Antimicrobial resistance genetic determinants and susceptibility profile of Pseudomonas aeruginosa isolated from clinical samples in a tertiary hospital in Ogun State, Nigeria.

BACKGROUND: Genetic determinants are known to promote antibiotic resistance through horizontal gene transfer. METHODS: We molecularly characterized integrons, plasmid replicon types and metallo-ß-lactamase-encoding genes of 38 Pseudomonas aeruginosa strains isolated from clinical samples. RESULTS: The P. aeruginosa isolates displayed high resistance (97.4%) to ß-lactams. Seventeen (44.74%) of them possessed plasmids. Of the 17 isolates that possessed plasmids, 11 (64.7%) of them harboured IncFIA plasmid replicon type, while 6 (35.3%), 5 (29.4%) and 5 (29.4%) were of the IncFIB, IncF and IncW types, respectively. The intI1 gene was detected in 19 (50%) of the isolates. The blaNDM-A, blaNDM-B and blaVIM genes were detected in 14 (35.9%), 4 (10.3%) and 5 (12.8%) of the isolates, respectively. CONCLUSIONS: High resistance to ß-lactams was observed among P. aeruginosa strains of clinical origin in this study. They possessed transmissible genetic elements indicating the potential for continuous dissemination, thus continuous surveillance is advocated.

Forty Years of Helicobacter pylori: The African Perspective.

BACKGROUND: Helicobacter pylori colonises 50% of the world population and is a causative agent of gastritis, peptic ulcer disease, mucosa associate lymphoid tissue lymphoma and gastric cancer. SUMMARY: In Africa, the prevalence rate has been found to be the highest in comparison to other parts of the world. Despite its high prevalence there are low rates of gastric cancer recorded in Africa. This African perspective gives an insight into the history of H. pylori in Africa and also examines the issue of the so-called "African Enigma," it's diagnosis and treatment and where we are now. KEY MESSAGES: Our vision is to have an African community that is free from H. pylori infections and complications. To this end, the African Helicobacter and Microbiota Study Group was initiated in 2021 and launched on the June 27, 2022 in Lagos, Nigeria (https://ahmsg-africa.org/). The African perspective includes the need for more detailed information on actual community and hospital prevalence, resistance data, and standardizing processes and algorithms to enable comparative diagnosis and therapy of H. pylori infections using a multi-pronged approach with international support.

Antibiotic Resistance and Plasmid Replicon Types of Non-Typhoidal Salmonella Serovars Isolated From Food Animals and Humans in Lagos, Nigeria.

Multidrug resistance and invasiveness of non-typhoidal Salmonella (NTS) serovars have in recent times brought to the fore the public health risk associated with salmonellosis. This study was aimed at profiling NTS serovars isolated from food animals and humans for their susceptibility to antibiotics and plasmid replicon types. Forty seven NTS serovars were profiled for their susceptibility to antibiotics using the disk diffusion method. Polymerase chain reaction based replicon typing assay was used for profiling plasmid replicon types detected in Salmonella isolates. High rate of resistance were found for amoxicillin/clavulanic acid (40/47; 85.1%), cefuroxime (38/47; 80.9%) and ceftazidime (30/47; 63.8%). Thirty one (65.9%) and 33 (70.2%) showed intermediate resistance to ofloxacin and ciprofloxacin respectively. Plasmids of sizes ranging from 14.3 to 16.7 kb were detected in 24 (51.1%) of Salmonella isolates with some serovars harbouring multiple plasmids. FIA, FIB, Frep and W plasmid replicon types were detected in 11, 4, 2 and 1 of the Salmonella isolates respectively. Three of the isolates harboured both FIA and FIB replicon types. The high rate of resistance to ß-lactams observed in Salmonella serovars harbouring different plasmid replicon types in this study highlight potential public health threat and the need for prudent use of antibiotics in human and veterinary medicine.

Helicobacter pylori Infection in Africa: Update of the Current Situation and Challenges.

BACKGROUND: The burden of Helicobacter pylori infection (HPI) in Africa remains high with varying levels of prevalence among children and adults reported in different regions of the continent. Persistent and uneradicated HPI could result in gastric cancer, although less severe pathological outcomes have been reported among Africans - the so-called "African enigma." SUMMARY: Analysis of endoscopic findings of the upper gastrointestinal tract demonstrates similarities with that of patients from the West. Thus, it could be asserted that the true picture of HPI in Africa is yet to be unveiled due to several challenges including inadequate health-care system, lack of treatment guidelines and standardized protocol for diagnosis, and lack of data. This review explores the prevalence, diagnosis, treatment, and health-care system in Africa as it relates to HPI, thus providing an update and highlighting the need for an African HPI guideline. KEY MESSAGES: There is high prevalence of Helicobacter pylori infection (HPI) in Africa with an increasing burden of antibiotic resistance. Various methods including invasive and noninvasive methods are deployed in the diagnosis of HPI in Africa. There is a need for consensus on diagnosis and treatment of HPI in Africa.

Molecular and phenotypic characterization of efflux pump and biofilm in multi-drug resistant non-typhoidal Salmonella Serovars isolated from food animals and handlers in Lagos Nigeria.

BACKGROUND: Multidrug resistance efflux pumps and biofilm formation are mechanisms by which bacteria can evade the actions of many antimicrobials. Antibiotic resistant non-typhoidal Salmonella serovars have become wide spread causing infections that result in high morbidity and mortality globally. The aim of this study was to evaluate the efflux pump activity and biofilm forming capability of multidrug resistant non-typhoidal Salmonella (NTS) serovars isolated from food handlers and animals (cattle, chicken and sheep) in Lagos. METHODS: Forty eight NTS serovars were subjected to antibiotic susceptibility testing by the disc diffusion method and phenotypic characterization of biofilm formation was done by tissue culture plate method. Phenotypic evaluation of efflux pump activity was done by the ethidium bromide cartwheel method and genes encoding biofilm formation and efflux pump activity were determined by PCR. RESULTS: All 48 Salmonella isolates displayed resistance to one or more classes of test antibiotics with 100% resistance to amoxicillin-clavulanic acid. Phenotypically, 28 (58.3%) of the isolates exhibited efflux pump activity. However, genotypically, 7 (14.6%) of the isolates harboured acrA, acrB and tolC, 8 (16.7%) harboured acrA, acrD and tolC while 33 (68.8%) possessed acrA, acrB, acrD and tolC. All (100%) the isolates phenotypically had the ability to form biofilm with 23 (47.9%), 24 (50.0%), 1 (2.1%) categorized as strong (SBF), moderate (MBF) and weak (WBF) biofilm formers respectively but csgA gene was detected in only 23 (47.9%) of them. Antibiotic resistance frequency was significant (p < 0.05) in SBF and MBF and efflux pump activity was detected in 6, 21, and 1 SBF, MBF and WBF respectively. CONCLUSION: These data suggest that Salmonella serovars isolated from different food animals and humans possess active efflux pumps and biofilm forming potential which has an interplay in antibiotic resistance. There is need for prudent use of antibiotics in veterinary medicine and scrupulous hygiene practice to prevent the transmission of multidrug resistant Salmonella species within the food chain.

Evaluation of efflux pump activity and biofilm formation in multidrug resistant clinical isolates of Pseudomonas aeruginosa isolated from a Federal Medical Center in Nigeria.

BACKGROUND: Pseudomonas aeruginosa an opportunistic pathogen, is widely associated with nosocomial infections and exhibits resistance to multiple classes of antibiotics. The aim of this study was to determine the antibiotic resistance profile, biofilm formation and efflux pump activity of Pseudomonas strains isolated from clinical samples in Abeokuta Ogun state Nigeria. METHODS: Fifty suspected Pseudomonas isolates were characterized by standard biochemical tests and PCR using Pseudomonas species -specific primers. Antibiotic susceptibility testing was done by the disc diffusion method. Efflux pump activity screening was done by the ethidium bromide method and biofilm formation assay by the tissue plate method. Genes encoding biofilm formation (pslA & plsD) and efflux pump activity (mexA, mexB and oprM) were assayed by PCR. RESULTS: Thirty-nine Pseudomonas spp. were identified of which 35 were Pseudomonas aeruginosa and 4 Pseudomonas spp. All 39 (100%) Pseudomonas isolates were resistant to ceftazidime, cefuroxime and amoxicillin-clavulanate. Thirty-six (92%), 10(25.6%), 20 (51.2%), 11(28%) and 9(23%) of the isolates were resistant to nitrofurantoin, imipenem, gentamicin, cefepime and aztreonam respectively. All the isolates had the ability to form biofilm and 11 (28%) of them were strong biofilm formers. They all (100%) harboured the pslA and pslD biofilm encoding genes. Varied relationships between biofilm formation and resistance to ciprofloxacin, ofloxacin, cefixime, gentamicin, imipenem, and aztreonam were observed. Only 23(59%) of the Pseudomonas isolates phenotypically exhibited efflux pump activity but mexA gene was detected in all 39 (100%) isolates while mexB and oprM genes were detected in 91%, 92%, and 88% of strong, moderate and weak biofilm formers respectively. CONCLUSION: Multidrug resistance, biofilm and efflux pump capabilities in Pseudomonas aeruginosa have serious public health implications in the management of infections caused by this organism.

Duodenal ulcer promoting gene (DupA), plasticity region genes and sigma factors in H. pyloristrains from Nigeria.

INTRODUCTION: Helicobacter pylori is a principal cause of gastric cancer. The aim of this study was to determine the prevalence and contribution of duodenal ulcer promoting gene A (dupA), the plasticity region genes and sigma factors in relation to their pathological expression of H. pylori infections in the Nigerian population. METHODOLOGY: Polymerase Chain Reaction was used to analyze a total of forty-nine H. pylori strains isolated from patients attending various endoscopic units in tertiary hospitals in Nigeria for complete dupA (G27 variant), jhp0917, jhp0918, other plasticity region genes jhp 914/917, jhp0914, jhp0940 and sigma factors. RESULTS: PCR results indicated that the prevalence of complete dupA (G27 variants), jhp0917, jhp0918 and other plasticity region genes jhp0914, jhp0914/0917 and jhp0940 in the H. pylori strains were 4%, 53%, 88%, 73%, 12% and 0% respectively. The prevalence values of the sigma factors were 96%, 92%, 80% for rpoN,  fliA and rpoD respectively. However, the endoscopic findings showed that erosion, normal mucosal, ulcer, hyperaemic stomach, mucosal atrophy and oedematous stomach in the patients where the H. pylori strains were isolated were 40.8%, 32.7%, 10.2%, 8.2%, 2.0% and 6.1% respectively. There was significant association between jhp0917, jhp914/917 and G27 variant and the endoscopic findings, while other plasticity genes showed no association with the endoscopic findings. CONCLUSION: These results suggest that the presence of jhp0917, jhp0914/917 and G27 variant could be used as marker to predict the pathological effect of severity in Nigeria patients with H. pylori infection.

Molecular diversity and antibiotic resistance gene profile of Salmonella enterica serovars isolated from humans and food animals in Lagos, Nigeria.

Outbreaks of Salmonellosis remain a major public health problem globally. This study determined the diversity and antibiotic resistance gene profile of Salmonella enterica serovars isolated from humans and food animals. Using standard methods, Salmonella spp. were isolated from fecal samples, profiled for antimicrobial susceptibility and resistance genes. Seventy-one Salmonella isolates were recovered from both humans and food animals comprising cattle, sheep, and chicken. Forty-four serovars were identified, with dominant Salmonella Budapest (31.8%). Rare serovars were present in chicken (S. Alfort, S. Wichita, S. Linton, S. Ealing, and S. Ebrie) and humans (S. Mowanjum, S. Huettwillen, S. Limete, and S. Chagoua). Sixty-eight percent of isolates were sensitive to all test antibiotics, while the highest rate of resistance was to nalidixic acid (16.9%; n = 12), followed by ciprofloxacin (11.3%; n = 8) and tetracycline (9.9%; n = 8). Five isolates (7%) were multidrug-resistant and antimicrobial resistance genes coding resistance to tetracycline (tetA), beta-lactam (blaTEM), and quinolone/fluoroquinolone (qnrB and qnrS) were detected. Evolutionary analysis of gyrA gene sequences of human and food animal Salmonella isolates revealed variations but are evolutionarily interconnected. Isolates were grouped into four clades with S. Budapest isolate from cattle clustering with S. Budapest isolated from chicken, whereas S. Essen isolated from sheep and chicken was grouped into a clade. Diverse S. enterica serovars with high antibiotic resistance profile are ubiquitous in food animals; hence, there is a need for surveillance and prudent use of antibiotics in human and veterinary medicine.

Persistent Staphylococcus aureus nasal colonization in ambulatory human immunodeficiency virus-infected patients in Nigeria: Risk factors and molecular features.

This longitudinal study on Staphylococcus aureus colonization in Nigerian human immunodeficiency virus patients (n = 187) found a trend towards a higher proportion of persistent S. aureus carriage in patients with advanced human immunodeficiency virus infection, low CD4+ cell counts, and a predominance of isolates belonging to ST8/spa-CC064 in persistent carriers.

The prevalence and plasmid profile of non-typhoidal salmonellosis in children in Lagos metropolis, South-western Nigeria.

INTRODUCTION: Non-typhoidal Salmonella is the causative agent of gastroenteritis, a food-borne and zoonotic infection which is a major cause of high morbidity and death among children under 5 years of age especially from resource poor settings like the developing countries. METHODS: This study was carried out for 6 months to determine the prevalence and plasmid profile of non-typhoidal salmonellosis in children in Lagos metropolis. A total of 105 stool samples were collected from diarrheal children aged 3 months to 12 years and processed during this period. The isolates were identified using Selenite F Broth, Salmonella-Shigella Agar, Kligler Iron Agar, and Motility-indole-Urea medium, citrate and sugar utilization tests. RESULTS: A total number of 127 isolates were identified, 2 of which are Salmonella enteritidis (1.6%). The non-typhoidal Salmonellae were sensitive to ciprofloxacin, cetotaxime, streptomycin, cotrimxazole and tetracycline. Only one of the 2 isolates (50%) was sensitive to amoxillin and sulphonamide while none of them (0%) was sensitive to cefuroxime. CONCLUSION: The plasmid analysis of the isolates showed that they harboured no detectable plasmids; this suggests that the resistance was chromosomally mediated.

Application of a point-of-care test for the serodiagnosis of typhoid fever in Nigeria and the need for improved diagnostics.

INTRODUCTION: There is an urgent need for affordable point-of-care diagnostics for the differentiation of febrile illnesses and the confirmation of typhoid in endemic countries. METHODOLOGY: Blood samples were collected from febrile patients with clinical suspicion of typhoid and screened for typhoid fever using the Widal and Typhi Dri Dot tests, while stool and blood samples were screened for Salmonella Typhi using the culture method as well as PCR as a confirmatory test. RESULTS: A high proportion of febrile patients from Lagos with clinical suspicion of typhoid fever reacted positively in a simple and rapid latex agglutination assay for typhoid fever, indicating that this illness is a common and presumably under-diagnosed health problem in this metropolis. Seropositivity was 19.2% in the rapid test compared with 22.9% in the classical Widal test. The confirmation of typhoid in these seropositive patients appeared cumbersome because of negative blood cultures and low DNA yield in molecular testing. A review of the literature revealed that in Nigeria seroprevalence rates can be high in the normal population and that pathogens other than S. Typhi are often isolated from the blood of seropositive febrile patients. CONCLUSION: The simplicity and the relatively high specificity (97.8%) of the rapid test as determined in a study performed in Indonesia calls for a further validation of this promising test for use in Africa.