ABSTRACT
Objective: Infections of the urinary tract remains one of the most common bacterial infections with many implicated organisms being Gram-negative, which are increasingly resistant to antimicrobial agents. The aim of the study was to evaluate the resistance of ESBL producing Gram-negative enterobacteriaceae to commonly prescribed antibiotics and the prevalence of CTX-M genes from these isolates using polymerase chain reaction (PCR). Methods: The isolates were collected from urine over a period of 4 mo and studied, and were identified using Microgen Identification Kit (GN-ID). Susceptibility testing was performed by the modified Kirby Bauer disc diffusion method, and results were interpreted according to Clinical and Laboratory Standard Institute (CLSI). Extended-Spectrum Beta-Lactamase (ESBL) production was detected by the double-disc synergy test (DDST). Molecular characterization was based on the isolates that were positive for the phenotypic detection of ESBL. Results: Sixty one (61) isolates of Gram-negative uropathogens were identified. Of these, 19 (31.2%) were E. coli, 15 (24.6%) were Salmonella arizonae, Klebsiella pneumoniae were 7 (11.5%), Klebsiella oxytoca were 3 (4.9%), Enterobacter gergoviae were 6 (9.8%), 4 (6.6%) were Citrobacter freundii, 4 (6.6%) were Serratia marscence, and 1 (1.6%) were Enterobacter aerogenes, Proteus mirabilis, and Edwardsiella tarda each. Analysis of the bacterial susceptibility to antibiotics revealed most of them to be generally resistant to cotrimoxazole (73.3%), nalidixic acid (66.7%), norfloxacin (53.5%), ciprofloxacin (50.5%), gentamicin (48.6%), amoxicillin/clavulanate (45%), and the least resistant was displayed in nitrofurantoin (30%). Of the 15 ESBL producers, 11 (73.3%) were harbouring bla CTX-M genes. Conclusion: The study revealed a high susceptibility to nitrofurantoin, whereas susceptibility to cotrimoxazole was lowest. It further portrays a high prevalence of enterobacteriaceae isolates harbouring bla CTX-M genes in Sokoto metropolis.
ABSTRACT
Staphylococcal isolates from specimen submitted to the Medical Microbiology laboratory of Ahmadu Bello University Teaching Hospital, Zaria were collected over a period of 6 months (February-July 2012), characterized by microbiological standard procedures and the S. aureus small colony variant (SCV) isolates were isolated. The antibiotic susceptibility pattern of the isolates was determined by the Kirby-Bauer-CLSI modified disc agar diffusion (DAD) technique. The SCV isolates were assessed for the carriage of four virulence genes; sdrE (putative adhesin) icaA (intracellular adhesin) hlg (hemolysin), Cna (collagen adhesin). A total of 258 non-duplicate staphylococcal isolates made up of 219 (84%) S. aureus and 39 (15%) coagulase-negative staphylococci (coNS) where obtained. A total of 48 (22%) isolates were determined to be S. aureus SCV mainly from wound/abscess (31%). S. aureus SCV isolates were generally resistant to all the nine antibiotics tested with only minimal sensitivity to tigecyclin (10.4%) and ciprofloxacin (18.8%). Statistically, there was no significant difference between the microbial load and the different antibiotics that were used, (P ≥0.05). None of the S. aureus SCV isolates carried the four virulence genes which were tested in this study. The results have therefore proved that S. aureus small colony variant exist in our environment and they are more resistant to most antimicrobial agent than their wild type.
ABSTRACT
Aims: To study the susceptibility profile of methicillin-resistant Staphylococcus aureus (MRSA) isolates from orthopaedic patients to antibiotics and methanolic extracts of Parkia biglobosa. Background: Antimicrobial resistance in Staphylococcus aureus has attained alarming proportions worldwide; with methicillin resistant Staphylococcus aureus (MRSA) becoming a major pathogen of public health importance associated with community and hospital acquired infections. Wound infections in orthopaedic patients with multidrug resistant pathogens significantly delay or prevent the union of fractured bones. The increasing prevalence of multidrug resistance in Staphylococcus aureus isolates calls for the search for alternative anti-staphylococcal agents. Methodology: Suspected staphylococcal isolates from wound, skin and bed swab samples from orthopaedic patients in a tertiary hospital in Zaria, Nigeria were characterized by established microbiological procedures and their antibiotic susceptibility pattern determined by the Kirby-Bauer-CLSI modified disc agar diffusion (DAD) technique. The activity of crude methanolic extract of the root, stem bark and leaf of Parkia biglobosa on the isolates determined. Results: A total of 179 isolates were confirmed S. aureus: wounds (24.6%), skin (39.1%) and bed (36.3%). The isolation rates for MRSA from the various sites were: wound (75%), skin (51.4%) and bed (73.8%). Antibiotic susceptibility testing revealed that the isolates were generally resistant to ampicillin (100% for all sites); ceftriazone (wound 69.7%, skin 72.2%, bed 70.8%); gentamicin (wound 54.5%, skin 52.8%, bed 37.5%) and ciprofloxacin (wound 51.5%, skin 47.2%, bed 35.4%). The phytochemical screening of the methanolic extract of the leaf, root and stem bark of Parkia biglobosa showed the presence of saponin, tannin, flavonoids and cardiac glycosides. The stem bark of Parkia biglobosa showed the greatest activity against all the multidrug resistant MRSA isolates at the 10mg/ml-25mg/ml concentration range used. In the search for alternative antistaphylococcal agents from natural sources, Parkia biglobosa will be a possible candidate for further investigation. Conclusion: There was high prevalence of multidrug resistant Staphylococcus aureus isolates from the clinical and surveillance samples from the orthopaedic patients.
ABSTRACT
Aims: To carry out the antistaphylococcal activity of n-butanol and aqueous sub-fractions of Alchornea cordifolia (Schumach. And Thonn.) Müll. Arg. leaf extract against multidrug resistant Staphylococcus aureus. Study Design: Characterization and antibiotic susceptibility determination of the test S. aureus isolates, extraction of A. cordifolia leaf, partitioning of the extract, Zones of inhibition and Minimum Inhibitory and Bactericidal Concentrations determination. Place and Duration of Study: Department of Pharmaceutics and Pharmaceutical Microbiology, Ahmadu Bello University, Zaria, Nigeria. February 2010 to October 2011. Methodology: A. cordifolia leaves were collected from Abuja, Nigeria. The activity of the ethanol extract, N-butanol (NSF) and aqueous (ASF) sub-fractions of the plant leaf against five clinical staphylococcal isolates and the standard Methicillin Resistant S. aureus (MRSA) ATCC 33591 were determined using agar-well diffusion and broth dilution methods. The antibiotic susceptibility pattern of the isolates was determined by the Kirby- Bauer-CLSI modified disc agar diffusion technique (DAD). Results: The diameter zones of inhibition showed by ethanol extract against the test staphylococcal isolates ranged between 12 mm - 26 mm, while the diameter zones of inhibition observed from N-butanol sub-fraction and aqueous sub-fraction against the isolates were between 11 mm - 36.5 mm and 11 mm - 35 mm respectively. The diameter zones of inhibition of the sub-fractions against the standard MRSA ATCC 33591 ranged from 11 mm – 27.5 mm. The diameter zones of inhibition of the test antibiotics ranged from 10 mm to 23 mm. The Minimum Inhibitory Concentration (M. I. C.) and Minimum Bactericidal Concentration (M. B. C.) values produced by ethanol extract were higher than those of the sub-fractions. N-butanol sub-fraction produced the lowest M. I. C and M. B. C. values of 0.625 mg/ml – 1.25 mg/ml and 1.25 mg/ml – 2.5 mg/ml respectively. The M. I. C. and M. B. C. values of the N-butanol sub-fraction against the standard strain ATCC 33591 were 1.25 mg/ml and 2.5 mg/ml respectively. Conclusion: The tested N-butanol and aqueous sub-fractions of A. cordifolia leaf were active against the S. aureus strains at low concentrations. The plant can be a possible candidate in the search for alternative antistaphylococcal agents.