Prevalence of methicillin-resistant and methicillin-sensitive Staphylococcus aureus nasal colonization among patients at the time of admission to the hospital

Predictive Role of Targeted, Active Surveillance Cultures for Detection of Methicillin-Resistant Staphylococcus aureus

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) colonisation is an important source of healthcare-acquired infections. Reliable screening strategies for MRSA colonisation are essential for the timely implementation of infection control measures.

AIM

This study determined reliable MRSA screening sites to predict colonisation in resource-limited settings and estimated the impact of missed MRSA cases when shifting from multi- to single-site screening.

METHODOLOGY

A cross-sectional study was conducted in patients with positive MRSA surveillance cultures from the routinely screened sites (nasal, axillary, groin, and throat) from January 2009 to December 2019.

RESULTS

A total of 1906 screening tests were positive for MRSA cultures (n = 1345 patients). As a single site, the nasal cavity showed the highest MRSA detection, with a sensitivity of 66.8% (95% CI = 64-69) with 277.9 missed isolation days. Screening three or more anatomical sites detected 97-100% of MRSA cases, with 0-24.5 missed isolation days. Screening the axilla and groin separately or in combination showed a good clinical utility index (CUI) of >0.6 to <0.8, while an excellent CUI was obtained upon screening other site samples (>0.8). The combined nasal and throat cultures demonstrated a sensitivity of 93.2 (95% CI = 91-94) with 57.2 missed isolation days.

CONCLUSION

Multi-site screening is the optimal strategy for minimising MRSA exposure within a healthcare facility. For active MRSA surveillance, a combination of nasal and throat cultures can provide a practical approach in low-resource settings compared to nasal sampling alone.

Epidemiology of Methicillin-Resistant Staphylococcus Aureus in Arab Countries of the Middle East and North African (MENA) Region

Available data suggest a high burden of methicillin-resistant staphylococcus aureus (MRSA) in Arab countries of the Middle East and North Africa (MENA). To review the MRSA rates and molecular epidemiology in this region, we used PubMed search engine to identify relative articles published from January 2005 to December 2019. Great heterogeneity in reported rates was expectedly seen. Nasal MRSA colonization ranged from 2%–16% in Gulf Cooperation Council (GCC), 1–9% in the Levant, and 0.2%–9% in North African Arab states. Infective MRSA rates ranged from 9%–38% in GCC, 28%–67% in the Levant, and 28%–57% in North African states. Studies demonstrated a wide clonal diversity in the MENA. The most common molecular types belonged to 5 clonal complexes (CC) known to spread worldwide: CC5, CC8, CC22, CC30, and CC80. The most prevalent strains had genotypes related to the European community-acquired MRSA (CA-MRSA), Brazilian/Hungarian hospital-acquired MRSA (HA-MRSA), UK-EMRSA-15 HA-MRSA, and USA300 CA-MRSA. Finally, significant antimicrobial resistance was seen in the region with variation in patterns depending on location and clonal type. For a more accurate assessment of MRSA epidemiology and burden, the Arab countries need to implement national surveillance systems.

Phenotype-Genotype Characterization and Antibiotic-Resistance Correlations Among Colonizing and Infectious Methicillin-Resistant Staphylococcus aureus Recovered from Intensive Care Units

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) presents a profound hazard to public health. MRSA colonizing skin, mucous membranes, and the anterior nares without clinical symptoms is termed "colonizing MRSA". Upon manifestation of clinical symptoms, it is termed "infectious MRSA". Here, we characterize and differentiate colonizing and infectious MRSA, and analyze the phenotypic-genotypic and antibiotic susceptibility correlations.

Methodology

Clinical MRSA isolates were recovered from intensive care units (ICUs) of two major Egyptian hospitals and their biofilm formation ability was tested. Antibiograms against 16 antibiotics were determined, in addition to the minimum inhibitory concentrations (MICs) of vancomycin and linezolid. The entire collection was typed by enterobacterial repetitive intergenic consensus (ERIC)-PCR, as well as multi-locus sequence typing (MLST). Representative resistance and virulence genes were detected by PCR amplification.

Results

Forty-nine isolates were confirmed as MRSA, of which 30 isolates were infectious and 19 were colonizing. Versatile resistance patterns were observed in both groups of isolates. We report a higher tendency for biofilm-formation and borderline minimum inhibitory concentrations among infectious isolates. A Positive antibiotic correlation was observed between susceptibility to protein synthesis inhibitors and cell wall inhibitors. Positive correlations were observed between isolation site and rifampicin resistance: nasal samples were enriched in rifampicin-resistant isolates, while urine and blood samples were enriched in susceptible ones. Furthermore, biofilm formation ability was slightly associated with amikacin resistance, and an association between teicoplanin resistance and the presence of the Panton-Valentine leukocidin gene was the only significant phenotype-genotype correlation observed. Finally, ERIC typing and MLST had congruent results.

Conclusion

Linezolid and vancomycin are still the most convenient choice for MRSA treatment. ERIC PCR and MLST show promising typing combination that could be easily used periodically for tracking the genotypic changes of MRSA, especially within the healthcare facilities. Several correlations were established between groups of antibiotics and the genotypes/phenotypes of the selected isolates.

Genetic Lineages of Methicillin-Resistant Staphylococcus aureus Acquired during Admission to an Intensive Care Unit of a General Hospital

OBJECTIVES

The objectives of this study were to determine the frequency of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection while on admission to the intensive care unit (ICU), and examine the genetic backgrounds of the MRSA isolates to establish transmission among the patients.

SUBJECTS AND METHODS

This study involved screening 2,429 patients admitted to the ICU of Farwania Hospital from January 2005 to October 2007 for MRSA colonization or infection. The MRSA isolates acquired after admission were investigated using a combination of molecular typing techniques to determine their genetic backgrounds.

RESULTS

Of 2,429 patients screened, 25 (1.0%) acquired MRSA after admission to the ICU. Of the 25 MRSA, 19 (76%) isolates belonged to health care-associated (HA-MRSA) clones: ST239-III (n = 17, 68%) and ST22-IV (n = 2, 8%). The remaining 6 MRSA isolates belonged to community-associated clones: ST80-IV (n = 3, 12%), ST97-IV (n = 2, 8%), and ST5-IV (n = 1, 4%). The ST239-III-MRSA clone was associated with infection as well as colonization, and was isolated from patients from 2005 to 2007.

CONCLUSIONS

The HA-MRSA clone ST239-III persistently colonized patients admitted to the ICU, indicating the possibility of its transmission among the patients over time.

Methicillin-Resistant Staphylococcus aureus: A 5-Year Review of Surveillance Data in a Tertiary Care Hospital in Saudi Arabia

Background.

Staphylococcus aureus is an important pathogen that leads to serious infections in the community and in hospitals. Evidence has shown that the prevalence of infection and colonization with drug-resistant S. aureus, such as methicillin-resistant S. aureus (MRSA) and glycopeptide intermediately susceptible S. aureus, is increasing. Authorities must be aware of the prevalence of MRSA infection and colonization in their country in order to implement and monitor infection control policies that help curtail further emergence of this pathogen.

Objectives.

To examine the trend of hospital-acquired MRSA infection and colonization in a tertiary care institution in Saudi Arabia during a 5-year period in order to identify specific areas at high risk for MRSA transmission, and to review our MRSA decolonization procedure and outcomes.

Methods.

Surveillance data prospectively collected from January 1, 2000, through December 31, 2004, on hospital-acquired (HA) MRSA were analyzed, with an emphasis on the trend of HA-MRSA infection and colonization, areas of high transmission, risk factors, and effectiveness of the implemented decolonization policy.

Results.

During the study period, 442 cases of HA-MRSA infection and colonization were identified. Of these, 51.2% were infections, and 48.8% were colonizations. An increasing trend in the incidence rates of infection and colonization was noticed during the study period, and most cases were identified on the surgical ward (33.3%) and medical ward (32.1%). Of the 34 infected patients who underwent systematic decolonization, 35.3% were successfully decolonized, and of the 11 who underwent topical decolonization, 63.6% were successfully decolonized.

Conclusion.

The increasing trend of HA-MRSA infections has been a noticeable global problem. We identified a gradual increase in the rates of MRSA colonization and infection in a tertiary care center Saudi Arabia and recognize the importance of abiding by strict infection control policies, including hand hygiene and proper isolation practices. Continued surveillance for MRSA and other emerging multidrug-resistant pathogens is also needed.

Antimicrobial resistance among Gram-positive pathogens in Saudi Arabia

Several species of Gram-positive cocci are major nosocomial or community pathogens associated with morbidity and mortality. Here, we review the antimicrobial resistance among these pathogens in Saudi Arabia. In the last decades, antimicrobial resistance has increased among Staphylococcus aureus in the Kingdom with a growing prevalence of both nosocomial and community methicillin-resistant S. aureus (MRSA) isolates. As yet, no vancomycin-resistant MRSA have been reported, although isolates with reduced susceptibility to the drug have been noted. Currently, the prevalence of vancomycin-resistant entrococci (VRE) is low; however, VRE has been described in the Kingdom as well as Enterococcus faecalis and E. faecium isolates with high-level resistance to penicillin, sulfamethoxazole, macrolides, tetracycline, and aminoglycosides. In recent decades, the prevalence and rate of penicillin resistance and non-susceptibility among Streptococcus pneumoniae isolates have increased in Saudi Arabia. The organism remains, however, susceptible to other beta-lactams and to quinolones. On the other hand, resistance to co-trimoxazole and tetracyclines is high and resistance to macrolides is on the increase.

Staphylococcus aureus nasal carriage rate and associated risk factors in individuals in the community

The increasing prevalence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) strains together with their disease impact on hospital patients and individuals in the community has posed a major challenge to healthcare workers. This study examined the prevalence of S. aureus nasal carriage, antimicrobial susceptibility patterns, and possible risk factors in the community. Of 500 studied subjects (aged from 6 to 65 years) in Lebanon, the overall S. aureus nasal carriage rate was 38.4%, the highest (57.1%) being in children aged 6-10 years. Only eight individuals (1.6%) were carriers of MRSA. Risk factors for S. aureus nasal colonization were male gender, young age, contact with healthcare workers, use of needle injections, and having asthma. A significant decrease in colonization rate was associated with nasal wash with water, use of nasal sprays, and the presence of acne. These findings may assist in better understanding of control measures to decrease nasal colonization with S. aureus in Lebanon and elsewhere.

Evidence for cost reduction based on pre-admission MRSA screening in general surgery

Colonization with methicillin-resistant Staphylococcus aureus (MRSA) is a risk factor for MRSA infection causing increased costs in patient's care and treatment. To evaluate cost efficiency, pre-admission MRSA screening and subsequent MRSA decolonization of patients admitted to the Department of General Surgery at the University Hospital of Münster were determined. In 2004, 2054 (89.3%) out of the total of 2299 hospital-admitted patients were screened for MRSA (1769 elective and 530 direct admissions); 1536 patients underwent pre-admission MRSA screening (86.8% of the 1769 elective admissions), of whom seven patients (0.5%) were MRSA-positive and five of these were successfully decolonized before admission. In case of direct admissions, i.e., emergency cases or transferral from other hospitals, 2.4% and 8.6% were MRSA-positive, respectively. There were 25 patients MRSA positive during their hospital stay, two of these were nosocomially acquired, which represent 0.1 nosocomial MRSA cases in 1000 in-patients. The average MRSA carrier was (65+/-15 years) older than the other patients (55+/-17 years), had a significantly higher rate of pulmonary disease, coronary heart disease and certain infections; and had a longer hospital stay (27 versus 10 days, p<0.05). The total costs of the MRSA screening were approximately 20,000 euro. Since the estimated costs for handling MRSA treatment and isolation during a hospital stay are 6000-10,000 euro for each affected patient, we estimated that approximately 20,000 euro could be saved by detecting and successfully decolonizing a total of five patients through pre-admission screening. In this calculation, additional costs due to the increased morbidity and mortality of MRSA carriers and the possible spread of MRSA through unrecognized colonization were not included. In conclusion, pre-admission screening for MRSA is an effective method to reduce the hospital burden of MRSA-colonized patients and the savings due to consistent decolonization before elective admission outweigh the costs of screening.

Trends in antibiotic susceptibility patterns and epidemiology of MRSA isolates from several hospitals in Riyadh, Saudi Arabia

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA), is associated with high morbidity and mortality rates with rapid development of resistance.

METHODS

A total of 512 MRSA isolates were procured from 6 major hospitals in Riyadh, Saudi Arabia and antibiotic susceptibilities and MICs were documented against several antibiotics and vancomycin. SPSS version 10 was used for statistical analysis.

RESULTS

The prevalence of MRSA in the study hospitals ranged from 12% to 49.4%. Mean patient age was 44 years with males constituting 64.4% and females 35.6%. Approximately 41.5% of the isolates came from patients in the extreme age groups. MIC for vancomycin was in the susceptible range for all isolates ranging from 0.25 to 3 ug/ml. The overall susceptibility of MRSA to the various antibiotics tested was: fusidic acid 4.3%, sulfamethoxazole/trimethoprim 33.8%, gentamicin 39.6%, mupirocin 77.0%, gatifloxacin 78.9%, chloramphenicl 80.7%, linezolid 95.1%, quinupristin/dalfopristin 100%. Some differences were noted in the resistance of isolates among the participating hospitals reflecting antibiotic usage. On the whole, inpatient isolates (accounting for 77.5% of the isolates) were more resistant than outpatient isolates (22.5%) except for linezolid. Quinupristin-dalfopristin and linezolid are the most effective antibiotics tested against inpatient isolates while quinupristin-dalfopristin and gatifloxacin seem to be the most effective against outpatient isolates. Approximately one forth of the isolates are no longer susceptible to mupirocin used for eradication of the carrier state reflecting resistance developing after widespread use. Trends over time show a tendency towards decreased susceptibility to gatifloxacin and linezolid with increasing susceptibility to gentamicin and sulfamethoxazole/trimethoprim.

CONCLUSION

Quinupristin/dalfopristin and linezolid are two valuable additions to our antimicrobial armamentarium, but resistance has already been described. To preserve their value, their use should be limited to those rare cases where they are clearly needed. Fusidic acid, the local antibiotic, gentamicin and trimethoprim/sulfamethoxazole should not be relied upon for treatment of MRSA infections, at least empirically as the percentage of susceptible isolates is very low.

Methicillin-resistant Staphylococcus aureus on orthopaedic wards: incidence, spread, mortality, cost and control

We examined the rates of infection and colonisation by methicillin-resistant Staphylococcus aureus (MRSA) between January 2003 and May 2004 in order to assess the impact of the introduction of an MRSA policy in October 2003, which required all admissions to be screened. Emergency admissions were treated prophylactically and elective beds ring-fenced. A total of 5,594 admissions were cross-referenced with 22,810 microbiology results. The morbidity, mortality and cost of managing MRSA-carrying patients, with a proximal fracture of the femur were compared, in relation to age, gender, American Society of Anaesthesiologists grade and residential status, with a group of matched controls who were MRSA-negative. In 2004, we screened 1795 of 1,796 elective admissions and MRSA was found in 23 (1.3%). We also screened 1,122 of 1,447 trauma admissions and 43 (3.8%) were carrying MRSA. All ten ward transfers were screened and four (40%) were carriers (all p < 0.001). The incidence of MRSA in trauma patients increased by 2.6% per week of inpatient stay (r = 0.97, p < 0.001). MRSA developed in 2.9% of trauma and 0.2% of elective patients during that admission (p < 0.001). The implementation of the MRSA policy reduced the incidence of MRSA infection by 56% in trauma patients (1.57% in 2003 (17 of 1,084) to 0.69% in 2004 (10 of 1,447), p = 0.035). Infection with MRSA in elective patients was reduced by 70% (0.56% in 2003 (7 of 1,257) to 0.17% in 2004 (3 of 1,806), p = 0.06). The cost of preventing one MRSA infection was 3,200 pounds. Although colonisation by MRSA did not affect the mortality rate, infection by MRSA more than doubled it. Patients with proximal fractures of the femur infected with MRSA remained in hospital for 50 extra days, had 19 more days of vancomycin treatment and 26 more days of vacuum-assisted closure therapy than the matched controls. These additional costs equated to 13,972 pounds per patient. From this experience we have been able to describe the epidemiology of MRSA, assess the impact of infection-control measures on MRSA infection rates and determine the morbidity, mortality and economic cost of MRSA carriage on trauma and elective orthopaedic wards.