Antimicrobial Resistance of Gram-Negative Isolates from Intensive Care Units in Turkey: Comparison to Previous Three Years

Abstract

Resistance rates to selected antibiotics of Gram-negative bacteria isolated from intensive care units (ICU) of 16 Turkish hospitals during 1998 were evaluated and compared to data from the previous 3 years. Antibiotic susceptibilities to imipenem, ceftazidime, ceftazidime-clavulanate, cefoperazone-sulbactam, ceftriaxone, cefepime, cefodizime, cefuroxime, piperacillin-tazobactam, ticar-cillin-clavulanate, gentamicin, amikacin and ciprofloxacin were determined by Etest. A total of 1,404 isolates from 1,060 patients were collected, mainly from urinary and respiratory tracts. As in the previous 3 years, Pseudomonas spp. was the most frequently isolated Gram-negative species (29.7%), followed by Escherichia coli, Acinetobacter and Klebsiella spp. Imipenem was the most active in vitro agent (73.4% susceptible), followed by ciprofloxacin (60.6%), cefoperazone-sulbactam (58.7%), cefepime (56.7%), piperacillin-tazobactam (55.0%) and amikacin (54.7%). In 1996, a decline in susceptibility rates of all antibiotics was evident. With the exception of imipenem, resistance to which remained stable, rates somewhat increased in 1997. In 1998, susceptibility to imipenem and cefepime remained stable, amikacin resistance tended to increase and susceptibility rates to other antibacterials showed a favorable increase. These results may in part be due to the implementation of a surveillance program and increased understanding of the magnitude of the resistance problem.     

Surveillance of antimicrobial resistance in gram-negative isolates from intensive care units in Turkey: analysis of data from the last 5 years

A multicenter antimicrobial surveillance program was established in Turkey in 1995 to monitor the predominant Gram-negative pathogens from intensive care units (ICUs) and antimicrobial resistance patterns of these isolates. Sixteen hospitals participated in the study and a total of 1479 isolates from 1,100 patients were collected. The isolates were tested for their susceptibility against 13 antibiotics by E-test method. Minimum inhibitory concentrations (MICs) for each isolate were determined for imipenem, ceftazidime, ceftazidime-clavulanate, cefoperazone-sulbactam, ceftriaxone, cefepime, cefuroxime, piperacillin-tazobactam, ticarcillin-clavulanate, gentamicin, amikacin and ciprofloxacin. The most common isolates were Pseudomonas spp. (28.2%), Escherichia coli (19.2%) and Klebsiella spp. (19.1%). We found very high resistance rates to all major antibiotics that are used to treat serious infections. Although imipenem is the most active agent, it had an overall susceptibility rate of 68%. Half of the tested Klebsiella spp. strains were found to produce ESBL. This is a very high rate when compared with the literature. Cross-resistance among species was also investigated. 52% of ciprofloxacin-resistant strains were also resistant to imipenem, 80% to ceftazidime, 97% to ceftriaxone, 86% to amikacin and 19% of imipenem-resistant strains were susceptible to ceftazidime and 18% to amikacin. When susceptibilities of the years 1995 and 1999 were compared, the most interesting finding was the decrease in resistance to 3rd generation cephalosporins. In conclusion, this national clinical isolate database shows that resistance rates are high, the change over years is not predictable and continuous surveillance is necessary to monitor antimicrobial resistance and to guide antibacterial therapy.     

In vitro synergy and selection of resistance by fluoroquinolones plus amikacin or beta-lactams against extended-spectrum beta-lactamase-producing Escherichia coli

This study compared the potential synergy of levofloxacin and ciprofloxacin in combination with cefepime, ceftazidime, imipenem, piperacillin/tazobactam or amikacin, against extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli by using checkerboard and time kill studies. Moreover, selection of resistance was determined by frequency of mutations and by calculating the increase in minimum inhibitory concentrations (MICs) after five serial subcultures on antibiotic-containing plates. Synergy occurred more often with levofloxacin combined with imipenem (7/10 strains) and with levofloxacin or ciprofloxacin with amikacin (10/10) than for the other combinations. Time kill studies showed synergy for levofloxacin combined with amikacin, ceftazidime, imipenem or piperacillin/tazobactam, and for ciprofloxacin combined with amikacin, cefepime or imipenem. Antibiotic combinations selected for resistance less frequently than antibiotics alone. Mutation frequency was <10(-12) for all combinations. In conclusion, the combination of a fluoroquinolone with a beta-lactam or amikacin may provide improved antimicrobial activity and help limit the occurrence of resistance in ESBL-producing E. coli strains.     

Antimicrobial Susceptibility Patterns in Pseudomonas aeruginosa:Data from a Multicenter Intensive Care Unit Surveillance Study (ISS) in the United States

Abstract

The objectives of this study were to analyze susceptibility rates and patterns in Pseudomonas aeruginosa isolates from patients in intensive care units (ICU). A total of 2209 isolates in 1995/1996 and 2672 in 2001/2002 were tested at United States sites participating in the ICU Surveillance Study. In both periods, of the agents tested, amikacin was the most active and ciprofloxacin, the least. Resistance to common antipseudomonal agents tested increased from 1995/1996 to 2001/2002; the rise was least for amikacin (2%) and greatest for ciprofloxacin (16%). The proportion of isolates susceptible to all six antipseudomonal agents tested since 1996 decreased from 60.4% to 48.9% in 2001/2002. Examination of MIC distributions for the two periods showed that for some drugs, e.g. imipenem and ceftazidime, the populations of susceptible and resistant isolates remained distinct, although the resistant population increased. For other drugs, e.g. amikacin and piperacillin-tazobactam, the MIC distribution shifted upward over time. The categorical agreement between agents of the same or like classes for isolates tested in 2001/2002 was highest for ciprofloxacin and levofloxacin (93.2%, with 1.2% major errors) and lowest for the aminoglycosides (81.3%, with 10.2% major errors). We can conclude that resistance to antipseudomonal agents among ICU isolates of P. aeruginosa, especially fluoroquinolones, is increasing. The resistance rate for some antipseudomonal agents may not accurately reflect shifts in the MIC distribution curve.     

Antimicrobial susceptibility patterns in Pseudomonas aeruginosa: data from a multicenter Intensive Care Unit Surveillance Study (ISS) in the United States

The objectives of this study were to analyze susceptibility rates and patterns in Pseudomonas aeruginosa isolates from patients in intensive care units (ICU). A total of 2209 isolates in 1995/1996 and 2672 in 2001/2002 were tested at United States sites participating in the ICU Surveillance Study. In both periods, of the agents tested, amikacin was the most active and ciprofloxacin, the least. Resistance to common antipseudomonal agents tested increased from 1995/1996 to 2001/2002; the rise was least for amikacin (2%) and greatest for ciprofloxacin (16%). The proportion of isolates susceptible to all six antipseudomonal agents tested since 1996 decreased from 60.4% to 48.9% in 2001/2002. Examination of MIC distributions for the two periods showed that for some drugs, e.g. imipenem and ceftazidime, the populations of susceptible and resistant isolates remained distinct, although the resistant population increased. For other drugs, e.g. amikacin and piperacillin-tazobactam, the MIC distribution shifted upward over time. The categorical agreement between agents of the same or like classes for isolates tested in 2001/2002 was highest for ciprofloxacin and levofloxacin (93.2%, with 1.2% major errors) and lowest for the aminoglycosides (81.3%, with 10.2% major errors). We can conclude that resistance to antipseudomonal agents among ICU isolates of P. aeruginosa, especially fluoroquinolones, is increasing. The resistance rate for some antipseudomonal agents may not accurately reflect shifts in the MIC distribution curve.     

Widespread detection of VEB-1-type extended-spectrum beta-lactamases among nosocomial ceftazidime-resistant Pseudomonas aeruginosa isolates in Sofia, Bulgaria

A total of 132 ceftazidime-resistant clinical isolates of Pseudomonas aeruginosa were collected during 2001-2005 from 5 university hospitals in Sofia, Bulgaria to assess the current levels of antimicrobial susceptibility and to evaluate resistance mechanisms to beta-lactams. Antimicrobial susceptibilities were detected by a disk diffusion method and E-test. Polymerase chain reaction amplification and sequencing of bla(VEB-1 )and bla(PER-1 )were performed. The antibiotic resistance rates were: to piperacillin 90.2%, piperacillin/tazobactam 52.3%, ceftazidime 94.7%, cefepime 88.6%, cefpirome 98.5%, aztreonam 85.6%, imipenem 66.6%, meropenem 63.6%, amikacin 81.1%, gentamicin 84.8%, tobramycin 89.4%, netilmicin 57.6%, ciprofloxacin 83.4%. Structural genes for VEB-1 extended-spectrum beta -lactamases (ESBLs) were found in 75 (56.8%) of the isolates. PER-1 ESBLs were not detected. The VEB-1-producing strains were more resistant than VEB-1 non-producers to amikacin, gentamicin, tobramycin and ciprofloxacin ( P<0.001). VEB-1 appears to have a significant presence among ceftazidime-resistant P. aeruginosa isolates from Sofia.     

A survey of antimicrobial drug resistance in respiratory tract pathogens,isolated in a northern Italian teaching hospital between 1990 and 1999

Drug susceptibility test results of respiratory tract pathogens, isolated from patients admitted to the Clinic of Respiratory Diseases of the IRCCS San Matteo Hospital, University of Pavia (Italy) between 1990 and 1999, were retrospectively evaluated. A total of 1366 bacterial isolates were collected, including 499 gram-positive and 867 gram-negative strains. In comparison to methicillin-susceptible Staphylococcus aureus, the methicillin-resistant strains (MRSA) showed high levels of resistance to many selected antibiotics, except for glycopeptides. Resistance rates to beta-lactams were high in both Pseudomonas aeruginosa and in the other gram-negative isolates, while aminoglycoside and ciprofloxacin resistance was less than 20%. Some pathogens became more resistant to selected antimicrobials during the observation period, including staphylococci to methicillin, MRSA to ciprofloxacin, P. aeruginosa isolates to imipenem and ciprofloxacin, and the other gram-negative strains to almost all drugs considered, with the exception of cefotaxime and cotrimoxazole.     

Comparative antimicrobial potency of meropenem tested against Gram-negative bacilli: report from the MYSTIC surveillance program in the United States (2004)

The Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program is a longitudinal resistance surveillance network of more than 100 medical centers worldwide monitoring the susceptibility of bacterial pathogens to carbapenems and other broad-spectrum agents. In 2004 (year six), the antimicrobial activity of 12 broad-spectrum agents was assessed against 2,799 Gram-negative bacterial isolates submitted from 15 United States (USA) medical centers using Clinical and Laboratory Standards Institute (CLSI; formerly NCCLS) recommended methods. Meropenem continued to demonstrate a high potency with MIC90 values 4- to 32-fold lower than imipenem against the Enterobacteriaceae. The wide spectrum of activity for meropenem against all Gram-negative isolates was demonstrated by the overall rank order of percentage susceptibility at CLSI breakpoints: amikacin (96.5%) > meropenem (96.0%) > imipenem (95.8%) > piperacillin/tazobactam (91.5%) > tobramycin (91.4%) > cefepime (91.2%) > ceftazidime (89.0%) > gentamicin (88.0%) > aztreonam (81.5%) > levofloxacin (80.5%) > ciprofloxacin (80.2%) > ceftriaxone (69.1%). Only the aminoglycosides (84.5%) and carbapenems (76.1-83.8%) exhibited acceptable levels of susceptibility against the Acinetobacter spp. isolates as this species group became more resistant to all antimicrobial classes. A continued increase in the resistance rate for both ciprofloxacin and levofloxacin over the six years was observed, most alarming among Escherichia coli (20.2-20.7%) and indole-positive Proteus species (34.4-42.2%) isolates, some documented as clonal. Continued surveillance of these broad-spectrum antimicrobial agents appears warranted to monitor the potency and spectrum of activity against Gram-negative pathogens causing serious infections and the emergence of new or novel resistance mechanisms that could compromise carbapenem therapy.     

Antimicrobial Resistance in Gram-Negative Hospital Isolates: Results of the Turkish HITIT-2 Surveillance Study of 2007

Abstract

Resistance rates to amikacin, ciprofloxacin, ceftazidime, cefepime, imipenem, cefoperazone/sulbactam and piperacillin/tazobactam in Escherichia coli (n= 438)Klebsiella pneumoniae (n= 444)Pseudomonas aeruginosa (n= 210) and Acinetobacterbaumanni (n=200) were determined with e-test in a multicenter surveillance study (HITIT-2) in 2007. ESBL production in Escherichia coli and K. pneumoniae was investigated following the CLSI guidelines. Overall 42.0% of E.coli and 41.4% of K. pneumoniae were ESBL producers. In E. coli, resistance to imipenem was not observed, resistance to ciprofloxacin and amikacin was 58.0% and 5.5% respectively. In K. pneumoniae resistance to imipenem, ciprofloxacin and amikacin was 3.1%, 17.8% 12.4% respectively. In P. aeruginosa the lowest rate of resistance was observed with piperacillin/tazobactam (18.1%). A. baumanni isolates were highly resistant to all the antimicrobial agents, the lowest level of resistance was observed against cefoperazone/sulbactam (52.0%) followed by imipenem (55.5%). This study showed that resistance rates to antimicrobials are high in nosocomial isolates and show variations among the centers.     

Antibiotic susceptibility tests directly on urine samples using Uro-Quick, a rapid automated system

During the period June 2003-March 2004, 12,579 urine samples were examined employing the Uro-Quick system. Positive samples (1,948) were subsequently Gram-stained and processed by standard procedures for microorganism identification and antibiotic susceptibility determination by the disk diffusion method. Results of this latter test were compared with those obtained employing the new rapid Uro-Quick method. Antibiotics were introduced in vials containing 2 ml of Mueller-Hinton broth, then 0.5 ml of urine or a bacterial suspension in broth were added; a vial without drug was used as control. After 3 and 5 hours of incubation (for Gram-negative and Gram-positive strains respectively) the instrument showed the results. No growth and a growth curve like the control indicated susceptible and resistant strains respectively. Overall 1,590 Gram-negative strains were tested against ciprofloxacin, nitrofurantoin, amoxicillin-clavulanate, ceftazidime, fosfomycin, imipenem, amikacin, trimethoprim-sulfamethoxazole, and piperacillin-tazobactam, while 358 Gram-positive bacteria were assessed against ciprofloxacin, nitrofurantoin, amoxicillin-clavulanate, ampicillin, fosfomycin, gentamicin, oxacillin and trimethoprim-sulfamethoxazole. Against the major urinary tract pathogens (Escherichia. coli, enterococci, Klebsiella spp. and Proteus spp.) agreement between the Uro-Quick system and the disk diffusion test generally was >90% for all antibiotics tested. On the basis of these results the system appears useful not only for bacteriuria screening, but also to rapidly test the antibiotic susceptibility of common uropathogens.     

Gram-negative bacterial resistance to cephalosporins in community-acquired infections in Turkey

Cephalosporins are widely used and trustworthy antibiotics in daily medical practice. Although antibacterial resistance has been reported in hospital wards, there are less data for community-acquired infections. In this study we investigated the cephalosporin susceptibility profiles of community-acquired Gram-negative bacteria isolates in Sivas Kizilay Medical Center (Turkey) between March 2002 and March 2003. In our study, 949 Escherichia coli, 165 Proteus spp., 97 Enterobacter spp., 24 Klebsiella spp and 84 Pseudomonas aeruginosa strains were evaluated. Cefepime seemed to be the most effective antibiotic against our community-acquired Gram-negative isolates. Resistance to this drug was 19.3% for P. aeruginosa and around 0-10.6% for enteric bacteria. Enteric pathogen resistance ranged between 44.3-100% for cefazolin, 25-51.9% for cefuroxime, 4.8-25.3% for ceftriaxone, 5.4-14.5% for ceftazidime. Resistance in enteric pathogens to gentamicin ranged between 5.8-15.4%, to amikacin between 3.8-6.25%, to ciprofloxacin between 6.7-20%. 8.1% of P. aeruginosa were resistant to ciprofloxacin. With these profiles the aminoglycosides and ciprofloxacin resemble highly effective cephalosporins like cefepime. On the contrary, first- and second-generation cephalosporins, trimethoprim-sulfamethoxazole, ampicillin and ampicillin-sulbactam are no longer used in probable Gram-negative bacterial infections in our region. Since treatment based on cephalosporins was less efficacious than expected in community-acquired infections, urgent measures are needed to limit antibacterial resistance outside of hospitals.     

Antibiotic resistance among nosocomial isolates in a Croatian intensive care unit--results of a twelve-year focal surveillance of nosocomial infections

Continuous 12-year (1990--2001) focal surveillance of the antibiotic resistance among the most common nosocomial pathogens (Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter sp., and Staphylococcus aureus) in 1325 Intensive Care Unit patients was performed. The surveillance period was divided in three 4-year time intervals (1990--1993, 1994--1997 and 1998--2001) and the prevalence of resistance was compared between intervals. Specimens included blood, urine and respiratory tract specimens. The incidence and trends of resistance to six antibiotics showed inconsistent results. Aminoglycoside resistance decreased among K. pneumoniae_isolates (gentamicin 83%, 72.7% and 49.6%; amikacin 50.9%, 51.5% and 18.2%) and Acinetobacter sp. strains (amikacin 77%, 63.4% and 58.2%) but increased in P. aeruginosa (amikacin 27.5%, 63.3% and 44.1%). Overall, resistance to ceftazidime, ciprofloxacin, and imipenem increased but imipenem resistance is still low, particularly among Acinetobacter sp. isolates (0, 2.1% and 1.5%). However, imipenem resistance increased among P. aeruginosa (10.2%, 31.6%, 22.1%). The prevalence of methicillin resistance was high but did not change during the surveillance period (82.3%, 78.3% and 82.2%). The present study suggests a complex picture of the development of antibiotic resistance in a single ICU. Significant changes occur over time but they are unpredictable and do not show identical tendencies for different species and antibiotics.     

Treatment of febrile neutropenic patients with cancer who require hospitalization: a prospective randomized study comparing imipenem and cefepime

BACKGROUND: The objective of the current study was to compare the efficacy and safety of imipenem and cefepime in the treatment of adult patients with cancer who had fever and neutropenia requiring hospitalization according to Infectious Disease Society of America criteria. METHODS: In the current prospective randomized clinical trial at a university-affiliated tertiary cancer center, adult patients with cancer who had fever (> or = 38.3 degrees C or > or = 38.0 degrees C for > 2 hours) and neutropenia (< or = 500/mm(3) or < 1000/mm(3) but declining) requiring hospitalization were randomized to receive either cefepime or imipenem. Vancomycin or amikacin was added on suspicion of gram-positive or gram-negative bacterial infection, respectively. RESULTS: Patients who received an imipenem regimen or a cefepime regimen were comparable in terms of age, gender, underlying malignancy, prior transplantation, degree and trend of neutropenia, and presence of central venous catheters (P > or = 0.3). An intent-to-treat analysis showed a 68% response rate to the imipenem regimen, compared with a 75% response rate to the cefepime regimen (P = 0.2). The rates of antibiotic-related adverse events and superinfections also were comparable (P = 0.6). There was no difference in response among patients who received imipenem or cefepime alone compared with patients who also received vancomycin or amikacin (P = 1.0). Leukemia was the only independent risk factor associated with a poor outcome (odds ratio, 4.6; 95% confidence interval, 1.9-10.7; P < 0.0001). CONCLUSIONS: Imipenem and cefepime had similar efficacy and safety profiles in the treatment of adult cancer patients with fever and neutropenia who required hospitalization. The addition of either vancomycin or amikacin may not be necessary.     

Epidemiology of antibiotic resistance in human isolates of Enterobacteriaceae in Sicily

The authors have studied the antimicrobial susceptibility of 1073 clinical isolates of various genera of Enterobacteriaceae (collected during the period July-December 1988) to ampicillin, piperacillin, cefotaxime, ceftazidime, ceftriaxone, aztreonam, imipenem, gentamicin, amikacin, netilmicin, norfloxacin, and ciprofloxacin. Antimicrobial susceptibility was determined by Bauer-Kirby disk diffusion method. Of 1073 tested bacteria, 704 (65.6%) produced beta-lactamase detectable by nitrocefin test. The highest percentage of resistant strains occurred with ampicillin (70%) followed by piperacillin (24%) and cefotaxime (19%). Lower percentages of resistant strains were found for gentamicin (10%), aztreonam (8%), netilmicin (7%), norfloxacin (5%) and amikacin (4%). Two percent of the strains were resistant to ciprofloxacin and 0.5% to imipenem. The incidence of resistance in Klebsiella sp., Enterobacter sp., E. coli and Proteus sp. was compared to that found among 872 strains isolated during July-Dec. 1984. In all the Enterobacteriaceae, mainly Enterobacter sp., the increase in the resistance was high for ampicillin, piperacillin and cefotaxime and lower for gentamicin.     

Antimicrobial use and resistance among Gram-negative bacilli in an Italian intensive care unit (ICU)

Gram-negative bacilli antimicrobial resistance remains a significant problem for patients in the intensive care unit (ICU). We performed a retrospective analysis of microbiological data and antibiotic consumption over a 4-year period (2000-2003) in an Italian ICU. Pseudomonas aeruginosa and Klebsiella pneumoniae represented approximately 40% of all isolates. The most significant trend in antimicrobial use was an increase in use of 3(rd )generation cephalosporins, imipenem, and ciprofloxacin. A significant trend toward an increase in resistance rates to piperacillin, 3( rd )generation cephalosporins and ciprofloxacin was observed for K. pneumoniae and a positive correlation between resistance and drug-usage was evident for K. pneumoniae and piperacillin, cefotaxime, ceftazidime, cefepime, and ciprofloxacin, but not for piperacillin/tazobactam. No statistically significant correlations were evidenced for P. aeruginosa. Trends in resistances were studied also for Serratia spp and Proteus spp. Isolation rates of extended-spectrum beta-lactamase (ESBL)-producing strains in pathogens studied were high, especially for K. pneumoniae (72%, 160/222) and Proteus spp (41%, 18/43). In conclusion, the study showed high resistance among Gram-negative organisms isolated in the ICU and significant ESBL production. A significant correlation between antibiotic consumption and increasing resistance was evident for K. pneumoniae.     

Antibiotic Resistance Among Nosocomial Isolates in a Croatian Intensive Care Unit - Results of a Twelve-Year Focal Surveillance of Nosocomial Infections

Abstract

Continuous 12-year (1990-2001) focal surveillance of the antibiotic resistance among the most common nosocomial pathogens (Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter sp. and Staphylococcus aureus) in 1325 Intensive Care Unit patients was performed. The surveillance period was divided in three 4-year time intervals (1990-1993, 1994-1997 and 1998-2001) and the prevalence of resistance was compared between intervals. Specimens included blood, urine and respiratory tract specimens. The incidence and trends of resistance to six antibiotics showed inconsistent results. Aminoglycoside resistance decreased among K. pneumoniae isolates (gentamicin 83%, 72.7% and 49.6%; amikacin 50.9%, 51.5% and 18.2%) and Acinetobacter sp. strains (amikacin 77%, 63.4% and 58.2%) but increased in P. aeruginosa (amikacin 27.5%, 63.3% and 44.1%). Overall, resistance to ceftazidime, ciprofloxacin, and imipenem increased but imipenem resistance is still low, particularly among Acinetobacter sp. Isolates (0, 2.1% and 1.5%). However, imipenem resistance increased among P. aeruginosa (10.2%, 31.6%, 22.1%). The prevalence of methicillin resistance was high but did not change during the surveillance period (82.3%, 78.3% and 82.2%). The present study suggests a complex picture of the development of antibiotic resistance in a single ICU. Significant changes occur over time but they are unpredictable and do not show identical tendencies for different species and antibiotics.     

Common antimicrobial resistance patterns, biotypes and serotypes found among Pseudomonas aeruginosa isolates from patient's stools and drinking water sources in Jordan

Pseudomonas aeruginosa was isolated in low rates from stool specimens of outpatients and inpatients (7% versus 12%) but in higher rates from chlorinated and nonchlorinated water sources (15% versus 44%), respectively in Jordan. The same biotype was recognized among 90% of P. aeruginosa isolates from patient's stools and water sources using specific biochemical profiles. Three serogroups belonging to 01, 06 and 011 accounted for the majority of these isolates in water (66%) and stools (78%), respectively. All P. aeruginosa isolates from water were highly susceptible (87%-100%) to piperacillin-tazobactam, amikacin, gentamicin, imipenem, aztreonam, ceftazidime and ciprofloxacin, whereas the isolates from stool were slightly less susceptible (81%-98%) to these antimicrobials. P. aeruginosa isolates from water and stool sources were almost equally highly resistant to tetracycline (86%-89%) and carbenicillin (88%-89%), respectively. One common small plasmid (15.4 kb) was detected in 14/25 (56%) of multidrug-resistant P. aeruginosa isolates from both water and stool. This study demonstrates certain common epidemiological characteristics including antimicrobial resistance pattern, biotypes and serotypes among P. aeruginosa isolates from patient's stools and drinking water sources in Jordan.     

Epidemiology of Antibiotic Resistance in Human Isolates of Enterobacteriaceae in Sicily

Summary

The Authors have studied the antimicrobial susceptibility of 1073 clinical isolates of various genera of Enterobacteriaceae (collected during the period July-December 1988) to ampicillin, piperacillin, cefotaxime, ceftazidime, ceftriaxone, aztreonam, imipenem, gentamicin, amikacin, netilmicin, norfloxacin, and ciprofloxacin.

Antimicrobial susceptibility was determined by Bauer--Kirby disk diffusion method. Of 1073 tested bacteria, 704 (65.6%) produced beta-lactamase detectable by nitrocefin test. The highest percentage of resistant strains occurred with ampicillin (70%) followed by piperacillin (24%) and cefotaxime (19%). Lower percentages of resistant strains were found for gentamicin (10%), aztreonam (8%), netilmicin (7%), norfloxacin (5%) and amikacin (4%). Two percent of the strains were resistant to ciprofloxacin and 0.5% to imipenem.

The incidence of resistance in Klebsiella sp., Entero-bacter sp., E.coli and Proteus sp. was compared to that found among 872 strains isolated during July-Dec. 1984. In all the Enterobacteriaceae, mainly Enterobacter sp., the increase in the resistance was high for ampicillin, piperacillin and cefotaxime and lower for gentamicin.     

Bacterial susceptibilities to piperacillin/tazobactam in a tertiary care hospital: 5-year review

Several factors influence the speed of development of antibacterial resistance, among which is the amount of antibiotic consumption. During the 3-year period 1998-2000, the consumption of piperacillin/tazobactam (pip/tazo) increased by 85% in our hospital. Five years ago we conducted a comparative in vitro study to evaluate susceptibilities of microorganisms to pip/tazo. The objective of the present study was to re-evaluate in vitro susceptibilities to pip/tazo, compared to other beta-lactams, and the potential impact its increased consumption might have on its susceptibility patterns. The study was performed between November 2000 and April 2001. As in 1996, of the beta-lactams studied, pip/tazo and imipenem had the highest susceptibility rates against selected pathogens (>90% susceptibility rates). P. aeruginosa susceptibilities to both imipenem and pip/tazo were high (97% for both). P. aeruginosa susceptibilities to cefepime were lower. Despite its increased use, pip/tazo retained its initially observed high susceptibility rates for the study pathogens.     

Bacteremia due to Pseudomonas aeruginosa: results from a 3-year national study in the Slovak Republic

Risk factors, mortality and antimicrobial susceptibility of Pseudomonas aeruginosa bacteremias isolated from 148 patients from all University Hospitals in Slovakia were analyzed. Only 1.2% of 169 strains of P. aeruginosa were resistant to meropenem, 4.1% to piperacillin/tazobactam, 7.7% to ceftazidime as well as cefepime and 12% to amikacin. More than 30% of P. aeruginosa were resistant to ciprofloxacin. Our analysis of risk factors for antimicrobial resistance to the particular antimicrobials, indicated no difference in risk factors and outcome in cases infected with P. aeruginosa bacteremias resistant to amikacin, piperacillin/tazobactam or ceftazidime in comparison to episodes caused by P. aeruginosa due to susceptible isolates. When comparing risk factors for P. aeruginosa bacteremia in children vs. adults, cancer vs. non-cancer patients, several differences in risk factors were observed. Neither antimicrobial resistance to amikacin, ceftazidime or piperacillin/tazobactam, nor appropriateness of therapy according to two separate analyses were associated with better outcome.