Israel Medical Association Journal

Background: Due to increasing antimicrobial resistance, there has been renewed interest in old drugs that have fallen into disuse because of toxic side effects. One such drug is chloramphenicol. Data on the use and susceptibility patterns to chloramphenicol in developed countries in recent years are limited.

Objectives: To assess the susceptibility of bacteria to chloramphenicol, and evaluate the use of chloramphenicol in Israeli hospitals as influenced by infectious disease specialists’ attitudes with regard to its potential harms.

Methods: A national survey was conducted in all Israeli hospitals. Questionnaires were sent to the directors of infectious disease units and included items on chloramphenicol susceptibility in clinical isolates, use of chloramphenicol for the treatment of inpatients, local recommendations for use of chloramphenicol, and concerns regarding side effects.

Results: Chloramphenicol is used in 83.3% of hospitals, mostly for the treatment of aspiration pneumonia. While 22.2% of infectious disease unit directors believe that chloramphenicol should be avoided because of dangerous side effects, 88.9% believe there is a place for chloramphenicol in the treatment of patients in this era of increasing antibiotic resistance. Chloramphenicol susceptibility is routinely assessed in 44.4% of hospitals, with high susceptibility rates found among gram-positive, gram-negative and anaerobic bacteria.

Conclusions: In an era of increasing antibiotic resistance, many Israeli infectious disease unit directors believe that chloramphenicol has a role in the treatment of respiratory tract and other infections in hospitalized patients.

Background: Streptococcus pneumoniae is now the predominant pathogen causing meningitis. The resistance of S. pneumoniae to penicillin and third-generation cephalosporins has grown steadily.

Objectives: To assess the antibiotic susceptibility of S. pneumoniae isolated from the cerebrospinal fluid of children with meningitis, and determine the antibiotic regimen appropriate for suspected bacterial meningitis in Israel.

Methods:  The study group included 31 children with 35 episodes of meningitis hospitalized from 1998 to 2006. S. pneumoniae isolates from the cerebrospinal fluid were tested for susceptibility to penicillin and ceftriaxone.

Results: Of the 35 isolates, 17 (48.6%) showed resistance to penicillin (minimum inhibitory concentration ≥ 0.12 µg/ml). Only 3 isolates (8.6%) showed intermediate resistance to ceftriaxone (≥ 0.5 and < 2 μg/ml), and none showed complete resistance (MIC[1] ≥ 2 μg/ml). The rates of antibiotic resistance were higher in children who were treated with antibiotics prior to admission (penicillin 88.9% vs. 34.6%, P = 0.007; ceftriaxone 22.2% vs. 3.8%, P = 0.156).

Conclusions:  The rate of penicillin resistance is high in children with S. pneumoniae meningitis in Israel, especially in those treated with oral antibiotics prior to admission. Resistance to ceftriaxone is infrequent though not negligible. On the basis of these findings, current recommendations to empirically treat all children with suspected bacterial meningitis with ceftriaxone in addition to vancomycin until the bacterial susceptibility results become available are justified also in Israel.

Objective: To examine the effect of aspirin administration (low dosage) on the susceptibility of LDL to oxidative modification healthy volunteers.

Methods: Aspirin 75 mg was administered daily for 2 weeks to 10 healthy volunteers selected from the medical staff and students at the faculty of medicine. The main outcome measure was ex vivo oxidation of LDL by ultraviolet C irradiation or by peroxyl free redicals generated by AAPH (2,2’ -azobis 2-amidinopropane hydrochloride). The extent of LDL oxidation was determined by measuring the formed amounts of thiobarbituric-acid reactive substances, lipid peroxides and conjugated dienes.

Results: Following exposure to UV_C irradiation there was a significant (p<0.01) increase (10.8%) in TBARS concentrations and a significant (p≤0.05) increase (5.4%) in PD concentrations in LDL withdrawn after aspirin treatment as compared to LDL withdrawn before aspirin treatment. Following incubation with AAPH there was a significant (p<0.05) increase (15%) in PD concentrations and a significant (p<0.05) reduction (10%) of the LDL oxidation lag time in LDL withdrawn after aspirin intake as compared to LDL withdrawn before aspirin treatment.

Conclusions: Aspirin treatment given to healthy volunteers at a dose of 75 mg/day increased the susceptibility of their plasma LDL to oxidative modification ex vivo. Our study provides, for the first time, in vivo evidence of pro-oxidative properties of aspirin already suggested by previous in vitro trials.

Background: Identification of pathogens and their susceptibility to antimicrobials is mandatory for successful empiric antibiotic treatment.

Objectives: To compare the clinical characteristics of patients with bacteremia, as well as the bacterial distribution and antimicrobial susceptibility in community, hospital and long-term care facilities during two periods (2001–2002 and 2005–2006).

Methods: The study was conducted at the HaEmek Medical Center, a community 500-bed teaching hospital in northern Israel serving a population of ~500,000 inhabitants. All episodes of bacteremia (n=1546) during two 2 year periods (2001–2 and 2005–6) were prospectively recorded, evaluated and compared (755 in 2001–2 and 791 in 2005–6).

Results: In both periods the urinary tract was the main port of entry in community and long-term care facility bacteremia, while the urinary tract – primary and catheter-related – were similar in frequency as sources of hospital bacteremia. Escherichia coli was the most frequent pathogen isolate. No significant changes in the frequency of methicillin-resistant Staphylococcus aureus and extended-spectrum beta-lactamase-producing bacteria were seen between the two 2 year periods (2001–2 and 2005–6). The susceptibility of non-ESBL[1]-producing E. coli decreased for some antibiotics while non-ESBL-producing Klebsiella pneumoniae susceptibility profile improved in the same period. A non-statistically significant trend of increased resistance in gram-negative isolates to quinolones, piperacillin and piperacillin-tazobactam was observed, but most isolates still remained highly susceptible to carbapenems. There was a small increase in mortality rate in hospital bacteremia during the second period.

Conclusions: Continuous surveillance is imperative for monitoring the local epidemiology and for developing local treatment guidelines.

Background: In an era of increasing antimicrobial resistance, knowledge of local antimicrobial susceptibility patterns of common uropathogens is essential for prudent empiric therapy of community-acquired urinary tract infections.

Objectives: To define antimicrobial susceptibility of Gram-negative uropathogens in northern Israel over a 10 year period and to compare it with antibiotic-use patterns in the same community.

Methods: We tested the susceptibility of all Gram-negative urinary isolates from outpatients at HaEmek Medical Center over the years 1995, 1999, 2002 and 2005 to common antimicrobial agents. MIC₉₀ of Escherichia coli to some of these agents was determined and antibiotic consumption data over the years 2000–2005 (DDD/1000/day) were obtained.

Results: We observed a rise in susceptibility rates of E. coli to amoxicillin-clavulanate, trimethoprim-sulfamethoxazole and nitrofurantoin and of other Gram-negative isolates to amoxicillin-clavulanate, ceftriaxone and cephalothin. Susceptibility rates of all Gram-negative uropathogens to ciprofloxacin decreased significantly. MIC₉₀ of E. coli for all drugs tested remained stable. There was a significant decrease in the use nitrofurantoin and TMP-SMX[1] and a significant increase in the use of ampicillin, cephalothin and ceftriaxone.

Conclusions: Antibiotic resistance patterns mostly remained unchanged or improved slightly. There was, however, a constant decrease in susceptibility of all Gram-negative uropathogens to ciprofloxacin. Antibiotic use patterns could not explain the changes seen in antibiotic susceptibility patterns.

Objectives: To test the in vitro activity of linezolid (oxazolidinone) and other antimicrobial agents against MRSA[1] isolates recovered from hospitalized patients.

Methods: We tested 150 MRSA isolates recovered from hospitalized patients. The minimal inhibitory concentration of vancomycin, teicoplanin, pristinamycin (quinupristin-dalforistin), and linezolid was determined by the Etest method. Susceptibility to other antibiotics was tested by the disk diffusion method.

Results: All isolates were sensitive to vancomycin, teicoplanin, pristinamycin, and linezolid. The MIC₉₀ was 2.0 mg/ml for vancomycin and teicoplanin (range 0.5–2.0 mg/ml and 0.125–2.0 mg/ml, respectively), and 0.5 mg/ml for pristinamycin and linezolid (range 0.125–0.75 mg/ml and 0.125–0.5 mg/m, respectively). Of the other antibiotics, fusidic acid showed the best in vitro activity, with 96.7% susceptibility, associated with trimethoprim/sulfamethoxazole (85.8%) and minocycline (84%). Penicillin was associated with the lowest susceptibility (1.3%), associated with ofloxacin (3%) and erythromycin (14%). An increase in the minimal inhibitory concentration value of vancomycin was associated with a significant decrease in resistance to TMP-SMZ[2] (P < 0.01) and an apparent increase in resistance to other antibiotics.

Conclusion: The excellent in vitro activity of linezolid and its reported in vivo effectiveness renders it an important therapeutic alternative to vancomycin in the treatment of MRSA infection.

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[1] MRSA = methicillin-resistant Staphylococcus aureus

[2] TMP-SMX = trimethoprim/sulfamethoxazole

Background: Urinary tract infection is one of the most common bacterial infections. Since antibiotics are given empirically, it is necessary to assess the distribution and susceptibility of the microorganisms in each case.

Objectives: To evaluate the demographic characteristics of ambulatory patients with UTI, the distribution and susceptibility of uropathogens, and the risk factors associated with trimethoprim-sulfamethoxazole resistant bacteria in women.

Methods: During 12 days in August 1997 all the urine cultures sent to the Tel-Hanan Laboratory (Haifa) were evaluated. Demographic characteristics of the patients, their underlying diseases and the previous use of antibiotics were obtained.

Results: During the 12 day survey 6,495 cultures were sent for evaluation. Of the 1,075 (17%) that were positive 950 were included in the study; 83.7% were from females, of whom 57% were ≥50 years old. Escherichia coli was the most common pathogen, with 74.7% in the female and 55% in the male population; 86.2% of the E. coli were resistant to amoxicillin, 38.8% to cephalexin and 46.8% to TMP-SMX. Cefuroxime (4.2%), ofloxacin (4.8%), ciprofloxacin (4.8%) and nitrofurantoin (0.4%) showed the lowest rates of resistance. By a multivariant analysis, post-menopause and recurrent UTI were found to be independent factors related to TMP-SMX resistance in women.

Conclusion: In northern Israel, ampicillin, cephalexin and TMP-SMX cannot be used empirically in the treatment of community-acquired UTI. Post-menopause and recurrent UTI are independent factors associated with TMP-SMX resistant pathogens in women.

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UTI= urinary tract infection

TMP-SMX= trimethoprim-sulfamethoxazole