Monday, 25 December 2017

Yersinia enterocolitica: Diarrhoea causative agent

Yersinia enterocolitica is a Gram negative rod-shaped bacterium in the family of Enterobacteriaceae known as causative agent of gastrointestinal infections and most often causes the disease yersiniosis with a variety of symptoms such as enterocolitis, acute diarrhea, terminal ileitis and pseudoappendicitis but, if it spreads systemically, can also result in fatal sepsis. The genus Yersinia includes 11 species: Y. pestis, Y. pseudotuberculosis, Y. enterocolitica, Y. frederiksenii, Y. intermedia, Y. kristensenii, Y. bercovieri, Y. mollaretii, Y. rohdei, Y. aldovae, and Y. ruckeri. Among them, only Y. pestis, Y. pseudotuberculosis, and certain strains of Y. enterocolitica are of pathogenic importance for humans and certain warm-blooded animals, whereas the other species are of environmental origin and may, at best, act as opportunists. However, Yersinia strains can be isolated from clinical materials, so have to be identified at the species level.
Signs and symptoms
Symptoms of Y. enterocolitica infection typically include Diarrhea which is the most common clinical manifestation of this infection; diarrhea may be bloody in severe cases, low grade fever, abdominal pain, vomiting. The patient may also develop erythema nodosum, which manifests as painful, raised red or purple lesions, mainly on the patient’s legs and trunk. Lesions appear 2-20 days after the onset of fever and abdominal pain and resolve spontaneously in most cases in about a month.
Y. enterocolitica infection can be diagnosis by a number of methods which includes Stool culture - This is the best way to confirm a diagnosis of Y. enterocolitica. The figure above shows the growth of Y. enterocolitica on CIN (Cefsulodin, Irgasan, Novobiocin) Agar. The characteristic deep red center with a transparent margin, or "bull's-eye" appearance of Yersinia andAeromonas colonies is important for identification, and is due to the presence of mannitol. Y. enterocolitica ferments the mannitol in the medium, producing an acid pH which gives the colonies their red color and the "bull's eye" appearance. Sodium deoxycholate, cefsulodin, irgasan, and novobiocin are added as selective agents. Altorfer found that by reducing the concentration of cefsulodin from 15.0 to 4.0mcg/ml, CIN Agar could also be used to selectively isolate Aeromonas spp., in addition to Yersinia.
Other diagnosis methods include tube agglutination, Enzyme-linked immunosorbent assays
Radioimmunoassays, Imaging studies - Ultrasonography or computed tomography (CT) scanning may be useful in delineating true appendicitis from pseudoappendicitis, Colonoscopy - Findings may vary and are relatively nonspecific, Joint aspiration in cases of Yersinia- associated reactive arthropathy
Care in patients with Y enterocolitica infection is primarily supportive, with good nutrition and hydration being mainstays of treatment
First-line drugs used against the bacterium include the following agents:
Third-generation cephalosporins
Trimethoprim-sulfamethoxazole (TMP-SMZ)
Fluoroquinolones - not approved for use in children under 18 years

Sunday, 27 August 2017

Global Shortage of Hepatitis B Vaccine - PHE

Image result for hepatitis b vaccine
There is currently a global shortage of hepatitis B vaccine which has been caused by problems in the manufacturing process.
Public Health England, working with NHS England, the Department of Health and the manufacturers, have put in place a series of measures so that the NHS and other providers can use the available vaccine for those at highest immediate risk. Measures are expected to continue until the beginning of 2018 and will be kept under review.
The risk of catching hepatitis B infection in the UK is very low.
In the UK, vaccination is usually offered to individuals who are at specific risk of being exposed to blood from an infected person. This includes babies born to mothers who are infected with hepatitis B, the sexual partners of infected individuals and a range of other groups such as men who have sex with men, healthcare workers, and people who inject drugs. Vaccination is also recommended for people who will be undertaking certain activities overseas.
A course of hepatitis B vaccine usually involves 3 doses of vaccine, completed over a few months. While supplies are limited, vaccine will be prioritised for those at highest immediate risk based on their doctor’s assessment. For other people, a doctor may advise that hepatitis B vaccine can be deferred until later.
Hepatitis B virus is found in the blood and bodily fluids, such as semen and vaginal fluids, of an infected person. It cannot be spread by kissing, holding hands, hugging, coughing, sneezing, or sharing crockery and utensils.
Individuals can reduce their risk of contracting hepatitis B by taking care to:
·         avoid having unprotected sex
·         not inject drugs, or by not sharing needles when injecting
·         avoid having tattoos, piercing or acupuncture when overseas
·         avoid accessing medical or dental care in high prevalence countries
Vaccination will still be available, as now, for those who have already been exposed to hepatitis B. Such people should seek urgent medical attention as the infection can still be prevented if treated promptly after the incident.
The recently announced addition of hepatitis B protection to the routine childhood immunisation programme at 2, 3 and 4 months will go ahead. The combined vaccine, which protects against hepatitis B and 5 other diseases, is not affected by this shortage.

Long term hepatitis B infection can be symptomless and people who think they may have acquired the infection in the past should seek a test from their healthcare professional.


Sunday, 15 January 2017

Killer Superbug: Pan-Resistant New Delhi Metallo-Beta-Lactamase-Producing Klebsiella pneumoniae

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On August 25, 2016, the Washoe County Health District in Reno, Nevada, was notified of a patient at an acute care hospital with carbapenem-resistant Enterobacteriaceae (CRE) that was resistant to all available antimicrobial drugs. The specific CRE, Klebsiella pneumoniae, was isolated from a wound specimen collected on August 19, 2016. After CRE was identified, the patient was placed in a single room under contact precautions. The patient had a history of recent hospitalization outside the United States. Therefore, based on CDC guidance, the isolate was sent to CDC for testing to determine the mechanism of antimicrobial resistance, which confirmed the presence of New Delhi metallo-beta-lactamase (NDM).
The patient was a female Washoe County resident in her 70s who arrived in the United States in early August 2016 after an extended visit to India. She was admitted to the acute care hospital on August 18 with a primary diagnosis of systemic inflammatory response syndrome, likely resulting from an infected right hip seroma. The patient developed septic shock and died in early September. During the 2 years preceding this U.S. hospitalization, the patient had multiple hospitalizations in India related to a right femur fracture and subsequent osteomyelitis of the right femur and hip; the most recent hospitalization in India had been in June 2016.
Antimicrobial susceptibility testing in the United States indicated that the isolate was resistant to 26 antibiotics, including all aminoglycosides and polymyxins tested, and intermediately resistant to tigecycline (a tetracycline derivative developed in response to emerging antibiotic resistance). Because of a high minimum inhibitory concentration (MIC) to colistin, the isolate was tested at CDC for the mcr-1 gene, which confers plasma-mediated resistance to colistin; the results were negative. The isolate had a relatively low fosfomycin MIC of 16 μg/mL by ETEST. However, fosfomycin is approved in the United States only as an oral treatment of uncomplicated cystitis; an intravenous formulation is available in other countries.
A point prevalence survey, using rectal swab specimens and conducted among patients currently admitted to the same unit as the patient, did not identify additional CRE. Active surveillance for multidrug-resistant bacilli including CRE has been conducted in Washoe County since 2010 and is ongoing; no additional NDM CRE have been identified.

The BBC Health described that the analysis found the superbug was resistant to all 26 available antibiotics in the US including the "drug of last resort" - colistin.