Typing of Methicillin Resistant Staphylococcus Aureus Using DNA Fingerprints by Pulsed-field Gel Electrophoresis

The Dissemination and Molecular Characterization of Clonal Complex 361 (CC361) Methicillin-Resistant Staphylococcus aureus (MRSA) in Kuwait Hospitals

Methicillin-resistant Staphylococcus aureus (MRSA) belonging to clonal complex 361 (CC361-MRSA) is rare among patients’ populations globally. However, CC361-MRSA has been isolated with an increasing trend among patients in Kuwait hospitals since 2010. This study investigated the molecular characteristics of CC361-MRSA isolated from patients in Kuwait hospitals in 2016–2018 to understand their genetic relatedness and virulence determinants. Of 5,223 MRSA isolates investigated by DNA microarray, 182 (3.4%) isolates obtained in 2016 (N = 55), 2017 (N = 56), and 2018 (N = 71) were identified as CC361-MRSA. The CC361-MRSA isolates were analyzed further using antibiogram, spa typing and multi locus sequence typing (MLST). Most of the isolates were resistant to fusidic acid (64.8%), kanamycin (43.4%), erythromycin (36.3%), and clindamycin (14.3%) encoded by fusC, aphA3, and erm(B)/erm(C) respectively. Nine isolates (4.9%) were resistant to linezolid mediated by cfr. The isolates belonged to 22 spa types with t3841 (N = 113), t315 (N = 16), t1309 (N = 14), and t3175 (N = 5) constituting 81.3% of the spa types, four genotypes (strain types), CC361-MRSA-[V/VT + fus] (N = 112), CC361-MRSA-IV, WA MRSA-29 (N = 36), CC361-MRSA-V, WA MRSA-70/110 (N = 33) and CC361-MRSA-[V + fus] variant (N = 1). MLST conducted on 69 representative isolates yielded two sequence types: ST361 (11/69) and ST672 (58/69). All CC361-MRSA isolates were positive for cap8, agr1, and the enterotoxin egc gene cluster (seg, sei, selm, seln, selo, and selu). The tst1 was detected in 19 isolates. The immune evasion cluster (IEC) genes type B (scn, chp, and sak) and type E (scn and sak) were detected in 20 and 152 isolates, respectively. The CC361-MRSA circulating in Kuwait hospitals consisted of two closely related sequence types, ST361 and ST672 with ST672-MRSA [V/VT + fus] as the dominant genotype. The dissemination of these newly emerged clones and the emergence of linezolid resistance limits therapeutic options, as well as present significant challenges for the control of MRSA infections in Kuwait hospitals.

Livestock-Associated Methicillin-Resistant Staphylococcus aureus From Animals and Animal Products in the UK

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is an emerging problem in many parts of the world. Although animal-adapted LA-MRSA has been known for many years, recent reports suggest a possible increasing trend in the zoonotic transmission of LA-MRSA in Europe. Since its emergence in the early 2000's, several investigations have indicated that persons in prolonged, repeated contact with affected livestock are at a higher risk of becoming colonized with LA-MRSA. LA-MRSA monitoring in livestock is voluntary under current EU legislation, and not all member states, including the UK, participate. UK LA-MRSA isolates have been detected through scanning surveillance, where samples are submitted from clinically diseased livestock for diagnostic investigation, and research studies. Surveys conducted on retail beef, pig and poultry meat on sale in the UK have also detected LA-MRSA. Taken together these results suggest that LA-MRSA is present in the UK, possibly at low prevalence level, as suggested by available evidence. In this review, we examine the data available from UK livestock and animal products, and make recommendations for future. We also review the findings from whole genome sequencing (WGS) of the possible lineage of some UK livestock isolates.

"Is our choice of empirical antibiotics appropriate for patients with methicillin resistant Staphylococcus aureus in breast abscess?"

BACKGROUND AND OBJECTIVES

Breast abscesses remain as one of the most common reasons for females to come for a surgical consult. This retrospective cohort study includes both lactating and non-lactating females with breast abscesses. Due to changing trends in bacteriology of organisms, we need to reconsider our empirical choices of antibiotics. In our study, the main causative organism in breast abscess was Staphylococcus aureus with predominant species being MRSA.

MATERIALS AND METHODS

This is an analytical review of all breast abscesses treated in a single center from 2012 to 2015. This study included bacterial cultures, antibiotic sensitivities and resistance pattern in breast abscesses.

RESULTS

268 patients were included in the study. 143 (53.4%) were Lactational abscesses and 125 (46.6%) were non-Lactational abscesses. 169 (63.0%) harbored S. aureus in which 86 (50.8%) were MRSA. MRSA was the predominant organism in the Lactational group while non-Lactational group had no growth or other organisms in culture in this study. Other growing organisms were Klebsiella pneumoniae, Bacteroides, Pseudomonas, Streptococcus species and Mycobacterium tuberculosis. On comparative analysis, MRSA showed statistically a significant difference with p<0.0001, when it comes to predominant growth in lactating mothers. First line prescribed empirical antibiotics received by the patient, which is amoxicillin clavulanate, is mostly resistant. It is recommended that the institutional antibiogram targeted treatment be offered to patients with breast abscess. We also recommend ciprofloxacin with clindamycin as initial empirical therapy.

CONCLUSION

MRSA was the most common organism seen in breast abscesses. Our first line treatment of antibiotics was resistant. Clindamycin and ciprofloxacin should be the preferred 1^st choice for treatment.

Methicillin-resistant Staphylococcus aureus tracking spread among health-care workers and hospitalized patients in critical wards at a university hospital, Tehran, Iran

Health-care workers may serve as a reservoir for dissemination of methicillin-resistant Staphylococcus aureus (MRSA) to patients in hospital settings. The present study aimed to screen MRSA in nasal swabs of health-care workers and clinical specimens from patients and investigate the possible relationship between these isolates at a university hospital in Tehran, Iran. Additionally, we aimed to identify potential risk factors for MRSA colonization in health-care workers. Staphylococcus aureus strains were isolated from health-care workers and inpatients who completed a questionnaire on risk factors. Cefoxitin disc diffusion test was also used for detection of MRSA. Moreover, all of the MRSA isolates were subjected to pulsed-field gel electrophoresis (PFGE). Colonization rate of MRSA among health-care workers was 22.5%. Furthermore, out of 24 S. aureus isolates obtained from patients, nine (37.5%) were MRSA. Regarding risk factors, the prevalence of nasal MRSA carriage among hospital personnel who used masks was significantly lower than in those without masks (p 0.007). Using PFGE, 10 clusters and 14 singletons were identified among the MRSA isolates. In this regard, most of the MRSA isolates recovered from health-care carriers and patients in intensive care wards, especially general intensive care units, were grouped in certain clusters, indicating intra-ward transmission of the mentioned isolates in these restricted areas. We concluded that screening and decolonization of carriers, contact precautions, prudent use of antibiotics and implementation of active surveillance are recommended strategies for the prevention and control of MRSA transmission in hospital settings.

Prevalence of methicillin-resistant Staphylococcus aureus colonisation among healthcare workers at a tertiary care hospital in southeastern China

OBJECTIVES

The aim of this study was to investigate the carriage rates of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) among healthcare workers (HCWs) at a tertiary-care hospital in southeastern China and to analyse the epidemiological relatedness of the S. aureus isolates.

METHODS

A total of 242 pharynx swabs were collected in March-April 2016 from 242 HCWs working in seven different wards and departments. Isolates were identified as S. aureus based on morphology, coagulase test and Vitek test. Antimicrobial susceptibility testing was performed by using the Kirby-Bauer disk diffusion method. The epidemiological relatedness of the S. aureus isolates was determined by pulsed-field gel electrophoresis (PFGE).

RESULTS

From the 242 HCWs, 70 (28.9%) S. aureus strains, including 10 (4.1%) MRSA strains, were identified during screening, with the highest MRSA rate detected in nurses (8/107; 7.5%). Carriage rates of S. aureus and MRSA among surgical HCWs were 30.0% (63/210) and 4.3% (9/210), respectively. Methicillin-susceptible S. aureus (MSSA) isolates were grouped by PFGE analysis into five similar groups (A-E), with most isolates belonging to groups D and E, accounting for 63.0% of isolates. Furthermore, two MRSA isolates from gastrointestinal surgery had identical PFGE patterns.

CONCLUSIONS

The prevalence of S. aureus colonisation among HCWs was high in this hospital, although the MRSA carriage rate in surgical wards was low. The identical PFGE pattern detected in two MRSA isolates from the same surgical department supports that effective control for possible cross-infection should be implemented.

Management of methicillin-resistant Staphylococcus aureus mediated ventilator-associated pneumonia

Prevention strategies and clinical management of methicillin- resistant Staphylococcus aureus (MRSA) infections in ventilated patients who develop ventilator-associated pneumonia (VAP) are important. Since MRSA are the most frequently isolated bacteria in patients with VAP, and a significant cause of morbidity and mortality in intubated patients, rapid diagnosis and early treatment could reduce mortality. This review will examine preventive steps (i.e. screening ventilated patients for MRSA, decolonization, and hand washing), assessing clinical presentations before the results of culture are obtained to direct empiric treatment, and the appropriate antibiotic therapy upon culture confirmation of MRSA that could help in the management of VAP.