Fatal infection in neonates of 26 weeks' gestation due to Streptococcus milleri: report of two cases

Anovaginal Colonization by Group B Streptococcus and Streptococcus anginosus among Pregnant Women in Brazil and Its Association with Clinical Features

Streptococcus agalactiae (Group B Streptococcus; GBS) is a leading cause of neonatal invasive disease worldwide. GBS can colonize the human gastrointestinal and genitourinary tracts, and the anovaginal colonization of pregnant women is the main source for neonatal infection. Streptococcus anginosus, in turn, can colonize the human upper respiratory, gastrointestinal, and genitourinary tracts but has rarely been observed causing disease. However, in the last years, S. anginosus has been increasingly associated with human infections, mainly in the bloodstream and gastrointestinal and genitourinary tracts. Although anovaginal screening for GBS is common during pregnancy, data regarding the anovaginal colonization of pregnant women by S. anginosus are still scarce. Here, we show that during the assessment of anovaginal GBS colonization rates among pregnant women living in Rio de Janeiro, Brazil, S. anginosus was also commonly detected, and S. anginosus isolates presented a similar colony morphology and color pattern to GBS in chromogenic media. GBS was detected in 48 (12%) while S. anginosus was detected in 17 (4.3%) of the 399 anovaginal samples analyzed. The use of antibiotics during pregnancy and history of urinary tract infections and sexually transmitted infections were associated with the presence of S. anginosus. In turn, previous preterm birth was associated with the presence of GBS (p < 0.05). The correlation of GBS and S. anginosus with relevant clinical features of pregnant women in Rio de Janeiro, Brazil, highlights the need for the further investigation of these important bacteria in relation to this special population.

The Vaginal Microbiota Composition and Genital Infections during and after Pregnancy among Women in Pemba Island, Tanzania

We investigated the vaginal microbiota (VMB) composition, prevalence of genital pathogens and their association among pregnant and post-delivery women in Pemba Island, Tanzania. Vaginal swabs were collected from 90 women, at two time points during pregnancy (<20 weeks of gestational age [GA] and ≥20 weeks GA) and once after delivery, when possible. IS-pro assay was used for VMB characterization. Chlamydia trachomatis (CT), Neisseria gonorrhea (NG), Trichomonas vaginalis (TV), Mycoplasma genitalium (MG) and human papillomavirus (HPV) were detected by qPCRs. VMB were mostly Lactobacillus dominant during pregnancy and non-Lactobacillus dominant post-delivery. A significant decrease in VMB richness was observed during pregnancy among paired and unpaired samples. Shannon diversity was significantly lower during pregnancy than post-delivery among unpaired samples. Klebsiella species and Streptococcus anginosus were the most commonly identified pathobionts at all timepoints. A high abundance of pathobionts was mostly seen in women with non-Lactobacillus dominant VMB. At ≥20 weeks GA timepoint during pregnancy, 63.0% of the women carrying one or more genital pathogen (either HPV, CT, TV, or MG) had L. iners dominant VMB. NG was not detected pre-delivery. This study contributes evidence on VMB composition, its changes during pregnancy and post-delivery, and their association with pathobionts and genital pathogens.

Seven-year review of bacteremia caused by Streptococcus milleri and other viridans streptococci

The Streptococcus milleri group is associated with a spectrum of serious suppurative infections that have not been well defined. The purposes of this study were to ascertain the clinical significance of Streptococcus milleri bacteremia and to determine the epidemiological, clinical, and microbiological features of these infections compared to those caused by other viridans streptococci. All cases of streptococcal bacteremia observed in a Spanish hospital in the period from January 1988 to December 1994 were reviewed. Of 137 cases of Streptococcus milleri infection, 33 (24%) were documented cases of bacteremia. Twenty-four patients were men (mean age 57.8 +/- 17.4 years). The majority of infections were abdominal in origin (20/33), the most frequent diagnoses being cholangitis/cholecystitis (18%) and appendicitis (12%). The origin of infection could not be established in three cases. Nine cases of bacteremia (27%) were polymicrobial. Six patients (18%) had septic shock; in four the infection was polymicrobial, and in two the infection was of abdominal origin. Eighteen of the 33 patients (54%) required surgery. Five patients died. All 33 Streptococcus milleri isolates were susceptible to penicillin. Twenty-two cases of bacteremia caused by other viridans streptococci were observed during the same period. There were no statistically significant differences between the two groups in terms of age, sex, mortality, rate of polymicrobial infection, rate of nosocomial acquisition of bacteremia, or the occurrence of shock. An abdominal origin of infection was more frequent in Streptococcus milleri bacteremia (p = 0.0001); a cardiovascular origin was more frequent in the viridans group (p = 0.01), as was a diagnosis of endocarditis (p = 0.004). Four patients with viridans streptococci bacteremia required surgery versus 18 patients with Streptococcus milleri bacteremia (p = 0.01). Viridans streptococci were notably less susceptible to penicillin (89%), clindamycin (79%), and erythromycin (79%).

Neonatal infection with Streptococcus milleri

Streptococcus milleri is a known commensal of the female genitourinary tract, but its pathogenicity in neonates has been reported in only a few cases. During a period of one year in an obstetrical unit, Streptococcus milleri was isolated from nine neonates and from one foetus after a spontaneous abortion. In seven of the nine newborns, neonatal infection was assessed and Streptococcus milleri was the lone pathogen involved, associated with positive blood or vaginal cultures in four mothers. Because Streptococcus milleri requires special conditions for identification, it is probably underestimated as a cause of neonatal infection and septic abortion.

Bacteremia due to viridans streptococci in neutropenic patients: a review

Viridans streptococci have long been considered, with the exception of the ability to cause endocarditis, as minor pathogenic agents. More recently, however, these bacteria have become a major concern in neutropenic patients undergoing a chemotherapeutic treatment. In this high-risk population, they can be responsible for up to 39% of bacteremia cases and are the most frequent cause of this type of infection. The most frequently isolated species in blood cultures are Streptococcus mitis and Streptococcus sanguis II. Viridans streptococcus bacteremia can be accompanied by serious complications, like adult respiratory distress syndrome (ARDS) (3% to 33%), shock (7% to 18%) or endocarditis (7% to 8%). Mortality rates range from 6% to 30%. Case-control studies have identified the following risk factors: severe neutropenia (< 100 neutrophils/mm3), prophylactic antibiotic treatments with quinolone or co-trimoxazole, absence of intravenous antibiotics at the time of bacteremia, high doses of cytosine arabinoside, oropharyngeal mucositis, and heavy colonization by viridans streptococci. The introduction of penicillin in prophylactic antibiotic treatments has reduced the incidence of these infections, but the long-term use of penicillin could be compromised by the emergence of resistant strains.

Fulminant septicaemia due to Streptococcus milleri infection in a previously healthy adult

A 59-year-old previously healthy female developed purulent pharyngitis leading rapidly to neck cellulitis, septicaemic shock and fatal cardiac arrest despite appropriate antibiotic therapy. Streptococcus milleri was isolated from a submandibular abscess, cellulitic neck tissue and blood cultures. Fulminant septicaemia due to this group of organisms is relatively uncommon and usually occurs in the immunocompromised or otherwise chronically unwell.

Streptococcus milleri group: renewed interest in an elusive pathogen

The following review examines the bacteriological characteristics, epidemiology, pathogenicity and antimicrobial susceptibility of the "Streptococcus milleri group". "Streptococcus milleri group" is a term for a large group of streptococci which includes Streptococcus intermedius, Streptococcus constellatus and Streptococcus anginosus. Usually considered commensals, these organisms are often associated with various pyogenic infections including cardiac, abdominal, skin and central nervous system infections. Organisms of the "Streptococcus milleri group" are often unrecognized pathogens due to the lack of uniformity in classifications and difficulties in microbiological identification. Penicillin G, cephalosporins, clindamycin and vancomycin all possess activity against these streptococci. Use of agents with poor activity may promote infections with "Streptococcus milleri group" and allow it to exhibit its pathogenicity. An understanding of these organisms may aid in their recognition and proper treatment.

Clinical and bacterial features of infections caused by Streptococcus milleri

The clinical and bacteriological features of 51 infections due to Streptococcus milleri observed in 43 patients over a 2-year period were reviewed. Clinical syndromes included bacteremia in 6 cases, endocarditis in 4 cases, cellulitis and subcutaneous abscesses in 8 cases, pleural empyema in 8 cases, brain abscesses in 5 cases, abdominal infections in 5 cases, and other miscellaneous infections in 15 cases. An underlying condition was associated with infection in 33/43 patients (77%). S. milleri was the only pathogen isolated in 19 patients (44%). All strains of S. milleri were susceptible to penicillin. Surgery was combined with antimicrobial therapy in 27 (63%) patients. Nine patients died during hospitalization, and death was directly related to S. milleri infection in 4 patients (9%). These results confirm that S. milleri frequently causes serious suppurative infections and that species identification is a clinically useful procedure.

Classification and identification of the viridans streptococci

This review traces the history of the human, nonhemolytic, or viridans, streptococci and describes improvements in their taxonomy wrought by study of their biochemical profiles and analysis of their nucleic acids. The goal was to define species on the basis of genetic relationships and to describe these species by their phenotypic characteristics so that they can be easily identified. This method has resulted in the division of some species. Streptococcus mutans has been divided into four species, two of which are common in humans. Three more mutans group species are indigenous to animals. Conversely, S. constellatus, S. intermedius, and "S. milleri" have been combined under S. anginosus. S. mitis (or "S. mitior") can be well-defined and includes S. sanguis II. There is genetic heterogeneity within S. sanguis, but the species is usually easy to identify. There is also some heterogeneity in S. bovis, but most human isolates are genetically related. Discussions of the taxonomy of these species are accompanied by descriptions of the characteristics by which these streptococci can be identified. Among these species are potential pathogens which should be suspected in cases of endocarditis and purulent infections of liver, brain, and other tissues.

Association of viridans group streptococci from pregnant women with bacterial vaginosis and upper genital tract infection

The prevalence and role of viridans group streptococci in the female genital tract have not been well described. In this study of 482 pregnant women, 147 (30%) were culture positive for viridans group streptococci. Of 392 women with predominant Lactobacillus morphotypes by Gram stain (normal), 110 (28%) were colonized with viridans group streptococci, compared with 37 (41%) of 90 women with bacterial vaginosis (BV) (P = 0.02). To determine whether any species were associated with BV, 177 consecutively isolated viridans group streptococci from the vagina were identified to the species level by using the Facklam scheme. The most frequently isolated species from the vagina was Streptococcus intermedius (13%), followed by Streptococcus acidominimus (6%), Streptococcus constellatus (5%), Streptococcus sanguis II (4%), Streptococcus mitis (2%), Streptococcus salivarius (2%), Streptococcus morbillorum (2%), Streptococcus sanguis I (1%), Streptococcus mutans (0.2%), and Streptococcus uberis (0.2%) with an average of 1.2 species per woman. The distribution of the species among women with BV compared with normal women was not significantly different, with the exception of two species which were associated with BV: S. acidominimus (18% versus 3%, P less than 0.001) and S. morbillorum (6% versus 0.7%, P = 0.005). Amniotic fluid and placenta cultures yielded 54 isolates: S. sanguis II (13 isolates), S. acidominimus (9 isolates), S. intermedius (10 isolates), S. constellatus (3 isolates), S. mitis (4 isolates), S. sanguis I (4 isolates), S. morbillorum (5 isolates), S. mutans (2 isolates), S. uberis (1 isolate), mannitol-positive S. intermedius (1 isolate), and 2 isolates which were not classified. The distribution of species isolated from the upper genital tract was not a reflection of the distribution in the lower genital tract. Dextran-producing species of viridans group streptococci may have a greater pathogenic potential in the placenta than the non-dextran-producing species.

Streptococcus anginosus ("Streptococcus milleri"): the unrecognized pathogen

"Streptococcus milleri" is an unofficial name that has been applied to a group of streptococci which, although basically similar, show various hemolytic, serological, and physiological characteristics. The species name Streptococcus anginosus has recently been recognized as the approved name for these organisms. Streptococci known as "S. milleri" have been implicated as etiologic agents in a variety of serious purulent infections, but because of their heterogeneous characteristics, these organisms may be unrecognized or misidentified by clinical laboratorians. This review describes the bacteriological aspects of organisms known as "S. milleri," their clinical significance, and the problems encountered with their identification in the clinical laboratory.

Hydrolytic enzymes of "Streptococcus milleri"

Seventy-two isolates classified as "Streptococcus milleri" were examined for the presence of various hydrolytic enzymes. While no protein or lipid-degrading activities were demonstrated, some isolates showed DNase and mucopolysaccharide-degrading activities. Beta-hemolytic isolates were more likely to produce these enzymes than were nonhemolytic strains. Isolates of one "S. milleri" biotype (mannitol fermentation positive) were uniformly devoid of all enzyme activities tested.