Christine Lawrence

Fluoroquinolone Use Is a Risk Factor for Methicillin-Resistant Staphylococcus aureus Acquisition in Long-term Care Facilities: A Nested Case-Case-Control Study

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization is a well-established risk factor for subsequent infection and a key event in interindividual transmission. Some studies have showed an association between fluoroquinolones and MRSA colonization or infection. The present study was performed to identify specific risk factors for MRSA acquisition in long-term care facilities (LTCFs). METHODS A prospective cohort of patients naive for S. aureus colonization was established and followed (January 2008 through October 2010) in 4 French LTCFs. Nasal colonization status and potential risk factors were assessed weekly for 13 weeks after inclusion. Variables associated with S. aureus acquisition were identified in a nested-matched case-case-control study using conditional logistic regression models. Cases were patients who acquired MRSA (or methicillin-sensitive S. aureus [MSSA]). Patients whose nasal swab samples were always negative served as controls. Matching criteria were center, date of first nasal swab sample, and exposure time. RESULTS Among 451 included patients, 76 MRSA cases were matched to 207 controls and 112 MSSA cases to 208 controls. Multivariable analysis retained fluoroquinolones (odds ratio, 2.17; 95% confidence interval, 1.01-4.67), male sex (2.09; 1.10-3.98), and more intensive care at admission (3.24; 1.74-6.04) as significantly associated with MRSA acquisition, and body-washing assistance (2.85; 1.27-6.42) and use of a urination device (1.79; 1.01-3.18) as significantly associated with MSSA acquisition. CONCLUSIONS Our results suggest that fluoroquinolones are a risk factor for MRSA acquisition. Control measures to limit MRSA spread in LTCFs should also be based on optimization of fluoroquinolone use.

Ceftazidime-Avibactam and Aztreonam an interesting strategy to Overcome β-Lactam Resistance Conferred by Metallo-β-Lactamases in Enterobacteriaceae and Pseudomonas aeruginosa

We have read with great interest the report by Marshall et al. regarding the efficacy of the combination of ceftazidime-avibactam (CAZ-AVI) and aztreonam (ATM) against metallo-β-lactamase-producing Enterobacteriaceae ([1][1]). These results confirm our experience with two patients treated with CAZ

Expected and unexpected adverse effects H1N1 vaccination for health care workers in a university hospital.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Expected and unexpected adverse effects H1N1 vaccination for health care workers in a university hospital. Aurelien Dinh, Christine Lawrence, Jérome Salomon, Alexis Descatha

Identifying more epidemic clones during a hospital outbreak of multidrug-resistant Acinetobacter baumannii.

Infections caused by multidrug-resistant bacteria are a major concern in hospitals. Current infection-control practices legitimately focus on hygiene and appropriate use of antibiotics. However, little is known about the intrinsic abilities of some bacterial strains to cause outbreaks. They can be measured at a population level by the pathogen’s transmission rate, i.e. the rate at which the pathogen is transmitted from colonized hosts to susceptible hosts, or its reproduction number, counting the number of secondary cases per infected/colonized host. We collected data covering a 20-month surveillance period for carriage of multidrug-resistant Acinetobacter baumannii (MDRAB) in a surgery ward. All isolates were subjected to molecular fingerprinting, and a cluster analysis of profiles was performed to identify clonal groups. We then applied stochastic transmission models to infer transmission rates of MDRAB and each MDRAB clone. Molecular fingerprinting indicated that 3 clonal complexes spread in the ward. A first model, not accounting for different clones, quantified the level of in-ward cross-transmission, with an estimated transmission rate of 0.03/day (95% credible interval [0.012–0.049]) and a single-admission reproduction number of 0.61 [0.30–1.02]. The second model, accounting for different clones, suggested an enhanced transmissibility of clone 3 (transmission rate 0.047/day [0.018–0.091], with a single-admission reproduction number of 0.81 [0.30–1.56]). Clones 1 and 2 had comparable transmission rates (respectively, 0.016 [0.001–0.045], 0.014 [0.001–0.045]). The method used is broadly applicable to other nosocomial pathogens, as long as surveillance data and genotyping information are available. Building on these results, more epidemic clones could be identified, and could lead to follow-up studies dissecting the functional basis for variation in transmissibility of MDRAB lineages.

Air Contamination around Patients Colonized with Multidrug-Resistant Organisms

Care-related infections are a major public health concern. Their transmission can be associated with environmental factors. This study looks at air contamination around 45 patients colonized with multidrug-resistant organisms (MDROs). We found that 30 hospital rooms (67%) were contaminated with MDRO species and 10 rooms (22%) were contaminated with at least 1 MDRO.

Fluoroquinolone Impact on Nasal Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus Colonization Durations in Neurologic Long-Term-Care Facilities

ABSTRACT Staphylococcus aureus nasal carriage is a risk factor for subsequent infection. Estimates of colonization duration vary widely among studies, and factors influencing the time to loss of colonization, especially the impact of antibiotics, remain unclear. We conducted a prospective study on patients naive for S. aureus colonization in 4 French long-term-care facilities. Data on nasal colonization status and potential factors for loss of colonization were collected weekly. We estimated methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) colonization durations using the Kaplan-Meier method and investigated factors for loss of colonization using shared-frailty Cox proportional hazards models. A total of 285 S. aureus colonization episodes were identified in 149 patients. The median time to loss of MRSA or MSSA colonization was 3 weeks (95% confidence interval, 2 to 8 weeks) or 2 weeks (95% confidence interval, 2 to 3 weeks), respectively. In multivariable analyses, the methicillin resistance phenotype was not associated with S. aureus colonization duration (P = 0.21); the use of fluoroquinolones (hazard ratio, 3.37; 95% confidence interval, 1.31 to 8.71) and having a wound positive for a nonnasal strain (hazard ratio, 2.17; 95% confidence interval, 1.15 to 4.07) were associated with earlier loss of MSSA colonization, while no factor was associated with loss of MRSA colonization. These results suggest that the methicillin resistance phenotype does not influence the S. aureus colonization duration and that fluoroquinolones are associated with loss of MSSA colonization but not with loss of MRSA colonization.

Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli versus Klebsiella pneumoniae: Does type of germ really matter?

To the Editor—We read with great interest the recent article by Scheuerman et al showing that extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) and Klebsiella pneumoniae (ESBL-KP) bloodstream infections (BSIs) differ significantly in terms of mortality (33.7% vs 17.4%; P= .016). Because their study concerns a highly relevant and popular topic, some points should be discussed. First, ESBL-KP–infected patients were more often hospitalized in ICU than those infected by ESBL-EC (P< .001), partly due to a septic shock, which may explain such a high rate of mortality (33.7%) for a bloodstream infection (BSI). Indeed, the observed mortality rate for ESBL-KP was similar to the average mortality for those with gram-negative BSIs in the ICU (35%) according to the prospective EUROBACT International cohort study. Also, ICU-acquired BSIs are associated with a 40% increase in the risk of 30-day mortality. Therefore, it is hard to believe that such a difference could be accounted for in any statistical adjustment, and thus, it constitutes a selection bias. Second, the main source of BSI was urinary tract in the ESBLEC arm (P= .005), while it is acknowledged that the severity of urinary tract infection is not related to the presence of bacteremia. Such data underly the hypothesis that ESBL-KP infections might have been more severe than those due to ESBL-EC. For instance, multidrug-resistant BSIs complicating respiratory tract infections have been associated with an increased mortality (odds ratio [OR], 3.26; 95% confidence interval [CI], 1.29–8.22). Third, no information is provided about the respective antimicrobial regimens between ESBL-EC and ESBL-KP patients. However, it is currently argued that carbapenem alternatives are associated with a higher mortality rate than carbapanems for the treatment of ESBL BSI. In fact, the MERINO trial by Harris et al was recently suspended due to an increase in mortality in the arm receiving piperacillin-tazobactam (12.3%) versus meropenem (3.7%). Such data should have been discussed. Likewise, no information is provided on treatment duration or dose, which may have varied between the 2 groups in the present study. Both factors play a role in the outcome of treatment, especially when used against multidrug-resistant organisms. Interestingly, we previously showed that BSI severity or mortality among spinal cord injury patients over 15 years was not related to the multidrug-resistant characteristics of the microorganism. Although our sample size was small (n< 30), a closer look at the outcome between ESBL-EC (n= 26) and ESBL-KP (n= 13) did not reveal any statistical difference in terms of mortality rate (7.7% in each arm). Moreover, the mortality rates were similar for other ESBL microorganisms (Enterobacter spp, Morganella spp, and Proteus spp (n=21)), ~ 9.5% (P= .99, data not shown). In fact, we believe that the findings of Scheuerman et al, which showed no impact of CTX-M isolates in comparison to other ESBL genotypes, might support the idea that the type of germ does not play a major role. Indeed, mortality seems more related to patient comorbidities and severity of infection, as shown in Table 2 of the article, with significant discrepancies between the 2 groups in terms of length of stay to bacteremia (P= .017), source of infection (P= .005), ICU ward admission (P< .001) and underlying cardiovascular disease (P< .001). Moreover, in a rabbit model of sepsis induced by a multidrug-resistant Klebsiella pneumoniae, Zhou et al showed that mortality was higher for the rabbits infected by susceptible than those infected with multidrug-resistant strains. Overall, the impact of ESBL-KP isolates on mortality rate might have been overestimated, in the light of the severity of the patient condition.