Lutfiye Mulazimoglu

Outcome of Cephalosporin Treatment for Serious Infections Due to Apparently Susceptible Organisms Producing Extended-Spectrum β-Lactamases: Implications for the Clinical Microbiology Laboratory

ABSTRACT Although extended-spectrum beta-lactamases (ESBLs) hydrolyze cephalosporin antibiotics, some ESBL-producing organisms are not resistant to all cephalosporins when tested in vitro. Some authors have suggested that screening klebsiellae or Escherichia colifor ESBL production is not clinically necessary, and when most recently surveyed the majority of American clinical microbiology laboratories did not make efforts to detect ESBLs. We performed a prospective, multinational study of Klebsiella pneumoniae bacteremia and identified 10 patients who were treated for ESBL-producingK. pneumoniae bacteremia with cephalosporins and whose infecting organisms were not resistant in vitro to the utilized cephalosporin. In addition, we reviewed 26 similar cases of severe infections which had previously been reported. Of these 36 patients, 4 had to be excluded from analysis. Of the remaining 32 patients, 100% (4 of 4) patients experienced clinical failure when MICs of the cephalosporin used for treatment were in the intermediate range and 54% (15 of 28) experienced failure when MICs of the cephalosporin used for treatment were in the susceptible range. Thus, it is clinically important to detect ESBL production by klebsiellae or E. coli even when cephalosporin MICs are in the susceptible range (≤ 8 μg/ml) and to report ESBL-producing organisms as resistant to aztreonam and all cephalosporins (with the exception of cephamycins).

International Prospective Study of Klebsiella pneumoniae Bacteremia: Implications of Extended-Spectrum β-Lactamase Production in Nosocomial Infections

Context Worldwide prevalence of extended-spectrum -lactamase (ESBL)producing organisms is of great concern because of their broad antibiotic resistance. Contribution Analysis of consecutive cases of Klebsiella pneumoniae bacteremia at 12 hospitals on 6 continents shows that although incidence varies widely among institutions, almost one third of cases of nosocomial bacteremia and almost one half of intensive care unitbased infections were caused by ESBL-producing organisms. Patient-to-patient spread is common, and prevention requires careful attention to routine infection control measures. Cautions Specific antibiotic exposures before K. pneumoniae infection cannot be confirmed as risk factors for ESBL-related infections on the basis of this study. The Editors Since the discovery that resistance of Staphylococcus aureus to penicillin is mediated by a -lactamase, much effort has been made to create -lactam antibiotics that are stable to common -lactamases. Cephalosporin antibiotics containing an oxyimino side-chain represent a major advance in antibiotic development. The merger of the oxyimino chain and a 2-amino-5-thiazolyl nucleus (in such antibiotics as ceftriaxone, cefotaxime, and ceftazidime) resulted in stability to the effects of the common TEM-1 and SHV-1 -lactamases produced by gram-negative bacilli, such as Escherichia coli and Klebsiella pneumoniae. However, within a few years of the commercial release of these antibiotics, gram-negative bacilli (especially K. pneumoniae) that harbored mutated versions of the parent TEM and SHV enzymes were detected. These and other newly detected -lactamases (for example, the functionally similar CTX-M types) hydrolyze -lactam antibiotics containing the oxyimino side-chain. Genes encoding these extended-spectrum -lactamases (ESBLs) were carried on transferable plasmids. These plasmids frequently carried determinants of resistance to other classes of antibiotics, particularly the aminoglycosides (1, 2). Thus, ESBL-producing gram-negative bacilli were found to truly be multiresistant pathogens: The majority of these strains were resistant to all -lactam antibiotics (with the exception of cephamycins and carbapenems), most aminoglycosides, trimethoprimsulfamethoxazole, and sometimes the fluoroquinolones. Although the prevalence of ESBL production among gram-negative bacilli varies geographically (and may even vary from hospital to hospital within a city), widespread recognition of the advent of these -lactamases has been lacking (3). Previous studies of the epidemiology of ESBL-producing organisms have been largely limited to single institutions (4, 5). Because substantial information on the epidemiology of ESBL-producing K. pneumoniae or other gram-negative bacilli is lacking, we established a collaboration of researchers from 7 countries on 6 continents to prospectively enroll consecutive patients with K. pneumoniae bacteremia. Methods Study Design We performed a prospective observational study of 440 consecutive, sequentially encountered patients with K. pneumoniae bacteremia at 12 hospitals in South Africa, Taiwan, Australia, Argentina, the United States, Belgium, and Turkey. No patient was excluded from analysis. Patients were enrolled from 1 January 1996 to 31 December 1997. Patients were older than 16 years of age and had positive blood cultures for K. pneumoniae. The investigators completed a 188-item study form on each episode of K. pneumoniae bacteremia. Patients were followed for 1 month after the onset of bacteremia to assess clinical outcome, including death and infectious complications. The study was observational in that administration of antimicrobial agents and other therapeutic management was controlled by the patients physician rather than the investigators (6). The study was approved by institutional review boards as required by local hospital policy at the time of the study. Definitions All study definitions were established before data analysis. Nosocomial bacteremia was defined as K. pneumoniae bacteremia occurring more than 48 hours after admission to hospital. An episode of bacteremia was defined as the period of 14 days from the time of collection of the first blood culture positive for K. pneumoniae. Severity of acute illness was assessed at the time of the positive blood cultures by using the Pitt bacteremia score, a previously validated scoring system that is based on mental status, vital signs, requirement for mechanical ventilation, and recent cardiac arrest (Table 1) (7, 8). Severity of illness in patients in an intensive care unit at the time of onset of bacteremia was assessed by using the Acute Physiology and Chronic Health Evaluation-3 score (9). Site of infection was determined to be pneumonia, urinary tract infection, meningitis, incisional wound infection, other soft-tissue infection, intra-abdominal infection, or primary bloodstream infection according to Centers for Disease Control and Prevention definitions (10). Previous antibiotic therapy was defined as antibiotics given for at least 2 days within the 14 days before an episode of K. pneumoniae bacteremia (11). Antibiotic therapy for the episode of K. pneumoniae bacteremia was the receipt of antibiotics that are active in vitro against the blood culture isolate (that is, susceptible according to 1999 NCCLS breakpoints [12], given for at least 2 days within the first 5 days of collection of the first positive blood culture. Mortality was death from any cause within 14 days from the date of the first positive blood culture for K. pneumoniae. Table 1. The Pitt Bacteremia Score* Microbiological Analysis Production of ESBL was phenotypically determined by broth dilution using the NCCLS performance standards current as of January 1999 (12). A 3 twofold decrease in the minimal inhibitory concentration (MIC) for cefotaxime or ceftazidime tested in combination with clavulanic acid compared with its MIC when tested alone was considered phenotypic confirmation of ESBL production. For example, an isolate with a ceftazidime MIC of 8 g/mL and a ceftazidimeclavulanic acid MIC of 1 g/mL fulfills this definition of an ESBL-producing organism (12). The MICs of antibiotics commonly used in the treatment of gram-negative sepsis were determined for the ESBL-producing isolates by using the gradient diffusion method (Etest, AB Biodisk, Solna, Sweden). Pulsed-field gel electrophoresis was used to establish the genotypic relationships of ESBL-producing isolates from each hospital (11). Statistical Analysis All statistical comparisons were made by using PROPHET Statistics software, version 6.0 (ABTech-BBN Corp., Charlottesville, Virginia) or Stata software, version 7.0 (Stata Corp., College Station, Texas). For bivariate comparisons, the chi-square or Fisher exact test was used to compare categorical variables. Continuous variables were compared by using the t-test or the MannWhitney test. Length of stay before positive blood culture was missing for 10 (4%) patients, all of whom had been readmitted within 1 week of discharge. Length of stay for these 10 patients was therefore estimated by using a predictive model that assumed missing at random. Because previous receipt of antibiotics was not random, a propensity score model was used to further evaluate the effect of receipt of antibiotics containing an oxyimino group as a risk for ESBL production. The score was calculated by using a logistic model in which receipt of -lactam antibiotics containing an oxyimino group (cefuroxime, ceftriaxone, cefotaxime, ceftazidime, or aztreonam) was the dependent variable (scored as yes or no) and predictors were all available factors hypothesized to influence the receipt of antibiotic therapy (underlying patient conditions), with adjustment for center by using the indicator variables for site. Factors included in the calculation of this score were age, sex, admission from nursing home, underlying diseases (cancer, HIV infection, diabetes, or renal and liver disease), previous surgery, use of corticosteroids, presence of a central line, mechanical ventilatory support, presence of a nasogastric tube, and the indicator variables for site. A logistic model clustered on the patient that used receipt of antibiotics containing an oxyimino group and the quintile stratified score was then used to evaluate the risk for ESBL production. Role of the Funding Source Merck and Company provided support for laboratory studies but played no role in study design, conduct of the study, interpretation of the results, or approval of the study before publication. Results During the study period, 455 episodes of K. pneumoniae bacteremia occurred in 440 patients; of these, 202 (44.4%) episodes in 196 patients were community acquired and 253 (55.6%) episodes in 244 patients were nosocomially acquired. Table 2 shows the characteristics of the participants. Table 2. Characteristics of 244 Patients with Nosocomial Klebsiella pneumoniae Bacteremia Of the episodes of K. pneumoniae bacteremia, 18.7% (85 of 455) were due to ESBL-producing organisms and 81.1% (369 of 455) were due to nonESBL-producing organisms. One additional episode involved an isolate that showed a markedly elevated MIC for the oxyimino -lactam antibiotics but no decrease in MIC with the addition of clavulanic acid. This isolate had an MIC for cephamycin antibiotics in the resistant range and may have possessed an AmpC-like enzyme. This episode was excluded from further analysis. Seventy-eight of 253 (30.8%) episodes of nosocomial bacteremia were due to ESBL-producing organisms. Table 3 shows the sites of infection associated with nosocomial ESBL-producing K. pneumoniae bacteremia. Fewer episodes of community-acquired K. pneumoniae bacteremia (3.5% [7 of 202]) were due to ESBL-producing organisms (P <0.001) (risk ratio, 8.9 [95% CI, 4.2 to 18.8]). Of the 253 episodes of nosocomial bacteremia, 69 were acquired in the intensive care unit. Of these 69 episodes, 30 (43.5%) episodes o

Antibiotic Therapy for Klebsiella pneumoniae Bacteremia: Implications of Production of Extended-Spectrum β-Lactamases

The prevalence of extended-spectrum beta -lactamase (ESBL) production by Klebsiella pneumonia approaches 50% in some countries, with particularly high rates in eastern Europe and Latin America. No randomized trials have ever been performed on treatment of bacteremia due to ESBL-producing organisms; existing data comes only from retrospective, single-institution studies. In a prospective study of 455 consecutive episodes of Klebsiella pneumoniae bacteremia in 12 hospitals in 7 countries, 85 episodes were due to an ESBL-producing organism. Failure to use an antibiotic active against ESBL-producing K. pneumoniae was associated with extremely high mortality. Use of a carbapenem (primarily imipenem) was associated with a significantly lower 14-day mortality than was use of other antibiotics active in vitro. Multivariate analysis including other predictors of mortality showed that use of a carbapenem during the 5-day period after onset of bacteremia due to an ESBL-producing organism was independently associated with lower mortality. Antibiotic choice is particularly important in seriously ill patients with infections due to ESBL-producing K. pneumoniae.

Epidemiology of Ciprofloxacin Resistance and Its Relationship to Extended-Spectrum β-Lactamase Production in Klebsiella pneumoniae Isolates Causing Bacteremia

A prospective study of Klebsiella pneumoniae bacteremia was performed in 12 hospitals in 7 countries. Of 452 episodes of bacteremia, 25 (5.5%) were caused by K. pneumoniae that was resistant in vitro to ciprofloxacin. Extended-spectrum beta-lactamase (ESBL) production was detected in 15 (60%) of 25 ciprofloxacin-resistant isolates, compared with 68 (16%) of 427 ciprofloxacin-susceptible strains (P=.0001). Multivariate analysis revealed that risk factors for ciprofloxacin resistance in K. pneumoniae included prior receipt of a quinolone (P=.0065) and an ESBL-producing strain (P=.012). In all, 18% of ESBL-producing isolates were also ciprofloxacin-resistant. Pulsed-field gel electrophoresis showed that 11 of the 15 ciprofloxacin-resistant ESBL-producing strains belonged to just 4 genotypes, suggesting that patient-to-patient transmission of such strains occurred. The close relationship between ESBL production and ciprofloxacin resistance is particularly worrisome because the first reported instance of plasmid-mediated ciprofloxacin resistance has been in an isolate of K. pneumoniae also possessing an ESBL.

Community-Acquired Klebsiella pneumoniae Bacteremia: Global Differences in Clinical Patterns

We initiated a worldwide collaborative study, including 455 episodes of bacteremia, to elucidate the clinical patterns of Klebsiella pneumoniae. Historically, community-acquired pneumonia has been consistently associated with K. pneumoniae. Only four cases of community-acquired bacteremic K. pneumoniae pneumonia were seen in the 2-year study period in the United States, Argentina, Europe, or Australia; none were in alcoholics. In contrast, 53 cases of bacteremic K. pneumoniae pneumonia were observed in South Africa and Taiwan, where an association with alcoholism persisted (p=0.007). Twenty-five cases of a distinctive syndrome consisting of K. pneumoniae bacteremia in conjunction with community-acquired liver abscess, meningitis, or endophthalmitis were observed. A distinctive form of K. pneumoniae infection, often causing liver abscess, was identified, almost exclusively in Taiwan.

Preparation and Characterisation of Natamycin: γ-Cyclodextrin Inclusion Complex and its Evaluation in Vaginal Mucoadhesive Formulations

Novel formulations of vaginal bioadhesive tablets were prepared where the natamycin was complexed with gamma-cyclodextrin (NT-gamma CyD) to increase the solubility and stability of NT in aqueous solutions and reduce the side effects of the drug without decreasing antimycotic activity. Favourable interactions between the NT and gamma CyD and formation of the 1:1 inclusion complex were observed. The MIC(90) of both NT alone and NT-gamma CyD complexes were below 0.0313 microg mL(-1), suggesting that complexation with gamma CyD has effectively increased the antimycotic activity of NT, thus indicating the clinical usefulness of NT-gamma CyD complexes. The sustained drug release of NT was achieved to over 8 h periods by altering the polymer component of formulations which was responsible for differences in water absorption and erosion behaviour of the tablets. Bioadhesion studies have clearly indicated that enhancement of mucoadhesion was achieved by inclusion of Carbopol 934P and by tailoring the ratio of Carbopol 934P in the formulation, a high mucoadhesion to vaginal mucosa can be achieved. Hence, the formation of complex between NT and gamma CyD and effective combination with polymers attain a bioadhesive and sustained release formulation of NT suitable for vaginal delivery and the effective treatment of Candida infections.

The preparation of ciprofloxacin hydrochloride-loaded chitosan and pectin microspheres: THEIR EVALUATION IN AN ANIMAL OSTEOMYELITIS MODEL

Ciprofloxacin hydrochloride-loaded microspheres were prepared by a spray-drying method using pectin and chitosan. The effects of different polymers and drug ratios were investigated. The most appropriate carriers were selected by in vitro testing. A rat methicillin-resistant Staphylococcus aureus osteomyelitis model was used to evaluate the effects of the loaded microspheres. The drug was released rapidly from the pectin carrier but this was more sustained in the chitosan formulation.Chitosan microspheres loaded with ciprofloxacin hydrochloride were more effective for the treatment of osteomyelitis than equivalent intramuscular antibiotics.

Bioadhesive tablets containing cyclodextrin complex of itraconazole for the treatment of vaginal candidiasis.

Itraconazole (ITR) is commonly used in the treatment of Candida infections. It has a nephrotoxic effect and low bioavailability in patients who suffer from renal insufficiency, and its poor solubility in water makes ITR largely unavailable. Cyclodextrins (CyDs) are used to form inclusion complexes with drugs to improve their aqueous solubility and to reduce their side effects. In this study, ITR was complexed with γ-cyclodextrin (γ-CyD), hydroxypropyl-β-cyclodextrin (HP-β-CyD), methyl-β-cyclodextrin (Met-β-CyD) and sulphobutyl ether-β-cyclodextrin (SBE7-β-CyD) to increase its water solubility and to reduce the side effects of the drug without decreasing antifungal activity. Complex formation between ITR and CyDs was evaluated using SEM, (1)H NMR and XRD studies. The antifungal activity of the complexes was analyzed on Candida albicans strains, and the susceptibility of the strains was found to be higher for the ITR-SBE7-β-CyD complex than for the complexes that were prepared with other CyDs. Vaginal bioadhesive sustained release tablet formulations were developed using the ITR-SBE7-β-CyD inclusion complex to increase the residence time of ITR in the vagina, thereby boosting the efficacy of the treatment. The swelling, matrix erosion and bioadhesion properties of formulations and the drug release rate of these tablets were analyzed, and the most therapeutically effective vaginal formulation was determined.

Antibiotics are not needed during tube thoracostomy for spontaneous pneumothorax: an observational case study

BackgroundUsefulness of prophylactic antibiotics following tube thoracostomy remains controversial in the literature. In this study, we aimed to investigate the consequences of closed tube thoracostomy for primary spontaneous pneumothorax without the use of antibiotics.MethodsOne-hundred and nineteen patients underwent tube thoracostomy for primary spontaneous pneumothorax. None of them received prophylactic antibiotic treatment. Eight patients with prolonged air leak undergoing either video assisted thoracoscopic surgery or thoracotomy were excluded.ResultsOf the remaining 111 (104 male and 7 female), 28 (25%) patients developed some induration around the entry site of chest tube that settled without further treatment. White blood cell count was high without any other evidence of infection in 12 (11%) patients and returned to its normal levels before discharge home in all. There was also some degree of fever not lasting for more than 48 hours in 8 (7%) patients. Bacterial cultures from suspected sites did not reveal any significant growth in these patients.ConclusionProphylactic antibiotic treatment seems avoidable during closed tube thoracostomy for primary spontaneous pneumothorax. This policy was not only cost-effective but also prevented our patients from detrimental properties of unnecessary antibiotic use, such as development of drug resistance and undesirable side effects.

Sodium fusidate-poly(D,L-lactide-co-glycolide) microspheres: Preparation, characterisation and in vivo evaluation of their effectiveness in the treatment of chronic osteomyelitis

Purpose: The aim of this study was to prepare poly(D,L-lactide-co-glycolide) (PLGA) microspheres containing sodium fusidate (SF) using a double emulsion solvent evaporation method with varying polymer:drug ratios (1:1, 2.5:1, 5:1) and to evaluate its efficiency for the local treatment of chronic osteomyelitis. Methods: The particle size and distribution, morphological characteristics, thermal behaviour, drug content, encapsulation efficiency and in vitro release assessments of the formulations had been carried out. Sterilized SF-PLGA microspheres were implanted in the proximal tibia of rats with methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. After 3 weeks of treatment, bone samples were analysed with a microbiological assay. Results: PLGA microspheres between the size ranges of 2.16–4.12 µm were obtained. Production yield of all formulations was found to be higher than 79% and encapsulation efficiencies of 19.8–34.3% were obtained. DSC thermogram showed that the SF was in an amorphous state in the microspheres and the glass transition temperature (Tg) of PLGA was not influenced by the preparation procedure. In vitro drug release studies had indicated that these microspheres had significant burst release and their drug release rates were decreased upon increasing the polymer:drug ratio (p < 0.05). Based on the in vivo data, rats implanted with SF-PLGA microspheres and empty microspheres showed 1987 ± 1196 and 55526 ± 49086 colony forming unit of MRSA in 1 g bone samples (CFU/g), respectively (p < 0.01). Conclusion: The in vitro and in vivo studies had shown that the implanted SF loaded microspheres were found to be effective for the treatment of chronic osteomyelitis in an animal experimental model. Hence, these microspheres may be potentially useful in the clinical setting.