Maria Cícera Silva-Carvalho

First Report of Infection with Community-Acquired Methicillin-Resistant Staphylococcus aureus in South America

ABSTRACT Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has recently emerged in the southwestern Pacific, North America, and Europe. These S. aureus isolates frequently shared some genetic characteristics, including the SCCmec type IV and lukS-lukF genes. In this paper we show that typical CA-MRSA isolates have spread to South America (Brazil).

The Predominant Variant of the Brazilian Epidemic Clonal Complex of Methicillin-Resistant Staphylococcus aureus Has an Enhanced Ability to Produce Biofilm and to Adhere to and Invade Airway Epithelial Cells

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a therapeutic problem. In the present study, the molecular characterization by pulsed-field gel electrophoresis of MRSA isolates collected from a university hospital revealed that the predominant variant of the Brazilian epidemic clonal complex (BECC) was responsible for the increase in the incidence of MRSA strains, which reached 28% in 1998. It was verified that this predominant variant of the BECC displayed an enhanced ability to produce biofilm on inert polystyrene surfaces and to adhere to and invade epithelial airway cells. These results indicate that MRSA strains belonging to the BECC have evolved advantageous properties that might play a role in their predominance as international nosocomial pathogens.

Isolation of methicillin-resistant coagulase-negative staphylococci from patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and comparison of different molecular techniques for discriminating isolates of Staphylococcus epidermidis

Coagulase-negative staphylococci (CNS) have emerged as an important pathogen in nosocomial infections. About 80%-90% of CNS isolates associated with hospital infections are methicillin-resistant coagulase-negative staphylococci (MRCNS). The aims of this study were to screen for MRCNS isolates in the flora of a small population of patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and to evaluate the discriminatory power of different molecular methods: pulsed-field gel electrophoresis (PFGE), mecA location, ClaI/mecA polymorphism and arbitrarily primed polymerase chain reaction (AP-PCR) for characterizing isolates of methicillin-resistant Staphylococcus epidermidis (MRSE). Seventy-nine CNS isolates were recovered from the 11 CAPD patients studied. Using a methicillin screening agar and a DNA specific mecA probe we verified that 30 of the 79 (38%) CNS isolates were resistant to methicillin (MRCNS). Twenty-two of the 30 MRCNS (73%) were MRSE, 7 (23%) methicillin-resistant S. haemolyticus (MRSH(ae)) and 1 (3%) methicillin-resistant S. hominis (MRSH(om)). All patients analyzed carried MRCNS in their flora, in one or more sites. Since CAPD patients have high risk for developing peritonitis, the colonization of these patients with MRCNS might represent an additional problem, due to the therapeutic restrictions imposed by these multiresistant isolates. A wide genetic diversity was verified when the PFGE of the MRSE isolates was analyzed. The 22 MRSE isolates displayed a total of 15 PFGE different patterns (11 PFGE types and 4 subtypes). The location of mecA in the SmaI-fragmented genome DNA did not bring any additional advantage for epidemiologic characterization of the isolates. The ClaI/mecA polymorphism was able to correctly discriminate 12 from the 15 PFGE patterns. In addition, the DNA of 20 MRSE isolates were used for AP-PCR typing. These isolates belonged to 14 PFGE patterns (11 types and 3 subtypes) and displayed 15 genotypes (for the association of PFGE, mecA location and ClaI/mecA polymorphism). A total of 17 different amplification patterns was verified using the primer 1. Only for 2 genotypes, strains having identical genetic backgrounds were further discriminated by AP-PCR (2 of 15 genotypes (87%) for AP-PCR and 1 of 15 genotypes for PFGE; (93%). Concluding, our results indicated that the AP-PCR can be an alternative and useful tool for monitoring and genotyping MRSE colonization and also to molecular characterizing MRSE outbreaks in hospitals.

The first report in Brazil of severe infection caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA)

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emergent pathogen in Brazil. However, there are no data on the prevalence of CA-MRSA. We report here the first well-characterized case of severe life-threatening CA-MRSA infection in a child living in Rio de Janeiro city. The patient had many complications including hematogenous osteomyelitis and involvement of multiple sites requiring drainage of soft-tissue abscess, and pleural and pericardial empyema. The MRSA isolates recovered were genotyped using PFGE, SCCmec typing and multilocus sequence typing. Disk diffusion tests were performed following Clinical and Laboratory Standards Institute recommendations. In addition, the presence of Panton-Valentine leukocidin (PVL) was assessed by PCR amplification, using specific primers for lukF-pv (encoding for the F subunit of the PVL). The bacterial isolates were related to the ST30-SCCmecIV lineage (Oceania Southwest Pacific clone), a PVL producer CA-MRSA previously detected in Porto Alegre, RS, Brazil. Also, the isolates analyzed were susceptible to all non-beta-lactam antibiotics tested. The present report demonstrates that disseminated CA-MRSA disease is also occurring in Rio de Janeiro. Thus, the empirical treatment of moderate or severe infections suspected of being associated with CA-MRSA needs to be reviewed in order to allow prompt initiation of an effective therapy that also covers these microorganisms.

Emergence of multiresistant variants of the community-acquired methicillin-resistant Staphylococcus aureus lineage ST1-SCCmecIV in 2 hospitals in Rio de Janeiro, Brazil.

Usually, community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is susceptible to a variety of non-beta-lactam drugs. These isolates commonly display SCCmecIV and are associated with community-acquired infections. More recently, CA-MRSA has been isolated from health-care-associated diseases. We characterized MRSA isolates from 2 hospitals in Rio de Janeiro area to assess the entry of new lineages. The isolates were primary genotyped using a combination of molecular typing methods including SCCmec, restriction modification test, and Panton-Valentine leukocidin (PVL) detection. Pulsed-field gel electrophoresis was carried out for representatives of each lineages found. Disk diffusion test was performed as recommended by the Clinical and Laboratory Standards Institute. SCCmecIV was the predominant cassette mec detected. The most frequent MRSA lineage, a PVL nonproducer, was allocated in the CC1-SCCmecIV. It was found that 56% of these isolates were resistant to 3 or more non-beta-lactam drugs. Multilocus sequence typing of a representative of the CC1 isolates supported our finds that multiresistant variants of a CA-MRSA lineage (ST1-SCCmecIV) emerged in this city.

Clinical and molecular epidemiology of methicillin-resistant Staphylococcus aureus carrying SCCmecIV in a university hospital in Porto Alegre, Brazil

We evaluated clinical outcomes and molecular epidemiology of methicillin-resistant Staphylococcus aureus carrying SCCmecIV recovered from patients who attended at a teaching hospital from Porto Alegre, Brazil. All Panton-Valentine leukocidin (PVL)-producer isolates belonged to clonal complex (CC) 30 (11 isolates, related to Oceania Southwest Pacific clone [OSPC]), and the PVL-negative isolates were typed as CC5 (2 isolates, related to the pediatric clone). Five patients had health care-associated infections (HCAIs) with hospital-onset, 5 HCAIs with community-onset, and 3 community-acquired infections without risks. A high overall mortality (30.8%) was found. This study show that OSPC isolates are not only causing community-associated infections but are also involved in HCAI in our country.

First report in South America of companion animal colonization by the USA1100 clone of community-acquired meticillin-resistant Staphylococcus aureus (ST30) and by the European clone of methicillin-resistant Staphylococcus pseudintermedius (ST71)

BackgroundMethicillin-resistant staphylococci can colonize and cause diseases in companion animals. Unfortunately, few molecular studies have been carried out in Brazil and other countries with the aim of characterizing these isolates. Consequently, little is known about the potential role of companion animals in transmitting these resistant bacteria to humans. In this work we searched for mecA gene among Staphylococcus isolates obtained from nasal microbiota of 130 healthy dogs and cats attended in a veterinary clinic located in the west region of Rio de Janeiro. The isolates recovered were identified to the species level and characterized using molecular tools.ResultsA community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolate related to USA1100 (Southwest Pacific clone) and susceptible to all non-β-lactams was detected in a cat (1.7%, 1/60). Another coagulase-positive isolate harboring mecA was recovered from a dog (1.4%, 1/70) and identified as Staphylococcus pseudintermedius (MRSP) related to the European clone (ST71). The two isolates of Staphylococcus conhii subsp. urealyticus (1.4%, 1/70 dogs and 1.7%, 1/60 cats), similarly to the MRSP isolate, also presented high-level multiresistance. The majority of the methicillin-resistant coagulase-negative staphylococci recovered were Staphylococcus saprophyticus (5.7%, 4/70 dogs and 6.7%, 4/60 cats) and all clustered into the same PFGE type.ConclusionsThis work demonstrates that mecA-harboring Staphylococcus isolates are common members of the nasal microbiota of the healthy companion animals studied (9.2%, 12/130 animals), including some high-level multiresistant isolates of S. pseudintermedius and S. conhii subsp. urealyticus. The detection, for the first time in South America, of USA1100-related CA-MRSA and of ST71 MRSP (European clone), colonizing companion animals, is of concern. Both S. pseudintermedius and S. aureus are important agents of infections for animals. The USA1100 CA-MRSA is a causative of severe and disseminated diseases in healthy children and adults. Additionally, MRSP is a nosocomial pathogen in veterinarian settings. It had already been demonstrated that the virulent ST71 MRSP is geographically spread over Europe and USA, with potential for zoonotic infections.

Molecular characterization of methicillin-resistant Staphylococcus aureus disseminated in a home care system.

OBJECTIVE To study colonization with methicillin-resistant Staphylococcus aureus in a home care service during a 4-month period. DESIGN Prospective study. SETTING A home care service located in Rio de Janeiro, Brazil. PARTICIPANTS Patients admitted to the home care service during this period, their household contacts, and health care workers (HCWs). METHODS Swab specimens from the anterior nares were collected from each patient in the 3 groups at admission. Screening was repeated every 7 days. MRSA was detected using a mecA probe, and the clonality of isolates was evaluated by molecular methods, primarily pulsed-field gel electrophoresis. RESULTS Of the 59 study patients, 9 (15.3%) had MRSA colonization detected; these cases of colonization were classified as imported. Only 1 (2.0%) of the 50 patients not colonized at admission became an MRSA carrier (this case of colonization was classified as autochthonous). Two (0.9%) of 224 household contacts and 16 (7.4%) of 217 HCWs had MRSA colonization. Cross-transmission from patient to HCW could be clearly demonstrated in 8 cases. The great majority of MRSA isolates belonged to the Brazilian epidemic clone. CONCLUSIONS MRSA colonization was common in the home care service analyzed. The fact that the majority of MRSA isolates obtained were primarily of nosocomial origin (and belonged to the so-called Brazilian epidemic clone) substantiated our findings that all but 1 patient had already been colonized before admission to the home care service. Only cross-transmission from patients to healthcare workers could be verified. On the basis of these results, we believe that a control program built on admission screening of patients for detection of MRSA carriage could contribute to the overall quality of care.

Genotyping of methicillin-resistant Staphylococcus aureus isolates obtained in the Northeast region of Brazil

Methicillin-resistant Staphylococcus aureus (MRSA) is a major agent of hospital infections worldwide. In Brazil, a multiresistant MRSA lineage (ST239-SCCmecIIIA), the so-called Brazilian epidemic clone (BEC), has predominated in all regions. However, an increase in nosocomial infections caused by non-multiresistant MRSA clones has recently been observed. In the present study, 45 clinical isolates of MRSA obtained from a university hospital located in Natal city, Brazil, were identified by standard laboratory methods and molecularly characterized using staphylococcal chromosome cassette mec (SCCmec) typing and pulsed-field gel electrophoresis. Antimicrobial susceptibility testing was carried out using CLSI methods. The MRSA isolates studied displayed a total of 8 different pulsed-field gel electrophoresis patterns (types A to H) with predominance (73%) of pattern A (BEC-related). However, MRSA harboring SCCmec type IV were also identified, 3 (7%) of which were genetically related to the pediatric clone--USA800 (ST5-SCCmecIV). In addition, we found a considerable genetic diversity within BEC isolates. MRSA displaying SCCmecIV are frequently susceptible to the majority of non-beta-lactam antibiotics. However, emergence of multiresistant variants of USA800 was detected.

Emergence of clonal complex 5 (CC5) methicillin-resistant Staphylococcus aureus (MRSA) isolates susceptible to trimethoprim-sulfamethoxazole in a Brazilian hospital

In this study, genotyping techniques including staphylococcal chromosomal cassette mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and restriction-modification tests were used to compare the molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered at two times within a 10-year interval (1998 and 2008) from a tertiary Brazilian hospital. In addition, the antimicrobial susceptibility profiles were analyzed. All 48 MRSA isolates from 1998 and 85.7% from 2008 (48/56 isolates) displayed multidrug-resistance phenotypes and SCCmec III. All but one of the 13 representative SCCmec III isolates belonged to CC8 and had PFGE patterns similar to that of the BMB9393 strain (Brazilian epidemic clone of MRSA; BEC). In 2008, we found an increased susceptibility to rifampicin and chloramphenicol among the SCCmec III isolates. In addition, we detected the entrance of diverse international MRSA lineages susceptible to trimethoprim-sulfamethoxazole (SXT), almost all belonging to CC5. These non-SCCmec III isolates were related to the USA300 (ST8-SCCmec IV; PFGE-type B), USA800 (ST5-SCCmec IV; subtype D1), USA100 (ST5-SCCmec II; subtype D2), and EMRSA-3/Cordobes (ST5-SCCmec I, type C) clones. To the best of our knowledge, this is the first report of the emergence of isolates genetically related to the EMRSA-3/Cordobes clone in southeast Brazil. In this regard, these isolates were the most common non-SCCmec III MRSA in our institution, accounting for 8.9% of all isolates recovered in 2008. Thus, despite the supremacy of BEC isolates in our country, significant changes may occur in local MRSA epidemiology, with possible consequences for the rationality of MRSA empiric therapy.