Probing Synechocystis-Arsenic Interactions through Extracellular Nanowires

Microbial nanowires (MNWs) can play an important role in the transformation and mobility of toxic metals/metalloids in environment. The potential role of MNWs in cell-arsenic (As) interactions has not been reported in microorganisms and thus we explored this interaction using Synechocystis PCC 6803 as a model system. The effect of half maximal inhibitory concentration (IC50) [~300 mM As (V) and ~4 mM As (III)] and non-inhibitory [4X lower than IC50, i.e., 75 mM As (V) and 1 mM As (III)] of As was studied on Synechocystis cells in relation to its effect on Chlorophyll (Chl) a, type IV pili (TFP)-As interaction and intracellular/extracellular presence of As. In silico analysis showed that subunit PilA1 of electrically conductive TFP, i.e., microbial nanowires of Synechocystis have putative binding sites for As. In agreement with in silico analysis, transmission electron microscopy analysis showed that As was deposited on Synechocystis nanowires at all tested concentrations. The potential of Synechocystis nanowires to immobilize As can be further enhanced and evaluated on a large scale and thus can be applied for bioremediation studies.

Cadaveric feasibility study on the use of ultrasound contrast to assess spread of injectate in the serratus anterior muscle plane

BACKGROUND

The Serratus anterior muscle plane (SAP) block has recently been described for the purpose of perioperative pain management following cases of trauma and breast surgery. It might prove a safer alternative to the other regional thoracic paravertebral and central neuraxial blockade techniques. There are no descriptive cadaveric studies in the pre-existing literature to delineate the anatomical plane for this novel technique. The main objectives for our study were to examine the location of the Serratus anterior muscle belly, assess the efficacy of achieving adequate delineation of the muscle plane utilising ultrasound imaging with agitated water as the contrast agent, and finally, to observe the extent of the cepahlo-caudal spread of the injectate in the SAP.

MATERIALS AND METHODS

Seven cadavers were studied. 20 mls of saline was injected into posterior axillary line (PAL) at the level of the 4-5(th) rib under ultrasound guidance. This was followed by injection of 10 mls of water with air (8 mls water and 2 mls of air). The presence of hyperechoic air bubbles in the fluid distended SAP (hypoechoic) area demonstrated the spread of water and air.

RESULTS

In 36% of cadavers, fully formed Serratus Anterior muscle belly was identified at the midaxillary line (MAL), 14% in PAL, and remaining 50% between PAL and MAL. The lower most limit of air-water spread was identified at the subcostal margin. Cephalad spread of contrast was noted in 2(nd) intercostal space ICS (7%), 3(rd) ICS (71%), and 4(th) ICS (22%).

CONCLUSION

This study describes that the serratus anterior muscle is well-formed near the PAL and the injectate spread can be determined with the help of agitated water contrast on ultrasound. Furthermore, there was variability in the cephalad spread of the injectate.

Identification and topographical characterisation of microbial nanowires in Nostoc punctiforme

Extracellular pili-like structures (PLS) produced by cyanobacteria have been poorly explored. We have done detailed topographical and electrical characterisation of PLS in Nostoc punctiforme PCC 73120 using transmission electron microscopy (TEM) and conductive atomic force microscopy (CAFM). TEM analysis showed that N. punctiforme produces two separate types of PLS differing in their length and diameter. The first type of PLS are 6-7.5 nm in diameter and 0.5-2 µm in length (short/thin PLS) while the second type of PLS are ~20-40 nm in diameter and more than 10 µm long (long/thick PLS). This is the first study to report long/thick PLS in N. punctiforme. Electrical characterisation of these two different PLS by CAFM showed that both are electrically conductive and can act as microbial nanowires. This is the first report to show two distinct PLS and also identifies microbial nanowires in N. punctiforme. This study paves the way for more detailed investigation of N. punctiforme nanowires and their potential role in cell physiology and symbiosis with plants.

Inquisition of Microcystis aeruginosa and Synechocystis nanowires: characterization and modelling

Identification of extracellular conductive pilus-like structures (PLS) i.e. microbial nanowires has spurred great interest among scientists due to their potential applications in the fields of biogeochemistry, bioelectronics, bioremediation etc. Using conductive atomic force microscopy, we identified microbial nanowires in Microcystis aeruginosa PCC 7806 which is an aerobic, photosynthetic microorganism. We also confirmed the earlier finding that Synechocystis sp. PCC 6803 produces microbial nanowires. In contrast to the use of highly instrumented continuous flow reactors for Synechocystis reported earlier, we identified simple and optimum culture conditions which allow increased production of nanowires in both test cyanobacteria. Production of these nanowires in Synechocystis and Microcystis were found to be sensitive to the availability of carbon source and light intensity. These structures seem to be proteinaceous in nature and their diameter was found to be 4.5-7 and 8.5-11 nm in Synechocystis and M. aeruginosa, respectively. Characterization of Synechocystis nanowires by transmission electron microscopy and biochemical techniques confirmed that they are type IV pili (TFP) while nanowires in M. aeruginosa were found to be similar to an unnamed protein (GenBank : CAO90693.1). Modelling studies of the Synechocystis TFP subunit i.e. PilA1 indicated that strategically placed aromatic amino acids may be involved in electron transfer through these nanowires. This study identifies PLS from Microcystis which can act as nanowires and supports the earlier hypothesis that microbial nanowires are widespread in nature and play diverse roles.

Sendai virus is a safe and immunogenic Jennerian vaccine for human parainfluenza virus-type 1 in 3-6 year old children (VAC8P.1053)

Human parainfluenza viruses are responsible for tens of thousands of hospitalizations and hundreds of thousands of emergency room visits each year in the United States. Included in this group of viruses is human parainfluenza virus-type 1 (hPIV-1), the main causative agent of laryngotracheobronchitis (croup) in young children, for which there is currently no licensed vaccine. In response to this need, we have developed a Jennerian vaccine that employs the use of murine PIV-1 (Sendai virus, SeV) to produce cross-reactive antibodies towards hPIV-1. The vaccine was administered as a single intranasal dose to healthy, hPIV-1 seropositive, 3-6 year old children in a dose escalation study (5 x 105, 5 x 106 or 5 x 107 EID50). Importantly, the vaccine was well tolerated by all participants. No replication of the viral vaccine was detected in the airway of any participant. Within four weeks of vaccination, most participants showed an increase in binding and neutralizing antibodies towards hPIV-1. For several participants, antibody responses remained elevated at six months post-vaccination. The results of this study suggest that hPIV-1 vaccination may be beneficial to boost immunity in seropositive children, and encourage testing of the vaccine in young, seronegative children who are most at risk for respiratory virus disease.

Prospective evaluation for respiratory pathogens in children with sickle cell disease and acute respiratory illness

BACKGROUND

Human rhinovirus (HRV), human coronavirus (hCoV), human bocavirus (hBoV), and human metapneumovirus (hMPV) infections in children with sickle cell disease have not been well studied.

PROCEDURE

Nasopharyngeal wash specimens were prospectively collected from 60 children with sickle cell disease and acute respiratory illness, over a 1-year period. Samples were tested with multiplexed-PCR, using an automated system for nine respiratory viruses, Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Bordetella pertussis. Clinical characteristics and distribution of respiratory viruses in patients with and without acute chest syndrome (ACS) were evaluated.

RESULTS

A respiratory virus was detected in 47 (78%) patients. Nine (15%) patients had ACS; a respiratory virus was detected in all of them. The demographic characteristics of patients with and without ACS were similar. HRV was the most common virus, detected in 29 of 47 (62%) patients. Logistic regression showed no association between ACS and detection of HRV, hCoV, hBoV, hMPV, and other respiratory pathogens. Co-infection with at least one additional respiratory virus was seen in 14 (30%) infected patients, and was not significantly higher in patients with ACS (P = 0.10). Co-infections with more than two respiratory viruses were seen in seven patients, all in patients without ACS. Bacterial pathogens were not detected.

CONCLUSION

HRV was the most common virus detected in children with sickle cell disease and acute respiratory illness, and was not associated with increased morbidity. Larger prospective studies with asymptomatic controls are needed to study the association of these emerging respiratory viruses with ACS in children with sickle cell disease.

Gitelman's syndrome: Rare presentation with growth retardation

Gitelman's syndrome is an autosomal recessive disorder characterized by hypokalemic metabolic alkalosis, hypokalemia, hypomagnesaemia, hypocalciuria, hyperreninemia and without hypertension. Gitelman's syndrome is caused by mutations of the SLC12A3 gene, which encodes the Na/Cl co-transporter (NCCT) in the distal convoluted tubule. Majority of cases manifest during adolescence or adulthood and growth retardation is not the common feature. We report a rare presentation of Gitelman's syndrome in a four-year-old boy with growth retardation.

Application of WHONET in the Antimicrobial Resistance Surveillance of Uropathogens: A First User Experience from Nepal

INTRODUCTION

WHONET is a freely downloadable, Windows-based database software which is used for the management and analysis of microbiology data, with a special focus on the analysis of antimicrobial susceptibility test results. Urinary Tract Infections (UTI) are a common medical problem and they are responsible for notable morbidity among young and sexually active women.

OBJECTIVES

The major objective of this study was the utilization and application of the WHONET program for the Antimicrobial Resistance (AMR) surveillance of uropathogens.

METHODS

A total of 3209 urine samples were collected from patients who visited Manipal Teaching Hospital with a clinical suspicion of UTI, during December 2010 to July 2011. The isolation and characterization of the isolates were done by conventional methods. Antimicrobial Susceptibility Testing (AST) was performed by Kirby Bauer's disc diffusion method. The data entry and analysis were done by using the WHONET 5.6 software.

RESULTS

Out of the 3209 specimens, 497 bacterial isolates were obtained and they were subjected to AST. Escherichia coli (66.2%) was the commonest bacterial isolate, followed by Enterococcus species (9.3%), Staphylococcus aureus (5.0%), and Klebsiella pneumoniae (4.2%). Among the gram-negative enteric bacilli, a high prevalence of resistance was observed against ampicillin and ciprofloxacin. The gram negative nonfermenters exhibited a high degree of resistance to ceftazidime. Staphylococcus species. showed a moderately high resistance to co-trimoxazole. One isolate was Vancomycin Resistant Enterococci (VRE).

CONCLUSION

This study, a first of its kind which was done in Nepal, was carried out by using the WHONET software to monitor, analyze and share the antimicrobial susceptibility data at various levels. This study was also aimed at building a surveillance network in Nepal, with the National Public Health Laboratory, Nepal, acting as a nodal centre. This would help in the formulation of antibiotic policies and in identifying hospital and community outbreaks at the nodal centre, as well as in sharing information with the clinicians at the local level.

Guideline for the management of fever and neutropenia in children with cancer and/or undergoing hematopoietic stem-cell transplantation

PURPOSE

To develop an evidence-based guideline for the empiric management of pediatric fever and neutropenia (FN).

METHODS

The International Pediatric Fever and Neutropenia Guideline Panel is a multidisciplinary and multinational group composed of experts in pediatric oncology and infectious disease as well as a patient advocate. The Panel was convened for the purpose of creating this guideline. We followed previously validated procedures for creating evidence-based guidelines. Working groups focused on initial presentation, ongoing management, and empiric antifungal therapy. Each working group developed key clinical questions, conducted systematic reviews of the published literature, and compiled evidence summaries. The Grades of Recommendation Assessment, Development, and Evaluation approach was used to generate summaries, and evidence was classified as high, moderate, low, or very low based on methodologic considerations.

RESULTS

Recommendations were made related to initial presentation (risk stratification, initial evaluation, and treatment), ongoing management (modification and cessation of empiric antibiotics), and empiric antifungal treatment (risk stratification, evaluation, and treatment) of pediatric FN. For each recommendation, the strength of the recommendation and level of evidence are presented.

CONCLUSION

This guideline represents an evidence-based approach to FN specific to children with cancer. Although some recommendations are similar to adult-based guidelines, there are key distinctions in multiple areas. Implementation will require adaptation to the local context.

Observation on integron carriage among clinical isolates of Klebsiella pneumoniae producing extended-spectrum beta-lactamases

PURPOSE

Klebsiella pneumoniae is considered an important pathogen causing nosocomial and community-acquired infections and is often associated with the production of extended-spectrum beta-lactamases (ESBL) belonging to SHV and CTX-M families, which are frequently described as a part of complex integrons, facilitate their horizontal transfer to other related as well as unrelated microbes. The present study was undertaken to investigate the occurrence and characterization of integrons among K pneumoniae isolates producing ESBL in a tertiary referral hospital.

MATERIALS AND METHODS

A total of 136 clinical isolates of K pneumoniae were investigated for the presence of ESBL. Their ESBL genes were characterized by multiplex polymerase chain reaction (PCR). Integrase gene PCR was performed to detect the presence of integron. The isolates were further typed by random amplification of polymorphic DNA (RAPD).

RESULT

Out of 136 K pneumoniae isolates, 63 (46%) were confirmed to be ESBL producers. SHV (68%) and CTX-M (67%) ESBL genes were the most common in our study. Of the 63 ESBL-positive isolates, 58 (92%) strains carried integrons; 52 strains (82%) carried only class 1 integron, whereas 6 (9%) isolates harboured both class 2 integrons and the class 1 gene. However, in ESBL negatives, only 29 (40%) strains were positive for class 1 integron and none for class 2 integron.

CONCLUSION

The presence of class 2 integron amongst ESBL-producing K pneumoniae is being described for the first time in this part of the world. The findings of this study strongly suggest that integrons have a role in the dissemination of ESBL-mediated resistance among the nosocomial isolates of K pneumonia.

Role of Prophylactic Antibiotics in Laparoscopic Cholecystectomy

BACKGROUND

Antibiotic prophylaxis is routinely administered in laparoscopic cholecystetomy but its role is debatable.

METHODS

From January 2004 to August 2008, 417 patients were randomized into 208 in antibiotic group (AG) and 209 in non antibiotic group (NAG). AG received one dose each of injection ciprofloxacin (200 mg) and metronidazole (500mg) preoperatively. NAG was given only intravenous fluids. Besides routine care, all underwent abdominal sonography and liver function tests at least once during the 30 postoperative days.

RESULT

Age, sex and co-morbidity distribution were similar in both the groups. One patient who was on weekly 5mg methotraxate (NAG) had erythema around umbilical port. Other three having umbilical discharge recovered without antibiotics. Nine patients had subhepatic collection (5 AG and 4 NAG). One from NAG underwent re-laparoscopy and drainage. Ten patients had fever. Two from AG had basal lung collapse and were given antibiotics.

CONCLUSION

Antibiotic prophylaxis is not needed for laparoscopic cholecystectomy.

Increased prevalence of extended spectrum beta lactamase producers in neonatal septicaemic cases at a tertiary referral hospital

Emergence of extended spectrum beta lactamases (ESBLs) producing strains of gram negative bacteria, as one of the leading cause of septicaemia often complicates the clinical and therapeutic outcome. The present study was undertaken to investigate the prevalence of ESBLs in bacteria isolated from neonatal septicaemic cases along with their antimicrobial sensitivity pattern. Blood samples were collected from 243 suspected cases of neonatal septicaemia. Apart from susceptibility testing, all the gram negative isolates were subjected to phenotypic tests for ESBL production. Amongst the positive test samples (n = 115), 84 were gram negative rods. ESBL was detected in 26 (32%) isolates. Results indicate that routine ESBL detection should be made imperative and empirical use of third generation cephalosporins must be discouraged.

Safety and immunogenicity of recombinant poxvirus HIV-1 vaccines in young adults on highly active antiretroviral therapy

A trial to evaluate the safety and immunogenicity of recombinant modified vaccinia Ankara (MVA) and fowlpox (FP) vectors expressing multiple HIV-1 proteins was conducted in twenty HIV-1 infected youth with suppressed viral replication on HAART. The MVA and FP-based multigene HIV-1 vaccines were safe and well tolerated. Increased frequencies of HIV-1 specific CD4+ proliferative responses and cytokine secreting cells were detected following immunization. Increased frequencies and breadth of HIV-1 specific CD8 T-cell responses were also detected. Plasma HIV-1-specific antibody levels and neutralizing activity were unchanged following vaccination. Poxvirus-based vaccines may merit further study in therapeutic vaccine protocols.

Observations on carbapenem resistance by minimum inhibitory concentration in nosocomial isolates of Acinetobacter species: an experience at a tertiary care hospital in North India

Acinetobacter species are emerging as an important nosocomial pathogen. Multidrug-resistant Acinetobacter spp. has limited the option for effective treatment. Although carbapenems are effective for the treatment of such infections, resistance to this drug has recently been reported. This study was undertaken to assess resistance to carbapenem in clinical isolates of Acinetobacter spp. from hospitalized patients by both disc-diffusion and minimum inhibitory concentration (MIC) methods. All clinical samples from suspected cases of nosocomial infections were processed, and 265 isolates were identified as Acinetobacter species. These isolates were tested for antibiotic resistance by the disc-diffusion method with 14 antimicrobials, including meropenem and imipenem. Thereafter, all Acinetobacter species were subjected to MIC for meropenem. More than 80% resistance to second- and third-generation cephalosporins, aminoglycosides, and quinolones was recorded. Thirty percent of the strains were resistant to cefoperazone/sulbactam. Resistance to meropenem was observed in 6.4% of Acinetobacter spp. while 8.3% of the isolates showed intermediate resistance detected by MIC. All carbapenem-resistant/intermediate strains were also resistant to other (>10) antibiotics tested by the disc-diffusion method. The rising trend of resistance to carbapenem poses an alarming threat to the treatment for such infections. Regular monitoring, judicious prescription, and early detection of resistance to carbapenem are necessary to check further dissemination of drug resistance in Acinetobacter spp.

Legionella bozemanii pulmonary abscess in a pediatric allogeneic stem cell transplant recipient

Legionella spp. infections are often considered in the differential diagnosis of pneumonia in adults. This case report describes a pediatric stem cell transplant recipient presenting with cavitary pulmonary disease secondary to Legionella bozemanii infection. Also highlighted with this atypical clinical presentation are challenges in diagnosing legionellosis and concerns of increased vulnerability for such infections when severely immunocompromised patients are changed to nontrimethoprim-sulfamethoxazole Pneumocystis jiroveci pneumonia prophylaxis.