AI-based predictive approach via FFB propagation in a driven-cavity of Ostwald de-Waele fluid using CFD-ANN and Levenberg-Marquardt.

The integration of Artificial Intelligence (AI) and Machine Learning (ML) techniques into computational science has ushered in a new era of innovation and efficiency in various fields, with particular significance in computational fluid dynamics (CFD). Several methods based on AI and Machine Learning (ML) have been standardized in many fields of computational science, including computational fluid dynamics (CFD). This study aims to couple CFD with artificial neural networks (ANNs) to predict the fluid forces that arise when a flowing fluid interacts with obstacles installed in the flow domain. The momentum equation elucidating the flow has been simulated by adopting the finite element method (FEM) for a range of rheological and kinematic conditions. Hydrodynamic forces, including pressure drop between the back and front of the obstacle, surface drag, and lift variations, are measured on the outer surface of the cylinder via CFD simulations. This data has subsequently been fed into a Feed-Forward Back (FFB) propagation neural network for the prediction of such forces with completely unknown data. For all cases, higher predictivity is achieved for the drag coefficient (CD) and lift coefficient (CL) since the mean square error (MSE) is within ± 2% and the coefficient of determination (R) is approximately 99% for all the cases. The influence of pertinent parameters like the power law index (n) and Reynolds number (Re) on velocity, pressure, and drag and lift coefficients is also presented for limited cases. Moreover, a significant reduction in computing time has been noticed while applying hybrid CFD-ANN approach as compared with CFD simulations only.

Characterization of aminoglycoside resistance genes in multidrug-resistant Klebsiella pneumoniae collected from tertiary hospitals during the COVID-19 pandemic.

Since the peak of the coronavirus disease 2019 (COVID-19) pandemic, concerns around multidrug-resistant (MDR) bacterial pathogens have increased. This study aimed to characterize aminoglycoside resistance genes in MDR Klebsiella pneumoniae (K. pneumoniae) collected during the COVID-19 pandemic. A total of 220 clinical isolates of gram-negative bacteria were collected from tertiary hospitals in Makkah, Saudi Arabia, between April 2020 and January 2021. The prevalence of K. pneumoniae was 40.5%; of the 89 K. pneumoniae isolates, MDR patterns were found among 51 (57.3%) strains. The MDR isolates showed elevated resistance rates to aminoglycoside agents, including amikacin (100%), gentamicin (98%), and tobramycin (98%). PCR assays detected one or more aminoglycoside genes in 42 (82.3%) MDR K. pneumoniae strains. The rmtD gene was the most predominant gene (66.7%; 34/51), followed by aac(6')-Ib and aph(3')-Ia (45.1%; 23/51). The aac(3)-II gene was the least frequent gene (7.8%; 4/51) produced by our isolates. The rmtC gene was not detected in the studied isolates. Our findings indicated a high risk of MDR bacterial infections through the COVID-19 outbreak. Therefore, there is a need for continuous implementation of effective infection prevention control (IPC) measures to monitor the occurrence of MDR pathogens and the emergence of MDR bacterial infections through the COVID-19 outbreak.

Epidemiological Features of COVID-19 in Makkah City: A Retrospective Data Analysis.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is continuing to circulate and change, affecting billions of people worldwide and leading to increased mortality rates, especially in the Holy City of Makkah, Kingdom of Saudi Arabia (KSA). This study was aimed at investigating the epidemiological features of COVID-19 in Makkah City, KSA. METHODS: A retrospective analysis was conducted to investigate the prevalence of COVID-19 and the association between the severity and mortality of COVID-19 with demographic factors and comorbidities. RESULTS: Among 4,742 COVID-19 patients, the incidence rate observed in males was 66.7%, and 69.7% were from Al-Noor Specialized Hospital. The highest incidence rate (25.2%) was found in the age group > 60 years old, followed by the age group 51-60 years (21.8%). Furthermore, the highest frequency was observed in patients from Saudi Arabia (36.8%), followed by patients from Myanmar (14.7%) and Bangladesh (9.4%). The overall frequency of COVID-19 severity and death was 20.3% and 11.6%, respectively. Body mass index analysis showed that 1% of the patients were underweight, while 9.2% were overweight and 4.4% were obese. In addition, 9.6% had diabetes, 6.9% had hypertension, 1.1% had heart disease, and 2.2% had other chronic diseases. CONCLUSION: The study concluded that the overall percentages of severe COVID-19 (intensive care unit) cases and deaths in Makkah City, KSA, were 20.3% and 11.6%, respectively, and there was a higher incidence in male patients. The severity of infection was shown to have a strong significant correlation with different chronic diseases, nationality, body mass index, death rate (mortality), heart disease, and length of hospital stay (P < 0.05). Despite these findings, more studies are needed to explain the underlying mechanisms that influence the overall health status of patients with specific characteristics and comorbidities.

The Influence of Different Plasma Cell Discharges on the Performance Quality of Surgical Gown Samples.

An experimental study was performed on a low-density plasma discharge using two different configurations of the plasma cell cathode, namely, the one mesh system electrodes (OMSE) and the one mesh and three system electrodes (OMTSE), to determine the electrical characteristics of the plasma such as current-voltage characteristics, breakdown voltage (VB), Paschen curves, current density (J), cathode fall thickness (dc), and electron density of the treated sample. The influence of the electrical characteristics of the plasma fluid in the cathode fall region for different cathode configuration cells (OMSE and OMTSE) on the performance quality of a surgical gown was studied to determine surface modification, treatment efficiency, exposure time, wettability property, and mechanical properties. Over a very short exposure time, the treatment efficiency for the surgical gown surface of plasma over the mesh cathode at a distance equivalent to the cathode fall distance dc values of the OMTSE and for OMSE reached a maximum. The wettability property decreased from 90 to 40% for OMTSE over a 180 s exposure time and decreased from 90 to 10% for OMSE over a 160 s exposure time. The mechanisms of each stage of surgical gown treatment by plasma are described. In this study, the mechanical properties of the untreated and treated surgical gown samples such as the tensile strength and elongation percentage, ultimate tensile strength, yield strength, strain hardening, resilience, toughness, and fracture (breaking) point were studied. Plasma had a more positive effect on the mechanical properties of the OMSE reactor than those of the OMTSE reactor.

Increasing frequency of Aminoglycoside-Resistant Klebsiella pneumoniae during the era of pandemic COVID-19.

The emergence of multidrug resistance to aminoglycosides in K. pneumoniae isolates is a growing concern, especially during pandemic Coronavirus disease 2019 (COVID-19). The study identifies antibiotic resistance in K. pneumoniae isolated from tertiary hospitals during pandemic COVID-19. Among 220 clinical isolates, the total rate of K. pneumoniae was found to be 89 (40.5%). Phenotyping results confirmed the resistance of aminoglycoside antibiotics in 51 (23.2%) of K. pneumoniae isolates. PCR results confirmed the existence of one or more aminoglycoside genes in 82.3% of the 51 isolates. The rmtD gene was the highest-detected gene (66.7%), followed by aac(6')-Ib (45.1%), aph(3')-Ia (45.1%), rmtB (29.4%), armA (21.6%), aac(3)-II (7.8%), and rmtA (3) (11.8%). Significantly, higher resistance strains showed a higher prevalence (61.5%) of aminoglycoside genes (p < 0.05). During COVID-19, there is a higher risk of acquiring MDR bacterial infections, so the monitoring of multidrug resistant bacteria must be continuously undertaken to implement effective measures in infection control and prevention.

Inactivation of E. coli Using Atmospheric Pressure Plasma Jet with Dry and Wet Argon Discharges.

The acceleration of inactivating viable cells of Escherichia coli (E. coli), by using new direct and indirect innovative methods, is the targeted method of using an atmospheric pressure plasma jet (APPJ) operated by an AC high-voltage power source with variable frequency up to 60 kHz and voltage ranging from 2.5 to 25 kV. Discharges using dry argon (0% O2) discharges and different wet argon discharges using admixtures with O2/Ar ratios ranging from 0.25% to 1.5% were studied. The combined effects of dry and wet argon discharges, direct and indirect exposure using a mesh controller, and hollow magnets were studied to reach a complete bacterial inactivation in short application times. Survival curves showed that the inactivation rate increased as the wettability increased. The application of magnetized non-thermal plasma discharge with a 1.5% wetness ratio causes a fast inactivation rate of microbes on surfaces, and a dramatic decrease of the residual survival of the bacterial ratio due to an increase in the jet width and the enhanced ability of fast transport of the charges to viable cells, especially at the edge of the Petri dish. The membrane damage of E. coli mechanism factors in the activation process by APPJ is discussed.

Influenza vaccination among Saudi Hajj pilgrims: Revealing the uptake and vaccination barriers.

BACKGROUND: Hajj is the world's largest annual mass gathering that attracts two to three million Muslims from around the globe to a religious assemblage in Makkah, Saudi Arabia. The risk of acquisition and transmission of influenza among Hajj pilgrims is high. Therefore, influenza vaccination is recommended, and was monitored frequently among pilgrims from different countries. However, the vaccination uptake among Saudi pilgrims has not been assessed in recent years. OBJECTIVE: This analysis aims to evaluate influenza vaccine uptake among Saudi Hajj pilgrims, and identify the key barriers to vaccination. METHOD: Data on influenza vaccination were obtained from Saudi pilgrims who took part in a large trial during the Hajj of 2013, 2014 and 2015. Pilgrims were met and recruited in Mina, Makkah during the peak period of Hajj and were asked to complete a baseline questionnaire that recorded their influenza vaccination history, including reason(s) for non-receipt of vaccine. RESULTS: A total of 6974 Saudi pilgrims aged between 18 and 95 (median 34) years were recruited; male to female ratio was 1:1.2. Of the total, 90.8% declared their influenza vaccination history, 51.3% of them reported receiving influenza vaccine before travel to Hajj. The vaccination rates for the years 2013, 2014 and 2015 were 21.4%, 48.2% and 58.1%, respectively (P < 0.001). Of 1,269 pilgrims who were at higher risk of severe disease, 54.5% received the vaccine. Lack of awareness (47.5%), reliance on natural immunity (15.8%) and being busy (15.5%) were the main reasons for non-receipt. CONCLUSION: These data from a convenience sample indicate that influenza vaccine uptake among Saudi Hajj pilgrims is increasing over years but still needs further improvement. Lack of awareness and misperceptions are the main barriers. Education of Saudi pilgrims and health professionals is required to raise awareness about influenza vaccination. Further studies are needed to understand pilgrims' misperceptions.

An efficient system for the generation of marked genetic mutants in members of the genus Burkholderia.

To elucidate the function of a gene in bacteria it is vital that targeted gene inactivation (allelic replacement) can be achieved. Allelic replacement is often carried out by disruption of the gene of interest by insertion of an antibiotic-resistance marker followed by subsequent transfer of the mutant allele to the genome of the host organism in place of the wild-type gene. However, due to their intrinsic resistance to many antibiotics only selected antibiotic-resistance markers can be used in members of the genus Burkholderia, including the Burkholderia cepacia complex (Bcc). Here we describe the construction of improved antibiotic-resistance cassettes that specify resistance to kanamycin, chloramphenicol or trimethoprim effectively in the Bcc and related species. These were then used in combination with and/or to construct a series enhanced suicide vectors, pSHAFT2, pSHAFT3 and pSHAFT-GFP to facilitate effective allelic replacement in the Bcc. Validation of these improved suicide vectors was demonstrated by the genetic inactivation of selected genes in the Bcc species Burkholderia cenocepacia and B. lata, and in the non-Bcc species, B. thailandensis.

Viral respiratory infections among Hajj pilgrims in 2013.

Middle East respiratory syndrome coronavirus (MERS-CoV) has emerged in the Arabian Gulf region, with its epicentre in Saudi Arabia, the host of the 'Hajj' which is the world's the largest mass gathering. Transmission of MERS-CoV at such an event could lead to its rapid worldwide dissemination. Therefore, we studied the frequency of viruses causing influenza-like illnesses (ILI) among participants in a randomised controlled trial at the Hajj 2013. We recruited 1038 pilgrims from Saudi Arabia, Australia and Qatar during the first day of Hajj and followed them closely for four days. A nasal swab was collected from each pilgrim who developed ILI. Respiratory viruses were detected using multiplex RT-PCR. ILI occurred in 112/1038 (11%) pilgrims. Their mean age was 35 years, 49 (44%) were male and 35 (31%) had received the influenza vaccine pre-Hajj. Forty two (38%) pilgrims had laboratory-confirmed viral infections; 28 (25%) rhinovirus, 5 (4%) influenza A, 2 (2%) adenovirus, 2 (2%) human coronavirus OC43/229E, 2 (2%) parainfluenza virus 3, 1 (1%) parainfluenza virus 1, and 2 (2%) dual infections. No MERS-CoV was detected in any sample. Rhinovirus was the commonest cause of ILI among Hajj pilgrims in 2013. Infection control and appropriate vaccination are necessary to prevent transmission of respiratory viruses at Hajj and other mass gatherings.

Demographic distribution and transmission potential of influenza A and 2009 pandemic influenza A H1N1 in pilgrims.

INTRODUCTION: The World Health Organization's persistent reporting of global outbreaks of influenza A viruses, including the 2009 pandemic swine A H1N1 strain (H1N1pdm09), justified the targeted surveillance of pilgrims during their annual congregation that pools more than two million people from around 165 nations in a confined area of Makkah city in the Kingdom of Saudi Arabia (KSA). METHODOLOGY: A total of 1,600 pilgrims were included in the targeted surveillance of influenza A and the 2009 pandemic swine H1N1 strain in the Hajj (pilgrimage) season of 2010. Each pilgrim responded to a demographic and health questionnaire. Collected oropharyngeal swabs were analyzed by real-time PCR for influenza A viruses, and positive samples were further analyzed for the presence of H1N1pdm09. Fisher's exact test was applied in the analysis of the significance of the distribution of influenza-positive pilgrims according to demographic characters. RESULTS: A total of 120 pilgrims (7.5%) tested positive for influenza A viruses by real-time PCR. Nine out of the 120 influenza-A-positive pilgrims (7.5%) were positive for H1N1pdm09. Demographics played a significant role in those pilgrims who tested positive for influenza A. CONCLUSIONS: The detection of H1N1pdm09 in pilgrims at their port of entry to the KSA was alarming, due to the high potential of trans-boundary transmission. This situation necessitates the implementation of specific prevention and control programs to limit infection by influenza A viruses.

Molecular characterization of methicillin-resistant Staphylococcus aureus isolated from tertiary care hospitals.

BACKGROUND AND OBJECTIVES: Methicillin-resistant S. aureus (MRSA) tends to be resistant to multiple antibiotics. Methicillin resistance is conferred by the acquisition of the mecA gene, which is carried by a mobile genetic element called the staphylococcal cassette chromosome mec (SCCmec). There are five major types of SCCmec elements (I-V). The majority of hospital-acquired MRSA (HA-MRSA) strains carry SCCmec types I, II, or III, whereas community-acquired MRSA (CA-MRSA) strains carry SCCmec types IV or V. In addition, Panton-Valentine Leucocidin (PVL) is a gene encoding a powerful cytotoxin that is strongly associated with CA-MRSA strains. The present study was aimed to identify the types of SCCmec and PVL genes among clinical MRSA isolates. METHODS: This study was conducted in 5 tertiary care hospitals in Makkah city from March to September of 2012. A total of 206 S. aureus clinical isolates were analysed using standard microbiological methods. Multiplex PCR was performed on genomic DNA from MRSA isolates in order to identify the types of SCCmec. In addition, PCR was performed to detect the PVL gene among the isolates. RESULTS: Of the 206 S. aureus isolates, 114 (55.3%) were MRSA, and 100 of the MRSA isolates carried the mecA gene. RESULTS from SCCmec typing revealed that 3% were type I; 9% were type II; 47% were type III, and 29% were type IV. Nineteen per cent of the isolates harboured the PVL gene. Furthermore, there was a statistically significant correlation between the presence of the PVL gene and SCCmec type IV. CONCLUSION: The virulence of MRSA strains is increasing in both hospital and community settings in Makkah, highlighting the importance of their rapid identification in order to appropriately control infection.

Pneumococcal Vaccine Uptake Among Australian Hajj Pilgrims in 2011-13.

The uptake of the pneumococcal vaccine is suboptimal in Australia and remains unknown among Australian Hajj pilgrims, many of whom are eligible because of age or underlying disease and at particular risk because of travel and activities at Hajj. Pneumococcal vaccination uptake was examined over three consecutive years (2011 to 2013) through anonymous self-administered cross sectional surveys among Australian pilgrims who assembled in Mina valley, Mecca, Saudi Arabia. Respectively, 158, 513 and 219 pilgrims were recruited in 2011, 2012 and 2013; their mean ages were 43.8 (SD±13), 43 (SD±13.5) and 42.6 (SD±12.3) years; males accounted for 67 (42.4%), 325 (63.4%) and 172 (78.5%). Pneumococcal vaccine uptake rates were 28.5% (45/158), 28.7% (147/513) and 14.2% (31/219); among the pilgrims with 'at risk' conditions the pneumococcal vaccine uptake rates were 15 (30.6%), 43 (45.3%) and 9 (29%) respectively. According to our surveys, the pneumococcal vaccine uptake among Australian pilgrims is low. Further research is needed to explore the reasons through a validated study.

Frequency and antibiotic susceptibility of gram-positive bacteria in Makkah hospitals.

BACKGROUND AND OBJECTIVE: Gram-positive bacteria are important nosocomial pathogens. The objective of this study was to estimate the frequencies and resistance rates of gram-positive pathogens isolated from hospitals in Makkah, Saudi Arabia. DESIGN AND SETTING: Prospective study at three Makkah hospitals from May 2008 to April 2009. PATIENTS AND METHODS: Clinical isolates were collected and demographic and laboratory data were recorded. Standard microbiological methods were used to identify the organisms and test for antimicrobial susceptibility. The results were interpreted according to the Clinical Laboratory Standards Institute (CLSI) guidelines. RESULTS: Clinical isolates were collected from 1087 patients. Gram-positive pathogens infected all age groups, but had no gender predominance. Staphylococcus aureus was the most common cause of wound infection and accounted for more than half of the clinical isolates (688 cases). Coagulase-negative staphylococcus (CONS) was a common isolate from blood cultures. Wounds were the most common site of infection (37.6%). Enterococcus spp. and Streptococcus agalactiae were the second most common bacteria (26%). The resistance rates of S aureus and CONS isolates were 39.4% and 82.4% for oxacillin, respectively. Among the streptococci, the resistance rates of Streptococcus pneumoniae were 21.1% and 16.7% for ampicillin and erythromycin, respectively. CONCLUSIONS: S aureus infections were found to be very common in the Makkah hospitals. Infection prevention, control measures and continuous monitoring for antibiotic susceptibility are necessary to reduce these and other nosocomial infections.

Profile of bacterial pneumonia during Hajj.

BACKGROUND & OBJECTIVES: The congregation of a large number of people during Hajj seasons from different parts of the world in overcrowded conditions within a confined area for a long period of time presents many public health challenges and health risks. One of the main health problems of the crowding is ease transmission of pneumonia by air droplets. This study was aimed to determine the most common causes of bacterial pneumonia during the 2005 Hajj season and to relate the findings with clinical conditions. METHODS: A total of 141 patients with suspected pneumonia from the three main tertiary care hospitals in Makkah, Saudi Arabia, were investigated during Hajj season, 2005. Sputum and serum samples were collected and investigated for the possible presence of typical or atypical causative agents. RESULTS: Of the 141 clinically suspected pneumonia cases, 76 (53.9%) were confirmed positive by microbiological tests. More than 94 per cent of the confirmed cases were in the age group >50 yr, and 56.6 per cent of the cases were men. The most frequent isolates were Candida albicans (28.7%) and Pseudomonas aeruginosa (21.8%), followed by Legionella pneumophila (14.9%) and Klabsiella pneumoniae (9.2%). More than one causative pathogens were isolated in 15 patients (16.3%), and 55 per cent of patients were diabetic. INTERPRETATION & CONCLUSIONS: Clinicians should be aware that typical pneumonia treatment regimens may not work well during the Hajj season due to the wide variety of isolated organisms. This necessitates taking a sputum sample before starting treatment for identification and sensitivity testing. Special precautions need to be taken for >50 yr old patients.

The pobA gene of Burkholderia cenocepacia encodes a group I Sfp-type phosphopantetheinyltransferase required for biosynthesis of the siderophores ornibactin and pyochelin.

The opportunistic pathogen Burkholderia cenocepacia produces the siderophores ornibactin and pyochelin under iron-restricted conditions. Biosynthesis of both siderophores requires the involvement of non-ribosomal peptide synthetases (NRPSs). Using a transposon containing the lacZ reporter gene, two B. cenocepacia mutants were isolated which were deficient in siderophore production. Mutant IW10 was shown to produce normal amounts of ornibactin but only trace amounts of pyochelin, whereas synthesis of both siderophores was abolished in AHA27. Growth of AHA27, but not IW10, was inhibited under iron-restricted conditions. In both mutants, the transposon had integrated into the pobA gene, which encodes a polypeptide exhibiting similarity to the Sfp-type phosphopantetheinyltransferases (PPTases). These enzymes are responsible for activation of NRPSs by the covalent attachment of the 4'-phosphopantetheine (P-pant) moiety of coenzyme A. Previously characterized PPTase genes from other bacteria were shown to efficiently complement both mutants for siderophore production when provided in trans. The B. cenocepacia pobA gene was also able to efficiently complement an Escherichia coli entD mutant for production of the siderophore enterobactin. Using mutant IW10, in which the lacZ gene carried by the transposon is inserted in the same orientation as pobA, it was shown that pobA is not appreciably iron-regulated. Finally, we confirmed that Sfp-type bacterial PPTases can be subdivided into two distinct groups, and we present the amino acid signature sequences which characterize each of these groups.

Frequency and antimicrobial susceptibility of gram-negative bacteria isolated from 2 hospitals in Makkah, Saudi Arabia.

OBJECTIVE: To estimate the prevalence and antibiotic susceptibility of the gram-negative bacteria isolated from 2 hospitals in Makkah. METHODS: This study was undertaken in 2 main tertiary care hospitals namely; Al-Noor Specialist Hospital, and Hera Hospital in Makkah, Kingdom of Saudi Arabia from October 2005 to March 2006. A total of 1137 gram-negative bacteria were identified in non-duplicate clinical specimens obtained from 965 patients of various body sites infections. Demographic data, identity of microorganisms, and antimicrobial susceptibilities were obtained from medical and laboratory records. RESULTS: The most prevalent gram-negative bacteria were Escherichia coli (31.6%), and Pseudomonas aeruginosa (31.2%), followed by Acinetobacter baumannii (10.8%), Klebsiella pneumoniae (8.3%), Klebsiella sp. (6.2%), Haemophilus influenzae (3.7%), Proteus sp. (3.3%), and Enterobacter sp. (1.9%). Results demonstrated that gram-negative bacteria have a high rate of resistance to commonly used antibiotics. Furthermore, multi-drug resistance was also common in this study. CONCLUSION: Our data showed a high rate of resistance among gram-negative pathogens in comparison with other countries in the world. The implementation of monitoring programs is an important part of the prevention strategy against the development of antibiotic resistance in hospitals.

Frequency and antimicrobial susceptibility patterns of bacterial pathogens isolated from septicemic patients in Makkah hospitals.

OBJECTIVES: To determine the frequency of septicemic cases in Makkah hospitals, the main pathogens causing septicemia, and to describe the prevalence of antibiotic resistance among septicemia clinical isolates. METHODS: We performed a prospective study of 1626 septicemic cases in the 4 main hospitals in Makkah City during April 2004 to March 2005. Blood culture, isolation of organism and susceptibility to antibiotics were assessed using a routine microbiological methods. RESULTS: Out of the 1626 septicemic cases identified, gram-positive organisms were involved in 56.6% of these episodes with coagulase-negative Staphylococci and Staphylococcus aureus being the most frequent. While Escherichia coli and Pseudomonas species were the most common among gram-negative organisms. Candida species was involved in 5.9% of all encountered organisms. Most septicemic cases were reported in male patients over 50 years, the intensive care units, Saudi patients and during Hajj season. Results also showed the frequency and antimicrobial susceptibility patterns of bacterial pathogens isolated from septicemic patients in Makkah hospitals. CONCLUSION: The rates of antibiotic resistance among pathogens in this study, are much higher than what has been reported elsewhere in the Kingdom as well as in many of international studies.

Methicillin resistance among Staphylococcus aureus isolates from Saudi hospitals.

OBJECTIVE: To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) strains among clinical isolates collected from the 4 tertiary hospitals in Makkah, Saudi Arabia, and to test the antimicrobial susceptibility patterns of S. aureus isolates against 9 antimicrobial agents. MATERIALS AND METHODS: A total of 512 S. aureus clinical isolates were collected during a period of 1 year starting in April 2003 in Al-Noor, King Abdul-Aziz, Hera and King Faisal Hospitals, Makkah, Saudi Arabia. The sensitivity patterns of these isolates were determined using the Kirby-Bauer disk diffusion method. RESULTS: The prevalence of MRSA among S. aureus isolates was 38.9% (199/512). Among 199 MRSA isolates, 78.8% showed multidrug resistance to erythromycin, gentamicin and oxytetracycline. CONCLUSION: The rate of MRSA resistance in this study was much higher than what had been reported in other areas of Saudi Arabia emphasizing the need for local or country-based surveillance to characterize and monitor MRSA and to develop strategies that will improve MRSA treatment and control.