB was a cost minimizing strategy for both patients and healthcare system.

Comparative evaluation of Xpert MTB/RIF assay with multiplex polymerase chain reaction for the diagnosis of tuberculous meningitis.

BACKGROUND: Rapid and specific diagnosis of tuberculous meningitis (TBM) is of paramount importance to decrease morbidity and mortality. Therefore, the present study was undertaken to compare the efficacy of Xpert MTB/RIF assay (GXpert) and multiplex PCR (MPCR) using three targets (IS6110, MPB64 and protein B) for diagnosing tuberculous meningitis. METHODS: GXpert and MPCR were performed on cerebrospinal fluid samples of 225 patients out of which 80 were culture-positive confirmed cases of TBM, 100 were 'suspected' cases of TBM and 45 were non-TBM controls. rpoB gene sequencing was done for diagnosing rifampicin (Rif) resistance in all positive cases. RESULTS: GXpert and MPCR were positive in 91/180 (50.5%) and 157/180 (87.2%) confirmed or suspected TBM patients respectively. Both the tests were negative in all 45 controls. Rif resistance was detected in 14 cases by GXpert and in 13 cases by MPCR. Rif resistance was confirmed in 13 cases with rpoB gene sequencing. There was one case of false Rif resistance detected by GXpert which was Rif susceptible on rpoB gene sequencing. Cost of doing MPCR was less than USD1 whereas GXpert required USD10 per isolate. CONCLUSION: MPCR has a higher sensitivity than GXpert for diagnosing TBM. MPCR is a robust and cost effective method for diagnosis of TBM in low-resource and high-endemic countries.

The 3-day rule for stool cultures: should all patients with haematological malignancies be excluded?

OBJECTIVES: The '3-day rule' for stool culture ordering suggests that only selected inpatients with nosocomial diarrhoea should have stool cultures for enteropathogenic bacteria (EPBs). Patients with haematological malignancies are not included in this group. We have analysed the ordering of stool cultures at Laikon Hospital to investigate whether all patients with haematological malignancies should be excluded from the 3-day rule. METHODS: We have retrospectively analysed all inpatient stool specimens sent to the microbiology laboratory for enteropathogenic bacteria culture at Laikon Hospital, Athens, Greece, between January 1, 2014 and December 31, 2014. We classified stool cultures sent after the third day as 'appropriate', 'excluded' with standard rule, 'excluded' with haematological malignancies, and 'inappropriate'. RESULTS: During the study period, 1101/1593 inpatient stool cultures (69.1%) had been ordered after the third day of hospitalization. The total yield for inpatient EPB stool cultures was 0.7% (11/1593). The yield for 'appropriate' cultures was significantly higher than the yield of all 'excluded' specimens (3.7% (3/81) versus 0.3% (2/585), p 0.018) and to 'inappropriate' orders (3.7% (3/81) versus 0.0% (0/485), p 0.0028). There was no difference in the yield between specimens 'excluded' with the standard rule and 'excluded' with haematological malignancies. CONCLUSIONS: In our hospital, the yield of stool cultures from patients with haematological malignancies is similar to that of patients 'excluded' from the standard 3-day rule. If patients with haematological malignancies were not excluded from the rule, we would reduce the inpatient stool cultures by 13.6% (217/1593) at the cost of missing one positive stool culture.

Detection of Bacteria in Water with ß-Galactosidase-Coated Magnetic Nanoparticles.

Pathogenic contamination and resistant bacterial infections remain critical concerns in both developed and developing countries. Rapid and sensitive detection of pathogens is still a key requirement for both environmental and clinical settings. This article introduces a simple, colorimetric, cost-effective, and high-throughput system based on a positively charged iron oxide/enzyme complex for the detection of both gram-positive and gram-negative bacteria in water between 103 and 108 cfu/mL. This study provides an effective strategy for the identification and purification of pathogen contamination in drinking water.

Comparative analysis of four commercial on-farm culture methods to identify bacteria associated with clinical mastitis in dairy cattle.

Several multiple-media culture systems have become commercially available for on-farm identification of mastitis-associated pathogens. However, the accuracy of these systems has not been thoroughly and independently validated against microbiological evaluations performed by referral laboratories. Therefore, the purpose of the present study was to evaluate the performance of commercially available culture plates (Accumast, Minnesota Easy System, SSGN and SSGNC Quad plates) to identify pathogens associated with clinical mastitis in dairy cows. Milk samples from the affected quarter with clinical mastitis were aerobically cultured with the on-farm culture systems and by two additional reference laboratories. Agreeing results from both standard laboratories were denoted as the reference standard (RS). Accuracy (Ac), sensitivity (Se), specificity (Sp), positive and negative predictive values (PPV and NPV, respectively) and Cohen's kappa coefficient (k) of on-farm plates were determined based on the RS culture of 211 milk samples. All four plate-systems correctly identified ≥ 84.9% of milk samples with no bacterial growth. Accumast had greater values for all overall predictive factors (Ac, Se, Sp, PPV and NPV) and a substantial agreement (k = 0.79) with RS. The inter-rater agreements of Minnesota, SSGN, and SSGNC with RS were moderate (0.45 ≤ k ≤ 0.55). The effectiveness to categorize bacterial colonies at the genus and species was numerically different amongst the commercial plates. Our findings suggest that Accumast was the most accurate on-farm culture system for identification of mastitis-associated pathogens of the four systems included in the analysis.