Salmonellosis in Lagos, Nigeria: Incidence of Plasmodium falciparum-associated Co-infection, Patterns of Antimicrobial Resistance, and Emergence of Reduced Susceptibility to Fluoroquinolones

The present study was undertaken to examine the status of antimicrobial resistance in Salmonella-associated diseases, by verifying possible emergence of reduced susceptibility to fluoroquinolones in Salmonella isolates and determining the incidence of Plasmodium falciparum-associated co-infection with Salmonella serotypes. Antimicrobial resistance in clinical isolates of Salmonellae was examined for a 12-month period. Four hundred and forty-one patients comprising two groups were recruited. Group A comprised 235 patients diagnosed by clinicians of having pyrexia, and group B included stool samples of 206 patients presenting with gastroenteritis. Samples were cultured and isolates identified, and drug susceptibility testing was performed using the standard methods. Of the 235 samples screened in group A, 42 Salmonella isolates and 107 Plasmodium spp. were identified. Of the 42 Salmonella isolates, 19 (45.2%) were Salmonella Typhi, 9 (21.4%) S. Enteritidis, and 7 (16.7%) each of S. Paratyphi and S. Arizonae. Plasmodium spp.-associated co-infection with Salmonellae was observed in 16 patients mostly in complicated typhoidal cases and S. Enteritidis-associated bacteraemia. Fiftty-three of the 206 stool samples from group B patients were confirmed positive for bacterial pathogens, made up of 35 Salmonella and 18 Shigella isolates. Of the Salmonella isolates, 18 (51.4%) were S. Enteritidis, 11 (31.4%) S. Arizonae, 4 (11.4%) S. Paratyphi, and 2 (5.7%) S. Typhi. There was no statistically significant difference (p<0.01) in antimicrobial resistance patterns exhibited among typhoidal Salmonellae isolated in 2000 and 2005. A similar trend in resistance was recorded for non-typhoidal Salmonellae (p<0.05). For the first time in Lagos, Nigeria, Salmonella isolates (10–18%) with reduced susceptibility to both ciprofloxacin and ofloxacin at MIC50 and MIC90 values of 0.015 and 0.03 μg/mL respectively were found. Despite this development, ciprofloxacin and ofloxacin remain the drug of choice for severe cases of salmonellosis, although caution should be exercised by clinicians in their pres-criptions such that fluoroquinolone antibiotic therapy is used only in laboratory-proven cases of typhoid fever and Salmonella-associated bacteraemia to preserve its efficacy

Salmonellosis in Lagos, Nigeria: Incidence of Plasmodium falciparum -associated Co-infection, Patterns of Antimicrobial Resistance, and Emergence of Reduced Susceptibility to Fluoroquinolones

The present study was undertaken to examine the status of antimicrobial resistance in Salmonella-associated diseases, by verifying possible emergence of reduced susceptibility to fluoroquinolones in Salmonella isolates and determining the incidence of Plasmodium falciparum -associated co-infection with Salmonella serotypes. Antimicrobial resistance in clinical isolates of Salmonellae was examined for a 12-month period. Four hundred and forty-one patients comprising two groups were recruited. Group A comprised 235 patients diagnosed by clinicians of having pyrexia, and group B included stool samples of 206 patients presenting with gastroenteritis. Samples were cultured and isolates identified, and drug susceptibility testing was performed using the standard methods. Of the 235 samples screened in group A, 42 Salmonella isolates and 107 Plasmodium spp. were identified. Of the 42 Salmonella isolates, 19 (45.2%) were Salmonella Typhi, 9 (21.4%) S. Enteritidis, and 7 (16.7%) each of S. Paratyphi and S. Arizonae. Plasmodium spp.-associated co-infection with Salmonellae was observed in 16 patients mostly in complicated typhoidal cases and S. Enteritidis-associated bacteraemia. Fiftty-three of the 206 stool samples from group B patients were confirmed positive for bacterial pathogens, made up of 35 Salmonella and 18 Shigella isolates. Of the Salmonella isolates, 18 (51.4%) were S. Enteritidis, 11 (31.4%) S. Arizonae, 4 (11.4%) S. Paratyphi, and 2 (5.7%) S. Typhi. There was no statistically significant difference (p&lt;0.01) in antimicrobial resistance patterns exhibited among typhoidal Salmonellae isolated in 2000 and 2005. A similar trend in resistance was recorded for non-typhoidal Salmonellae (p&lt;0.05). For the first time in Lagos, Nigeria, Salmonella isolates (10-18%) with reduced susceptibility to both ciprofloxacin and ofloxacin at MIC50 and MIC90 values of 0.015 and 0.03 \ub5g/mL respectively were found. Despite this development, ciprofloxacin and ofloxacin remain the drug of choice for severe cases of salmonellosis, although caution should be exercised by clinicians in their prescriptions such that fluoroquinolone antibiotic therapy is used only in laboratory-proven cases of typhoid fever and Salmonella-associated bacteraemia to preserve its efficacy

Staphylococcal bacteraemia among human immunodeficiency virus positive patients at a screening center in Lagos, Nigeria

Bacteraemia due to Staphylococcus aureus in Human immunodeficiency virus (HIV) – positive patients is associated with increased mortality rate. The present study aimed at determining the species distribution and occurrence of staphylococcal bacteraemia in HIV – positive patients in Lagos, Nigeria. Staphylococcal blood stream infection in febrile HIV patients was investigated by culture technique. The antibiotic resistance pattern was investigated using the disk diffusion and methicillin resistance was confirmed by the salt agar methods. The genetic relatedness of S. aureus was determined using Pulsed Field Gel Electrophoresis (PFGE). Eighty-six patients comprising 47 (55%) female and 39 (45%) male, median aged 34 years took part in the study. Staphylococci were identified in 16 (18.6%) patients; 13 (15.1%) and 3 (3.5%) with single and dual Staphylococcus species respectively. The isolates consisted of S. aureus (7 patients), followed by S. haemolyticus (4 patients). Of the thirteen (13) antibiotics tested, isolates were resistant to ampicillin (AMP; 89.5%), tetracycline (TET; 68.4%), cloxacillin (CXC; 89.5%), oxacillin (OXA; 68.4%); chloramphenicol (CHL; 57.9%) and trimethoprim-sulphamethoxazole (SXT; 63.1%). The overall percentage of all the isolates resistant to gentamicin, erythromycin and amoxicillin-clavulanic acid was less than 50%. All the isolates were susceptible to ciprofloxacin and vancomycin and none was positive for methicillin resistance except a strain of S. haemolyticus. Significant genetic diversity was observed among the S. aureus isolates with a predominant pulsotype A. The two isolates with pulsotype A had identical resistotype (AMP, ERY, TET, CXC, SXT). Other PFGE patterns were represented by single isolates except pulsotype C which had a subtype. In these patients, the most frequent Staphylococcus species isolated was S. aureus and the results revealed that clonal dissemination of a virulent pulsotype of S. aureus among this population is plausible and should be a cause for concern