Project – Prevalence of Methicillin-Resistant Staphylococcus aureus (MRSA) Among Healthcare Workers. A Study of Selected wards of Abia State University Teaching Hospital, Aba, Abia State

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Healthcare-associated infections remain a major public health concern because they can increase patient morbidity, prolong hospitalisation, raise healthcare costs, and contribute to avoidable deaths. These infections may occur during the provision of medical care and can be caused by bacteria, viruses, fungi, and other microorganisms. Hospitals provide an environment in which susceptible patients, healthcare personnel, invasive medical devices, and potentially pathogenic microorganisms interact continuously. Inadequate infection prevention practices, overcrowding, inappropriate antibiotic use, and insufficient adherence to hand hygiene can increase the risk of microbial transmission within healthcare facilities. Haque et al. (2018) explained that healthcare-associated infections constitute an important challenge to patient safety and require coordinated prevention, surveillance, and control measures. In Nigeria, a systematic review by Onwuliri et al. (2025) also documented a substantial burden of healthcare-associated infections and highlighted the need to strengthen infection prevention and control programmes. These concerns make the investigation of important hospital-associated pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), relevant to the protection of both patients and healthcare workers.

Staphylococcus aureus is a Gram-positive bacterium that commonly colonises the skin and anterior nares of humans without necessarily causing disease. However, when the organism enters normally sterile tissues or encounters a susceptible host, it can cause a range of infections, including skin and soft-tissue infections, wound infections, pneumonia, bloodstream infections, and endocarditis. Its clinical importance is associated with its capacity to colonise different body sites, express virulence factors, evade certain host immune responses, and survive under a variety of environmental conditions. The bacterium may also spread between individuals through direct contact, contaminated hands, and contact with contaminated surfaces or equipment. Wertheim et al. (2005) demonstrated the epidemiological importance of S. aureus carriage in human populations and explained the relationship between colonisation and subsequent infection. Similarly, Tong et al. (2015) reviewed the clinical manifestations, pathogenic mechanisms, and treatment challenges associated with S. aureus infections. In hospital environments, understanding the carriage of this organism among healthcare workers is therefore important because colonised personnel may potentially contribute to its transmission, particularly when effective infection prevention practices are not consistently maintained.

Methicillin-resistant Staphylococcus aureus is a strain of S. aureus that has developed resistance to methicillin and related beta-lactam antibiotics, including most commonly used penicillins and cephalosporins, subject to specific exceptions and current laboratory interpretation standards. Resistance is commonly associated with the acquisition of the mecA gene, which encodes an altered penicillin-binding protein known as PBP2a and reduces the effectiveness of many beta-lactam antibiotics. Some MRSA strains carry the related mecC gene. The emergence and spread of MRSA have complicated the treatment of staphylococcal infections because antibiotics that previously provided effective treatment may no longer be suitable. Chambers and DeLeo (2009) described the evolution of MRSA as a major challenge in the history of antimicrobial resistance, while Turner et al. (2019) reviewed the epidemiology, biological characteristics, and clinical management of MRSA. The significance of MRSA extends beyond patients with active infections because individuals may carry the organism without symptoms and potentially serve as reservoirs for transmission. Consequently, investigating MRSA carriage among healthcare workers is an important component of understanding the potential circulation of resistant staphylococci within healthcare settings.

Healthcare workers, including nurses, doctors, laboratory personnel, ward attendants, and other staff who have direct or indirect contact with patients, may be exposed to MRSA during their daily professional activities. Colonisation occurs when the organism is present on or in the body without necessarily producing clinical symptoms. The anterior nares are a particularly important site for S. aureus carriage, although the throat, skin, hands, and other body sites may also harbour the organism. Colonisation does not automatically mean that a healthcare worker has an active infection or will transmit MRSA to patients; rather, it indicates the presence of a potential reservoir that may become relevant under particular circumstances. Dulon et al. (2014), in a systematic review and meta-analysis, examined the prevalence of S. aureus and MRSA carriage among healthcare workers and demonstrated the importance of occupational and epidemiological factors in understanding carriage. Similarly, a systematic review by Giri et al. (2023) assessed MRSA carriage among healthcare workers in South Asia and reported an overall pooled prevalence of 9.23% in the included populations. Such evidence illustrates the need for local studies because prevalence estimates from other geographical regions cannot automatically be applied to healthcare workers in Aba, Abia State.

The transmission of MRSA within hospitals is influenced by interactions between colonised individuals, susceptible patients, healthcare personnel, contaminated equipment, and the surrounding environment. The hands of healthcare workers are particularly important in infection transmission because they frequently come into contact with patients, wound sites, medical devices, and shared clinical equipment. If hand hygiene is inadequate, organisms may be transferred between body sites or from one patient to another. MRSA may also spread through direct skin contact and contact with contaminated objects, although the relative contribution of each route varies across settings. Mitchell et al. (2015) examined the contribution of environmental contamination to the transmission of S. aureus in hospitals, reinforcing the importance of considering both human and environmental sources in infection prevention. A systematic review by Sreeramoju et al. (2019) also found that healthcare personnel hands can harbour multidrug-resistant organisms, including MRSA, although the estimated prevalence varies substantially according to sampling methods and clinical setting. These findings support the need to investigate MRSA carriage among healthcare workers in selected wards, particularly where repeated contact with patients and contaminated materials creates opportunities for microbial transmission.

The prevalence of MRSA among healthcare workers varies between countries, hospitals, professional groups, and study populations. Differences in antibiotic exposure, infection prevention practices, occupational responsibilities, sampling sites, laboratory methods, and the characteristics of recruited participants can influence the reported prevalence. In Nigeria, Abubakar and Sulaiman (2018) conducted a systematic review of MRSA prevalence, trends, and antimicrobial susceptibility and identified important concerns regarding the burden of MRSA in the country, while also noting limitations in the available evidence. More recently, Azzam et al. (2025) examined the prevalence, antibiogram, and risk factors associated with asymptomatic MRSA carriage in Africa, highlighting the importance of surveillance among populations with potential exposure risks. Healthcare workers may differ in their likelihood of exposure because of variations in patient contact, wound care, invasive procedures, ward workload, and adherence to infection prevention measures. Nevertheless, these factors should be investigated rather than assumed to explain carriage in a particular hospital. A study involving healthcare workers in selected wards of Abia State University Teaching Hospital, Aba, can therefore provide setting-specific evidence on MRSA carriage and help determine whether the burden observed locally warrants further investigation or targeted preventive action.

Abia State University Teaching Hospital, Aba, is an appropriate setting for investigating MRSA carriage among healthcare workers because teaching hospitals provide a range of clinical services involving repeated interactions between healthcare personnel and patients. Different wards may have different patient populations, workloads, procedures, and infection prevention requirements, making ward-specific investigation useful for understanding the distribution of MRSA carriage. However, findings from other hospitals or from national-level reviews cannot establish the current prevalence among personnel working in selected wards of this institution. Local evidence is needed to determine how many healthcare workers sampled during the study are carrying MRSA, whether carriage differs across the selected wards or occupational groups, and what infection prevention implications may arise from the findings. The Centers for Disease Control and Prevention (CDC, 2024) identifies hand hygiene and other evidence-based infection prevention practices as important components of controlling the spread of MRSA in healthcare settings. In addition, the World Health Organization (WHO, 2022) recommends strengthened infection prevention and control programmes as part of efforts to reduce healthcare-associated infections. Against this background, the present study seeks to determine the prevalence of MRSA among healthcare workers in selected wards of Abia State University Teaching Hospital, Aba, Abia State, and generate evidence that may support local infection prevention strategies.

1.2 Statement of the Problem

The increasing occurrence of methicillin-resistant Staphylococcus aureus (MRSA) presents a significant challenge to infection prevention and patient safety in healthcare facilities. Unlike methicillin-susceptible S. aureus, MRSA is resistant to many commonly used beta-lactam antibiotics, making infections caused by the organism more difficult to treat. MRSA can cause serious conditions, including wound infections, pneumonia, bloodstream infections, and sepsis. Its presence in healthcare environments is particularly concerning because vulnerable patients may be exposed to the organism during treatment. Chambers and DeLeo (2009) described the emergence and spread of MRSA as a major antimicrobial resistance challenge, while the Centers for Disease Control and Prevention (CDC, 2025) continues to identify MRSA as an important cause of severe healthcare-associated infections. The problem therefore extends beyond the treatment of infected patients to include the detection and prevention of potential sources of transmission within hospitals.

A further problem is the possibility that healthcare workers may carry MRSA without displaying any clinical symptoms. Such individuals may remain unaware of their carriage status, and the organism may be transferred through direct contact or contaminated hands when appropriate infection prevention practices are not followed. However, colonisation does not necessarily mean that a healthcare worker will transmit the organism or develop an infection. Dulon et al. (2014) demonstrated that MRSA carriage among healthcare workers occurs in non-outbreak healthcare settings, highlighting the relevance of surveillance in understanding this potential reservoir. The CDC (2024) also identifies hand hygiene, appropriate protective practices, and environmental cleaning as essential components of safe healthcare delivery. Without adequate information about MRSA carriage among healthcare workers, it may be difficult for a facility to determine whether additional investigation or targeted infection prevention measures are warranted.

In Nigeria, the problem is compounded by the need for more comprehensive and geographically representative evidence on MRSA. Abubakar and Sulaiman (2018) reviewed published Nigerian studies and reported substantial variation in MRSA prevalence and antimicrobial susceptibility, illustrating the importance of considering local epidemiological conditions. Although such evidence establishes the broader relevance of MRSA in Nigeria, findings from clinical isolates obtained from infected patients cannot automatically be interpreted as the prevalence of asymptomatic carriage among healthcare workers. Similarly, results from other hospitals may not accurately represent healthcare personnel working in Aba because of differences in occupational exposure, patient populations, infection prevention practices, and study methods. This creates a need for research specifically designed to assess MRSA carriage among healthcare workers rather than relying solely on studies of clinical infections.

The specific problem addressed by this study is the absence of established, study-specific evidence on the prevalence of MRSA carriage among healthcare workers in the selected wards of Abia State University Teaching Hospital, Aba, Abia State. Without such evidence, the extent of MRSA carriage among the participating healthcare workers, its distribution across the selected wards, and its possible association with occupational and demographic characteristics remain to be determined. This study will therefore investigate MRSA carriage using appropriate microbiological procedures and analyse the results obtained from eligible participants. The findings may provide a baseline for local surveillance and help inform decisions on infection prevention, staff education, and further epidemiological investigation. The study will not assume that MRSA is already prevalent at a particular rate in the hospital; its prevalence will be established from the actual study results.

1.3 Aim and Objectives of the Study

1.3.1 Aim of the Study

The aim of this study is to determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) among healthcare workers in selected wards of Abia State University Teaching Hospital, Aba, Abia State.

1.3.2 Specific Objectives

The specific objectives are to:

1. Determine the prevalence of MRSA carriage among healthcare workers in the selected wards of Abia State University Teaching Hospital, Aba.

2. Identify the distribution of MRSA carriage among healthcare workers according to their selected wards and professional categories.

3. Determine the antibiotic susceptibility patterns of MRSA isolates recovered from participating healthcare workers.

4. Examine the association between MRSA carriage and selected demographic and occupational characteristics of healthcare workers, such as age, sex, professional category, years of service, and adherence to infection prevention practices, where these variables are measured.

1.4 Research Questions

The study will answer the following research questions:

1. What is the prevalence of MRSA carriage among healthcare workers in the selected wards of Abia State University Teaching Hospital, Aba?

2. How is MRSA carriage distributed across the selected wards and professional categories of healthcare workers?

3. What are the antibiotic susceptibility patterns of MRSA isolates recovered from participating healthcare workers?

4. Is there a significant association between MRSA carriage and selected demographic and occupational characteristics of healthcare workers?

1.5 Research Hypothesis

The following null hypothesis will guide the study:

H₀: There is no statistically significant association between selected occupational characteristics of healthcare workers and MRSA carriage in the selected wards of Abia State University Teaching Hospital, Aba, Abia State.

The hypothesis will be tested at the 0.05 level of significance, using an appropriate statistical test based on the study design, sample size, and measurement of the variables.

1.6 Significance of the Study

The findings of this study are expected to be significant to healthcare workers, hospital management, infection prevention and control teams, public health authorities, patients, and future researchers.

Healthcare workers: The study may increase awareness of asymptomatic MRSA carriage and its potential implications for occupational health and patient safety. By identifying the prevalence of MRSA carriage among participating staff, the findings may encourage improved adherence to hand hygiene, appropriate use of personal protective equipment, and established infection prevention procedures. The study may also help healthcare workers understand that the absence of symptoms does not necessarily exclude bacterial colonisation (Dulon et al., 2014).

Hospital management: The findings may provide useful information for Abia State University Teaching Hospital, Aba, in assessing the need for additional surveillance, staff education, and targeted infection prevention measures. Information about the distribution of MRSA carriage across selected wards may help the hospital identify areas requiring further assessment. However, decisions about staff screening or decolonisation should follow institutional policies, professional guidance, and appropriate clinical assessment rather than prevalence findings alone (CDC, 2024).

Infection prevention and control teams: The study may provide baseline information to support the monitoring of MRSA carriage and strengthen existing infection prevention programmes. The results could help guide training on hand hygiene, safe patient-care procedures, environmental cleaning, and the appropriate management of identified carriers. The CDC (2025) recommends evidence-based infection prevention practices to reduce MRSA transmission in healthcare facilities.

Patients: Patients may benefit indirectly if the findings contribute to improved infection prevention practices and a reduced risk of exposure to MRSA during healthcare delivery. This is particularly important for patients with surgical wounds, invasive devices, weakened immunity, or prolonged hospital stays, who may be vulnerable to healthcare-associated infections (Tong et al., 2015).

Public health authorities: The study may contribute local evidence to the broader understanding of MRSA epidemiology in Nigeria. Its findings could complement existing research and support future investigations into resistant bacterial carriage among healthcare personnel. Abubakar and Sulaiman (2018) highlighted the importance of improved MRSA surveillance in Nigeria, making additional setting-specific research relevant.

Researchers and students: The study may serve as a reference for subsequent investigations into MRSA carriage, antimicrobial resistance, healthcare-associated infections, and occupational exposure to resistant bacteria. It may also provide a basis for comparative studies involving other hospitals in Abia State and neighbouring states.

1.7 Scope of the Study

The study focuses on the prevalence of methicillin-resistant Staphylococcus aureus among healthcare workers in selected wards of Abia State University Teaching Hospital, Aba, Abia State.

The geographical scope is restricted to the selected wards of the hospital, while the population scope comprises eligible healthcare workers who provide informed consent to participate. The microbiological scope includes the collection and processing of appropriate specimens, isolation and identification of S. aureus, and determination of methicillin resistance using validated laboratory procedures.

The study will also examine the distribution of MRSA carriage according to selected wards, professional categories, and relevant demographic or occupational characteristics. Antibiotic susceptibility patterns will be assessed where the laboratory protocol includes the required tests. The study will not automatically establish that MRSA-positive healthcare workers have active infections or have transmitted the organism to patients. Carriage and transmission are distinct outcomes, and demonstrating transmission would require additional epidemiological evidence, potentially including molecular typing (Price et al., 2017).

1.8 Limitations of the Study

The study may encounter limitations associated with sample size, the availability of eligible participants, access to relevant occupational information, and the sensitivity of the microbiological methods used. A relatively small sample may limit the precision of the prevalence estimate and the ability to detect statistically significant associations between MRSA carriage and specific occupational characteristics.

The choice of sampling site may also affect the findings. For example, nasal screening alone may fail to identify individuals carrying MRSA at other body sites. Consequently, the results will need to be interpreted in relation to the specimen collection protocol and the laboratory methods used.

Furthermore, because the study is restricted to selected wards in one teaching hospital, the findings may not be generalisable to all healthcare workers in Aba, Abia State, or Nigeria. A cross-sectional assessment will also establish carriage at the time of sampling rather than demonstrate persistent colonisation or direct transmission between healthcare workers and patients.

These limitations will be addressed, where possible, through appropriate sampling procedures, validated laboratory methods, accurate data collection, and transparent reporting of the study findings.

1.9 Operational Definition of Terms

Prevalence: The proportion of healthcare workers sampled during the study who test positive for MRSA, expressed as a percentage.

Methicillin-resistant Staphylococcus aureus (MRSA): A strain of Staphylococcus aureus identified as resistant to methicillin or an appropriate surrogate agent using recognised laboratory criteria.

Healthcare workers: Personnel involved in providing, supporting, or delivering healthcare services in the selected wards, including eligible nurses, doctors, laboratory personnel, and other relevant clinical staff.

Colonisation: The presence and multiplication of a microorganism on or within the body without necessarily causing signs or symptoms of active infection.

MRSA carriage: The detection of MRSA in a specimen collected from a healthcare worker, according to the study’s approved sampling and laboratory procedures.

Antibiotic susceptibility pattern: The observed response of a bacterial isolate to selected antimicrobial agents, interpreted according to recognised laboratory standards.

Selected wards: The specific hospital wards included in the study according to the approved sampling plan.

Healthcare-associated infection: An infection associated with receiving healthcare that was not present or incubating at the time of the relevant healthcare encounter, according to the applicable surveillance definition.

Infection prevention and control: Evidence-based policies and practices intended to prevent or reduce the transmission of infectious agents in healthcare settings.

Asymptomatic carrier: An individual who carries a microorganism without displaying symptoms attributable to an active infection at the time of assessment.

Project – Prevalence of Methicillin-Resistant Staphylococcus aureus (MRSA) Among Healthcare Workers. A Study of Selected wards of Abia State University Teaching Hospital, Aba, Abia State