BackgroundStreptococcus pneumoniae remains a major cause of childhood morbidity and mortality worldwide. Nasopharyngeal colonization plays an important role in the development and transmission of pneumococcal diseases, and infants and young children are considered to be the main reservoir of this pathogen. The aim of this study was to evaluate the rates and characteristics associated with nasopharyngeal carriage, the distribution of serotypes and the antimicrobial resistance profiles of Streptococcus pneumoniae among children in a large metropolitan area in Brazil before the introduction of the 10-valent pneumococcal conjugate vaccine.MethodsBetween March and June 2010, nasopharyngeal swabs were collected from 242 children aged <6 years attending one day care center and the emergency room of a pediatric hospital. Pneumococcal isolates were identified by conventional methods and serotypes were determined by a sequential multiplex PCR assay and/or the Quellung reaction. The antimicrobial susceptibilities of the pneumococci were assessed by the disk diffusion method. MICs for erythromycin and penicillin were also performed. Erythromycin resistance genes were investigated by PCR.ResultsThe overall colonization rate was 49.2% and it was considerably higher among children in the day care center. Pneumococcal carriage was more common among day care attenders and cohabitants with young siblings. The most prevalent serotypes were 6B, 19F, 6A, 14, 15C and 23F, which accounted for 61.2% of the isolates. All isolates were susceptible to clindamycin, levofloxacin, rifampicin and vancomycin. The highest rate of non-susceptibility was observed for sulphamethoxazole-trimethoprim (51.2%). Penicillin non-susceptible pneumococci (PNSP) accounted for 27.3% of the isolates (MICs of 0.12-4 μg/ml). Penicillin non-susceptibility was strongly associated with serotypes 14 and 23F. Hospital attendance and the presence of respiratory or general symptoms were frequently associated with PNSP carriage. The two erythromycin-resistant isolates (MICs of 2 and 4 μg/ml) belonged to serotype 6A, presented the M phenotype and harbored the mef(A/E) gene.ConclusionsCorrelations between serotypes, settings and penicillin non-susceptibility were observed. Serotypes coverage projected for the 10-valent pneumococcal conjugate vaccine was low (45.5%), but pointed out the potential reduction of PNSP nasopharyngeal colonization by nearly 20%.

Streptococcus agalactiae [β-haemolytic group B streptococci (GBS)] is a component of human intestinal and genitourinary microflora. This species is frequently related to illness in newborns, causing life-threatening diseases such as meningitis and bacteremia and is associated with complications during pregnancy and the post-partum period. GBS colonisation of the maternal genital tract has been considered the most important risk factor for neonatal disease development (Schuchat & Wenger 1994). GBS is also responsible for infections in older infants and non-pregnant adults, especially the elderly or those with any underlying medical conditions. Clinical manifestations include urinary tract infections, skin or soft tissue infections, osteomyelitis and bacteremia (Sendi et al. 2008). Points of concern include the increasing frequency of infections outside the perinatal period and a higher proportion of mortality in adults compared to the neonatal group (Phares et al. 2008).GBS has been continuously susceptible to penicillin and other β-lactams. However, resistance to antimicrobials used as alternative therapy, especially macrolides, lincosamides and fluoroquinolones has been documented in different countries (Duarte et al. 2005, Tazi et al. 2008, Pinheiro et al. 2009). One of the most common macrolide resistance mechanisms in streptococci is ribosomal modification by methylases, which are encoded by the erm genes. These enzymes also confer inducible or constitutive resistance to lincosamides and streptogramin B, which characterises macrolide-lincosamidestreptogramin B (MLS B ) phenotypes. Another common mechanism is drug efflux by a membrane-bound protein encoded by the mef gene, which is associated with the M phenotype (de Azavedo et al. 2001). Resistance to fluoroquinolones in GBS was first described in 2003 and is associated with point mutations in gyrA and parC genes (Kawamura et al. 2003).Despite the clinical impact of GBS infections and increasing resistance rates to some antimicrobials, there are a limited number of studies reporting antimicrobial resistance profiles among GBS strains circulating in Brazil, even from asymptomatic colonisation or clinical infection. In this study, 100 strains of S. agalactiae, isolated from genitourinary tract specimens from non-pregnant individuals during January 2008-August 2009 in the metropolitan area of Rio de Janeiro, were tested for antimicrobial susceptibility and the presence of macrolide resistance genes. The genetic diversity of erythromycin resistant isolates was evaluated using randomly amplified polymorphic-polymerase chain reaction (RAPD-PCR). SUBJECTS, MATERIALS AND METHODSStrains -One hundred S. agalactiae isolates from genitourinary tract specimens processed in a clinical laboratory in the metropolitan area of Rio de Janeiro during January 2008-August 2009 were included this study. The specimens [vaginal secretions (n = 49), urine (n = 30), sperm (n = 17) and other secretions (n = 4)] were obtained from non-pregnant individuals (73 females and 27 males, with ...

The phenotypic and genotypic characteristics of 25 Streptococcus porcinus isolates recovered from human sources were investigated and compared to the characteristics of 17 reference strains obtained from nonhuman sources. All of the S. porcinus isolates were beta-hemolytic (wide zones), susceptible to vancomycin, gave positive results for the leucine aminopeptidase and L-pyrrolidonylarylamidase tests, and produced acids from mannitol and sorbitol. Most of them were positive for the CAMP test and resistant to bacitracin. The isolates were susceptible to most of the 14 antimicrobials tested, except for tetracycline, for which 80% of the human isolates and 35.2% of the nonhuman strains were resistant. The tet(M) and the tet(O) genes were detected in 23 (88.5%) and 8 (30.8%) of the 26 tetracycline-resistant isolates, respectively. Analysis of whole-cell protein profiles obtained after sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a high similarity among the profiles. Chromosomal DNA was analyzed by pulsed-field gel electrophoresis (PFGE) after digestion with SmaI and by random(ly) amplified polymorphic DNA (RAPD)-PCR using primer 1254. Analysis of SmaI-restricted genomic DNA revealed the substantial genetic diversity among S. porcinus isolates from nonhuman sources, which were also serologically more diverse. Most of the human isolates belonged to serogroup NG1 and shared highly related PFGE profiles that were distinct from profiles of isolates from nonhuman sources. These results were in agreement with those obtained by analysis of amplicons after RAPD-PCR, indicating the potential ability of these techniques for typing S. porcinus and suggesting the occurrence of a few clonal groups of S. porcinus strains adapted to the human host.

Seventy-two strains of pediococci isolated from human clinical sources were characterized by conventional physiological tests, chromogenic enzymatic tests, analysis of whole-cell protein profiles (WCPP) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and analysis of chromosomal DNA restriction profiles by pulsed-field gel electrophoresis (PFGE). Conventional tests allowed identification of 67 isolates: 52 strains were identified as Pediococcus acidilactici, 15 strains were identified as Pediococcus pentosaceus, and 5 strains were not identified because of atypical reactions. Analysis of WCPP identified all isolates since each species had a unique WCPP. By the WCPP method, the atypical strains were identified as P. acidilactici (two strains) and P. pentosaceus (three strains). The chromogenic substrate test with o-nitrophenyl-␤-D-glucopyranoside differentiated all 54 strains of P. acidilactici (negative reactions) and 13 (72%) of 18 strains of P. pentosaceus (positive reactions). Isolates of both species were shown to be nonclonal as revealed by the genetic diversity when chromosomal DNA was analyzed by PFGE. Using WCPP as the definitive identification procedure, P. acidilactici (28 of 54 strains; 51.8%) was more likely than P. pentosaceus (4 of 18 strains; 22.3%) to be isolated from blood cultures.

In the present study, 37 group A Streptococcus (GAS) strains belonging to 13 new emm sequence types identified among GAS strains randomly isolated in Brazil were characterized by using phenotypic and genotypic methods. The new types were designated st204, st211, st213, st809, st833, st854, st2904, st2911, st2917, st2926, st3757, st3765, and st6735. All isolates were susceptible to the antimicrobial agents tested, except to tetracycline. They all carried the speB gene, and 94.6% produced detectable SpeB. Most strains belonging to a given emm type had similar or highly related pulsed-field gel electrophoresis profiles that were distinct from profiles of strains of another type. The other characteristics were variable from isolate to isolate, although some associations were consistently found within some emm types. Unlike the other isolates, all type st213 isolates were speA positive and produced SpeA. Strains belonging to st3765 were T6 and opacity factor (OF) negative. Individual isolates within OF-positive emm types were associated with unique sof gene sequence types, while OF-negative isolates were sof negative by PCR. This report provides information on new emm sequence types first detected in GAS isolates from a geographic area not extensively surveyed. Such data can contribute to a better understanding of the local and global dynamics of GAS populations and of the epidemiological aspects of GAS infections occurring in tropical regions.Streptococcus pyogenes, frequently referred to as group A Streptococcus (GAS), is a significant cause of human morbidity worldwide, and it is associated with a variety of mild and severe diseases that may occur either in areas where the diseases are endemic or as epidemics (10). Most of the knowledge that has been accumulated concerning GAS epidemiology is based upon serologic M and T typing. However, many GAS isolates are nontypeable due to the lack of appropriate type-specific antisera or possibly due to loss of antigen expression under cultivation. In recent years, DNA sequencing-based methods for characterizing GAS strains have been used, including sequence analysis of emm gene-specific PCR products (emm typing) (1, 2). This methodology has allowed the recognition of several previously unknown GAS types in different geographic areas, demonstrating the usefulness of emm typing for detecting genetic diversity among GAS isolates and for tracing GAS infections (1, 2, 5). A complementary molecular methodology (sof typing) is also based upon sequence analysis of a hypervariable virulence gene (3).In the present study, we describe the characteristics of GAS isolates belonging to new emm types identified among strains recovered from patients living in Brazil. These strains were further characterized through phenotypic tests (T-protein typing, detection of opacity factor [OF], antimicrobial susceptibility, and production of streptococcal pyrogenic exotoxin A [SpeA] and SpeB) and additional genotypic tests (the presence of speA, speB, speC, and sof gene PCR products, sof sequence typ...