Research Article
Volume 1 Issue 1 - 2015
Prevalence and Characterization of Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae in Brack-Alshati, Fezzan, Libya
Aisha M Shahlol1, Omar M Abukhres1 and Ibrahim A Taher2*
1Department of Medical Laboratory Technology, Sabha University, Libya
2Department of Pathology, Aljouf University, Kingdom of Saudi Arabia
*Corresponding Author: Ibrahim A Taher, Department of Pathology, College of Medicine, Aljouf University, Sakaka, Kingdom of Saudi Arabia.
Received: December 9, 2014; Published: January 31, 2015
Citation: Ibrahim A Taher., et al. “Prevalence and Characterization of Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae in Brack-Alshati, Fezzan, Libya”. EC Microbiology 1.1 (2015): 23-32.
Background: Extended spectrum β-lactamase ESBL-producing Enterobacteriaceae are increasing worldwide. However, there is sparse data on their prevalence and nature in Libya. A prospective study was performed to:
  1. Assess the prevalence of ESBL-producing Enterobacteriaceae among gastrointestinal and urinary tract infection patients and healthy individuals, and
  2. Determine the antibiotics sensitivity profiles and β-lactamase production of the isolates.
Methods: 307 individuals were voluntarily enrolled in this study; 201 patients and 106 healthy individuals. 106 stool samples were collected from the healthy group and 80 stool and 121 urine samples were from patients. Enterobacteriaceae isolates were tested for ESBL production by the double disk synergy test, and antibiotic susceptibility testing was performed using the disk diffusion method.
Results: Of the total of 333 bacterial isolates, 208 were from patients and 125 from the healthy group. Patients yielded 149 E. coli (71.6%), 35 Klebsiella pneumoniae (16.8%), 6 Klebsiella oxytoca (2.9%), 6 Proteus mirabilis (2.9%), 5 Enterobacter cloacae (2.4%), 4 Citrobacter freundii (1.9%), 2 Enterobacter agglomerans (0.96%) and 1 Salmonella typhi (0.48%). On the other hand, 91 E. coli (72.8%), 24 K. pneumoniae (19.2%), 5 Ent. cloacae (4%) and C. freundii (4%) isolates were from the healthy group. In total, only 15 isolates (4.5%) produced ESBL of which, 12 (5.7%) were from patients and 3 (2.4%) from the healthy group. 8 out of 149 (5.36%) E. coli, and 4 out of 35 (11.4%) K. pneumoniae produced ESBLs from patients’ isolates compared to a single E. coli (1.09%) and 2 K. pneumoniae (8.3%) from the healthy group isolates.
Conclusions: The prevalence of ESBL-producing Enterobacteriaceae strains was 4.5% among isolates from healthy and patients stool and urine samples in the targeted area in Libya. ESBL strains were more prevalent in patients’ samples (5.7%) than healthy controls (2.4%). Their antibiotic sensitivity profile showed more resistance in patients’ isolates than the healthy volunteers.
Keywords: Extended β-lactamase-producing; Enterobacteriaceae; E. coli; K. Pneumoniae; Antibiotic resistance; Libya
Abbreviations: AML: Ampicillin; AMP: Amoxicillin; TIC: Ticarcillin; KF: Cephalothin; FOX: Cefoxitin; CFP: Cefoperazone; CTX: Cefotaxime; CAZ: Ceftazidime; CRO: Ceftriaxone; IPM: Imipenem; ATM: Aztreonam; TZP: Piperacillin/Tazobactam; AMC: Amoxicillin/Clavulanic acid (augmentin); CIP: Ciprofloxacin; NA: Nalidixic acid; F30: Nitrofurantion; C30: Chloramphenicol; TE: Tetracycline; SXT: Trimethoprim/Sulfamethoxazole; CN: Gentamicin
The increase in antimicrobial resistance of pathogenic bacteria is a major problem worldwide. Extended spectrum β-lactamases (ESBLs) are plasmid-encoded enzymes that are produced most often by Klebsiella and E. coli species. ESBLs are the most important factor contributing to Gram negative bacilli resistance to broad-spectrum β-lactam antibiotics such as cefotaxime, ceftriaxone, ceftazidime, aztreonam and cefpodoxime [1]. These β-lactamases are easily transferable among bacterial species. They are mostly of the KPC, VIM, IMP, NDM, and OXA-48 types. Their current extensive spread worldwide in Enterobacteriaceae is of great importance and concern. Infections caused by these bacteria have limited treatment options and have been associated with high mortality rates. The prevalence of carbapenemases in the Mediterranean region is particularly high constituting one of the most important reservoirs [2]. The first ESBL was reported in Klebsiella pneumoniae in 1983 [3]. The majority of ESBLs isolated from clinical samples have been SHV or TEM types of TEM-1, and 2, and SHV-1 [4]. More than 40 of these extended spectrum enzymes (named TEM-1, -2, -3 and SHV-1, -2, etc) have been discovered since [4]. These ESBLs have enhanced stability in the presence of β-lactam antibiotics and are positively selected through point mutations in the TEM and SHV β-lactamase genes [5,6]. In recent years, β-lactamases that hydrolyze carbapenems have also been discovered, such as; the Klebsiella pneumoniae carbapenemase (KPC) and metallo-β-lactamases (MBLs), such as the New Delhi metallo-β-lactamase (NDM) [7,8].
ESBL-producing Enterobacteriaceae have been responsible for numerous outbreaks of infections throughout the world and pose challenging infection control measures [9]. Urinary tract and blood stream infections are some examples. Intravascular and urinary catheters, emergency intraabdominal surgery, gastrostomy or jejunostomy tube, gastrointestinal colonization, length of hospital or intensive care unit stay, prior antibiotics, prior nursing home stay, severity of illness, and ventilator assistance are some risk factors for acquiring an infection with ESBL producing strains [10,11]. The frequency of ESBL-producing bacteria differs significantly by population geographic location [12-15].
Although the study of ESBL-producing Enterobacteriaceae in Libya was previously attempted [16,17], however, none has attempted to investigated samples from rural areas. Therefore, the goal of this study was to investigate the prevalence of ESBL-producing Enterobacteriaceae among gastrointestinal and urinary tract infection patients and healthy individuals in the southern Brack-Alshati area, Fezzan, Libya. Their antibiotic sensitivity profile to a panel of antibiotics employing double disk synergy and disk diffusion test, and β-lactamase production along with other isolates was determined.
Materials and Methods
This study voluntarily enrolled 307 individuals comprising 201 patients-aging 7 months to 95 years attending Brack General Hospital and other private clinics in this area and 106 healthy controls aging 19 to 36 years. The samples were collected in the period from October 2010 to April 2011. The male to female ratio was 1 : 2 among patients and controls. Healthy controls provided 106 stool samples and 80 stools and 121 urine samples were collected from the patients. An informed consent was obtained from all participants or their custodians prior the participant enrollment and the study was approved by our local committee for Medical and Research Ethics.
All samples were inoculated onto MacConkey agar plates (Mast Diagnostic, Mast Group LTD, Merseyside, UK). Additionally, the stool samples were inoculated onto Xylose Lysine Deoxycholate (XLD; Oxoid Limited, Hants, England). All plates were incubated at 37°C for 24 hours in air. The suspected colonies were streaked onto fresh MacConkey agar plates for purity and later identified using standard microbiological methods-Gram staining, oxidase test, IMVIC and carbohydrate fermentation tests. Isolates identified as Enterobacteriaceae were finally preserved on nutrient agar slants in individual screw capped bottles at 4°C.
The antibiotic susceptibility testing was performed using the disk diffusion method according to the Clinical Laboratory Standards Institute (CLSI) guidelines [18]. E. coli ATCC 25922 was used as a control. Commercially available antibiotic discs (Oxoid Limited, Basingstoke, Hampshire, England) were used for antibiotics susceptibility testing including that included Ampicillin (AML, 10 µg), Amoxicillin (AMP, 10 µg), Ticarcillin (TIC, 75 µg), Amoxicillin/Clavulanic acid (Augmentin) (AMC, 20/10 µg), Piperacillin/Tazobactam (TZP, 100/10 µg), Cephalothin (KF, 30 µg), Cefoperazone (CFP, 5 µg), Cefoxitin (FOX, 30 µg), Cefotaxime (CTX, 30 µg), Ceftriaxone (CRO, 30 µg), Ceftazidime (CAZ, 30 µg), Imipenem (IPM, 30 µg), Aztreonam (ATM, 30 µg), Gentamicin (CN, 10 µg), Tetracycline (TE, 30 µg), Ciprofloxacin (CIP, 5 µg), Nalidixic acid (NA, 30 µg), Chloramphenicol (C, 30 µg), Nitrofurantion (F, 300 µg), and Trimethoprim/Sulfamethoxazole (SXT, 1.25/23.75 µg).
The one-minute β-lactamase test was performed as described [19] to test for β-lactamase production by the bacterial isolates using the double disk synergy technique modified by Lautenbach, et al. [13]. Briefly, a single colony from an overnight blood agar culture was suspended in sterile 0.9% normal saline solution in a sterile tube. The turbidity of the test bacteria was adjusted by dilution to obtain 0.5 McFarland standards. A cotton swab was soaked in the suspension tube and the test bacteria were spread on Mueller-Hinton agar plates (Oxoid Limited, Hants, England). The disks containing the standard ceftazidime, ceftriaxone, cefotaxime, and aztreonam at 30 µg were placed 25 mm apart (center to center) from amoxicillin/clavulanic acid 20/10 µg. After an incubation period of 18 hours at 35°C, the zone of inhibition between Ceftazidime, Ceftriaxone, cefotaxime or aztreonam and amoxicillin/clavulanic acid indicated the presence of an ESBL-producing isolate. E. coli ATCC 25922 was used as negative control.
A total of 333 bacterial isolates were isolated from patients and healthy individuals. Of these, 208 strains were isolated from patients and 125 were isolated from the healthy volunteers. Out of the 208 bacterial strains isolated from patients, 149 were Escherichia coli (71.6%), 35 were Klebsiella pneumoniae (16.8%), 6 were Klebsiella oxytoca (2.9%), 6 were Proteus mirabilis (2.9%), 5 were Enterobacter cloacae (2.4%), 4 were Citrobacter freundii (1.9%), 2 were Enterobacter agglomerans (0.96%) and 1 was Salmonella typhi (0.48%). On the other hand, of the total 125 isolates from the healthy volunteers, 91 were E. coli (72.8%); 24 were K. pneumoniae (19.2%); 5 were Ent. cloacae (4%) and 5 were C. freundii (4%).
Organism Patients Healthy Controls Total
Isolates ESBL (%) Isolates ESBL (%) Isolates ESBL (%)
E. coli 149 8 (5.4) 91 1 (1.1) 240 9 (3.8)
K. pneumoniae 35 4 (11.4) 24 2 (8.3) 59 6 (10.2)
K. oxytoca 6 0 0 0 6 0
P. mirabilis 6 0 0 0 6 0
Ent. cloacae 5 0 5 0 10 0
C. freundii 4 0 5 0 9 0
S. typhi 1 0 0 0 1 0
Ent. agglomerans 2 0 0 0 2 0
Total 208 12 (5.8) 125 3 (2.4) 333 15 (4.5)
Table 1: Distribution of extended-spectrum β-lactamase producing and non-producing Enterobacteriaceae isolated from patients fecal and urine samples and fecal healthy control samples collected from Brack-Alshati, Fezzan, Libya.
Out of the total 333 Enterobacteriaceae isolates from both patients and healthy controls, only 15 (4.5%) isolates were positive for ESBL as tested by the double disc synergy test. Among those 15 isolates, 12 (3.6%) isolates were from patients and 3 (0.9%) isolates were from healthy volunteers. In patients, 8 (5.36%) out of 149 E. coli strains, and 4 (11.4%) out of 35 K. pneumoniae strains were ESBL-producers. However, only a single (1.09%) E. coli strain out of 91 and 2 (8.33%) K. pneumoniae strains out of 24 isolated from healthy group produced ESBL. Of the ESBL-producing strains, 11 of patients’ 12 isolates were from urine samples. Almost all the ESBL-producing isolates were consistently more resistant to a wide variety of antimicrobial agents than the non-ESBL-producers. The most distinguishing feature of ESBL-producing E. coli and K. pneumoniae was their higher level of resistance to ampicillin, amoxicillin, ticarcillin, cephalothin compared to the non-ESBL-producing isolates. ESBL-producing E. coli isolates were also resistant to third generation cephalosporins such as ceftazidime, ceftriaxone, and cefotaxime with a range of 11-33%, while non-ESBLs E. coli isolates were sensitive to these drugs.
Antibiotic K. pneumoniae E. coli
% Resistance % Resistance
Ampicillin 100 85 100 45
Amoxicillin 100 85 100 45
Ticarcillin 100 85 100 45
Cephalothin 83 15 100 42
Cefoxitin 67 15 22 16
Cefoperazone 17 0 22 3
Cefotaxime 50 0 33 0
Ceftazidime 50 0 11 0
Ceftriaxone 50 0 33 0
Imipenem 0 0 0 0
Aztreonam 17 0 0 0
Piperacillin/Tazobactam 0 4 22 0
Amoxicillin/clavulanic acid 67 4 33 6
Ciprofloxacin 17 4 44 10
Nalidixic acid 17 9 55 10
Nitrofurantion 50 25 11 3
Choramphenicol 50 11 33 10
Tetracycline 50 19 44 42
Trimethoprim/Sulphamethaxzole 33 23 33 36
Gentamicin 33 0 55 3
Table 2: Comparison of resistance patterns of extended-spectrum β-lactamase-producing and non-producing K. pneumonia and E. coli isolated from patients fecal and urine samples and fecal healthy control samples collected from Brack-Alshati, Fezzan, Libya to antibiotics.
The 15 ESBL-producing isolates showed variable resistance patterns. The resistance to cefotaxime, ceftriaxone, ceftazidime, and aztreonam were 40%, 40%, 26.7% and 6.7%, respectively. The correlation between the zone of inhibition recorded for the five antibiotics (ceftazidime, cefotaxime, ceftriaxone, aztreonam and augmentin) tested with the disk diffusion test and the zone of inhibition of the same antibiotics used above with the double disk synergy test (DDS, 25 mm) have revealed a positive correlation for both E. coli (r = 95.2%, p = 0.001) and K. pneumoniae (r = 88.3%, p = 0.001) as shown in Figure 1, suggesting equal validity for the two methods.
Figure 1: Correlation of the result of the two methods: Double Disk Synergy (DDS) and Disk Diffusion Test (DDT)-for detection of β-lactamase production in K. pneumoniae (Panel A) and E. coli (Panel B) isolated from patients fecal and urine samples and fecal healthy control samples collected from Brack-Alshati, Fezzan, Libya (p = 0.00).
The results of β-lactamase testing revealed that 119 of the E. coli isolates (80%), 52 of K. pneumonia (88%), 9 of Ent. cloacae (90%), 5 of K. oxytoca (83.3%), 3 of C. freundii (33.3%), and 1 of Ent. agglomerans (50%) did not produced β-lactamase. Among E. coli isolates, 9 strains (3.8%) were positive for ESBL production. Similarly, among the K. pneumoniae isolates, six strains (10.2%) were positive for both.
K. pneumoniae isolated from patients showed higher levels of resistance against almost all the antimicrobials tested compared to K. pneumoniae isolates from the healthy volunteers.
Figure 2: Comparison of antibiotics resistance of K. pneumoniae (panel A) and E. coli (panel B) isolated from patients fecal and urine samples (light shaded bars) and fecal healthy control samples (dark shaded bars) collected from Brack-Alshati, Fezzan, Libya.
All 39 (100%) K. pneumoniae isolates from patients were resistant to ampicillin, amoxicillin and ticarcillin. In contrast, only 67% of K. pneumoniae strains isolated from the healthy group were resistant to the same antibiotics (p < 0.05). A similar pattern was seen among E. coli isolates from patients that showed high level of resistance to the majority of the antimicrobials compared to E. coli isolates from the healthy group.
For instance, a range of 48-60% of isolates were resistant to the commonly used drugs including ampicillin, amoxicillin, ticarcillin, cephalothin and tetracycline compared with resistance rates for the healthy group (p < 0.05). Other antibiotics including cefoxitin, cefotaxime, ceftriaxone, augmentin, nalidixic acid and trimethoprim/sulphamethaxzole showed variable antimicrobial efficacy against isolates from both patients and healthy group with no statistical significance difference for each of E. coli and K. pneumoniae.
The prevalence of Enterobacteriaceae strains producing ESBLs varies worldwide. The highest rates among K. pneumoniae isolates from clinical specimens were reported from Latin America (44%), Asia/Pacific Rim (22.4%), Europe (13.3%), and North America (7.5%). A similar trend was shown for E. coli in terms of specific geographical variation but at lower prevalence rates of 13.5%; 12%; 7.6% and 2.2%, respectively [12]. In our study, a much lower rate of 4.5% of all isolates-from both patients and healthy volunteers were ESBL producers. Such rate was higher considering patients’ samples only (5.8% ESBL-producers). This is comparable to 6.3% reported by Bonfiglio in Italy [20]. A higher percentage of 13.4% among E. coli isolates from diarrhea stool samples of Northern Libyan children has also been recorded; while nine E. coli isolates (6.7%) demonstrated AmpC β-lactamases [17]. However, this prevalence is lower than those reported in other countries. For instance, it was reported that the prevalence was 55% in Jordan [21], 42% in Israel [22], 36% in Saudi Arabia [23], 38.5% in Egypt and 27.4% in Greece [24]. Countries of the Gulf Cooperation Council share a high prevalence of ESBL-and carbapenemase-producing Gram-negative bacilli, most of which are associated with nosocomial infections [25]. Infections with bacteria producing extended-spectrum beta-lactamases (ESBLs) are increasing across Africa too. ESBL-producing Enterobacteriaceae are significant causes of infections and antibiotic resistance at Korle-Bu Teaching Hospital in Accra, Ghana with ESBL expression rate of 49.3% in clinical samples [26].
Nonetheless, lower prevalence rates were also reported from other countries such as Denmark with less than 1% prevalence in the Copenhagen area [27]. Variability in the reported ESBL production prevalence could be attributed to a number of factors. For most of these types of studies, bacteria were isolated from ICUs patients and other hospitalized patients. Furthermore, studies looking for ESBL prevalence are usually performed on bacterial isolates from nosocomial infections. This in return may favour the finding of Enterobacteriaceae strains that produce ESBL and hence inflating the percentage of prevalence of ESBL-producing bacteria [12,28-30]. Antibiotic policies and protocols implemented at different geographical regions may also contribute to these differences in prevalence [6,9, 31,32]. A Saudi study reported 12.7% rate of ESBL expression among isolates from fecal specimens of healthy individuals and community outpatients. Of these, 87 (95.6%) were E. coli and 4 (4.4%) Klebsiella pneumoniae [30]. The community could be a reservoir of these ESBL-producing bacteria because rate of fecal carriage of ESBL-producers was very comparable among healthy persons (12.3%) and community outpatients (13.7%). The extensive usage of antibiotics, particularly non-prescription empirical usage, may correlate with greater prevalence due to positive selection. Moreover, environmental and genetic background susceptibility factors could have a significant impact on prevailing microbial ecology [33].
The prevalence of ESBL was greater among K. pneumoniae strains compared to E. coli in the present investigation. This is in agreement with previous studies [20-22,34-36]. Out of 125 isolates from the healthy volunteers, ESBL production was found only in 3 (2.4%) strains. Although a very low prevalence, healthy carriers of ESBL-producing bacteria may act as a reservoir for the spread of multi-drug resistant bacteria in the community. In general, strains of E. coli and K. pneumoniae that produced ESBLs were more resistant to the β-lactam and non-β-lactam antibiotics tested than non-ESBL expressing strains. Only imipenem was effective against both groups. This was in agreement with a number of other reported studies [24,37,38]. The susceptibility pattern for piperacillin/tazobactam against ESBL-producing bacteria has been extremely variable. In the present investigation, the sensitivity rates of both ESBL- and non-ESBL-producing strainsof K. pneumoniae ranged from 94-100%. This is in agreement with the findings at Asia-Pacific region and South Africa medical centers, and other studies [3,39-41]. However, ESBL-producing E. coli strains have shown a greater resistance to  
Although, it has been reported that gentamicin can be used against ESBL-producing bacteria [41], we have found that 55% of ESBL-producing E. coli were resistant to gentamicin, compared with 3% of the non-ESBL-producing E. coli. Similarly, 33% of ESBL-producing K. pneumoniae were resistant to gentamicin, whereas, none of the non-ESBLs-producing isolates were resistant to the same drug. These findings are in agreement with other data reported from UK [47]. Nonetheless, another report [40], suggested that ESBL-producing strains may not necessarily be more susceptible to gentamicin. A Ghanaian study showed marked increase in minimum inhibitory concentrations of ESBL-producing Enterobacteriaceae isolated from clinical samples compared with other strains. The study found that 17% of ESBL-producers were resistant to two or more antibiotics (aminoglycosides, fluoroquinolones, sulfonamide, and carbapenems), whereas, only 3.2% of non-ESBL-producers were multidrug resistant [26].
It is a well known fact that using the disk diffusion test as a single method for detection of ESBL expression is not adequate. Other investigators have reported similar observations [20,21,48-50]. ESBL-producers are able to hydrolyze extended-spectrum penicillins, cephalosporins and aztreonam. The minimal inhibitory concentration (MICs) of these antimicrobial agents may be within the sensitivity range. For this reason, CLSI guidelines recommends that ESBL-producers be reported as resistant to all penicillins and cephalosporins and aztreonam, even when they show sensitivity to these agents by such conventional tests [18]. A positive significant correlation between the two antimicrobial sensitivity methods was evident for E. coli and K. pneumoniae. Therefore, we and other investigators recommend the use of the double disk synergy in conjunction with the disk diffusion test for the detection of ESBL-producing bacteria in the laboratory setting [51].
According to the present results, strains isolated from patients were more resistant to all antibiotics tested in comparison to those isolated from healthy individuals. A similar observation was noted by Kunin and Liu who recorded high frequency of antibiotics use and resistance among patients presenting at emergency wards, clinics and the community in Taiwan [52], and in patients from the Gulf area [53]. However, there were few exceptions where K. pneumoniae isolates were more resistant to cefoxitin and nitrofurantion. C. freundii was more resistant to augmentin, while Ent. cloacae isolates were more resistant to ampicillin, amoxicillin, cefoxitin, cephalothin and nitrofurantion in the healthy group of individuals in the present study . The differences in the overall antibiotic resistance of E. coli and K. pneumoniae in patients and the healthy group were statistically significant (p < 0.05). Nearly 20% of ESBL-producing Enterobacteriaceae isolates were from community-associated intra-abdominal infections and isolates from hospital-associated intra-abdominal infections had more complicated pattern of β-lactamases combinations than isolates from the community from Asia-Pacific region [54].
Our results have shown that patients with gastrointestinal and urinary tract infections harboured more ESBL producing Enterobacteriaceae strains compared with healthy individuals in the community. Although the overall prevalence of ESBL producing bacteria presented in our study is relatively not higher in comparison with other figures reported worldwide. However, the bacterial strains isolated from the patients were more resistant to antibiotics generally used in compacting infections than strains isolated from the healthy volunteers. The high resistance rates to most of the antibiotics tested mandates increased surveillance and molecular characterization of these isolates. Additionally policies to reduce misuse of antibiotics are mandatory, and to stopping investing money in useless antibiotics.
  1. Gniadkowski M. “Evaluation and epidemiology of extended-spectrum beta-lactamases (ESBLs) and ESBL-producing microorganisms”. Clinical Microbiology and Infection 7.11 (2001): 597-608.
  2. Nassima Djahmi., et al. “Epidemiology of carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii in Mediterranean countries”. BioMed Research International 2014 (2014): 1-11.
  3. Knothe H., et al. “Transferable resistance to cefotaxime, cefoxitin, cefamandole and cefuroxime in clinical isolates of Klebsiella pneumoniae and Serratia marcescens. Infection 11.6 (1983): 315-317.
  4. Bradford PA. “Extended-spectrum β-lactamases in the 21st century: characterization, Epidemiology, and detection of this important resistance threat”. Clinical Microbiology Reviews 14.4 (2001): 933-951.
  5. Livermore DM. “Beta-lactamases in laboratory and clinical resistance”. Clinical Microbiology Reviews 8.4 (1995): 557-584.
  6. Bush Karen., et al. “A functional classification scheme for β- lactamases and its correlation with molecular structure”. Antimicrobial Agents and Chemotherapy 39.6 (1995): 1211-1233.
  7. Paterson DL. “Resistance in gram-negative bacteria: Enterobacteriaceae”. The American Journal of Medicine 119.6 (2006): S20-S28.
  8. Yong D., et al. “Characterization of a new metallo-beta-lactamase gene, blaNDM-1, and a novel erythromycin esterase gene carried on a unique genetic structure in Klebsiella pneumoniaesequence type 14 from India”. Antimicrobial Agents and Chemotherapy 53.12 (2009): 5046-5054.
  9. Poulou A., et al. “Outbreak caused by an ertapenem-resistant, CTX-M-15-producing Klebsiella pneumoniae sequence type 101 clone carrying an OmpK36 porin variant”. Journal of Clinical Microbiology 51.10 (2013): 3176-3182.
  10. Rupp ME and Fey PD. “Extended spectrum beta-lactamase (ESBL) - producing Enterobacteriaceae considerations for diagnosis, prevention and drug treatment”. J Drugs 63.4 (2003): 353-365.
  11. Colonder R. “Extended-spectrum beta-lactamases: A challenge for clinical microbiologists and infection control specialists”. American Journal of Infection Control 33.2 (2005): 104-107.
  12. Reinert RR., et al. “Antimicrobial susceptibility among organisms from the Asia/Pacific Rim, Europe and Latin and North America collected as part of TEST and the in vitro activity of tigecycline”. Journal of Antimicrobial Chemotherapy 60.5 (2007): 1018-1029.
  13. Lautenbach E., et al. “Extended-spectrum β-lactamases producing Escherichia coli and Klebsiella pneumoniae: risk factors for infection and impact on resistance of outcomes”. Clinical Infectious Diseases 32.8 (2001): 1162-1171.
  14. Coque TM., et al. “Increasing prevalence of ESBL-producing Enterobacteriaceae in Europe”. Euro Surveillance 13.47 (2008): 19044.
  15. Paterson DL. “Recommendation for treatment of severe infections caused by Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs)”. Clinical Microbiology and Infection 6.9 (2000): 460-463.
  16. Buzayan MM., et al. “Detection of extended spectrum β-lactamases among urinary Escherichia coli and Klebsiella pneumoniae from two centres”. Jamahiriya Medical Journal 10 (2010): 10-16.
  17. Ahmed SF., et al. “Fecal carriage of extended-spectrum β-lactamases and AmpC-producing Escherichia coli in a Libyan community”. Annals of Clinical Microbiology and Antimicrobials 13.22 (2014): 1-8.
  18. NCCLs (2002) Performance standards for antimicrobial disk susceptibility tests, Twelfth Informational Supplement, NCCLs document M100-S12, NCCLs, Wayne. PA.
  19. Escamilla J. “A modified one-minute β-lactamases test”. Antimicrobial Agents and Chemotherapy 9.1 (1976): 196-198.
  20. Bonfiglio G., et al. “Epidemiology of bacterial resistance in gastrointestinal pathogens in a tropical area”. International Journal of Antimicrobial Agents 20.5 (2002): 387-389.
  21. Shehabi AA., et al. “High incidence of Klebsiella pneumoniae clinical isolates to extended-spectrum β- lactam drugs in intensive care units”. Diagnostic Microbiology and Infectious Disease 36.1 (2000): 53-56.
  22. Venezia SN., et al. “Occurrence and phenotypic characteristic of Extended-spectrum beta-lactamases among member of the family of Enterobacteriaceae at the Tel-Aviv Medical Center and evaluation of diagnostic tests”. Journal of Clinical Microbiology 41.1 (2003): 155-158.
  23. Babay HA. “Detection of extended-spectrum β-lactamases in members of the family enterobacteriaceae of a teaching hospital, Riyadh. Kingdom of Saudi Arabia, Saudi Medical Journal 23.2 (2002): 186-190.
  24. Bouchillon SK., et al. “Determining incidence of extended-spectrum β-lactamase producing Enterobacteriaceae, vancomycin- resistant Enterococcus faeciumand Methicillin- resistant Staphylococcus aureus in 38 Centers from 17 countries: the PEARLS study 2001-2002. International Journal of Antimicrobial Agents 24 (2004):119-124.
  25. Zowawi HM., et al. “β-Lactamase Production in Key Gram-Negative Pathogen Isolates from the Arabian Peninsula”. Clinical Microbiology Reviews 26.3 (2013): 361-380.
  26. Obeng Nkrumah N., et al. “High levels of extended-spectrum beta-lactamases in a major teaching hospital in Ghana: the need for regular monitoring and evaluation of antibiotic resistance”. The American Journal of Tropical Medicine and Hygiene 89.5 (2013): 960-964.
  27. Kjerulf A., et al. “The prevalence of ESBL-producing E. coli and Klebsiella strains in the Copenhagen area of Denmark”. APMIS 116.2 (2008): 118-124.
  28. Gardam M and Conly J. “Extended spectrum beta-lactam enterobacteriaceae: The nosocomial pathogen du jour? Where does the list end”? The Canadian Journal of Infectious Diseases 6 (2000): 1425.
  29. Garcia JA., et al. “Antimicrobial resistance in gram-negative isolates from European-intensive care units: data from the meropenem yearly susceptibility test information collection (MYSTIC) program”. Journal of Chemotherapy 14.1 (2002): 25-32.
  30. Kader AA and Kumar AK. “Prevalence of extended-spectrum β-lactamase among multidrug resistant gram-negative isolates from a general hospital in SaudiArabia”. Saudi Medical Journal 25.5 (2004): 570-574.
  31. Jones RN., et al. “Antimicrobial activity against trains of Escherichia coli and Klebsiella spp. with resistance phenotypes consistent with an extended-Spectrum β-lactamases in Europe”. Clinical Microbiology and Infection 9.7 (2003): 708-712.
  32. Chanawong A., et al. “Dissemination and evolution of new Plasmid-mediated extended-β-lactamases among Enterobacteriaceae isolates from the People’s Republic of China”. Clinical Microbiology and Infection 6(2000): 77.
  33. Kader AA and Kamath KA. “Faecal carriage of extended-spectrum beta-lactamase-producing bacteria in the community”. Eastern Mediterranean Health Journal 15.6 (2009): 1365-1370.
  34. Hadziyannis E., et al. “Screening and confirmatory testing for extended-spectrum beta- lactamase (ESBL) inEscherichia coli, Klebsiella pneumoniae andKlebsiella oxytoca clinical isolates. Diagnostic Microbiologyand Infectious Disease 36.2 (2000): 113-117.
  35. Saurina G., et al. “Antimicrobial resistance in Enterobacteriaceae in Brooklyn, N.Y: epidemiology and relation to antibiotic usage patterns”. Journal of Antimicrobial Chemotherapy 45.6 (2000): 895-898.
  36. Bell JM., et al. “Prevalence of extended-spectrum beta-lactamase (ESBL) producing clinical isolates in the Asia-Pacific region and South Africa: Regional results from SENTRY antimicrobial surveillance program (1998-99)”. Diagnostic Microbiology and Infectious Disease 42.3 (2002): 193-198.
  37. Lee SH and Jeong SH. “Antibiotic susceptibility of bacterial strains isolated from patients with various infections”. Letters in Applied Microbiology 34.3 (2002): 215-221.
  38. Xiong Z., et al. “Investigation of extended-spectrum beta-lactamase in Klebsiella pneumoniae and Escherichia coli from China”. Diagnostic Microbiology and Infectious Disease 44.2 (2002): 195-200.
  39. El Kholy A., et al. “Antimicrobial resistance in Cairo, Egypt 1999-2000: a survey of five Hospitals. Journal of Antimicrobial Chemotherapy 51.3 (2003): 625-630.
  40. Villanueva FD., et al. “Extended-spectrum beta-lactamases-production among Escherichia coli and Klebsiella spp. at the makati Medical Center: Tentative solutions”. Journal Microbiology Infectious Diseases 32 (2003): 103-108.
  41. Schiappa DA., et al. “Ceftazidime-resistant Klebsiella pneumoniae and Escherichia coli blood stream infection: a case-control and molecular epidemiologic investigation”. The Journal ofInfectious Diseases 174.3 (1996): 529-536.
  42. Tawfik AF., et al. “Prevalence and genetic characteristics of TEM, SHV, and CTX-M in clinical Klebsiella pneumoniae isolates from Saudi Arabia”. Microbial Drug Resistance 17.3 (2011): 383-388.
  43. Al-Agamy MH., et al. “Prevalence and molecular characterization of extended-spectrum β-lactamase-producing Klebsiella pneumoniae in Riyadh, Saudi Arabia”. Annals of Saudi Medicine 29.4 (2009): 253-257.
  44. Al-Agamy MH., et al. “Molecular characteristics of extended-spectrum β-lactamase-producing Escherichia coli in Riyadh: emergence of CTX-M-15-producing E. coli ST131”. Annals of Clinical Microbiology and Antimicrobials 13.4 (2014): doi: 10.1186/1476-0711-13-4.
  45. Nakhaei Moghaddam M., et al. “Prevalence and Molecular Characterization of Plasmid-mediated Extended-Spectrum β-Lactamase Genes (balaTEM, blaCTX and blASHV) Among Urinary Escherichia coli Clinical Isolates in Mashhad, Iran”. Iranian Journal of Basic Medical Sciences 15.3 (2012): 833-839.
  46. Voets GM., et al. “Population distribution of Beta-lactamase conferring resistance to third-generation cephalosporins in human clinical Enterobacteriaceae in the Netherlands”. PLoS One 7.12 (2012): e52102.
  47. Elvy JA., et al. “Extended Spectrum β-Lactamase (ESBL) producing bacteria in a large UK NHS Hospital Trust”. Journal of Infection 55 (2007): e59.
  48. Shen D., et al. “Characterization of extended spectrum β-lactamases-producing Klebsiellapneumoniae from Beijing, China”. International Journal of Antimicrobial Agents18.2 (2001): 185-188.
  49. Ho PL., et al. “Comparison of screening methods for detection of extended-spectrum β-lactamases and their Prevalence among Escherichia coliand Klebsiella spp. in Hong Kong”. APMIS 108.3 (2000): 237-240.
  50. Jacoby GA and Han P. “Detection of extended-spectrum β-lactamases in clinical isolates of Klebsiella and Escherichia coli”. Journal of Clinical Microbiology 34.4 (1996): 908-911.
  51. Gualy Z., et al. “Ability of different methods to detect extended-spectrum β-lactamases in enterobacteriaceae”. Clinical Microbiology and Infection 7 (2001): 394.
  52. Kunin CM Liu YC. “Excessive use of antibiotics in the community associated with delayed admission and masked diagnosis of infectious diseases”. Journal of Microbiology, Immunology and Infection 35.3 (2002): 141-146.
  53. Khanfar HS., et al. “Extended spectrum beta-lactamases (ESBL) in Escherichia coli and Klebsiella pneumoniae: trends in the hospital and community settings”.Journal of Infection in Developing Countries 3.4 (2009): 295-299.
  54. Sheng WH., et al. “Distribution of extended-spectrum β-lactamases, AmpC β-lactamases, and carbapenemases among Enterobacteriaceae isolates causing intra-abdominal infections in the Asia-Pacific region: results of the study for Monitoring Antimicrobial Resistance Trends (SMART)”. Antimicrobial Agents and Chemotherapy57.7 (2013): 2981-2988.
Copyright: © 2015 Ibrahim A Taher., et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

PubMed Indexed Article

EC Pharmacology and Toxicology
LC-UV-MS and MS/MS Characterize Glutathione Reactivity with Different Isomers (2,2' and 2,4' vs. 4,4') of Methylene Diphenyl-Diisocyanate.

PMID: 31143884 [PubMed]

PMCID: PMC6536005

EC Pharmacology and Toxicology
Alzheimer's Pathogenesis, Metal-Mediated Redox Stress, and Potential Nanotheranostics.

PMID: 31565701 [PubMed]

PMCID: PMC6764777

EC Neurology
Differences in Rate of Cognitive Decline and Caregiver Burden between Alzheimer's Disease and Vascular Dementia: a Retrospective Study.

PMID: 27747317 [PubMed]

PMCID: PMC5065347

EC Pharmacology and Toxicology
Will Blockchain Technology Transform Healthcare and Biomedical Sciences?

PMID: 31460519 [PubMed]

PMCID: PMC6711478

EC Pharmacology and Toxicology
Is it a Prime Time for AI-powered Virtual Drug Screening?

PMID: 30215059 [PubMed]

PMCID: PMC6133253

EC Psychology and Psychiatry
Analysis of Evidence for the Combination of Pro-dopamine Regulator (KB220PAM) and Naltrexone to Prevent Opioid Use Disorder Relapse.

PMID: 30417173 [PubMed]

PMCID: PMC6226033

EC Anaesthesia
Arrest Under Anesthesia - What was the Culprit? A Case Report.

PMID: 30264037 [PubMed]

PMCID: PMC6155992

EC Orthopaedics
Distraction Implantation. A New Technique in Total Joint Arthroplasty and Direct Skeletal Attachment.

PMID: 30198026 [PubMed]

PMCID: PMC6124505

EC Pulmonology and Respiratory Medicine
Prevalence and factors associated with self-reported chronic obstructive pulmonary disease among adults aged 40-79: the National Health and Nutrition Examination Survey (NHANES) 2007-2012.

PMID: 30294723 [PubMed]

PMCID: PMC6169793

EC Dental Science
Important Dental Fiber-Reinforced Composite Molding Compound Breakthroughs

PMID: 29285526 [PubMed]

PMCID: PMC5743211

EC Microbiology
Prevalence of Intestinal Parasites Among HIV Infected and HIV Uninfected Patients Treated at the 1o De Maio Health Centre in Maputo, Mozambique

PMID: 29911204 [PubMed]

PMCID: PMC5999047

EC Microbiology
Macrophages and the Viral Dissemination Super Highway

PMID: 26949751 [PubMed]

PMCID: PMC4774560

EC Microbiology
The Microbiome, Antibiotics, and Health of the Pediatric Population.

PMID: 27390782 [PubMed]

PMCID: PMC4933318

EC Microbiology
Reactive Oxygen Species in HIV Infection

PMID: 28580453 [PubMed]

PMCID: PMC5450819

EC Microbiology
A Review of the CD4 T Cell Contribution to Lung Infection, Inflammation and Repair with a Focus on Wheeze and Asthma in the Pediatric Population

PMID: 26280024 [PubMed]

PMCID: PMC4533840

EC Neurology
Identifying Key Symptoms Differentiating Myalgic Encephalomyelitis and Chronic Fatigue Syndrome from Multiple Sclerosis

PMID: 28066845 [PubMed]

PMCID: PMC5214344

EC Pharmacology and Toxicology
Paradigm Shift is the Normal State of Pharmacology

PMID: 28936490 [PubMed]

PMCID: PMC5604476

EC Neurology
Examining those Meeting IOM Criteria Versus IOM Plus Fibromyalgia

PMID: 28713879 [PubMed]

PMCID: PMC5510658

EC Neurology
Unilateral Frontosphenoid Craniosynostosis: Case Report and a Review of the Literature

PMID: 28133641 [PubMed]

PMCID: PMC5267489

EC Ophthalmology
OCT-Angiography for Non-Invasive Monitoring of Neuronal and Vascular Structure in Mouse Retina: Implication for Characterization of Retinal Neurovascular Coupling

PMID: 29333536 [PubMed]

PMCID: PMC5766278

EC Neurology
Longer Duration of Downslope Treadmill Walking Induces Depression of H-Reflexes Measured during Standing and Walking.

PMID: 31032493 [PubMed]

PMCID: PMC6483108

EC Microbiology
Onchocerciasis in Mozambique: An Unknown Condition for Health Professionals.

PMID: 30957099 [PubMed]

PMCID: PMC6448571

EC Nutrition
Food Insecurity among Households with and without Podoconiosis in East and West Gojjam, Ethiopia.

PMID: 30101228 [PubMed]

PMCID: PMC6086333

EC Ophthalmology
REVIEW. +2 to +3 D. Reading Glasses to Prevent Myopia.

PMID: 31080964 [PubMed]

PMCID: PMC6508883

EC Gynaecology
Biomechanical Mapping of the Female Pelvic Floor: Uterine Prolapse Versus Normal Conditions.

PMID: 31093608 [PubMed]

PMCID: PMC6513001

EC Dental Science
Fiber-Reinforced Composites: A Breakthrough in Practical Clinical Applications with Advanced Wear Resistance for Dental Materials.

PMID: 31552397 [PubMed]

PMCID: PMC6758937

EC Microbiology
Neurocysticercosis in Child Bearing Women: An Overlooked Condition in Mozambique and a Potentially Missed Diagnosis in Women Presenting with Eclampsia.

PMID: 31681909 [PubMed]

PMCID: PMC6824723

EC Microbiology
Molecular Detection of Leptospira spp. in Rodents Trapped in the Mozambique Island City, Nampula Province, Mozambique.

PMID: 31681910 [PubMed]

PMCID: PMC6824726

EC Neurology
Endoplasmic Reticulum-Mitochondrial Cross-Talk in Neurodegenerative and Eye Diseases.

PMID: 31528859 [PubMed]

PMCID: PMC6746603

EC Psychology and Psychiatry
Can Chronic Consumption of Caffeine by Increasing D2/D3 Receptors Offer Benefit to Carriers of the DRD2 A1 Allele in Cocaine Abuse?

PMID: 31276119 [PubMed]

PMCID: PMC6604646

EC Anaesthesia
Real Time Locating Systems and sustainability of Perioperative Efficiency of Anesthesiologists.

PMID: 31406965 [PubMed]

PMCID: PMC6690616

EC Pharmacology and Toxicology
A Pilot STEM Curriculum Designed to Teach High School Students Concepts in Biochemical Engineering and Pharmacology.

PMID: 31517314 [PubMed]

PMCID: PMC6741290

EC Pharmacology and Toxicology
Toxic Mechanisms Underlying Motor Activity Changes Induced by a Mixture of Lead, Arsenic and Manganese.

PMID: 31633124 [PubMed]

PMCID: PMC6800226

EC Neurology
Research Volunteers' Attitudes Toward Chronic Fatigue Syndrome and Myalgic Encephalomyelitis.

PMID: 29662969 [PubMed]

PMCID: PMC5898812

EC Pharmacology and Toxicology
Hyperbaric Oxygen Therapy for Alzheimer's Disease.

PMID: 30215058 [PubMed]

PMCID: PMC6133268

News and Events

February Issue Release

We always feel pleasure to share our updates with you all. Here, notifying you that we have successfully released the February issue of respective journals and can be viewed in the current issue pages.

Submission Deadline for April Issue

Ecronicon delightfully welcomes all the authors around the globe for effective collaboration with an article submission for the March issue of respective journals. Submissions are accepted on/before March 12, 2020.

Certificate of Publication

Ecronicon honors with a "Publication Certificate" to the corresponding author by including the names of co-authors as a token of appreciation for publishing the work with our respective journals.

Best Article of the Issue

Editors of respective journals will always be very much interested in electing one Best Article after each issue release. The authors of the selected article will be honored with a "Best Article of the Issue" certificate.

Certifying for Review

Ecronicon certifies the Editors for their first review done towards the assigned article of the respective journals.

Latest Articles

The latest articles will be updated immediately on the articles in press page of the respective journals.

Immediate Assistance

The prime motto of this team is to clarify all the queries without any delay or hesitation to avoid the inconvenience. For immediate assistance on your queries please don't hesitate to drop an email to