Spread of clonal linezolid-resistant Staphylococcus epidermidis in an intensive care unit associated with linezolid exposure.

The aim of the study was to determine factors associated with spread of linezolid (LNZ)-resistant Staphylococcus epidermidis isolates in a surgical intensive care unit (ICU). A case-control study was conducted in one French adult surgical ICU. From January 2012 to December 2016, patients with at least a single positive LNZ-resistant S. epidermidis blood culture were matched to control with LNZ-susceptible S. epidermidis blood culture in a 1:4 manner. Cases were compared to controls regarding baseline clinical characteristics and LNZ exposure before positive blood culture. Bacterial isolates were genotyped by using pulsed-field gel electrophoresis (PFGE) and MLST. We identified 13 LNZ-resistant S. epidermidis isolates, 1 in 2012, 3 in 2014, 6 in 2015, and 3 in 2016. LNZ use increased steadily from 8 DDDs/100 patient days in 2010 to 19 in 2013 and further decrease by more of 50% in 2015 and 2016. The only independent risk factors associated to LNZ-resistant S. epidermidis isolation were length of stay in ICU before infection (OR 1.45; 95% CI 1.07-1.98), prior exposure to LNZ (OR 109; 95% CI 3.9-3034), and Charlson comorbidities score (OR 3.19; 95% CI 1.11-9.14). PFGE typing showed that all LNZ-resistant isolates were clonal belonging to ST2 and that LNZ-susceptible isolates were highly diverse. We report herein that previous exposure to LNZ substantially increased the risk of occurrence of LNZ resistance in S. epidermidis even in the case of clonal spread of LNZ-resistant isolates. These findings highlight the need for reducing the use of LNZ to preserve its efficacy in the future.

Whole genome sequencing revealed new molecular characteristics in multidrug resistant staphylococci recovered from high frequency touched surfaces in London.

The rise of antibiotic resistance (AMR) is one of the most important public health threats worldwide.Today, increasing attention is being paid to multidrug resistant staphylococci isolated from healthcare and non-healthcare environments as the treatment of these bacteria has become increasingly difficult. In this study, we compared staphylococci isolates recovered from high frequency touched surfaces from public areas in the community and hospitals in East and West London. 281 out of 600 (46.83%) staphylococci isolates recovered were multidrug resistant, of which 49 (8.17%) were mecA positive. There was significantly higher proportion of multidrug resistant staphylococci (P = 0.0002) in East London (56.7%) compared to West London (49.96%). The most common species identified as multidrug resistant were S. epidermidis, S. haemolyticus and S. hominis, whereas penicillin, fusidic acid and erythromycin were the most frequent antibiotics the isolates were resistant to. Whole genome sequenced of mecA positive isolates revealed that S. sciuri isolates carried the mecA1 gene, which has only 84.43% homology with mecA. In addition, other frequently identified resistance genes included blaZ, qacA/B and dfrC. We have also identified a diverse range of SCCmec types, many of which were untypable due to carrying a novel combination of ccr genes or multiple ccr complexes.

Increase of zinc resistance in German human derived livestock-associated MRSA between 2000 and 2014.

PROBLEM ADDRESSED: Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA), particularly of the clonal complex (CC) 398, emerged as zoonotic pathogens predominantly among humans with direct or indirect livestock contact, but also in healthcare settings. The factors contributing to the success of LA-MRSA are only poorly understood. OBJECTIVE: During the past years, the use of heavy metal compounds as feed-supplements was found to influence the co-selection of LA-MRSA in pig herds. This study aimed to determine the prevalence of zinc resistance among MRSA CC398 isolated from patients of a German university hospital located in a pig farming-dense area. METHODS AND APPROACH: In comparison to concurrent healthcare-associated MRSA (HA-MRSA), LA-MRSA CC398 comprising isolates from their first appearance in 2000 to recent isolates from 2014 were included. RESULTS: Among MRSA CC398, the overall resistance rate towards zinc chloride was 57% compared to only 3% among concurrently isolated HA-MRSA. Zinc resistance correlated with the presence of the czrC gene in 100% of the MRSA CC398 and in 67% of the HA-MRSA. CONCLUSIONS: The zinc resistance rate in MRSA CC398 significantly increased from 2009 to 2014 with a maximum in 2014. Alarmingly, zinc resistance has become a frequent phenotype of human LA-MRSA in Germany potentially facilitating co-selection of antibiotic resistance genes.

Preventing transmission of MRSA: a qualitative study of health care workers' attitudes and suggestions.

BACKGROUND: Health care workers' (HCWs) perceptions and attitudes affect implementation of precautions to prevent transmission of drug-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). Identification of challenges and barriers to recommended practices is a critical component of promoting a safe clinical environment of care. METHODS: Semistructured interviews addressed how MRSA affects HCWs, prevention of transmission, and challenges and barriers HCWs experience when entering a MRSA isolation room and performing appropriate hand hygiene. RESULTS: The purposive sample of 26 acute care HCWs (16 registered nurses; 1 physician; 6 allied health professionals; and 3 support staff) self-selected from 276 responding to a questionnaire on MRSA. Analysis identified 18 themes across seven categories. Most participants reported feeling responsible for preventing transmission, and having the knowledge and desire to do so. However, many also reported challenges to following consistent hand hygiene and use of contact precautions. Barriers included patient care demands, equipment and environmental issues such as availability of sinks, time pressures, the practices of other HCWs, and the need for additional signs indicating which patients require contact precautions. CONCLUSIONS: The HCWs reported a need for improved clarity of isolation protocols throughout patients' hospital journey, additional rooms and staff for isolation patients, improved education and communication (including timely and appropriate signage), and an emphasis on involving all HCWs in reducing contamination.

Hospital networks and the dispersal of hospital-acquired pathogens by patient transfer.

Hospital-acquired infections (HAI) are often seen as preventable incidents that result from unsafe practices or poor hospital hygiene. This however ignores the fact that transmissibility is not only a property of the causative organisms but also of the hosts who can translocate bacteria when moving between hospitals. In an epidemiological sense, hospitals become connected through the patients they share. We here postulate that the degree of hospital connectedness crucially influences the rates of infections caused by hospital-acquired bacteria. To test this hypothesis, we mapped the movement of patients based on the UK-NHS Hospital Episode Statistics and observed that the proportion of patients admitted to a hospital after a recent episode in another hospital correlates with the hospital-specific incidence rate of MRSA bacteraemia as recorded by mandatory reporting. We observed a positive correlation between hospital connectedness and MRSA bacteraemia incidence rate that is significant for all financial years since 2001 except for 2008-09. All years combined, this correlation is positive and significantly different from zero (partial correlation coefficient r = 0.33 (0.28 to 0.38)). When comparing the referral pattern for English hospitals with referral patterns observed in the Netherlands, we predict that English hospitals more likely see a swifter and more sustained spread of HAIs. Our results indicate that hospitals cannot be viewed as individual units but rather should be viewed as connected elements of larger modular networks. Our findings stress the importance of cooperative effects that will have a bearing on the planning of health care systems, patient management and hospital infection control.

[Is it necessary to know which workers are carriers of MRSA in contact with cancer patients?]. / ¿Es necesario conocer qué trabajadores son portadores de SARM en contacto con enfermos oncológicos?

Our objective was to determine the prevalence of methicillin-resistant Staphylococcus aureus in workers who had direct contact with oncologic patients infected with MRSA and admitted to the intensive care unit of the Valencian Institute of Oncology. A study of prevalence of MRSA colonization of 62 workers was performed. Samples were taken from nose and pharynx in each of the workers. After 24 hours of incubation in Amies transport medium Viscose (Eurotubo®), 124 samples were seeded (N = 124) in chocolate agar agar, MRSA II and BHI broth (Brain Heart Infusion). Those colonies that were identified by Gram stain gram-positive cocci in clusters available, catalase positive and coagulase positive were processed for study of sensitivity by Kirby-Bauer method and screening test for methicillin (10µg of Oxoid®) on Mueller-Hinton (Becton-Dickinson®, BD), supplemented with NaCl (2%). Those confirmed MRSA isolates, he returned to perform sensitivity study by microdilution (MicroScan®, Siemens) to determine the MIC (mg/L). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) was 1.61% (1) and 12.90% (8) for methicillin-sensitive Staphylococcus aureus (MSSA), from nostrils. The measures implemented were: nasal application of mupirocin to the worker colonized control isolation measures in infected patients and indoctrination of the personnel involved.

Dynamic of nasal colonization by methicillin-resistant Staphylococcus aureus ST398 and ST1 after mupirocin treatment in a family in close contact with pigs.

Nasal colonization by methicillin-resistant Staphylococcus aureus (MRSA) was evaluated after a mupirocin treatment in a family previously colonized by MRSA sequence type ST398 and ST1, who lived close to a pig farm. Eight nasal samples were swabbed from each of the four family members on different moments after mupirocin treatment. The efficacy of treatment was low in those family members who worked in the farm, and higher in the remaining two family members with sporadic contact with pigs. In addition, nasal and skin swabs from randomly selected pigs of the farm were taken. MRSA were detected in 33% of pigs tested. All MRSA isolates obtained were characterized by Staphylococcal-Cassette-Chromosome mec (SCCmec) determination, Multilocus-Sequence-Typing (MLST), spa- and agr-typing, Pulsed-field-gel-electrophoresis (PFGE), antimicrobial susceptibility, detection of antimicrobial resistance genes, and toxin gene profiling. Spa-types t011, t1255 and t1197 were detected in humans and animals, with indistinguishable PFGE patterns, suggesting animal to human MRSA transmission. Each spa-type was ascribed to a specific pulsotype. Spa-types t127 and t108 were only detected in MRSA isolates obtained from humans, and t012 only in those from animals. MRSA ST1-t127 isolates and some ST398-t011 and ST398-t1197 isolates presented a multiantimicrobial-resistance phenotype. None of them harbored lukF/lukS, tst, eta and etb virulence genes. This study showed that the efficacy of nasal MRSA decolonization in healthy people with very close contact with pigs is especially low.

Agents for the decolonization of methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) bacteria are a common cause of hospital- and community-acquired infections. Persons may have asymptomatic colonization with MRSA in the nares, axillae, perineum, or groin. Since MRSA colonization often precedes infection, and infection is associated with significant morbidity and mortality, there is great interest in preventing the transmission of MRSA and decolonizing persons who harbor these bacteria. We provide an evidence-based review of MRSA decolonization agents. Our search strategy included the databases of the Cochrane Central Register of Controlled Trials, MEDLINE (1962-May 2008), and EMBASE (1980-May 2008). To identify unpublished trials, abstract books from appropriate major scientific meetings were hand searched, manufacturers were contacted, and pharmacology references were researched for available commercial products, formulations, adverse events, and dosing. The most extensive research in MRSA decolonization has been conducted with mupirocin, which is applied to the anterior nares 2-3 times/day for 5 days. Increased use is correlated to resistance development; therefore, routine decolonization is not prudent unless MRSA colonization is confirmed in the nares or other site. Retapamulin is under investigation for use in nares decolonization. If total body decolonization is necessary, bathing or showering with an antiseptic agent such as chlorhexidine gluconate is recommended in combination with mupirocin applied to the nares to improve the likelihood of eradication. Oral antibiotics have been evaluated for use in decolonization of the skin and nares but should be considered only in conjunction with topical agents and when all other decolonization attempts and environmental controls have been exhausted. Homeopathic and investigational agents may also be effective. Although mupirocin is the standard of care for decolonization of MRSA, several agents demonstrate efficacy and many merit further investigation.

Outbreak of invasive methicillin-resistant Staphylococcus aureus infection associated with acupuncture and joint injection.

OBJECTIVE: To describe an outbreak of invasive methicillin-resistant Staphylococcus aureus (MRSA) infection after percutaneous needle procedures (acupuncture and joint injection) performed by a single medical practitioner. SETTING: A medical practitioner's office and 4 hospitals in Perth, Western Australia. PATIENTS: Eight individuals who developed invasive MRSA infection after acupuncture or joint injection performed by the medical practitioner. METHODS: We performed a prospective and retrospective outbreak investigation, including MRSA colonization surveillance, environmental sampling for MRSA, and detailed molecular typing of MRSA isolates. We performed an infection control audit of the medical practitioner's premises and practices and administered MRSA decolonization therapy to the medical practitioner. RESULTS: Eight cases of invasive MRSA infection were identified. Seven cases occurred as a cluster in May 2004; another case (identified retrospectively) occurred approximately 15 months earlier in February 2003. The primary sites of infection were the neck, shoulder, lower back, and hip: 5 patients had septic arthritis and bursitis, and 3 had pyomyositis; 3 patients had bacteremia, including 1 patient with possible endocarditis. The medical practitioner was found to be colonized with the same MRSA clone [ST22-MRSA-IV (EMRSA-15)] at 2 time points: shortly after the first case of infection in March 2003 and again in May 2004. After the medical practitioner's premises and practices were audited and he himself received MRSA decolonization therapy, no further cases were identified. CONCLUSIONS: This outbreak most likely resulted from a breakdown in sterile technique during percutaneous needle procedures, resulting in the transmission of MRSA from the medical practitioner to the patients. This report demonstrates the importance of surveillance and molecular typing in the identification and control of outbreaks of MRSA infection.

[Clindamycin is unsuitable for the empirical treatment of infections due to pig-related methicillin-resistant Staphylococcus aureus (MRSA)]. / Clindamycine niet geschikt voor empirische behandeling van infecties veroorzaakt door meticillineresistente Staphylococcus aureus (MRSA) afkomstig van varkens.

OBJECTIVE: To determine the antibiotic sensitivity of methicillin-resistant Staphylococcus aureus (MRSA) isolated from persons in contact with pigs. DESIGN: Retrospective. METHOD: The pig-related MRSA collection, built up between January 1st 2003 and November 30th 2006 in the Regional Laboratory for Medical Microbiology and Infection Prevention (RLMMI) of the Jeroen Bosch Hospital, Den Bosch, The Netherlands, was tested for sensitivity to a large number ofantibiotics. RESULTS: A total of 65 isolates were obtained from 53 patients. All (100%) of the pig-related MRSA isolates were sensitive to vancomycin, teicoplanin, nitrofurantoin, rifampicin, linezolid, and quinupristin-dalfopristin. Variable sensitivity was found for erythromycin (40%), clindamycin (48%), cotrimoxazole (48%), aminoglycosides (92%), tetracycline (6%), and quinolones (94%). CONCLUSION: In view of the sensitivities found, clindamycin does not seem suitable for the empirical therapy ofpig-related MRSA-infections. In case of severe infection, therapy should be started either with an intravenous glycopeptide or with oral ciprofloxacin, possibly combined with rifampicin or linezolid.

Almond oil implicated in a Staphylococcus capitis outbreak in a neonatal intensive care unit.

OBJECTIVE: To develop an effective outbreak-control strategy by identifying the source and modes of transmission of Staphylococcus capitis in a 60-bed neonatal intensive care unit (NICU). STUDY DESIGN: We conducted a study among neonates hospitalized during the outbreak (June 2000 through November 2003). All cases of S. capitis colonization or infection detected by clinical samples during the outbreak were included. The molecular analysis of the isolated was assessed by pulsed-field electrophoresis. We reported the description of the outbreak and the measures taken during this investigation. RESULT: Thirty-three patients were colonized or infected by S. capitis. Mean gestational age was 28.5+/-4.4 weeks of gestation, mean birth weight was 1068+/-637.3 g and the mean length of hospital stay was 77.9+/-35.9 days. We observed that positive S. capitis cultures were over-represented in six beds of the NICU. Because S. capitis is known to thrive in lipid media, we cultured samples from the almond oil bottles assigned to these beds. S. capitis strain recovered from one of the almond oil sample was genetically identical to the strain recovered from the cases. CONCLUSION: Almond oil is an unusual reservoir infection. Control policy allowed prompt institution of measures that were successful in ending the outbreak.

Colonização microbiana precoce de pacientes identificados por triagem neonatal para fibrose cística, com ênfase em Staphylococcus aureus / Early microbial colonization of cystic fibrosis patients identified by neonatal screening, with emphasis on Staphylococcus aureus

OBJETIVOS: Avaliar prospectivamente a colonização bacteriana de pacientes com fibrose cística identificados por triagem neonatal. Avaliar a suscetibilidade a antimicrobianos e caracterizar molecularmente as cepas de Staphylococcus aureus isoladas da orofaringe dos pacientes no período do estudo. MÉTODOS: Foram estudados 25 pacientes com fibrose cística, identificados por tripsina imunorreativa e com diagnóstico confirmado por duas ou mais provas de suor, atendidos regularmente no ambulatório de fibrose cística do Hospital de Clínicas da Universidade Federal do Paraná. Foram coletadas amostras de orofaringe com swab e cultivadas por métodos rotineiros; as colônias bacterianas foram identificadas fenotipicamente e testadas quanto à suscetibilidade a antimicrobianos. Os isolados de S. aureus foram submetidos a tipagem molecular por eletroforese em campo pulsado. RESULTADOS: De um total de 234 amostras de orofaringe, S. aureus foi isolado em maior número (76 por cento dos pacientes, 42 por cento das amostras), seguido de Pseudomonas aeruginosa (36 por cento dos pacientes, 16 por cento das amostras) e Haemophilus spp. (76 por cento dos pacientes; 19 por cento das amostras). Dos 19 pacientes colonizados com S. aureus, foram obtidos 73 isolados, 18 oxacilina-resistentes (24,6 por cento), isolados de dois pacientes, com perfis eletroforéticos idênticos ao do clone brasileiro. Os demais isolados oxacilina-sensíveis distribuíram-se entre 18 perfis eletroforéticos distintos. CONCLUSÃO: Observou-se uma maior prevalência de S. aureus, com isolamento mais precoce em relação aos outros patógenos pesquisados. Os isolados multissensíveis distribuíram-se em clones distintos, caracterizando a não transmissibilidade entre as cepas comunitárias. Os S. aureus resistentes a oxacilina isolados apresentaram perfis eletroforéticos idênticos, provavelmente adquiridos no ambiente hospitalar. P. aeruginosa foi pouco freqüente na população estudada.

OBJECTIVES: To assess bacterial colonization prospectively in patients with cystic fibrosis identified by neonatal screening. To assess susceptibility to antimicrobials and to perform the molecular typing of Staphylococcus aureus strains isolated from the oropharynx of patients during the study. METHODS: Twenty-five cystic fibrosis patients receiving regular treatment at the Cystic Fibrosis Outpatient Clinic of Hospital de Clínicas of Universidade Federal do Paraná Brazil, were included in the study. All patients were identified by trypsin-like immunoreactivity and their diagnosis was confirmed by two or more sweat tests. Oropharyngeal swabs were collected and cultured according to routine methods; bacterial colonies were phenotypically identified and their susceptibility to antimicrobials was tested. S. aureus isolates were submitted to molecular typing using pulsed-field gel electrophoresis. RESULTS: Out of 234 oropharyngeal swabs, S. aureus was the most frequently isolated strain (76 percent of patients, 42 percent of swabs), followed by Pseudomonas aeruginosa (36 percent of patients, 16 percent of swabs) and Haemophilus spp. (76 percent of patients; 19 percent of swabs). Seventy-three isolates were obtained from 19 patients colonized with S. aureus, of which 18 were oxacillin-resistant (24.6 percent), isolated from two patients, with the same electrophoretic profiles as that of the Brazilian clone. The remaining oxacillin-sensitive isolates were distributed into 18 electrophoretic profiles. CONCLUSION: There was higher prevalence of S. aureus, with earlier isolation than other pathogens. Multi-sensitive isolates were distributed into different clones, characterizing non-transmissibility among community-acquired strains. The isolated oxacillin-resistant S. aureus showed identical electrophoretic profiles, probably acquired in hospital. P. aeruginosa was not so frequent in the studied population.

Early microbial colonization of cystic fibrosis patients identified by neonatal screening, with emphasis on Staphylococcus aureus.

OBJECTIVES: To assess bacterial colonization prospectively in patients with cystic fibrosis identified by neonatal screening. To assess susceptibility to antimicrobials and to perform the molecular typing of Staphylococcus aureus strains isolated from the oropharynx of patients during the study. METHODS: Twenty-five cystic fibrosis patients receiving regular treatment at the Cystic Fibrosis Outpatient Clinic of Hospital de Clínicas of Universidade Federal do Paraná, Brazil, were included in the study. All patients were identified by trypsin-like immunoreactivity and their diagnosis was confirmed by two or more sweat tests. Oropharyngeal swabs were collected and cultured according to routine methods; bacterial colonies were phenotypically identified and their susceptibility to antimicrobials was tested. S. aureus isolates were submitted to molecular typing using pulsed-field gel electrophoresis. RESULTS: Out of 234 oropharyngeal swabs, S. aureus was the most frequently isolated strain (76% of patients, 42% of swabs), followed by Pseudomonas aeruginosa (36% of patients, 16% of swabs) and Haemophilus spp. (76% of patients; 19% of swabs). Seventy-three isolates were obtained from 19 patients colonized with S. aureus, of which 18 were oxacillin-resistant (24.6%), isolated from two patients, with the same electrophoretic profiles as that of the Brazilian clone. The remaining oxacillin-sensitive isolates were distributed into 18 electrophoretic profiles. CONCLUSION: There was higher prevalence of S. aureus, with earlier isolation than other pathogens. Multi-sensitive isolates were distributed into different clones, characterizing non-transmissibility among community-acquired strains. The isolated oxacillin-resistant S. aureus showed identical electrophoretic profiles, probably acquired in hospital. P. aeruginosa was not so frequent in the studied population.

Sources of intramammary infections from Staphylococcus aureus in dairy heifers at first parturition.

The study objective was to identify probable sources and modes of transmission of 91 Staphylococcus aureus isolates obtained from the colostrum of 76 heifers at parturition. Sources cultured were milk (including colostrum), heifer body sites (teats, muzzle, rectum, vagina, and lacteal secretions), and environmental sites (bedding, insects, housing, water, feedstuffs, humans, nonbovine animals, air, and equipment). Staphylococcus aureus isolates were characterized by 63 phenotypic traits. A similarity coefficient was calculated by herd to identify the S. aureus that most closely resembled the S. aureus obtained from heifer colostrum. Staphylococcus aureus from a heifer's colostrum was compared with all preexisting S. aureus isolates from that heifer's herd. Isolates that were > or = 90% similar were considered to be identical. Because 30 (of the 91) S. aureus isolates from heifer colostrum were collected prior to environmental sampling, only 61 S. aureus isolates from heifer colostrum were available for comparison among all three sources. Possible sources of S. aureus from heifer colostrum at parturition were milk (70%, 43 of 61 isolates), heifer body sites (39%, 24 of 61), environmental sites (28%, 17 of 61), or no identified source (16%, 10 of 61). Three heifers with intramammary infection (IMI) from S. aureus at parturition had the same S. aureus on their teats prior to parturition. Milk was the only source identified for 41% (25 of 61) of isolates from heifer colostrum. Isolates from heifer body sites were the only source identified for 5% (3 of 61) of heifer colostrum isolates. Staphylococcus aureus from the environment was never the sole possible source for S. aureus from heifer colostrum. Data suggest that the major sources of S. aureus IMI in heifers at parturition are milk and heifer body sites. Contact among heifers may be an important mode of transmission of S. aureus leading to IMI in heifers at parturition.

Quinolone resistance in Pseudomonas aeruginosa and Staphylococcus aureus. Development during therapy and clinical significance.

This review focuses on published information on the experimental as well as clinical data on the emergence of quinolone resistant isolates. In the course of clinical use of fluoroquinolones, only a sporadic emergence of quinolone resistance has been noted. The resistant organisms emerged particularly in certain clinical settings where large numbers of organisms frequently causing chronic infections are present and/or in loci where quinolone concentrations may not be optimal. In terms of occurrence in individuals, quinolone resistance has emerged most frequently in hospitalized and nursing-home patients with identifiable risk factors. Epidemiological studies revealed that in nearly all the cases studied one or one predominating quinolone resistant clone was selected that was horizontally transmitted. Thus, the emergence of quinolone resistance is not due to an independent selection of resistant strains in a number of patients, but to the clonal spread of one strain once it has acquired quinolone resistance. Therefore, the rate of quinolone resistance is very likely to be lower than reported.