Aumento significativo de la colonización por Staphylococcus aureus entre los estudiantes de medicina durante la realización de las prácticas en el hospital

Introduction

Staphylococcus aureus is a pathogen of major concern. The emergence of methicillin-resistant S. aureus (MRSA) has increasingly complicated the therapeutic approach of hospital-acquired infections. Surveillance of MRSA and control measures must be implemented in different healthcare settings, including screening programs for carriers. Our first aim was to determine the prevalence of methicillin-susceptible S. aureus (MSSA) and MRSA nasal carriage in medical students from the Clínico San Carlos Hospital (Madrid). As the MRSA carrier rate in healthcare workers is higher than in the general population, we hypothesised that carrier rate could be increased during their clinical practice in their last three years.

Methods

We performed an epidemiologic al study of the prevalence of S. aureus colonisation among a group of medical students, who were sampled in 2008 in their third-year, and in 2012 when this class was in its sixth year.

Results

We have found a significant increase in MSSA carriage, from 27% to 46%. There were no MRSA colonisations in the third-year, but one was found in the sixth-year group. The large majority of strains (89%) of strains were resistant to penicillin, and 27% to erythromycin and clindamycin. As 19 coagulase-negative Staphylococcus MR were also identified, a horizontal transfer of genes, such as mecA gene to S. aureus, could have occurred.

Conclusions

Medical students are both, at risk for acquiring, and a potential source of nosocomial pathogens, mainly MSSA. Therefore, they should take special care for hygienic precautions, such as frequent and proper hand washing, while working in the hospital.     

Caracterización molecular de cepas de Staphylococcus aureus resistentes a meticilina ST398 en pacientes con infecciones cutáneas y sus familiares

Introduction

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of sequence type ST398 is a genetic lineage also described in human infections.

Methods

Cutaneous infections related with MRSA ST398 are described in 3 patients, two of them pig farmers. The MRSA nasal carriage by patients and their relatives was also studied. MRSA ST398 strains were typed (SCCmec, spa, agr and MLST) and the antimicrobial resistance pattern and virulence genes were determined.

Results

Twenty MRSA ST398 isolates were recovered in lesions of three patients, and in nasal samples of two patients and five relatives. Isolates were typed: spa-type t011 or t108; agr-type I and SCCmec IVa or V. MRSA strains were tetracycline-resistant and 15 of them showed a phenotype and genotype of multi-resistance, but they were free of tested virulence genes.

Conclusions

LA-MRSA ST398 is an emergent problem in our country, mainly associated with skin and soft tissue infections in people with professional relationships with pig farms. Tetracycline resistance is an important marker for MRSA ST398 detection.     

Características clínicas y pronóstico de la neumonía adquirida en la comunidad causada por Staphylococcus aureus resistente a la meticilina

Introduction

The aim of this study is to describe the epidemiological and clinical features, treatment and prognosis of community-acquired pneumonia (CAP) caused by methicillin-resistant Staphylococcus aureus (MRSA) in two different geographic regions where community-acquired MRSA (CA-MRSA) infections have different frequencies.

Methods

Observational study of patients admitted to two hospitals (one in Argentina, the other in Spain) between March 2008 and June 2012.

Results

We documented 16 cases of CAP caused by MRSA. MRSA accounted for 15 of 547 (2.7%) cases of CAP in Hospital Rodolfo Rossi and 1 of 1258 (0,08%) cases at the Hospital Universitari de Bellvitge (P ≤ .001). Most patients were young and previously healthy. Multilobar infiltrates, cavitation and skin and soft tissue involvement were frequent. All patients had positive blood cultures. Five patients required admission to the intensive care unit. Early mortality (≤ 48 hours) was 19%, and overall mortality (≤ 30 days) was 25%.

Conclusion

CAP caused by MRSA causes high morbidity and mortality rates. It should be suspected in areas with a high prevalence of CA-MRSA infections, and especially in young and healthy patients who present with multilobar pneumonia with cavitation. Mortality is mainly related to septic shock and respiratory failure and occurs early in most cases.     

Infecciones neonatales por Staphylococcus aureus de inicio en la comunidad

Introduction

Staphylococcus aureus is a major cause of neonatal community-onset infections. The emergence of methicillin-resistant S. aureus infections in this age group has been reported in USA in the last few years; however there are no studies in Spain. The aim of this study is to describe the epidemiological, clinical and microbiological characteristics of S. aureus community-onset infections in neonates.

Methods

We prospectively reviewed the S. aureus infections in neonates over a three year period (2007-2009) in the Pediatric Emergency Department of Hospital 12 de Octubre in Madrid (Spain).

Results

We recorded 30 cases of neonatal S. aureus community-onset infections. Only one isolated (3.3%) was resistant to methicillin, and two (6.7%) were PVL(+).

Conclusions

Despite the emergence of MRSA outside the hospital in pediatric population in Spain, CA-MRSA and SA PVL(+) infections are not frequent in neonates.     

Significado clínico del aislamiento de Staphylococcus aureus en muestras de orina

Introduction

To evaluate the clinical significance of the isolation of Staphylococcus aureus in urine samples.

Methods

A retrospective study was performed on adult patients identified from a microbiology database in a 200-bed general hospital between the years 2000 and 2009. The demographic data, comorbidities, and risk factors, were reviewed, particularly those associated with the concomitant isolation of S. aureus in blood cultures.

Results

The frequency of S. aureus found in urine samples was 0.63%. A total of 43 patients (mean age 68.7 years [SD ± 16], and 58.1% males) were identified in the database. A Charlson comorbidity index > 3 was observed in 20.9%. Concurrent bacteremia was seen in 48.8%. Two groups of patients were distinguished: with concomitant bacteremia (n = 21) or without (n = 22). Intervention in the urinary tract significantly predicted (P = .00004) bacteriuria without bacteremia (81.8%), compared to bacteremia cases (19%). The attributable mortality was 47.6% in patients with bacteremia compared to non-bacteremia (no deaths), even though the appropriate antibiotic treatment was more frequent among patients with bacteremia (92% and 60%, respectively).

Conclusion

The presence of S. aureus in urine was accompanied by bacteremia in half of the cases, but in patients without previous urinary tract intervention such a possibility increased to 81%. Concomitant bacteremia predicts a worse prognosis even with appropriate treatment.     

Infecciones de piel y partes blandas en pacientes hospitalizados: factores epidemiológicos,microbiológicos,clínicos y pronósticos

Introduction

Skin and soft-tissue infections (SSTIs) are a frequent cause of consultation in emergence services, and complicated cases require hospitalization. However there are few data in our setting about the clinical characteristics of these infections.

Material and methods

A retrospective review of hospital admitted patients with a diagnosis of folliculitis, cellulitis, erysipelas, abscesses, hidradenitis, furuncle, impetigo, fasciitis and Fournier's gangrene. Cases were extracted from the data base of diagnostic codes of the Archive and Clinical Documentation Department of Son Llàtzer Hospital from January 2002 to November 2011.

Results

We studied 996 episodes in 841 hospitalized patients with any diagnosis of SSTIs. Cellulitis/erysipelas (66.7%) was the most frequently diagnosed condition, with 77% of all SSTIs being community acquired, and the majority of patients had comorbidities, mainly diabetes (33%) and heart failure (17.7%). The most frequent isolated microorganism was S. aureus (35.1%), in 19 (12.9%) cases with methicillin-resistance (MRSA), 84.2% of them were nosocomial or health care acquired. Monotherapy with aminopenicillin with clavulanic acid was the empiric treatment most frequently used (35.5%). New antibiotics for Gram-positive cocci (linezolid, daptomycin, and tigecycline) were used in patients with comorbidities that presented more complications (P < .001) and more risk of mortality (P = .001). During admission 10.9% of patients died, but only in 2.7% of them mortality was related to the SSTIs.

Conclusions

SSTIs attended most frequently in hospitalized patients are mainly cellulitis/erysipela, the majority community acquired. MRSA infections are mainly health care related. Use of new antibiotic for Gram-positive cocci was limited.     

Fifteen-year study of the changing epidemiology of methicillin-resistant Staphylococcus aureus

Purpose

The study’s purpose was to elucidate the evolutionary, microbiologic, and clinical characteristics of methicillin-resistant Staphylococcus aureus (MRSA) infections.

Methods

MRSA cases from military medical facilities in San Diego, from 1990 to 2004, were evaluated and categorized as community-acquired or nosocomial. Sequence type, staphylococcal chromosomal cassette gene type, and Panton-Valentine leukocidin gene status were determined for a subset of isolates.

Results

Over the 15-year period, 1888 cases of MRSA were identified; 65% were community acquired. The incidence (155 infections/100 000 person-year in 2004) and household-associated cases rapidly increased since 2002. Among persons with community-acquired MRSA, 16% were hospitalized and only 17% were initially given an effective antibiotic. Community-acquired MRSA cases compared with nosocomial MRSA cases were more often soft-tissue and less often urinary, lung, or bloodstream infections (P < .001). Patients with community-acquired MRSA were younger (22 vs 64 years, P < .001) and less likely to have concurrent medical conditions (9% vs 98%, P < .001). Clindamycin resistance increased among community-acquired MRSA isolates during 2003 and 2004 compared with previous years (79% vs 13%, P < .001). Genetically, nosocomial MRSA isolates were significantly different than those acquired in the community. Although community-acquired MRSA isolates were initially diverse by 2004, one strain (staphylococcal chromosomal cassette type IV, sequence type 8, Panton-Valentine leukocidin gene positive) became the predominant isolate.

Conclusions

Community-acquired and intrafamilial MRSA infections have increased rapidly since 2002. Our 15 years of surveillance revealed the emergence of distinct community-acquired MRSA strains that were genetically unrelated to nosocomial MRSA isolates from the same community.     

Staphylococcus aureus resistente a la meticilina y a descolonizadores habituales con reservorio en un trabajador sanitario en un hospital de tercer nivel

Background

Methicillin-resistant Staphylococcus aureus (MRSA) has become an important hospital-acquired pathogen, with transfer of the organism from a carrier or infected patient to uninfected patients by the hands or clothing of staff as the main mode of transmission.

Methods

Investigation of a cluster of new cases of MRSA resistant to mupirocin and fusidic acid, using epidemiological and microbiological resources.

Results

From September 2010 to February 2012, sixteen patients had at least one culture positive for MRSA resistant to mupirocin and fusidic acid. Some not apparently related cases and outbreaks appeared. By analysing cultures taken from patients and staff using pulsed-field gel electrophoresis, it was demonstrated that most likely this situation was started by an auxiliary nurse who was a carrier of the MRSA. Healthcare worker decontamination using oral antibiotic therapy was unsuccessful. Eventually, the situation was controlled by placing the carrier in a different job, with no further cases to date (September, 2012).

Conclusion

This report illustrates the risk of nosocomial transmission linked to care delivered by healthcare workers.     

Erradicación de un brote nosocomial de infecciones por Acinetobacter baumannii multirresistente tras el ajuste de cargas de trabajo y refuerzo de precauciones específicas

Introduction

During 2009, an outbreak of multidrug-resistant Acinetobacter baumannii (MDR A. baumannii) infections was detected in a 27-bed intensive care unit, resulting in 25 cases being infected.

Methods

A matched case-control study was conducted to identify risk factors for infection. The colonization pressure, or the proportion of other patients colonized by MDR A. baumannii, was estimated. TISS-28 and Omega scores of each patient were calculated to evaluate nursing work requirements. Conditional logistic regression analyses were carried out.

Results

Breakdowns in hand washing and glove use were observed. Infected patients (cases) were more likely than paired controls to have had longer exposure to invasive devices and antimicrobial treatment. The independent risk factors identified by the multivariate analysis were, mechanical ventilation [odds ratio (OR) = 1.03; 95% confidence interval (CI), 1.01-1.05; P = .01], and exposure to an infected or colonized patient [OR = 1.7; 95% CI, 1.1-2.6; P = .02). A combined infection control strategy was implemented, including strict compliance with isolation precautions, grouping of patients, reinforcing cleaning and disinfection of surfaces, and a decrease in work load. Subsequently, a sharp reduction in the incidence MDR A. baumannii infections was shown. Therapeutic activity scores were significantly higher for cases than for controls.

Conclusion

The results suggest patient-to-patient transmission of MDR A. baumannii. Reinforcement of specific procedures and work load adjustment were essential to eradicate this outbreak.     

Análisis combinado de dos ensayos aleatorizados de comparación de stents con recubrimiento de titanio-óxido nítrico con stents liberadores de fármacos en el IAMCEST

Introduction and objectives

We performed a pooled analysis based on patient-level data from the TITAX-AMI and BASE-ACS trials to evaluate the outcome of titanium-nitride-oxide-coated bioactive stents vs drug-eluting stents in patients with ST-segment elevation myocardial infarction at 2-year follow-up.

Methods

The TITAX-AMI trial compared bioactive stents with paclitaxel-eluting stents in 425 patients with acute myocardial infarction. The BASE-ACS trial compared bioactive stents with everolimus-eluting stents in 827 patients with acute coronary syndrome. The primary endpoint for the pooled analysis was major adverse cardiac events: a composite of cardiac death, recurrent myocardial infarction, or ischemia-driven target lesion revascularization at 2-year follow-up.

Results

The pooled analysis included 501 patients; 245 received bioactive stents, and 256 received drug-eluting stents. The pooled bioactive stent group was associated with a risk ratio of 0.85 for major adverse cardiac events (95% confidence interval, 0.53-1.35; P = .49) compared to the pooled drug-eluting stent group. Similarly, the pooled bioactive stent group was associated with a risk ratio of 0.71 for cardiac death (95% confidence interval, 0.26-1.95; P = .51), 0.44 for recurrent myocardial infarction (95% confidence interval, 0.20-0.97; P = .04), and 1.39 for ischemia-driven target lesion revascularization (95% confidence interval, 0.74-2.59; P = .30), compared to the pooled drug-eluting stent group. These results were confirmed by propensity-score adjusted analysis of the combined datasets.

Conclusions

In patients with ST-segment elevation myocardial infarction, bioactive stents were associated with lower rates of recurrent myocardial infarction compared to drug-eluting stents at 2-year follow-up; yet, the rates of cardiac death and ischemia-driven target lesion revascularization were similar.Full English text available from: www.revespcardiol.org/en     

Evaluating the probability of previously unknown carriage of MRSA at hospital admission

Purpose

We determined the prevalence and risk profile of patients with previously unknown carriage of methicillin-resistant Staphylococcus aureus (MRSA) at hospital admission.

Subjects and methods

We conducted a 7-month, prospective case-controlled study in adult inpatients admitted to a university hospital with endemic MRSA. Multivariate conditional logistic regression for data sets matched 1:4 was performed to identify the risk profile of newly identified MRSA carriers.

Results

Overall, 399 of 12 072 screened admissions (prevalence, 3.3%) were found colonized (n = 368, 92%) or infected (n = 31, 8%) with MRSA. In 204 cases (prevalence, 1.7%), MRSA carriage was newly identified. Without screening on admission, 49% (196/399) of MRSA carriers would have been missed. We identified nine independent risk factors for newly identified MRSA carriage at admission (adjusted odds ratio): male sex (1.9); age greater than 75 years (2.0); receipt of fluoroquinolones (2.7), cephalosporins (2.1), and carbapenems (3.2) in the last 6 months; previous hospitalization (1.9) or intravenous therapy (1.7) during the last 12 months; urinary catheter at admission (2.0); and intrahospital transfer (2.4). A risk score (range, 0-13) was calculated by adding points assigned to these variables. On the basis of analysis of 1006 patients included in the case-controlled study, the probability of MRSA carriage was 8% (28/342) in patients with a low score (≤1), 19% (92/482) in patients with an intermediate score (2-4), and 46% (84/182) in patients with a high score (≥5). The risk score had good discrimination (c-statistic, 0.73) and showed excellent calibration (P = .88).

Conclusions

On-admission prevalence of previously unknown MRSA carriers was high. Applying the risk score to newly admitted patients with an intermediate or high probability of MRSA carriage could allow a more effective MRSA control strategy.     

Estandarización de la técnica Dot-ELISA para la detección de anticuerpos anti-Trypanosoma cruzi y su comparación con ELISA y Western blot

Introduction

Chagas disease is considered endemic of Latin America. Because of migration of people from this region to non-endemic areas, such as the United States, Canada and Europe, it has become a major health problem. There are parasitology and serology tests for its diagnosis, but only the latter are useful during the chronic phase. Most of these tests require expensive equipment, which make them also inaccessible for laboratories in endemic areas. In the present work we standardize Dot-ELISA as a diagnostic test for Trypanosoma cruzi infection, since it is an easy, inexpensive and an accessible test.

Methods

A total of 360 samples were tested: 96 sera from Chagas patients and 153 from healthy people; 40 blood samples spots collected and eluted from filter paper were also tested, as well as 71 serum samples of patients with non-related infections. Sensitivity, specificity and kappa index of Dot-ELISA test were calculated, in order to determine a correlation value of this technique compared to ELISA and Western blot that are already being used for diagnosis.

Results

Dot-ELISA obtained 97% sensitivity and 89% specificity, since it showed cross-reaction mainly with Leishmania spp., and a kappa index of 0,79.

Conclusions

Dot-ELISA results correlate well with other tests that are already being used for diagnosis of Chagas disease. As it is easy and inexpensive, it may be useful as an additional diagnostic test or for field studies.     

La infección neonatal tardía por Streptococcus agalactiae en el área de Barcelona (1996-2010)

Objetive

To study the characteristics and evolution of group B Streptococcus (GBS) late-onset diseases, over a period of 15 years in 8 hospitals the Barcelona area and analyze the possible impact of prophylactic measures for the prevention of early-onset neonatal infections.

Methods

Retrospective review of all patients diagnosed with late-onset neonatal disease due to GBS from 1996 to 2010.

Results

A total of 143 patients were diagnosed. Of these, 51 were born in others hospitals. The overalll incidence was 0.42 per 1000 live births, varying between 0.14‰ in the year 2000 and 0.80‰ in 2009. A slight but sustained tendency of increased risk was observed over the years, 6.9% in the overall disease (with no statistical significance). Sepsis/bacteremia was detected in 63.6% of the newborns, meningitis in 32.8%, and arthritis/osteomyelitis in 3.5%. In cases with known obstetrics dates, 53% of mothers had been colonized by GBS during pregnancy, 53.8% received intrapartum antibiotic prophylaxis, and 41.2% had some obstetric risk factors, particularly premature birth in 35.9%. There was a 2.8% mortality rate in the neonates, and predominant serotypes were III and Ia.

Conclusions

The incidence of GBS late-onset disease has not decreased despite the control practices of early-onset disease, and possibility of this appearing must be taken into account.     

Efecto de la infección por Clostridium difficile sobre la estancia hospitalaria. Estudio de cohortes

Introduction

Clostridium difficile is responsible for a spectrum of diseases known as “Clostridium difficile infection” (CDI). It is currently the leading cause of nosocomial diarrhea in developed countries. This infection has been associated with both increased hospital stay and mortality, and to a greater likelihood of readmission. In our country these undesirable effects have not yet been characterized. Our objective was to quantify the increase in hospital stay attributable to infection by C. difficile.

Methods

A retrospective cohort study matched by age, sex and admission date, was conducted in a tertiary care university hospital during an outbreak of nosocomial transmission of CDI.

Results

The cohort study included 38 infected, and 76 non-infected patients. Patients who developed CDI showed a higher proportion of malnutrition at admission (OR = 10.3; 3.6 to 29.6), were exposed to a wider range of antibiotics (mean difference = 1.5; 0.7-2.2), had a higher mortality (31.6% vs. 6.6% of controls, P < .001), and a longer hospital stay (median 31.5 days versus 5.5 days for controls, P < .001). After adjustment, infection by C. difficile was associated with an increase in hospital stay of 4 days (P < .001).

Conclusions

C. difficile infection has important consequences on the length of hospital stay, and therefore on health costs.     

Staphylococcus aureus bacteremia in patients with prosthetic devices: costs and outcomes

Purpose

Although Staphylococcus aureus is a leading cause of nosocomial infection, little is known about the impact of S. aureus bacteremia on patients with prosthetic devices. This investigation sought to define the clinical outcome, health care resource use, and infection-associated costs of S. aureus bacteremia in patients with prostheses.

Subjects and methods

All hospitalized patients with a prosthetic device and S. aureus bacteremia during the 96-month study period were identified prospectively. Clinical data were collected at the time of hospitalization. Data regarding infection-related resource utilization and infection-related costs within 12 weeks of the initial bacteremia were also recorded.

Results

298 patients with ≥1 prosthesis and S. aureus bacteremia were identified (cardiovascular device—122 patients, orthopedic device—73 patients, long-term catheter—71 patients, and other devices—32 patients). Overall, 58% of patients underwent surgery as a consequence of the infection. Infection-related complications occurred in 41% and the overall 12-week mortality was 27%. The mean infection-related cost was $67 439 for patients with hospital-acquired S. aureus bacteremia and $37 868 for community-acquired S. aureus bacteremia (cost difference $29 571; 95% confidence interval, $14 370-$49 826). Rates of device infection, complications, 12-week mortality, and mean cost varied by prosthesis type.

Conclusion

S. aureus bacteremia in patients with prosthetic devices is associated with frequent complications, substantial cost, and significant health care resource utilization.     

The risk of infection after nasal colonization with Staphylococcus aureus

Purpose

Nasal, axillary, or inguinal colonization with Staphylococcus aureus generally precedes invasive infection. Some studies have found that colonization with methicillin-resistant S. aureus (MRSA) poses a greater risk of clinical infection than colonization with methicillin-susceptible S. aureus (MSSA). However, the magnitude of risk is unclear.

Methods

We undertook a systematic review to provide an overall estimate of the risk of infection following colonization with MRSA compared with colonization by MSSA. Ten observational studies, with a total of 1170 patients, were identified that provided data on both MSSA and MRSA colonization and infection. A random-effects model was used to obtain pooled estimates of the odds ratio and 95% confidence interval.

Results

Overall, colonization by MRSA was associated with a 4-fold increase in the risk of infection (odds ratio 4.08, 95% confidence interval, 2.10-7.44). Studies differed in the choice of patient population, severity of illness, and frequency of sampling to detect colonization.

Conclusion

Further research is needed to identify effective methods for sustained eradication of MRSA carriage to reduce the high risk of subsequent infection.     

Aplicación del análisis de los polimorfismos de los tamaños de los fragmentos de restricción del gen flaA amplificado por reacción en cadena de la polimerasa y resistotipo para identificar potenciales brotes de campilobacteriosis no diagnosticados en España

Introduction

Outbreaks of campylobacteriosis are infrequent and usually involve a low number of patients, although it is estimated that many more remain undiagnosed. The most successful techniques for outbreak investigation in Campylobacter spp. (PFGE, MLST) have the drawback of being laborious and not available in many laboratories.

Methods

During the year 2008, 352 isolates of C. jejuni and C. coli from 16 hospitals were received in our laboratory. All strains were genotyped by RFLP-PCR-flaA (flaA type) and phenotyped with their resistotype. It was established that the strains of the same species from the same hospital, isolated over a period of up to 11 days, with MIC values of ± 1 dilution with the same flaA type could belong to an outbreak. Strains that met these criteria would be later subtyped by KpnI-PFGE and MLST.

Results

A total of 23 out of 352 isolates, distributed in 10 groups, met the criteria for being associated with putative undiagnosed outbreaks. The similarity of the PFGE-profiles in 8 groups was greater than 95% among the isolates from each group. In 7 of the groups, the sequence types (MLST) were coincident.

Conclusions

The use of 2 easy markers (resistotype and RFLP-PCR-flaA) may detect isolates probably belonging to an undiagnosed outbreak of campylobacteriosis. Accurate diagnosis requires other molecular markers and epidemiological data of each isolate. The study suggests that, as in other countries, the number of outbreaks of campylobacteriosis in Spain is probably underestimated.     

Methicillin-resistant Staphylococcus aureus colonization among medical residents

BACKGROUND:

Medical residents may be at risk of becoming colonized by methicillin-resistant Staphylococcus aureus (MRSA) during their training. The occupational risk of this specific population is unknown. Furthermore, there are no data regarding MRSA colonization among health care professionals in Quebec.

OBJECTIVE:

To determine the MRSA colonization rate in Laval University (Quebec City, Quebec) medical residents and compare it with the MRSA colonization rate of a control group.

METHODS:

A controlled cross-sectional study of MRSA prevalence among medical residents of Laval University was performed. The control group consisted of Laval University undergraduate medical students without previous clinical rotations in their curriculum. After informed consent was obtained, participants were screened for MRSA with a nasal swab in both anterior nares. They also completed a questionnaire regarding relevant risk factors and demographic data.

RESULTS:

A total of 250 residents of all residency levels from medical and surgical specialties and 247 controls were recruited between February and April 2010. One case of MRSA colonization was detected among the residents and none in the control group (prevalence of 0.4% versus 0.0%; P=1.00).

DISCUSSION:

MRSA nasal carriage was very low among Laval University residents. This may reflect the decreasing rate of health care-associated MRSA in Quebec City. Young age and good health may also explain this low risk. The strict infection control policies for MRSA patients (including cohorting, use of gloves, gown and patient-dedicated equipment) may also contribute to prevent MRSA transmission.

CONCLUSIONS:

Medical residents in Quebec City appeared to be at very low risk of contracting MRSA through professional activities.     

Neisseria gonorrhoeae: resistencias antimicrobianas y estudio de la dinámica poblacional. Situación en 2011 en Barcelona

Background

Due to the high rates of antimicrobial resistance to certain antibiotics, together with the emergence of Neisseria gonorrhoeae (NG) with reduced susceptibility and resistance to third-generation cephalosporins, gonococcal infection is becoming a public health problem. The objectives of the study were: To keep track of the antimicrobial susceptibility of NG strains obtained from January to August 2011. To study the population dynamics.

Methods

The antimicrobial susceptibility was studied by disk-diffusion and E-test. The genotyping was performed by NG-MAST method.

Results

Of a total of 100 strains studied, 59% showed intermediate sensitivity to penicillin and 9% were resistant. According to EUCAST, we detected 3 gonococci with reduced susceptibility to ceftriaxone, 10 to cefixime and one with high-level resistance to both antibiotics (MIC 1.5 μg/ml). MIC₅₀ and MIC₉₀ to cefixime were 0.016 and 0.125 μg/ml, respectively, whereas to ceftriaxone they were < 0.016 and 0.064 μg/ml, respectively. Almost all (99%) of the strains were resistant to doxycycline, 53% to ciprofloxacin, 3% to azithromycin, and 1% to spectinomycin. The most prevalent ST was ST1407, predominantly associated to resistance or reduced sensitivity to cephalosporins or macrolides.

Conclusions

NG has developed significant rates of resistance to various antibiotics. One strain has been detected with high level resistance to third generation cephalosporins, and several strains with reduced susceptibility. An increase in MIC₅₀ and MIC₉₀ to these antibiotics has also been observed. NG population structure remains stable and common to the rest of Europe, although two new ST (ST7226 and ST7227) have been identified that could be selected and acquire high levels of resistance to cephalosporins.     

Back to the Future: Penicillin-Susceptible Staphylococcus aureus

Background

Widespread penicillin usage rapidly resulted in the emergence of penicillin resistance in Staphylococcus aureus. However, new data suggest that penicillin susceptibility may be in a period of renaissance. The objective of our study was to quantify penicillin resistance in methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia.

Methods

We retrospectively reviewed all adult MSSA bacteremia from April 2010 to April 2015 at the McGill University Health Centre (Montreal, QC, Canada). Susceptibility to penicillin, erythromycin, clindamycin, and trimethoprim-sulfamethoxazole (TMP-SMX) was determined in accordance with the Clinical & Laboratory Standards Institute guidelines.

Results

There were 324 unique episodes of MSSA bacteremia. Ninety (28%) isolates were susceptible to penicillin, 229 (71%) to erythromycin, 239 (74%) to clindamycin, and 317 (98%) to TMP-SMX. Isolates that were penicillin resistant were more likely to also be resistant to other antibiotics, but a statistically significant association was apparent only for erythromycin resistance (76/234, 32.2% vs 19/90, 21.1%, P = .04). The median age of patients was 67.5 years (interquartile range 52-78) and overall in-hospital 30-day mortality was 16.3% (53 deaths). After adjustment for patient age, there was no association between penicillin resistance and either intensive care unit admission or death.

Conclusion

More than one-quarter of patients with MSSA bacteremia potentially could be treated with parenteral penicillin, which may offer pharmacokinetic advantages over other beta-lactam drugs and potentially improved outcomes.