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PubMedDate not supplied

Effect of beta-lactamase expression on susceptibility of local isolates of Enterobacter cloacae, Serratia marcescens and Pseudomonas aeruginosa to beta-lactam antibiotics.

During surveillance studies, a total of 66 strains of gram-negative bacilli (28 Enterobacter cloacae, 20 Serratia marcescens and 18 Pseudomonas aeruginosa) with a reduced susceptibility to third-generation cephalosporins, aztreonam and amikacin were isolated from documented infections. All isolates were highly susceptible to imipenem and sparfloxacin. beta-Lactamase activity was demonstrated in all isolates of E. cloacae and S. marcescens, and in 77% of P. aeruginosa isolates. Inducible beta-lactamase activity was detected in 80, 65 and 40% of E. cloacae, S. marcescens and P. aeruginosa isolates, respectively, when cefoxitin was used as an inducer. More inducible beta-lactamase producers were observed when imipenem was used as an inducer. Isolates of E. cloacae, and to a lesser extent S. marcescens, expressed a wide spectrum of beta-lactamase activities. There was a good correlation between baseline beta-lactamase activity and the respective MIC of ceftazidime, cefotaxime and ceftriaxone, and to a lesser extent aztreonam in E. cloacae and S. marcescens isolates. Only one isolate of E. cloacae demonstrated an extended beta-lactamase activity. The data suggest that the resistance of E. cloacae and S. marcescens isolates to beta-lactam antibiotics is largely dependent upon hyperproduction of beta-lactamase.

Anti-Bacterial Agents↗
PubMedDate not supplied

Effect of ten new beta-lactam antibiotics on urine glucose test methods.

The effect of ten new beta-lactam antibiotics (cefoperazone, cefotaxime and its metabolite desacetylcefotaxime, ceftazidime, ceftizoxime, ceftriaxone, aztreonam, azlocillin, mezlocillin, piperacillin, and ticarcillin) on the accuracy of Clinitest, Diastix, and Tes Tape determinations of glycosuria was investigated. Solutions of each of the antibiotics were prepared in urine over a range of clinically obtainable drug concentrations. Urine samples from a healthy subject were used to prepare simulated diabetic urine by adding dextrose to achieve concentrations of 0.5%, 1%, and 2%. With penicillin derivatives, falsely elevated Clinitest readings generally were observed at lower glucose concentrations. When no glucose was present, cephalosporins and the monobactam, aztreonam, gave a dark green-black color that could only be interpreted as 0% on the Clinitest color chart. At higher urine glucose concentrations (1% and 2%), no interaction with Clinitest could be demonstrated, with the exception of a few falsely reduced readings. All urine solutions containing beta-lactam antibiotics were estimated accurately by both Diastix and Tes Tape. The unpredictability of the Clinitest-beta-lactam antibiotics interaction should discourage the use of this urine glucose test in patients who receive these drugs. The glucose-oxidase tests, Diastix and Tes Tape, may be used as qualitative tests for glycosuria in patients treated with beta-lactam antibiotics.

Adult↗
PubMedDate not supplied

Distribution and prevalence of antimicrobial resistance among gram-negative isolates in intensive care units (ICU) in Belgian hospitals between 1996 and 1999.

OBJECTIVE: To assess the distribution and prevalence of resistance rates among Gram-negative isolates in Belgian intensive care units (ICUs) between 1996 and 1999. METHODS: During 1996-1997 and 1998-1999, over a total period of 10 and 9 months respectively, members of the NPRS Belgian Study group collected, on clinical indications, 3029 consecutive initial isolates of Gram-negative bacteria from patients admitted to 26 Belgian hospitals and performed minimal inhibitory concentration (MIC) determinations by means of the E-test. Break-points were defined according to the criteria of the NCCLS. RESULTS: The overall distribution of bacterial species was, in decreasing order of frequency: Pseudomonas aeruginosa > E. coli > E. aerogenes > K. pneumoniae > P. mirabilis > S. marcescens > E. cloacae > K. oxytoca > M. morganii > Stenotrophomonas maltophilia > Acinetobacter spp. All together these species and genera constituted about 90% of all isolates. The frequency of resistance for all the initial Gram-negative isolates in 1998-9 were: amoxicillin-clavulanic acid 60%, piperacillin 31%, piperacillin-tazobactam 20%, cefuroxime 58%, ceftriaxone 31%, ceftazidime 17%, aztreonam 23%, cefepime 10%, imipenem 13%, gentamicin 12%, amikacin 12% and ciprofloxacin 21%. Apart for an increase in multiple drug resistance among P. aeruginosa isolates, no significant trends were observed neither in species distribution nor in the overall prevalence of antimicrobial resistance among Gram-negative isolates from Belgian ICUs between 1996-7 and 1998-9. CONCLUSIONS: Among Gram-negative isolates in Belgian ICUs, a very high frequency of resistance was seen to amoxicillin-clavulanic acid and cefuroxime, and rather high frequencies of resistance to piperacillin, ceftriaxone and aztreonam. Taking into account the species distribution and the prevalence of resistance, cefepime, imipenem, amikacin and gentamicin appeared generally suitable for empirical therapeutic use in severe ICU-acquired Gram-negative infections in Belgium. However, the therapeutic strategy should be adapted according to the local ecology of resistance.

Anti-Bacterial Agents↗
PubMed1996

In vitro activity of ampicillin-sulbactam against clinical multiresistant Acinetobacter baumannii isolates.

We evaluated the in vitro activity of ampicillin-sulbactam in comparison with that of broad-spectrum antimicrobial agents against Acinetobacter baumannii isolates. Two hundred and twelve clinical isolates collected between January 1993 and March 1995 from two tertiary hospitals located in São Paulo, Brazil were tested for susceptibility by the disk diffusion method against several broad-spectrum antimicrobial agents, including imipenem, ciprofloxacin, ceftazidime, aztreonam, amikacin, and polymyxin B. All strains were susceptible to polymyxin B. The second most active compound was the combination ampicillin-sulbactam (88% susceptibility). Only 79% of the isolates were susceptible to imipenem. Ciprofloxacin was active against 60 (28%) and amikacin against 34 (16%) isolates. Ceftazidime was the most active cephalosporin; however, only 9% of the isolates were susceptible to this compound. Both aztreonam and ampicillin alone showed very poor activity against this species (1% susceptibility). The prevalence of severe infections due to A. baumannii is increasing very rapidly in the tertiary hospitals of São Paulo and there are very few options for the treatment of these infections. Polymyxin B is invariably in vitro active against this species; however, this compound can cause severe side effects and is not commercially available for intravenous use in Brazil and in several other countries. Our results indicated that the combination ampicillin-sulbactam may be an alternative drug for the treatment of infections due to multiresistant A. baumannii; however, further studies are necessary to evaluate the clinical role of this compound for the treatment of severe infections.

Acinetobacter↗
PubMed1996

Transferable resistance to specific antibiotics in nosocomial strains of Pseudomonas aeruginosa from two teaching hospitals.

We describe the transfer of resistance to kanamycin, carbenicillin and cephaloridine to a recipient strain of Escherichia coli K-12 No. 3110 from three strains of Pseudomonas aeruginosa out of 146 strains tested in 1995. The P.aeruginosa No. 201, 203, 208 donor strains were isolated from patients in the University Clinics in Frankfurt, Germany. They were resistant to most beta-lactam antibiotics including cephalosporins of the 1st, 2nd and 3rd generation, imipenem, meropenem and aztreonam. They transferred kanamycin, carbenicillin and cephaloridine resistance determinants to recipient strain E.coli K-12 3110. These determinants were accompanied in strain P. aeruginosa No. 203, with a transfer of ceftazidime resistance determinants and in P.aeruginosa No. 208 with transfer of cefotaxime, ceftazidime and aztreonam resistance determinants. Transfer of antibiotic resistance was also studied in 13 nosocomial strains of P.aeruginosa collected for their ceftazidime and/or imipenem resistance in a large Teaching Hospital in Ostrava, Czech Republic. Six of these strains transferred carbenicillin and/or cephaloridine resistance to the E.coli K-12 3110 recipient strain. Resistance to kanamycin and cefotaxime was also co-transferred with carbenicillin and cephaloridine determinants. Ceftazidime, imipenem or ofloxacin resistance was not transferred and is thus, most probably, of chromosomal origin.

Carbenicillin↗
PubMed2001

Transferable antibiotic resistance in multiresistant nosocomial Acinetobacter baumannii strains from seven clinics in the Slovak and Czech Republics.

Sixty-seven multiresistant nosocomial Acinetobacter baumannii isolates from patients hospitalized mostly in intensive care units of seven clinics in Slovak and Czech Republic were tested to determine their ability to transfer antibiotic resistance. All isolates were resistant to kanamycin, ticarcillin, cephalothin, cefotaxime, ceftazidime, aztreonam and susceptible to carbapenems, sulbactam and ampicillin/sulbactam. Sixty-five out of 67 strains transferred resistance determinants to Escherichia coli K-12 and Proteus mirabilis P-38 recipients. Analysis of selected transconjugants by an indirect selection method showed a more variable pattern of transferred resistance determinants. The clonal spread of strains transferring resistance seems to be an additional risk for occurrence of strains resistant to ceftazidime and aztreonam.

Acinetobacter↗
PubMed1985

Temocillin sensitivity of Enterobacteriaceae species resistant to cefotaxime.

The in vitro activity of temocillin, cefotaxime, aztreonam and ceftazidime was tested against selected cefotaxime-resistant isolates (43 Enterobacter species, 37 Serratia marcescens, 16 Morganella morganii, 8 Klebsiella species) and cefotaxime-susceptible strains of the same species. Cross-resistance with a high degree of correlation was observed between cefotaxime and aztreonam or ceftazidime, but not between cefotaxime and temocillin.

Cefotaxime↗
PubMed2005

Tigecycline.

Tigecycline is the first member of a new class of broad-spectrum antibacterials, the glycylcyclines, that has been specifically developed to overcome the two major mechanisms of tetracycline resistance (ribosomal protection and efflux). In vitro, tigecycline was active against a wide range of Gram-positive and -negative aerobic and anaerobic bacteria implicated in complicated skin and skin structure infections (cSSSIs) and complicated intra-abdominal infections (cIAIs). Intravenously administered tigecycline (recommended dosage regimen 100 mg initially, followed by 50 mg every 12 hours for 5-14 days) has been approved by the US FDA for the treatment of cSSSIs and cIAIs. In well designed, pivotal phase III studies, tigecycline monotherapy was noninferior to combination therapy with vancomycin 1 g plus aztreonam 2 g every 12 hours in hospitalised adult patients with cSSSIs (two trials; pooled clinical cure rates, 86.5% vs 88.6%) or broad-spectrum therapy with imipenem/cilastatin 200-500 mg/200-500 mg every 6 hours in hospitalised adult patients with cIAIs (two trials; pooled clinical cure rates, 86.1% vs 86.2%). Tigecycline was generally well tolerated in phase III studies; nausea, vomiting and diarrhoea were the most frequent adverse events in patients treated with tigecycline or an active comparator (vancomycin plus aztreonam or imipenem/cilastatin).

Anti-Bacterial Agents↗
PubMed1991

Effects of different types and combinations of antimicrobial agents on endotoxin release from gram-negative bacteria: an in-vitro and in-vivo study.

Total and free endotoxin release in time from cultures of Escherichia coli by different antibiotics was studied in vitro for 4 h in relation to the antibiotic effect on viable counts and morphological features of the test cultures. The most rapid fall in viable counts was seen after treatment with imipenem or the combination of imipenem with tobramycin, accompanied by an early, but minimal increase (1.8-fold) of the total (free plus cell-bound) endotoxin level at 1 h. Total endotoxin levels increased approximately 5-fold upon incubation with ceftazidime, tobramycin or the combination of tobramycin with cefuroxime, whereas incubation with cefuroxime or aztreonam alone caused a late 22-and 49-fold increase in total endotoxin, respectively, at 4 h. In chloramphenicol treated cultures there was still an increase in viable counts during therapy, resulting in an ultimately 78-fold increase of mean levels of total endotoxin. Free endotoxin levels increased approximately 6-fold within 1 h upon treatment with imipenem, alone or in combination with tobramycin, or ceftazidime as the result of rapid lysis of bacteria. Treatment with cefuroxime or aztreonam induced a relatively late but much higher release of free endotoxin (118-and 222-fold, respectively), which was due to the formation of long filamentous structures during the first 2 h of incubation and eventually cell lysis. Both tobramycin and the combination of tobramycin with cefuroxime caused a more gradual rise in free endotoxin, with a +/- 15-fold increase in free endotoxin at 4 h. In chloramphenicol treated cultures, as in the control cultures, the level of free endotoxin remained proportional to the amount of viable organisms. We also studied plasma endotoxin levels in 20 patients with septic shock. 10 out of these 20 patients had a detectable endotoxemia (greater than 5 ng/l) on admission. We describe the patterns of plasma endotoxin in these patients during the first 24 h of antibiotic treatment. We conclude that, in the in-vitro study, values of total endotoxin, free endotoxin, and the rate of release of endotoxin varies with the antibiotic used. We also demonstrate that in patients under treatment for septic shock endotoxin release can be related to the administration of antibiotics.

Aged↗
PubMed1988

Properties of a broad spectrum beta-lactamase isolated from Flavobacterium meningosepticum GN14059.

A broad substrate-spectrum beta-lactamase was purified from Flavobacterium meningosepticum GN14059. The purified enzyme gave a single protein band on SDS-polyacrylamide gel electrophoresis. The molecular weight was estimated to be about 30,000 and the isoelectric point was 5.1. The enzyme hydrolyzed various beta-lactam antibiotics including oxyiminocephalosporins and aztreonam. Relative rates, with cephaloridine as 100, were cephalothin 200, cefazolin 48, cefuroxime 153, cefotaxime 51, ceftazidime 20, ampicillin 26, carbenicillin 19, and aztreonam 20. The enzyme activity was inhibited by clavulanic acid, sulbactam, imipenem and cephamycins.

Anti-Bacterial Agents↗
PubMed1999

[Susceptibility to selected antibiotics of Yersinia enterocolitica 03 strains, carrying and not carrying plasmid pYV].

A total of 199 clinical strains of Yersinia enterocolitica serotype O3, biotype 4 were tested for their susceptibility to antibiotics (158 strains carried the virulence plasmid pYV and 41 strains did not). 114 isolates were tested by standard disk diffusion method for 21 antibiotics. Almost all tested strains were resistant to ampicillin and cefazolin and susceptible to amoxycillin/clavulanate, cefaclor, cefamandole, cefuroxime, cefotaxime, ceftriaxone, aztreonam, imipenem, gentamicin, amikacin, netilmicin, tetracycline, doxycycline, chloramphenicol, ciprofloxacin, sulphamethoxazole, co-trimoxazole, trimethoprim and furazolidone. In addition minimal inhibitory concentrations (MICs) of 15 antibiotics were determined by agar dilution method for all 199 strains (158 plasmid positive and 41 strains plasmid negative). Third-generation cephalosporins such as cefotaxime and ceftriaxone and a fluoroquinolone (ciprofloxacin) were the most active antimicrobial agents, tested followed by aztreonam, imipenem, trimethoprim, tetracycline, gentamicin, chloramphenicol, amoxycillin/clavulanate, cefaclor, cefuroxime, amikacin, furazolidone and sulphamethoxazole. The present study demonstrated a high susceptibility of clinical strains of Y. enterocolitica to most of the tested antibiotics. In general, there was no significant difference between susceptibility of virulence plasmid pYV positive and virulence plasmid negative strains to antibacterial agents.

Drug Resistance, Microbial↗
PubMedDate not supplied

[Beta-lactam antibiotic sensitivity in Aeromonas spp. of clinical, animal, and environmental origin].

Susceptibility to beta-lactam antibiotics was investigated in Aeromonas spp. Microorganisms were isolated from both, clinical and water creek samples, as well as from processed raw chicken carcasses. Aeromonas like colonies were identified by means of Aerokey II and API 20 E System (Bio-Merieux). A. hydrophila prevailed both of human origin (44%) and water creek samples (41%), while A. caviae ranked first among raw chicken samples (65%). Dilution testing by Agar Method was performed to determine minimum inhibitory concentration (MIC), following NCCLS standards. All tested microorganisms were susceptible to third generation cephalosporin, cefepime, imipenem, aztreonam, and resistant to ampicillin. Only with cefepime and aztreonam exceptions, strains of human origin showed higher values of MIC90 than environmental ones. These results suggest that antibiotic resistance is mainly due to a steady environmental pressure, on account of the widely used above mentioned compounds.

Aeromonas↗
PubMedDate not supplied

Sensitivity of Enterobacteriaceae strains to the third generation cephalosporins.

The aim of this study was to evaluate the in vitro activity of cefotaxime, ceftriaxone, ceftazidime, ceftibuten and aztreonam against the clinical isolates of Enterobacteriaceae. MICROORGANISMS: A total of 973 enterobacteria isolated from clinical material (urine and faeces) were tested. Strains were collected during 1996-1998 period, in some centers of Eastern Romania. SENSITIVITY STUDY: MICs were performed using the agar dilution method following standardized techniques (NCCLS, 1994). Stock solutions of antibacterial agents were prepared from their respective powder forms, in concentrations ranging from 0.03 to 128 mg/ml. Our results show a good activity of the tested antimicrobials on Escherichia coli, Shigella spp and Klebsiella spp tested, and reveal a particular behaviour for Salmonella spp, characterized by a heterogenous susceptibility. In conclusion, cefotaxime, ceftriaxone, ceftazidime, ceftibuten and aztreonam were active at low concentrations against tested isolates. Against Salmonella spp, these agents were less active: percent of resistant strains by beta-lactamase production was significant.

Cephalosporins↗
PubMed2003

Pattern of bacteria and their antimicrobial susceptibility isolated from inanimate objects and hospital personnel.

Different inanimate samples collected from surgery wards and general operation theatre (GOT) as well as animate samples from surgery personnel were subjected to aerobic culture with the aim of identifying source of infections in surgical cases. The pattern of aerobic bacteria with antibiotic susceptibility isolated from those samples were reported in the present study. Out of 91 such samples, 53 and 26 were from different locations in general wards and OT respectively and 12 were comprising of hand swabs, throat swabs and nasal swabs from surgery personnel. Pathogenic bacteria were isolated from 34 samples having Pseudomonas spp. (18/34) in the top of the list followed by Esch. coli (14). Among the Esch.coli isolates resistance to cotrimoxazole, amoxicillin and doxycycline were 78.7%, 71.4% and 57.1% respectively, whereas sensitivity to aztreonam, ceftazidime, gentamicin and ciprofloxacin were 100%, 85.8%, 78.7% and 71.4% respectively. Ceftriaxone yielded intermediate sensitive results in 21.4% strains. Isolates of Pseudomonas spp. also showed very high sensitive results to aztreonam, ceftazidime and ceftriaxone (94.7%, 94.7% and 84.2% respectively). Ciprofloxacin and gentamicin were sensitive in 68.4% and 57.9% respectively. Susceptibility pattern showed well correlation with clinical response in infected cases.

Bacteria, Aerobic↗
PubMed2003

[Antimicrobial resistance of Escherichia coli isolates collected from inpatients and outpatients].

OBJECTIVE: To investigate the antimicrobial resistance of Escherichia coli (E. coli) isolates collected from the inpatients in the departments of medicine, surgery, and pediatrics, and intensive care unit (ICU), and from the outpatients. METHODS: Disc diffusion test was used to study the antimicrobial resistance of 3909 strains of E. coli collected from the inpatients in the departments of medicine, surgery, and pediatrics, and Intensive care unit (ICU), and from the outpatients, mostly isolated from urine, sputum, blood, and different secreta in the year 2001. WHONET 5 software was used for analysis of the antimicrobial resistance; and significant differences were tested by chi(2) to compare the resistance rates to antibiotics. RESULTS: The incidences of extended-spectrum beta-lactamases producing strains were 11.2% (195/1737), 14.3% (141/983), 17.7% (28/158), 19.7% (24/122) and 8.4% (76/909) in the strains of E. coli isolated from the inpatients in the departments of medicine, surgery, and pediatrics, and ICU and from the outpatients respectively, with a detectable rate among the outpatients significantly lower than that among the inpatients (P < 0.005), and a detectable rate among the inpatients in the department of medicine significantly lower than those among the inpatients in the department of pediatrics and ICU (both P < 0.05). The resistance rates to cefazolin, cefotaxime, gentamicin and aztreonam of the isolates from the outpatients were significantly lower than those of the inpatients (all P < 0.05). The resistance rates to amoxicillin/clavulanic acid, ceftazidime, cefepime and amikacin of the isolates from the outpatients were significantly lower than those of the inpatients in the department of surgery and ICU (all P < 0.05); The resistance rates to ciprofloxacin and trimethoprim/sulfamethoxazole of the isolates from the outpatients were significantly lower than those from the ICU patients (both P < 0.05). The resistance rates to cefazolin and cefotaxime of E. coli isolates collected from the inpatients in the department of medicine were significantly lower than those of the isolates from the department of surgery and ICU (all P < 0.01); the resistance rates to gentamicin of the isolates from the department was significantly lower than that of the isolates from the department of surgery (P < 0.05). The resistance rates to amoxicillin/clavulanic acid and aztreonam of the isolates from the department of medicine were significantly lower than those of the isolates from the ICU (both P < 0.05). The resistance rate to ciprofloxacin of isolates from the inpatients in the department of pediatrics was significantly lower than that of the other isolates (all P < 0.01). CONCLUSIONS: It is of guiding significance for empirical use of antimicrobial agents in clinic to study on the resistant rates of the strains of E. coli isolated from different departments in hospital.

Drug Resistance, Bacterial↗
PubMed1992

Pseudomonas aeruginosa isolated from corneal ulcer: susceptibility to antimicrobial agents tested alone or in combination.

Twenty-eight isolates of P. aeruginosa from corneal ulcers were tested for their susceptibility to 19 antimicrobial agents by an agar dilution method. The effect of a combination of an aminoglycoside with a beta-lactam, ciprofloxacin or colistin was checked by the checkerboard titration method. The minimal inhibitory concentrations (MICs) of these antimicrobial agents varied greatly. The MICs of aminoglycosides were near the breakpoint value of the usual susceptibility definition in most tested strains, but some were highly resistant. Ciprofloxacin, imipenem, aztreonam, ceftazidime, cefoperazone, piperacillin and colistin were other effective drugs with low MICs. Piperacillin, ceftazidime or aztreonam in combination with gentamicin or amikacin revealed a synergistic effect, but antagonism was found with ciprofloxacin or colistin combined with gentamicin or amikacin. Considering the difference in drug concentration achievable between systemic administration and topical application, the MIC quantitative determinations and the combination effect of antimicrobial agents against ocular isolates could provide useful information to ophthalmologists in choosing drugs for treatment of P. aeruginosa ocular infections.

Amikacin↗
PubMed2003

[Antimicrobial susceptibility of Pseudomonas aeruginosa clinical isolates in Murcia, Spain].

The source and antimicrobial susceptibility of 1293 clinical isolates of Pseudomonas aeruginosa obtained from 1996 to 1999 were studied. Urine was the most common source for outpatient isolates (61.2%), while for hospitalized patients respiratory samples were the most frequent (40.2%). The most active antimicrobials with resistance rates <=10% were ceftazidime, imipenem, tobramycin and amikacin. By contrast, aztreonam, ciprofloxacin and gentamicin showed resistance levels >10%. The percentages of resistance to ceftazidime, aztreonam and imipenem in isolates from inpatients and from patients in the intensive care unit were significantly higher than those in isolates from outpatients and other clinical departments. Comparison of susceptibility data from 1996 to 1999 showed a significant increase in the resistance rate for all of the antibiotics studied but imipenem.

Anti-Bacterial Agents↗
PubMed2004

Phenotypic confirmation of extended-spectrum B-lactamases (ESBL) in clinical isolates of Escherichia coli and Klebsiella pneumoniae at the San Juan Veterans Affairs Medical Center.

Extended-spectrum Beta (beta)-lactamases (ESBLs) have emerged as an important mechanism of resistance to B-lactam antibiotics in gram-negative bacteria (GNB). They are enzymes that hydrolyze older B-lactam antibiotics as well as broad-spectrum cephalosporins and monobactams. ESBL producers have been reported in many bacteria but special attention has been paid to the ones in E.coli and Klebsiella spp. Detection of the ESBLs by the clinical laboratory is a special challenge. Surveillance to monitor resistance is important to decide when detection of ESBLs must be started. This study determined the prevalence of ESBL producers in the strains E.coli and K.pneumoniae at the San Juan VA Medical Center, and characterized their phenotypes to evaluate the importance to identify these bacteria as a standard routine procedure in the institution. All E.coli and K.pneumoniae isolated from Jan 1 to Mar 31, 2003 were evaluated according to National Committee for Clinical Laboratory Standards (NCCLS) screening criteria for suspected ESBL producers. Phenotypic confirmation of the ESBL production was performed using the Etest method. A total of 112/253 (44%) E.coli and 72/137 (53%) K.pneumoniae were identified as suspected ESBL producers. Etest was performed in 60% of the E.coli and 57% of the K.pneumoniae suspected to be ESBL producers. The overall ESBL prevalence for E.coli was 25% and in K.pneumoniae was 26%. Most E.coli ESBL-producers were from urine while the K.pneumoniae were from sputum. ESBL-producers were isolated from different sources including pleural and synovial fluids, blood, and skin besides urine and sputum. According to susceptibility results, the most reliable antibiotic in predicting a negative ESBL was cefpodoxime (CPD), and in the strains studied, the ESBL producers were consistently resistant to aztreonam (ATM). A large proportion (95%) of ESBL producing K.pneumoniae were susceptible to cefepime (CEP). Of the ESBL producing E.coli, 24% were susceptible. In the case of E.coli ESBLproducers, Cefepime can be considered as a therapeutic option if susceptibilities are available. Automated identification and sensitivity systems are valid alternatives for routine evaluation of B-lactam resistance but when increased resistance is documented in GNB and/or ESBL prevalence is high, ESBL detection should be performed. All confirmed ESBL producers should be reported resistant to all penicillins, cephalosporins, and aztreonam in spite of having susceptible ranges with routine susceptibility tests. Inappropriate antibiotic selection in infections caused by these organisms is associated with treatment failures, poor clinical outcomes, increased mortality and longer hospital stays.

Anti-Bacterial Agents↗