Hypervirulent Klebsiella pneumoniae in a South African tertiary hospital-Clinical profile, genetic determinants, and virulence in Caenorhabditis elegans.

Introduction: A distinct strain of Klebsiella pneumoniae (K. pneumoniae) referred to as hypervirulent (hvKp) is associated with invasive infections such as pyogenic liver abscess in young and healthy individuals. In South Africa, limited information about the prevalence and virulence of this hvKp strain is available. The aim of this study was to determine the prevalence of hvKp and virulence-associated factors in K. pneumoniae isolates from one of the largest tertiary hospitals in a South African province. Methods: A total of 74 K. pneumoniae isolates were received from Pelonomi Tertiary Hospital National Health Laboratory Service (NHLS), Bloemfontein. Virulence-associated genes (rmpA, capsule serotype K1/K2, iroB and irp2) were screened using Polymerase Chain Reaction (PCR). The iutA (aerobactin transporter) gene was used as a primary biomarker of hvKp. The extracted DNAs were sequenced using the next-generation sequencing pipeline and the curated sequences were used for phylogeny analyses using appropriate bioinformatic tools. The virulence of hvKp vs. classical Klebsiella pneumoniae (cKp) was investigated using the Caenorhabditis elegans nematode model. Results: Nine (12.2%) isolates were identified as hvKp. Moreover, hvKp was significantly (p < 0.05) more virulent in vivo in Caenorhabditis elegans relative to cKp. The virulence-associated genes [rmpA, iroB, hypermucoviscous phenotype (hmv) phenotype and capsule K1/K2] were significantly (p < 0.05) associated with hvKp. A homology search of the curated sequences revealed a high percentage of identity between 99.8 and 100% with other homologous iutA gene sequences of other hvKp in the GenBank. Conclusion: Findings from this study confirm the presence of hvKp in a large tertiary hospital in central South Africa. However, the low prevalence and mild to moderate clinical presentation of infected patients suggest a marginal threat to public health. Further studies in different settings are required to establish the true potential impact of hvKp in developing countries.

Prevalence and occupational exposure to zoonotic diseases in high-risk populations in the Free State Province, South Africa.

Introduction: Zoonotic diseases are responsible for 2.5 billion human cases globally and approximately 2.7 million deaths annually. Surveillance of animal handlers and livestock for zoonotic pathogens contributes to understanding the true disease burden and risk factors within a community. This study investigated the prevalence of selected zoonoses in cattle, farm workers and occupational exposure to endemic zoonotic diseases and their associated risk factors. Methods: Sputum samples from farmworkers were screened for Mycobacterium bovis. Blood specimens from farmworkers and archived sera were tested for serological evidence of Brucella sp., hantaviruses, and Leptospira sp. Communal and commercial cattle herds were tested for bovine tuberculosis and brucellosis. Results: Mycobacterium bovis was not isolated from human samples. A total of 327 human sera were screened, and 35/327 (10.7%) were Brucella sp. IgG positive, 17/327 (5.2%) Leptospira sp. IgM positive, and 38/327 (11.6%) hantavirus IgG positive (95% CI). A higher proportion of Brucella sp. IgG-positive samples were detected among veterinarians (value of p = 0.0006). Additionally, two cattle from a commercial dairy farm were bovine tuberculosis (bTB) positive using the bTB skin test and confirmatory interferon-gamma assay. A higher percentage of confirmed brucellosis-positive animals were from communal herds (8.7%) compared to commercial herds (1.1%). Discussion: These findings highlight the brucellosis and M. bovis prevalence in commercial and communal herds, the zoonotic disease risk in commercial and subsistence farming in developing countries, and the occupational and rural exposure risk to zoonotic pathogens.

Diagnosis of laryngeal tuberculosis in a high TB burden area.

PURPOSE: The larynx is the second most commonly affected site in the head and neck region in patients with extrapulmonary tuberculosis (TB). Despite this, the prevalence of laryngeal TB is largely unknown, particularly in areas with a high TB burden. The laboratory diagnosis of TB includes microscopy, culture and molecular testing. The aims of this study were to determine the prevalence of laryngeal TB in patients presenting with laryngeal pathology in a region with a high TB burden and to determine the optimal diagnostic methods for the diagnosis of laryngeal TB. METHODS: This was a prospective descriptive study of 80 adult patients undergoing direct laryngoscopy and biopsy for laryngeal pathology in the Department of Otorhinolaryngology, Universitas Academic Hospital, Bloemfontein, South Africa over a 1 year period. Histopathological and microbiological investigations (microscopy, Xpert MTB/RIF, and TB culture) were performed on all laryngeal biopsies. RESULTS: Five (6.25%) out of 80 patients were diagnosed with laryngeal TB. In one patient, the Xpert MTB/RIF assay was positive on the laryngeal tissue and histology showed granulomas. Two patients had granulomas on histology although the microbiological tests on the tissue were negative. Two patients had only positive tissue cultures for Mycobacterium tuberculosis. None of the biopsies had positive Ziehl-Neelsen stains. CONCLUSION: The results suggest that the diagnosis of laryngeal TB required a combination of histopathology, culture and PCR and that the Xpert MTB/RIF assay is not a sensitive test for the diagnosis of laryngeal TB.

The prevalence and bacterial distribution of peritonitis amongst adults undergoing continuous ambulatory peritoneal dialysis at Universitas hospital.

BACKGROUND: Peritonitis is the leading cause of morbidity and technique failure in peritoneal dialysis (PD) patients. The International Society for Peritoneal Dialysis (ISPD) recommends each centre to monitor the peritonitis rates and the causative organisms in order to guide local empiric antibiotic protocols. The aim of this study was to report on the peritonitis rates and describe the causative microorganisms and the antibiotic susceptibility in continuous ambulatory peritoneal dialysis (CAPD) adult patients at the Universitas Academic Hospital. METHODS: A single-centre, retrospective descriptive survey was conducted to determine the peritonitis rates in PD patients (January-December 2016). All CAPD patients aged ≥18 years, who presented with clinical features of PD-associated peritonitis, were included. The peritonitis episodes were studied per patient, and the causative microorganisms and the antibiotic susceptibility of the organisms were described. RESULTS: One hundred and twenty-eight patients underwent CAPD. The peritonitis rate was 1.45 episodes per year at risk. The prevalence of CAPD patients affected by at least one episode of CAPD-associated peritonitis during 2016 was 56.3%. The majority of episodes (76.7%) (n = 122) were mono-microbial. Gram-positive organisms accounted for 73.0% (n = 116) of the peritonitis episodes, coagulase-negative Staphylococcus being the most common. Gram-negative organisms accounted for 15.7% (n = 25) of the peritonitis episodes, and the common pathogens was Enterobacteriaceae. CONCLUSION: The peritonitis rate was alarmingly high, with 1.45 episodes per year at risk; this is three times more than the recommended 0.5 episodes per year according to the ISPD guidelines. The culture-negative rate of 8.8% is within ISPD-acceptable limits. There is a need to strengthen preventive measures with regard to peritonitis.

Risk Factors for Zoonotic Tuberculosis at the Wildlife-Livestock-Human Interface in South Africa.

A cross-sectional study was conducted to investigate the risk factors associated with zoonotic tuberculosis in humans and its transmission to people living at the wildlife-livestock-human interface. A questionnaire was administered to collect information on food consumption habits, food handling practices, and knowledge of zoonotic TB. Sputum samples were also collected from 150 individuals that belonged to households of cattle farmers with or without a bTB infected herd. In addition, 30 milk samples and 99 nasal swabs were randomly collected from cattle in bTB infected herds for isolation of Mycobacterium bovis (M. bovis). The sputum samples were screened for TB using the GeneXpert test and this was followed by mycobacterial culture and speciation using molecular techniques. No M. bovis was isolated from TB positive sputum samples and only one sample was confirmed as Mycobacterium tuberculosis (M. tuberculosis). M. bovis was isolated from 6.6% (n = 2/30) milk samples and 9% (n = 9/99) of nasal swabs. Ownership of a bTB infected herd and consumption of milk were recognized as highly significant risk factors associated with a history of TB in the household using multiple correspondence analysis (MCA) and logistic regression. The findings from this study have confirmed the potential for zoonotic TB transmission via both unpasteurized milk and aerosol thus, the role of M. bovis in human TB remains a concern for vulnerable communities.

Spillover of Mycobacterium bovis from wildlife to livestock, South Africa.

During August 2012-February 2013, bovine tuberculosis was detected in communal livestock bordering the Greater Kruger National Park Complex (GKNPC) in South Africa. Using spacer oligonucleotide and variable number tandem repeat typing, we identified the Mycobacterium bovis strain endemic in GKNPC wildlife. Our findings indicate bovine tuberculosis spillover from GKNPC wildlife to neighboring livestock.