News Scan for Aug 09, 2017

New gonorrhea antibiotic
MERS clinical picture
Plant-based Zika vaccine
H9N2 in China

New antibiotic shows promise against gonorrhea in lab experiments

New early-stage research out of the United Kingdom has identified a potential antibiotic candidate for treatment of drug-resistant gonorrhea.

In a paper published in Antimicrobial Agents and Chemotherapy, scientists from the London School of Hygiene and Tropical Medicine and Imperial College London report that the novel antimicrobial closthioamide (CTA) inhibited the growth of 146 of 149 (98%) clinical Neisseria gonorrhea isolates at a minimum inhibitory concentration of 0.125mg/L or less, a low therapeutic dose that could reduce any potential toxicity. Furthermore, the in vitro tests showed CTA to be effective against N gonorrhea isolates that were resistant to ciprofloxacin and to the first-line antibiotics ceftriaxone and azithromycin.

CTA, discovered in 2010, is derived from the anaerobic bacterium Clostridium cellulolyticum. It has been shown to have high in vitro activity against other drug-resistant microorganisms, including multidrug-resistant (MDR) bacteria.

The emergence of gonorrhea strains that are resistant to azithromycin and ceftriaxone—the currently recommended treatments for the sexually transmitted infection—is a major concern for public health officials, since there are no other alternatives. Last month, the World Health Organization warned that widespread treatment failure is likely in the coming years unless new antibiotics are developed. Serious and permanent health problems, including pelvic inflammatory disease and infertility, can result if gonorrhea goes untreated.

The authors of the study say that while the initial laboratory results are intriguing, further research in animals and humans is needed to evaluate CTA's safety and effectiveness.

"Despite showing tremendous promise, it will be a number of years before, and if, we can use the drug in real life human cases," lead author John Heap, PhD, said in a news release from Imperial College London.
Aug 7 Antimicrob Agents Chemother abstract
Aug 7 Imperial College London news release


Symptom overlap makes MERS tests crucial for differential diagnosis

Patients critically ill with MERS-CoV infections have symptoms and risk factors similar to those of people severely ill with other types of respiratory infections, a research team from Saudi Arabia recently reported in an early online edition of Critical Care Medicine. The study is the largest to date to compare critically sick Middle East respiratory syndrome coronavirus (MERS-CoV) patients with a large cohort of patients similarly ill from a variety of different causes.

For their analysis, the authors looked at patients admitted to intensive care units (ICUs) at 14 hospitals in Saudi Arabia. They compared clinical information from 330 patients who had lab-confirmed MERS-CoV infections between Sep 2012 and Oct 2015 with data from 222 people who were critically ill with other types of community-acquired respiratory infections.

Though patients who were sick with MERS-CoV tended to be younger, their clinical pictures and underlying health conditions overlapped substantially with people had other types of severe respiratory infections. Those with MERS-CoV had severe hypoxemic respiratory failure and experienced nonrespiratory organ failure more often, which prompted more frequent mechanical ventilation, extracorporeal membrane oxygenation (ECMO), vasopressor support, and renal replacement therapy.

The researchers also found that initial negative results on reverse transcription polymerase chain reaction (RT-PCR) testing does not rule out MERS-CoV; the initial test was positive in only 76.2% of patients who were ultimately diagnosed with the infection, and specimens from the upper respiratory tract were more likely to initially test negative.

After adjusting for confounding factors, the clinicians found that MERS-CoV illness was independently associated with death—a five- to six-fold increase—compared with other types of severe respiratory infections.

Though they found key differences in clinical findings and outcomes between the two groups of patients, given the overlap in findings, a high index of suspicion and timely diagnostic testing are essential for investigating severe respiratory infections in at-risk patients, the team concluded. "This overlap has important implications for practice, as a MERS diagnosis based on clinical, radiologic, and standard laboratory data alone is not possible," they wrote.
Aug 3 Crit Care Med abstract


First plant-based Zika vaccine developed

Arizona State University (ASU) researchers have developed a new Zika vaccine candidate using tobacco plants. The first plant-based Zika vaccine has the potential to be both low-cost and easily reproduced, the researchers write in a study published in Scientific Reports.

The vaccine uses a virus like particle (VLP) carrier based on the hepatitis B core antigen that displays part of the Zika virus envelope protein. It can be produced quickly in large quantities in tobacco plant leaves, according to the study authors. Challenge studies in mice that had received two doses prompted antibody and cellular immune responses that provided 100% protection against multiple Zika strains.

Unlike other Zika vaccine candidates, the researchers said the plant-based VLP reduces the risk of antibody dependent enhancement, a factor if the recipient of the vaccine contracts dengue or another flavivirus. The study was partly supported by the National Institute of Allergy and Infectious Diseases.

"Our study has provided the proof-of-principle and feasibility necessary for the further development of more potent, affordable, and potentially safer recombinant protein-based subunit vaccines against the worldwide ZIKV epidemic," the authors concluded.
Aug 9 Scientific Reports study
Aug 9 ASU press release


Baby from China infected with H9N2

A 2-month-old baby from Guangdong province is the third person infected with H9N2 avian influenza in China this year. Details of the patient's case were published in the World Health Organization's (WHO's) latest update on influenza at the human-animal interface.

China reported the H9N2 avian influenza case to the WHO on Jun 30. The baby began having symptoms on Apr 28 and was hospitalized on Jun 9. She tested positive for H9N2 on Jun 16, and has since made a full recovery. The patient was exposed to backyard poultry before she became sick. H9N2 is endemic in Chinese poultry.

H9N2 infections are more common in children than in adults. This year's previous cases involved an 11-month-old boy from Gansu province whose illness was reported in February and a 32-year-old man from Beijing whose infection was detected in May.
Aug 8 WHO human-animal report


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