April 3, 2017 The growth of Neisseria meningitidis colonies on New York City Medium Agar. Credit: Wikipedia

Neisseria meningitidis, a bacterium usually associated with meningitis and sepsis, is the cause of a recent cluster of sexually transmitted infections in Columbus, Ohio and in other US cities. The bacterium appears to be adapting to a urogenital environment, an analysis of the organism's DNA shows.

The DNA analysis helps doctors track the spread of this type of bacteria, distinguish it from others, anticipate which vaccines might be protective, and understand how it has evolved.

The findings are scheduled for publication in PNAS.

Genetic changes make this "clade" of N. meningitidis look more like relatives that are known to cause gonorrhea, says lead author Yih-Ling Tzeng, PhD, assistant professor of medicine (infectious diseases) at Emory University School of Medicine.

In particular, the bacteria have lost their outer coat-capsules, potentially enhancing their ability to stick to mucosal surfaces in the body, and have gained enzymes that promote growth in a low-oxygen environment.

Some good news is that the capsule-less organism is less likely to cause invasive diseases such as meningitis, because the capsule protects the bacteria against components of the immune system found in the blood, Tzeng says.

N. meningitidis is carried at the back of the nose and throat, without symptoms, in 5 to 10 percent of people. As its name suggests, when N. meningitidis invades other parts of the body, it can cause meningitis, an infection of the lining of the brain and spinal cord, as well as deadly bloodstream infections.

In 2015, N. meningitidis began to appear in heterosexual men coming to the Sexual Health Clinic in Columbus as the cause of urethritis: inflammation leading to painful urination. These infections were initially presumed to be gonorrhea, caused by N. gonorrhoeae. More than 100 cases have been reported in Columbus, and the same type of N. meningitidis infection has appeared in Michigan, Indiana and Georgia.

Jose Bazan, DO, the Clinic's medical director and assistant professor of medicine (infectious diseases) at Ohio State University and Abby Norris Turner PhD, assistant professor of medicine (infectious diseases) teamed up with Tzeng and David Stephens, MD, professor of medicine of Emory University School of Medicine, and colleagues from Indiana University School of Medicine and the Centers for Disease Control and Prevention (CDC) to investigate.

The Columbus clinic is part of the CDC's nationwide Gonococcal Isolate Surveillance Project (GISP), which monitors antibiotic resistance. Emory co-authors include Carlos del Rio, MD, professor of medicine and global health and director of the Atlanta GISP laboratory, and Timothy Read, PhD, associate professor of medicine and human genetics.

The scientists looked at the genomes of 52 N. meningitidis samples from Columbus, and two from Indianapolis and two from Atlanta. All 56 genomes had many common features, so they're closely related, but they are continuing to evolve.

N. meningitidis is usually classified by serogroups, based on the structure of the capsule. . Vaccines against the A, C, Y, and W serogroups have been available in the US for years, and vaccines against serogroup B were introduced in 2014.

Outbreaks of N. meningitidis serogroup C meningitis and sepsis have been observed in several countries among men who have sex with men. In contrast, the bacteria described in the PNAS paper could not be assigned to any serogroup based on initial screening tests.

The loss of several genes for synthesizing components of the capsule explains the blank result, Tzeng says. However, clues in the DNA of the capsule-less bacteria make them look like they were originally derived from a serogroup C ancestor.

It is possible that vaccines that were approved in the last few years against the B serogroup might still be effective against this meningococcal clade, because the capsule-less bacteria continue to produce other proteins targeted by those vaccines, the scientists found. A vaccine against gonorrhea has been a challenge, because repeat infections are common.

N. meningitidis doesn't usually encounter low-oxygen conditions, but this clade, linked to urethritis, has picked up genes that help them to grow in the environment of the urogenital tract. Based on their sequences, the genes appear to have come directly from N. gonorrhoeae, suggesting that on at least one occasion, the two types of bacteria were in the same place and exchanged DNA.

"All the urethritis patients responded to standard treatments for gonorrhea and there were no alarming resistance markers," Tzeng says. "However, as the gene conversion demonstrates, this clade can readily take up DNA from gonococci and it is not unthinkable that gonococcal antibiotic resistance genes could jump into this clade by gene transfer, if it is to its advantage."

Explore further: Harmless bacteria may be helpful against meningococcal outbreaks

More information: Emergence of a new Neisseria meningitidis clonal complex 11 lineage 11.2 clade as an effective urogenital pathogen, PNAS, http://www.pnas.org/cgi/doi/10.1073/pnas.1620971114

Nasal drops of harmless bacteria can inhibit a related bug that sometimes causes meningococcal disease, according to new findings published online in Clinical Infectious Diseases. The studyconducted among college students, ...

University of York scientists have shed new light on why teenagers and young adults are particularly susceptible to meningitis and septicaemia.

Scientists at Oxford University have identified the key groups of bacteria responsible for the majority of meningococcal disease cases in England and Wales over the past 20 years.

A study conducted by UCSF Benioff Children's Hospital Oakland Research Institute (CHORI) scientists shows greatly improved protective antibody responses to a new mutant vaccine antigen for prevention of disease caused by ...

Simon Fraser University researcher Lisa Craig is part of an international team that has uncovered new details about a microbe that invades the brain, sometimes with fatal results. The information is a critical piece of the ...

A team of international researchers has moved a step closer to developing a vaccine to protect against middle ear infection, currently the most common infection in children under the age of five. The vaccine could also be ...

Infection with reovirus, a common but otherwise harmless virus, can trigger the immune system response to gluten that leads to celiac disease, according to new research from the University of Chicago and the University of ...

A new study led by Rutgers clinician and researcher Mark Einstein is examining a revolutionary way to block transmission of human papillomavirus (HPV), the organism that causes 99 percent of cervical cancers, using a topical ...

Lactate produced in the upper throat might trigger meningitis-causing bacterial cells to detach from tiny colonies and spread within the body, according to a new study published in PLOS Pathogens.

Yale researchers are studying kidney and liver diseases to determine which genes are involved in the formation of cysts.

An antibody treatment successfully protected nonhuman primates against the deadly Marburg and Ravn viruses even when given five days after becoming infected, according to the latest findings of a collaborative team from The ...

Developed by Dr Tristan Clark, an associate professor in infectious diseases at the University of Southampton and colleagues at the NIHR Southampton Biomedical Research Centre, the 'point-of-care' testing strategy can be ...

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Originally posted here:

Meningitis bacteria adapting to STI niche, genetic analysis shows - Medical Xpress