Journal of Bacteriology & Parasitology

Prevalence and Risk Factors of Staphylococcus aureus Infection in Hospitalized Patient in Tirana

Blerta Kika^1*, Erjona Abazaj¹, Oltiana Petri¹ and Andi Koraqi^{2 1}Institute of Public Health, Tirana, Albania
²Faculty of Medicine, University of Tirana, Albania
^*Correspondence: Blerta Kika, Institute of Public Health, Tirana, Albania, Email:

Received: 03-Sep-2018 Published: 25-Oct-2018

Introduction

Staphylococci are Gram-positive bacteria, with diameters of 0.5–1.5 μm and characterized by individual cocci, which divide in more than one plane to form grape-like clusters [1-4]. Till date, there are 32 species and eight sub-species in the genus Staphylococcus , many of which preferentially colonize in the human body [5,6]. Only Staphylococcus aureus and Staphylococcus epidermidis are significant in their interactions with humans. S. aureus is considered to be a major pathogen that colonizes and infects both hospitalized patients with decreased immunity, and healthy immuno-competent people and animals in the community [7,8]. This bacterium was found naturally in different parts of some animals and also in human body like, the nares (primary reservoir), pharynx, axilla, groin, vaginal cavity, in gastrointestinal tract, or damaged skin surfaces etc. and is a diseaseproducing pathogen [7].

S. aureus is a major human pathogen that causes a broad range of serious diseases in humans, associating with numerous mild skin and soft tissue infections, as well as life-threatening pneumonia, bacteraemia, osteomyelitis, endocarditis, sepsis, and toxic shock syndrome [8-11].

Staphylococcus aureus bacteremia (SAB) is an important infection with an incidence rate ranging from 20 to 50 cases/100,000 population per year. Between 10% and 30% of these patients will die from SAB. Comparatively, this accounts for a greater number of deaths when compared with AIDS, tuberculosis, and viral hepatitis combined [12]. There are many cases about the situation in hospital-associated (HA) and community-associated (CA) S. aureus infection in Albanian population [13-15]. The main goal of our research is to investigate the prevalence of Staphylococcus aureus in hospital-associated infection in Hospital Centre of Tirana.

Materials and Methods

This is a retrospective study conducted in tertiary University Hospital Center “Mother Theresa” from October 2014 to December 2017. Patients (aged 18 years or older) enrolled in this study were hospitalized in different wards such as surgery, dermatology, nephrology, cardiology, neurology, infection diseases, cardiology, hemodialysis etc. About 258 clinical specimens were collected based on infection type such as wound, pus/exudates, blood, urine, sputum, and indwelling medical devices. All specimens were sent to the microbiology laboratory within one hour. A standardized questionnaire was used to collect socioeconomic and demographic data from medical personalized files of each patient. The demographic data included age, sex, school education, residence (urban/rural), marital status, number of children, etc. We isolated and identified S. aureus on the basis of colony morphology and also we used standard tests like catalase, coagulase, and growth on mannitol salt agar. For statistical analysis, all the data were expressed in frequencies and percentages. Chi-square test and Fisher's exact test were used to determine relationships between categorical variables. In the univariate analyses of risk factors; age, number of household, and income were categorized. A p value<0.05 indicated a statistically significant difference in all tests. All data collected from the medical files of each patient were analyzed by SPSS version 20.0 (SPSS Inc., Chicago, IL, USA).

Results

A total of 258 patients from Mother Theresa University Hospital Center in Tirana were enrolled during the study period. The sociodemographic and clinical characteristics of 258 patients are shown in Table 1. Among the age groups, the most predominant age was patients older than 46 years. For the age groups; marital status, school education, social level and underlying medical conditions of patients we did not find any significant association.

Table 1: Demographic characteristics of patients admitted to Mother Theresa Hospital Center.

In Table 2, Sample distribution among patients attending to different wards in Mother Theresa University Hospital Center and prevalence of S. aureus among each of them are shown.

Table 2: Samples distribution among patients attending to different wards in University Hospital Center Mother Theresa and prevalence of S. aureus among each of them

Table 3 shows the prevalence of infection with S. aureus based on source of clinical specimens. Most of samples were collected from skin and soft-tissue infections, urine infections and from nasal, sputum and ear swab cases.

Table 3: Prevalence of infection with S. aureus based to source of clinical specimens

Discussion

In this study we evaluated the prevalence and risk factors for S. aureus among adult patients admitted to a tertiary University Hospital Center in Tirana, Albania. The prevalence of S. aureus infection of patients was 36%. The prevalence of S. aureus at hospital admission observed in our study is higher than the prevalence published in previous reports conducted in Albania one in 2007 and the other one in 2016 with prevalence of S. aureus 18.2% and 9.6% respectively [16,17]. There were significant associations between sociodemographic characteristics and wound colonization by S. aureus . Most patients (65.1%) were male, with a significant association with women (p value =0.009). People in rural areas have a high prevalence compared to people that live in urban area, and in this case, we have found a significance level 0.02.

We think that the higher prevalence observed in our study was from differences in patient demographic characteristics and underlying medical problems. Many studies have evaluated the risk factors associated with S. aureus infection. The significant risk factors for S. aureus infection were age, sex, underlying medical problems (as having a chronic disease, surgical operation, diagnosis of skin or soft tissue lesions) [16,18-26].

In this study, there are significant associations with sex, living area, sample distribution among wards and also the source of clinical specimens. Many studies reported significant associations for different age groups. Some of them have found significance among 10-20 age groups [26,27]. Another study has found significance among 18-40 years and more than 60 years [23]. Faria et al, has found a logistic regression for older age more than 40 years as a risk factor for S. aureus infection. But in this study we did not find an association between the age groups. We did not find an association for marital status, school education (level), social level or underlying medical conditions of patients.

The most frequent samples were collected from dermatology, nephrology and infectious disease wards. In Infectious diseases wards, the prevalence for S. aureus were resulted to be 21.5%, which was the highest prevalence in this study based on the samples collected from the wards. In dermatology samples the prevalence was 19.4 %, and in nephrology 15%. Surgical wards had a prevalence of 11.8%, and cardiology, neurology and hemodialysis wards had the same prevalence of 7.5%. Based on Pearson Chi-Square 43.1 p value resulted<0.0001, for CI 95% (34-76).

For clinical specimens, 258 cases in total were collected based on infection type such as wound, pus/exudates, blood, urine, sputum and indwelling medical devices. Out of all 93 cases isolated with S. aureus , 25% were from urine infections; 24.6 % from skin and soft-tissue infections cases; 20.4% from vaginal and urethral swab; 15% from nasal and ear swab cases and 15% from blood stream, indwelling medical devices and catheter-associated infections. We did find statistically significant differences between infection and place where the samples were collected p<0.0001 Chi-Square 35.92 CI 95% (23.9-56.8).

Summary

The rate of prevalence of S. aureus in hospitalized patients in this study was high. These results indicated that this type of infection is a significant concern for health services and patients. The highest percentage of S. aureus found in surgical and non-surgical wounds suggested that further investigation should be implemented. A screening of all hospitalized cases can lead to a reduction in the incidence of this infection in the hospital environment and also will help to control the risk factors.

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