Genotypic Determination of Extended Spectrum ß-Lactamases and Carbapenemase Production in Clinical Isolates of Klebsiella pneumoniae in Southwest Nigeria.

INTRODUCTION: Klebsiella pneumoniae is a major pathogen implicated in healthcare-associated infections. Extended-spectrum ß-lactamase (ESBL) and carbapenemase-producing K. pneumoniae isolates are a public health concern. This study investigated the existence of some ESBL and carbapenemase genes among clinical isolates of K. pneumoniae in Southwest Nigeria and additionally determined their circulating clones. MATERIALS AND METHODS: Various clinical samples from 420 patients from seven tertiary hospitals within Southwestern Nigeria were processed between February 2018 and July 2019. These samples were cultured on blood agar and MacConkey agar, and the isolated bacteria were identified by Microbact GNB 12E. All K. pneumoniae were confirmed by polymerase chain reaction (PCR) using the 16s rRNA gene. Antibiotic susceptibility testing (AST) was done on these isolates, and the PCR was used to evaluate the common ESBL-encoding genes and carbapenem resistance genes. Genotyping was performed using multi-locus sequencing typing (MLST). RESULTS: The overall prevalence of K. pneumoniae in Southwestern Nigeria was 30.5%. The AST revealed high resistance rates to tetracyclines (67.2%), oxacillin (61.7%), ampicillin (60.2%), ciprofloxacin (58.6%), chloramphenicol (56.3%), and lowest resistance to meropenem (43.0%). All isolates were susceptible to polymyxin B. The most prevalent ESBL gene was the TEM gene (47.7%), followed by CTX-M (43.8%), SHV (39.8%), OXA (27.3%), CTX-M-15 (19.5%), CTX-M-2 (11.1%), and CTX-M-9 (10.9%). Among the carbapenemase genes studied, the VIM gene (43.0%) was most detected, followed by OXA-48 (28.9%), IMP (22.7%), NDM (17.2%), KPC (13.3%), CMY (11.7%), and FOX (9.4%). GIM and SPM genes were not detected. MLST identified six different sequence types (STs) in this study. The most dominant ST was ST307 (50%, 5/10), while ST258, ST11, ST147, ST15, and ST321 had (10%, 1/10) each. CONCLUSION: High antimicrobial resistance in K. pneumoniae is a clear and present danger for managing infections in Nigeria. Additionally, the dominance of a successful international ST307 clone highlights the importance of ensuring that genomic surveillance remains a priority in the hospital environment in Nigeria.

HIV P24 antigen among HIV antibody seronegative blood donors in Osogbo Osun State, South Western Nigeria.

BACKGROUND: Efforts to curb the spread of HIV transmission through transfusion of blood and its products is still a problem because of challenge in countries using antibody-based rapid methods to detect infection during window period. Transmission of HIV through infected blood and its products accounts for approximately 10% in African region. METHODS: This study analyzed true negativity of HIV infection in blood donors screened by ELISA test based on p24 core antigen detection. Four hundred and eighty (480) blood donors initially negative for HIV antibody by rapid screening kit, Determine™ HIV-1/2 (Abbott Laboratory, IL, USA) and re-screened with Immuno Comb® II HIV 1 and 2 (Bispot kit PBS Organics and Israel 2005). The samples were further tested for the presence of HIV antibody and p24 HIV core antigen using ELISA kits (Genscreen TM ULTRA HIV Ag-Ab) following manufacturer's instructions. All donors initially tested negative for Hepatitis B virus, Hepatitis C virus. RESULT: Two (0.42%) of 480 blood donors tested positive for the p24 HIV core antigen. The two positive donors for the p24 antigen had multiple sexual partners and recent sexually transmitted infections. CONCLUSION: The association of the HIV p24 antigen with blood donation was highly significant (p = 0.000) and pose a great risk to recipients if screening of blood donor is only carried out by HIV antibody detection.

Genotypes and phenotypes of Shiga toxin-producing Escherichia coli (STEC) in Abeokuta, Southwestern Nigeria.

PURPOSE: To characterize the prevalence of hemolytic Shiga toxin-producing Escherichia coli (STEC) with a multidrug-resistant pattern in different age groups in Abeokuta, Nigeria. METHODS: Nonrepetitive E. coli isolates were collected from 202 subjects with or without evidence of diarrhea. Each isolate was biochemically identified and antimicrobial susceptibility testing was performed using the disk diffusion method. A sorbitol fermentation test of all the E. coli isolates was done and the minimum inhibitory concentration of suspected STEC was measured by the standard broth microdilution method to determine antibiotic resistance. The genotypes of stx1, stx2, and hlyA were determined by polymerase chain reaction assay. RESULTS: The majority of subjects were aged ≥40 years (41.6%) and were female (61.9%). Of the 202 subjects, 86.1% had STEC isolates (P<0.05). A high rate of STEC isolates resistant to amoxicillin (90.6%), cefotaxime (77.7%), and cefuroxime (75.7%) was observed. Resistance to amoxicillin, gentamicin, and cefotaxime was demonstrated with a minimum inhibitory concentration >16 µg/mL in 13.9%, 11.4%, and 10.4% of the isolates, respectively. The prevalence of stx1, stx2, and hlyA was 13.9%, 6.9%, and 2.0%, respectively; 5.5% of stx1 were in the 0-10-year-old age group, 3.5% of stx2 were aged ≥40 and above, and 1.0% of the hlyA isolates were in the 0-10-year-old age group. CONCLUSION: The prevalence of virulent STEC is a public health concern. The use of polymerase chain reaction assay should aid quick detection of this virulent serotype and help curb the severe epidemic of human diseases associated with STEC infections.