Understanding and Controlling Methicillin-ResistantStaphylococcus aureusInfections

Use of the Performance Diagnostic Checklist-Human Services to Assess Hand Hygiene Compliance in a Hospital

Poor hand hygiene in hospital settings leads to the spread of communicable disease to a population of individuals already medically compromised. The current study used the Performance Diagnostic Checklist-Human Services to develop an intervention targeting hand hygiene compliance for nine participants employed by an inpatient unit. The use of performance feedback and goal setting improved hand hygiene compliance when compared to baseline for eight of nine participants. Results are discussed in terms of strategies for using performance analysis to identify effective interventions to address performance deficits.

Risk Factors And Clinical Outcomes Of Hospital-Acquired MRSA Infections In Chongqing, China

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen of hospital infection with multi-drug resistant characteristics. Its spread and epidemic pose great challenges to nosocomial infection control. This study was aimed to identify risk factors for hospital-acquired MRSA (HA-MRSA) infections and investigate its clinical outcome, developing infection control strategies and improving patient outcomes.

Methods

A retrospective case-case-control study was conducted to compare patients in Southwest Hospital, Chongqing, People's Republic of China from January 2018 to December 2018 with control patients. In this study, 251 patients with MRSA nosocomial infection, 339 patients with methicillin-sensitive Staphylococcus aureus strains (MSSA) nosocomial infection, and 300 patients with non-Staphylococcus aureus infection were included.

Results

Multivariate analysis showed that presence of central venous catheters (odds ratio [OR], 1.932; 95% confidence interval [CI], 1.074–3.477; P=0.028), sputum suction (OR, 2.887; 95% CI, 1.591–5.240; p<0.001), and total hospital stays more than 30 days (OR, 3.067; 95% CI, 2.063–4.559; P<0.001) were independent risk factors for HA-MRSA. Renal insufficiency (OR, 2.744; 95% CI, 1.089–6.914; P=0.032) and receipt of immunosuppressors (OR, 3.140; 95% CI, 1.284–7.678; P=0.012) were independent predictors of poor prognosis of MRSA nosocomial infection. Moreover, empirical use of antibiotics (OR, 0.514; 95% CI, 0.282–0.935; P=0.029) was a protective factor for poor prognosis of MRSA nosocomial infection. In-hospital mortality in the MRSA group was not statistically significant compared with the other two groups; however, the rate of poor prognosis in the MRSA group was higher than that of the MSSA group (27.5% vs 17.1%, χ²=9.200, P=0.002) and the control group (27.5% vs 16.0%, χ²=19.190, P=0.001).

Conclusion

Our results have shown presence of central venous catheters, sputum suction, and total hospital stays more than 30 days were associated with nosocomial MRSA infection. Patients with renal insufficiency and immunosuppressive therapy were more likely to cause poor prognosis with MRSA infection, and the empirical use of antibiotics can effectively reduce the adverse clinical outcomes caused by MRSA infection. Based on above findings, strategies to control MRSA infection should emphasize more attention to these patients and appropriate empirical use of antibiotics.

Indoor hospital air and the impact of ventilation on bioaerosols: a systematic review

Healthcare-acquired infections (HAIs) continue to persist in hospitals, despite the use of increasingly strict infection-control precautions. Opportunistic airborne transmission of potentially pathogenic bioaerosols may be one possible reason for this persistence. Therefore, this study aimed to systematically review the concentrations and compositions of indoor bioaerosols in different areas within hospitals and the effects of different ventilation systems. Electronic databases (Medline and Web of Science) were searched to identify articles of interest. The search was restricted to articles published from 2000 to 2017 in English. Aggregate data was used to examine the differences in mean colony forming units per cubic metre (cfu/m³) between different hospital areas and ventilation types. A total of 36 journal articles met the eligibility criteria. The mean total bioaerosol concentrations in the different areas of the hospitals were highest in the inpatient facilities (77 cfu/m³, 95% confidence interval (CI): 55-108) compared with the restricted (13cfu/m³, 95% CI: 10-15) and public areas (14 cfu/m³, 95% CI: 10-19). Hospital areas with natural ventilation had the highest total bioaerosol concentrations (201 cfu/m³, 95% CI: 135-300) compared with areas using conventional mechanical ventilation systems (20 cfu/m³, 95% CI: 16-24). Hospital areas using sophisticated mechanical ventilation systems (such as increased air changes per hour, directional flow and filtration systems) had the lowest total bioaerosol concentrations (9 cfu/m³, 95% CI: 7-13). Operating sophisticated mechanical ventilation systems in hospitals contributes to improved indoor air quality within hospitals, which assists in reducing the risk of airborne transmission of HAIs.

Improving physician hand hygiene compliance using behavioural theories: a study protocol

BACKGROUND

Healthcare-associated infections affect 10% of patients in Canadian acute-care hospitals and are significant and preventable causes of morbidity and mortality among hospitalized patients. Hand hygiene is among the simplest and most effective preventive measures to reduce these infections. However, compliance with hand hygiene among healthcare workers, specifically among physicians, is consistently suboptimal. We aim to first identify the barriers and enablers to physician hand hygiene compliance, and then to develop and pilot a theory-based knowledge translation intervention to increase physicians' compliance with best hand hygiene practice.

DESIGN

The study consists of three phases. In Phase 1, we will identify barriers and enablers to hand hygiene compliance by physicians. This will include: key informant interviews with physicians and residents using a structured interview guide, informed by the Theoretical Domains Framework; nonparticipant observation of physician/resident hand hygiene audit sessions; and focus groups with hand hygiene experts. In Phase 2, we will conduct intervention mapping to develop a theory-based knowledge translation intervention to improve physician hand hygiene compliance. Finally, in Phase 3, we will pilot the knowledge translation intervention in four patient care units.

DISCUSSION

In this study, we will use a behavioural theory approach to obtain a better understanding of the barriers and enablers to physician hand hygiene compliance. This will provide a comprehensive framework on which to develop knowledge translation interventions that may be more successful in improving hand hygiene practice. Upon completion of this study, we will refine the piloted knowledge translation intervention so it can be tested in a multi-site cluster randomized controlled trial.

Microbiology of Acute and Chronic Maxillary Sinusitis in Smokers and Nonsmokers

Objectives:

We evaluated the microbiology of sinus aspirates of smokers and nonsmokers with acute and chronic maxillary sinusitis.

Methods:

Cultures were obtained from 458 patients, 244 (87 smokers and 157 nonsmokers) of whom had acute maxillary sinusitis and 214 (84 smokers and 130 nonsmokers) of whom had chronic maxillary sinusitis, between 2001 and 2007.

Results:

A greater number of Staphylococcus aureus, methicillin-resistant S aureus (MRSA), and beta-lactamase–producing bacteria (BLPB) were found in the 87 smokers with acute sinusitis than in the nonsmokers with acute sinusitis (p < 0.005, p < 0.025, and p < 0.05, respectively). A greater number of these organisms were found in the 84 smokers with chronic sinusitis than in the nonsmokers (p < 0.01, p < 0.025, and p < 0.001, respectively). Eighty-five BLPB isolates were recovered from 73 patients (30%) with acute sinusitis. These included Moraxella catarrhalis, S aureus, Haemophilus influenzae, Prevotella spp, and Fusobacterium spp; 40 BLPB isolates were found in smokers, and 45 in nonsmokers (p < 0.05). One hundred twenty-five BLPB isolates were recovered from 91 patients (43%) with chronic sinusitis, including M catarrhalis, Bacteroides fragilis group, S aureus, H influenzae, Prevotella spp. and Fusobacterium spp; 69 BLPB isolates were found in smokers, and 56 in nonsmokers (p < 0.001). Antimicrobial therapy had been administered in the past month to 130 patients (28%; 60 smokers and 70 nonsmokers; p < 0.025). Both MRSA and BLPB were isolated more often from these individuals (p < 0.025). However, the higher isolation rates of MRSA and BLPB in smokers were independent of previous antimicrobial therapy.

Conclusions:

These data illustrate a greater frequency of isolation of S aureus, MRSA, and BLPB in patients with acute and chronic sinusitis who smoke.

Patient-associated risk factors for acquisition of methicillin-resistant Staphylococcus aureus in a tertiary care hospital

BACKGROUND

Determining risk factors for acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals is important for defining infection-control measures that may lead to fewer hospital-acquired infections.

OBJECTIVE

To determine patient-associated risk factors for acquisition of MRSA in a tertiary care hospital with the goal of identifying modifiable risk factors.

METHODS

A retrospective matched case-control study was performed. Case patients who acquired MRSA during hospitalization and 2 matched control patients were selected among inpatients admitted to target units during the period from 2001 through 2008. The odds of exposure to potential risk factors were compared between case patients and control patients, using matched univariate conditional logistic regression. A single multivariate conditional logistic regression model identifying independent patient-specific risk factors was generated.

RESULTS

A total of 451 case patients and 866 control patients were analyzed. Factors positively associated with MRSA acquisition were as follows: target unit stay before index culture; primary diagnosis of respiratory disease, digestive tract disease, injury or trauma, or other diagnosis compared with cardiocirculatory disease; peripheral vascular disease; mechanical ventilation with pneumonia; ventricular shunting or ventriculostomy; and ciprofloxacin use. Factors associated with decreased risk were receipt of a solid-organ transplant and use of penicillins, cephalosporins, rifamycins, daptomycin or linezolid, and proton pump inhibitors.

CONCLUSION

Among the factors associated with increased risk, few are modifiable. Patients with at-risk conditions could be targeted for intensive surveillance to detect acquisition sooner. The association of MRSA acquisition with target unit exposure argues for rigorous application of hand hygiene, appropriate barriers, environmental control, and strict aseptic technique for all procedures performed on such patients. Our findings support focusing efforts to prevent MRSA transmission and restriction of ciprofloxacin use.

Role of methicillin-resistant Staphylococcus aureus in head and neck infections

The prevalence of infection with methicillin-resistant Staphylococcus aureus is increasing. Methicillin-resistant Staphylococcus aureus is also being recognised as an important pathogen in head and neck infections. This review summarises studies published over the past two decades which illustrate the growing prevalence of methicillin-resistant Staphylococcus aureus, and the current therapeutic approaches to head and neck infections caused by this bacterium. These infections include sinusitis, otitis, periorbital cellulitis, cervical lymphadenitis, tonsillitis, thyroiditis, retropharyngeal abscess, and abscesses and wounds of the neck. Treatment of head and neck infections associated with methicillin-resistant Staphylococcus aureus includes drainage and debridement, as well as administration of local and systemic antimicrobials that provide coverage against these organisms and against potential aerobic and anaerobic pathogens that may be present if the infection is polymicrobial.

Bacteriology of spontaneously draining acute otitis media in children before and after the introduction of pneumococcal vaccination

Bacterial growth from spontaneously draining middle ear fluid was compared for periods before (1993-1998) and after (2001-2006) introduction of routine pneumococcal vaccination Staphylococcus aureus, including MRSA, was more common (P < .05) in the latter period.

Staphylococcal infections: a historical perspective

Staphylococcus aureus is an unusually successful and adaptive human pathogen that can cause epidemics of invasive disease despite its frequent carriage as a commensal. Over the past 100 years and more, S aureus has caused cycles of outbreaks in hospitals and the community and has developed resistance to every antibiotic used against it, yet the exact mechanisms leading to epidemics of virulent disease are not fully understood. Approaches such as bacterial interference have been effective in interrupting outbreaks, but to better prevent staphylococcal disease, we will need to be vigilant about environmental factors that facilitate its spread. Even more importantly, we need to understand more about the mechanisms that lead to its virulence and transmission. With such information, it may be possible to develop a vaccine that will prevent endemic and epidemic staphylococcal disease.

Acquisition of methicillin-resistant Staphylococcus aureus after living donor liver transplantation: a retrospective cohort study

BACKGROUND

The incidence and risk factors of methicillin-resistant Staphylococcus aureus (MRSA) acquisition after living donor liver transplantation (LDLT) are unclear. The aim of the present study was to assess the incidence and to analyze the risk factors for the acquisition of MRSA after LDLT in adults by multivariate analysis.

METHODS

We retrospectively reviewed the data from 158 adult patients that underwent LDLT at the Tokyo University Hospital. The microbiologic and medical records of the patients from admission to 3 months after LDLT were reviewed. Uni- and multivariate analyses were performed to identify the risk factors for postoperative acquisition of MRSA.

RESULTS

Postoperative MRSA acquisition was detected in 35 of 158 patients by median postoperative day 18. Age (>or= 60 y) and perioperative dialysis and/or apheresis predicted postoperative MRSA acquisition by multivariate analysis. In contrast, postoperative use of fluoroquinolone was negatively associated with acquisition of MRSA.

CONCLUSION

MRSA arose early after LDLT in adults with a high incidence (35 of 158 patients). Surveillance culture should be checked periodically after LDLT to identify and prevent the transmission of MRSA.

Impact of new methicillin-resistant Staphylococcus aureus carriage postoperatively after living donor liver transplantation

BACKGROUND

Preoperative carriage of methicillin-resistant Staphylococcus aureus (MRSA) is associated with an increased risk of MRSA infection after liver transplantation. It is not known, however, whether new MRSA carriage postoperatively also increases the risk of MRSA infection after liver transplantation.

METHODS

We retrospectively reviewed the data from 242 adult patients who underwent living donor liver transplantation (LDLT) including microbiological and medical records from admission to 3 months after LDLT. Uni and multivariate analyses were performed to identify independent risk factors for postoperative MRSA infection among preoperative noncarriers of MRSA.

RESULTS

Postoperative MRSA infection occurred in 18 of 219 preoperative noncarriers of MRSA by median postoperative day 26. Operation time of at least 16 hours and postoperative colonization with MRSA independently predicted postoperative MRSA infection.

CONCLUSION

Postoperative surveillance cultures should be performed periodically after liver transplantation to identify high-risk candidates for postoperative MRSA infection, even among preoperative noncarriers of MRSA.

Methicillin-resistant Staphylococcus aureus infection after living-donor liver transplantation in adults

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) infection frequently complicates the postoperative course in deceased-donor liver transplantation. The incidence and risk factors of MRSA infection after Living-donor Liver transplantation (LDLT), however, are unclear.

METHODS

We retrospectively reviewed the data from 242 adult patients who underwent LDLT at the University of Tokyo Hospital. The microbiologic and medical records of the patients from admission to 3 months after LDLT were reviewed. Uni- and multivariate analyses were performed to identify the independent risk factors for postoperative MRSA infection.

RESULTS

Postoperative MRSA infection occurred in 25 of 242 patients by median postoperative day 23. Preoperative MRSA colonization, preoperative use of antimicrobials, operation time (> or =16 h), and postoperative apheresis independently predicted postoperative MRSA infection.

CONCLUSION

Surveillance culture should be checked periodically after admission to identify patients at high risk for MRSA infection and to administer appropriate antimicrobials for perioperative infection. Postoperative apheresis, suggesting postoperative liver dysfunction, predisposed patients to MRSA infection.

Efficacy of mastoidectomy on MRSA-infected chronic otitis media with tympanic membrane perforation

OBJECTIVES

To retrospectively evaluate the efficacy of mastoidectomy on methicillin-resistant Staphylococcus aureus (MRSA)-infected chronic otitis media in comparison with methicillin-susceptible Staphylococcus aureus (MSSA)-infected otitis media.

METHODS

Between January 1998 and October 2003, 18 ears underwent surgery for MRSA-infected chronic otitis media with tympanic membrane perforation at the Department of Otolaryngology, Hyogo College of Medicine. Another 33 ears underwent surgery for MSSA-infected chronic otitis media with tympanic membrane perforation during the same period. The postoperative results of graft success rate, hearing results and other complications were compared between MRSA-infected and MSSA-infected ears with or without mastoidectomy, and discharging or dry ears.

RESULTS

In MRSA, the mastoidectomy group tended to have a better graft success rate than the non-mastoidectomy group. In MSSA, there were almost the same graft success rate and hearing results between the mastoidectomy and non-mastoidectomy groups regardless of the presence of discharge. In MRSA-infected discharging ears, the rate of postoperative complications (ear drum perforation, persistent otorrhea, and dehiscence of skin incision) were significantly lower in the mastoidectomy group than in the non-mastoidectomy group (p=0.046).

CONCLUSION

Mastoidectomy had significantly better results concerning postoperative complications in discharging ears with MRSA-infected chronic otitis media. We recommend performing tympanoplasty with mastoidectomy in MRSA-infected chronic otitis media.

Infection of surgical wounds in the maxillofacial region and free flap donor sites with methicillin-resistant Staphylococcus aureus

We studied the acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in two groups of patients who had free flap reconstructions of defects after excision of lesions in the head and neck. The first group (n=31) was given a 5-day perioperative course of antibiotic prophylaxis (long-term) and the second (n=33) a 24-h course (short-term). MRSA was the main infecting organism. Seventeen of the 64 patients (27%) developed an infection with MRSA, including seven at donor sites of free flaps. All infections were acquired after operation, and delayed healing or discharge in five patients with MRSA and four with infections with other organisms. The median length of hospital admission was greater for patients that acquired MRSA (p=0.005). There were significantly fewer patients with wounds infected by MRSA in the short-term group (4/33 compared with 13/31, p=0.01). We recommend the short-term use of an antibiotic for surgical prophylaxis and the application of cross-infection control measures on the ward.

Guidelines for the prophylaxis and treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the UK

These evidence-based guidelines have been produced after a literature review of the treatment and prophylaxis of methicillin-resistant Staphylococcus aureus (MRSA) infection. The guidelines were further informed by antibiotic susceptibility data on MRSA from the UK. Recommendations are given for the treatment of common infections caused by MRSA, elimination of MRSA from carriage sites and prophylaxis of surgical site infection. There are several antibiotics currently available that are suitable for use in the management of this problem and potentially useful new agents are continuing to emerge.

Infectious Complications of Cancer Therapy

Advances in the management of cancer, particularly the development of new chemotherapeutic agents, have greatly improved the survival and outcome of patients with hematologic malignancies and solid tumors; overall 5-year survival rates in cancer patients have improved from 39% in the 1960s to 60% in the 1990s.1 However, infection, caused by both the underlying malignancy and cancer chemotherapy, particularly myelosuppressive chemotherapy, remains a persistent challenge.

Less skin irritation from alcohol-based disinfectant than from detergent used for hand disinfection

BACKGROUND

The benefit of alcohol-based disinfectant used on normal skin has been debated.

OBJECTIVES

The objective of the present study was to compare the effects of repeated exposure to an alcohol-based disinfectant, a detergent and an alcohol-based disinfectant/detergent alternately for 10 days, including noninvasive measurements in the evaluation. Skin reactivity in irritated skin after a 4-week interval was also evaluated.

MATERIALS AND METHODS

Detergent, disinfectant and alternate disinfectant and detergent were applied twice daily every 10 min for 1 h to the ventral upper arms and forearms of 17 healthy volunteers. A control area was included. After 4 weeks an SLS patch was applied to each area. Irritant reactions were quantified with a visual score recording and measurements of transepidermal water loss (TEWL) and skin colour were performed on days 1, 5, 11, 38 and 40.

RESULTS

On day 5 the detergent caused a higher visual score than either disinfectant applied alone or alternate disinfectant and detergent, P < 0.05. On day 11 detergent and alternate disinfectant and detergent caused a higher score than disinfectant, P < 0.05. An increased irritant response for detergent compared with disinfectant alone and alternate disinfectant and detergent was confirmed by TEWL evaluations on days 5 and 11, P < 0.001, while no significant difference was found by colour measurement. After 4 weeks, when evaluated by colour measurement, significantly less response to the SLS patch was found on the disinfectant-treated area compared with the control area and detergent area, and a similar trend was found for TEWL, although it was not statistically significant.

CONCLUSION

Alcohol-based disinfectant caused less visible skin irritation and less skin barrier disruption than the use of detergent. The alternate use of detergent and disinfectant caused less irritation than the use of detergent, and a possible interaction between the two irritants was not indicated. After 4 weeks there was a tendency for decreased skin reactivity in the skin areas which had 4 weeks previously been exposed to disinfectant.

Short-term effects of alcohol-based disinfectant and detergent on skin irritation

The most important risk factor for occupational contact dermatitis in hospital personnel is the exposure to irritants such as water, detergents and alcohol-based solutions. This study was undertaken to evaluate the short-term effects of repeated exposure to an alcohol-based disinfectant, to a detergent and to an alcohol-based disinfectant/detergent alternately. The hardening effect in preirritated skin after a 4-week interval was also evaluated. Detergent, disinfectant and disinfectant/detergent alternately were applied daily every 15 min for 6 h for 2 days to the flexor upper arms and forearms of 15 volunteers. A control area was included. After 4 weeks, a sodium lauryl sulfate patch was applied to each area. Irritant reactions were quantified by visual score, transepidermal water loss (TEWL) and skin colour at baseline, D3, D8, D35 and D37. As evaluated by clinical assessment, detergent caused more redness of the skin than both disinfectant applied alone and disinfectant/detergent alternately at D3 and D8, P < 0.001 and P < 0.001, respectively. An increased irritant response for detergent as compared to disinfectant alone and disinfectant/detergent was confirmed by TEWL and colour evaluations, P = 0.001 and P = 0.001 and P = 0.006 and P = 0.009, respectively. No hardening effect in preirritated skin was found after a 4-week interval. In conclusion, hand disinfection with alcohol-based disinfectant or alternate use of disinfectant/detergent causes less skin irritation than hand disinfection with a detergent. This study evaluated the short-term effects of disinfectant and detergent exposure only, and more long-term studies are necessary before recommendations can be made.

Risk factors for colonization with methicillin-resistant Staphylococcus aureus in a long-term-care facility in Slovenia

OBJECTIVE

To evaluate risk factors associated with methicillin-resistant Staphylococcus aureus (MRSA) colonization in a long-term-care facility (LTCF) for the elderly in Slovenia.

SETTING

A 351-bed community LTCF for the elderly.

DESIGN AND PARTICIPANTS

This was a case-control study. MRSA carriage was identified in 102 of 127 residents of the facility's nursing unit. Two swabs were taken: one from the anterior nares and one from the largest skin lesion. If no skin lesions were present, the axillae and the groin area were swabbed. Data were collected regarding gender, age, length of stay in the facility, underlying conditions, functional status, presence of wounds or pressure sores, presence of catheters, antibiotic treatments, and hospital admissions.

RESULTS

We detected MRSA in 12 participants. Risk factors independently and significantly associated with MRSA colonization on the multivariate analysis were antibiotic treatments within 1 month before the investigation (odds ratio, 5.087; 95% confidence interval, 1.02 to 25.48; P = .048) and multiple hospital admissions in the 3 months before the investigation (odds ratio, 6.277; 95% confidence interval, 1.31 to 30.05; P = .022).

CONCLUSIONS

This is the first assessment of risk factors for colonization with MRSA in an LTCF in Slovenia. MRSA poses a problem in this LTCE Our observations may be valuable in implementing active surveillance cultures in infection control programs in Slovenian LTCFs.

Incidence of methicillin-resistant Staphylococcus aureus causing chronic rhinosinusitis

OBJECTIVE/HYPOTHESIS

To identify the incidence of methicillin-resistant Staphylococcus aureus (MRSA) causing chronic rhinosinusitis (CRS) and identify whether antibiotic use and previous endoscopic sinus surgeries (ESS) contribute to its development.

STUDY DESIGN

A retrospective case control analysis, with the control group randomly selected and matched for age and sex.

METHODS

All patients undergoing an endonasal culture in a tertiary otolaryngology center between April 2001 and March 2003 for mucopurulent rhinosinusitis were identified. A chart review was undertaken to identify those patients with a positive MRSA culture result. An age- and sex-matched control group was randomly chosen, and an interview was conducted to identify antibiotic use and previous ESS. A statistical analysis on these two variables was carried out using a t test and the Wilcoxon rank-sum test.

RESULTS

Two hundred eighty cultures were identified in 188 patients, and of these, 264 cultures in 173 patients met the inclusion criteria. There were 141 positive cultures and 13 positive MRSA cultures. The overall incidence of MRSA in this population was 9.22%. The mean number of antibiotic courses in the MRSA and the control groups was 33.2 and 26.7, respectively, which was not statistically significant (P =.43). The 95% confidence interval (CI) for this mean difference of 6.5 is -9.8 to 22.8. The mean number of ESS in the MRSA and control groups was 2.0 and 1.9, respectively, which was not statistically significant (P =.93). The 95% CI for this mean difference of 0.06 is -1.3 to 1.4.

CONCLUSIONS

We identified a 9.22% incidence of MRSA-causing CRS. The frequency of antibiotic use and previous ESS were found not to be statistically significant causes of MRSA sinusitis. However, the 95% CI for antibiotic usage is skewed to the right, indicating a possible role for its contribution to the emergence of MRSA-causing CRS.

Rapid screening and identification of methicillin-resistant Staphylococcus aureus from clinical samples by selective-broth and real-time PCR assay

A screening method for methicillin-resistant Staphylococcus aureus (MRSA) by using selective broth and real-time PCR (broth-PCR) was developed and evaluated. The samples (n = 304) were cultured in the broth overnight, followed by nuc gene detection by real-time PCR. nuc-negative samples were further checked for the presence of nuc amplification inhibitors by a PCR internal inhibitor assay. nuc-positive samples and nuc-negative samples with PCR inhibitors were cultured onto plates and processed further. The diagnostic values for this MRSA screening method were 93.3% sensitivity, 89.6% specificity, 31.8% positive predictive value, and 99.6% negative predictive value. The application of the broth-PCR method will be able to report most of the negative samples (258 of 289 [89.3%]) on the next morning and can save as much as 84.9% (258 of 304) of the labor and cost spent on processing the nuc-negative specimens on plates. In the study, all the samples were processed in parallel by the broth enrichment method and the plating method for comparison. To identify MRSA, the isolated oxacillin-resistant S. aureus strains were tested by a duplex real-time PCR targeting the mecA gene and the nuc gene. A collection of MRSA, methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, and methicillin-susceptible Staphylococcus epidermidis strains and a panel of standard strains of 11 bacterial species other than S. aureus were also tested by this method, which was proved to be a valuable tool for MRSA identification in a routine microbiological laboratory.