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Aim: To determine the prevalence and genotypic characterisation of extended spectrum beta-lactamases produced by gram negative bacilli isolated at Mbarara Regional Referral Hospital (MRRH). Samples: Gram negative clinical isolates. Study Design: Laboratory-based descriptive cross-sectional study. Place and Duration of the Study: MRRH, June and August 2012. Methods: Gram negative clinical isolates were sub cultured, and identified using biochemical tests. They were screened for ESBL by using oxyimino-cephalosporins and confirmed by double disc synergy Genotyping was performed using the PCR for TEM, SHV and CTX-M. Susceptibility pattern for the extended spectrum beta-lactamases, (ESBL) - positive isolates to other antibiotic classes was performed by the Kirby Bauer Technique. Results: A total of 484 isolates were included in the study. The commonest ESBL producers were Escherichia coli (34%), followed by unidentified coliforms (19.3%) and Klebsiella spp. (12.7%). Phenotypically, 88/484 were ESBL producers while genotypically 213/ 484 possessed ESBL genes. The ESBL genes were blaCTX-M (146; 70%), blaSHV (72; 34%) and blaTEM (100; 47%). 87of 213 isolates expressed more than one ESBL gene. Of these 36 (7.4%) produced blaCTX-M/blaSHV, 28 (5.8%) blaCTX-M /blaTEM, 4 (0.8%) blaSHV/ blaTEM and 19 (3.9%) blaCTX-M/blaSHV/blaTEM. Sixty two (16%) were phenotypically and genotypically positive, 12 (3%) of the isolates were phenotypically positive but genotypically negative and 140 (37%) isolates were phenotypically negative but genotypically positive. The ESBL producers were highly susceptible to imipenem (95%), nitrofurantoin (66%) but less susceptible to ampicillin (4%) and ticarcillin (7%). Conclusion: ESBL production among the Gram-negative clinical isolates at MRRH is very high with several isolates possessing multiple genes. The ESBL producers are highly susceptible to imipenem, but very resistant to ciprofloxacin.
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Aims: The study was conducted to determine the prevalence of Clindamycin (CL) resistance and antimicrobial susceptibility among clinical isolates of Staphylococcus aureus (S. aureus) from Mbarara Regional Referral Hospital (MRRH) in Southwestern Uganda. Study Design: Laboratory based cross sectional study. Place and Duration of the Study: The study was conducted at the Microbiology department of Mbarara Regional referral hospital between November 2012 and December 2013. Methodology: In our study, we recruited 300 S. aureus isolates that were stored in the laboratory and were obtained from different clinical samples. The isolates were tested for antimicrobial susceptibility by phenotypic methods and for the genotypic expression of Macrolide Lincosamide StreptograminB (MLSB) resistance genes (ermA, ermB, ermC, and msrA). The D-test was also performed. Results: Phenotypically, a total of 109 (36%) S. aureus isolates were resistant to CL, of which 9 (3%) were constitutively resistant while 100 (33.3%) were inducibly resistant. Genotypicaly, 134/300 (44.7%) isolates possessed at least one of the MLSB resistance genes. 23/300 (7.7%) tested positive for ermB, 98/300 (32.7%) tested positive for the ermC and 43/300 (14.3%) tested positive for the msrA genes with none possessing the ermA gene. Isolates were highly resistant to Sulfamethoxazole/trimethoprim, Erythromycin and Oxacillin with moderate resistance to Vancomycin and Imipenem and least resistance to Linezolid Conclusion: S. aureus resistance to CL was high in this set up. There was also high resistance to Sulfamethoxazole/trimethoprim, Erythromycin and Oxacillin but low resistance to Linezolid.
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Aim: To determine the prevalence and antibiotic susceptibility patterns of clinical isolates of methicillin resistant Staphylococcus aureus isolated at Mbarara Regional Referral Hospital. Method: A total of 400 S. aureus isolates recovered from various clinical specimens at Mbarara Regional Referral Hospital were included in this study. Phenotypic screening was performed using Oxacillin. Presence of mecA gene was studied using polymerase chain reaction (PCR). The mecA positive isolates were tested for susceptibility to, Vancomycin, Imipenem, Fusidic acid, Trimethoprim/Sulfamethoxazole, Clindamycin and Linezolid using the Kirby Bauer technique. Results: Of the 300 isolates of S. aureus 31.3% (94) were phenotypically MRSA and 38% (114) had the mecA gene. All the MRSA isolates were susceptible to vancomycin and linezolid but were highly resistant to trimethoprim/sulfamethoxazole (70.2%). Of the 114 MRSA isolates 19.3% (22) were multi-drug resistant S. aureus (MDR-MRSA). The study found that there was a significant difference between genotypic and phenotypic detection methods (p < 0.001). Conclusion: The prevalence of MRSA in Mbarara is high (38%) with a high resistance to trimethoprim/sulfamethoxazole. The detection of mecA gene is a good predictor of methicillin resistance in S. aureus. There is a worrying prevalence of MDR MRSA among the clinical isolates of S. aureus in South Western Uganda.
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Aim: To characterize AmpC-beta lactamases among Enterobacteriaceae isolates from clinical samples at Mbarara Regional Referral Hospital. Study Design: Laboratory-based descriptive cross-sectional study Place and Duration of Study: Microbiology Department, Mbarara Regional Hospital and MBN clinical Laboratories, between May to September 2013. Methodology: This study included 293 Enterobacteriaceae isolates recovered from clinical specimens that included blood, urine, stool and aspirates. AmpC Beta lactamase production was determined using disc placement method for cefoxitin at a break point of <18mm. Common AmpC plasmid mediated genes were EBC, ACC, FOX, DHA, CIT and MOX were; was determined by Multiplex PCR as described by Hanson and Perez-Perez. Results: Plasmid mediated AmpC phenotype was confirmed in 107 of the 293 (36.5%) cefoxitin resistant isolates with 30 isolates having more than one gene coding for resistance. The commonest source that harbored AmpC beta lactamases was urine and E. coli was the most common AmpC producer (59.5%). The genotypes detected in this study, included EBC (n=36), FOX (n=18), ACC (n=11), CIT (n=10), DHA (n=07) and MOX (n=1). Conclusion: Our findings showed that prevalence of AmpC beta- lactamase at MRRH was high (39.6), with EBC as the commonest genotype among Enterobacteriaceae Urine and E. coli were the commonest source and organism respectively that harbored AmpC beta-lactamases. There‘s rational antimicrobial therapy and antibiotic susceptibility tests should be requested by health workers especially patients presenting with urinary tract infections and bacteraemias.
ABSTRACT
Introduction: Staphylococcus epidermidis is often considered a non-pathogenic organism but it causes nosocomial infections. To distinguish invasive strains; comparative studies of patient and community isolates may offer some clues. We investigated the distribution of virulence determinants in patient isolates from Uganda. Methodology: S. epidermidis isolates were identified with the Staph API ID 32 kit. Antimicrobial susceptibility; biofilm formation and hemolysis were detected with standard procedures. Genes associated with virulence (aap; atlE; bhp; hla; hld; ica; IS256; sdrE; sea; tsst) and antimicrobial resistance (aac(6')-Ie-aph(2'')-Ia; aph(3')-IIIa; ant(4')-Ia; blaZ; mecA; vanA/vanB1) were detected by PCR. Results: S. epidermidis grew in 30 (30/50; 60) ICU samples and 20 (20/60; 33) community samples (one isolate per sample per patient/person). All ICU isolates (30/30; 100) were IS256 and hld positive; 22 (22/30; 73) were biofilm/ica positive; 21 (21/30; 70) were hemolytic on blood agar; nine (9/30; 30) contained atlE gene; six (6/30; 20) hla gene; five (5/30; 17) aap gene; and three (3/30; 10) bhp gene. A gene encoding an aminoglycoside-modifying enzyme; aph(3')-IIIa; was highly prevalent (28/30; 93); while blaZ (2/30; 7); mecA (3/30; 10); vanA (3/30; 10) and vanB1 (3/30; 10) were less prevalent. Of the community isolates; one (1/20; 5) was ica positive; two (2/20; 10) formed biofilms; and three (3/20; 15) possessed the atlE gene. bhp; aap; IS256; hld and antimicrobial resistance genes were not detected in community isolates. Conclusions: S. epidermidis from ICU patients in Mulago Hospital is potentially virulent and could be a reservoir for antimicrobial resistant genes