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Bacteria
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The LPS which is oriented to the outside of the cell is in contact with the environment. The major surface antigen of all Gram-negative bacteria is the O-antigen, which is a side chain that is attached to the outermost core polysaccharide component of LPS. The core polysaccharide, in turn, is attached to the lipid A component of LPS. The lipid A component is embedded in the phospholipid bilayer of the outer membrane (Figure 15.3). Differences in the O-antigen determine the bacterial serotype.
Review on Imaging Features for COVID-19
Published in S. Prabha, P. Karthikeyan, K. Kamalanand, N. Selvaganesan, Computational Modelling and Imaging for SARS-CoV-2 and COVID-19, 2021
Coronavirus has spherical/pleomorphic, covered, single-stranded, and enveloped RNA with club-modelled glycoprotein. It has subtypes. The subtypes of coronaviruses are alpha (α), beta (β), gamma (γ) and delta (δ). Each subtype has numerous serotypes. Humans are affected by some subtypes; others affect pigs, cats, birds, dogs and mice. Initially, this virus was treated as a non-fatal, simple virus in 2002. Afterwards, it started spreading to various countries, namely, America, Singapore, Hong Kong, Taiwan, Thailand and Vietnam. In 2003, more than 1,000 patients were affected by SARS-Cov; it was called the black year of the microbiologist. In 2004, WHO announced a “state of emergency” for disease control and prevention. Several infected patients’ deaths were reported by Saudi Arabia in 2012. Afterwards, COVID-19 was identified and emerged from Wuhan city (Kumar, 2020).
Other viral infections
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
The true incidences of disease due to enteroviruses are not known and those infections are not reportable. It is thought that between 50% and 80% of infections are asymptomatic. Infections occur throughout the year and are most prevalent from June to October in temperate climates (39,40). Serotypes vary by region or year. The usual route of transmission is by either respiratory droplets or the gastrointestinal route.
Group B Streptococcus colonisation and their antimicrobial susceptibility among pregnant women attending antenatal clinics in tertiary care hospitals in the Western Province of Sri Lanka
Published in Journal of Obstetrics and Gynaecology, 2021
G. N. Dilrukshi, J. Kottahachchi, D. M. B. T. Dissanayake, R. P. Pathiraja, J. Karunasingha, M. K. A. Sampath, U. A. Vidanage, S. S. N. Fernando
Further, the low prevalence seen in South East Asia and the high rates seen in this study and in Europe, America and Africa could be due to the different colonising serotypes. Of the 10 GBS serotypes, some serotypes (especially serotype111) are associated with greater virulence and thereby a higher propensity to invasive disease. Serotype 111 was found less frequently in South East Asian region (Russell et al. 2017). Knowledge of serotype distribution in Sri Lanka is sparse and is an urgent necessity. Since the colonising rate is higher than that of the region, a study on the serotypes would enable to assess the risk of invasive disease in this population of pregnant women from Sri Lanka. Serotyping of the isolates though essential was not carried out in this study and was envisaged in the future and is a limitation currently.
Residual colonization by vaccine serotypes in rural South Africa four years following initiation of pneumococcal conjugate vaccine immunization
Published in Expert Review of Vaccines, 2020
Shabir A. Madhi, Susan A. Nzenze, Marta C. Nunes, Lilian Chinyanganya, Nadia Van Niekerk, Kathleen Kahn, Rhine Twine, Linda De Gouveia, Anne Von Gottberg, Tinevimbo Shiri
The sample collection and laboratory testing methods for the culture of bacteria, including Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus, were as previously reported [13,15]. Briefly, nasopharyngeal swabs were performed in all subjects using an aluminum shafted, Dacron swab (MW and E, Medical Wire and Equipment Co. Ltd., Corsham, Wiltshire, England), in addition to which an oropharyngeal swab was collected from those older than 12y. Samples were processed at the Center for Respiratory Diseases and Meningitis (CRDM) at the National Institute for Communicable Diseases, South Africa, by routine microbiological methodologies. Serotyping was undertaken by the Quellung method using factor and serotype-specific antisera (Statens Serum Institute, Copenhagen, Denmark). Presumptive pneumococcal presenting no phenotypically detectable capsule were categorized as non-typeable, once pneumococcal identification was confirmed with lytA PCR. Where >1 distinct morphological colony type was present, each colony was serotyped. Serotypes 6A, 6B, 6C, and 6D were distinguished only using the relevant antisera and without any additional molecular typing.
Ten years of experience with the pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (Synflorix) in children
Published in Expert Review of Vaccines, 2020
Nicolas Lecrenier, Alen Marijam, Jan Olbrecht, Lamine Soumahoro, Javier Nieto Guevara, Bruce Mungall
Most of the remaining IPD burden in vaccinated populations is caused by serotypes not included in the current PCVs [128–130]. This is in part due to serotype replacement, a phenomenon where non-vaccine serotypes (typically with a low prevalence before PCV introduction) become more prevalent by replacing the types that are covered by PCVs [128–131]. To address this, several new-generation higher-valency PCVs are being developed (e.g., 15-valent PCV [132–134] and 20-valent PCV [ClinicalTrials.gov: NCT03760146, NCT03835975, NCT03828617]). Given the strong direct and herd effects from existing pediatric programs, the incremental benefit of these new-generation PCVs in both children and adults may be interesting from a public health viewpoint, but price premium will need to be limited to meet cost-effectiveness expectations. In addition, it is not known if and to what extent these new-generation vaccines will cause serotype replacement.