Project – Antibiotic resistance profile of coagulase negative staphylococci and Staphylococcus Aureus Isolated from wound infections

CHAPTER ONE

1.1 Background of the Study

Wound infections are a significant cause of morbidity and mortality globally, especially in developing countries where healthcare systems may be under-resourced. These infections result from the invasion of pathogens into a disrupted skin barrier, often exacerbated by poor hygiene, delayed treatment, or hospital-acquired infections. Among the myriad of microorganisms implicated in wound infections, Staphylococcus aureus and coagulase-negative staphylococci (CoNS) are among the most frequently isolated Gram-positive pathogens (Otto, 2013).

Staphylococcus aureus is a versatile and opportunistic pathogen capable of causing various infections ranging from minor skin lesions to life-threatening systemic diseases. Coagulase-negative staphylococci, once considered mere contaminants, are now recognized as emerging pathogens, particularly in nosocomial settings (Becker et al., 2014). The clinical significance of these organisms is heightened by their increasing resistance to multiple antibiotics, including beta-lactams, macrolides, and even last-resort antibiotics such as vancomycin (Seng et al., 2017).

The global rise in antibiotic resistance poses a severe threat to public health. Resistance in staphylococci, especially methicillin-resistant Staphylococcus aureus (MRSA), has made the treatment of wound infections more complicated and costly. Similarly, multidrug-resistant CoNS strains have been implicated in chronic and recurrent infections, particularly in immunocompromised patients (Czekaj, Ciszewski, & Szewczyk, 2015). Therefore, understanding the antibiotic resistance patterns of these organisms is crucial for effective empirical therapy and infection control.

The resistance profiles of bacterial pathogens vary geographically and are influenced by local antibiotic prescribing practices and infection control measures. Hence, periodic surveillance and resistance profiling are necessary to guide empirical treatment and antibiotic stewardship programs (Ventola, 2015). In Nigeria, there is a growing concern about the overuse and misuse of antibiotics, leading to increased resistance rates among both community-acquired and hospital-acquired pathogens (Onoh et al., 2013).

This study seeks to evaluate the antibiotic resistance profiles of Staphylococcus aureus and CoNS isolated from wound infections in a clinical setting. The findings will help improve antibiotic selection and policy-making aimed at curbing the spread of resistant strains.

1.2 Statement of the Problem

The rising prevalence of antibiotic-resistant Staphylococcus aureus and coagulase-negative staphylococci (CoNS) has become a significant public health concern, particularly in the context of wound infections. These organisms, once treatable with conventional antibiotics, are increasingly displaying resistance to multiple drug classes. This resistance undermines the effectiveness of standard therapies and complicates clinical decision-making. As a result, infections that were previously easy to manage now pose serious therapeutic challenges, especially in resource-limited settings.

In Nigeria, several factors contribute to the growing problem of antibiotic resistance. Chief among these is the widespread and often unregulated use of antibiotics both in healthcare facilities and within the general population. Antibiotics are frequently purchased over the counter without prescriptions, and patients may fail to complete their doses, promoting the survival of resistant strains. Moreover, poor hygiene and infection control practices in many health institutions further facilitate the transmission of resistant bacteria, including MRSA and multidrug-resistant CoNS.

Another critical issue is the lack of consistent and up-to-date surveillance data on bacterial resistance patterns. Many healthcare facilities do not routinely conduct microbiological testing to guide treatment choices. This gap in data means clinicians often rely on empirical therapies based on outdated or generalized information, which may not reflect the current resistance trends in their specific locality. Such empirical treatments are prone to failure, further driving the cycle of resistance and patient deterioration.

The consequences of ineffective treatment are far-reaching. Patients with resistant wound infections often experience prolonged hospital stays, repeated antibiotic courses, surgical interventions, or even amputations. These complications place a substantial burden on healthcare systems already struggling with limited resources. Additionally, the economic cost to patients and their families—ranging from lost income to high out-of-pocket treatment expenses—can be devastating.

Given these challenges, there is an urgent need to assess the current antibiotic resistance profiles of Staphylococcus aureusand CoNS in wound infections within Nigerian healthcare settings. Accurate data will inform appropriate treatment protocols, support antimicrobial stewardship, and contribute to broader national and global efforts to combat antimicrobial resistance. Without timely interventions and evidence-based practices, the threat posed by resistant staphylococcal infections will continue to grow unchecked.

1.3 Objectives of the Study

General Objective:

To determine the antibiotic resistance profiles of Staphylococcus aureus and coagulase-negative staphylococci isolated from wound infections.

Specific Objectives:

1. To isolate and identify Staphylococcus aureusand CoNS from wound swabs.
2. To determine the antibiotic susceptibility patterns of the isolates using standard disc diffusion methods.
3. To compare the resistance profiles between Staphylococcus aureusand CoNS.
4. To identify the prevalence of multidrug resistance among the isolates.

1.4 Research Questions

1. What is the prevalence of Staphylococcus aureusand CoNS in wound infections?
2. What are the antibiotic susceptibility patterns of the isolated strains?
3. Are there significant differences in the resistance profiles of Staphylococcus aureusand CoNS?
4. What proportion of the isolates exhibit multidrug resistance?

1.5 Hypotheses

• H₀₁: There is no significant difference in the antibiotic resistance profiles of Staphylococcus aureus and CoNS isolated from wound infections.
• H₀₂: The prevalence of multidrug resistance among the isolates is not statistically significant.

1.6 Significance of the Study

This study is significant as it addresses the pressing need for localized epidemiological data on the antibiotic resistance profiles of Staphylococcus aureus and coagulase-negative staphylococci (CoNS) isolated from wound infections. With the rising incidence of antimicrobial resistance, particularly among Gram-positive pathogens, this research will provide critical insights into the current resistance patterns in a specific clinical setting. Such data are essential for improving diagnostic accuracy and guiding effective therapeutic interventions.

One of the primary beneficiaries of this study will be clinicians. The results will offer evidence-based guidance for selecting appropriate empiric antibiotic therapies for wound infections, reducing the trial-and-error approach often employed due to the lack of localized resistance data. Timely and accurate treatment not only enhances patient outcomes but also limits the spread of resistant strains by ensuring appropriate antibiotic use from the onset of infection.

Microbiologists and laboratory scientists will also benefit from the findings of this research. By analyzing resistance trends among clinical isolates, laboratory personnel can better anticipate the evolving antimicrobial susceptibility patterns within their facilities. This will aid in refining standard laboratory protocols, updating testing panels, and enhancing diagnostic services to reflect current microbial behaviors in their region.

Furthermore, the study holds value for public health stakeholders and policymakers. The findings can inform antimicrobial stewardship programs, promote rational drug use policies, and guide investment in infection prevention and control strategies. With Nigeria facing rising antibiotic misuse and increasing resistance rates, evidence-based policies are urgently needed to mitigate the growing threat of antimicrobial resistance at both community and hospital levels.

Academically, the study will enrich the existing literature on antibiotic resistance in sub-Saharan Africa, where such data remain relatively sparse. It will serve as a useful reference point for future investigations and provide a foundation for longitudinal studies tracking resistance trends over time. The research may also encourage similar studies in other regions, thereby promoting a broader and more comprehensive understanding of resistance dynamics across the continent.

Lastly, the study will contribute to global efforts aimed at combating antimicrobial resistance, aligning with initiatives by the World Health Organization (WHO) and other international health bodies. By generating quality data from Nigeria, this research adds to the global database necessary for tackling resistance on an international scale. The study’s outcomes will thus have implications beyond the local context, supporting worldwide public health surveillance, policy formulation, and collaborative interventions.

1.7 Scope of the Study

This research focuses on the isolation, identification, and antibiotic susceptibility profiling of Staphylococcus aureusand coagulase-negative staphylococci from wound infections. It will be conducted in a selected healthcare facility in Nigeria using wound swab samples collected from patients presenting with various types of wounds. Only aerobic bacterial isolates will be considered, and molecular identification or resistance gene profiling will not be included.

1.8 Operational Definition of Terms

• Wound Infection: The invasion and multiplication of pathogenic microorganisms in a wound, causing local or systemic signs of infection.
• Antibiotic Resistance: The ability of bacteria to survive and multiply despite the presence of antibiotics that normally kill or inhibit them.
• Coagulase-Negative Staphylococci (CoNS): A group of staphylococcal species that do not produce the enzyme coagulase and are often less virulent than Staphylococcus aureus.
• Multidrug Resistance (MDR): Resistance of a microorganism to three or more classes of antibiotics.
• Disc Diffusion Method: A laboratory technique used to determine the susceptibility of bacteria to antibiotics by measuring zones of inhibition around antibiotic-impregnated discs.

Project – Antibiotic resistance profile of coagulase negative staphylococci and Staphylococcus Aureus Isolated from wound infections