Multiple antibiotic resistant Staphylococcus aureus is one of the common causes of severe nosocomial infections, and the gastrointestinal tract is an important source of its transmission. This study assessed the previous usage of antibiotics by healthy adults (university students and villagers) in Amassoma, Nigeria, and investigated the antimicrobial resistance patterns of their intestinal S. aureus isolates. A questionnaire was used for evaluating the previous usage of antibiotics by the volunteers. Stool samples were collected and cultured, and S. aureus isolates were confirmed using standard microbiological protocols. Their antimicrobial resistance patterns were determined using disc-diffusion and agar dilution techniques. In total, 54 (45.0%) volunteers used antibiotics on self-medications, and the practice was significantly higher (p=0.01) among the villagers than among the students. The level of judicious use of prescribed antibiotics was significantly higher (p=0.003) among the students than among the villagers. Thirty-eight (31.7%) healthy adults were colonized with intestinal S. aureus. The percentages of resistance of the isolates to some antibiotics were as follows: ampicillin-68.4%, doxycycline-60.5%, cefoxitin-34.2%, vancomycin-36.8%, erythromycin-34.2%, and gentamicin-5.3%. Twenty-five (65.8%) of the isolates were multidrug-resistant. The need for sound education on the appropriate use of antibiotics and the importance of proper personal hygiene as means of controlling the spread of bacterial antibiotic resistance are highlighted. Thus, effective strategies in these areas are strongly recommended.
Key words: Antimicrobial agents; Drug resistance, Microbial; Gastrointestinal tract; Self-medication; Staphylococcus aureus; Nigeria
Staphylococcus aureus, the golden cluster seed, is a spherical bacterium frequently found in the nose, throat, intestine, vagina, and skin of human body (1). It is a pathogen of greater concern because of its ability to cause a diverse array of life-threatening infections and its capacity to adapt fast to the different environmental conditions (2,3). These features have made infections of S. aureus increasingly difficult to treat because of the fast rate at which it develops resistance to common antimicrobial agents.
Multiple antibiotic resistance is a major health concern in the treatment of staphylococcal infections, especially infections of methicillin-resistant S. aureus (MRSA) which occurs due to the extensive use of antimicrobial agents, coupled with the transmission of an appreciable proportion of the organism by person-to-person contacts (4). Hence, effective control of antibiotic use and prevention of the transmission of these strains are essential to eradicate this infectious organism.
The gut is an important habitat of parasites and bacteria which can be transmitted through objects contaminated with faeces, indicating the importance of faecal-oral transmission in humans, which can lead to mild or severe diseases in susceptible individuals or when found in sterile sites of the body (5). The presence of staphylococci in stools has been recognized as an important pathogen responsible for antibiotic-associated diarrhoea in humans (6). Reports of recent studies are also implicating the gut as an important reservoir of antibiotic-resistant S. aureus strains (7,8).
Most studies on S. aureus have so far been conducted on samples from the nose and throat but only a very few detailed studies on its colonization of the gut have been reported. Thus, there is a need for more studies on S. aureus from the gut, as an important reservoir of multiple antibiotic-resistant bacterial strains, especially in developing countries where the control of antibiotic use is inadequate. We report here the prevalence of multidrug-resistant faecal S. aureus isolates from healthy inhabitants in Amassoma, Nigeria.
MATERIALS AND METHODS
In total, 120 subjects comprising an equal number of villagers and students of the Niger Delta University, Wilberforce Island, Amassoma, Bayelsa state, Nigeria, were randomly recruited into the study for three months from March 2009. …