Concentration dependent exposure of vancomycin and teicoplanin induces vanG regulon in Staphylococcus aureus

Therapeutic options for staphylococcus infections have been raised due to the emergence of VISA and VRSA. Six isolates of Staphylococcus aureus of clinical origin which were previously confirmed to carry vanG were selected for this study. Antimicrobial susceptibility was performed by disc diffusion method. Transcriptional expression of vanG and vanSG showed down regulation against vancomycin and teicoplanin but expression was increased with increasing concentration of antibiotics. vanUG, vanRG showed up regulation against glycopeptide exposure. The present study underscored that expression of vanG and its regulatory gene operons are dependent on concentration of vancomycin and teicoplanin exposure in S.aureus.

Transcriptional Response of vanB Operon in Staphylococcus aureus Against Vancomycin and Teicoplanin Stress

Staphylococcus aureus is a global pathogen and is responsible for causing severe life-threatening infections. The current study was designed to investigate transcriptional expression of different core, regulatory, and accessory genes within vanB operon under differential exposure of vancomycin and teicoplanin. Four isolates selected for the study, were confirmed to harbour vanB gene in which three isolates showed MIC breakpoint above 16 µg/ml and one isolate above 8 µg/ml against vancomycin while teicoplanin showed higher MIC breakpoint as compared to vancomycin. Antibiotic susceptibility results showed that these isolates were susceptible towards imipenem and linezolid. Transcriptional expressional analysis of the core gene of vanB operon showed that expression of vanB is increased under vancomycin stress but is inversely proportional to increase in the concentration of the vancomycin while under teicoplanin stress the expression of vanB showed no significant pattern. Similar expressional pattern was found for vanH gene for both the glycopeptides. In case of vanX, expression was significantly increased at 1 µg/ml exposure of vancomycin, however, no pattern could be observed in case of teicoplanin stress. In case of regulatory gene, vanR, significant increase in expression was observed under vancomycin and teicoplanin stress of 1 µg/ml, however vanS, showed significant increase in the expression under 1 µg/ml of vancomycin. The accessory gene, vanY showed marginal increase in expression under both the antibiotic, while in case of vanW, the expressional pattern was found to be inversely proportional to the increasing antibiotic concentration.

Transcriptional analysis of prsA and vraTS regulatory system in methicillin resistant Staphylococcus aureus against oxacillin stress

PURPOSE

The prsA and vraTSR regulatory systems play a unique role in methicillin resistance by modifying the peptidoglycan cell wall PBP2 and involving cell wall stress response in Staphylococcus aureus. This study was designed to observe the transcriptional response of prsA and vraTSR system under oxacillin stress in S.aureus.

METHODS

In this study, three clinical isolates of Staphylococcus aureus and a laboratory strain were examined. All the isolates were tested for mecA gene by PCR assay and were also tested for prsA, vraT, vraS and vraR gene. The transcriptional responses of the prsA gene along with the vraTSR regulatory system in these isolates was observed under normal conditions and exposed to 2 ​μg/ml and 4 ​μg/ml of oxacillin stress by quantitative real-time PCR assay.

RESULTS

The result of transcriptional analysis confirmed that under oxacillin stress, the expressions of vraS and vraT are increased with the increase in the concentration of oxacillin. However, prsA has shown no significant expression under oxacillin stress.

CONCLUSION

Although prsA did not show any specific expressional pattern, the study highlights the role of vraS and vraT regulatory system in conferring a methicillin-resistant phenotype when exposed to subinhibitory concentrations of oxacillin, which could act as a potential target for the next-generation antimicrobials.

Distribution of carbapenem resistant Acinetobacter baumannii with blaADC-30 and induction of ADC-30 in response to beta-lactam antibiotics

A wide range of intrinsic Acinetobacter-derived cephalosporinases (ADC) along with other carbapenemases has now been detected in Acinetobacter baumannii leaving clinicians with few treatment options. The present study reports the spread of ADC-30 co-producing KPC-2 along with other β-lactamases among carbapenem resistant A. baumannii strains obtained from ICU patients in two Indian hospitals. Primer extension analysis revealed higher transcript level of the ADC gene when induced with cefoxitin at 8 μg/ml (170 fold), ceftriaxone at 8 μg/ml (136 fold), ceftazidime at 4 μg/ml (65 fold), cefepime at 8 μg/ml (77 fold) and aztreonam at 8 μg/ml (21 fold) when compared with the basal level without antibiotic pressure. Slight increase in expression of bla_ADC-30 when induced with imipenem and meropenem at 0.25 μg/ml (3 and 6 fold) was observed and may help in conferring resistance to carbapenem. MLST analysis revealed the circulation of A. baumannii sequence types ST188, ST386, ST583 and ST390 in these hospitals.

Starch-templated bio-synthesis of gold nanoflowers for in vitro antimicrobial and anticancer activities

We describe an in situ method of synthesizing highly branched gold nanoflower (AuNFs) using aqueous seed extract of Syzygium cumini (L.) Skeels as reductant in the presence of 0.3% starch. Surprisingly, when the same reaction was carried out in the absence of starch or with starch at a lower concentration (0.15%), instead of flower-like morphology quasi-spherical or polyhedral nanoparticles (AuNPs) are obtained. The nanomaterials were extensively characterized by HRTEM, FESEM, UV–Vis, FTIR, XRD, XPS and TGA analysis. The biological activities of the materials were investigated for antimicrobial activities against four bacterial strains that include one Gram positive (Staphylococcus aureus MTCC 121), two Gram negative (Escherichia coli MTCC 40 and Pseudomonas aeruginosa MTCC 4673) and one fungi (Candida albicans MTCC 227). The nanoparticles functioned as effective antimicrobial and anti-biofilm agents against all the strains under study. Controlled study revealed that, the AuNFs showed improved efficacy over conventional polyhedral AuNPs against all the microbes under study which might be attributed to the larger surface-to-volume ratio of the nanoflowers. The AuNFs also showed effective in vitro anticancer activity against a human liver cancer cell line (HepG2) with no significant cytotoxicity. Our data suggest that the AuNFs can significantly reduce the cancer cell growth with IC50 value of 20 µg mL−1.

Effect of incorporation of fermented bamboo shoot on physicochemical and microbial quality of pork pickle

Replacement of commercial chemical preservative (Vinegar) by incorporating fermented bamboo shoot (FBS) products partially or completely and their effect on physicochemical, microbial and shelf life qualities on pork pickle products was studied. Different FBS products such as FBS extract, paste and powder were incorporated in the pork pickle products at the level of 50 to 100 % with or without vinegar and stored at room temperature for 90 days. Highest pH values and lowest titrable acidity was recorded in products with 50 and 100 % FBS powder. No significant differences were observed with respect to proximate composition i.e. percent moisture, protein, fat and ash contents among the products except the product with 100 % FBS powder which had significantly (p < 0.01) lower moisture content. Microbial load (Log total plate counts) and thiobarbituric acid (TBA) values were found to be increasing as the storage periods were advancing. Except the product with 100 % FBS powder which could be stored for 30 days only, other products could be stored upto 90 days without any physicochemical and microbial problems. It can be concluded from this study that natural and organic FBS extract and paste can be used successfully replacing the conventional chemical preservative (Vinegar) for preparation of pork pickle products and preserved more than 90 days at room temperature. However, FBS powder can be used for preservation of the pickle products for a short period (30 days).

Understanding Darjeeling tea flavour on a molecular basis

Darjeeling teas are the highest grown teas in the world and preferred for its flavour, aroma and quality. Apart from the genetic makeup of the plant, earlier reports suggest that insect infestation, particularly jassids and thrips triggers the aroma and flavour formation in Darjeeling tea. The present work encompasses the identification of the genes/transcriptomes responsible for the typical flavour of Darjeeling tea, besides understanding the role of jassids and thrips in particular, in producing the best cup character and quality. The quantitative real time PCR analysis was based on a suppression subtractive hybridisation forward library of B157 (tea clone infested with thrips), providing us transcripts related to aroma and flavour formation. We observed the expression of genes like leucine zipper, ntd, nced, geraniol synthase, raffinose synthase, trehalose synthase, amylase, farnesyl transferase, catalase, methyl transferase, linalool synthase, peroxidases, elicitor responsive proteins, linamarase, nerolidol linalool synthase 2, 12-oxophytodienoate reductase, glucosidase, MYB transcription factor, and alcohol dehydrogenase, highly regulated due to insect infestation, manufacturing stresses and mechanical injury. The first report on gene expression dynamics in thrips infested Darjeeling tea leaves can be extrapolated with increase in volatiles which is responsible for enhancing the quality of Darjeeling tea, specially the flavour and aroma of the infusion. We hope to model these responses in order to understand the molecular changes that occur during Darjeeling tea flavour formation.

Effect of incorporation of chicken blood plasma on physico-chemical properties of cakes

Level of inclusion of chicken blood plasma (CBP) in the preparation of cakes was assessed in respect of certain physico-chemical quality traits. The cakes were prepared with and without added flavour. In each group, seven cakes were prepared from 0 (control) to 60% level of inclusion of CBP with 10% interval. The cakes at 40% level of incorporation of CBP recorded highest visual grades for colour and consistency. There was gradual rise in cake volume up to 40% level and on further increase in level of inclusion of CBP resulted into subsequent fall in cake volumes. The pH of cakes did not differ significantly up to 20% level but it increased beyond 20%. The moisture, total ash and crude protein contents of cakes exhibited an increasing trend from 0 to 60% level of inclusion of CBP. The ether extract of cakes showed a gradual decrease at increased level of inclusion of CBP. There was no significant effect of flavour for all the parameters studied. Based on the overall results, it may be concluded that CBP could be successfully used up to 30% level of inclusion for value addition in egg products.

An analysis of deficiencies identified during investigational new drug (IND) application reviews by the Division of Drug Oncology Products (DDOP) of the US FDA

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Background: Regulations require IND application review by the FDA prior to initiation of the clinical study. Deficiencies identified in the study protocol require communication between the FDA reviewers and the Sponsor for resolution. If the deficiencies are not adequately resolved, clinical hold and subsequent delay in the start of the clinical study results. To identify and analyze the commonly encountered IND application deficiencies, data from recent reviews were collected. Methods: Eight clinical reviewers analyzed the deficiencies that had been identified in 268 IND applications reviewed in the DDOP FDA from January 2003 to June 2005. All of the study protocol deficiencies leading to a clinical hold, or requiring resolution prior to study initiation were categorized as deficiencies pertaining to: patient eligibility; starting drug dose; study conduct (toxicity management, dose adjustment, stopping criteria); statistical or endpoints; non-clinical; and other issues. Results: 268 IND applications reviewed over a 30-month period by eight medical officers were analyzed. One hundred and twelve (42%) of the applications had no deficiencies; however, 156 (58%) had one (31%) or multiple (69%) deficiencies. Deficiencies pertained to study conduct/scheme (65%), dose (48%), patient eligibility (46%), others (31%), statistics or endpoints (15%), and non-clinical (4%) issues. In 141 (90%) of the deficient applications the deficiencies were adequately addressed by FDA reviewer-Sponsor communication and the trials could start as scheduled. Fifteen (10%) deficient trials were placed on clinical hold. Fourteen (93%) of these trials had multiple deficiencies that pertained to patient eligibility in 12 (80%), starting drug dose in 12 (80%), study conduct in 11 (73%), other in 7 (47%), and non-clinical and statistical issues in 2 (13%) each. Conclusions: Deficiencies were identified in 58% of the reviewed IND applications: 90% of these were resolved by FDA-Sponsor communication. Only 10% of deficient studies were placed on clinical hold; all except one had multiple deficiencies. The most common deficiencies leading to clinical hold pertained to eligibility of study population and proposed starting drug dose.

No significant financial relationships to disclose.

Endoscopic KTP-532 laser assisted diverticulotomy for Zenker's diverticulum

Zenker's diverticulum, though counnon in western countries is uncommon in India. This diverticuham is an extension of umcosa through Killian's dehiscence. Various surgical methods have been described for the treatment of this condition including the use of lasers but none in Indian Journals. In this paper we describe a case of Zenker's diverticulum where diverticulotomy using KTP532 laser was successfully performed. Its advantages over other techniques are mentioned.

Standardisation of quantitative direct gas liquid chromatography for early detection of bacteria in blood cultures

Blood cultures with strains of aerobic, facultative and obligate anaerobic bacteria were studied by quantitative direct gas liquid chromatography for early diagnosis of bacteraemias. Small amounts of volatile and nonvolatile fatty acids were detected in uninoculated blood cultures. Bacteroides fragilis produced acetic (27.6 mumol/ml), propionic (1.0 mumol/ml), isovaleric, (0.6 mumol/ml), lactic (4.5 mumol/ml) and succinic (2.7 mumol/ml) acids after 48 h. Blood cultures inoculated with Clostridium perfringens and Fusobacterium nucleatum produced large amount of butyric acid (2.5 and 18.8 mumol/ml respectively) along with acetic, propionic, lactic and succinic acids on day 2 of incubation. Blood cultures with Escherichia coli, Salmonella typhi, Staphylococcus aureus, beta-haemolytic streptococci (group A) produced only acetic, lactic and succinic acids. Pseudomonas aeruginosa produced only small amounts of succinic (0.6 mumol/ml) and acetic acids (2.4 mumol/ml) on day 5 of incubation. Blood cultures inoculated with anaerobic bacteria produced multiple volatile fatty acids within 24 to 48 h of incubation. Since these acids could be detected earlier than the organism in cultures, they may be useful in the early diagnosis of anaerobic bacteraemias/septicaemias.