Multicenter evaluation of the antimicrobial activity for six broad-spectrum beta-lactams in Venezuela: comparison of data from 1997 and 1998 using the Etest method. Venezuelan Antimicrobial Resistance Study Group

Ceftolozane/tazobactam: Literature review of its activity on Taiwanese isolates before its launch in Taiwan (2012-2021)

Ceftolozane, a novel cephalosporin, combined with tazobactam, a known β-lactamase inhibitor, shows robust antipseudomonal activity, although it doesn't cover carbapenemases. Our review of data from 2012 to 2021 in Taiwan highlights TOL/TAZ's in-vitro performance. TOL/TAZ is most effective against Pseudomonas aeruginosa (91.3-94.4 % susceptible, with an MIC <4 μg/mL). It also demonstrates good activity against Enterobacterales, including Escherichia coli (88-94.3 % susceptible), Klebsiella pneumoniae (72.6-84.1 % susceptible), Citrobacter koseri (93.3 % susceptible), Klebsiella oxytoca (98.1-100 % susceptible), and Proteus mirabilis (100 % susceptible). However, its efficacy varies among species typically associated with chromosomally-mediated AmpC production, such as Morganella morganii (100 % susceptible), Serratia marcescens (81.3-90.0 % susceptible), Enterobacter cloacae species complex (76.6-76.7 % susceptible), Klebsiella aerogenes (66.7-89.6% susceptible), and Citrobacter freundii (60.0 % susceptible). For carbapenem-nonsusceptible isolates, TOL/TAZ is less effective against K. pneumoniae and E. coli (susceptibility <10 %) but remains useful for P. aeruginosa (susceptibility 81.3-91.8 %). In conclusion, TOL/TAZ shows potent activity against P. aeruginosa and carbapenem-susceptible Enterobacterales in Taiwan.

Prevalence of Extended-Spectrum β-Lactamases in Multidrug-Resistant Klebsiella pneumoniae Isolates in Jordanian Hospitals

The increase in the prevalence of infections caused by certain bacteria, such as Klebsiella pneumonia (K. pneumoniae), is a global health concern. Bacterial production of an enzyme called extended-spectrum beta-lactamase (ESBL) can generate resistance to antimicrobial therapeutics. Therefore, between 2012 and 2013, we investigated K. pneumoniae that produce ESBLs with the prevalence of individual genes including blaSHV, blaCTX-M, blaTEM, and blaOXA isolated from clinical samples. A total of 99 variable diagnostic samples including blood from hematological malignancies (n = 14) or other clinical sources including sputum, pus, urine, and wound (n = 85) were analyzed. All samples' bacterial type was confirmed and their susceptibility to antimicrobial agents was established. Polymerase chain reaction (PCR) amplification was carried out to ascertain presence of specific genes that included blaSHV, blaCTX-M, blaTEM, and blaOXA. Plasmid DNA profiles were determined to assess significance between resistance to antimicrobial agents and plasmid number. It was found that among non-hematologic malignancy isolates, the highest rate of resistance was 87.9% to imipenem, with lowest rate being 2% to ampicillin. However, in hematologic malignancy isolates, the highest microbial resistance was 92.9% to ampicillin with the lowest rate of resistance at 28.6% to imipenem. Among collected isolates, 45% were ESBL-producers with 50% occurrence in hematologic malignancy individuals that were ESBL-producers. Within ESBL-producing isolates from hematologic malignancy individuals, blaSHV was detected in 100%, blaCTX-M in 85.7%, and blaTEM and blaOXA-1 at 57.1% and 27.1%, respectively. In addition, blaSHV, blaCTX-M, and blaOXA were found in all non-hematological malignancy individuals with blaTEM detected in 55.5% of samples. Our findings indicate that ESBLs expressing blaSHV and blaCTX-M genes are significantly prevalent in K. pneumoniae isolates from hematologic malignancy individuals. Plasmid analysis indicated plasmids in isolates collected from hematological malignancy individuals. Furthermore, there was a correlation between resistance to antimicrobial agents and plasmids within two groups analyzed. This study indicates an increase in incidence of K. pneumoniae infections displaying ESBL phenotypes in Jordan.

Antimicrobial Resistance and β-Lactamase Production in Clinically Significant Gram-Negative Bacteria Isolated from Hospital and Municipal Wastewater

Hospital and municipal wastewater contribute to the spread of antibiotic-resistant bacteria and genes in the environment. This study aimed to examine the antibiotic resistance and β-lactamase production in clinically significant Gram-negative bacteria isolated from hospital and municipal wastewater. The susceptibility of bacteria to antibiotics was tested using the disk diffusion method, and the presence of extended-spectrum β-lactamases (ESBL) and carbapenemases was determined using an enzyme inhibitor and standard multiplex PCR. Analysis of antimicrobial resistance of total bacterial strains (n = 23) revealed that most of them were resistant to cefotaxime (69.56%), imipenem (43.47%), meropenem (47.82%) and amoxicillin-clavulanate (43.47%), gentamicin (39.13%), cefepime and ciprofloxacin (34.78%), trimethoprim-sulfamethoxazole (30.43%). A total of 8 of 11 phenotypically confirmed isolates were found to have ESBL genes. The blaTEM gene was present in 2 of the isolates, while the blaSHV gene was found in 2 of the isolates. Furthermore, the blaCTX-M gene was found in 3 of the isolates. In one isolate, both the blaTEM and blaSHV genes were identified. Furthermore, of the 9 isolates that have been phenotypically confirmed to have carbapenemase, 3 were confirmed by PCR. Specifically, 2 isolates have the blaOXA-48 type gene and 1 have the blaNDM-1 gene. In conclusion, our investigation shows that there is a significant rate of bacteria that produce ESBL and carbapenemase, which can promote the spread of bacterial resistance. Identifying ESBL and carbapenemase production genes in wastewater samples and their resistance patterns can provide valuable data and guide the development of pathogen management strategies that could potentially help reduce the occurrence of multidrug resistance.

Prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae in Bahrain

OBJECTIVES

To determine the occurrence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in Bahrain.

METHODS

Retrospective analysis of records (January 2005-December 2006) at the Microbiology Laboratory of the Salmaniya Medical Complex, Bahrain which is the major national diagnostic laboratory.

RESULTS

Out of a total of 11,886 member of family of Enterobacteriaceae isolated, 2695 (22.6%) were ESBL producers. Majority of ESBL isolates were from inpatients (n=2363; 87.7%). Escherichia coli (52.2%) and Klebsiella pneumoniae (24.3%) were predominant and distributed comparatively in the hospital wards while Proteus spp. (17.6%) was predominant in medical wards. Urine was the major source (52.2%) with low occurrence in blood cultures. No carbapenem resistant isolates was identified but resistance to three classes of antibiotics was exhibited by >25% of the isolated ESBL strains. Nitrofurantoin resistance was identified in 38.2% of urinary isolates.

CONCLUSION

This is the first report from Bahrain and it indicates that the prevalence of ESBL-producing isolates is high. Carbapenems were the most active drug against the ESBL-producing isolates. We recommend strict infection control to prevent trafficking into the community.

Prevalence and molecular characterization of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in Riyadh, Saudi Arabia

BACKGROUND AND OBJECTIVES

Reports on extended-spectrum beta-lactamases (ESBL) production by Enterobacteriaceae, and especially in Klebsiella pneumoniae, are few in Saudi Arabia. Therefore, we determined the prevalence of ESBL in K pneumoniae from Riyadh and characterized the predominant beta-lactamase gene in these isolates.

METHODS

A total of 400 K pneumoniae samples were isolated from two hospitals in Riyadh during 2007 and screened for production of ESBL using ESBL-E-strips and combined disk methods. PCR assay was used to detect bla(TEM), bla(SHV), and bla(CTX-M) genes.

RESULTS

Phenotypic characterization identified a high ESBL rate of 55% of K pneumoniae isolates. ESBL producing K pneumoniae were PCR positive for SHV, TEM and CTX-M beta-lactamase genes with prevalences 97.3%, 84.1% and 34.1%, respectively. Within the CTX-M family, two groups of enzymes, CTX-M-1 and CTXM- 9-like genes were found with prevalences of 60% and 40%, respectively.

CONCLUSIONS

This study confirms the high rate of ESBL in K pneumoniae clinical isolates in hospitals in Riyadh. This study demonstrates the worldwide spread of bla(CTX-M) genes. This first report of the presence of the bla(CTX-M) gene in clincial isolates in Saudi Arabia is evidence of the continuing worldwide spread of this gene.

Prevalence of multiresistant gram-negative organisms in a tertiary hospital in Mwanza, Tanzania

Background

Antimicrobial resistance is fast becoming a global concern with rapid increases in multidrug-resistant Gram negative organisms. The prevalence of extended spectrum beta-lactamase (ESBL)-producing clinical isolates increases the burden on implementing infectious disease management in low socio-economic regions. As incidence can vary widely between regions, this study was done to determine resistance patterns of Gram-negative organisms at Bugando Medical Center, a tertiary hospital in Mwanza, Tanzania.

Methods

A total of 800 clinical samples (urine, wound swab, pus, blood, aspirate, sputum etc) were processed over a period of 6 months. Gram-negative bacteria were identified using conventional in-house biochemical tests and susceptibility to common antibiotics done using disc diffusion methods. The disc approximation method was used to identify ESBL producers.

Results

A total of 377 Gram-negative bacteria (GNB) recovered from 377 clinical specimens were analyzed of which 76.9% were Enterobacteriaceae. Among all GNB, 110/377 (29.2%) were found to be ESBL producers. Species specific ESBLs rate among Klebsiella pneumoniae, Escherichia coli, Acinetobacter spp, Proteus spp and other enterobacteria were 63.7%, 24.4%, 17.7%, 6.4% and 27.9% respectively. A statistically significant higher number of inpatients 100/283 (35.3%) compared to 10/94 (10.6%) of outpatients had ESBL-producing organisms (p = 0.000023). Rates of resistances to gentamicin, tetracycline, sulphamethaxazole/trimethoprim and ciprofloxacin were significantly higher among ESBLs isolates than non-ESBL isolates (p = 0.000001).

Conclusion

ESBL producing organisms are common at BMC (Bugando Medical Center) and pose a challenge to antibiotic therapy. Successful implementation of a routine detection of ESBL production is essential in designing appropriate antibiotic prescribing policies and infection control intervention programmes.

Prevalence and antimicrobial susceptibility pattern of extended-spectrum beta-lactamase-producing Enterobacteriaceae in the United Arab Emirates

OBJECTIVE

To investigate the prevalence and antibiotic susceptibility pattern of extended-spectrum beta-lactamases (ESBL)-producing Enterobacteriaceae among patients in the United Arab Emirates.

MATERIALS AND METHODS

A total of 130 Enterobacteriaceae comprising of Escherichia coli (n = 83), Klebsiella pneumoniae (n = 45) and Klebsiella oxytoca (n = 2) was studied. Of these 130 isolates, 64 were from urine. ESBL screening was by disc diffusion and confirmatory tests for ESBL phenotype were conducted using BD Phoenix ESBL System and cephalosporin/clavulanate combination discs. Susceptibility to a panel of antibiotics was evaluated.

RESULTS

Of the 130 isolates, 53 (41%) were identified as having ESBL phenotype; of these, 32 (60%) were E. coli, 20 (36%) K. pneumoniae and 2 (4%) K. oxytoca. ESBL phenotype was seen in 100% of endotracheal tubes isolates, 20 (31%) from urine, 7 (58%) from blood and 4 (80%) from catheter tips. Amikacin susceptibility was 100%. Over 90% of ESBL isolates showed resistance to aztreonam and cephalosporins. All Klebsiella isolates were carbapenem sensitive. One ESBL isolate showed intermediate resistance to imipenem and meropenem (both MIC 8 microg/ml), cefotetan (MIC 32 microg/ml) and piperacillin/tazobactam (MIC 32 microg/ml). MIC for the carbapenems was lower in non-ESBL isolates (0.034 microg/ml) than ESBL isolates (0.071 microg/ml). Resistance to gentamicin, ciprofloxacin and piperacillin/tazobactam was higher in ESBL than non-ESBL isolates (p < 0.05).

CONCLUSION

A high prevalence of ESBL-producing bacteria exists among in-patients in the United Arab Emirates. Amikacin and carbapenems remain the most effective drugs, but the presence of carbapenem-resistant ESBL-producing E. coli and occurrence of multidrug resistance are of concern. Continued surveillance and judicious antibiotic usage are recommended.

Extended-spectrum beta-lactamases: a clinical update

Extended-spectrum beta-lactamases (ESBLs) are a rapidly evolving group of beta-lactamases which share the ability to hydrolyze third-generation cephalosporins and aztreonam yet are inhibited by clavulanic acid. Typically, they derive from genes for TEM-1, TEM-2, or SHV-1 by mutations that alter the amino acid configuration around the active site of these beta-lactamases. This extends the spectrum of beta-lactam antibiotics susceptible to hydrolysis by these enzymes. An increasing number of ESBLs not of TEM or SHV lineage have recently been described. The presence of ESBLs carries tremendous clinical significance. The ESBLs are frequently plasmid encoded. Plasmids responsible for ESBL production frequently carry genes encoding resistance to other drug classes (for example, aminoglycosides). Therefore, antibiotic options in the treatment of ESBL-producing organisms are extremely limited. Carbapenems are the treatment of choice for serious infections due to ESBL-producing organisms, yet carbapenem-resistant isolates have recently been reported. ESBL-producing organisms may appear susceptible to some extended-spectrum cephalosporins. However, treatment with such antibiotics has been associated with high failure rates. There is substantial debate as to the optimal method to prevent this occurrence. It has been proposed that cephalosporin breakpoints for the Enterobacteriaceae should be altered so that the need for ESBL detection would be obviated. At present, however, organizations such as the Clinical and Laboratory Standards Institute (formerly the National Committee for Clinical Laboratory Standards) provide guidelines for the detection of ESBLs in klebsiellae and Escherichia coli. In common to all ESBL detection methods is the general principle that the activity of extended-spectrum cephalosporins against ESBL-producing organisms will be enhanced by the presence of clavulanic acid. ESBLs represent an impressive example of the ability of gram-negative bacteria to develop new antibiotic resistance mechanisms in the face of the introduction of new antimicrobial agents.

Management of serious nosocomial bacterial infections: do current therapeutic options meet the need?

Hospital-acquired bacterial infections pose a formidable challenge for healthcare providers, as patients often need to be treated empirically, at least initially, although delay of appropriate initial antimicrobial therapy is known to increase morbidity significantly and to increase mortality among affected patients. This elevated risk is compounded by the presence of antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum beta-lactamase-producing Enterobacteriaceae, Escherichia coli and Klebsiella pneumoniae. Prompt initiation of treatment with an appropriate antimicrobial agent that is active against both Gram-positive and Gram-negative organisms is prudent for patients with nosocomial infections. As the continued usefulness of vancomycin comes into question, the number of alternative agents that provide efficacy equal to that of vancomycin remains limited. The development of novel and effective alternative agents, such as tigecycline, is therefore important.

Typing of Acinetobacter baumannii isolated from hospital-acquired respiratory infections in a tertiary care centre in southern India

In an attempt to define the epidemiology of Acinetobacter baumannii infection, 27 isolates, obtained from hospital-acquired respiratory infections, were typed using random amplified polymorphic DNA (RAPD) profile and antimicrobial susceptibility patterns. Ten different patterns were obtained with ERIC2 primer: 14 isolates had a similar profile representing a single strain. Within RAPD types, isolates could be further classified based on their antibiogram; however, strains of different types had similar antibiograms. This study showed that many different genetic types of A. baumannii are prevalent in our hospital. While antibiograms alone are not sufficiently discriminatory, RAPD typing helps in identifying outbreaks and in assessing infection control procedures within a hospital.

Multicenter evaluation of antimicrobial resistance to six broad-spectrum beta-lactams in Colombia: comparison of data from 1997 and 1998 using the Etest method. The Colombian Antimicrobial Resistance Study Group

The minimum inhibitory concentrations of six broad-spectrum beta-lactam antimicrobial agents were determined in 1998 by use of the Etest versus a total of 823 bacteria in 11 Colombian hospital laboratories. These data were compared with results of a similar study conducted in 1997. The organisms tested included 532 recent clinical isolates of Enterobacteriaceae, 108 Pseudomonas aeruginosa, 94 Acinetobacter species, and 89 oxacillin-susceptible Staphylococcus aureus. Extended-spectrum beta-lactamase production was noted among 27.8 to 33.9% of Escherichia coli isolates and 41.7 to 46.7% of Klebsiella spp. isolates. Hyperproduction of Amp C cephalosporinases was observed with 10.5 to 31.4% of isolates of Enterobacter spp., Serratia spp., and Citrobacter spp. An increase in resistance to all of the beta-lactams was observed among Enterobacteriaceae, Acinetobacter spp. and P. aeruginosa when 1998 results were compared with those obtained in 1997. The overall rank order of activity of the six beta-lactams tested in 1998 versus all clinical isolates was imipenem (93.2% susceptible) > cefoperazone/sulbactam (84.1%) > cefepime (80.9%) > ceftazidime (70.7%) > aztreonam (65.7%) > cefotaxime (65.6%). In contrast, the rank order of these same agents tested against a similar collection of Colombian isolates in 1997 was imipenem (96.6% susceptible) > cefepime (93.6%) > cefoperazone/sulbactam (90.5%) > cefotaxime (74.9%) > aztreonam (74.3%) > ceftazidime (73.2%).