Specimen storage in transport medium and detection of group B streptococci by culture

Bacteriology & bivalves: Assessing diagnostic tools for geographically remote bivalve populations

Two sampling approaches for the growth of common or dominant bacteria from bivalve haemolymph were compared: (1) samples processed in the field immediately after collection (field samples), and (2) samples processed in the laboratory at least 24 h after collection (laboratory samples). The sampling approaches were compared on 210 marine bivalve molluscs Paphies subtriangulata and P. australis from two shallow intertidal sites in North Island New Zealand. The approaches were evaluated for the amount of bacterial growth, type of growth, and diversity of growth. Differences in amount and type of growth between the two sampling approaches were observed. Samples processed in the field from P. subtriangulata had significantly more bacterial growth, and a higher diversity of bacteria, including more common or dominant bacterial species. Laboratory samples had a higher proportion of samples with no growth, however common or dominant bacteria were still isolated from these samples. For P. australis, field samples more often had no bacterial growth and laboratory samples had a significantly higher number of common or dominant growth present. Field samples did however contain a higher diversity of bacteria. By conducting bacteriology on bivalves in either the field or the laboratory only, there may be limitations to determining the significance of a bacterial agent isolated. Sampling of both field and laboratory samples should be carried out where possible to optimise detection of important bacteria.

Determination of antimicrobial effect of protamine by transmission electron microscopy and SDS PAGE on Pseudomonas aeruginosa isolates from diabetic foot infection

Objective(s):

Diabetic foot infection is one of the major complications of diabetes leading to lower limb amputations. Isolation and identification of bacteria causing diabetic foot infection, determination of antibiotic resistance, antimicrobial potential of protamine by electron microscopy and SDS-PAGE analysis, arethe aims of this study.

Materials and Methods:

285 pus samples from diabetic foot infection patients were collected from different hospitals of Karachi and Capital Health Hospital, Halifax, Canada. Clinical history of each patient was recorded. Bacterial isolates were cultured on appropriate media; identification was done by morphology, cultural and biochemical tests. Effect of protamine against multi drug resistant strains of Pseudomona aeruginosa was checked by minimum inhibitory concentration in 96 well micro-titer plates. The isolates were grown in bactericidal concentration of protamine on plates to isolate mutants. Effect of protamine on protein expression was checked by SDS- PAGE and ultra-structural morphological changes by transmission electron microscopy.

Results:

Results indicated prevalence of foot infection as 92% in diabetic patients. Major bacterial isolates were Staphylococcus aureus 65 (23%), P. aeruginosa 80 (28.1%), Klebsiella spp. 37 (13%), Proteus mirabilis 79 (27.7%), and Escherichia coli 24 (12%). These isolates were highly resistant to different antibiotics. MIC value of protamine was 500 µg/ml against P. aeruginosa. SDS-PAGE analysis revealed that protamine can suppress expression of various virulence proteins and electron micrographs indicated condensation of cytoplasm and accumulation of protamine in cytoplasm without damaging the cell membrane.

Conclusion:

P. aeruginosa and S. aureus were the major isolates expressing multi-drug resistance and protamine sulfate represented good antimicrobial potential.

Vaccines for maternal immunization against Group B Streptococcus disease: WHO perspectives on case ascertainment and case definitions

Group B Streptococcus (GBS) is an important cause of disease in young infants, stillbirths, pregnant and post-partum women. GBS vaccines for maternal immunization are in development aiming to reduce this burden. Standardisation of case definitions and ascertainment methodologies for GBS disease is needed to support future trials of maternal GBS vaccines. Considerations presented here may also serve to promote consistency in observational studies and surveillance, to better establish disease burden. The World Health Organization convened a working group to provide consensus guidance for case ascertainment and case definitions of GBS disease in stillbirths, infants, pregnant and post-partum women, with feedback sought from external stakeholders. In intervention studies, case capture and case ascertainment for GBS disease should be based on antenatal recruitment of women, with active follow-up, systematic clinical assessment, standardised sampling strategies and optimised laboratory methods. Confirmed cases of invasive GBS disease in stillbirths or infants should be included in a primary composite endpoint for vaccine efficacy studies, with GBS cultured from a usually sterile body site (may be post-mortem). For additional endpoints, or observational studies, confirmed cases of GBS sepsis in pregnant and post-partum women should be assessed. Culture independent diagnostic tests (CIDTs) may detect additional presumed cases, however, the use of these diagnostics needs further evaluation. Efficacy of vaccination against maternal and neonatal GBS colonisation, and maternal GBS urinary tract infection could be included as additional, separate, endpoints and/or in observational studies. Whilst the focus here is on specific GBS disease outcomes, intervention studies also present an opportunity to establish the contribution of GBS across adverse perinatal outcomes, including all-cause stillbirth, preterm birth and neonatal encephalopathy.

Reliable Detection of Group B Streptococcus in the Clinical Laboratory

Group B streptococcus (GBS) is a leading cause of invasive neonatal infections and a significant pathogen in immunocompromised adults. Screening to detect GBS colonization in pregnant women determines the need for antibiotic prophylaxis in that pregnancy. Efficient determination of the GBS colonization status of pregnant women is crucial. Methods that maximize the probability of GBS recovery are needed. The availability of technologies such as matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), molecular techniques, and chromogenic culture media, including Granada-type media, have changed the scenario for GBS detection and identification. This review presents and evaluates novel diagnostic tools, as well as classic identification techniques, for GBS species determination.

Group B Streptococcus and perinatal mortality

The World Health Organization estimates that every year, one million neonatal deaths occur because of neonatal infection. Furthermore, an equal number of stillbirths are thought to be caused by infections. Here we discuss the role of Streptococcus agalactiae (group B Streptococcus, GBS) in neonatal disease and stillbirth.

Group B streptococcus infections in neonates admitted to a German NICU: Emphasis on screening and adherence to pre-analytical recommendations

BACKGROUND

Infections by group B streptococci (GBS), e.g. Streptococcus agalactiae, presenting as early-onset disease (EOD) or late-onset disease (LOD), are leading causes of severe infections in newborn and premature patients. Although screening and intra partum antibiotic prophylaxis are frequently performed, vertically transmitted GBS remain a challenge for pediatrics.

AIMS

In order to prevent or reduce potential life-threatening events, this study retrospectively investigated epidemiological, microbiological and clinical aspects of infants admitted to the Division of Neonatology at the Department of Pediatrics at the University Hospital Frankfurt, Germany (UHF).

STUDY DESIGN AND SUBJECTS

Between January 2010 and January 2016, perinatal GBS screening status, clinical presentation of EOD or LOD and therapeutic management of neonates admitted to UHF were retrospective analysed. Infants tested positive for GBS within their first three months of life were included; patient data were obtained from the chart report. Severity of neonatal disease was analysed by using the NEOMOD and CRIB score.

RESULTS

108 GBS infected infants born to 105 mothers were observed. N=101 of them (93.5%) presented with EOD, whereof n=9 (10%) primarily presented with pneumonia or pneumothorax. In 82 (78%) mothers of infected infants GBS status was unknown prior to hospitalization of the neonate. 3/108 (2.8%) infants died from GBS septicemia.

CONCLUSION

Avoidance of GBS transmission sub partu is the key issue in preventing neonatal GBS infection and should be the focus of preventive strategies. Our results highlight the impact of perinatal screening.

Isolation and anti-microbial susceptibility pattern of group B Streptococcus among pregnant women attending antenatal clinics in Ayder Referral Hospital and Mekelle Health Center, Mekelle, Northern Ethiopia

Background

Vaginal colonization with group B Streptococcus (GBS) is the predominant risk factor for the development of invasive neonatal GBS diseases and puts newborns at increased risk for morbidity and mortality. This study is aimed to determine the colonization rate and antimicrobial susceptibility pattern of group B Streptococcus among pregnant women.

Methods

Hospital based cross-sectional study was conducted from August to December 2014 at selected health facilities. A total of 139 antenatal clinics attendees, proportionally allocated, were recruited consecutively. Socio-demographic and clinical factors were collected using a structured questionnaire. Vaginal swabs were collected and cultured on Todd Hewitt broth and in 5 % sheep blood agar. Antimicrobial susceptibility test was done using Kirby-Bauer disk diffusion test. Statistical analysis was performed using Pearson’s Chi square test.

Results

Among the 139, 19 (13.7 %) were positive for GBS. All the GBS isolates were susceptible (100 %) to penicillin G, vancomycin, ampicillin, erythromycin and gentamicin. Two of the GBS isolates showed multidrug resistance against norfloxacin and ciprofloxacin. No statistically significant difference was observed for GBS colonization with any independent variables.

Conclusion

Vaginal colonization of GBS for the present study put emphasis on further investigation and accomplishment of routine GBS screening practices. The recovery of resistant strains to antimicrobial agents recommended in cases of penicillin allergic mothers indicates the importance of susceptibility test.

Group B streptococcal epidemiology and vaccine needs in developed countries

Development of a group B streptococcal vaccine (GBS) vaccine is the most promising approach for the prevention of GBS infections in babies, given the potential adverse effects of intrapartum antibiotic prophylaxis as well as the need for effective prevention of both adult and late perinatal disease. There are numerous prevention strategies at this time but none are 100% effective in the eradication of neonatal early onset GBS disease and there are no preventative strategies for late onset disease. The need for a GBS vaccine is therefore, of utmost importance. Efforts applying genomics to GBS vaccine development have led to the identification of novel vaccine candidates. The publication of GBS whole genomes coupled with new technologies including multigenome screening and bioinformatics has also allowed researchers to overcome the serotype limitation of earlier vaccine preparations in the search of a universal effective vaccine against GBS. This review brings together the key arguments concerning the potential need of a GBS vaccine in developed countries and describes the current status with GBS epidemiology and microbiology in these countries.

[Prevention of Neonatal Group B Sreptococcal Infection. Spanish Recommendations. Update 2012. SEIMC/SEGO/SEN/SEQ/SEMFYC Consensus Document]

Group B streptococci (GBS) remain the most common cause of early onset neonatal sepsis. In 2003 the Spanish Societies of Obstetrics and Gynaecology, Neonatology, Infectious Diseases and Clinical Microbiology, Chemotherapy, and Family and Community Medicine published updated recommendations for the prevention of early onset neonatal GBS infection. It was recommended to study all pregnant women at 35-37 weeks gestation to determine whether they were colonised by GBS, and to administer intrapartum antibiotic prophylaxis (IAP) to all colonised women. There has been a significant reduction in neonatal GBS infection in Spain following the widespread application of IAP. Today most cases of early onset GBS neonatal infection are due to false negative results in detecting GBS, to the lack of communication between laboratories and obstetric units, and to failures in implementing the prevention protocol. In 2010, new recommendations were published by the CDC, and this fact, together with the new knowledge and experience available, has led to the publishing of these new recommendations. The main changes in these revised recommendations include: microbiological methods to identify pregnant GBS carriers and for testing GBS antibiotic sensitivity, and the antibiotics used for IAP are updated; The significance of the presence of GBS in urine, including criteria for the diagnosis of UTI and asymptomatic bacteriuria in pregnancy are clarified; IAP in preterm labour and premature rupture of membranes, and the management of the newborn in relation to GBS carrier status of the mother are also revised. These recommendations are only addressed to the prevention of GBS early neonatal infection, are not effective against late neonatal infection.

Evaluation of optimal storage temperature, time, and transport medium for detection of group B Streptococcus in StrepB carrot broth

The performances of the ESwab and Amies transport media were evaluated for optimal survival of group B streptococcus (GBS) in StrepB carrot broth. ESwab was superior to Amies at all temperatures evaluated but was optimal at 21°C and 24°C, whereas recovery in Amies was significantly decreased at these temperatures.

In vitro evaluation of the performance of Granada selective enrichment broth for the detection of group B streptococcal colonization

A broth for the screening of group B streptococcal (GBS) carriage during pregnancy is about to be introduced. Simulating conditions in everyday practice, we have compared the sensitivity of this Granada tube broth (GT) with that of classical Amies transport medium (AT) in vitro. A total of 1,485 GT and 1,485 AT were tested with 33 well-characterized GBS strains in three different concentrations, five different incubation times, and three different temperatures. After initial incubation at room temperature (RT) or 4°C, GT were placed at 37°C. GT were scored for the presence of orange pigment. GT and AT were subcultured on blood agar (BA). Pigment was observed in 98% of GT incubated at 37°C. GBS could be cultured in 91%, 73%, and 55% of GT incubated at 37°C, RT, or 4°C, respectively. For AT, these percentages were only 20% at 37°C, 52% at RT, and 59% at 4°C. When GT initially incubated at RT or 4°C were subsequently incubated at 37°C, the sensitivity improved significantly. We conclude that GT is a more sensitive GBS transport and culture medium than the conventional method, especially for low inocula and prolonged transport/incubation times. GT does not exclude the presence of GBS, and should always be incubated at 37°C and subcultured on solid agar for optimal sensitivity.

Quantitative survival of aerobic and anaerobic microorganisms in Port-A-Cul and Copan transport systems

Transport media should preserve the viability and stability of microorganisms in clinical specimens. In this study, the Port-A-Cul transport system and the Copan transport system without charcoal, both designed to preserve anaerobes, were evaluated. Dacron swabs were inoculated with two combinations of facultative and anaerobic organisms typically found in vaginal swab samples. Combination I contained Candida albicans, Escherichia coli, Enterococcus spp., group B streptococci, Lactobacillus crispatus, and Staphylococcus aureus. Combination II contained Lactobacillus iners, Peptoniphilus asaccharolyticus, Mycoplasma hominis, Prevotella bivia, Prevotella corporis, Porphyromonas asaccharolytica, Mobiluncus curtisii, Peptostreptococcus anaerobius, and Gardnerella vaginalis. Duplicate swabs were placed into the two transporters and held for 24, 48, 72, and 96 h at 4 and 24 degrees C. Both transporters maintained the viability of organisms better at 4 degrees C than at 24 degrees C. Prevotella bivia and Prevotella corporis had a loss of viability in both transporters at both temperatures. However, at 24 degrees C, there was a significantly greater loss of viability for Mycoplasma hominis, Prevotella bivia, Prevotella corporis, and Peptoniphilus asaccharolyticus when the organisms were stored in Copan transport medium than when they were stored in Port-A-Cul transport medium for 96 h (P < 0.002). Some organisms proliferated in the transport media, but when transporters were held at 24 degrees C for 96 h, a significantly greater increase in the concentrations of group B streptococci and Candida albicans, Escherichia coli, and Enterococcus spp. organisms in Copan medium than in Port-A-Cul medium was observed (P < 0.002). At room temperature, the Port-A-Cul system is superior to the Copan system with respect to the preservation of fastidious microorganisms and the prevention of the proliferation of facultative organisms.

Sensitivities of antigen detection and PCR assays greatly increased compared to that of the standard culture method for screening for group B streptococcus carriage in pregnant women

Group B streptococcus (GBS) is a major cause of serious infections in neonates. The 2002 revised guidelines of the Centers for Disease Control and Prevention (CDC) for the prevention of perinatal GBS disease recommend that all pregnant women be screened for GBS carriage at between 35 and 37 weeks of gestation and that intrapartum antibiotic prophylaxis be given to carriers. We studied the performances of four different GBS detection assays in the context of antenatal screening. Between May and August 2004, the 605 vaginorectal swab specimens received at our bacteriology laboratory for GBS antenatal detection were tested by the four assays. The standard culture method was done according to the CDC recommendations. The three experimental assays performed with the growth from the selective enrichment (LIM) broth (Todd-Hewitt broth with 15 mug/ml nalidixic acid and 10 mug/ml colistin) after overnight incubation were a GBS antigen detection assay (PathoDx) and two PCR assays (for cfb and scpB). The most accurate assay was the scpB PCR (sensitivity, 99.6%; specificity, 100%), followed by the cfb PCR (sensitivity, 75.3%; specificity, 100%), GBS antigen detection (sensitivity, 57.3%; specificity, 99.5%), and standard culture (sensitivity, 42.3%; specificity, 100%). The GBS antigen detection assay was found to be more sensitive than the standard culture method, and moreover, the assay has a low cost and is easy to perform in all obstetrical centers which have access to the most basic of diagnostic microbiology services. We believe that antigen detection on incubated LIM broth should replace the standard culture method for screening for GBS carriage at 35 to 37 weeks of gestation. The impact of the greater sensitivities of PCR assays on the diminution of neonatal GBS infections remains to be demonstrated.