Photo-induced high-temperature ferromagnetism in YTiO3.

In quantum materials, degeneracies and frustrated interactions can have a profound impact on the emergence of long-range order, often driving strong fluctuations that suppress functionally relevant electronic or magnetic phases1-7. Engineering the atomic structure in the bulk or at heterointerfaces has been an important research strategy to lift these degeneracies, but these equilibrium methods are limited by thermodynamic, elastic and chemical constraints8. Here we show that all-optical, mode-selective manipulation of the crystal lattice can be used to enhance and stabilize high-temperature ferromagnetism in YTiO3, a material that shows only partial orbital polarization, an unsaturated low-temperature magnetic moment and a suppressed Curie temperature, Tc = 27 K (refs. 9-13). The enhancement is largest when exciting a 9 THz oxygen rotation mode, for which complete magnetic saturation is achieved at low temperatures and transient ferromagnetism is realized up to Tneq > 80 K, nearly three times the thermodynamic transition temperature. We interpret these effects as a consequence of the light-induced dynamical changes to the quasi-degenerate Ti t2g orbitals, which affect the magnetic phase competition and fluctuations found in the equilibrium state14-20. Notably, the light-induced high-temperature ferromagnetism discovered in our work is metastable over many nanoseconds, underscoring the ability to dynamically engineer practically useful non-equilibrium functionalities.

Control of structure and spin texture in the van der Waals layered magnet CrSBr.

Controlling magnetism at nanometer length scales is essential for realizing high-performance spintronic, magneto-electric and topological devices and creating on-demand spin Hamiltonians probing fundamental concepts in physics. Van der Waals (vdW)-bonded layered magnets offer exceptional opportunities for such spin texture engineering. Here, we demonstrate nanoscale structural control in the layered magnet CrSBr with the potential to create spin patterns without the environmental sensitivity that has hindered such manipulations in other vdW magnets. We drive a local phase transformation using an electron beam that moves atoms and exchanges bond directions, effectively creating regions that have vertical vdW layers embedded within the initial horizontally vdW bonded exfoliated flakes. We calculate that the newly formed two-dimensional structure is ferromagnetically ordered in-plane with an energy gap in the visible spectrum, and weak antiferromagnetism between the planes, suggesting possibilities for creating spin textures and quantum magnetic phases.

Nanoscale lattice dynamics in hexagonal boron nitride moiré superlattices.

Twisted two-dimensional van der Waals (vdW) heterostructures have unlocked a new means for manipulating the properties of quantum materials. The resulting mesoscopic moiré superlattices are accessible to a wide variety of scanning probes. To date, spatially-resolved techniques have prioritized electronic structure visualization, with lattice response experiments only in their infancy. Here, we therefore investigate lattice dynamics in twisted layers of hexagonal boron nitride (hBN), formed by a minute twist angle between two hBN monolayers assembled on a graphite substrate. Nano-infrared (nano-IR) spectroscopy reveals systematic variations of the in-plane optical phonon frequencies amongst the triangular domains and domain walls in the hBN moiré superlattices. Our first-principles calculations unveil a local and stacking-dependent interaction with the underlying graphite, prompting symmetry-breaking between the otherwise identical neighboring moiré domains of twisted hBN.

Sub-national TB prevalence surveys in India, 2006-2012: Results of uniformly conducted data analysis.

SETTING: Community based tuberculosis (TB) prevalence surveys in ten sites across India during 2006-2012. OBJECTIVE: To re-analyze data of recent sub-national surveys using uniform statistical methods and obtain a pooled national level estimate of prevalence of TB. METHODS: Individuals ≥15 years old were screened by interview for symptoms suggestive of Pulmonary TB (PTB) and history of anti-TB treatment; additional screening by chest radiography was undertaken in five sites. Two sputum specimens were examined by smear and culture among Screen-positives. Prevalence in each site was estimated after imputing missing values to correct for bias introduced by incompleteness of data. In five sites, prevalence was corrected for non-screening by radiography. Pooled prevalence of bacteriologically positive PTB was estimated using Random Effects Model after excluding data from one site. Overall prevalence of TB (all ages, all types) was estimated by adjusting for extra-pulmonary TB and Pediatric TB. RESULTS: Of 769290 individuals registered, 715989 were screened by interview and 294532 also by radiography. Sputum specimen were examined from 50 852 individuals. Estimated prevalence of smear positive, culture positive and bacteriologically positive PTB varied between 108.4-428.1, 147.9-429.8 and 170.8-528.4 per 100000 populations in different sites. Pooled estimate of prevalence of bacteriologically positive PTB was 350.0 (260.7, 439.0). Overall prevalence of TB was estimated at 300.7 (223.7-377.5) in 2009, the mid-year of surveys. Prevalence was significantly higher in rural compared to urban areas. CONCLUSION: TB burden continues to be high in India suggesting further strengthening of TB control activities.

Sensitivity and specificity of screening tools and smear microscopy in active tuberculosis case finding.

SETTING: Community based five pulmonary tuberculosis (PTB) surveys among adults. OBJECTIVES: Estimate sensitivity and specificity of screening tools for PTB and sputum microscopy. METHODS: For each survey site, we estimated sensitivity and specificity of different screening criteria and microscopy against culture; pooled estimates were obtained using Random Effects Model. RESULTS: Sensitivity of cough alone, screening for any symptom (persistent cough ≥2 weeks, fever or chest pain ≥1 month, hemoptysis), any symptom or history of anti-TB treatment (h/o ATT) were 56.2%, 66% and 71.2% respectively; specificities were 95.3%, 93.8% and 92.7% respectively. X-ray when used alone for primary screening had sensitivity and specificity of 76.6% and 97.3% respectively. When used along with screening for cough, these figures were 94.3% and 93.1%, and 100% and 97.3% when used with any symptom and h/o ATT. When used for secondary screening, sensitivity and specificity of X-ray was 66.8% and 87.8% respectively after primary screening for cough, 65.0% and 89.8% after screening for any symptom, and 67.1% and 86.7% when used after screening for any symptom or h/o ATT. Pooled sensitivity and specificity of smear was 46.2% and 99.3% respectively. CONCLUSION: Program managers may use these estimates while evaluating algorithms for active case finding.

Drug susceptibility of rapid and slow growing non-tuberculous mycobacteria isolated from symptomatics for pulmonary tuberculosis, Central India.

BACKGROUND: Non-tuberculous mycobacteria (NTM) are emerging as important pathogens. Their treatment also differs from that of Mycobacterium tuberculosis. In India, any datum on them is scarce as species identification and drug susceptibility are not performed in most laboratories. Susceptibility also differs from one geographic area to another, and in our country, there are no data even to guide the clinicians to start treatment empirically. METHODOLOGY: The present study endeavours to generate drug susceptibility data on NTM isolated from sputum samples collected and stored from 6445 symptomatics for pulmonary tuberculosis during a prevalence survey and from specimens received from the hospital. Isolates were not necessarily associated with the disease. Species were identified and antibiotic susceptibility was performed using micro-broth dilution technique as per the standard Clinical and Laboratory Standards Institute guidelines. RESULTS: A total of 65 NTM with 11 species were identified, of which 27 belonged to Mycobacterium fortuitum complex, 14 Mycobacterium gordonae, 9 Mycobacterium avium, 7 Mycobacterium flavescens, 4 Mycobacterium scrofulaceum and one each of others. Sensitivity to amikacin for M. fortuitum was 95.22% (20 out of 21), followed by ciprofloxacin (76.19%) and clarithromycin (71.42%). All the 9 M. avium isolates, 11 of M. gordonae (78.57%), 5 of M. flavescens and 2 of M. scrofulaceum were sensitive to clarithromycin. All NTM were resistant to first-line antitubercular drugs except 8, which were sensitive to streptomycin. CONCLUSIONS: Drug sensitivity of NTM varies from species to species. While amikacin was the best for rapidly growing mycobacteria, clarithromycin was the most active drug against M. avium and other slow growers.

Evaluation of variants of carbol fuchsin solution to stain acid-fast bacilli in-situ by the pot method.

BACKGROUND: Ziehl-Neelsen (ZN) staining requires heating, and pre-stained smears contain viable bacilli. OBJECTIVE: To evaluate four variants of carbol fuchsin solution by the pot method and compare the results with ZN staining, taking culture as gold standard. METHOD: Five hundred sputum samples from presumptive tuberculosis cases were homogenised and divided into two parts. One part was subjected to routine ZN staining and culture on solid medium, the other was equally distributed into four pots. Equal quantities of the basic fuchsin (BF) variant were added to each pot. Variant I contained 2% BF with 10% phenol and 4% ammonium sulphate (PhAS), while Variant II had 0.6% BF with PhAS; Variants III and IV contained respectively 2% and 0.6% BF with 10% phenol only. After 1 h, smears were made from each pot and culture was performed on Löwenstein-Jensen medium. Smear results were compared with the ZN results and evaluated against culture. RESULTS AND CONCLUSION: Variant III gave excellent results compared to ZN (κ = 0.97), with sensitivity, specificity, and positive and negative predictive values similar to those of ZN, taking culture as gold standard. Pot contents were negative for Mycobacterium tuberculosis culture.

Comparision of Three Laboratory Tests for Detection of AmpC ß Lactamases in Klebsiella Species and E. Coli.

BACKGROUND AND OBJECTIVE: AmpC ß lactamases are one of the important causes of drug resistance in gram negative bacteria. Failure to detect these enzymes in the laboratory has contributed to therapeutic failures but there are till date no standard guideline available. This study was therefore undertaken to evaluate three phenotypic laboratory tests and the inhibitors used in two of the tests to detect AmpC ß lactamases produced by E. coli and Klebsiella species as they are most commonly isolated organisms. METHODS: E. coli and Klebsiella isolates from different clinical samples were tested for ESBLs production as per CLSI guidelines and excluded from the study. The non-ESBLs isolates were then screened for AmpC ß lactamases production, by cefoxitin and then confirmed by three different methods, i.e., Disc Potentiation Test (DPT) , Double Disc Synergy Test (DDST) and Modified Three Dimensional Test (M3DT) which in the absence of molecular methods, was taken as the gold standard. Boronic acid and cloxacillin were used as inhibitory agents in the Disc Potentiation and Double Disc synergy Tests. RESULTS: A total of 2,933 isolates were tested out of which 165 isolates were detected as non ESBLs producers,135 (81.82%) when screened for AmpC ß lactamases based on resistance to cefoxitin were labelled as positive. 30 (18.18%) cefoxitin sensitive isolates were labelled as probably non AmpC producers . M3DT, in addition to detecting all the 135 (100%) cefoxitin resistant isolates, also detected 5 (16.67%) cefoxitin sensitive isolates as AmpC producers. Other phenotypic tests, DPT and DDST with different inhibitors like boronic acid and cloxacillin in different potencies were all found to be less sensitive. The best results among these two methods were obtained with DDST using cloxacillin 500µg. CONCLUSION: In the absence of recommended guidelines for AmpC detection, the study reports, among the tests performed, M3DT as the best phenotypic method for AmpC confirmation, as it is not only the most sensitive but also specific test for AmpC as it rules out the resistance due to other mechanisms like the porin channel.

Correlation between measures of hypoglycemia and glycemic improvement in sulfonylurea treated patients with type 2 diabetes in India: results from the OBSTACLE hypoglycemia study.

BACKGROUND: This study aimed to assess correlation between measures of hypoglycemia and glycemic control in patients with type 2 diabetes mellitus (T2DM) treated with sulfonylureas. MATERIALS AND METHODS: T2DM patients being initiated on a sulfonylurea (SU) on background of a failing oral antihyperglycemic regimen were followed up for 12 weeks. (HbA1c) was measured at baseline and end of follow-up. Hypoglycemia was assessed using Stanford Hypoglycemia Questionnaire at week 12. RESULTS: Of the total 1069 patients enrolled, 950 were considered evaluable. A weak negative correlation was observed between end of follow-up HbA1c values and hypoglycemia score, using both linear regression analysis (correlation coefficient -0.12; P = 0.0002) and negative binomial regression (ß slope -0.09; P = 0.0010). A similar correlation was also observed between change in HbA1c from baseline and hypoglycemia score (ß slope -0.07; P = 0.0048). Mean HbA1c reduction was lowest (0.65 ± 2.27%) in patients not reporting any hypoglycemia and highest (1.28 ± 2.40%) in patients with hypoglycemia score greater than median of 2 (P = 0.0031). There was no correlation between hypoglycemia frequency and end of follow-up HbA1c values (P = 0.4111). CONCLUSION: With addition of SU on a background of a failing oral anti-hyperglycemic regimen, the extent of glycemic control correlates directly with measures of patient reported hypoglycemia.

Trends in the annual risk of tuberculous infection in India.

SETTING: Twenty-four districts in India. OBJECTIVES: To evaluate trends in annual risk of tuberculous infection (ARTI) in each of four geographically defined zones in the country. STUDY DESIGN: Two rounds of house-based tuberculin surveys were conducted 8-9 years apart among children aged 1-9 years in statistically selected clusters during 2000-2003 and 2009-2010 (Surveys I and II). Altogether, 184,992 children were tested with 1 tuberculin unit (TU) of purified protein derivative (PPD) RT23 with Tween 80 in Survey I and 69,496 children with 2TU dose of PPD in Survey II. The maximum transverse diameter of induration was measured about 72 h after test administration. ARTI was computed from the prevalence of infection estimated using the mirror-image method. RESULTS: Estimated ARTI rates in different zones varied between 1.1% and 1.9% in Survey I and 0.6% and 1.2% in Survey II. The ARTI declined by respectively 6.1% and 11.7% per year in the north and west zones; no decline was observed in the south and east zones. National level estimates were respectively 1.5% and 1.0%, with a decline of 4.5% per year in the intervening period. CONCLUSION: Although a decline in ARTI was observed in two of the four zones and at national level, the current ARTI of about 1% in three zones suggests that further intensification of TB control activities is required.

Detection of metallo-ß-lactamases producing Acinetobacter baumannii using microbiological assay, disc synergy test and PCR.

BACKGROUND: One leading factor responsible for resistance in Acinetobacter baumannii, an important opportunist in health care institutions globally, is the production of carbapenamases like metallo-ß-lactamases (MBLs), which hydrolyze a variety of ß-lactams including penicillin, cephalosporins and carbapenems. However, neither any standard guidelines are available nor any method has been found to be perfect for their detection. Various methods have shown discordant results, depending upon the employed methodology, ß-lactamase substrate and MBL inhibitor used. This study aims to evaluate two phenotypic methods against PCR as gold standard among carbapenem resistant A. baumannii for identifying MBL producers. MATERIALS AND METHODS: A total of 130 A. baumannii were screened for imipenem and meropenem resistance by Kirby-Bauer disc diffusion method. Phenotypic expression of MBL was detected by EDTA-imipenem-microbiological (EIM) assay and extended EDTA disc synergy (eEDS) test and presence of bla-IMP and bla-VIM was detected by PCR in all the carbapenem resistant isolates. RESULTS: Of the 43 imipenem and/or meropenem resistant A. baumannii isolates, 4 (9.3%) were found to be MBL producers by EIM and 3 (6.97%) by eEDS. Only bla-VIM gene was detected in 7 (16.28%) by PCR. In addition EIM detected 14 (32.56%) carbapenem resistant non-metallo enzyme producers. CONCLUSION: Of the two MBL genes targeted, bla-VIM was only detected and that too in isolates resistant to both imipenem and meropenem. Further, EIM was useful in differentiating MBL from non-metalloenzymes producers.

Comparison of disc and MIC reduction methods with polymerase chain reaction for the detection of metallo-ß-lactamase in Pseudomonas aeruginosa.

PURPOSE: The present study was undertaken to evaluate the screening antibiotic, confirmatory phenotypic test and agent against PCR as gold standard and to detect the prevalent MBL gene. MATERIALS AND METHODS: Three hundred and twenty-six Pseudomonas aeruginosa isolates were screened for resistance to Imipenem (IPM), Meropemem (MEM) and Ceftazidime (CAZ) by disc diffusion. Isolates resistant to any of these were considered screen test-positive for MBL and were subjected to Double disc synergy test (DDST) and Disc potentiation test (DPT: Using IPM, MEM and CAZ alone and with EDTA), Minimum inhibitory concentration (MIC) reduction [four-fold or more reduction in MIC of IPM and MEM in presence of chelators: EDTA and 1,10-phenanthroline (EPI/EPM: EDTA-phenanthroline- Imipenem/Meropenem Broth Microdilution method)] and polymerase chain reaction (PCR) for blaIMP and blaVIM . RESULTS: Screen test-positives by MEM and CAZ were 19.3% as against 17.8% by IPM. MEMDDST, DPT and EPM confirmed 100% screen-test positives as against 93.7% by CAZ DDST and DPT-2, 76.2% by CAZ DPT-1, 88.9% by IPM DDST, 85.7% by IPM DPT-1 and 92.1% by EPI. IPMand CAZ DDST together confirmed 100% while IPM and CAZ DPT-2 confirmed 96.8%. All 63 screen-test positives showed the presence of blaVIM . CONCLUSIONS: MEM was found to be the best screening and confirmatory agent for MBL detection and blaVIM was found to be the prevalent MBL gene in this part of the country.

Comparison of the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide tube method with the conventional method and real-time polymerase chain reaction for the detection of rifampicin resistance in Mycobacterium tuberculosis.

Colorimetric methods are cheap, reproducible, and rapid methods of detecting drug resistance in Mycobacterium tuberculosis. The MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) method is one such technique that has been established in our laboratory to detect rifampicin resistance. The present study compared the results of the MTT method with those of the proportion method and real-time polymerase chain reaction (RTPCR) in order to establish sensitivity and specificity of MTT. The mutations for rifampicin resistance occur in rpoB gene, and the commonest reported are in codons 526 and 531. Therefore, RTPCR was targeted at these two codons. The concordance of MTT with the proportion method and RTPCR was 94 and 72.77%, respectively, and that of RTPCR with the proportion method was 77.77%. While the study confirmed that the MTT method is a good method for detecting rifampicin resistance, it also brought out the fact that RTPCR when targeted for limited mutations is not a good tool. Either the genotypic method used should target the total 81-bp rpoB genome or methods such as DNA sequencing should be used. For resource-constraint laboratories, the MTT method can be considered as a better choice.

Management of choledochal cyst with portal hypertension.

Portal hypertension (PHT) is a rare complication associated with choledochal cysts. Management issues of PHT patients are inadequately addressed, as its incidence is low and underlying causes variable. We report three cases of choledochal cyst with PHT. All patients had type IVa choledochal cysts, and the causes of PHT were secondary biliary cirrhosis (SBC) (two cases) and alcoholic liver disease (one case). Clinical presentation included jaundice, gastrointestinal bleeding and ascites. One patient with SBC successfully underwent excision with Rouxen-Y hepaticojejunostomy, while the patient with cholangitis was managed with endoscopic retrograde cholangiopancreatography stenting. The last patient with alcoholic liver disease was managed conservatively for seven years and died of liver failure. Management of choledochal cysts depends on the severity of liver disease in cases of cirrhosis of unrelated cause, while those with SBC should be considered for surgical management. Endoscopic stenting may be considered as a temporary measure in high-risk cases.

Inducible clindamycin resistance in Staphylococcus aureus isolated from clinical samples.

PURPOSE: Clindamycin is commonly used in the treatment of erythromycin resistant Staphylococcus aureus causing skin and soft tissue infections. In vitro routine tests for clindamycin susceptibility may fail to detect inducible clindamycin resistance due to erm genes resulting in treatment failure, thus necessitating the need to detect such resistance by a simple D test on routine basis. MATERIALS AND METHOD: 247 Staphylococcus aureus isolates were subjected to routine antibiotic susceptibility testing including oxacillin (1ìg) by Kirby Bauer disc diffusion method. Inducible clindamycin resistance was detected by D test, as per CLSI guidelines on erythromycin resistant isolates. RESULTS: 36 (14.5%) isolates showed inducible clindamycin resistance, nine (3.6%) showed constitutive resistance while remaining 35 (14.1%) showed MS phenotype. Inducible resistance and MS phenotype were found to be higher in MRSA as compared to MSSA (27.6%, 24.3% and 1.6%, 4% respectively). CONCLUSION: Study showed that D test should be used as a mandatory method in routine disc diffusion testing to detect inducible clindamycin resistance.

Disseminated disease caused by Mycobacterium simiae in AIDS patients: a report of three cases.

Disseminated disease caused by Mycobacterium simiae, a slowly growing nontuberculous mycobacterium, has been rarely reported in the literature. We report on three AIDS patients who were found to suffer from mycobacteraemia caused by M. simiae in a rural tertiary-care hospital in central India.

Isolation and identification of nontuberculous mycobacteria from water and soil in central India.

Nontuberculous mycobacteria (NTM), important organisms in the Genus Mycobacterium and commonly present in the environment, are known to cause disseminated disease in AIDS patients. In this study, NTM were isolated from environment (soil and water) of the AIDS patients with disseminated NTM disease to know the prevalence of environmental NTM species and their correlation with clinical isolates from patients of the same area. Paraffin baiting technique was used to isolate NTM from environmental samples. Once isolated, subcultures were made on Lowenstein Jensen and Middlebrook 7H10 media and the species were identified using phenotypic and genotypic techniques. A total of 26 NTM isolates belonging to seven different species could be identified. Mycobacterium avium was the only species isolated from both clinical and environmental samples of the same patient; but the isolates did not match using PCR for IS 1311 and IS 1245 spacer sequences.

Status of high level aminoglycoside resistant Enterococcus faecium and Enterococcus faecalis in a rural hospital of central India.

Considering the emergence of high level aminoglycoside resistance (HLAR) in enterococci this study was undertaken to determine their status in a rural setting. HLAR by disc diffusion and agar dilution, beta lactamase by nitrocefin disc and vancomycin resistance by agar dilution was determined in 150 enterococcal isolates, as per NCCLS guidelines. Only two species, Enterococcus faecalis (85.5%) and Enterococcus faecium (14.7%) were recovered, mostly from blood. Forty six percent showed HLAR. Multi drug resistance and concomitant resistance of HLAR strains to beta lactams were quite high. None showed beta lactamase activity or vancomycin resistance.