Molecular characterization of methicillin-resistant Staphylococcus aureus isolates from a hospital in Ghana

Background: Methicillin-resistant Staphylococcus aureus (MRSA) are a major cause of hospital- and community-acquired infection. They can colonize humans and cause a wide range of infections including pneumonia, endocarditis and bacteraemia. We investigated the molecular mechanism of resistance and virulence of MRSA isolates from a teaching hospital in Ghana. Methodology: A total of 91 S. aureus isolates constituted the initial bacterial sample. Identification of S. aureus was confirmed by the VITEK 2 system. The cefoxitin screen test was used to detect MRSA and antibiotic susceptibility was determined using the VITEK 2 system. The resistance (mecA, blaZ, aac-aph, ermC, and tetK) and virulence (lukS/F-PV, hla, hld and eta) genes were amplified by polymerase chain reaction (PCR) and positive samples subjected to DNA sequencing. Pulsed field gel electrophoresis (PFGE) was used to ascertain the relatedness of the isolates. Results: Fifty-eight of 91 (63.7%) isolates were putatively methicillin resistant by the phenotypic cefoxitin screen test and oxacillin MICs. However, 43 (47%) of the isolates were genotypically confirmed as MRSA based on PCR detection of the mecA gene. Furthermore, 37.9% of isolates displayed resistance to tetracycline, 19% to trimethoprim-sulphamethoxazole, 15.5% to clindamycin, 12.1% to gentamicin, 13.8% to ciprofloxacin and erythromycin, 6.9% to moxifloxacin and 7.0% to rifampicin. None of the isolates was positive for inducible clindamycin resistance. The prevalence of resistance (mecA, blaZ, aac(6')-aph(2''), tetK, and ermC) and virulence (hla and lukS/F-PV) genes respectively were 74%, 33%, 22%, 19%, 3%, 5% and 3%, with isolates organized in two highly related clades. Conclusion: Results indicate a fairly high occurrence of MRSA, which can complicate the effective therapy of S. aureus infections, necessitating surveillance and stringent infection control programmes to forestall its spread

Molecular Genotyping of Methicillin Resistant and Susceptible Staphylococcus Aureus by Coagulase Gene Polymorphism

Background: Methicillin-resistant Staphylococcus aureus (MRSA) which causes nosocomial infections is among the most important multi-resistant pathogens worldwide. Investigations of MRSA outbreaks in nosocomial settings often require strain-typing data to verify effectively that the isolates belong to the outbreak strain; and to discriminate similarity from unsimilarity strains. Quick and reliable typing methods are required to obtain information among MRSA isolates and to allow faster implementation of appropriate control measures. Objective : The aim of this study was to investigate genotyping of methicillin resistant and sensitive Staphylococcus aureus (MRSA and MSSA) in Khartoum Teaching Hospital; Sudan by using antibiotype and polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP) of the coagulase gene. Methods: This is across sectional study. The samples were collected from clinical wound specimens in the wards of surgery; orthopaedic and burns at Khartoum Teaching Hospital; then processed; cultured and subsequently susceptibility test was performed using disc diffusion method. The MRSA strains were investigated by oxacillin 1[g disk diffusion method. PCR used to amplify a sequence of the coagulase (coa) gene; and the PCR products were analyzed by PCR-RFLP using Alu1 restriction enzyme. Result: Forty eight S. aureus strains were isolated and the number of MRSA identified was 9(18.75). All strains of MRSA and MSSA were sensitive to vancomycin; while multi-drug resistance was common among MRSA strains. PCR amplification products of coa gene were approximately at 500 bp (26/48); and 580 bp (22/48). By Alu1 restriction enzyme digestion of the PCR-amplified of coagulase gene; two distinct PCR-RFLP patterns exhibited; coaA and coaB and their fragments were approximately at 190; 310 bp and 190; 390 bp with percentages of 54.2(26/48) and 45.8(22/48) respectively. Conclusion: PCR-RFLP is considered an attractive tool for rapidly demonstrate the frequency of different patterns and discriminate the relatedness of isolates in different hospital wards

Methicillin Resistance in Staphylococcus aureus: a Review of the Molecular Epidemiology; Clinical Significance and Laboratory Detection Methods

BACKGROUND: Despite the volume of knowledge; enhanced surveillance and infection control measures adopted by health care institutions to address the endemicity and frequent disease outbreaks by methicillin-resistant Staphylococcus aureus (MRSA) in hospitals and health care facilities worldwide; infections due to this organism are still responsible for about 50of hospital acquired S. aureus infections; with increasing morbidity and mortality. OBJECTIVE: To provide regional clinicians with current information on the molecular epidemiology; laboratory detection and clinical aspects of MRSA. METHODS: A review of published literatures on MRSA in Medical Libraries and bibliographic citations on PubMed; Medline and Africa Index Medicus on molecular epidemiology and clinical diseases caused by MRSA and the assessment of the recent laboratory diagnostic approaches. RESULTS: This review showed that there has been intercontinental spread of some highly pathogenic clones of MRSA threatening to create public health hazard of unprecedented proportion; with the greatest challenge to mankind; being the development of resistance to multiple antibiotics; which in recent times had included resistance to vancomycin and other glycopeptides; the only antibiotic group effective against it. Added to this burden is the emergence of more virulent strains of community-associated MRSA (CAMRSA) which at the turn of the century; has been increasingly reported to cause infections and outbreaks in populations without predisposing risk factors; with attendant high morbidity and mortality. CONCLUSION: There is need for active MRSA surveillance by healthcare institutions in Africa to identify potential outbreaks; and vigilance in the enforcement of infection control measures such as rational prescription of antibiotics; handwashing; disinfection and sterilization that can limit the emergence and spread of more resistant clones of MRSA

Antibiotic-Resistant Staphylococcus aureus Isolated from Milk in the Mafikeng Area; North West Province; South Africa

The aim of this study was to isolate Staphylococcus aureus from samples of cow's milk obtained from different farm settings and to determine their antibiotic susceptibility patterns. Gram staining; oxidase; catalase; DNase; haemolysis and the MASTASTAPHTM rapid agglutination tests were employed for bacterial identification. A total of 28 milk samples were collected and screened for the presence of S. aureus. All the samples were contaminated with S. aureus. A total of 240 S. aureus isolates were obtained during this study. The levels of contamination with S. aureus were higher in milk obtained from the communal farms in Lokaleng and Mogosane (24.6and 35.4; respectively)compared to the commercial farms in Rooigrond and Molelwane (17.9and 22.1; respectively). A large percentage of the S. aureus isolates (39-100) from both communal farms was resistant to methicillin (MT); ampicillin (AP); penicillin G (PG); sulphamethoxazole (Smx); oxytetracycline (OT); erythromycin (E); nitrofurantoin (NI) and streptomycin (S); but not vancomycin (V). An even higher percentage (64.2- 100) of the isolates from both commercial farms was resistant to sulphamethoxazole and nitrofurantoin. A comparably smaller percentage (3.4- 4.7) of the isolates from both communal farms was resistant to vancomycin; but all isolates from commercial farm milk were susceptible to this drug. The predominant multiple antibiotic resistant phenotypes for isolates from the commercial farms were AP-Smx-NI and MT-AP-PG-OT-Smx-NI for Rooigrond and Molelwane farms; respectively; while those for isolates from the communal farms were MT-AP-PG-Smx-E-NI-S and MT-AP-PG-OT-Smx-NI-S for Lokaleng and Mogosane; respectively. When comparing the percentage of antibiotic resistance; a significant positive correlation was observed between the isolates from the commercial farms (r = 0.966; p 0.01). S. aureus is normally resident in humans; therefore; the S. aureus present in the cows may have resulted from transmission between the two species; emphasising the need to improve sanitary conditions in the milking environment

Prevalence and antimicrobial susceptibility pattern of methicillin resistant Staphylococcus aureus from healthcare and community associated sources

Methicillin resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen. We report the prevalence and antibiotic susceptibility pattern of MRSA in Amravati; Maharashtra state (India). A total of 150 healthcare-associated (HA) sources (doctors mobiles phone and wound/pus swabs); and 160 community-associated (CA) sources (hand swab) were screened for MRSA and their antibiotic resistance pattern was performed. Out of 41 isolated strains of S. aureus; 77from HA and 50CA samples were found to be methicillin resistant. There were high prevalence of MRSA in doctor's mobile phone (83) and wound/pus (71) (HA sources) than the hand swab. Almost all HA and CA MRSA strains were resistant to penicillin and penicillin V (100) followed by cloxacillin and cephalexin; co-trimoxazole. About 56 - 67HA and CA-MRSA strains were resistance to erythromycin; ceftazidime; lincomycin; ceftazidime; cephalexin; erythromycin and tetracycline indicating high degree of multi-resistance MRSA prevalence in the region. However; 67strains of CA and 56strains of HA were sensitive to vancomycin. The study showed high prevalence of MRSA in hospital setting indicating need of good control measures such as proper hand hygiene; avoiding mobile phone while wound dressing and treating patient; surveillance cultures and monitoring of susceptibility patterns of MRSA may also help in arresting the spread of infections in this part of India

Control of spread of Methicillin Resistant Staphylococcus aureus (MRSA) in Burns Units

Results of four years' studies from a number of hospitals in Kenya have shown that nosocomial infections in burns units are due to Methicillin Resistant Staphylococcus aureus (MRSA). Through chromosomal DNA and plasmid DNA; the stain is highly resistant to sulphonamide ointment and other antibiotics. 90 per cent of patients admitted in burns units get colonized or infected with MRSA. The strain prolongs the duration of patients in hospitals. The burns degenerate to second and third degree burns; thereby necessitating skin grafting. The environment has been found to be contaminated with this strain with some staff members having chronic throat infections. Minocycline was found to be effective in treating the infected staff members. Cleaning this environment with Sodium dichloroisocyanurate (precepts)/Sodium hypochlorite (JIK) reduced drastically the mechanical transmission of bacteria in the units. The duration of stay of the patient was reduced. This shows that MRSA which is spread in government and private hospitals can cheaply be controlled by the proper use of disinfectants; antiseptics; and use of effective antibiotics when necessary