Urinary tract infections (UTIs) are the most frequent hospital infections and among the most commonly observed community acquired infections. Alongside their clinical importance, they are notorious ...because the pathogens that cause them are prone to acquiring various resistance determinants, including extended-spectrum beta-lactamases (ESBL); plasmid-encoded AmpC β-lactamases (p-AmpC); carbapenemases belonging to class A, B, and D;
genes encoding reduced susceptibility to fluoroquinolones; as well as genes encoding enzymes that hydrolyse aminoglycosides. In
and
, the dominant resistance mechanisms are ESBLs belonging to the CTX-M, TEM, and SHV families; p-AmpC; and (more recently) carbapenemases belonging to classes A, B, and D. Urinary
isolates harbour metallo-beta-lactamases (MBLs) and ESBLs belonging to PER and GES families, while carbapenemases of class D are found in urinary
isolates. The identification of resistance mechanisms in routine diagnostic practice is primarily based on phenotypic tests for the detection of beta-lactamases, such as the double-disk synergy test or Hodge test, while polymerase chain reaction (PCR) for the detection of resistance genes is mostly pursued in reference laboratories for research purposes. As the emergence of drug-resistant bacterial strains poses serious challenges in the management of UTIs, this review aimed to appraise mechanisms of resistance in relevant Gram-negative urinary pathogens, to provide a detailed map of resistance determinants in Croatia and the world, and to discuss the implications of these resistance traits on diagnostic approaches. We summarized a sundry of different resistance mechanisms among urinary isolates and showed how their prevalence highly depends on the local epidemiological context, highlighting the need for tailored interventions in the field of antimicrobial stewardship.
The susceptibility of 66 clinical and environmental B. cereus isolates were tested to selected antimicrobials by a broth microdilution method. All strains were resistant to β-lactams and susceptible ...to gentamicin and imipenem. Sixty-five (98.5%) isolates were susceptible to meropenem and ciprofloxacin and 74.2% to azithromycin. Significant differences in MIC values between environmental and clinical isolates were not demonstrated (p > 0.05). According to the disc diffusion method, 80.3%–98.5% of the strains were resistant to one or more of four cephalosporins. The presence of genes for B. cereus β-lactamases BCI, BCII, BCIII, extended-spectrum β-lactamases from the CTX and TEM family and the carbapenemases belonging to IMP and VIM family was studied. BlaII genes were expressed in all isolates; the PCR products for blaIII were also detected in two strains, but none of them was positive for blaI. The amplicon of the family blaCTX-M, mostly M-1 and M-15, was confirmed among 68.2% of the isolates, while were blaVIM-like genes determined in 21.2% of the samples.
•The susceptibility of clinical and environmental B. cereus isolates was tested.•Apart from metallo-β-lactamases, B. cereus can form different types of ESBLs.•The ESBLs from the CTX and TEM family were confirmed in 68% of B. cereus strains.•Carbapenemases belonging to VIM family were determined in 21% of the samples.•B. cereus could be a precursor of transmittable MBLs to other pathogenic species.
Recently, emergence of carbapenem-resistance, in particular due to
Klebsiella pneumoniae
carbapenemase (KPC), was observed among
K
.
pneumoniae
causing urinary tract infections in Croatia. The aim of ...the study was to characterize, antimicrobial susceptibility, carbapenem resistance, virulence traits and plasmid types of the urinary KPC positive isolates of
K. pneumoniae
. The antimicrobial susceptibility to a wide range of antibiotics was determined by broth microdilution method. The transferability of meropenem resistance was determined by conjugation (broth mating method) employing
Escherichia coli
J63 strain resistant to sodium azide. Genes encoding broad and extended-spectrum β-lactamases, plasmid-mediated AmpC β-lactamases, group A and B carbapenemases, and carbapenem hydrolyzing oxacillinases (bla
OXA-48like
), respectively, were determined by Polymerase chain reaction (PCR). In total 30 KPC-positive
K
.
pneumoniae
urinary isolates collected from different regions of Croatia were analysed. The isolates were uniformly resistant to all tested antibiotics except for variable susceptibility to gentamicin, sulphamethoxazole/trimethoprim, and colistin, respectively. Four isolates were resistant to colistin with MICs values ranging from 4 to 16 mg/L. All tested isolates were susceptible to ceftazidime/avibactam. Sixteen isolates transferred meropenem resistance to
E. coli
recipient strain by conjugation. Other resistance markers were not co-transferred. PCR was positive for bla
KPC
and bla
SHV
genes in all isolates whereas 13 isolates tested positive also for bla
TEM
genes. PCR based replicon typing (PBRT) revealed the presence of FIIs in 13 and FIA plasmid in two strains. The study showed dissemination of KPC-producing
K. pneumoniae
in urinary isolates, posing a new epidemiological and treatment challenge. Sulphamethoxazole/trimethoprim, colistin, and ceftazidime/avibactam remain so far, as the therapeutic options.
In the previous studies OXA-23-like and OXA-24-like β-lactamase were reported among
Acinetobacter baumannii
in both hospitals and long-term care facilities (LTCF) in Croatia. The aim of this study ...was to analyze clinical and sewage
A. baumannii
isolates from two nursing homes in Zagreb, with regard to antibiotic susceptibility and resistance mechanisms, to determine the route of spread of carbapenem-resistant isolates. Nine clinical isolates were collected from February to May 2017 whereas in April 2017, ten
A. baumannii
isolates were collected from sewage of two nursing homes in Zagreb. Antibiotics susceptibility was determined by broth microdilution method. The presence of carbapenemase and extended spectrum β-lactamases (ESBL) encoding genes was explored by PCR. Conjugation and transformation experiments were performed as previously described. Genotyping was performed by SG determination, PFGE and MLST. Seven clinical isolates were positive for
bla
OXA24-like
whereas two clinical and environmental carbapenem-resistant isolates, respectively, were found to possess
bla
OXA-23-like
genes. Attempts to transfer imipenem resistance were unsuccessful indicating chromosomal location of
bla
OXA-23
gene. All carbapenem-resistant isolates belonged to SG- 1 (IC-2) whereas the rest of the isolates susceptible to carbapenems were allocated to SG- 2 (IC-1). PFGE analysis revealed low degree of genetic variability within both IC- I and IC- II. MLST corroborated that two environmental OXA-23 isolates belong to the ST-195. This study showed dissemination of OXA-23 producing
A. baumannii
from the nursing home into the urban sewage. Disinfection of nursing home sewage should be recommended in order to prevent the spread of resistance genes into the community sewage.
Pseudomonas aeruginosa is a leading cause of nosocomial infections. Given the constant rise in resistance, adequate therapy is increasingly demanding. Fosfomycin recently became an appealing ...treatment option of bacterial infections due to multidrug-resistant bacteria (MDR). So far, fosfomycin synergy with other antibiotics has been assessed in studies, but only a limited number focused on MDR P. aeruginosa and on the effect of these combinations on the duration of the postantibiotic effect (PAE). We investigated synergy of fosfomycin with an array of antipseudomonal antibiotics using gradient diffusion strip cross method and time-kill method, and their effect on the duration of PAE against 51 variously resistant P. aeruginosa isolates. The highest rate of synergy was observed for combination with ceftazidime (23.4%) and gentamicin (19.1%). The PAE of antibiotic combinations was superior to that of the drugs alone. Our findings indicate that fosfomycin combination therapy may be a valuable treatment alternative.
In recent years, a dramatic increase in the prevalence of
Escherichia coli
strains producing extended-spectrum β-lactamases (ESBLs) has been observed — both in the community and in healthcare ...settings. This multicentric study aimed to characterize ESBLs produced by
E. coli
isolates causing hospital-onset and community urinary tract infections, as well as to compare their antimicrobial sensitivity patterns, β-lactamase content and plasmid types. Phenotypic tests for the detection of ESBLs and plasmid-mediated AmpC β-lactamases were initially pursued, followed by molecular detection of resistance genes, plasmid characterization, genotyping with pulsed-field gel electrophoresis and whole genome sequencing (WGS). The isolates exhibited high level of resistance to expanded-spectrum cephalosporins (ESC) and carried CTX-M (cefotaximase-Munich) or TEM (Temoniera) β-lactamases. All six representative isolates subjected to WGS belonged to the widespread clone ST131. In conclusion, our study demonstrated dissemination of group 1 CTX-M positive
E. coli
in different geographic regions of Croatia, but also different components of the health care systems (hospitals, nursing homes and the community) and confirmed the switch from SHV-2 (suphydril variant) and SHV-5 ESBLs to the nation-wide predominance of group 1 CTX-M β-lactamases. Different plasmids were shown to be associated with the dissemination of
bla
CTX-M
genes in different geographic regions of Croatia.
Abstract
Fast microbiological diagnostics (MDx) are needed to ensure early targeted antimicrobial treatment in sepsis. This systematic review focuses on the impact on antimicrobial management and ...patient outcomes of MDx for pathogen and resistance gene identification compared with blood cultures. PubMed was searched for clinical studies using either whole blood directly or after short-term incubation. Twenty-five articles were retrieved describing the outcomes of 8 different MDx. Three interventional studies showed a significant increase in appropriateness of antimicrobial therapy and a nonsignificant change in time to appropriate therapy. Impact on mortality was conflicting. Length of stay was significantly lower in 2 studies. A significant decrease in antimicrobial cost was demonstrated in 6 studies. The limitations of this systematic review include the low number and observed heterogeneity of clinical studies. In conclusion, potential benefits of MDx regarding antimicrobial management and some patient outcomes were reported. More rigorous intervention studies are needed focusing on the direct benefits for patients.
Extended-spectrum β-lactamases (ESBLs) hydrolyse extended-spectrum cephalosporins (ESC) and aztreonam. As ESBL-producing organisms have been identified in food producing animals, the aim of our study ...was to detect and analyse such
isolates from poultry. Antibiotic susceptibility of the isolates was determined with disk-diffusion and broth microdilution methods. ESBLs were detected with the double-disk synergy and inhibitor-based test with clavulanic acid. The transferability of cefotaxime resistance was determined with conjugation experiments, and genes encoding ESBLs, plasmid-mediated AmpC β-lactamases, and quinolone resistance determinants identified by polymerase chain reaction. The study included 108 faecal samples (cloacal swabs) from 25 different poultry farms in the Zenica-Doboj Canton, Bosnia and Herzegovina. Of these, 75 (69.4 %) were positive for
, of which 27 were resistant to cefotaxime, amoxicillin, cefazoline, and cefriaxone, and susceptible to imipenem, meropenem, ertapenem, and amikacin. All 27 cefotaxime-resistant isolates were positive in double-disk synergy and combined disk tests. Eighteen isolates transferred cefotaxime resistance to
recipient. Twenty-one isolates were positive for the
cluster genes and seven for
. Fourteen were positive for the
genes. The most frequent plasmid incompatibility group was IncFIB, whereas IncFIA and Inc HI1 were present in only a few isolates. Two different sequence types (STs) were identified: ST117 and ST155. The emergence of ESBL-producing
in farm animals presents a public health threat, as they can colonise the intestine and cause infections in humans.
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