Diphtheria: It is still prevalent!!!

Neutralizing anti-diphtheria toxin scFv produced by phage display

BACKGROUND

Diphtheria can be prevented by vaccination, but some epidemics occur in several places, and diphtheria's threat is considerable. Administration of diphtheria antitoxin (DAT) produced from hyperimmunized animals is the most common treatment. Recombinant human antibody fragments such as single-chain variable fragments (scFv) produced by phage display library may introduce an interesting approach to overcome the limitations of the traditional antibody therapy. In the present study, B cells of immunized volunteers were used to construct a human single-chain fragment (HuscFv) library.

MATERIALS AND METHODS

The library was constructed with the maximum combination of heavy and light chains. As an antigen, Diphtheria toxoid (DTd) was used in four-round phage bio-panning to select phage clones that display DTd bound HuscFv from the library. After panning, individual scFv clones were selected. Clones that were able to detect DTd in an initial screening assay were transferred to Escherichia coli HB2151 to express the scFvs and purification was followed by Ni metal ion affinity chromatography. Toxin neutralization test was performed on Vero cells. The reactivity of the soluble scFv with diphtheria toxin were done and affinity calculation based on Beatty method was calculated.

RESULTS

The size of the constructed scFv library was calculated to be 1.3 × 106 members. Following four rounds of selection, 40 antibody clones were isolated which showed positive reactivity with DTd in an ELISA assay. Five clones were able to neutralize DTd in Vero cell assay. These neutralizing clones were used for soluble expression and purification of scFv fragments. Some of these soluble scFv fragments show neutralizing activity ranging from 0.6 to 1.2 µg against twofold cytotoxic dose of diphtheria toxin. The affinity constant of the selected scFv antibody was determined almost 107 M-1.

CONCLUSION

This study describes the prosperous construction and isolation of scFv from the immune library, which specifically neutralizes diphtheria toxin. The HuscFv produced in this study can be a potential candidate to substitute the animal antibody for treating diphtheria and detecting toxins.

The Role of Dexmedetomidine in Airway Management for Tracheostomy in Pediatric Patient with Obstructed Airway Due to Diphtheria: A Case Report

Introduction

Diphtheria is an infectious disease caused by exotoxin-producing Corynebacterium diphteriae and was a leading cause of death in childhood during the prevaccine era. This toxin is usually localized in the upper respiratory tract and may cause fatal airway obstruction. Many have used orotracheal intubation to secure the airway in diphtheria cases. However, the efficacy of tracheostomy under sedation while maintaining spontaneous ventilation and analgesia using trans-tracheal and superficial cervical block remains to be elucidated.

Case Presentation

A 6-year-old presented to the emergency room with respiratory distress and was diagnosed with diphtheria. A thick membrane in the oropharyngeal area and chest X-ray showed infiltrations indicative of pneumonia. The patient successfully underwent emergency tracheostomy under sedation using a combination of sevoflurane and dexmedetomidine to achieve prompt sedation and trans-tracheal injection and bilateral superficial cervical block as analgesia for the intra-tracheal and the incision. The patient's condition deteriorated the next day, and the bronchoscopy showed that the carina and main bronchus were covered by a pseudomembrane, obstructing the airway below the tracheostomy. The patient eventually died two days after admission.

Conclusions

Dexmedetomidine has minimal impact on ventilatory function and anti-sialagogue properties, while sevoflurane has minimal effect on respiratory depression. This case presentation showed that a combination of sevoflurane and dexmedetomidine with spontaneous assisted ventilation could be helpful in tracheostomy procedures in pediatric patients with airway obstruction due to diphtheria, along with the use of trans-tracheal and superficial cervical block as the analgesia. This report also indicates that being vigilant in rapidly-progressing and fatal pediatric diphtheria cases is vital.

An Observational Study on Association of Clinical Outcome of Diphtheria Cases with Immunization Status: A Tertiary Care Hospital, Jaipur

BACKGROUND

Diphtheria is an important vaccine preventable disease with varied outcome from mild to death. It was observed that the outcome also gets affected with status of immunization. The outcome is relatively milder in immunized children.

OBJECTIVE

To find out the clinical presentation and outcome of diphtheria cases and its association with the immunization status.

METHODS

A descriptive analysis of 64 diphtheria cases admitted from January 2019 to May 2020 at SMS hospital, a tertiary care referral hospital in Jaipur.

RESULTS

Half of (51.56%, 33/60) patients were in the age group of 6-10 years. The peak load (48.44%) of diphtheria cases was seen in the monsoon season. Around 60% of the patients were fully immunized and around 10% partially immunized, every third case was un-immunized. The most common complication was neurological in 13 cases (20.31%), followed by cardiac complications in 11 cases (17.19%), and respiratory (7.81%). The proportion of complication was much lower (26.3%) in immunized cases as compare to partially immunized and un immunized. The proportion of myocarditis was significantly higher in un immunized cases (40%) than partially immunized (16.7%) and filly immunized group (5.3%). Similarly, Bronchopneumonia was also significantly higher (20%) in unimmunized.

CONCLUSION

Our study depicted that there has been a shift of age above 5 years for diphtheria which suggests the need for the booster dose. Also high chances of complications are seen in unimmunized and partially immunized calling for public awareness regarding complete immunization.

"An Observational Study on Association of Clinical Diagnosis of Diphtheria with Smear and Culture Test: A Tertiary Care Hospital, Jaipur"

Diphtheria is an acute infectious upper respiratory tract disease caused by toxigenic strains of Corynebacterium diphtheria and can lead to significant morbidity and mortality in all the age groups. Most of the time diagnosis of diphtheria is clinical. There may be a dirty white patch covering one or both tonsils on examination for which throat swabs are collected for Kleb's-Loeffler's Bacillus (KLB) by direct microscopy and for culture and sensitivity of the organism. To find out the association between clinical diagnosis of diphtheria with smear and culture positivity. 674 cases of Clinical diphtheria were admitted from June 2017 to September 2020 at a tertiary care hospital, Sawai Mansingh Hospital, Jaipur. throat, difficulty in swallowing and swelling in the neck. Out of 674 patients of clinical diphtheria, majority 610 cases (90.5%) were found to have both KLB smear and culture negative. 13 cases (1.9%) were found to have both KLB smear and culture positive. 19 cases (2.8%) were found to have KLB smear positive and culture negative and remaining 32 cases (4.8%) were found to have KLB smear negative and culture positive. Out of 19 patients of KLB smear positive,11 cases (3.5%) were found to have complications. Out of 32 culture positive patients,24 cases (7.7%) were found to have complications. Out of 13 patients of both KLB smear and culture positive,11 cases (3.5%) were found to have complications. Our study concluded that the negative report of KLB smear and culture does not rule out diphtheria and it is evident that percentage of complication is high in patients with either KLB smear or culture or both positive with respect to both being negative. The correlation is found to be significant (p < 0.001).

Diphtheritic Myocarditis Patient with an Impending Upper Airway Compromise

How to cite this article: Jha AK, Padala SRAN, Parida S, Mishra SK. Diphtheritic Myocarditis Patient with an Impending Upper Airway Compromise. Indian J Crit Care Med 2022;26(10):1153-1154.

Production of IgY polyclonal antibody against diphtheria toxin and evaluation of its neutralization effect by Vero cell assay

BACKGROUND

Diphtheria is a bacterial disease which is caused by Corynebacterium diphtheriae. The symptoms are due to the diphtheria toxin produced by the bacteria. Antibiotic therapy and the use of diphtheria antitoxin is a recommended strategy to control diphtheria. Although mammalian antibodies are used to treat patients, IgY antibody has advantages over mammalian ones, including cost-effectiveness and production through non-invasive means. Moreover, in contrast to mammalian antibodies, IgY does not bind to the rheumatoid factor and does not activate the complement system. The objective of this study was to evaluate the in vitro neutralizing effect of IgY against diphtheria toxin.

RESULTS

Anti-DT IgY was produced by immunization of the laying white leghorn chickens. Indirect enzyme-linked immunosorbent assay revealed successful immunization of the animals, and the IgY was purified with a purity of 93% via polyethylene glycol precipitation method. The neutralizing activity of the purified IgY was evaluated by Vero cell viability assay. This assay confirmed that 1.95 μg (8.6 μg/ml of culture medium) of anti-DT IgY would neutralize 10 fold of cytotoxic dose 99% of DT, which was 0.3 ng (1.33 ng/ml of culture medium).

CONCLUSION

This anti-DT IgY may be applicable for diphtheria treatment and quality controls in vaccine production.

Spatiotemporal persistence of multiple, diverse clades and toxins of Corynebacterium diphtheriae

Diphtheria is a respiratory disease caused by the bacterium Corynebacterium diphtheriae. Although the development of a toxin-based vaccine in the 1930s has allowed a high level of control over the disease, cases have increased in recent years. Here, we describe the genomic variation of 502 C. diphtheriae isolates across 16 countries and territories over 122 years. We generate a core gene phylogeny and determine the presence of antimicrobial resistance genes and variation within the tox gene of 291 tox+ isolates. Numerous, highly diverse clusters of C. diphtheriae are observed across the phylogeny, each containing isolates from multiple countries, regions and time of isolation. The number of antimicrobial resistance genes, as well as the breadth of antibiotic resistance, is substantially greater in the last decade than ever before. We identified and analysed 18 tox gene variants, with mutations estimated to be of medium to high structural impact.

ST534: the new sequence type of Corynebacterium diphtheriae causing diphtheria in Jakarta and surrounding areas, Indonesia

Background/aim

The aim of this study was to find out characteristics and patterns of the spread of Corynebacterium diphtheriae isolated from Jakarta and the surrounding areas, using the whole genome sequencing (WGS) technique and multilocus sequence typing (MLST) approach.

Materials and methods

The study samples consisted of 86 C. diphtheriae isolates, which were isolated from diphtheria patients and close contacts of patients. The DNA sequencing was carried out using the WGS technique. Data conversion applied the U-gene software. Molecular typing was conducted through the MLST approach, then followed by online data analysis.

Results

The results showed that as many as 43 (50%) of all samples examined were new types with the same allele profile, namely 9-1-13-4-3-3-4. New sequence type C. diphtheriae is registered in the MLST global database as ST534 based on the allele profile. The tox gene analysis in 43 isolates with ST534 indicated that there were three mutation positions, all of which were silent mutations.

Conclusion

The main cause of diphtheria in Jakarta and the surrounding areas is a new sequence type of C. diphtheriae registered as ST534.

Diphtheritic angina in the tongue and floor of the mouth: unusual presentation

Diphtheria is an infectious disease caused by Corynebacterium diphtheriae, and is generally characterised by proliferation of the bacteria in the upper respiratory tract, formation of a pseudomembrane, and systemic diffusion of the diphtheria toxin throughout the body. We present the case of a young man with pseudomembranous plaques on the tongue and floor of the mouth, who received systemic and locoregional medical treatment, with a satisfactory outcome after 14 days.

The outbreak of diphtheria in Indonesia

Diptheria is commonly caused by the aerobic gram-positive bacteria, corynebacterium diphtheria. We herein report an unusual case of diphtheria outbreak in Indonesia in 2017 and its possible causes and current management.

Insights to the diphtheria toxin encoding prophages amongst clinical isolates of Corynebacterium diphtheriae from India

Diphtheria is a dreadful disease caused by Corynebacterium diphtheriae. Lysogenised bacteriophages carrying toxin gene in C. diphtheriae can make the strain toxigenic. However, such phage disseminates the toxin genes to other strains when it undergoes lytic phase. As little is known about the phage diversity in C. diphtheriae in India, the present study was undertaken to investigate the prophages integrated into the genome of 29 clinical isolates of C. diphtheriae using whole-genome shotgun sequencing. Amongst these isolates, 27 were toxigenic, while 2 were non-toxigenic strains. Of the 27 toxigenic strains, all harbored known phages carrying toxin gene and two other phages with unknown function. However, the two non-toxin strains did not harbour any of the phages in the genome. It is imperative to devise prevention strategies that hinder the dissemination of toxin by prophages, as it may increase the complications of diphtheria post-immunisation.

Diphtheria in Children in Northern Haiti

Infection with Corynebacterium diphtheriae persists in Haiti. Twenty-six children with clinically severe respiratory diphtheria presented to a hospital in northern Haiti during a 3-year period beginning in early 2015. The mortality rate was 50%. Partial or absent vaccinations as well as delayed and limited care contributed to mortality. This cohort offer insights into the multiple challenges involved in preventing and caring for children with diphtheria in resource-limited settings.

Assessing the Importance of Domestic Vaccine Manufacturing Centers: An Overview of Immunization Programs, Vaccine Manufacture, and Distribution

Vaccines have significantly reduced the detrimental effects of numerous human infectious diseases worldwide, helped to reduce drastically child mortality rates and even achieved eradication of major pathogens, such as smallpox. These achievements have been possible due to a dedicated effort for vaccine research and development, as well as an effective transfer of these vaccines to public health care systems globally. Either public or private institutions have committed to developing and manufacturing vaccines for local or international population supply. However, current vaccine manufacturers worldwide might not be able to guarantee sufficient vaccine supplies for all nations when epidemics or pandemics events could take place. Currently, different countries produce their own vaccine supplies under Good Manufacturing Practices, which include the USA, Canada, China, India, some nations in Europe and South America, such as Germany, the Netherlands, Italy, France, Argentina, and Brazil, respectively. Here, we discuss some of the vaccine programs and manufacturing capacities, comparing the current models of vaccine management between industrialized and developing countries. Because local vaccine production undoubtedly provides significant benefits for the respective population, the manufacture capacity of these prophylactic products should be included in every country as a matter of national safety.

Cardiac complications in diphtheria and predictors of outcomes

OBJECTIVE

To study the cardiac complications in diphtheria patients and to study the predictors of outcomes.

STUDY DESIGN

Single centre prospective analysis of cardiac complications in diphtheria patients.

RESULTS

In this study, there were 60 patients diagnosed with diphtheria with ECG changes. The ECG changes seen were sinus tachycardia (68.3%), T wave inversion (20%), ST segment depression (13.3%), right bundle branch block (5%), multiple atrial ectopics (3.3%). The case fatality rate in our study was 25% (15 patients). High CPK-MB, myoglobulin and cardiac troponin levels were associated with cardiac mortality. In our study, cardiac troponin T had the highest sensitivity (80%) and CK-MB had the highest specificity (95.56%).

CONCLUSION

Cardiac involvement is a common complication of infection with C. diphtheria and is associated with high mortality. As diphtheria can be prevented by adequate vaccination, efforts should be maximized for high vaccine coverage with booster doses.

Prospective Study of Diphtheria for Neurological Complications

Aim

To study the spectrum of neurological complications of diphtheria, timing of onset with respect to respiratory disease, and pattern of recovery.

Settings and Design

Prospective, observational, hospital-based study conducted in tertiary care hospital.

Materials and Methods

Twenty-eight cases of diphtheria with neurological complications were admitted during the period of study. Demographic profile, age, gender, status of immunization, past history stressing on the severity of the respiratory disease, and complaints regarding diverse complications of diphtheria were recorded. Detailed clinical and central nervous system examinations along with relevant investigations were carried out.

Results

Children were in the age group of 3-18 years. All 28 children presented with bulbar symptoms. Isolated palatal palsy was present in 18 children (64%). Third cranial involvement was present in four children. Three children had unilateral lower motor neuron facial palsy and one child had sixth cranial nerve palsy. Nine children developed symmetric limb weakness. Diaphragmatic palsy was present in three children with the onset from 1-3 weeks after pharyngeal diphtheria. Loss of vasomotor tone was present in two children. Recovery was complete in all 28 children.

Conclusion

Pediatricians/neurophysicians should have a high index of suspicion to recognize diphtheritic polyneuropathy. It carries good prognosis, hence timely diagnosis and differentiation from other neuropathies is a prerequisite for rational management and contact tracing.

Epidemiology of Diphtheria in India, 1996-2016: Implications for Prevention and Control

Diphtheria is an acute disease caused by exotoxin-producing Corynebacterium diphtheriae. Globally, diphtheria has been showing a declining trend due to effective childhood vaccination programs. A substantial proportion of global burden of diphtheria is contributed by India. Hospital-based surveillance studies as well as diphtheria outbreaks published in last 20 years (1996-2016) indicate that diphtheria cases are frequent among school-going children and adolescents. In some Indian states, Muslim children are affected more. As per the national level health surveys, coverage of three doses of diphtheria vaccine was 80% during 2015-2016. Information about coverage of diphtheria boosters is not routinely collected through these surveys, but is expected to be low. Few studies also indicate low diphtheria immunity among school-going children and adults. The strategies for prevention of diphtheria need to focus on improving coverage of primary and booster doses of diphtheria vaccines administered as a part of Universal Immunization Program as well as introducing diphtheria vaccine for school-going children.