Extended-spectrum β-lactamase/AmpC-producing uropathogenic Escherichia coli from HIV patients: do they have a low virulence score?

Low temperatures do not impair the bacterial plasmid conjugation on poultry meat

Conjugation plays an important role in the dissemination of antimicrobial resistance genes. Besides, this process is influenced by many biotic and abiotic factors, especially temperature. This study aimed to investigate the effect of different conditions of temperature and storage (time and recipient) of poultry meat, intended for the final consumer, affect the plasmid transfer between pathogenic (harboring the IncB/O-plasmid) and non-pathogenic Escherichia coli organisms. The determination of minimal inhibitory concentrations (MIC) of ampicillin, cephalexin, cefotaxime, and ceftazidime was performed before and after the conjugation assay. It was possible to recover transconjugants in the poultry meat at all the treatments, also these bacteria showed a significant increase of the MIC for all antimicrobials tested. Our results show that a non-pathogenic E. coli can acquire an IncB/O-plasmid through a conjugation process in poultry meat, even stored at low temperatures. Once acquired, the resistance genes endanger public health especially when it is about critically and highly important antimicrobials to human medicine.

Clonal groups of extended-spectrum β-lactamase and biofilm producing uropathogenic Escherichia coli in Iran

Pathogenicity of a bacterium is affected by the social characteristics of the population and environmental factors. The ability of biofilm formation among β-lactamase-producing uropathogenic Escherichia coli (UPEC) could facilitate the exchange of antibiotic-resistance genes, which resulted in widespread dissemination of antibacterial drug resistance. We investigated the prevalence of biofilm and β-lactamase producing UPECs among patients with urinary tract infection (UTI) in two cities with different demographics and climates in Iran. A total of 265 E. coli was isolated from patients with UTIs from two referral hospitals (n = 191) and two outpatient clinics (n = 74) in Isfahan and Zahedan, Iran. Production of curli and cellulose, and, biofilm formation was investigated using Congo red agar and microtiter plate methods, respectively. Biofilm producing (BFP) isolates (n = 107) were further characterized using rep-PCR, antimicrobial susceptibility testing and extended-spectrum β-lactamase (ESBL)/AmpC phenotypic production. Isolates were also screened for the presence of carbapenemase, ESBL and AmpC genes using multiplex PCR.   High diversity was found among BFP strains in both cities, with 58% strains producing ESBL and 21% producing AmpC. ESBL (98%), AmpC (50%) and carbapenemase genes (40%) were identified in BFP strains with ESBL-positive phenotype, respectively. The prevalence of BFP strains, antibiotic resistance and β-lactamase genes in Zahedan, a low socioeconomic city with a warm climate, was significantly higher than that of Isfahan. High prevalence of biofilm and β-lactamase producing UPEC strains among strains from Zahedan suggests that socioeconomic status and environmental factors might have a role in pathogenicity of the strains.

Occurrence of extended-spectrum β-lactamase, AmpC, and carbapenemase-producing genes in gram-negative bacterial isolates from human immunodeficiency virus infected patients

BACKGROUND

Progressive decline of immune response in HIV patients makes them susceptible to frequent bacterial infections. High usage of antibiotics influences the emergence of multidrug-resistant bacteria and worsens the clinical outcomes. In this study, the occurrence of drug-resistant genes in Gram-negative bacterial isolates from HIV patients in South India was analyzed.

METHODS

A total of 173 Gram-negative bacterial (GNB) isolates from HIV patients were screened for antibiotic susceptibility profile using the Kirby-Bauer diskdiffusion method. Positivity of drug-resistant genes was analyzed using polymerase chain reaction method.

RESULTS

In this study, 72.8% of bacterial isolates were obtained from urine specimens, and Escherichia coli (47.4%) was the predominantly isolated bacterium. Overall, 87.3% and 83.2% of GNB were resistant to 3rd generation cephalosporin antibiotics such as cefotaxime and ceftazidime, respectively, 56.6% were resistant to cephamycin (cefoxitin) and 43% to carbapenem (imipenem) antibiotics. Extended-spectrum β-lactamases (ESBL) production was noted among 79.5% of GNB isolates, followed by AmpC (57.1%) and Metallo β-lactamases (37.3%). Molecular analysis revealed that ESBL genes such as blaTEM (94.1%), blaCTX-M (89.2%), and blaSHV (24.2%) were detected at higher levels among GNB isolates. Carbapenemase-producing genes such as blaOXA-48 (20%), blaOXA-23 (2.6%), and both blaOXA-23 and blaOXA-51 like genes (2.6%) and AmpC producing genes such as blaCIT (26.7%), blaDHA (3.6%), and blaACC (1.8%) were detected at low-level.

CONCLUSIONS

This study concludes that ESBL producing genes are detected at high level among gram-negative bacterial isolates from HIV patients in South India.

Phenotypic and Molecular Characterization of β-Lactamases among Enterobacterial Uropathogens in Southeastern Nigeria

Little is known about the molecular basis of antibiotic resistance among uropathogens in Southeast Nigeria. The aim of the study was to characterize enterobacterial uropathogens with respect to drug resistance. One hundred (100) enterobacterial uropathogens were studied. Their antibiotic susceptibility patterns were evaluated using disk diffusion, screened, and confirmed phenotypically for the presence of β-lactamases: ESBL, AmpC, carbapenemase, and MBLs. Screen positives were further tested for various β-lactamase genes by PCR. Our isolates showed variable resistance to most drugs tested. Out of the 58 ESBL screen positive E. coli, 35 were confirmed positive with PCR. The predominant ESBL gene was bla_TEM while bla_SPM was the most prevalent among MBL genes. Forty-six percentage of the screen positive Salmonella isolates coharbored bla_{TEM + SHV} genes. Nine of the 10 ESBL screen positive K. pneumoniae were phenotypically and PCR positive. Three isolates of K. pneumoniae were positive for MBL genes. All the 10 C. freundii were positive for ESBL genes. The study showed high prevalence of drug-resistant genes among the enterobacterial uropathogens. Majority of the uropathogens harbored >1 antibiotic-resistant gene, and the most predominant gene was ESBL (bla_TEM) followed by the MBL (SPM) gene.

Low rate of gut colonization by extended-spectrum β-lactamase producing Enterobacteriaceae in HIV infected persons as compared to healthy individuals in Nepal

A worldwide increase in the gastrointestinal colonization by extended-spectrum β-lactamase (ESBL)-producing bacteria has been observed. Their prevalence amongst Healthy People Living with HIV (HPLWH) has not been investigated adequately. The aim of this study was to determine and compare the rates of and risk factors for intestinal carriage and acquisition of extended-spectrum β-lactamase producing Enterobacteriaceae (ESBL-E) and carbapenemase-producing Enterobacteriaceae (CPE) among healthy people living with HIV (HPLWH) and healthy HIV negative population in the community. A cross-sectional study was conducted. Rectal swabs from HPLWH (n = 119) and HIV negative individuals (n = 357) from the community were screened for ESBL and CPE. Phenotypically confirmed ESBL-E strains were genotyped by multiplex PCR. The risk factors associated with ESBL-E colonization were analyzed by a multivariable conditional logistic regression analysis. Specimen from 357 healthy volunteers (213 female and 144 male) and 119 HPLWH (82 female and 37 male) with a median age of 30 [IQR 11–50] years were included in the study. ESBL colonization were found in 45 (37.82% [CI 29.09, 47.16]) and 246 (68.91% [CI 63.93, 73.49]), HPLWH and healthy HIV negative participants respectively. HPLWH had lower ESBL carriage rate (odds ratio 0.274 [CI 0.178, 0.423]) compared to healthy HIV negative subject’s (p<0.01). In this study, no carbapenemase-producing bacteria were isolated.CTX-M-15 type was the most predominant genotype in both groups. Livestock contact and over-the-counter medications were significantly associated with a higher ESBL-E carriage rate among healthy subjects. This is the first study in Nepal that has demonstrated a high rate of gut colonization by ESBL-E in the community, predominantly of blaCTX-M-15 genotype. This study divulges the low fecal carriage rate of ESBL producing bacteria in HPLWH group compared to healthy individuals in western Nepal. The factors responsible for this inverse relationship of HIV status and gut colonization by ESBL-E are unidentified and require further large-scale study.

Antibiotic-Resistant Infections and Treatment Challenges in the Immunocompromised Host

This article reviews antibiotic resistance and treatment of bacterial infections in the growing number of patients who are immunocompromised: solid organ transplant recipients, the neutropenic host, and persons with human immunodeficiency virus and AIDS. Specific mechanisms of resistance in both gram-negative and gram-positive bacteria, as well as newer treatment options are addressed elsewhere, and are only briefly discussed in the context of the immunocompromised host.

Multidrug Resistant CTX-M-Producing Escherichia coli: A Growing Threat among HIV Patients in India

Extended Spectrum β-Lactamases (ESBLs) confer resistance to third-generation cephalosporins and CTX-M types have emerged as the most prominent ESBLs worldwide. This study was designed to determine the prevalence of CTX-M positive ESBL-producing urinary E. coli isolates from HIV patients and to establish the association of multidrug resistance, phylogeny, and virulence profile with CTX-M production. A total of 57 ESBL producers identified among 76 E. coli strains isolated from HIV patients from South India were screened for bla_CTX-M, AmpC production, multidrug resistance, and nine virulence associated genes (VAGs), fimH, pap, afa/dra, sfa/foc, iutA, fyuA, iroN, usp, and kpsMII. The majority (70.2%) of the ESBL producers harbored bla_CTX-M and were AmpC coproducers. Among the CTX-M producers, 47.5% were found to be UPEC, 10% harbored as many as 7 VAGs, and 45% possessed kpsMII. Multidrug resistance (CIP^RSXT^RGEN^R) was significantly more common among the CTX-M producers compared to the nonproducers (70% versus 41.2%). However, 71.4% of the multidrug resistant CTX-M producers exhibited susceptibility to nitrofurantoin thereby making it an effective alternative to cephalosporins/fluoroquinolones. The emergence of CTX-M-producing highly virulent, multidrug resistant uropathogenic E. coli is of significant public health concern in countries like India with a high burden of HIV/AIDS.

Resistance Patterns of Escherichia coli in Women with Uncomplicated Urinary Tract Infection Do Not Correlate with Emergency Department Antibiogram

BACKGROUND

Urine cultures are not always performed for female Emergency Department (ED) patients with uncomplicated urinary tract infection (UTI). Accordingly, hospital, and even ED-specific, antibiograms might be skewed toward elderly patients with many comorbidities and relatively high rates of antimicrobial resistance, and thus do not accurately reflect otherwise healthy women. Our ED antibiogram indicates Escherichia coli resistance rates for ciprofloxacin, levofloxacin, and trimethoprim-sulfamethoxazole (TMP-SMX) of 42%, 26%, and 33%, respectively.

OBJECTIVES

This study aims to compare resistance rates of urinary E. coli from otherwise healthy women with uncomplicated UTI and pyelonephritis in the ED to rates in our ED antibiogram.

METHODS

Females > 18 years old with acute onset of urinary frequency, urgency, or dysuria with pyuria identified on urinalysis (white blood cell count > 10/high-power field) were prospectively enrolled in the ED of an urban, academic medical center. Exclusion criteria indicating a complicated UTI were consistent with Infectious Diseases Society of America guidelines. Susceptibility patterns of E. coli to ciprofloxacin, levofloxacin, and TMP-SMX in the study group were compared to our ED antibiogram.

RESULTS

Forty-five patients grew E. coli. Pyelonephritis was suspected in nine (20%) subjects. Compared with the ED antibiogram, significantly lower rates of resistance to ciprofloxacin (2% vs. 42%, p < 0.001), levofloxacin (2% vs. 26%, p < 0.001), and TMP-SMX (16% vs. 33%, p = 0.016) were observed. Six patients grew non-E. coli uropathogens. All were susceptible to both levofloxacin and TMP-SMX.

CONCLUSIONS

ED antibiograms may overestimate resistance rates for uropathogens causing uncomplicated UTIs. In cases where nitrofurantoin cannot be used, fluoroquinolones and possibly TMP-SMX may remain viable options for treatment of uncomplicated UTI and pyelonephritis in women.

Characterization of bacterial antimicrobial peptides active against Campylobacter jejuni

Campylobacter jejuni is one of the major causes of food poisoning, often resulting from the consumption of improperly cooked poultry products. The emergence of C. jejuni strains resistant to conventional antibiotics necessitates the evaluation of other possible treatments or preventative measures to minimize the impact and prevalence of infections. Antimicrobial peptides produced by bacteria have begun to emerge as a potential means of decreasing the levels of C. jejuni in poultry, thereby limiting Campylobacter contamination in associated food products. A number of bacteriocins produced by Gram-positive bacteria have unexpectedly been described as having antimicrobial activity against the Gram-negative C. jejuni. Additionally, some nonribosomal lipopeptides produced by Bacillus and Paenibacillus spp. show efficacy against this pathogen. This review will describe the bacterial antimicrobial peptides reported to be active against C. jejuni, with an emphasis on the characterization of their primary structures. However, for many of these peptides, little is known about their amino acid sequences and structures. Furthermore, there are unusual inconsistencies associated with the reported amino acid sequences for several of the more well-studied bacteriocins. Clarifying the chemical nature of these promising antimicrobial peptides is necessary before their potential utility for livestock protection from C. jejuni can be fully explored. Once these peptides are better characterized, they may prove to be strong candidates for minimizing the impact of Campylobacter on human health.