Characterisation of 16S rRNA gene, phylogenetic analysis, and multidrug resistance profiling of hospital-associated Myroides and Bacillus strains from Anambra State, Nigeria

Hospitals are places designed to heal, yet their very walls and air can sometimes harbor invisible threats. Inside these buildings, tiny bacteria live on surfaces, in the dust, and even floating in the air currents. Most of these microbes are harmless, but some are opportunistic, meaning they wait for a chance to infect people whose immune systems are already weakened. A major concern for doctors and scientists is that many of these bacteria have learned to resist the medicines meant to kill them. When a single germ survives multiple different drugs, it becomes a "multidrug-resistant" pathogen, making infections much harder to treat. To understand these invisible enemies, scientists often look at a specific part of the bacteria's genetic code, a molecular signature that acts like a fingerprint, allowing them to identify exactly what kind of organism they are dealing with and how it is related to other known bacteria.

In a recent study focused on hospitals in Awka, Nigeria, researchers set out to investigate two specific bacterial strains found in these medical environments. They were looking for clues about how these germs survive and spread, particularly focusing on their ability to resist antibiotics and their genetic makeup. The team collected samples from two very different sources: the air inside a specialist hospital ward and the clothing worn by healthcare staff. From the air, they isolated a bacterium they named Myroides sp. strain Awka-1. From the staff's attire, they found a second strain, Bacillus sp. strain Awka-1. Both of these organisms are known to be opportunistic, capable of causing trouble in vulnerable patients, but until this study, their specific genetic profiles and resistance patterns in this region were not well documented.

The researchers first tested how these bacteria reacted to a variety of common antibiotics. The results showed that both strains were indeed resistant to several types of medication. The strain found in the air resisted penicillins, cephalosporins, aminoglycosides, and quinolones. The strain found on the clothing resisted fluoroquinolones, penicillins, and phenicols. To measure just how resistant these bacteria were, the scientists calculated a resistance score for each. The airborne strain had a score of 0.5, while the clothing-associated strain had a score of 0.4. These numbers indicate that a significant portion of the antibiotics tested failed to stop the growth of these bacteria. Furthermore, the team looked inside the bacteria for plasmids, which are small, extra loops of DNA that often carry instructions for drug resistance. They found evidence of these plasmids in both strains, suggesting that these bacteria could potentially share their resistance traits with other germs around them, a process that helps dangerous traits spread quickly through a hospital.

To understand exactly what these bacteria were and where they fit in the tree of life, the researchers sequenced a specific gene known as the 16S rRNA gene. This gene is a standard tool for identifying bacteria because it changes very slowly over time, allowing scientists to trace evolutionary relationships. The genetic analysis confirmed that the airborne strain belonged to the Myroides odoratimimus family, grouping closely with other known strains of this species. The strain found on the clothing was identified as part of the Bacillus cereus complex, a group of bacteria well-known for their ability to form tough, dormant spores that allow them to survive on dry surfaces like fabric for long periods. By comparing their new genetic sequences to a massive global database, the researchers placed these Nigerian strains firmly within established groups of bacteria, confirming their identity beyond doubt.

The study highlights a specific and often overlooked pathway for infection: the air inside hospital wards and the clothes worn by the people working there. The presence of these resistant bacteria in the air suggests that ventilation systems and air currents can move germs from one place to another, while the findings on staff clothing indicate that uniforms can act as mobile reservoirs for these tough microbes. The researchers deposited their genetic data into a public international database, creating a permanent record that other scientists can use to track these specific strains in the future. While this study provides a clear snapshot of the situation in three hospitals in Anambra State, it also points to the need for broader surveillance across the country to fully understand the scale of the problem. The work serves as a foundational step, offering precise genetic markers and resistance profiles that will help health officials monitor and control the spread of these difficult-to-treat bacteria in Nigerian healthcare settings.