Staphylococcus aureus Drug Resistance in Sinusitis Patients
In this study on Sinusitis patients, we obtained 45 strains of Staphylococcus aureus. Antibiotic pattern of Staphyloccus aureus showed that resistance to Quinolones was 21% and 33% towards ciprofloxacin andoflaxacin respectively. Resistance to cephalosporins was 50% to cefuroxime, 41% and 50% to cefaperazone and cefotaxime respectively. Least resistance was noticed against aminoglycosides viz. Amikacin 47% and Gentamicin 21%. Resistance to Ampicillin and amoxicillin was 60% and 64% respectively. Oxacillin resistance was seen in 26% of the strains. Of the 45 isolates, 6 were found to be resistant for oxacillin . All these six isolates were subjected to Polymerase Chain Reaction (PCR) and they possessed the mecA gene. Correlation existed between the presence of mecA gene and oxacillin resistance in Staphylococcus aureus and these strains can be considered as MRSA and the patients can be advised for vancomycin therapy. Oxacillin resistance determination by phenotypic methods takes 24 hours to infer whereas PCR for mecA gene took only 6 hours. So the PCR techniques for the detection of mecA gene can be considered as gold standard (Rapid, Quick and accurate diagnosis) method for the detection of MRSA in spite of the cost involved.
Sinusitis is defined as inflammation of one or more of the paranasal sinuses caused by bacterial or viral infection; air-filled cavities in facial bones lined with pseudo stratified ciliated columnar epithelium and mucous goblet cells (Nord et al., 1995). There are several paired paranasal sinuses, including the frontal, ethmoid, maxillary and sphenoid sinuses. Maxillary sinuses are located behind the check bones and inflammation causes pain or pressure in the cheek (maxillary) area. They are present at birth and continue to develop as long as teeth erupt. Tooth roots in some cases, can penetrate the floor of these sinuses. Frontal sinuses are located on both sides of the forehead and inflammation causes pain or pressure in the frontal sinus cavity. These sinuses are late in developing and so infection here is uncommon in children (Orobello et al., 1991). Ethmoid sinuses are located between the eyes and inflammation causes pain or pressure pain between eyes. They resemble a honeycomb and are vulnerable to obstruction. Sphenoid sinuses are located behind the eye and inflammation causes pain or pressure behind the eyes, but often refers to the vertex of the head. They are usually present at the age of 3 and are fully developed at the age of 12 (Nord et al., 1995).
The symptoms are generally the same in both acute and chronic rhinosinusitis. The symptoms include-nasal symptoms (facial congestion, facial pain-pressure fullness and headache), Oropharyngeal symptoms (halistosis, dental pain, cough and ear pain, pressure fullness) and, systematic symptoms (fever and fatigue). The symptoms in single or combine occur. Acute and chronic sinusitis may be accompanied by thick purulent nasal discharge (usually green in colour, with or without blood) and localized headache (toothache) are present and it is these symptoms that can differentiate sinus related (or rhinogenic) headache from other headache phenomena such as tension headache and migraine headache (Salord et al., 1990).
It is important to diagnose nasal complaints accurately, because sinusitis requires antibiotics for rapid resolution. Untreated sinusitis can lead to serious and possibly life threatening complications. The clinical diagnosis of sinusitis is difficult because of the overlap in the symptoms of rhinitis and sinusitis.
Several studies in adults have shown a good correlation between cultures of the middle meatus and the sinus aspirates in patients with acute sinusitis, especially when purulence is seen in the middle meatus (Walder et al., 1981). In many geographic areas, amoxicillin is a reasonable first-line antibiotic. Although trimethoprim- sulfamethoxazole and erythromycin- sulfisoxazole have traditionally been used as first line antibiotic for patients with acute bacterial sinusitis, surveillance studies indicate the development of significant pneumococcal resistance from alteration of penicillin binding proteins. Erythromycin alone provides unsatisfactory coverage and is effective against β -lactamase producing organisms. When first line agents have failed or there is a high prevalence of β–lactamase resistance, amoxicillin or clavulanate or second or third-generation cephalosporins (e.g., cefuroxime, cefpodoxime, cefprozil) provide broader coverage. First-generation cephalosoprins (eg-cephalexin) and second generation cephalosporins (eg, cefaclor) provide improved coverage. Several quinolones (eg, ciprofloxacin, gatifloxacin, levofloxacin, moxifloxacin) have specific indications for the treatment of sinusitis, but these should be reserved for second or third time use or for more serious infections.
MRSA stands for methicillin resistant Staphylococcus aureus and also multi-resistant Staphylococcus aureus. S. aureus strains which are resistant to the normal antibiotics were successfully treated with Vancomycin (Mark et al., 2002). This is one of the antibiotics used to treat emerging multi-resistant organisms. It has evolved an ability to survive treatment with beta-lactamase resistant beta-lactam antibiotics, including methicillin, dicloxacillin, nafcillin, and oxacillin. MRSA is especially troublesome in hospital-associated (nosocomial) infections. The methicillin resistance gene (mecA) encodes a methicillin resistant penicillin-binding protein that is not present in susceptible strains and is believed to have been acquired from a distantly related species. mecA is carried on a mobile genetic element. Many MRSA isolates are multiply resistant and are susceptible only to glycopeptide antibiotics such as Vancomycin and other investigational drugs (Mark et al., 2002). MRSA isolates have decreased susceptibility to glycopeptides. DNA fragments of mecA gene derived from MRSA are used as a probe and this has been reported to be a means of identifying methicillin resistance. More recently, several attempts to detect the presence of the mecA gene by the Polymerase Chain Reaction (PCR) have also been reported (Araj et al., 1991)
The widespread emergence of methicillin resistant Staphylococcus aureus (MRSA), especially in various types of nosocomial infections, is a serious clinical problem worldwide. The incidence of methicillin resistance among nosocomial isolates of S. aureus is higher than 70% in some Asian countries such as Taiwan, China, and Korea. Recently, MRSA has also emerged in the community setting in some countries, including Asian countries (Duong,D et al.,). One of the cardinal features of the rapid emergence of MRSA in many parts of the world is the dissemination of specific clones; this has contributed to the accelerated increases in the incidence of MRSA. Therefore, it is important to investigate the genotypic characteristics and evolutionary pathway of MRSA clones as well as the genetic relatedness of the strains isolated in different geographic regions.
The aim of the present work is to evaluate the Antimocrobial activity of Staphylococcus aureus from sinusitis patients with respect to different antibiotics and to detect the Methicillin Resistant Staphylococcus aureus (MRSA) using genotypic method, rather using a phenotypic method. So the PCR techniques for the detection of mecA gene can be considered as gold standard (genotypic method). Accordingly, we disclose that mecA gene carrying Staphylococcus aureus were considered as MRSA and the patients who carry MRSA were advised to take Vancomycin therapy rather going with other antibiotics.
Source : Staphylococcus aureus Drug Resistance in Sinusitis Patients | InformativeBD
