Methicillin-resistant Staphylococcus aureus nasal carriage in neonates and children attending a pediatric outpatient clinics in Brazil

Methicillin-resistant and methicillin-sensitive Staphylococcus aureus isolates from skin and nares of Brazilian children with atopic dermatitis demonstrate high level of clonal diversity

BACKGROUND

Atopic dermatitis (AD) primarily affects the pediatric population, which is highly colonized by S. aureus. However, little is known about the genetic features of this microorganism and other staphylococcal species that colonize AD patients.

OBJECTIVE

This study aimed to characterize Staphylococcus spp. isolated from the nares and skin (with and without lesion) of 30 AD and 12 non-AD Brazilian children.

METHODS

Skin and nasal swabs were cultured onto mannitol salt agar, and bacterial colonies were counted and identified by matrix assisted laser desorption ionization time of flight mass spectrometry and polymerase chain reaction (PCR). Antimicrobial susceptibility was evaluated by phenotypic and genotypic tests. In S. aureus isolates, Panton-Valentine leukocidin genes were detected by PCR, and their clonality was assessed by pulsed-field gel electrophoresis and multilocus sequence typing.

RESULTS

S. aureus was more prevalent in the nares (P = 0.005) and lesional skin (P = 0.0002) of children with AD, while S. hominis was more frequent in the skin of non-AD children (P < 0.0001). All children in the study, except one from each group, were colonized by methicillin-resistant coagulase-negative Staphylococcus and 24% by methicillin-resistant S. aureus. Despite the great clonal diversity of S. aureus (18 sequence types identified), most AD children (74.1%) were colonized by the same genotype in both niches.

CONCLUSION

High colonization by polyclonal S. aureus isolates was found among children with AD, while S. hominis was more frequent among non-AD children. The high prevalence of methicillin-resistant staphylococcal isolates highlights the importance of continued surveillance, especially when considering empiric antibiotic therapy for the treatment of skin infections in these patients.

The History of Methicillin-Resistant Staphylococcus aureus in Brazil

Since the emergence of MRSA in the 1960s, a gradual increase in infections by resistant bacteria has been observed. Clinical manifestations may vary from brand to critical condition due to host risk factors, as well as pathogen virulence and resistance. The high adaptability and pathogenic profile of MRSA clones contributed to its spread in hospital and community settings. In Brazil, the first MRSA isolates were reported in the late 1980s, and since then different genetic profiles, such as the Brazilian epidemic clone (BEC) and other clones considered a pandemic, became endemic in the Brazilian population. Additionally, Brazil's MRSA clones were shown to be able to transfer genes involved in multidrug resistance and enhanced pathogenic properties. These events contributed to the rise of highly resistant and pathogenic MRSA. In this review, we present the main events which compose the history of MRSA in Brazil, including numbers and locations of isolation, as well as types of staphylococcal cassette chromosome mec (SCCmec) found in the Brazilian territory.

Molecular characterization of methicillin-resistant and methicillin-sensitive Staphylococcus aureus isolates from human milk samples in Brazil

Human milk is the best nutrient for infants. The donor human milk is stored in a milk bank before pasteurization. However, the human milk is not sterile and could be colonized with different types of bacteria. Many studies have shown S. aureus to be the most prevalent potential pathogen detected in human milk. This study characterized 22 methicillin-resistant and methicillin-sensitive Staphylococcus aureus isolates from raw human milk for the presence of virulence genes and agr type. Moreover, the genotypic as identified characterization was realized. The presence of virulence genes sei, seg, sec, seh, and etb was identified in resistant and sensitive strains. We observed the predominance of agr type II. The presence of SCCmec IV (67%, 4/6) and V (33%, 2/6) characterized resistant strains as CA-MRSA. Endemic lineages detected (ST1635/CC5-t002, ST5/CC5-t002, ST72/CC5-t126, ST1/CC1-t127, ST45/CC45-t065, and ST398/t1451) could be related to epidemic clones, such as USA800/ST5, USA700/ST72, USA400/ST1, USA600/ST45, and ST398. This study made it possible to understand the characteristics of virulence and clonality of some strains that circulate in breast milk in our region. The discovery of human milk colonization by MSSA and MRSA strains with molecular characteristics similar to infectious clones spread globally demonstrates the importance of monitoring strains that can spread and cause serious infections.

SCCmec Genotypes of Methicillin-Resistant Staphylococcus aureus in Nasal Carriage of Multiple Sclerosis Patients in Iran

BACKGROUND

Asymptomatic nasal colonization of Methicillin-Resistant Staphylococcus aureus is common in Multiple Sclerosis patients. SCCmec types I to III are mainly attributed to HA-MRSA strains whereas SCCmec types IV and V have commonly been reported in CA-MRSA infections. Here, we assessed the frequency of nasal carriage of MRSA in MS patients. This study aimed to evaluate MRSA SCCmec typing in MS nasal carriage.

METHODS

A cross-sectional descriptive study was conducted from Feb and Jun 2017 in MS Research Center, Tehran University of Medical Sciences (TUMS), Iran. Overall, 620 nasal swabs were collected (325 from MS patients and 295 from control group). Antimicrobial susceptibility test was performed using the disk diffusion and E-test method. Presence of mecA gene was confirmed by PCR assay and multiplex PCR was performed for SCCmec typing of MRSA isolates.

RESULTS

The frequency of MRSA among the MS patients and control group was almost equal (9.2% and 10.1%, respectively). SCCmec typing detected only types III, IV and V in both groups and type IV was the most predominant type in MS patients and control group. SCCmec type III was more prevalent in control group than MS patients (40% vs. 20%). Moreover, the frequency of SCCmec type V in MS patients was significantly higher than control group (36.7% vs. 3.3%).

CONCLUSION

Although most MRSA isolates were collected from inpatients, interestingly there is a high frequency of SCCmec types IV and V in MS group. Moreover, MRSA isolates were not resistant to more antibiotics in SCCmec type III than types IV-V.

Clonal Lineage Diversity, Antibiotic Resistance, and Virulence Determinants Among Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Isolated from Nurses at a Teaching Hospital in Ilam, Iran: Successful Nares Decolonization by Mupirocin

BACKGROUND

Staphylococcus aureus is known to be responsible for nosocomial infections, and the typing method was useful in managing the reservoir of bacteria. The main aim of this study was to determine the prevalence of S. aureus in the nares and hands of nurses working in Imam Khomeini hospital, Ilam, Iran, as well as to determine the clonal relatedness, antimicrobial susceptibility profiles, different virulence, and resistance determinants among these isolates. The evolution of mupirocin activity in the eradication of methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) colonization in the nares of the healthcare workers in Ilam, Iran, was also determined in this study.

MATERIALS AND METHODS

In this cross-sectional study, 80 nurses, auxiliary nurses, and service workers from Imam Khomeini Hospital were enrolled. MRSA, antibiotic susceptibility, and virulence determinants were evaluated. Then, the isolates were subjected to pulsed field gel electrophoresis (PFGE) and Staphylococcal cassette chromosome mec typing.

RESULTS

Our results demonstrated that 23% of isolates were MRSA. PFGE results demonstrated that pulsotypes A (3 out of 30; 10%) and J (3 out of 30; 10%), pulsotypes E (2 out of 30; 6.7%), M (2 out of 30; 6.7%), P(2 out of 30; 6.7%), and V (2 out of 30; 6.7%) were the most predominant pulsotypes, respectively.

CONCLUSION

We cannot give conclusive suggestions about the correlation between nasal carriage and infections, but we suggest the monitoring of all healthcare workers annually, decontamination of their noses by using mupirocin and other antistaphylococcal agents, and also the washing of their hands at least every 2 h.

Characterization of Staphylococcus aureus isolated from patients with burns in a regional burn center, Southeastern China

Background

S.aureus is a predominant pathogen that causes infection in critically ill patients, but little information exists regarding the characterization of S. aureus from different sources in burn patients in southeastern China.

Methods

We enrolled 125 patients with S. aureus infection in burns center between Jan 2014 and Dec 2015. S. aureus isolates were characterized by antimicrobial susceptibility test, toxin gene detection, and molecular typing with multilocus sequence type, staphylococcal protein A (spa) type, and staphylococcal cassette chromosome mec (SCCmec) type.

Results

Sixty-eight MRSA were isolated from SSTI and 31 from non-SSTI patients, respectively. Overall, the drug-resistant ability of S. aureus isolated from SSTI was higher than that from non-SSTI groups. SCCmecIII-CC239-t030 was the most common clone (38 from SSTIs, and 8 from non-SSTIs). Seg was the most common enterotoxin gene (21 from SSTIs and 33 from non-SSTIs). Isolates from SSTIs was more likely to carry seb (P = 0.04), while those from non-SSTIs tended to carry sea and seg (P = 0.002 and 0.01, respectively). Although isolates carried four hemolysin genes, there was no significant difference between them (P > 0.05).

Conclusion

SCCmecIII-CC239-t030 was the most common clone in Jiangxi burns center, China. The molecular characterization of S. aureus was quite different between SSTI and non-SSTI groups.

Prevalence of Nasal colonization with Staphylococcus aureus in 4 cities in Peru

Background

Antimicrobial resistance (AMR) is a growing public health threat around the world and is not well characterized in the developing setting. Specifically, there is a lack of information regarding nasal colonization with S. aureus and methicillin-resistant Staphylococcus aureus (MRSA) in Latin America and Peru.

Methods

This is the report of the baseline findings of a prospective cohort study followed up over 1 year at four geographically and ecologically distinct Peruvian Air Force bases in order to determine S. aureus nasal colonization prevalence and risk factors. Additionally, all MRSA isolates underwent molecular analysis which included pulsed-field gel electrophoresis and determination of virulence and resistance genes.

Results

We enrolled 756 military personnel. Anterior nares colonization with Staphylococcus aureus was detected in 73 of 756 participants (9.7 %) and MRSA was detected in 2 of 756 (0.3 %). Colonization rates differed significantly (P = 0.02) between geographic enrollment sites: Talara-4.3 %, Iquitos-9.1 %, Arequipa-14.0 % and Lima-11.3 %. Risk factors for S. aureus colonization included being male and a reported history of respiratory disease.

Conclusion

Overall, we found low prevalence of S. aureus and MRSA nasal colonization in this Peruvian military population. These findings contribute to the overall epidemiological understanding of S. aureus and MRSA in Latin America. The colonization rates which varied based on geographical location warrants further study.

Complete genome sequence of an agr-dysfunctional variant of the ST239 lineage of the methicillin-resistant Staphylococcus aureus strain GV69 from Brazil

Staphylococcus aureus is a versatile Gram-positive coccus frequently found colonizing the skin and nasal membranes of humans. The acquisition of the staphylococcal cassette chromosome mec was a major milestone in the evolutionary path of methicillin-resistant S. aureus. This genetic element carries the mecA gene, the main determinant of methicillin resistance. MRSA is involved in a plethora of opportunistic infectious diseases. The accessory gene regulator is the major S. aureus quorum sensing system, playing an important role in staphylococcal virulence, including the development of biofilms. We report the complete genome sequence (NCBI BioProject ID: PRJNA264181) of the methicillin-resistant S. aureus strain GV69 (= CMVRS P4521), a variant of the ST239 lineage that presents with a natural attenuation of agr-RNAIII transcription and a moderate accumulation of biofilm.

Staphylococcus aureus isolates colonizing and infecting cirrhotic and liver-transplantation patients: comparison of molecular typing and virulence factors

BACKGROUND

S. aureus is an important agent of colonization and infection in liver transplant patients. It harbors several virulence factors that can increase its pathogenicity. However, studies of virulence and molecular typing of MRSA in cirrhotic and liver transplantation patients are scarce.

RESULTS

Here we use SCCmec, PFGE, spa typing, MLST and virulence factors to characterize MRSA isolates in pre and post liver transplantation patients. Sixteen (13%) of 126 cirrhotic and 15 of the 64 liver-transplanted patients (23%) were colonized by MRSA (p=0.091). SCCmec types I, II and III that are generally associated with nosocomial infections were identified in 91% of the isolates. None of the isolates carried PVL, adhesion factors and fib gene. Only three MRSA colonized isolates carried tst gene and were characterized as SCCmec type I and t149. Ten spa types and five STs were identified; t002 and ST105 were the most frequent profiles. Spa types and ST1510 never described in Brazil and a new spa type t14789 were identified. Nineteen PFGE subtypes were found and grouped into nine types. There was a predominant cluster, which was related to the New York/Japanese epidemic clone and harboured SCCmec type II identified in both cirrhotic and post-transplantation patients. Based on SCCmec and virulence factors the MRSA isolates belonged to NY/Jpn clone seen be more similar to the USA100 MRSA isolates.

CONCLUSIONS

Although without significance, liver-transplantation was more frequently colonized by MRSA than cirrhotic patients. The most frequent SCCmec was type II, and the predominant cluster was related to the New York/Japanese clone. A new spa t14789, and ST1510 never reported in Brazil were identified.

Characterization of the clonal profile of MRSA isolated in neonatal and pediatric intensive care units of a University Hospital

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) are important pathogens in neonatal and pediatric intensive care units, which can cause severe infections in hospitalized children. Detection of the mecA gene and classification of the staphylococcal cassette chromosome mec (SCCmec) permit the characterization of MRSA strains isolated from infections caused by these microorganisms. In contrast, pulsed-field gel electrophoresis (PFGE) is used to type MRSA clones. This method is commonly used to analyze the epidemiology of bacteria causing nosocomial infections. The objective of this study was to detect and characterize MRSA isolated from clinical specimens of children hospitalized in the neonatal and pediatric intensive care units of the University Hospital of the Botucatu Medical School.

METHODS

A total of 119 S. aureus strains were isolated from clinical specimens and the mecA gene was detected by PCR. SCCmec was detected by multiplex PCR and the clonal profile was analyzed by PFGE.

RESULTS

The mecA gene was detected in 17.6% (21/119) of the isolates; 42.9% (9/21) of MRSA were characterized as SCCmec type III and 57.1% (12/21) as type IV. Analysis of the clonal profile of these strains revealed three distinct clones, with SCCmec type III being related to the Brazilian endemic clone and type IV to clones JCSC4469 and USA800.

CONCLUSIONS

Replacement of clonal groups occurred in the neonatal and pediatric units over the period studied, a fact highlighting the importance of improving hygiene practices and control measures of nosocomial infections in these units.

Non-multidrug-resistant, methicillin-resistant Staphylococcus aureus in a neonatal unit

BACKGROUND

In the last decade, non-multiresistant methicillin-resistant Staphylococcus aureus (NM-MRSA) has been described as an important agent in bloodstream infections in our hospital.

METHODS

This prospective cohort study, conducted from February 2009 through January 2010 in the neonatal unit, evaluated 403 newborns (NB), their 382 mothers and 148 health care workers (HCW).

RESULTS

Approximately 217 NB (54%), 187 mothers (48%) and 87 HCW (59%) were colonized by S. aureus (SA). MRSA colonization was greater among NB (15%) than mothers (4.7%) and HCW (3.4%). Although mother-to-NB transmission occurred, in most cases mothers were not responsible for NB colonization. There were 2 predominant PFGE patterns among the NB and some mothers and HCW became colonized by them. Factors significantly associated with MRSA carriage by NB were lower level of maternal schooling (risk factor: odds ratio: 2.99; 95% confidence interval: 1.10-8.07) and maternal rhinosinusitis (protective factor: odds ratio: 0.33; 95% confidence interval:0.12-0.88). Among NB who remained hospitalized for more than 72 hours, breast feeding was protective (odds ratio: 0.22; 95% confidence interval: 0.05-0.98). All the isolates were NM-MRSA, carried few virulence factors and SCCmec types IVa and type IVd predominated.

CONCLUSIONS

Although there were no cases of infection, nosocomial transmission of MRSA clearly occurred in the neonatal unit, and this highlights the need for infection control practices such as hand hygiene to prevent cross-dissemination. Other healthcare practices, which are very basic but also ample in scope, may play a role, such as general education of women and breast feeding.