Methicillin-resistant Staphylococcus aureus and antimicrobial use in Belgian hospitals

Nasopharyngeal Carriage and Antimicrobial Susceptibility Profile of Staphylococcus aureus among Children under Five Years in Accra

This cross-sectional study investigated the Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) nasopharyngeal carriage epidemiology in Accra approximately five years post-pneumococcal conjugate vaccines introduction in the country. Archived nasopharyngeal swabs collected from 410 children aged under five years old were bacteriologically cultured. The resultant S. aureus isolates were subjected to antimicrobial susceptibility testing and screening for carriage of the mecA and LukF-PV (pvl) genes, following standard procedures. The data obtained were analyzed with Statistical Products and Services Solutions (SPSS) using descriptive statistics and Chi square tests of associations. The isolated bacteria decreased across coagulase-negative Staphylococci (47.3%, n = 194), S. aureus (23.2%, n = 95), Diphtheroids (5.4%, n = 22), Micrococcus species (3.7%, n = 15), Klebsiella pneumoniae (3.2%, n = 13), Moraxella species and Citrobacter species (1.5% each, n = 6), Escherichia coli, Enterobacter species, and Pseudomonas species (0.9% each, n = 2). The MRSA carriage prevalence was 0.49% (n = 2). Individuals aged 37-48 months recorded the highest proportion of S. aureus carriage (32.6%, 31/95). Resistance of S. aureus to the antibiotics tested were penicillin G (97.9%, n = 93), amoxiclav (20%, n = 19), tetracycline (18.9%, n = 18), erythromycin (5.3%, n = 5), ciprofloxacin (2.1%, n = 2), gentamicin (1.1%, n = 1), cotrimoxazole, clindamycin, linezolid, and teicoplanin (0% each). No inducible clindamycin resistance was observed for the erythromycin-resistant isolates. Three (3.2%) of the isolates were multidrug resistant, of which 66.7% (2/3) were MRSA. The pvl gene was associated with 59.14% (55/93) of the methicillin-sensitive S. aureus (MSSA) isolates, but was not detected among any of the MRSA isolates.

'Warning: allergic to penicillin': association between penicillin allergy status in 2.3 million NHS general practice electronic health records, antibiotic prescribing and health outcomes

BACKGROUND

The prevalence of reported penicillin allergy (PenA) and the impact these records have on health outcomes in the UK general population are unknown. Without such data, justifying and planning enhanced allergy services is challenging.

OBJECTIVES

To determine: (i) prevalence of PenA records; (ii) patient characteristics associated with PenA records; and (iii) impact of PenA records on antibiotic prescribing/health outcomes in primary care.

METHODS

We carried out cross-sectional/retrospective cohort studies using patient-level data from electronic health records. Cohort study: exact matching across confounders identified as affecting PenA records. Setting: English NHS general practices between 1 April 2013 and 31 March 2014. Participants: 2.3 million adult patients. Outcome measures: prevalence of PenA, antibiotic prescribing, mortality, MRSA infection/colonization and Clostridioides difficile infection.

RESULTS

PenA prevalence was 5.9% (IQR = 3.8%-8.2%). PenA records were more common in older people, females and those with a comorbidity, and were affected by GP practice. Antibiotic prescribing varied significantly: penicillins were prescribed less frequently in those with a PenA record [relative risk (RR)  = 0.15], and macrolides (RR = 4.03), tetracyclines (RR = 1.91) nitrofurantoin (RR = 1.09), trimethoprim (RR = 1.04), cephalosporins (RR = 2.05), quinolones (RR = 2.10), clindamycin (RR = 5.47) and total number of prescriptions were increased in patients with a PenA record. Risk of re-prescription of a new antibiotic class within 28 days (RR = 1.32), MRSA infection/colonization (RR = 1.90) and death during the year subsequent to 1 April 2013 (RR = 1.08) increased in those with PenA records.

CONCLUSIONS

PenA records are common in the general population and associated with increased/altered antibiotic prescribing and worse health outcomes. We estimate that incorrect PenA records affect 2.7 million people in England. Establishing true PenA status (e.g. oral challenge testing) would allow more people to be prescribed first-line antibiotics, potentially improving health outcomes.

Utilization, Spending, and Price Trends for Quinolones in the US Medicaid Programs: 25 Years' Experience 1991-2015

BACKGROUND

Given that the quinolones is one of the antibacterial classes most frequently used to treat patients with bacterial infections in the United States, any change in prescribing patterns of quinolones will impact Medicaid medical expenditures.

OBJECTIVES

This study was undertaken to examine trends in utilization, reimbursement, and prices of quinolone antibacterials for the US Medicaid population.

METHODS

The publicly available Medicaid State Drug Utilization outpatient pharmacy files were used for this study. Quarterly and annual prescription counts and reimbursement amounts were calculated for each of the quinolones reimbursed by Medicaid from quarter 1, 1991 through quarter 2, 2015. Average per-prescription reimbursement, as a proxy for drug price, was calculated as the drug reimbursement divided by the number of prescriptions.

RESULTS

The total annual number of quinolone prescriptions increased 402%, from 247,395 in the first quarter of 1991 to 1.2 million in the second quarter of 2015, peaking at 1.3 million in the first quarter of 2005. Similarly, the total reimbursement for quinolone agents increased by 245.5% over the same period. More than 80% of quinolone prescriptions reimbursed by Medicaid were for the second-generation agent, ciprofloxacin, and the third-generation agent, levofloxacin. The average payment per prescription for quinolones increased from US$43.8 in the first quarter of 1991 to US$87.6 in the second quarter of 2015.

CONCLUSIONS

A substantial rise in Medicaid expenditures on quinolones was observed during the 25-year study period, which was mainly because of rising utilization. Therefore, there is a need for additional research that has access to clinically relevant data with which to measure the rate of inappropriate quinolone use among the Medicaid population and associated clinical outcomes and healthcare costs.

Dissimilar Fitness Associated with Resistance to Fluoroquinolones Influences Clonal Dynamics of Various Multiresistant Bacteria

Fitness cost associated with resistance to fluoroquinolones was recently shown to vary across clones of methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase-producing Klebsiella pneumoniae. The resulting dissimilar fitness should have influenced the clonal dynamics and thereby the rates of resistance for these pathogens. Moreover, a similar mechanism was recently proposed for the emergence of the H30 and H30R lineages of ESBL-producing E. coli and the major international clone (ribotype 027) of Clostridium difficile. Furthermore, several additional international clones of various multiresistant bacteria are suspect to have been selected by an analogous process. An ability to develop favorable mutations in the gyrase and topoisomerase IV genes seems to be a prerequisite for pathogens to retain fitness while showing high-level resistance to fluoroquinolones. Since, the consumption of other "non-fluoroquinolone" groups of antibiotics have also contributed to the rise in resistance rates a more judicious use of antibiotics in general and of fluoroquinolones in particular could ameliorate the international resistance situation.

Methicillin-ResistantStaphylococcus aureusin German Intensive Care Units During 2000-2003: Data from Project SARI (Surveillance of Antimicrobial Use and Antimicrobial Resistance in Intensive Care Units)

Objectives.

The objective of this study was to analyze methicillin-resistantStaphylococcus aureus(MRSA) percentages (defined as the percentage ofS. aureusisolates that are resistant to methicillin) and antimicrobial consumption in intensive care units (ICUs) participating in Project SARI (Surveillance of Antimicrobial Use and Antimicrobial Resistance in Intensive Care Units), to look for temporal changes in MRSA percentages and antimicrobial consumption in individual ICUs as an indicator of the impact of an active surveillance system, and to investigate the differences between ICUs with increased MRSA percentages versus those with decreased percentages during a period of 3 years (2001-2003).

Methods.

This was a prospective, ICU-based and laboratory-based surveillance study involving 38 German ICUs during 2000-2003. Antimicrobial use was reported in terms of defined daily doses (DDDs) per 1,000 patient-days. Temporal changes in the MRSA percentage and antimicrobial use in individual ICUs were calculated by means of the Wilcoxon signed rank test. The incidence density of nosocomial MRSA infection was defined as the number of nosocomial MRSA infections per 1,000 patient-days.

Results.

From February 2000 through December 2003, a total of 38 ICUs reported data on 499,694 patient-days and 9,552S. aureusisolates, including 2,249 MRSA isolates and 660,029 DDDs of antimicrobials. Cumulative MRSA percentages ranged from 0% to 64.4%, with a mean of 23.6%. The MRSA incidence density ranged from 0 to 38.2 isolates per 1,000 patient-days, with a mean of 2.77 isolates per 1,000 patient-days. There was a positive correlation between MRSA percentage and imipenem and ciprofloxacin use (P<.05). Overall, comparison of data from 2001 with data from 2003 showed that MRSA percentages increased in 18 ICUs (median increase, 13.2% [range, 1.6%-38.4%]) and decreased in 14 ICUs (median decrease, 12% [range, 1.0%-48.4%]). Increased use of third-generation cephalosporins, glycopeptides, or aminoglycosides correlated significantly with an increase in the MRSA percentage (P<.05). The cumulative nosocomial MRSA infection incidence density for 141 ICUs that did not participate in SARI and, therefore, did not receive feedback increased from 0.26 to 0.35 infections per 1,000 patient-days during a 3-year period, whereas the rate in SARI ICUs decreased from 0.63 to 0.40 infections per 1,000 patient-days.

Conclusion.

The MRSA situation in German ICUs is still heterogeneous. Because MRSA percentages range from 0% to 64.4%, further studies are required to confirm findings that no change in the MRSA percentage and a decrease in the nosocomial MRSA infection incidence density in SARI ICUs reflect the impact of an active surveillance system.

Importance of Control Group Selection for Evaluating Antimicrobial Use as a Risk Factor for Methicillin-ResistantStaphylococcus AureusBacteremia

Objective:

We investigated the importance of control group selection during an evaluation of antimicrobial use as a risk factor for methicillin-resistantStaphylococcus aureus(MRSA) bacteremia at our institution.

Methods:

We performed a case-control study. A case was defined as any patient admitted between January 1997 and May 2001 who developed nosocomial MRSA bacteremia. We used two control groups; control group I consisted of patients with nosocomial methicillin-susceptibleS. aureus(MSSA) bacteremia and control group II included only patients without bacteremia. We matched control-patients to case-patients using age, gender, time at risk, and hospital ward. Data collected on all patients included demographics, comorbidities, antibiotic use, time at risk, length of stay, severity of illness, and outcome.

Results:

We evaluated 63 patients (21 in each group). The three groups were well matched regarding age, gender, underlying diseases, and severity of illness. Patients in the MRSA group were more likely to have received a fluoroquinolone and had a higher mean number of days of fluoroquinolone use than did patients in the MSSA group (P= .027 andP= .015, respectively). However, all measures of fluoroquinolone use were similar for case-patients and for control-patients who did not have nosocomial bloodstream infection.

Conclusions:

Control group selection is important in evaluating antimicrobial use as a risk factor for MRSA bacteremia. Using control-patients infected with MSSA, rather than uninfected control-patients, may overestimate the association between antimicrobial use and MRSA infection. (Infect Control Hosp Epidemiol 2005;26:634-637)

Prior antibacterial drug exposure in dogs with meticillin-resistant Staphylococcus pseudintermedius (MRSP) pyoderma

BACKGROUND

The emergence of meticillin-resistant Staphylococcus pseudintermedius (MRSP) has become a significant animal health problem. Recent studies have indicated that previous antibacterial drug exposure is a factor in acquisition of meticillin-resistant strains of staphylococci.

HYPOTHESIS/OBJECTIVES

The purpose of this study was to identify factors associated with prior antimicrobial drug use and MRSP pyoderma in dogs presented to a veterinary teaching hospital.

ANIMALS

Dogs diagnosed with pyoderma associated with MRSP (n = 53) or meticillin-sensitive S. pseudintermedius (MSSP; n = 45).

METHODS

The medical records of dogs diagnosed with pyoderma associated with isolation of S. pseudintermedius between January 2006 and November 2012 were reviewed. All cases with a complete twelve month to 3 yr drug history prior to the diagnosis were included.

RESULTS

Fifty two of 53 (98%) MRSP cases and 42 of 45 (93%) MSSP cases had received at least one course of antibacterial drug prior to diagnosis. The total number of antibacterial drug prescriptions provided to pet owners and the variety of antibacterial drug classes represented were higher for cases with MRSP than for cases with MSSP (P < 0.0001 and P = 0.009, respectively). More cases with MRSP (98%) received beta-lactam drugs than those with MSSP (82%; P = 0.007) and the proportion of MRSP cases that had received concurrent immunomodulatory therapy was higher (62% versus 42%; P = 0.048).

CONCLUSIONS AND CLINICAL IMPORTANCE

These results suggest that the total number of antibacterial drug prescriptions, exposure to multiple drug classes (beta-lactams in particular) and concurrent immunomodulatory therapy may be associated with increased risk for acquisition of MRSP.

Acquisition of Methicillin-Resistant Staphylococcus aureus in the Acute Care Setting: Incidence and Risk Factors

Our objective was to assess the incidence of and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) acquisition among patients in acute care wards. For 5 months, patients were screened for MRSA colonization at admission and at discharge. At admission, 6.6% of patients had cultures positive for MRSA, and 3.1% of patients who had tested negative for MRSA on admission had cultures positive for MRSA at discharge. Only the presence of chronic skin breaks at admission was independently associated with MRSA acquisition.

Has the use of fluoroquinolones facilitated the widespread dissemination of methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase-producing Klebsiella pneumoniae in the healthcare setting?

Our group recently demonstrated that diverse fitness cost associated with resistance to fluoroquinolones allowed the extensive dissemination of the major international clones of both methicillin-resistant Staphylococcus aureus (MRSA) and multiresistant Klebsiella pneumoniae in the healthcare setting. The mechanism described by us was subsequently confirmed by British authors investigating the dynamics of MRSA clones in England. Our results imply that the use of fluoroquinolones should impact the incidence for both MRSA and multiresistant K. pneumoniae. A review of the related clinical studies mostly support this notion and shows that changes in the consumption of fluoroquinolone type antibiotics and the rates for both MRSA and multiresistant ESBL-producing K. pneumoniae remain usually in accordance. Though the association seems strong and the mechanism behind it unequivocal the use of fluoroquinolones should not be abandoned; a more judicious application can be recommended.

Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases)

BACKGROUND

Superficial bacterial folliculitis (SBF) is usually caused by Staphylococcus pseudintermedius and routinely treated with systemic antimicrobial agents. Infection is a consequence of reduced immunity associated with alterations of the skin barrier and underlying diseases that may be difficult to diagnose and resolve; thus, SBF is frequently recurrent and repeated treatment is necessary. The emergence of multiresistant bacteria, particularly meticillin-resistant S. pseudintermedius (MRSP), has focused attention on the need for optimal management of SBF.

OBJECTIVES

Provision of an internationally available resource guiding practitioners in the diagnosis, treatment and prevention of SBF.

DEVELOPMENT OF THE GUIDELINES

The guidelines were developed by the Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases, with consultation and advice from diplomates of the American and European Colleges of Veterinary Dermatology. They describe optimal methods for the diagnosis and management of SBF, including isolation of the causative organism, antimicrobial susceptibility testing, selection of antimicrobial drugs, therapeutic protocols and advice on infection control. Guidance is given for topical and systemic modalities, including approaches suitable for MRSP. Systemic drugs are classified in three tiers. Tier one drugs are used when diagnosis is clear cut and risk factors for antimicrobial drug resistance are not present. Otherwise, tier two drugs are used and antimicrobial susceptibility tests are mandatory. Tier three includes drugs reserved for highly resistant infections; their use is strongly discouraged and, when necessary, they should be used in consultation with specialists.

CONCLUSIONS AND CLINICAL IMPORTANCE

Optimal management of SBF will improve antimicrobial use and reduce selection of MRSP and other multidrug-resistant bacteria affecting animal and human health.

Canine superficial bacterial folliculitis: current understanding of its etiology, diagnosis and treatment

Superficial bacterial folliculitis (SBF) is more common in the dog than other mammalian species. Until recently, a successful outcome in cases of canine SBF was possible by administering a potentiated amoxicillin, a first generation cephalosporin or a potentiated sulfonamide. Unfortunately, this predictable susceptibility has changed, because methicillin resistant Staphylococcus pseudintermedius (MRSP) and Staphylococcus aureus (MRSA) are becoming more prevalent in canine SBF cases. The increasing frequency of multidrug resistance complicates the selection of antimicrobial therapy. Antimicrobial agents that were once rarely used in cases of canine SBF, such as amikacin, rifampicin and chloramphenicol, are becoming the drugs of choice, based on bacterial culture and susceptibility testing. Furthermore, changes in antimicrobial susceptibility have helped to re-emphasize the importance of a multimodal approach to treatment of the disease, including topical therapy. Due to the increasing frequency of identification of highly resistant Staphylococcus spp., topical antimicrobial therapy, including the use of diluted sodium hypochlorite (bleach), is becoming necessary to successfully treat some cases of canine SBF. Other important antiseptics that can be used include chlorhexidine, benzoyl peroxide, ethyl lactate, triclosan and boric acid/acetic acid. This review discusses the diagnostic and therapeutic management of canine SBF, with a special emphasis on treating methicillin resistant staphylococcal infections.

Economic implications of the dynamic relationship between antibiotic use and hospital-acquired infections

OBJECTIVES

The emergence and spread of antimicrobial resistance is still an unresolved problem worldwide. Recent evidence shows correlations between the volume of broad-spectrum antibiotics used in the hospital setting and the incidence of multidrug-resistant bacteria. According to this dynamic relationship, loss of antibiotic activity can be modeled as a negative externality of antibiotic consumption.

METHODS

The present study proposes to present an economic model describing the probability of antibiotic treatment failure as a function of antimicrobial use and alcohol-based hand-rub use. Furthermore, the results of recently conducted time-series analyses and cost-of-illness studies are applied to the model to determine the externalities of antibiotic consumption and alcohol-based hand-rub use with respect to the costs of hospital-acquired infections.

RESULTS

According to our calculations, the consumption of third-generation cephalosporins and fluoroquinolones is associated with the highest negative externalities (€143 and €101, respectively) because their use has been shown to be associated with most types of hospital-acquired infections. In contrast, the use of alcohol-based hand-rub solution for hand disinfection is associated with a positive externality of 41 cents per single disinfection of the hands.

CONCLUSIONS

The externalities presented in this work represent a possible application of cost-of-illness data to quantify the impact of antibiotic use on antimicrobial resistance. In addition, the results indicate that most economic research on the topic is biased in assuming the overall use of antibiotics to be responsible for the spread of antimicrobial resistance.

Predictors of agr dysfunction in methicillin-resistant Staphylococcus aureus (MRSA) isolates among patients with MRSA bloodstream infections

Despite emerging evidence that dysfunction in the accessory gene regulator (agr) locus is associated with deleterious outcomes among patients treated with vancomycin for methicillin-resistant Staphylococcus aureus (MRSA) infections, factors predictive of agr dysfunction have not been evaluated. This study describes the epidemiology of agr dysfunction, identifies predictors of agr dysfunction in MRSA isolates among those with MRSA bloodstream infections, and describes the relationship between agr dysfunction and other microbiologic phenotypes. A cross-sectional study of patients with MRSA bloodstream infections at two institutions in upstate New York was performed. Clinical data on demographics, comorbidities, disease severity, hospitalization history, and antibiotic history were collected. Microbiologic phenotypes, including agr dysfunction, MIC values by broth microdilution (BMD) and Etest, and vancomycin heteroresistance (hVISA) were tested. Multivariable analyses were performed to identify factors predictive of agr dysfunction. Among 200 patients with an MRSA bloodstream infection, the proportion of strains with agr dysfunction was 31.5%. The distribution of MICs determined by both BMD and Etest were equivalent across agr groups, and there was no association between agr dysfunction and the presence of hVISA. Severity of illness, comorbidities, and hospitalization history were comparable between agr groups. In the multivariate analysis, prior antibiotic exposure was the only factor of variables studied found to be predictive of agr dysfunction. This relationship was predominantly driven by prior beta-lactam and fluoroquinolone administration in the bivariate analysis. Identifying these institution-specific risk factors can be used to develop a process to assess the risk of agr dysfunction and guide empirical antibiotic therapy decisions.

Decline in the incidence of healthcare-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) correlates with deceased antimicrobial consumption at a tertiary care hospital in Taiwan, 2001-2009

The present study investigated the long-term impact of antibiotic use policy on the rates of consumption (expressed as daily-defined doses/1000 patient-days) of various parenteral antibiotics and on the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and the incidence of healthcare-associated MRSA (HA-MRSA) infection at a tertiary care hospital from 2001 to 2009. During this time, consumption of all antimicrobials for systemic use decreased by 33%. This change was driven by a 44% decrease in the consumption of unrestricted antibacterials, which was offset by a 42% increase in the consumption of restricted agents. The trends in MRSA prevalence (number of isolates/1000 patient-days) and HA-MRSA incidence (number of HA-MRSA-infected persons/1000 patient-days) correlated with the trend in overall consumption of antimicrobials. Significant positive correlations were observed between MRSA prevalence and the consumption of extended-spectrum and β-lactamase-resistant penicillins, first-generation cephalosporins, macrolides, lincosamides and streptogramins, aminoglycosides, and glycopeptides. Significant positive correlations were found between the incidence of HA-MRSA infection and the consumption of tetracyclines, extended-spectrum and β-lactamase-resistant penicillins, sulfonamides and trimethoprim, macrolides, lincosamides and streptogramins, and aminoglycosides. In conclusion, we have documented the ongoing successful reduction in total consumption of antimicrobials associated with a decrease in the incidence of HA-MRSA and the prevalence of MRSA over a 9-year period.

Antibiotic consumption as a driver for resistance in Staphylococcus aureus and Escherichia coli within a developing region

BACKGROUND

This study aimed to provide insight into possible antibiotic drivers of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli resistant to third-generation cephalosporins (3GCREC) in southern and eastern Mediterranean institutions.

METHODS

MRSA and 3GCREC susceptibility proportions from 19 regional hospitals, previously published by the ARMed project, were correlated with antibiotic use data from the same institutions.

RESULTS

Hospitals reporting below-median MRSA proportions had significantly lower total antibiotic use. MRSA proportions increased with greater use of carbapenems (P=.04). In multivariate analysis, a positive correlation was identified with the use of carbapenems (P=.002), combination penicillins (P=.018), and aminoglycosides (P=.014). No difference was ascertained between 3GCREC proportions and total antibiotic use. In multivariate linear regression, a correlation was identified only for 3GCREC (P=.005), but a negative association was evident for beta-lactamase-resistant penicillins (P=.010) and first-generation cephalosporins (P=.012).

CONCLUSIONS

The results suggest an association between resistance and antibiotic use, especially for carbapenems and third-generation cephalosporins. These data support the urgent implementation of antibiotic stewardship initiatives in hospitals in developing countries that focus on more judicious use of broad-spectrum formulations.

Impact of limited cephalosporin use on prevalence of methicillin-resistant Staphylococcus aureus in the intensive care unit

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a leading pathogen causing nosocomial infections. Many studies have shown that the restricted use of antibacterials is associated with a decline in resistance. To establish whether an intervention protocol designed to limit the use of cephalosporins can lower mRSA infection rates and impact on Gram-negative bacteria susceptibility in an intensive Care Unit (ICU), we conducted a prospective, non-randomized, before-after intervention study in an 18-bed ICU in Genoa, Italy. The intervention was a hospital antibiotic control policy and the observation was routine monitoring for nosocomial infections and antibiotic use, recording periodically the incidence density and MRSA prevalence. The intervention included a new antibiotic guideline that restricted the use of cephalosporins for all ICU inpatients. The analysis showed that the intervention determined a significant reduction in cephalosporin usage (-70.3%), while fluoroquinolones, mainly ciprofloxacin, increased after introduction of the antibiotic policy (+46.5%). A significant reduction in the percentage of MRSA infections (-30%) and heterogeneous susceptibility patterns in Klebsiella pneumoniae and Pseudomonas aeruginosa were noted.

Two time-series analyses of the impact of antibiotic consumption and alcohol-based hand disinfection on the incidences of nosocomial methicillin-resistant Staphylococcus aureus infection and Clostridium difficile infection

OBJECTIVE

To determine the impact of antibiotic consumption and alcohol-based hand disinfection on the incidences of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection and Clostridium difficile infection (CDI).

METHODS

Two multivariate time-series analyses were performed that used as dependent variables the monthly incidences of nosocomial MRSA infection and CDI at the Freiburg University Medical Center during the period January 2003 through October 2007. The volume of alcohol-based hand rub solution used per month was quantified in liters per 1,000 patient-days. Antibiotic consumption was calculated in terms of the number of defined daily doses per 1,000 patient-days per month.

RESULTS

The use of alcohol-based hand rub was found to have a significant impact on the incidence of nosocomial MRSA infection (P< .001). The multivariate analysis (R2=0.66) showed that a higher volume of use of alcohol-based hand rub was associated with a lower incidence of nosocomial MRSA infection. Conversely, a higher level of consumption of selected antimicrobial agents was associated with a higher incidence of nosocomial MRSA infection. This analysis showed this relationship was the same for the use of second-generation cephalosporins (P= .023), third-generation cephalosporins (P= .05), fluoroquinolones (P= .01), and lincosamides (P= .05). The multivariate analysis (R2=0.55) showed that a higher level of consumption of third-generation cephalosporins (P= .008), fluoroquinolones (P= .084), and/or macrolides (P= .007) was associated with a higher incidence of CDI. A correlation with use of alcohol-based hand rub was not detected.

CONCLUSION

In 2 multivariate time-series analyses, we were able to show the impact of hand hygiene and antibiotic use on the incidence of nosocomial MRSA infection, but we found no association between hand hygiene and incidence of CDI.

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.

Methicillin-resistant Staphylococcus aureus Control at the National University Hospital, Singapore: A Historical Perspective

Singapore has a sophisticated healthcare system and is an important referral centre for Asia. Like much of the world, methicillin-resistant Staphylococcus aureus (MRSA) is now endemic across its health system. MRSA infection has been associated with considerable attributable mortality, morbidity plus personal and public cost. Nosocomial infections are potentially preventable and need to be considered an unacceptable complication rather than a tolerable byproduct of healthcare. Failure to introduce long-term sustainable infection control initiatives is not an option for responsible clinical leaders and managers. Control of MRSA transmission in Singapore is achievable but we need to accept the challenge and acknowledge that it will take perhaps a decade. It requires implementation of many varied infection control measures to be rolled out sequentially and across all health services. Our ambition, in Singapore, should be for hospitals to achieve an inpatient prevalence of <1% MRSA colonised patients. Identified transmission of MRSA should be regarded as a serious breech. Successful control will require extraordinary collaboration, support, resources, accountability and consistency of effort. Currently, efforts are evolving significantly and today, we have a good opportunity to embark on this difficult journey. Implementing infection control initiatives successfully over the next few years will save lives in the future. Key words: Colonisation, Infection, Infection control

Methicillin-resistant Staphylococcus aureus Control in Singapore – Moving Forward

Singapore has a sophisticated healthcare system and is an important referral centre for Asia. Like much of the world, methicillin-resistant Staphylococcus aureus (MRSA) is now endemic across its health system. MRSA infection has been associated with considerable attributable mortality, morbidity plus personal and public cost. Nosocomial infections are potentially preventable and need to be considered an unacceptable complication rather than a tolerable byproduct of healthcare. Failure to introduce long-term sustainable infection control initiatives is not an option for responsible clinical leaders and managers. Control of MRSA transmission in Singapore is achievable but we need to accept the challenge and acknowledge that it will take perhaps a decade. It requires implementation of many varied infection control measures to be rolled out sequentially and across all health services. Our ambition, in Singapore, should be for hospitals to achieve an inpatient prevalence of <1% MRSA colonised patients. Identified transmission of MRSA should be regarded as a serious breech. Successful control will require extraordinary collaboration, support, resources, accountability and consistency of effort. Currently, efforts are evolving significantly and today, we have a good opportunity to embark on this difficult journey. Implementing infection control initiatives successfully over the next few years will save lives in the future. Key words: Colonisation, Infection, Infection control

Effect of antibiotics on the bacterial load of meticillin-resistant Staphylococcus aureus colonisation in anterior nares

Prevalence of hospital-acquired meticillin-resistant Staphylococcus aureus (MRSA) infection or colonisation has been associated with antimicrobial consumption. The impact of antibiotic treatment on nasal colonisation is unknown. We conducted a three-month prospective study of 116 patients with extranasal MRSA infection or colonisation, whose nasal MRSA bacterial loads were determined during and after various antibiotic courses over a period of three weeks. Environmental swabs were also taken from the near patient environment. Concomitant nasal MRSA carriage was observed in 76.7% of extranasal MRSA-colonised or -infected patients. The median nasal MRSA bacterial load increased significantly from 2.78 (range 0-6.15) to 5.30 (range 2.90-8.41) log(10) cfu per swab (cfu/swab) (P<0.001) over 21 days during beta-lactam therapy. It also increased from 0 (range 0-4.00) to 4.30 (range 0-7.46) log(10)cfu/swab (P=0.039) over 14 days during fluoroquinolone therapy. Median bacterial loads were significantly higher for beta-lactam- and fluoroquinolone-treated patients on day 7 [4.78, range 0-7.30], day 14 [4.30, range 0-7.60] and day 21 [5.30, range 2.90-8.41] than controls not receiving antibiotics (P<0.05). These loads then decreased by 2-5log(10)cfu/swab 2 weeks after discontinuation of antibiotics. The environment of patients receiving beta-lactam agents (relative risk: 3.55; 95% confidence interval: 1.30-9.62; P=0.018) or fluoroquinolones (4.32; 1.52-12.31; P=0.008) demonstrated more MRSA contamination than the environment around control patients (0.79; 0.67-0.93; P=0.002). Patients on beta-lactam or fluoroquinolone therapy have increased incidence of MRSA colonisation and higher nasal bacterial loads, and appear to spread their MRSA into the near patient environment.

Modelling the impact of antibiotic use and infection control practices on the incidence of hospital-acquired methicillin-resistant Staphylococcus aureus: a time-series analysis

OBJECTIVES

Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide. A wide range of factors have been suggested to influence the spread of MRSA. The objective of this study was to evaluate the effect of antimicrobial drug use and infection control practices on nosocomial MRSA incidence in a 426-bed general teaching hospital in Northern Ireland.

METHODS

The present research involved the retrospective collection of monthly data on the usage of antibiotics and on infection control practices within the hospital over a 5 year period (January 2000-December 2004). A multivariate ARIMA (time-series analysis) model was built to relate MRSA incidence with antibiotic use and infection control practices.

RESULTS

Analysis of the 5 year data set showed that temporal variations in MRSA incidence followed temporal variations in the use of fluoroquinolones, third-generation cephalosporins, macrolides and amoxicillin/clavulanic acid (coefficients = 0.005, 0.03, 0.002 and 0.003, respectively, with various time lags). Temporal relationships were also observed between MRSA incidence and infection control practices, i.e. the number of patients actively screened for MRSA (coefficient = -0.007), the use of alcohol-impregnated wipes (coefficient = -0.0003) and the bulk orders of alcohol-based handrub (coefficients = -0.04 and -0.08), with increased infection control activity being associated with decreased MRSA incidence, and between MRSA incidence and the number of new patients admitted with MRSA (coefficient = 0.22). The model explained 78.4% of the variance in the monthly incidence of MRSA.

CONCLUSIONS

The results of this study confirm the value of infection control policies as well as suggest the usefulness of restricting the use of certain antimicrobial classes to control MRSA.

Analysis of meticillin-susceptible and meticillin-resistant biofilm-forming Staphylococcus aureus from catheter infections isolated in a large Italian hospital

Several characteristics were analysed in 37 Staphylococcus aureus isolates from nosocomial catheter infections: the PFGE profile after SmaI digestion of chromosomal DNA, the ability to form a biofilm on a polystyrene surface, antibiotic susceptibility patterns (penicillin, oxacillin, erythromycin, tetracycline, clindamycin, telithromycin, gentamicin, ciprofloxacin, quinupristin/dalfopristin, rifampicin, vancomycin and linezolid), and the presence of genetic determinants of antibiotic resistance and biofilm formation. All strains but three (92 %) were able to grow on a plastic surface as a biofilm. An almost complete association was found between phenotypes and genotypic traits of antibiotic resistance, whilst PFGE profiling showed the highly polyclonal composition of the set of strains under study. Sixteen isolates (43 %) were meticillin-resistant and were subjected to staphylococcal cassette chromosome mec (SCCmec) and cassette chromosome recombinase (ccr) complex type determination by multiplex PCR. Only a subgroup of six strains belonged to the archaic clone PFGE type and bore the SCCmec/ccrAB type I structure. Among the remaining strains some presented small rearrangements of the SCCmec/ccrAB genetic locus, whilst others could barely be traced back to a known structural type. These observations suggest that, at the local level and at a particular site of infection, S. aureus may show great genetic variability and escape the general rule of expansion of the S. aureus pandemic clones.

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.

Relationship between rates of antimicrobial consumption and the incidence of antimicrobial resistance in Staphylococcus aureus and Pseudomonas aeruginosa isolates from 47 French hospitals

OBJECTIVE

To investigate relationships between rates of antimicrobial consumption and the incidence of antimicrobial resistance in Staphylococcus aureus and Pseudomonas aeruginosa isolates from hospitals.

METHODS

We conducted an observational study that used retrospective data from 2002 and linear regression to model relationships. Hospitals were asked to collect data on consecutive S. aureus and P. aeruginosa isolates, consumption rates for antibiotics (ie, anti-infectives for systemic use as defined by Anatomical Therapeutic Chemical class J01), and hospital characteristics, including infection control policies. Rates of methicillin resistance in S. aureus and rates of ceftazidime and ciprofloxacin resistance in P. aeruginosa were expressed as the percentage of isolates that were nonsusceptible (ie, either resistant or intermediately susceptible) and as the incidence of nonsuceptible isolates (ie, the number of nonsuceptible isolates recovered per 1,000 patient-days). The rate of antimicrobial consumption was expressed as the number of defined daily doses per 1,000 patient-days.

SETTING

Data were obtained from 47 French hospitals, and a total of 12,188 S. aureus isolates and 6,370 P. aeruginosa isolates were tested.

RESULTS

In the multivariate analysis, fewer antimicrobials showed a significant association between the consumption rate and the percentage of isolates that were resistant than an association between the consumption rate and the incidence of resistance. The overall rate of antibiotic consumption, not including the antibiotics used to treat methicillin-resistant S. aureus infection, explained 13% of the variance between hospitals in the incidence of methicillin resistance among S. aureus isolates. The incidence of methicillin resistance in S. aureus isolates increased with the use of ciprofloxacin and levofloxacin and with the percentage of the hospital's beds located in intensive care units (adjusted multivariate coefficient of determination [aR(2)], 0.30). For P. aeruginosa, the incidence of ceftazidime resistance was greater in hospitals with higher consumption rates for ceftazidime, levofloxacin, and gentamicin (aR(2), 0.37). The incidence of ciprofloxacin resistance increased with the use of fluoroquinolones and with the percentage of a hospital's beds located in intensive care ( aR(2), 0.28).

CONCLUSIONS

A statistically significant relationship existed between the rate of fluoroquinolone use and the rate of antimicrobial resistance among S. aureus and P. aeruginosa isolates. The incidence of resistant isolates showed a stronger association with the rate of antimicrobial use than did the percentage of isolates with resistance.

Rapid spread of methicillin-resistant Staphylococcus aureus in a new hospital in the broad-spectrum antibiotic era

OBJECTIVES

It has been known that it takes a long time for methicillin-resistant Staphylococcus aureus (MRSA) to introduce and become endemic within a hospital. During the last decade, widespread use of broad-spectrum antibiotics might have affected the time required for MRSA to spread and become endemic in hospitals. However, there has been no report on this issue. We investigated how fast MRSA has spread and become endemic in a hospital opened in the broad-spectrum antibiotic era.

METHODS

The study was performed at a Korean hospital, which opened in 1999. We examined the change of antimicrobial susceptibility and antimicrobial use density (AUD) for 6 years since hospital opening.

RESULTS

S. aureus susceptibility to oxacillin decreased from 64% in the first month to 33% in the second month (P=.05), and then has maintained around 30%. AUD was remarkably high from the first year, in which total AUD and those of aminopenicillins, second-generation cephalosporins, fluoroquinolones, and macrolides were 4674.6, 1444.6, 1700.9, 421.3, and 520.0 DDD/1000 patient-days, respectively.

CONCLUSIONS

MRSA has spread within a few months in a hospital opened in the broad-spectrum antibiotic era. Excessively high use of broad-spectrum antibiotics seems to be responsible for rapid spread of MRSA in the hospital.

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.

Multidrug-resistant bacteria in hospitalized children: a 5-year multicenter study

OBJECTIVE

The objective of this study was to determine the incidence of multidrug-resistant bacteria in hospitalized children.

METHODS

This multicenter study was conducted in 5 hospitals in the Paris area from 1999 to 2003. We recorded all isolations of multidrug-resistant bacteria from clinical samples that were obtained from hospitalized children. Strains that were isolated during systematic screening for carriers were excluded.

RESULTS

The mean incidences were 0.9 per 1000 hospitalization-days for methicillin-resistant Staphylococcus aureus, 0.45 for extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, 0.32 for extended-spectrum beta-lactamase-producing Enterobacteriaceae other than Klebsiella pneumoniae, 0.40 for Enterobacter species with derepressed cephalosporinase, and 0.01 for vancomycin-resistant Enterococcus. The incidences per 1000 hospitalization-days of methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, extended-spectrum beta-lactamase-producing Enterobacteriaceae other than Klebsiella pneumoniae, and Enterobacter species with derepressed cephalosporinase decreased significantly from 1999 to 2003, whereas the incidence of vancomycin-resistant Enterococcus remained very low. The proportion of resistant strains within the species did not vary significantly for methicillin-resistant Staphylococcus aureus (11% to 9.6%), extended-spectrum beta-lactamase-producing Enterobacteriaceae other than Klebsiella pneumoniae (1.1%), and vancomycin-resistant Enterococcus (0.03% to 0.023%). In contrast, the frequency of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae decreased from 31.6% to 7.4%, and that of Enterobacter species with derepressed cephalosporinase decreased from 38.8% to 18.5%.

CONCLUSIONS

We report significant decreases in the incidence of methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, extended-spectrum beta-lactamase-producing Enterobacteriaceae other than Klebsiella pneumoniae, and Enterobacter species with derepressed cephalosporinase in hospitalized children during a 5-year period.

Antimicrobial drug use and infection control practices associated with the prevalence of methicillin-resistant Staphylococcus aureus in European hospitals

Major regional variations in the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) are observed across Europe. This study investigated hospital MRSA prevalence in relation to patterns of antimicrobial use and infection control policies in an observational, cross-sectional study that used retrospective data from 2001 and linear regression to model relationships. MRSA prevalence (median 20.8%, n = 173 hospitals) and antimicrobial consumption (median 55.2 defined daily doses/100 bed-days, n = 140 hospitals) both varied significantly according to geographical region (p <0.001). MRSA prevalence and antimicrobial consumption data were provided by 128 hospitals, and showed a strong statistical relationship between macrolide use and MRSA prevalence. Use of (i) third-generation cephalosporins, (ii) all antimicrobial agents, and (iii) all antimicrobial agents except glycopeptides was also associated with MRSA prevalence. Up to 146 hospitals provided data on MRSA prevalence and key infection control parameters. Adjusted linear regression modelling provided strong evidence that infection control policy recommendations associated with lower MRSA prevalence rates were (i) use of alcohol-based solutions for hand hygiene (mean difference 10.3%, 99% CI 1.2-10.3), and (ii) placement of MRSA patients in single rooms (mean difference 11.2%, 99% CI 1.4-20.9). Hospitals with problems in implementing isolation policies had higher resistance levels (mean difference 12%, 99% CI 3.8-20.1). Additional recommendations showed less evidence of association with a low MRSA prevalence. Overall, this study highlighted significant associations between MRSA prevalence, antimicrobial use and various key infection control parameters, all of which showed significant individual variations according to geographical region.

Staphylococcus aureus strains isolated from bloodstream infections changed significantly in 2006

We studied 358 Staphylococcus aureus strains isolated from bloodstream infections (BSI) observed during an epidemiological study covering 2,007,681 days of hospitalization in 32 healthcare institutions (HCIs) between 2004 and 2006. The strains were tested for antibiotic susceptibility and characterized genetically. The incidence of S. aureus BSI declined regularly through 2004 and 2005 and then significantly increased in 2006 (+80%). This was largely due to an increase in BSI involving methicillin-sensitive S. aureus (MSSA) strains and nonmultiresistant methicillin-resistant S. aureus (NORSA) strains. Ninety-six percent of the NORSA strains were resistant only to methicillin and fluoroquinolones. Most of the MSSA strains belonged to a small number of pulsed-field gel electrophoresis (PFGE) divisions and were associated with epidemic phenomena in HCIs. The NORSA strains also clustered into a limited number of PFGE divisions but could not be related to any local outbreak in HCIs. In 2006, there was a significant increase in the incidence of BSI associated with tst gene-positive MSSA strains (+275%) and the first three BSI associated with tst gene-positive MRSA were observed. PFGE data revealed a limited heterogeneity among the tst gene-positive strains without any outbreak in the HCIs. Our study underlines the need for infection control teams to focus efforts on preventing both MRSA and MSSA BSI. As recently demonstrated in vitro, fluoroquinolones may enhance horizontal transfer of virulence and antibiotic resistance genes. These antibiotics are widely used in France, so our findings raise the issue of whether their use has contributed to the acquisition of mecA and tst genes by S. aureus strains.

Effect of reduction in ciprofloxacin use on prevalence of meticillin-resistant Staphylococcus aureus rates within individual units of a tertiary care hospital

Previous studies have shown a correlation between fluoroquinolone use in hospitals and rates of meticillin-resistant Staphylococcus aureus (MRSA) infection. This study examined the effect on MRSA infection rates within individual adult units of a tertiary care teaching hospital after instituting a programme to decrease ciprofloxacin use. Clinical specimens positive for S. aureus were determined on all adult inpatient units between 1 January 2004 and 31 December 2005. Units with >10 isolates of S. aureus per year were included in the analysis. Ciprofloxacin use, measured in defined daily doses per 1000 patient-days, was determined for each unit during the same time period. Ciprofloxacin use and MRSA rates for 2004 and 2005 were compared. In the 17 units studied, ciprofloxacin use decreased by 31.2% (P<0.0001). The MRSA rate in these units decreased from 59.6% to 54.2% (P=0.122). There was a correlation between ciprofloxacin use and the MRSA rate within these units (r=0.70; 95% confidence interval -0.01-0.94; P=0.053). Within individual units, there was a variable response. In seven of the units, there was an increase in the MRSA rate despite a reduction in ciprofloxacin use, suggesting that other factors (length of stay, infection control and community-acquired MRSA) may have contributed. Although many factors are associated with high MRSA rates, ciprofloxacin use appears to be a contributing factor. Reducing the use of ciprofloxacin may be a means of controlling MRSA in the hospital setting.

Duration of methicillin-resistant Staphylococcus aureus carriage, according to risk factors for acquisition

OBJECTIVE

To examine the duration of methicillin-resistant Staphylococcus aureus (MRSA) carriage and its determinants and the influence of eradication regimens.

DESIGN

Retrospective cohort study.

SETTING

A 1,033-bed tertiary care university hospital in Bern, Switzerland, in which the prevalence of methicillin resistance among S. aureus isolates is less than 5%.

PATIENTS

A total of 116 patients with first-time MRSA detection identified at University Hospital Bern between January 1, 2000, and December 31, 2003, were followed up for a mean duration of 16.2 months.

RESULTS

Sixty-eight patients (58.6%) cleared colonization, with a median time to clearance of 7.4 months. Independent determinants for shorter carriage duration were the absence of any modifiable risk factor (receipt of antibiotics, use of an indwelling device, or presence of a skin lesion) (hazard ratio [HR], 0.20 [95% confidence interval {CI}, 0.09-0.42]), absence of immunosuppressive therapy (HR, 0.49 [95% CI, 0.23-1.02]), and hemodialysis (HR, 0.08 [95% CI, 0.01-0.66]) at the time MRSA was first MRSA detected and the administration of decolonization regimen in the absence of a modifiable risk factor (HR, 2.22 [95% CI, 1.36-3.64]). Failure of decolonization treatment was associated with the presence of risk factors at the time of treatment (P=.01). Intermittent screenings that were negative for MRSA were frequent (26% of patients), occurred early after first detection of MRSA (median, 31.5 days), and were associated with a lower probability of clearing colonization (HR, 0.34 [95% CI, 0.17-0.67]) and an increased risk of MRSA infection during follow-up.

CONCLUSIONS

Risk factors for MRSA acquisition should be carefully assessed in all MRSA carriers and should be included in infection control policies, such as the timing of decolonization treatment, the definition of MRSA clearance, and the decision of when to suspend isolation measures.

Using interrupted time series analysis to assess associations of fluoroquinolone formulary changes with susceptibility of gram-negative pathogens and isolation rates of methicillin-resistant Staphylococcus aureus

The use of fluoroquinolones has been linked to increasing bacterial resistance and infection and/or colonization with already resistant pathogens both as a risk factor and based on volume of use. Changes in individual fluoroquinolones used in an institution may also be related to these clinical problems. Interrupted time series analysis, which allows for assessment of the associations of an outcome attributable to a specific event in time, was used to study the effect of changes in our hospital's fluoroquinolone formulary on fluoroquinolone susceptibility rates in select gram-negative pathogens and the methicillin-resistant Staphylococcus aureus (MRSA) isolation rate. Susceptibility rates to ciprofloxacin were considered for the period of 1993 through 2004, while the MRSA isolation rate was assessed from 1995 through 2004. Levofloxacin was added to the formulary in 1999, and gatifloxacin was substituted for levofloxacin in 2001. Statistically significant changes in the already declining rates of susceptibility of Pseudomonas aeruginosa (P, 0.042) and Escherichia coli (P, 0.004) to ciprofloxacin and in the already rising MRSA isolation rate (P, 0.001) were associated with the addition of levofloxacin to the formulary. Substitution of gatifloxacin for levofloxacin on the formulary was associated with reversals in the downward trend in E. coli susceptibility to ciprofloxacin and the upward trend in MRSA isolation rate. No associations were detected on susceptibility of Klebsiella pneumoniae or Proteus mirabilis to ciprofloxacin. These findings suggest that potential changes in susceptibility to fluoroquinolones and isolation of MRSA may vary by both drug and organism.

Guidelines for the control and prevention of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

Meticillin-resistant Staphylococcus aureus (MRSA) remains endemic in many UK hospitals. Specific guidelines for control and prevention are justified because MRSA causes serious illness and results in significant additional healthcare costs. Guidelines were drafted by a multi-disciplinary group and these have been finalised following extensive consultation. The recommendations have been graded according to the strength of evidence. Surveillance of MRSA should be undertaken in a systematic way and should be fed back routinely to healthcare staff. The inappropriate or unnecessary use of antibiotics should be avoided, and this will also reduce the likelihood of the emergence and spread of strains with reduced susceptibility to glycopeptides, i.e. vancomycin-intermediate S. aureus/glycopeptide-intermediate S. aureus (VISA/GISA) and vancomycin-resistant S. aureus (VRSA). Screening for MRSA carriage in selected patients and clinical areas should be performed according to locally agreed criteria based upon assessment of the risks and consequences of transmission and infection. Nasal and skin decolonization should be considered in certain categories of patients. The general principles of infection control should be adopted for patients with MRSA, including patient isolation and the appropriate cleaning and decontamination of clinical areas. Inadequate staffing, especially amongst nurses, contributes to the increased prevalence of MRSA. Laboratories should notify the relevant national authorities if VISA/GISA or VRSA isolates are identified.

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.

Evaluation of an intervention designed to decrease the rate of nosocomial methicillin-resistant Staphylococcus aureus infection by encouraging decreased fluoroquinolone use

OBJECTIVE

Society for Health Care Epidemiology guidelines recommend decreasing the use of fluoroquinolone antibiotics in institutions where methicillin-resistant Staphylococcus aureus (MRSA) is endemic. We evaluated whether an intervention to limit fluoroquinolone use was associated with a lower rate of nosocomial MRSA infection and summarized changes in antibiotic use, changes in other variables potentially correlated with a lower rate of MRSA infection, and rates of nosocomial infections due to other pathogens.

DESIGN

Single-center quasi-experimental design. A time series of nosocomial MRSA infections was measured at monthly intervals from July 2001 through June of 2004; there were 80 MRSA infections recorded. Segmented regression analysis (ie, quasi-Poisson generalized linear models) was used to evaluate variables possibly associated with the nosocomial MRSA infection rate.

SETTING

An 87-bed Veterans Affairs teaching hospital with an extended-care facility.

INTERVENTION

A physician-directed computer-generated intervention designed to limit the use of fluoroquinolone antibiotics was initiated, and institutional changes in antibiotic use and nosocomial MRSA infection rates were tracked.

RESULTS

After the intervention, fluoroquinolone use decreased by approximately 34%, and levofloxacin use decreased by approximately 50%. Decreased fluoroquinolone use was offset by increased cephalosporin, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole use. The nosocomial MRSA infection rate decreased from 1.37 to 0.63 episodes per 1,000 patient-days after the study intervention (P=.02). Coagulase-negative Staphylococcus and Enterococcus infection rates also decreased. However, the rate of infection with gram-negative organisms increased. The rate of MRSA infection was positively correlated with levofloxacin use (P=.01) and azithromycin use (P=.08), whereas it was negatively correlated with summer season (P=.05). In a subsequent model, the rate of MRSA infection was negatively correlated with the study intervention (P=.04).

CONCLUSION

Reduction in the institutional use of fluoroquinolones may be associated with a lower nosocomial MRSA infection rate.

Fluoroquinolone use and methicillin-resistant Staphylococcus aureus isolation rates in hospitalized patients: a quasi experimental study

BACKGROUND

We investigated the possible association between fluoroquinolone use and the rate of methicillin-resistant Staphylococcus aureus (MRSA) recovery from consecutive hospitalized patients.

METHODS

We conducted a nonrandomized, prospective, controlled interventional "fluoroquinolone-free" study at 4 large teaching hospitals in northwest France, catering to a total of 5,882,600 persons. During the intervention period (January through December 2001), fluoroquinolone use was prohibited at 1 of the 4 hospitals (Caen Hospital), unless no effective alternative was available. Three university hospitals were used as controls because they had similar preintervention rates of MRSA.

RESULTS

During the intervention period (2001), the annual rate of fluoroquinolone use decreased from 54 to 5 defined daily doses per 1000 patients per day at Caen Hospital and remained stable in the control hospitals. At the end of the intervention, the rate of MRSA isolation was significantly lower at Caen Hospital than at the control hospitals (353 [32.3%] of 1093 S. aureus isolates were MRSA, compared with 2495 [36.8%] of 6787 isolates; odds ratio, 0.82; 95% confidence interval, 0.69-0.99; P=.036), as determined on the basis of a marginal model that took into account within-hospital clustering. In a before-after time series analysis, compared with forecasted rates, there was a significant downward trend in observed monthly rates of MRSA isolation at Caen Hospital at the end of the intervention.

CONCLUSION

This quasi experimental study confirms the association between fluoroquinolone use and MRSA isolation among hospitalized patients.

Tigecycline and the Need for a New Broad-Spectrum Antibiotic Class

BACKGROUND

Lack of progress in developing new antimicrobials, particularly new classes, as opposed to variants of existing agents, has contributed to the emergence of antibiotic-resistant pathogens.

METHODS

Data synthesis after review of pertinent English-language literature.

RESULTS

The development of new classes of antimicrobial agents is crucial, considering the increasing prevalence of nosocomial pathogens resistant to empiric as well as second- and third-line antibiotic choices. Tigecycline has recently been approved for the treatment of complicated skin and skin structure as well as intra-abdominal infections. Published data on the in vitro and in vivo properties of tigecycline, the first-in-class glycylcycline, are reviewed.

CONCLUSION

It is plausible that tigecycline could to some extent replace available broadspectrum agents for approved indications and thereby reduce the selective pressure for some currently prevalent multi-resistant pathogens in the hospital setting.