Early onset neonatal sepsis caused by serotype VIII group B streptococci

Late-onset invasive group B Streptococcal infection with serotype VIII in a neonate having congenital biliary atresia

A female newborn was admitted to our department 15 days after birth for insufficient sucking and jaundice. The patient's blood and urine cultures were both positive for group B streptococcal (GBS) infection. A maternal vaginal sample at 35 weeks' gestation was negative for GBS in culture-based microbiologic screening. The patient recovered shortly after receiving systemic antibiotic therapy. On the basis of clinical evidence of white stool and progressive jaundice, we suspected that the newborn had complications related to congenital biliary atresia (CBA); surgery was performed. Isolates from the mother's vaginal sample obtained when the patient was 25 days old, along with neonatal blood, revealed identical patterns (serotype VIII and sequence type 1) of GBS capsular and multilocus sequence typing, suggestive of maternal transmission. Molecular epidemiologic examination may be useful to clarify the transmission route and etiology; culture-based microbiologic screening appears to have limitations for detecting the route of transmission.

Role of pilus proteins in adherence and invasion of Streptococcus agalactiae to the lung and cervical epithelial cells

Streptococcus agalactiae, or group B Streptococcus (GBS), is an important opportunistic pathogen that causes pneumonia, sepsis, and meningitis in neonates and severe diseases in immunocompromised adults. We have performed comparative genomics of prevalent GBS serotypes of Indian origin (i.e. Ia, III, V, and VII). Pilus-proteins were commonly found up-regulated, and their expression was studied by using antiserum for GBS80 (backbone protein of pilus island-I), GBS67 (ancillary protein of PI-2a), and SAN1518 (backbone protein of PI-2b) by whole cell and Western blot analysis. To check the role of pilus proteins in adherence and invasion, an inhibition assay was performed. Comparative immunoblotting experiments revealed that expression of pili proteins does not differ in geographically different selected serotypes, Ia and V, of India and the United States. In the case of A549 cells, we found that GBS VII invasion and adherence was inhibited by pilus protein-specific antiserum SAN1518 significantly (p < 0.001) by 88.5 and 91%, respectively. We found that mutant strains, deficient in the pilus proteins (Δgbs80 and Δsan1518) exhibit a significant decrease in adherence in the case of type Ia, III, and VII. In the case of type VII, we have found a 95% reduction in invasion when Δsan1518 was used with A549 cells. Because the pilus proteins were identified previously as vaccine candidates against GBS serotypes of developed countries, we also found their role in the attachment and invasion of GBS of Indian origin. Thus, the present work supports the idea of making a more effective pilus protein-based vaccine that can be used universally.

Invasive group B streptococcal infections in a tertiary care hospital between 1998 and 2007 in Japan

OBJECTIVE

To clarify clinical and microbiological features of invasive group B Streptococcus (GBS) disease in Japan.

METHODS

This was a retrospective review for the period 1998-2007 of patients across all age groups in Nishi-Kobe Medical Center. Invasive GBS disease was defined as GBS isolation from a normally sterile site or skin/soft tissues.

RESULTS

Six infant and 52 adult cases of invasive infection were identified. Diagnosis was limited to bacteremia and meningitis in infants, but varied widely in adults with skin/soft tissue infections and bacteremia being common. The overall fatality rate was 16%. An approximately 2.8-fold increase was found in the incidence among adult patients from the first to the second 5-year period. The most frequent underlying condition was diabetes, with the majority (18/23) of such patients showing poor control (HbA1c >8.0%). Amputation at the knee, ankle, or toes was performed in six diabetic adults with skin/soft tissue infections. Of the strains serotyped, types Ib and III predominated. All 58 strains were susceptible to penicillin; 2% were resistant to erythromycin and 3% were resistant to clindamycin.

CONCLUSION

This is the first epidemiological report describing invasive GBS disease in Japan. A significant increase in adult patients was noted, and mortality and morbidity remain substantial.

State of the science: neonatal bacterial infection in the early 21st century

Bacterial infections continue to cause significant neonatal morbidity and mortality, especially in small preterm neonates in the neonatal intensive care unit. Maternal and newborn risk factors can be used to prevent newborn infection and initiate early clinical assessments, laboratory diagnostic tests, and antimicrobial agent therapies. Early-onset and late-onset infections have different clinical patterns; however, each must be recognized as soon as possible in order to optimize outcomes. Antibiotics have long been the mainstay of treatment but organism resistance and weak immune system functioning of very premature newborns makes treatment challenging. Research continues on other markers for infection that may lead to more rapid diagnosis. The discovery of new therapies to improve newborn immune system function promises further improvement in outcomes of newborn infection. This article gives an overview of the state of diagnosis and treatment of newborn infection.

Adherence to, invasion by, and cytokine production in response to serotype VIII group B Streptococci

The adherence to and invasion of the human epithelial cell line A549 by group B streptococcus (GBS) serotype VIII strains were compared with those of serotype III strains by a conventional method and the dynamic in vitro attachment and invasion system. Twenty GBS strains, including nine vaginal isolates and one invasive isolate each of serotypes III and VIII, were used in the conventional attachment and invasion assay. Adherence to and invasion of A549 cells by serotype VIII GBS strains were significantly greater (P < 0.0001) than those by serotype III strains for both the invasive strain and vaginal isolates. Cytokine production by A549 cells following stimulation with GBS serotypes III and VIII or their purified capsular polysaccharides (CPS) was measured. Serotype III strains stimulated significantly greater tumor necrosis factor alpha (TNF-alpha) (P < 0.0001) and interleukin-10 (IL-10) (P < 0.05) production than did serotype VIII strains. IL-8 production in response to serotype VIII was significantly higher (P < 0.001) than that in response to serotype III. TNF-alpha, IL-8, and IL-10 production was greater in A549 cells infected with GBS than in the untreated control cells. TNF-alpha production was significantly greater (P < 0.005) after stimulation with purified GBS serotype III CPS than after stimulation with serotype VIII CPS, a result similar to that after stimulation with whole GBS. IL-12 production by A549 cells was observed only in response to infection with GBS serotype III, resulting in the possibility of a greater TH1 response in serotype III GBS. These results suggest differences in immune responses to infection with GBS serotypes III and VIII.

Neonatal bacterial sepsis

Neonatal bacterial infection is a significant cause of morbidity and mortality despite improved survival of premature newborns, better understanding of the pathophysiology of sepsis, advances in supportive care, and more potent antibacterial agents. Early recognition and implementation of appropriate therapy offers the best outcome, and careful assessment of the newborn is essential. Current methods to detect signs of sepsis and to identify the causative microorganism are not 100% sensitive and precise. Continued research on other indicators may yield better diagnostic methods and therapy in the future. Research is necessary to identify the most sensitive markers for diagnosis of sepsis and methods of immune enhancement that are safe and effective.

Late antenatal carriage of group B Streptococcus by New Zealand women

OBJECTIVES

To determine in New Zealand women the prevalence of group B Streptococcus (GBS) carriage late in pregnancy and to identify GBS colonisation risk factors, antibiotic susceptibility and serotype distribution.

DESIGN

Prospective, observational study.

SETTING

Community and hospital antenatal clinics in Wellington and Auckland during 1998-1999.

SAMPLE

Convenience sample of 240 women between 35-37 weeks gestation.

METHODS

Sociodemographic data, obstetric details and anogenital swabs were collected from each subject. Swabs were inoculated into selective media. GBS isolates underwent serotyping and antibiotic susceptibility testing.

RESULTS

Two hundred and forty women (9% Maori, 11% Pacific) aged 15-41 years were recruited. Fifty-two (22%; 95% CI 17, 27) were colonised by GBS. Carriage was independently associated with younger age (59% < or = 30 years; adjusted OR 3.25; 95% CI 1.53, 6.95) and least social deprivation (57% NZ Dep 96 score +/- 3; adjusted OR 1.22; 95% CI 1.06,1.39). All GBS isolates were penicillin-susceptible, but resistance to clindamycin (15%) and erythromycin (7.5%) was detected and associated with serotype V strains. Predominant serotypes were: III (29%), Ia (21%), Ib (20%) and V (20%).

CONCLUSIONS

Approximately 20% of New Zealand women carry GBS late in pregnancy, with young age a major risk factor. Increased risk in the socially advantaged, development of resistance to erythromycin and clindamycin, and emergence of new GBS serotypes are findings with important implications for prevention strategies requiring further confirmation.