Antimicrobial Susceptibility Profiles, Multidrug Resistance Patterns, and MAR Index Analysis of Campylobacter jejuni and Campylobacter coli Isolated from Poultry and Chicken Handlers in Maiduguri, Northeast Nigeria

In the bustling markets of northeastern Nigeria, where live chickens are traded daily, a silent battle is being waged between bacteria and the medicines meant to stop them. The enemy is a group of bacteria called Campylobacter, which naturally lives in the guts of birds and can cause severe stomach illness in humans who eat undercooked poultry or handle infected birds. For decades, farmers have used antibiotics to keep their flocks healthy and to help them grow faster. However, when these drugs are used too often or without a doctor's order, the bacteria learn to survive them. This survival skill is called antimicrobial resistance. It is a growing global crisis because when bacteria become resistant, the medicines that usually cure human infections stop working. In many parts of the world, scientists have found that bacteria from poultry are becoming harder to treat, but in the remote, conflict-affected regions of northeastern Nigeria, there was almost no information about what these bacteria were doing or how they were changing.

A team of researchers set out to fill this gap of knowledge in Maiduguri, a major city in Borno State. They visited six live bird markets to collect samples from the birds and from the hands of the people who sold them. Their goal was simple: to see which antibiotics the bacteria could still be killed by and which ones they had learned to ignore. They tested forty-nine confirmed samples of the bacteria against ten different antibiotics commonly used in medicine and farming. They also looked for specific genetic instructions inside the bacteria that allowed them to resist certain drugs, and they calculated a score to determine if the bacteria came from an environment where antibiotics were used heavily.

The results painted a clear and concerning picture of the situation on the ground. The bacteria showed the strongest resistance to tetracycline, a common antibiotic used in agriculture. More than one-third of the bacteria collected were able to survive exposure to this drug. Resistance to another drug, norfloxacin, was also significant, affecting nearly a quarter of the samples. However, the study found a glimmer of hope in the form of three other antibiotics: ciprofloxacin, levofloxacin, and erythromycin. Every single bacteria sample tested was still vulnerable to these drugs, meaning they could still be used effectively to treat infections in this region. This is a critical finding because erythromycin is often the first choice for treating severe stomach infections in humans, and its effectiveness here suggests that the most important treatments remain available.

Despite the good news regarding those three drugs, the overall pattern of resistance was complex. The researchers found that more than half of the bacteria samples were multidrug resistant, meaning they had learned to survive at least one drug from three different families of antibiotics. This is not just a case of a single bug resisting a single pill; it is a sign that the bacteria have been exposed to a wide variety of medicines. To understand where these tough bacteria came from, the scientists calculated a resistance score for each sample. A high score indicates that the bacteria likely originated from an environment where antibiotics are used frequently and without strict control. In this study, the scores were high, confirming that the bacteria in these markets are living in a world saturated with antibiotic pressure.

The investigation went deeper than just testing how the bacteria reacted to drugs in a lab dish. The researchers used molecular tools to find the specific genetic codes that allowed the bacteria to resist tetracycline and erythromycin. They found the gene responsible for tetracycline resistance in the bacteria, which matched the high rates of resistance they saw in the lab tests. They also found the gene for erythromycin resistance, even though the bacteria still appeared to be killed by the drug in the lab. This suggests that the bacteria are carrying the hidden instructions for resistance, waiting for the right conditions to become fully active. This discovery is important because it means the potential for total drug failure is already present, even if the drugs are still working for now.

The study concludes that the situation in Maiduguri's live bird markets is a public health concern that requires immediate attention. The high rate of bacteria that can resist multiple drugs, combined with the presence of resistance genes, signals that the current way antibiotics are used in poultry is unsustainable. The researchers recommend that access to antibiotics for farm animals be strictly controlled and that farmers be educated on how to use these medicines responsibly. While the current effectiveness of ciprofloxacin, levofloxacin, and erythromycin offers a window of opportunity for treating human infections, the study warns that this window could close quickly if the misuse of antibiotics continues. The findings serve as a urgent call to action to monitor these bacteria closely and to change how antibiotics are managed to prevent the spread of untreatable infections from the farm to the human population.