Biomedical subjects

Richard R Facklam

Publications and source records attributed to Richard R Facklam.

At least 19 recordsLinked to original sources

PubMed2006

Effect of introduction of the pneumococcal conjugate vaccine on drug-resistant Streptococcus pneumoniae.

BACKGROUND: Five of seven serotypes in the pneumococcal conjugate vaccine, introduced for infants in the United States in 2000, are responsible for most penicillin-resistant infections. We examined the effect of this vaccine on invasive disease caused by resistant strains. METHODS: We used laboratory-based data from Active Bacterial Core surveillance to measure disease caused by antibiotic-nonsusceptible pneumococci from 1996 through 2004. Cases of invasive disease, defined as disease caused by pneumococci isolated from a normally sterile site, were identified in eight surveillance areas. Isolates underwent serotyping and susceptibility testing. RESULTS: Rates of invasive disease caused by penicillin-nonsusceptible strains and strains not susceptible to multiple antibiotics peaked in 1999 and decreased by 2004, from 6.3 to 2.7 cases per 100,000 (a decline of 57 percent; 95 percent confidence interval, 55 to 58 percent) and from 4.1 to 1.7 cases per 100,000 (a decline of 59 percent; 95 percent confidence interval, 58 to 60 percent), respectively. Among children under two years of age, disease caused by penicillin-nonsusceptible strains decreased from 70.3 to 13.1 cases per 100,000 (a decline of 81 percent; 95 percent confidence interval, 80 to 82 percent). Among persons 65 years of age or older, disease caused by penicillin-nonsusceptible strains decreased from 16.4 to 8.4 cases per 100,000 (a decline of 49 percent). Rates of resistant disease caused by vaccine serotypes fell 87 percent. An increase was seen in disease caused by serotype 19A, a serotype not included in the vaccine (from 2.0 to 8.3 per 100,000 among children under two years of age). CONCLUSIONS: The rate of antibiotic-resistant invasive pneumococcal infections decreased in young children and older persons after the introduction of the conjugate vaccine. There was an increase in infections caused by serotypes not included in the vaccine.

Adolescent↗

PubMed2006

Enterococcus caccae sp. nov., isolated from human stools.

The National Antimicrobial Resistance Monitoring System Laboratory at the Centers for Disease Control and Prevention (CDC) isolated two enterococcus-like strains that were referred to the CDC Streptococcus Laboratory for further identification. The isolates were recovered from human stool samples collected on different occasions from the same individual in Portland (OR, USA) in July 2000. Conventional physiological tests distinguished these strains from all known species of enterococci. Analyses of whole-cell-protein electrophoretic profiles showed the same unique profile for the two isolates, being most similar those of Enterococcus moraviensis and Enterococcus haemoperoxidus albeit not close enough to allow conclusive inclusion in any enterococcal species. Both isolates gave positive results in tests using the AccuProbe Enterococcus genetic probe, and Lancefield extracts reacted with CDC group D antiserum. Comparative 16S rRNA gene sequencing studies also revealed that these strains were closely related to the species E. moraviensis (99.6 % identity). The results of DNA-DNA relatedness experiments confirmed that these strains represented a single novel taxon. The highest level of DNA-DNA relatedness found between the novel taxon and any of the currently recognized species of Enterococcus was 32 %, for both E. moraviensis and E. haemoperoxidus. On the basis of this evidence, it is proposed that these stool isolates constitute a novel species, for which the name Enterococcus caccae sp. nov. is proposed. The type strain is 2215-02(T) (=SS-1777(T)=ATCC BAA-1240(T)=CCUG 51564(T)).

Bacterial Proteins↗

PubMed2006

Characterization of group A streptococci (Streptococcus pyogenes): correlation of M-protein and emm-gene type with T-protein agglutination pattern and serum opacity factor.

Strain characterization of group A streptococci (GAS) has traditionally been based on serological identification of M protein. Additional tests to determine T-protein serotype and production of streptococcal serum opacity factor (SOF) provide important information both to aid in and to supplement M-protein serotyping. Advances in DNA-sequencing technology in the late twentieth century resulted in the development of a method for determining the M type of GAS from the sequence of the gene encoding M protein, the emm gene. Although emm-sequence typing has largely replaced M typing in many laboratories, information provided by T typing and SOF determination continues to provide valuable supplementary information for strain characterization. A comprehensive summary of the correlation of T pattern and SOF production with M type was last published in 1993, several years before emm typing became widely available. Since then, the ease of M-type identification afforded by emm typing has resulted in an increase in the number of confirmed M/emm types of more than 50 %. However, comprehensive information about T-protein serotype and the correlation of SOF production with these new M/emm types is not widely available. This report presents a comprehensive summary of this information, not only for newly described types, but also updated information for previously described types. This information was extracted from combined records from streptococcal reference laboratories at the University of Minnesota and at the Centers for Disease Control and Prevention in Atlanta. Data from more than 40,000 strains (representing uncomplicated GAS infections, systemic invasive infections and strains associated with non-suppurative sequelae, collected from the US and diverse locations worldwide) were analysed.

Agglutination↗

PubMed2006

Genetically diverse group A streptococci from children in far-western Nepal share high genetic relatedness with isolates from other countries.

The genetic diversity of group A streptococci (GAS) throughout much of the world has not been adequately explored. To assess genetic variation among GAS in western Nepal, 120 noninvasive GAS, collected from eight different villages, were genetically characterized using emm typing, sof sequencing, and multilocus sequence typing (MLST). A high level of genetic diversity was observed among these isolates, with 51 genotypes based upon 51 multilocus sequence types (STs), 45 emm sequence types, and 28 sof sequence types. On the basis of shared ST-emm and sof-emm associations, 40 of the 51 genotypes were identical or highly related to genotypes characterized from locations outside of Nepal, even though most of the emm sequence and clonal types are rare among GAS within the United States. When analyzing all known STs highly related to Nepal STs, only one example of similar STs shared between a sof PCR-positive strain and a sof PCR-negative strain was observed. Since previous data indicate free exchange of MLST loci between sof-positive and sof-negative strains, there is possibly selection against the expansion of subclones resulting from horizontal transfers of sof or emm genes between sof-positive and sof-negative strains. All 45 emm types encountered in Nepal have also been documented from other countries. These data, together with data encompassing the past decade of emm type surveillance, support the possibility that most existing GAS emm types have been discovered. Similarly, since most (40/51) strain types were highly related to strains found elsewhere, it is likely that a major fraction of the existing GAS clonal complexes have been discovered.

Antigens, Bacterial↗

PubMed2005

Increased prevalence of pediatric pneumococcal serotypes in elderly adults.

BACKGROUND: Pneumococcal disease is most prevalent among young children and elderly adults. We explored whether similarities exist in the serotypes that cause disease in these 2 high-risk groups. METHODS: With use of US population-based data from 1998-1999 (before the introduction of the 7-valent pneumococcal conjugate vaccine [PCV7] as routine immunization for infants) from the Centers for Disease Control and Prevention's Active Bacterial Core surveillance, we evaluated whether the rate of invasive pneumococcal disease caused by the pediatric serotypes (6B, 9V, 14, 19F, and 23F) increased among elderly persons. We adjusted for potential confounders in multivariable logistic regression. RESULTS: We analyzed 2987 pneumococcal isolates recovered from adults. The risk of infection with pediatric serotypes increased from 32.5% in 35-49-year-old persons to 51.2% in > or = 85-year-old persons (P < .001). Compared with 35-49-year-old persons, the risk of infection with pediatric serotypes was significantly elevated among 65-74-year-old persons (relative risk [RR], 1.68; 95% confidence interval [CI], 1.29-2.20) and increased progressively among persons aged 75-84 years (RR, 1.82; 95% CI, 1.41-2.36) and > or = 85 years (RR, 2.29; 95% CI, 1.72-3.05), with adjustment for sex, race, geographic location, underlying illness, and penicillin resistance. The rate of penicillin resistance was also elevated in the elderly population but was not significant after adjustment for serotype and race. CONCLUSIONS: The increased proportion of severe pneumococcal disease caused by pediatric serotypes in the elderly population might indicate opportunities for prevention with use of PCV7.

Adult↗

PubMed2005

Novel antibiotic-resistant pneumococcal strains recovered from the upper respiratory tracts of HIV-infected adults and their children in Kisumu, Kenya.

In a survey of genetic diversity within penicillin-nonsusceptible pneumococcal isolates in Kenya, we examined 162 upper respiratory isolates from 104 human immunodeficiency virus (HIV)-infected adults and 46 children in a cotrimoxazole prophylaxis study. Antibiotic resistance levels were high; 152 (94.4%) were cotrimoxazole nonsusceptible (134 fully resistant) and 124 (77%) were intermediately penicillin resistant. Isolates nonsusceptible to penicillin and cotrimoxazole (PNCNP) were found among 24 of the 29 serotypes encountered, 15 of which have rarely or never had documented nonsusceptibility to penicillin. These included serotypes 3, 4, 7C, 7F, 10A, 11A, 13, 15A, 15B, 16F, 17F, 19B, 21, 35A, and 35B. Segments of pbp2b genes from 9 PNCNP (serotypes 3, 13, 15A, 16F, 20, and 35A) were typical of resistance-conferring alleles in that they were highly divergent and contained two substitutions thought to be critical for resistance. Similarly, the dhfr genes from 3 PNCNP were divergent and contained a substitution required for cotrimoxazole resistance. Multilocus sequence typing (MLST) of 48 PNCNP revealed 33 sequence types (STs), none of which were previously recorded at http://www.mlst.net. Comparisons with all known STs revealed that 23 of these STs were unrelated to other known STs, whereas 10 STs were highly related to STs from internationally disseminated strains, including 2 of the 26 antibiotic-resistant clones recognized by the Pneumococcal Molecular Epidemiology Network. Based upon differing serotypes expressed by strains of identical or closely similar genotypes, there has been an extensive history of capsular switching within seven genetic clusters represented by these 10 STs and related STs described at http://www.mlst.net.

Adult↗

PubMed2005

Six-month multicenter study on invasive infections due to Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis in Argentina.

During a 6-month period, 95 invasive infections due to Streptococcus pyogenes and group C or group G Streptococcus dysgalactiae subsp. equisimilis were recorded from 40 centers of 16 cities in Argentina. We describe here epidemiologic data available for 55 and 19 patients, respectively, associated with invasive infections due to S. pyogenes and S. dysgalactiae subsp. equisimilis. The associated isolates and 58 additional pharyngeal isolates were genotyped and subjected to serologic and/or antibiotic susceptibility testing. Group A streptococcal emm type distribution and strain association with toxic shock appeared to differ somewhat from results found within the United States; however, serologic characterization and sof sequence typing suggested that emm types found in both countries are reflective of shared clonal types.

Adult↗

PubMed2005

Phenotypic and genotypic characteristics of Streptococcus porcinus isolated from human sources.

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.

Adolescent↗

PubMed2005

Erythromycin-nonsusceptible Streptococcus pneumoniae in children, 1999-2001.

After increasing from 1995 to 1999, invasive erythromycin-nonsusceptible Streptococcus pneumoniae rates per 100,000 decreased 53.6% in children from Baltimore, Maryland (US), from 1999 to 2001, which was partially attributed to strains related to the mefE-carrying England14-9 clone. The decline in infection rates was likely due to the pneumococcal 7-valent conjugate vaccine.

Anti-Bacterial Agents↗

PubMed2004

Impact of childhood vaccination on racial disparities in invasive Streptococcus pneumoniae infections.

CONTEXT: Historically, incidence of pneumococcal disease in the United States has been higher among blacks than among whites. Following recommendation of a new 7-valent pneumococcal conjugate vaccine for children in October 2000, the incidence of invasive pneumococcal disease has declined dramatically, but the impact of vaccination on racial disparities in incidence of pneumococcal disease is unknown. OBJECTIVE: To assess the effect of conjugate vaccine introduction on rates of pneumococcal disease among whites and blacks in the United States. DESIGN, SETTING, AND PATIENTS: Analysis of data from the Active Bacterial Core Surveillance (ABCs)/Emerging Infections Program Network, an active, population-based surveillance system in 7 states. Patients were 15,923 persons with invasive pneumococcal disease occurring between January 1, 1998, and December 31, 2002. MAIN OUTCOME MEASURES: Age- and race-specific pneumococcal disease incidence rates (cases per 100 000 persons), rate ratios, and rate differences. RESULTS: Between 1998 and 2002, annual incidence rates for invasive pneumococcal disease decreased from 19.0 to 12.1 cases per 100 000 among whites and from 54.9 to 26.5 among blacks. Due to these declines, 14,730 fewer cases occurred among whites and 8780 fewer cases occurred among blacks in the United States in 2002, compared with 2 prevaccine years, 1998 and 1999. Before vaccine introduction, incidence among blacks was 2.9 times higher than among whites (95% confidence interval [CI], 2.7-3.0); in 2002, the black-white rate ratio had been reduced to 2.2 (95% CI, 2.0-2.4). Incidence among black children younger than 2 years went from being 3.3 times higher (95% CI, 3.0-3.7) than among white children in the prevaccine period to 1.6 times higher (95% CI, 1.1-2.2) in 2002. By 2002, 74% of white children and 68% of black children aged 19 to 35 months in the 7 states had received at least 1 dose of pneumococcal conjugate vaccine; 43% of white and 39% of black children received 3 or more doses. CONCLUSION: Although blacks remain at higher risk of invasive pneumococcal disease, introduction of childhood pneumococcal vaccination has reduced the racial disparity in incidence of pneumococcal disease.

Adolescent↗

PubMed2004

Comparison of four polymerase chain reaction assays for specificity in the identification of Streptococcus pneumoniae.

We determined the usefulness of 4 conventional polymerase chain reaction (PCR) assays, lytA, psaA, and two primer sets from the ply gene, for accuracy in the discrimination of nontypeable (NT) Streptococcus pneumoniae from closely related atypical streptococci. The study used 100 strains. We compared the PCR results with laboratory tests that included optochin (ethylhydrocupreine hydrochloride) sensitivity, bile solubility, the Quellung reaction, and AccuProbe (Gen-Probe Inc., San Diego, CA). These latter tests did not discriminate the atypical streptococci from the NT pneumococci. All PCR primer sets amplified the NT pneumococcal isolates in agreement with the other laboratory tests. However, the IA and IB ply primers were positive for 8 of the 16 atypical streptococcal isolates, and the IIA and IIB ply primers amplified all atypical isolates. The psaA primers had only one discrepant result, a positive among the atypical streptococci. The lytA primers were the most specific with 100% specificity for all strains tested.

Adhesins, Bacterial↗

PubMed2004

Occurrence and Characteristics of Erythromycin-Resistant Streptococcus pneumoniae Strains Isolated in Three Major Brazilian States.

We investigated the occurrence and phenotypic and genotypic characteristics of erythromycin-resistant Streptococcus pneumoniae strains isolated in three major states in Brazil, from 1990 to 1999. Of the 931 pneumococcal strains evaluated, 40 (4.3%) were erythromycin-resistant (Ery-R). Among the 40 Ery-R strains, 90.0%, 80.0%, 27.5%, 5.0%, and 2.5% were resistant to tetracycline, trimethoprim-sulfamethoxazole, penicillin, chloramphenicol, and rifampin, respectively. None of the strains were resistant to ofloxacin or to vancomycin. Most [37 (92.5%)] of the 40 Ery-R isolates presented the MLS(B) phenotype and 3 (7.5%) strains showed the M phenotype. PCR testing indicated that all MLS(B) phenotype isolates harbored the erm(B) gene only, whereas the mef(A/E) gene was present in all isolates presenting the M phenotype. The tet(M) gene was the most frequent (86.1%) among Ery-R isolates that were also resistant to tetracycline. Pulsed-field gel electrophoresis (PFGE) analysis after SmaI digestion revealed the occurrence of clonal relationships within groups of strains belonging to serotypes 14, 19A, and 23F. All Ery-R isolates belonging to serotype 14 were susceptible to penicillin and were included in a single clonal group (named Ery(14)-A) related to the England(14-)9 internationally spread clone.

Brazil↗

PubMed2004

Vagococcus carniphilus sp. nov., isolated from ground beef.

Nine enterococcus-like strains were referred to the Streptococcus Laboratory at the Centers for Disease Control and Prevention (CDC) for further identification from the National Antimicrobial Resistance Monitoring System Laboratory at the CDC. The cultures were isolated from ground beef purchased from retail in Oregon in 2000. Conventional biochemical testing and analysis of whole-cell protein electrophoretic profiles distinguished these strains from known species of enterococci and vagococci. Comparative 16S rRNA gene sequencing studies revealed that these strains were most closely related to the species Vagococcus fluvialis. DNA-DNA reassociation studies confirmed that these nine strains represented a new taxon. The relative binding ratio was 87 % or greater at the optimal temperature, and the divergence was less than 1 % for strains hybridized against the isolate designated the type strain. DNA-DNA relatedness was 25 % to V. fluvialis and 9 % or less to the other three species of Vagococcus. DNA-DNA relatedness was 33 % or less to the 25 currently described species of Enterococcus. On the basis of this evidence, it is proposed that these strains be classified as Vagococcus carniphilus sp. nov. The type strain of V. carniphilus is 1843-02T (= ATCC BAA-640T = CCUG 46823T). The clinical significance (if any) of these strains is yet to be determined.

Animals↗

PubMed2004

Emergence of Streptococcus pneumoniae with very-high-level resistance to penicillin.

Penicillin resistance threatens the treatment of pneumococcal infections. We used sentinel hospital surveillance (1978 to 2001) and population-based surveillance (1995 to 2001) in seven states in the Active Bacterial Core surveillance of the Emerging Infections Program Network to document the emergence in the United States of invasive pneumococcal isolates with very-high-level penicillin resistance (MIC > or = 8 microg/ml). Very-high-level penicillin resistance was first detected in 1995 in multiple pneumococcal serotypes in three regions of the United States. The prevalence increased from 0.56% (14 of 2,507) of isolates in 1995 to 0.87% in 2001 (P = 0.03), with peaks in 1996 and 2000 associated with epidemics in Georgia and Maryland. For a majority of the strains the MICs of amoxicillin (91%), cefuroxime (100%), and cefotaxime (68%), were > or =8 microg/ml and all were resistant to at least one other drug class. Pneumonia (50%) and bacteremia (36%) were the most common clinical presentations. Factors associated with very highly resistant infections included residence in Tennessee, age of <5 or > or =65 years, and resistance to at least three drug classes. Hospitalization and case fatality rates were not higher than those of other pneumococcal infection patients; length of hospital stay was longer, controlling for age. Among the strains from 2000 and 2001, 39% were related to Tennessee(23F)-4 and 35% were related to England(14-)9. After the introduction of the pneumococcal conjugate vaccine, the incidence of highly penicillin resistant infections decreased by 50% among children <5 years of age. The emergence, clonality, and association of very-high-level penicillin resistance with multiple drug resistance requires further monitoring and highlights the need for novel agents active against the pneumococcus.

DNA-Cytosine Methylases↗

PubMed2004

Levofloxacin-resistant invasive Streptococcus pneumoniae in the United States: evidence for clonal spread and the impact of conjugate pneumococcal vaccine.

The emergence of fluoroquinolone resistance in sterile-site isolates of Streptococcus pneumoniae is documented in this study characterizing all invasive levofloxacin-resistant (MIC, > or = 8 mg/liter) S. pneumoniae isolates (n = 50) obtained from the Centers for Disease Control and Prevention Active Bacterial Core Surveillance from 1998 to 2002. Resistance among all isolates increased from 0.1% in 1998 to 0.6% in 2001 (P = 0.008) but decreased to 0.4% in 2002, while resistance among vaccine serotypes continued to increase from 0.3% in 1998 to 1.0% in 2002, suggesting that fluoroquinolones continue to exert selective pressure on these vaccine serotypes. Only 22% of resistant isolates were not covered by the conjugate vaccine serogroups. Multilocus sequence typing revealed that 58% of resistant strains were related to five international clones identified by the Pneumococcal Molecular Epidemiology Network, with the Spain(23F)-1 clone being most frequent (16% of all isolates). Thirty-six percent of the isolates were coresistant to penicillin, 44% were coresistant to macrolides, and 28% were multiresistant to penicillin, macrolides, and fluoroquinolones. Fifty percent of the isolates were resistant to any three drug classes. Ninety-four percent of the isolates had multiple mutations in the quinolone resistance-determining regions of the gyrA, gyrB, parC, and parE genes. In 16% of the isolates, there was evidence of an active efflux mechanism. An unusual isolate was found that showed only a single parE mutation and for which the ciprofloxacin MIC was lower (2 mg/liter) than that of levofloxacin (8 mg/liter). Our results suggest that invasive pneumococcal isolates resistant to levofloxacin in the United States show considerable evidence of multiple resistance and of clonal spread.

Anti-Bacterial Agents↗

PubMed2004

Accuracy of phenotypic and genotypic testing for identification of Streptococcus pneumoniae and description of Streptococcus pseudopneumoniae sp. nov.

We have identified an unusual group of viridans group streptococci that resemble Streptococcus pneumoniae. DNA-DNA homology studies suggested that a subset of these isolates represent a novel species that may be included in the S. oralis-S. mitis group of viridans group streptococci. We suggest that this novel species be termed Streptococcus pseudopneumoniae. A combination of phenotypic and genetic reactions allows its identification. S. pseudopneumoniae strains do not have pneumococcal capsules, are resistant to optochin (inhibition zones, less than 14 mm) when they are incubated under an atmosphere of increased CO2 but are susceptible to optochin (inhibition zones, >14 mm) when they are incubated in ambient atmospheres, are not soluble in bile, and are positive by the GenProbe AccuProbe Pneumococcus test. The bile solubility test is more specific than the optochin test for identification of S. pneumoniae. Genetic tests for pneumolysin (ply) and manganese-dependent superoxide dismutase (sodA) and identification tests with a commercial probe, AccuProbe Pneumococcus, do not discriminate between the new species and S. pneumoniae.

Bacterial Typing Techniques↗

PubMed2004

Characterization of three new enterococcal species, Enterococcus sp. nov. CDC PNS-E1, Enterococcus sp. nov. CDC PNS-E2, and Enterococcus sp. nov. CDC PNS-E3, isolated from human clinical specimens.

As a reference laboratory, the Streptococcus Laboratory at the Centers for Disease Control and Prevention (CDC) is frequently asked to confirm the identity of unusual or difficult-to-identify catalase-negative, gram-positive cocci. In order to accomplish the precise identification of these microorganisms, we have systematically applied analysis of whole-cell protein profiles (WCPP) and DNA-DNA reassociation experiments, in conjunction with conventional physiological tests. Using this approach, we recently focused on the characterization of three strains resembling the physiological groups I (strain SS-1730), II (strain SS-1729), and IV (strain SS-1728) of enterococcal species. Two strains were isolated from human blood, and one was isolated from human brain tissue. The results of physiological testing were not consistent enough to allow confident inclusion of the strains in any of the known enterococcal species. Resistance to vancomycin was detected in one of the strains (SS-1729). Analysis of WCPP showed unique profiles for each strain, which were not similar to the profiles of any previously described Enterococcus species. 16S ribosomal DNA (rDNA) sequencing results revealed three new taxa within the genus ENTEROCOCCUS: The results of DNA-DNA relatedness experiments were consistent with the results of WCPP analysis and 16S rDNA sequencing, since the percentages of homology with all 25 known species of Enterococcus were lower than 70%. Overall, the results indicate that these three strains constitute three new species of Enterococcus identified from human clinical sources, including one that harbors the vanA gene. The isolates were provisionally designated Enterococcus sp. nov. CDC Proposed New Species of Enterococcus 1 (CDC PNS-E1), type strain SS-1728(T) (= ATCC BAA-780(T) = CCUG 47860(T)); Enterococcus sp. nov. CDC PNS-E2, type strain SS-1729(T) (= ATCC BAA-781(T) = CCUG 47861(T)); and Enterococcus sp. nov. CDC PNS-E3, type strain SS-1730(T) (= ATCC BAA-782(T) = CCUG 47862(T)).

Centers for Disease Control and Prevention, U.S.↗

PubMed2004

Immunoblot method to detect Streptococcus pneumoniae and identify multiple serotypes from nasopharyngeal secretions.

Conventional culture techniques are limited in the ability to detect multiple Streptococcus pneumoniae serotypes in nasopharyngeal (NP) secretions. We developed an immunoblot (IB) method with monoclonal antibodies (MAbs) to detect S. pneumoniae and to identify serotypes. NP specimens stored in skim milk-tryptone-glucose-glycerol medium were assessed by the IB method and the reference culture method (RM). In the RM, four optochin-sensitive alpha-hemolytic colonies resembling pneumococci were typed by the Quellung reaction. In the IB method, a nitrocellulose membrane blot of surface growth was reacted with a pneumococcal surface adhesion (PsaA) MAb and visualized. Of 47 NP specimens, 32 (68%) were found to be positive and 13 (28%) were found to be negative for pneumococci by both methods; each method alone yielded one positive result. The sensitivity and specificity of the IB method for the detection of pneumococci were 97 and 93%, respectively. To identify serotypes, blots were tested with serotype-specific MAbs (4, 6A, 6B, 9V, 14, 18C, 19F, and 23F). To detect the remaining serotypes, positive serotype-specific replicate blots were compared visually to an original anti-PsaA-positive blot; four unidentified colonies were subcultured and serotyped by the Quellung reaction. Fifty-eight S. pneumoniae-positive NP specimens containing 69 pneumococcal strains (23 serotypes) were tested; 68 (98.6%) of the strains were detected by the IB method, and 66 (95.6%) were detected by the RM. For 11 specimens found to contain two serotypes, both methods detected both serotypes in 7 (63.6%), the IB method alone detected the two serotypes in 3 (27.3%), and the RM alone detected both serotypes in 1 (9%). The IB method identified multiple clones and minor populations of pneumococci in NP secretions. This method is useful for detecting specific serotypes and carriage of multiple serotypes in epidemiologic surveillance and carriage studies.

Antibodies, Bacterial↗