Prevalence of nasal carriage and diversity of Staphylococcus aureus among inpatients and hospital staff at Korle Bu Teaching Hospital, Ghana

https://doi.org/10.1016/j.jgar.2013.05.006Get rights and content

Abstract

There is a paucity of data on Staphylococcus aureus epidemiology in Africa. Prevalence of nasal carriage and genetic diversity of S. aureus were determined among hospital staff (HS) and inpatients (IP) at the largest hospital in Ghana. In total, 632 nasal swabs were obtained from 452 IP and 180 HS in the Child Health Department (CHD) and Surgical Department (SD). S. aureus carriage prevalences were 13.9% in IP and 23.3% in HS. The chance of being a carrier was higher in HS (P = 0.005) and IP staying ≤7 days in hospital (P = 0.007). Resistance to penicillin (93%), tetracycline (28%) and fusidic acid (12%) was more common than for other agents (<5%). A higher chance of multidrug-resistant S. aureus carriage was observed among IP compared with HS (P = 0.01). High genetic diversity was shown by spa typing, with 55 spa types found among 105 isolates; the predominant spa types were t355 (10%) and t084 (10%). MRSA was detected in six IP with an overall carriage prevalence of ca. 1.3%, but not in HS. All three MRSA isolates from SD belonged to ST88–SCCmec IV, and two of them displayed the same spa type and antibiograms; three MRSA isolates from CHD belonged to distinct lineages (ST88–SCCmec IV, ST8–SCCmec V and ST72–SCCmec V). Altogether, these data indicate a high diversity of S. aureus, low levels of MRSA carriage, and a higher chance of nasal carriage of multidrug-resistant S. aureus among IP compared with HS in this hospital.

Introduction

Staphylococcus aureus is an important pathogen associated with human infections in hospitals and communities worldwide [1]. Asymptomatic nasal carriage ranges between 15% and 40% of a population and is an established risk factor for S. aureus infection as well as for transmission between patients and healthcare workers [2], [3].

Meticillin-resistant S. aureus (MRSA) infections are a major healthcare and socioeconomic problem in hospitals worldwide as they are more difficult and expensive to treat compared with infections caused by meticillin-susceptible S. aureus (MSSA) strains [4]. Efforts to diminish the spread of MRSA in hospitals are therefore pivotal and may include various infection control initiatives such as improved hand hygiene, rapid diagnostics, and eradication of MRSA in asymptomatic carriers especially prior to surgery [1], [5].

Data on carriage, antibiotic susceptibility patterns and the molecular epidemiology of S. aureus in the African continent are limited. S. aureus carriage prevalences of 17–46% have been found among patients and hospital personnel in Somalia and Sudan [6], [7]. A prevalence of 29% was reported by a recent study investigating S. aureus carriage in a remote indigenous population in Central Gabon [8]. Data available from different African countries indicate a prevalence of MRSA ranging from 4.8% to 20% in clinical isolates [9], [10], [11].

The objective of this large-scale surveillance study was to determine the prevalence of nasal carriage, antimicrobial susceptibility patterns and clonal diversity of S. aureus and MRSA among inpatients (IP) and hospital staff (HS) at the largest hospital in Ghana.

Section snippets

Study design, site and population

A cross-sectional study was conducted between September 2011 and May 2012 at Korle Bu Teaching Hospital, Ghana, which has over 2000 beds and an average admission of 250 patients daily. The hospital serves a population of over 3 million and acts as a major referral health facility for an estimated population of 24 million people across Ghana.

Nasal screening of IP and HS was conducted at the Child Health Department (CHD) (bed size, 168; staff, 180) and Surgical Department (SD) (bed size, 242;

Nasal carriage

Demographic characteristics of the study population are shown in Table 1. Distributions of S. aureus carriers and non-carriers stratified by population characteristics are shown in Table 2. A total of 632 participants were recruited, including 452 IP (71.5%) and 180 HS (28.5%). S. aureus was isolated from 105/632 (16.6%) of the study population. The S. aureus carrier prevalence in the two groups was 63/452 (13.9%) in IP and 42/180 (23.3%) in HS. HS had a higher chance of being S. aureus

Discussion

This is the first baseline study that provides insight into the prevalence of nasal carriage, antimicrobial susceptibility and clonal structure of S. aureus and MRSA among IP and HS in Ghana. The study reveals a statistically significant lower S. aureus carrier prevalence among IP (13.9%) compared with HS (23.3%). The difference in S. aureus carrier prevalence among IP and HS could be due to the observation that ≥44% of the IP received antibiotic therapy at the time of sampling. In line with

Funding

This study was supported by the Antibiotic Drug Use, Monitoring and Evaluation of Resistance (ADMER) project funded by the Danish International Development Agency (DANIDA).

Ethical approval

Ethical approval was obtained from the University of Ghana Medical School Ethical and Protocol Review Board (Accra, Ghana) [reference no. MS-EI/M.9 – P.3.212010-11].

Competing interests

None declared.

Acknowledgments

Prof. Bamenla Goka and Dr Clegg Lamptey, heads of the Child Health Department and Surgical Department at Korle Bu Teaching Hospital (Ghana), are thanked for their support to the study. The authors are grateful to Stephen Osei-Wusu, Lone Ryste Kildevang Hansen and Julie Hindsberg Nielsen for their technical support.

References (30)

  • A.O.A. Ahmed et al.

    Surgical-site infections in a Sudanese university hospital

    Journal of Clinical Microbiology

    (1998)
  • A.N. Ulysse et al.

    Epidemiology and population structure of Staphylococcus aureus in various population groups from a rural and semi urban area in Gabon, Central Africa

    Acta Tropica

    (2012)
  • S. Breurec et al.

    Epidemiology of methicillin-resistant Staphylococcus aureus lineages in five major African towns: emergence and spread of atypical clones

    Clinical Microbiology and Infection

    (2010)
  • B. Ghebremedhin et al.

    Emergence of a community-associated methicillin-resistant Staphylococcus aureus strain with a unique resistance profile in Southwest Nigeria

    Journal of Clinical Microbiology

    (2009)
  • A.O. Shittu et al.

    Antibiotic resistance and molecular epidemiology of Staphylococcus aureus in Nigeria

    BMC Microbiology

    (2011)
  • Cited by (42)

    • Whole-genome sequence profiling of antibiotic-resistant Staphylococcus aureus isolates from livestock and farm attendants in Ghana

      2020, Journal of Global Antimicrobial Resistance
      Citation Excerpt :

      Of note, the MRSA isolates detected were from farm attendants and belonged to ST152 and ST8 lineages, suggesting that these attendants could be sources for transmission of these resistant epidemic clones to the livestock. ST152 was the dominant clone in a collection of isolates from clinical and carriage sources in previous studies in Ghana; however, none were MRSA. [7–10]. Interestingly, ST152 MRSA has been described in Central Europe, the Balkans, Switzerland, and Denmark as a community-associated (CA)-MRSA [31].

    • Staphylococcus aureus nasal carriage among healthcare workers, inpatients and caretakers in the Tamale Teaching Hospital, Ghana

      2020, Scientific African
      Citation Excerpt :

      S. aureus nosocomial infection is the most common in North American (26.0%), Latin America (21.0%) and the second most common in Europe (19.5%) [3]. In Ghana S. aureus nosocomial infection rate is relatively high, with an estimated nasal carriage rate of 23.3% among healthcare workers, and 13.9% in inpatients [12]. The ecological niche and virulence nature of S. aureus coupled with the rising concerns of antibiotics resistance, could justify the need for healthcare facilities monitor the nasal carriage rate of their staff, patients, and caretakers in order to pre-empt possible sources of S. aureus associated outbreaks.

    View all citing articles on Scopus
    View full text