Archive for January 12, 2014

Colistin: re-emergence of the ‘forgotten’ antimicrobial agent.

J Postgrad Med. 2013 Jul-Sep;59(3):208-15.

Dhariwal AK, Tullu MS.


The treatment of the emerging multidrug resistant (MDR) gram-negative organisms is a challenge. The development of newer antibiotics has recently slowed down. This has led to the re-emergence of the ‘old forgotten’ antibiotic “Colistin”, whose use had almost stopped (after 1970’s) due to the high incidence of nephrotoxicity and neurotoxicity.

Colistin (polymyxin E) is a polypeptide antibiotic belonging to polymyxin group of antibiotics with activity mainly against the gram-negative organisms. Use of colistin has been increasing in the recent past and newer studies have shown lesser toxicity and good efficacy.

Colistin acts on the bacterial cell membrane resulting in increased cell permeability and cell lysis. Colistin can be administered orally, topically, by inhalational route, intramuscularly, intrathecally, and also intravenously.

Parenteral Colistin (in the form of colistimethate sodium) has been used to treat ventilator-associated pneumonia (VAP) and bacteremia caused by MDR bacteria such as Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii.

Inhaled Colistin is used for treating pneumonia/VAP due to MDR gram-negative organisms and also used prophylactically in patients with cystic fibrosis.

This manuscript is a brief review of Colistin and its clinical applications in the pediatric population.

FULL TEXT;year=2013;volume=59;issue=3;spage=208;epage=215;aulast=Dhariwal

January 12, 2014 at 7:15 pm

Venezuelan Equine Encephalitis Viruses (VEEV) in Argentina: Serological Evidence of Human Infection.

PLoS Negl Trop Dis. 2013 Dec 12;7(12):e2551.

Pisano MB1, Oria G2, Beskow G2, Aguilar J1, Konigheim B1, Cacace ML3, Aguirre L4, Stein M2, Contigiani MS1.


Venezuelan equine encephalitis viruses (VEEV) are responsible for human diseases in the Americas, producing severe or mild illness with symptoms indistinguishable from dengue and other arboviral diseases. For this reason, many cases remain without certain diagnosis.

Seroprevalence studies for VEEV subtypes IAB, ID, IF (Mosso das Pedras virus; MDPV), IV (Pixuna virus; PIXV) and VI (Rio Negro virus; RNV) were conducted in persons from Northern provinces of Argentina: Salta, Chaco and Corrientes, using plaque reduction neutralization test (PRNT). RNV was detected in all studied provinces.

Chaco presented the highest prevalence of this virus (14.1%). Antibodies against VEEV IAB and -for the first time- against MDPV and PIXV were also detected in Chaco province.

In Corrientes, seroprevalence against RNV was 1.3% in the pediatric population, indicating recent infections. In Salta, this was the first investigation of VEEV members, and antibodies against RNV and PIXV were detected.

These results provide evidence of circulation of many VEE viruses in Northern Argentina, showing that surveillance of these infectious agents should be intensified.


January 12, 2014 at 7:14 pm

Corticosteroids for dengue – why don’t they work?

PLoS Negl Trop Dis. 2013 Dec 12;7(12):e2592.

Nguyen TH1, Nguyen TH1, Vu TT1, Farrar J2, Hoang TL3, Dong TH4, Ngoc Tran V4, Phung KL1, Wolbers M2, Whitehead SS5, Hibberd ML3, Wills B2, Simmons CP6.



Dysregulated immune responses may contribute to the clinical complications that occur in some patients with dengue.


In Vietnamese pediatric dengue cases randomized to early prednisolone therapy, 81 gene-transcripts (0.2% of the 47,231 evaluated) were differentially abundant in whole-blood between high-dose (2 mg/kg) prednisolone and placebo-treated patients two days after commencing therapy. Prominent among the 81 transcripts were those associated with T and NK cell cytolytic functions. Additionally, prednisolone therapy was not associated with changes in plasma cytokine levels.


The inability of prednisolone treatment to markedly attenuate the host immune response is instructive for planning future therapeutic strategies for dengue.


January 12, 2014 at 7:11 pm

Is There a Risk of Yellow Fever Virus Transmission in South Asian Countries with Hyperendemic Dengue?

Biomed Res Int. 2013;2013:905043.

Agampodi SB1, Wickramage K2.


The fact that yellow fever (YF) has never occurred in Asia remains an “unsolved mystery” in global health. Most countries in Asia with high Aedes aegypti mosquito density are considered “receptive” for YF transmission. Recently, health officials in Sri Lanka issued a public health alert on the potential spread of YF from a migrant group from West Africa.

We performed an extensive review of literature pertaining to the risk of YF in Sri Lanka/South Asian region to understand the probability of actual risk and assist health authorities to form evidence informed public health policies/practices.

Published data from epidemiological, historical, biological, molecular, and mathematical models were harnessed to assess the risk of YF in Asia. Using this data we examine a number of theories proposed to explain lack of YF in Asia. Considering the evidence available, we conclude that the probable risk of local transmission of YF is extremely low in Sri Lanka and for other South Asian countries despite a high Aedes aegypti density and associated dengue burden.

This does not however exclude the future possibility of transmission in Asia, especially considering the rapid influx travelers from endemic areas, as we report, arriving in Sri Lanka.


January 12, 2014 at 7:10 pm

Acute pyogenic discitis in a degenerative intervertebral disc in an adult.

Int Med Case Rep J. 2010 Aug 4;3:77-80. Print 2010.

Tanaka M, Shimizu H, Yato Y, Asazuma T, Nemoto K.


A 35-year-old male who had been receiving conservative treatment for L4 isthmic spondylolisthesis suffered from pyogenic spondylodiscitis in the degenerative L4/L5 intervertebral disc space, which could be identified by comparison with previous images. Symptoms improved with conservative antibiotic treatment. Neovascularization may occur in the annulus fibrosus of a degenerative intervertebral disc, which may increase the risk of hematogenous infection, leading to “discitis” even in adults.


January 12, 2014 at 7:07 pm

Surgical treatment of spondylodiscitis. An update.

Int Orthop. 2012 Feb;36(2):413-20.

Guerado E, Cerván AM.



Spondylodiscitis refers to an infection affecting the intervertebral disk, the vertebral body or the posterior arch of the vertebra being aetiologically, pyogenic, granulomatous (tuberculosis, brucellosis, or fungal infection) or parasitic.


Spondylodiscitis diagnosis is based on clinical symptoms, a combination of erythrocyte sedimentation rate with C-reactive protein (CRP) tests and, less useful, leukocytosis. Blood culture is also a very cost-effective method of identifying organisms. Plain radiographs are useful, however changes may take several months to appear. Radionuclide tests are currently less used; nevertheless, fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) shows encouraging results particularly when magnetic resonance images (MRI) are unconvincing in the distinction between degenerative changes and infection. MRI with gadolinium enhancement is the choice for image diagnosis.


Medical management is usually the basis for treatment, alone or in combination with surgery. Surgical approach, either by endoscopy or open, is indicated for biopsy when clinical evolution is unsatisfactory and no micro-organism has been isolated, and also whenever a root, spinal cord or dural compression is seen on MRI; spinal instability or severe deformity are also clear indications for surgical treatment. Less invasive surgery either CT-scan guided or, particularly, by endoscopy has good results. However open surgery is still the standard. The anterior approach allows for anterior disc and bone debridement. The posterior approach is indicated when posterior elements are involved or in the presence of an epidural abscess. Although good results have been claimed, the use of instrumentation in the presence of an infected focus is controversial, as the use of cages or BMPs are.



January 12, 2014 at 10:29 am

Management of infectious discitis. Outcome in one hundred and eight patients in a university hospital.

Int Orthop. 2012 Feb;36(2):239-44.

Cebrián Parra JL, Saez-Arenillas Martín A, Urda Martínez-Aedo AL, Soler Ivañez I, Agreda E, Lopez-Duran Stern L.



The optimal management of pyogenic discitis is not agreed on. We conducted a retrospective, cross-sectional, observational study in which all patients with discitis who attended Hospital San Carlos Madrid from January 1999 to January 2009 were included.


We identified 108 consecutive adult patients with infectious discitis. There were 49 men and 59 women with an average age of 67,5 (+/- 16,89) years in the study group. Mean follow-up interval was 6,06 (12,5-2) years. 78 patients had spontaneous discitis and 30 patients had postoperative discitis. Inclusion criteria for the review were illness compatible with vertebral infection and / or evidence of spinal involvement on magnetic resonance imaging (MRI).


In 56 percutaneous discal biopsy (52% patients) were positive in 28 cases. A single disc was infected in 100 patients. The segments involved were the cervical spine in four, the thoracic spine in 38 and the lumbar spine in 66. One or more comorbid diseases were present in 73 (68%) of 108 patients. Diabetes mellitus was the most common disease. Comorbid disease was rapidly fatal in four patients, ultimately fatal in seven patients, and nonfatal or not present in 97 patients (90 %).


Early diagnosis is a major challenge. Heightened awareness and the prompt use of MRI are necessary to avoid diagnostic delay. Prolonged antimicrobial therapy and the judicious application of timely surgical intervention are essential for an optimal outcome.


January 12, 2014 at 10:27 am

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