Prolongation of Acid-Fast Bacilli Sputum Smear Positivity in Patients with Multidrug-Resistant Pulmonary Tuberculosis.

The study sought to determine factors associated with prolonged smear positivity in multidrug-resistant tuberculosis (MDR-TB) patients following appropriate management. Newly diagnosed patients were enrolled between June 2017 and May 2018. Sputum samples were collected for Xpert® MTB/RIF and line probe assays (LiPAs). Microscopic tests were performed at baseline and 4, 8, and 12 weeks post-anti-TB therapy. Of the 200 patients, 114 (57%) were HIV-positive. After 12 weeks of treatment, there was a significant microscopy conversion rate among DS-TB patients compared to MDR-TB patients irrespective of their HIV status (p = 0.0013). All MDR-TB patients who had a baseline smear grade ranging from scanty to +1 converted negative, while 25% ranging from +2 to +3 remained positive until the end of 12 weeks (p = 0.014). Factors associated with smear positivity included age <35 years (p = 0.021), initial CD4+ T-cell count ≥200 cells/mm3 (p = 0.010), and baseline smear grade ≥2+ (p = 0.014). Cox regression showed that only the baseline smear grade ≥2+ was independently associated with prolonged smear positivity in MDR-TB patients (p = 0.011) after adjusting for HIV status, CD4+ T-cell count, and age. Baseline sputum smear grade ≥2+ is a key determinant for prolonged smear positivity beyond 12 weeks of effective anti-TB therapy in MDR-TB patients.

Phylogenetic analysis of carbapenem-resistant Acinetobacter baumannii isolated from different sources using Multilocus Sequence Typing Scheme.

The emergence and worldwide distribution of carbapenem-resistant Acinetobacter baumannii strains has become a major public health threat. The objective of this study was to investigate the clonal relatedness of A. baumannii isolates collected from clinical and extra-hospital environments in Mthatha, South Africa. Forty carbapenem-resistant isolates comprising of clinical (20) and extra-hospital (20) were identified and tested for antimicrobial susceptibility. Detection of carbapenemase encoding genes was performed by Real-time PCR. The clonal relationship of clinical isolates relative to extra-hospital isolates was determined via multilocus sequence typing (MLST). All isolates (clinical and extra-hospital) were resistant to most common antibiotics including carbapenems (imipenem; MIC ≥32 µg/mL and meropenem; MIC ≥32 µg/mL) with the only exception being amikacin (with 3 isolates susceptible), tigecycline (14 isolates susceptible) and colistin (all isolates susceptible). The bla OXA-23-like and the intrinsic bla OXA-51 -like genes were detected in all the isolates tested. The bla OXA-58-like and bla IMP-type genes were detected in 2 clinical isolates whilst the bla OXA-24-like, bla VIM-type, bla NDM-1, bla SIM, and bla AmpC were not detected. The bla OXA-24-like, bla OXA-58-like, bla IMP-type, bla VIM-type, bla NDM-1, bla SIM, and bla AmpC were negative in the extra-hospital isolates. Co-occurrence of bla OXA-23 -like, bla OXA-58-like and bla IMP-type was observed in 2 clinical isolates. The MLST performed on 33 isolates identified 5 existing sequence types (ST) (ST1, ST2, ST25, ST85 and ST215) in clinical isolates and 2 existing STs (ST1 and ST2) in extra-hospital isolates. The most dominant ST was ST2 accounting for 68.8% of the clinical isolates and 82.4% of the extra-hospital isolates. The study demonstrated high prevalence and potential clonal spread of globally-disseminated clonal complex 2 carrying bla OXA-23-like within our local settings. However, ST25 might be an emerging lineage carrying the bla OXA-23-like . Continuous monitoring is important in limiting the spread of these strains in other healthcare settings and the community.

Detection of extended spectrum beta-lactamase genes in Pseudomonas aeruginosa isolated from patients in rural Eastern Cape Province, South Africa.

The proliferation of extended spectrum beta-lactamase (ESBL) producing Pseudomonas aeruginosa represent a major public health threat. In this study, we evaluated the antimicrobial resistance patterns of P. aeruginosa strains and characterized the ESBLs and Metallo- ß-lactamases (MBL) produced. Strains of P. aeruginosa cultured from patients who attended Nelson Mandela Academic Hospital and other clinics in the four district municipalities of the Eastern Cape between August 2017 and May 2019 were identified; antimicrobial susceptibility testing was carried out against thirteen clinically relevant antibiotics using the BioMérieux VITEK 2 and confirmed by Beckman autoSCAN-4 System. Real-time PCR was done using Roche Light Cycler 2.0 to detect the presence of ESBLs; blaSHV, blaTEM and blaCTX-M genes; and MBLs; blaIMP, blaVIM. Strains of P. aeruginosa demonstrated resistance to wide-ranging clinically relevant antibiotics including piperacillin (64.2%), followed by aztreonam (57.8%), cefepime (51.5%), ceftazidime (51.0%), piperacillin/tazobactam (50.5%), and imipenem (46.6%). A total of 75 (36.8%) multidrug-resistant (MDR) strains were observed of the total pool of isolates. The blaTEM, blaSHV and blaCTX-M was detected in 79.3%, 69.5% and 31.7% isolates (n = 82), respectively. The blaIMP was detected in 1.25% while no blaVIM was detected in any of the strains tested. The study showed a high rate of MDR P. aeruginosa in our setting. The vast majority of these resistant strains carried blaTEM and blaSHV genes. Continuous monitoring of antimicrobial resistance and strict compliance towards infection prevention and control practices are the best defence against spread of MDR P. aeruginosa.

Molecular basis of virulence in clinical isolates of Escherichia coli and Salmonella species from a tertiary hospital in the Eastern Cape, South Africa.

BACKGROUND: Apart from localized gastrointestinal infections, Escherichia coli and Salmonella species are major causes of systemic disease in both humans and animals. Salmonella spp. cause invasive infections such as enteric fever, septicemia, osteomyelitis and meningitis while certain types of E. coli can cause systemic infections, includingpyelonephritis, meningitis and septicemia. These characteristic requires the involvement of a myriad of virulence factors. METHODS: This study investigated the virulence factors of Escherichia coli and Salmonella species in clinical specimens from patients with diarrhoea presenting to health care centres in Oliver R. Tambo District Municipality, Eastern Cape Province, Republic of South Africa. Microbiology analysis involved the use of cultural and molecular techniques. RESULTS: Out of a total of 315 samples screened, Salmonella isolates were obtained in 119 (37.8%) of cases and these comprised: S. choleraesuis (6%), S. enteritidis (4%), S. eppendorf (1%), S. hadar (1%), S. isangi (8%), S. panama (1%), S. typhi (52%), S. typhimurium (25%) and untyped Salmonella spp. (2%). Among the Salmonella species 87 (73.1%) were invasive. Using molecular diagnostic methods, diarrheagenic E. coli were detected in 90 cases (28.6%): the greater proportion of this were enteroaggregative E. coli (EAEC) 37 (41.1%), enteropathogenic E. coli (EPEC) 21 (23.3%) and enterohemorrhagic E. coli (EHEC) 21 (23.3%). The predominant virulence gene among the diarrheagenic E. coli was EAEC heat-stable enterotoxin astA genes while the virulence genes identified in the Salmonella strains were 15 (12.6%) flic and 105 (88.2%) inv genes. The amino acid identity of the representative genes showed 95-100% similarity to corresponding blast searched sequence. CONCLUSIONS: This study showed the diversity of virulence gene expression in two major enteric pathogens. S. typhi and enteroaggregative E. coli were the predominant enteropathogens in our study area with an indication that EAEC is endemic within our study population. It was observed among other things that some diarrheagenic E. coli isolated from apparently asymptomatic subjects expressed some virulence genes at frequency as high as seen in diarrheagenic cases. This study underlines the importance of understanding the virulence composition and diversity of pathogens for enhanced clinico-epidemiological monitoring and health care delivery.

Evaluation of the antibacterial and anticancer activities of some South African medicinal plants.

BACKGROUND: Several herbs are traditionally used in the treatment of a variety of ailments particularly in the rural areas of South Africa where herbal medicine is mainly the source of health care system. Many of these herbs have not been assessed for safety or toxicity to tissue or organs of the mammalian recipients. METHODS: This study evaluated the cytotoxicity of some medicinal plants used, inter alia, in the treatment of diarrhoea, and stomach disorders. Six selected medicinal plants were assessed for their antibacterial activities against ampicillin-resistant and kanamycin-resistant strains of Escherichia coli by the broth micro-dilution methods. The cytotoxicities of methanol extracts and fractions of the six selected plants were determined using a modified tetrazolium-based colorimetric assay (3-(4, 5-dimethylthiazol)-2, 5-diphenyl tetrazolium bromide (MTT) assay). RESULTS: The average minimum inhibitory concentration (MIC) values of the plants extracts ranged from 0.027 mg/mℓ to 2.5 mg/mℓ after 24 h of incubation. Eucomis autumnalis and Cyathula uncinulata had the most significant biological activity with the least MIC values. The in vitro cytotoxicity assay on human hepatocarcinoma cell line (Huh-7) revealed that the methanol extract of E. autumnalis had the strongest cytotoxicity with IC(50) of 7.8 µg/mℓ. Ethyl acetate and butanol fractions of C. uncinulata, Hypoxis latifolia, E. autumnalis and Lantana camara had lower cytotoxic effects on the cancer cell lines tested with IC(50) values ranging from 24.8 to 44.1 µg/mℓ; while all the fractions of Aloe arborescens and A. striatula had insignificant or no cytotoxic effects after 72 h of treatment. CONCLUSIONS: Our results indicate that the methanol fraction of E. autumnalis had a profound cytotoxic effect even though it possessed very significant antibacterial activity. This puts a query on its safety and hence a call for caution in its usage, thus a product being natural is not tantamount to being entirely safe. However, the antibacterial activities and non-cytotoxic effects of A. arborescens and A. striatula validates their continuous usage in ethnomedicine.

Bacteriological Profile and Antibiogram of Aerobic Burn Wound Isolates in Mthatha; Eastern Cape; South Africa

Burn wound colonisation and infection is not only associated with delayed wound healing and scar formation; but may also lead to sepsisrelated mortality. A wide variety of microorganisms; like staphylococcus aureus; Pseudomonas aeruginosa; and Enterobacteriaceae-like Klebsiella pneumoniae and Escherichia coli; are involved. Resistance is generally increasing; with reports of multidrug-and pan-resistant isolates. This study was conducted to determine the common aerobic bacterial isolates in our setting and describe their antimicrobial susceptibility. This retrospective; descriptive study was carried out on 243 patients; from whom 312 burn wound specimens were received by the Nelson Mandela Academic Hospital microbiology laboratory of the National Health Laboratory Service; Mthatha. All samples were processed according to standard laboratory protocols; isolates were tabulated according to age and gender of the patients; and their percentage susceptibilities to relevant antibacterials were computed. A total of 229 patient specimens showed growth on culture. The total number of isolates was 629; out of which 269 were Gram-positive cocci and 360 were Gram-negative bacilli. The commonest organism was S. aureus (27.7); followed by K. pneumoniae (13.4); Proteus mirabilis (12.4); Group D streptococcus (9.4); P. aeruginosa (8.9) and E. coli (6.2). A generally high level of resistance was observed in many organisms. Methicillinresistant S. aureus accounted for 57.5 of the S. aureus. Resistance among the Gram-negative bacilli was; in general; least to imipenem; amikacin and ciprofloxacin. The common organisms causing burn wound infections in our setting include staphylococci; Klebsiella; Proteus and Pseudomonas and there is a high level of resistance against commonly used antimicrobials. Regular surveillance of burn wound organisms and their antimicrobial resistance patterns will help in determining empirical antibiotic therapy for subsequent related septic events