Susceptibility of 228 Non-fermenting Gram-Negative Rods to Tigecycline and Six Other Antimicrobial Drugs

Abstract

The aim of the study was to determine the in vitro activity of tigecycline and 6 other antimicrobial drugs used in clinical practice against 228 clinical isolates of nonfermenting Gram-negative rods (NFGNRs) including Acinetobacter spp. Stenotrophomonas maltophilia, and Pseudomonas aeruginosa. Minimum inhibitory concentrations (MICs) were determined according to the recommendations of the Clinical and laboratory Standards institute. For tigecycline, we used the criteria approved by the FDA. Almost 50% of the clinical isolates of Acinetobacter spp. were resistant to piperacillin/tazobactam, ciprofloxacin, gentamicin, and ceftazidime. Strains of this microorganism were more susceptible to imipenem, and even more susceptible to colistin and tigecycline; no strains were resistant to tigecycline. Stenotrophomonas maltophilia showed even greater resistance to the drugs tested. Thus, all strains were resistant to imipenem and a large percentage (82.6%) were resistant to piperacillin/tazobactam. Resistance to the other agents tested was also high, with the exception of tigecycline, with only 3 resistant strains (MIC <8 mg/ml). Tigecycline, on the other hand, was scarcely active against Pseudomonas aeruginosa, which bears efflux pump systems such as MexXY-OprM. Almost 90% of strains were resistant to ciprofloxacin; only 8% were resistant to gentamicin; over half were colistin-intermediate or -resistant, and finally, approximately half of the strains were susceptible to the 3 beta-lactams studied. In conclusion, NFGNRs present variable susceptibility patterns, although they are generally highly resistant to antimicrobial agents including those considered more specific. Tigecycline, which showed good activity against most of the strains examined, broadens the spectrum of drugs available for the treatment of infections caused by these complex microorganisms.     

Bacteremia Due to Pseudomonas aeruginosa: Results from a 3-Year National Study in the Slovak Republic

Abstract

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.     

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.     

Antibiotic Resistance of Bacteria Associated with Community-Acquired Urinary Tract Infections in the Southern Area of the Gaza Strip

Abstract

The aim of this study was to identify the microorganisms that cause “community-acquired” urinary tract infections among adults and to investigate their resistance to fourteen selected antimicrobial agents. The uropathogens identified in 121 positive midstream urine cultures from the 270 subjects included in this study were Escherichia coli (57.9%), Proteus species (9.9%), Enterobacter species (7.4%), Klebsiella species (6.6%), Pseudomonas species (5.8%), Staphylococcus saprophyticus (5.0%), Enterococcus species (3.3%), Acinetobacter species (2.5%), Citrobacter species (0.8%) and Staphylococcus aureus (0.8%). Isolates were subjected to antimicrobial susceptibility testing and a high proportion of the isolates was found to be resistant to amoxycillin (73.6%), doxycycline (68.6%) and trimethoprim-sulfamethoxazole (66.1%). The most effective drugs against all the isolates were ciprofloxacin (95.9%), amikacin (95.0%) and ceftazidime (94.2%). A high percentage of multiple-drug resistance was also observed for the majority of the isolates.     

An Observational Study on the Epidemiology of Respiratory Tract Bacterial Pathogens and Their Susceptibility to Four Injectable Beta-Lactam Antibiotics: Piperacillin,Piperacillin/Tazobactam,Ceftazidime and Ceftriaxone

Abstract

Bacterial infections of the respiratory tract account for a large proportion of total medical consultations in general practice. In recent years, antibiotic resistance has increased alarmingly in a number of bacterial species that are common causes of these infections. The aim of this observational study was to determine the antibiotic resistance of microbial agents isolated from patients with acute or acutely exacerbated respiratory infections. Subjects recruited as potential sources of bacteria were either outpatients seen in a number of specialized clinics and hospital practices, or hospitalized patients. Overall, 64-a8 consecutive patients (67% male, mean age 48.1 ± 27.0 years) with infection of the upper or lower respiratory tract were observed during a 13-month period. A total of 551 pathogenic microbial strains were isolated and tested for their in vitro susceptibility to piperacillin, piperacillin/tazobactam, ceftazidime, and ceftriaxone. Among all isolates, the four most frequent pathogens were Pseudomonas aeruginosa (132 isolates, 24%), Streptococcus pyogenes (99 isolates, 18%), Staphylococcus aureus (93 isolates, 17%), and Klebsiella pneumoniae (46 isolates, 8%). The susceptibility of Gram-positive isolates ranged from 97.5% to 95.1%, and no remarkable difference was found in the antibacterial activity of tested b-lactam antibiotics. The susceptibility of Gram-negative isolates to piperacillin and piperacillin/tazobactam was also similar: 96.5% and 97.1%, respectively. In contrast, differences were found between piperacillin (or piperacillin/tazobactam) and either ceftazidime (p=0.003) or ceftriaxone (p<0.0003) in Gram-negative isolates.

We conclude that, despite the extensive use of beta-lactam antibiotics (piperacillin, ceftazidime, and ceftriaxone) in medical practice during the past three decades, the susceptibility of the most common pathogens involved in the etiology of upper and lower respiratory tract infections to these antibiotics is still high. In particular, bacterial resistance developed by Gram-positive organisms against piperacillin is negligible and not alarming.     

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.     

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.     

Multi-drug-resistant Enterococcus faecalis among Egyptian patients with urinary tract infection

The prevalence of Enterococcus faecalis (E. faecalis) infections among Egyptians with urinary tract infection (UTI), their antimicrobial susceptibility and mechanisms of resistance are under investigated. In this study, 300 urine samples were collected from UTI patients to identify E. faecalis. Antimicrobial susceptibility to 18 antimicrobial agents was tested. The presence of aac(6)-Ie-aph(2)Ia, erm(B) and mef(A/E) genes was examined by PCR. Fifty-seven (19%) isolates were identified as E. faecalis. All isolates were sensitive to teicoplanin and were completely resistant to nalidixic acid, cefotaxime and cefadroxil. Multi-drug-resistant (MDR) was found to be 100% with 45 different antibiotypes. The aac(6)Ia-aph(2)Ia gene was found in 100 and 90% of the isolates resistant to gentamicin at concentrations of 120 and 10 μg, respectively. erm(B) and mef(A/E) genes were present in 92.5% (37/40) and 2.5% (1/40) of erythromycin-resistant isolates, respectively. We conclude that there is a high prevalence of E. faecalis in UTI cases with a 100% MDR rate indicating a serious problem in treating infections by this organism in Egypt.     

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.     

Molecular characterization of Ambler class A to D β-lactamases,ISAba1, and integrons reveals multidrug-resistant Acinetobacter spp. isolates in northeastern China

The prevalence of various Ambler class A to D β-lactamases, ISAba1, and class 1 and 2 integrons as well as the clonal relatedness in 105 Acinetobacter spp. isolates found in northeastern China was investigated. All 105 Acinetobacter spp. isolates were determined to be multidrug resistant (MDR), and the resistance rates to carbapenem agents were approximately 50%. PER, IMP, AmpC, and OXA-23 were found to be dominant β-lactamases belonging to different classes, respectively. This is the first report of the coexistence of bla_PER, bla_IMP, bla_AmpC, and bla_OXA-23-like genes in Acinetobacter spp. isolates from northeastern China. ISAba1 was found upstream of the bla_OXA-23-like gene in 87.8% (36/41) strains and upstream of the bla_OXA-51-like gene in 26.5% (13/49) strains. ISAba3–like element was found upstream of the bla_OXA-58-like gene in one bla_OXA-58-like-positive strain. The presence of IntI1 was detected in 63.8% (67/105) of the isolates and the most prevalent gene cassettes were aacA4, aadA1, and catB8. The highly prevalent isolates belong to international clonal lineage (ICL)-II. These results indicate that the wide horizontal and clonal spread of MDR Acinetobacter spp. isolates harbouring multiple β-lactamase genes has become a serious problem in northeastern China.     

Gram-Negative Non-Fermenting Bacteria from Food-Producing Animals are Low Risk for Hospital-Acquired Infections

Abstract

The aim of this study was to investigate possible indications of epidemiological relationships between Pseudomonas aeruginosa and Acinetobacter baumannii isolated from food-producing animals and those of clinical origin. Screening for P. aeruginosa and A. baumannii isolates from food-producing animals was carried out on 1381 samples. usceptibility testing and PCR amplification of resistance genes were determined. Isolate clonal relatedness was established by PFGE. Forty-one P. aeruginosa and 16 A. baumannii were detected. All P. aeruginosa isolates were sensitive to ciprofloxacin, ceftazidime and piperacillin/tazobactam and seven isolates had low-level imipenem resistance. All A. baumannii isolates were sensitive to imipenem, meropenem, ciprofloxacin and piperacillin/tazobactam but were resistant to ceftazidime. The imipenem-resistant P. aeruginosa and ceftazidime-resistant A. baumannii had different PFGE patterns compared to those of human origin. Based on the findings presented here, animal isolates were not multidrug resistant and they do belong to a different pool from those of humans.     

Surveillance for azoles resistance in Aspergillus spp. highlights a high number of amphotericin B‐resistant isolates

Aspergillus spp. are the most common invasive mould infection and are responsible for high mortality. Aspergillus fumigatus is currently of interest because resistance to azole antifungals has emerged. The Campinas University Hospital (HC ‐UNICAMP ) receives high‐risk patients susceptible to opportunistic infections but there have been no reports of resistant A. fumigatus . This study aimed to assess the susceptibility profile of Aspergillus isolates, specifically looking for azole resistance. ITS and β‐tubulin DNA sequencing was performed on 228 sequential clinical isolates. Broth microdilution susceptibility testing was performed for all isolates. A. fumigatus represented 74% of the isolates followed by Aspergillus flavus (12%). Nine A. fumigatus isolates from 9 different patients showed high MIC values to at least 1 azole, but cyp51A polymorphisms were detected in only 6 isolates and none correlated with known resistance mutations. The most troubling observation was that the minimum inhibitory concentration for amphotericin B was elevated (≥2 mg L^?1) in 87% of patients with A. flavus isolates and 43% with Aspergillus fumigatus isolates. Given that amphotericin B is used to treat azole‐resistant infections, these data highlight the need for continuous surveillance in Aspergillus for all antifungal resistance to implement correct treatment strategies for the management of these pathogens.     

High Frequency of Isolation of Antibiotic-Resistant Oral Viridans Streptococci from Children in Kuwait

Abstract

Antimicrobial resistance among the Viridans group of streptococci (VGS) has emerged as a hindrance to effective antibiotic therapy. Our objective was to evaluate the prevalence of antibiotic-resistant VGS in healthy children.

Plaque samples were collected from tooth and tongue surfaces of 102 healthy subjects. Serially diluted samples were inoculated onto BHI agar plates and Mitis Salivarius Agar (MSA) plates and incubated as appropriate. Representative colonies were identified to species level by standard methods. Susceptibility of the VGS was performed by determining the minimum inhibitory concentrations (MICs) of 11 antibiotics using Etest.

Of the 540 VGS isolates from both sites, 58% were from the tooth surfaces and 42% from the tongue. The most prevalent were S. salivarius (21.5%) and S. sanguis (16.3%). Imipenem and vancomycin had excellent activities. Resistance rates to trimethoprim, amoxicillin, piperacillin, erythromycin, cefuroxime and cephalothin, were 60.7, 40.8, 34.7, 32.6, 27.5 and 25.3%, respectively. Resistance rates to penicillin and clindamycin were 15.9% and 15.4%, respectively. The majority of the erythromycin-resistant isolates were from the tongue; 41% versus 29%. At the species level, 26% and 23% of S. salivarius and 23% and 14% of S. mutans from the tooth and tongue, respectively were resistant to penicillin.

The data show species-related and site-related variations in the susceptibility pattern and an emerging high prevalence of antibiotic-resistant VGS. The difference in the susceptibilities between the species underscores the importance of accurate identification and the need for surveillance of antimicrobial resistance among clinical isolates in our hospitals.     

A Survey of Antimicrobial Resistance in a Tertiary Referral Hospital in the United Arab Emirates

Abstract

Published data on antimicrobial resistance are lacking for the United Arab Emirates (UAE). Knowledge of local patterns of resistance is essential to optimize guidelines for empirical antimicrobial treatment. Awareness of susceptibility patterns in other parts of the world may be important for determining empirical antimicrobial therapy for travelers or patients transferred from abroad. Antibiograms from unique isolates of common hospital and community bacteria are described in a tertiary referral hospital in the UAE, which had no antimicrobial restrictions and limited resources. Antimicrobial resistance rates were unpredictable and were high for Gram-negative organisms, such as Escherichia coli, Shigella sonnei, Campylobacter spp, and also Streptococcus pneumoniae. In contrast, methicillin-resistant Staphylococcus aureus (MRSA) comprised less than 5% of S. aureus isolates and glycopeptide-resistant enterococci (GRE) were not detected during the surveillance period. Our results provide data on antimicrobial resistance for the UAE and highlight the need for resources for surveillance of antimicrobial resistance.     

Bacterial Isolates from Severe Infections and Their Antibiotic Susceptibility Patterns in Italy: a Nationwide Study in the Hospital Setting

Abstract

The most frequent agents of severe bacterial infections and their antibiotic susceptibility patterns were determined in patients admitted to 45 Italian hospitals over the years 2002-2003. The most common diagnoses were: sepsis (33.8%), pneumonia (9.4%), intravascular catheter-associated infections (9.3%) and ventilator- associated pneumonia (8.1%). Overall, 5115 bacterial isolates were identified from 4228 patients. Three bacterial species, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, accounted for more than 50% of the isolates. Other prevalent bacterial isolates were Staphylococcus epidermidis and Enterococcus faecalis, while Acinetobacter baumanii ranked third among all Intensive Care Unit (ICU) isolates. 7% of S. aureus had intermediate resistance to vancomycin. Although E. faecalis displayed no vancomycin resistance, 34% of vancomycin- resistant isolates were found among Enterococcus faecium, one of the highest rates found to date, emphasizing the difference between these two enterococcal species. All the Gram-positive pathogens were susceptible to linezolid, with the exception of approximately 2% of the enterococcal isolates that were intermediate with a minimum inhibitory concentration (MIC)=4 μg/ml. Almost 10% of Escherichia coli, 14% of Klebsiella pneumoniae, 22% of Serratia marcescens and 50% of Enterobacter cloacae were non-susceptible to cefotaxime. Amikacin was the most active antibiotic against P. aeruginosa that showed lack of susceptibility to ceftazidime, gentamicin, piperacillin and ciprofloxacin ranging from 20 to 35%. Finally, Acinetobacter baumanii showed a high level of resistance to all the antibiotics tested including imipenem (58%). The results obtained in this study, the first of its kind in Italy, offer indications for guiding empirical therapy and implementing specific interventions to fight antibiotic-resistant bacterial infections and their transmission in the hospital setting in Italy.     

Antibiotic resistance patterns of Gram-negative and Gram-positive strains isolated from inpatients with nosocomial infections in a tertiary hospital in Beijing,China from 2011 to 2014

This study was to evaluate the resistance of antimicrobial agents against pathogens from inpatients with nosocomial infection collected in Beijing, China, during 2011–2014. Measurement of minimum inhibitory concentrations (MICs) was carried out using the broth microdilution method with the Clinical and Laboratory Standards Institute (CLSI) guidelines as the indicator. A total of 5442 Gram-negative and 806 Gram-positive isolates were collected in this study in 2011–2014. Two carbapenem-resistant strains appeared among Escherichia coli (E. coli), while imipenem-resistant isolates increased in proportion from 0% to 8.2% among Klebsiella pneumonia (K. pneumonia) during 4 year. Acinetobacter baumannii (A. baumannii) revealed severe antibacterial resistance to most antimicrobial agents. In contrast, a decreasing trend on resistance had been observed among Pseudomonas aeruginosa (P. aeruginosa) especially after 2012, range from 1.8% for co-trimoxazole to 13.5% for piperacillin. The resistance of Staphylococcus aureus (S. aureus) also had the lowest resistant to linezolid and vancomycin (0.1%). In summary, antimicrobial-resistant nosocomial pathogens have gradually increased from 2011 to 2014, so improved surveillance of hospital-acquired infections and effective infection-control measures may be the best way to solve the present problem.     

In Vitro Efficacy of Levofloxacin Alone or in Combination Tested Against Multi-Resistant Pseudomonas aeruginosa Strains

Abstract

Levofloxacin, the S(-) isomer of ofloxacin, demonstrates In Vitro activity against Pseudomonas aeruginosa. To further characterize this activity, levofloxacin was tested against three populations of recent clinical isolates categorized by their resistance patterns to several other anti-pseudomonal agents. Results demonstrate the minimum inhibitory concentrations (MICs) for levofloxacin were generally two- to fourfold higher than for ciprofloxacin. Higher fluoroquinolone MICs were associated with MIC increases in other drugs. Levofloxacin demonstrated cross resistance against ciprofloxacin-resis-tant strains. Combinations of levofloxacin and several co-drugs revealed that the majority of evaluable interactions demonstrated indifferent action. Levofloxacin exhibited enhanced activity (additive or degrees of synergy) principally with piperacillin, aztreonam, or ceftazidime. The synergy and additive rate (21 to 30%) compared favorably with the enhanced interactions observed with gen-tamicin combined with piperacillin or ceftazidime (27 to 30%). Levofloxacin activity against P. aeruginosa was most comparable to that of ciprofloxacin, which was applicable against > 90% of strains found to be resistant to other classes of antimicrobial agents.     

Resistance patterns of Pseudomonas aeruginosa to carbapenems and piperacillin/tazobactam.

Pseudomonas aeruginosa is a major problem as a multiresistant nosocomial pathogen, especially in burns and other immunocompromised patients in our hospital. The present prospective study, conducted between June 1996 and December 1997, was aimed at determining the extent of its resistance against highly active antipseudomonal drugs, such as carbapenems (imipenem and meropenem) and ureidopenicillin with beta-lactamase inhibitor (piperacillin/tazobactam); existence of any cross resistance or difference in susceptibility between imipenem and meropenem; and to compare the activity of piperacillin/tazobactam with the two carbapenems against P. aeruginosa. Of the 357 P. aeruginosa isolates tested from 188 patients 37 (10.4%) were resistant to imipenem, 21 (5.9%) to meropenem and 50 (14%) to piperacillin/tazobactam. Cross resistance between the two carbapenems was observed in 5.9% of the isolates. Sixteen (43%) of the imipenem-resistant isolates were susceptible to meropenem but the reverse was observed in none. Amongst the 50 piperacillin/tazobactam-resistant isolates cross resistance with the two carbapenems was observed in 18 (36%) and in 9 (18%) only with imipenem; 23 (46%) were susceptible to both. Our results indicate that P. aeruginosa is least resistant to meropenem followed by imipenem and piperacillin/tazobactam. Cross resistance between the carbapenems and between carbapenems and piperacillin/tazobactam was found. The study further suggests that burns, cardiac-neuro-pediatric surgical, cancer and transplant patients are more susceptible to acquiring infection due to multiresistant P. aeruginosa than other types of patients and common infection sites were wounds, respiratory tract, urine, blood and intravascular lines.     

In Vitro Activity of Meropenem against Ciprofloxacin-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

Abstract

The in-vitro susceptibilities of a total of 174 ciprofloxacin-resistant Enterobacteriaceae and Pseudomonas aeruginosa were determined. According to the BSAC and NCCLS breakpoints, meropenem, aztreonam, ceftibuten, ceftazidime, imipenem and cefotaxime were the most active (>90%) antimicrobial agents tested against Enterobacteriaceae. Susceptibility of these strains to piperacillin/tazobactam, cefpodoxime and cefixime (84.96%) was higher than that to tobramycin, gentamicin and fosfomycin (50-75%). More than 90% of P. aeruginosa were susceptible to meropenem when both interpretative susceptibility breakpoint criteria were used. Piperacillin, piperacillin/tazobactam and ceftazidime were active against 50-75% of the same strains. Meropenem was the most active antimicrobial tested against all ciprofloxacin-resistant clinical isolates assayed.     

Prevalence of Type III Secretion Protein Exoenzymes and Antimicrobial Susceptibility Patterns from Bloodstream Isolates of Patients with Pseudomonas aeruginosa Bacteremia

Abstract

The purpose of this study was to determine the prevalence of two type III secretion effector proteins, exoU and exoS from bloodstream isolates of hospitalized patients with Pseudomonas aeruginosa (PSA) bacteremia, to characterize antimicrobial susceptibility patterns, and to compare mortality rates.

PSA bloodstream isolates and antibiotic susceptibility profiles were collected from a university-affiliated hospital. exoS and exoU genes were detected by polymerase chain reaction. Hospital mortality was assessed by medical chart review.

119 of 122 (97.5%) PSA bloodstream isolates contained either the exoS or exoU genes. exoS was the most prevalent (n=86; 70.5%) followed by exoU (n=31; 25.4%), both genes (n=2; 1.6%) or neither gene (n=3; 2.5%). Isolates containing the exoU gene were significantly more likely to be resistant to cefepime, ceftazidime, piperacillintazobactam, carbapenems, fluoroquinolones, and gentamicin (p<0.05 for all). Mortality was high in patients with PSA bacteremia and did not differ among patients infected with the exoS isolates (n=37; 43%) or exoU isolates (n=11; 35%).

One of two type III secretion effector proteins were almost universally present in PSA bloodstream isolates. Isolates containing the exoU gene were more likely to be resistant to multiple antibiotics.