Antibiotic Resistance Profile of Non-Extended Spectrum Beta-Lactamase-producing Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

One of the major challenges facing health professionals is the prevalence of antibiotic resistance. Most Gram-negative bacteria produce beta-lactamases which are enzymes that in-activate ?-lactams. Recent publications suggested that extended spectrum beta-lactamase production in E. coli and K. pneumoniae is one of the main causes of antimicrobial resistance in penicillins, cephalosporins and some non-beta-lactam antibiotics in Accra. This present work sought to determine the resistance profile of antimicrobials to non-ESBL-producing isolates in Accra. The 400 K. pneumoniae and E. coli isolates were screened for non-ESBL-producing strains using the combined disk method. The minimum inhibition concentration for 17 antibiotics was determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France).  Among the 400 total bacterial isolates, 198 (49.5%) were non-ESBL producers. Co-resistances to ampicillin (66.7%), piperacillin (59.1%), tetracycline (77.8%) and trimethoprim/sulphamethoxazole (68.2%) have been collaborated in this work. The increasing rise in resistance to the beta-lactam/beta-lactamase inhibitor combination antibiotics such as amoxicillin/clavulanic acid (13.6%) and piperacillin/tazobactam (18.7%) is problematic since they have become the empirical drug of choice for treating most infections. The steady increase in resistance to gentamicin (17.2%) as well as the floroquinolones such as ciprofloxacin (39.4%) and norfloxacin (34.9%) is alarming. In the absence of ESBLs, cephalosporins generally have been effective in treating infections caused by enterobacteria. Nitrofurantoin remains reliable for managing non-life threatening urinary tract infections. Amikacin and imipenem continue to be effective third-line treatment options for Gram-negative bacteria infections.  As antibiotic resistance increases and the development of new antimicrobials declines, it is imperative that we use antimicrobials that are still effective rationally. Evidence based antibiotic prescriptions and usage as well as regular evaluation of antibiotic resistance will help to control the spread of antibiotic resistance in Accra, Ghana. Keywords: Extended spectrum beta-lactamase, Resistance, Antibioti

Antibiotic Resistance Profile of CTX-M-type Extended-Spectrum Beta-Lactamases in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta lactamases that are capable of hydrolysing beta-lactams except carbapenems and cephamycins. The most common ESBL types include CTX-M, TEM and SHV. This genetic diversity in the various ESBL-producing organisms may reflect characteristic differences in relation to pathogenesis, antibiotic resistance expression, response to therapy, transmission and infection control. This work sought to determine the characteristic antibiotic minimum inhibition concentrations (MICs) and antimicrobial sensitivity profile of CTX-M-type ESBLs in Accra. Hundred (100) DNA templates were extracted from ESBL-producing K. pneumoniae and E. coli isolates. The specific ESBL types were determined by polymerase chain reaction with specific primers and reaction conditions. The MICs of the antibiotics were determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France). The results showed that CTX-M-type ESBL have cefotaxime MIC in the resistant range of >64 µg/ml. The CTX-M-type ß-lactamases showed co-resistances to gentamicin (88.6%), tetracycline (71.4%), trimethoprim-sulphamethoxazole (98.6%).The resistance of CTX-M-type ESBL producing organisms to fluoroquinolones have been well established in this work with resistances in ciprofloxacin (71.4%) and norfloxacin (71.4%) with MIC90 being >4 µg/ml and >16 µg/ml respectively. The beta-lactam-beta-lactamase inhibitor combination of piperacillin-tazobactam was more susceptible to CTX-M-type ESBL than amoxicillin-clavulanate. Imipenem and amikacin has been established as the in vitro drug of choice for the management of organisms producing CTX-M-type ESBL in this present work. Efforts should be made to control the increasing prevalence of CTX-M-type producing organisms in the communities and hospital settings in Accra with their adverse multiple-drug resistance. Keywords: Extended spectrum beta-lactamase, CTX-M-type ESBL, Resistance, Antibiotics

The Reliability of Using Vitek 2 Compact System to Detect Extended-Spectrum Beta-lactamase-producing Isolates in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta-lactamases that are capable of hydrolysing ?-lactams except carbapenems and cephamycins. The global increased prevalence of ESBL-producing bacteria creates an urgent need for laboratory diagnostic methods that will accurately and rapidly identify the presence of ESBL phenotypes in clinical isolates. The Vitek 2 System (bioMérieux, France) is a rapid automated microbiological system used for bacteria and yeast identification, antimicrobial susceptibility testing (AST), resistance mechanism detection and epidemiologic trending and reporting using its advanced expert system. This present work sought to determine the reliability of routinely using Vitek 2 System to accurately and rapidly detect ESBL-producing E. coli and K. pneumoniae in Accra. The ESBL phenotypes for 400 E. coli and K. pneumoniae isolates were determined using the Vitek 2 system and combined disc synergy method. The results were used to determine the sensitivity, specificity, negative predictive value and positive predictive value of the Vitek 2 ESBL test through comparative analysis with the combined disk synergy method which is the reference method recommended by CLSI. The findings of this work indicated that the sensitivity, specificity, positive predictive value and negative predictive value of Vitek 2 system was 98.5%, 98.9%, 99% and 98.5% respectively. Consequently, Vitek 2 system is a reliable semi-automated microbiology system which may be used for routine, accurate and rapid detection of ESBL strains in health facilities in Accra, Ghana. Keywords: Vitek 2 Compact System, Extended spectrum beta-lactamase, bioMérieux, E. coli and K.  pneumoni

Phenotypic Characterization of AmpC beta-lactamase among Cefoxitin Resistant Escherichia coli and Klebsiella pneumoniae Isolates in Accra, Ghana

AmpC ?-lactamases hydrolyze penicillins, cephalosporins and cephamycins and resist inhibition by clavulanate, sulbactam, and tazobactam. Strains with AmpC genes are inherently resistant to multiple agents, making the selection of an effective antibiotic difficult. This present work sought to investigate the occurrence of AmpC beta-lactamases-producing phenotypes in E. coli and K. pneumoniae and their antimicrobial sensitivity profile. Four hundred K. pneumoniae and E. coli non-duplicate isolates were collected and their antibiotic sensitivity testing for cefoxitin and other 16 antibiotics were determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France).  The isolates resistant to cefoxitin were confirmed as AmpC beta-lactamases-producing phenotypes with disk synergy testing (DST) using cefotaxime or ceftazidime with or without boronic acid. An increase in zone diameter of ?5mm in the presence of boronic acid indicates the presence of AmpC beta-lactamases in the test organism. The results showed that of the 50 cefoxitin resistant isolates screened from 400 bacterial isolates, 5(10%) were AmpC beta-lactamase-producers with 60%, 60%, 60%, 80% and 100% multiply antibiotic resistance in gentamicin, ciprofloxacin, norfloxacin, trimethoprim/sulfamethoxazole and tetracycline respectively. Nitrofurantoin which indicated 100% susceptibility with MIC90 of 32µg/ml may be a therapeutic option especially for non-life-threatening urinary tract infection. Imipenem was the antibiotic of choice with 100% susceptibility rates (MIC90 of ?1µg/ml). Though the insignificant (p>0.05) levels of AmpC beta-lactamase phenotypes may not require routine detection in health facilities, there is the need to implement evolutionary antibiotic administration policies and pragmatic infection control measures in the hospitals.      Keywords: AmpC beta-lactamase, Cefoxitin, ?-lactams, E. coli, K. pneumonia

Phenotypic Determination and Antimicrobial Resistance Profile of Extended Spectrum Beta-lactamases in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta lactamases commonly found in the Enterobacteriaceae that are capable of hydrolysing ?-lactams except carbapenems and cephamycins. ESBLs confer resistance to several non-ß-lactam antibiotics. ESBL-producing organisms appear susceptible to cephalosporins in vitro using conventional breakpoints but ineffective in vivo. This work sought to determine the occurrence of ESBL in E. coli and K. pneumoniae and their antibiotic resistance profile. Four hundred K. pneumoniae and E. coli non-duplicate isolates were collected at the Central Laboratory of Korle Bu Teaching Hospital and Advent Clinical Laboratories. They were definitively identified and their minimum inhibition concentration and antibiotic sensitivity testing for 17 antibiotics were determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France).  The isolates were confirmed as ESBL-producing strains using the Combination Disk Synergy Method. The results indicated that 202 (50.5%) of the bacterial isolates were ESBL-producing phenotypes with high resistant to gentamicin, ciprofloxacin, tetracycline and trimethoprim/sulfamethoxazole indicating 82.2%, 79.7%, 70.8% and 97% resistant rates respectively. imipenem and amikacin were the antibiotics of choice with 99% and 94.1% susceptibility rates (MIC90 of ?1µg/ml and 4µg/ml respectively). It is imperative to routinely detect ESBL-phenotypes in health facilities, implement appropriate antibiotic administration policy and infection control measures in the hospitals.   Keywords: Extended Spectrum Beta-lactamase, Antimicrobial Resistance, ?-lactams, K. pneumoniae, E. col

Penicillin resistance in serogroups/serotypes of Streptococcus pneumoniae causing invasive infections in Central Saudi Arabia

Objective: To determine the minimum inhibitory concentrations (MICs) of penicillin, ceftriaxone and vancomycin of serogroups/serotypes of Streptococcus pneumoniae (S. pneumoniae) from invasive diseases in all age groups from major hospitals in Riyadh, Kingdom of Saudi Arabia (KSA). Methods: All isolates of S. pneumoniae from patients with invasive pneumococcal infections between February 2000 and November 2001 were prospectively collected from 8 major hospitals in Riyadh, KSA. The isolates were confirmed as S. pneumoniae at the King Khalid University Hospitals, Riyadh, KSA and then serogrouped/serotyped using the agglutination method. The MICs for penicillin, ceftriaxone and vancomycin were carried out using the E-test. Results: Forty-three percent of the isolates were resistant to penicillin mostly of the intermediate type (97%). The resistant strains were mainly confined to serogroups/ serotypes 6, 23, 19 and 15 and the 7-valent conjugate vaccine covers 76% of the penicillin-resistant strains. Only one isolate was resistant to ceftriaxone. Conclusion: In view of the rather insignificant level of highly resistant-penicillin strains and the virtual absence of resistance to ceftriaxone we would like to suggest using ceftriaxone for treating invasive pneumococcal infections outside the central nervous system. We recommend that the conjugate vaccine would be a useful adjunct to penicillin prophylaxis in patients at risk in our community.Corresponding Author: Dr. Kingsley Twum-Danso, Associate Professor & Consultant of Microbiologist, College of Medicine (32), King Saud University, PO Box 2925, Riyadh 11461, Kingdom of Saudi Arabia. Email: [email protected]