Jundishapur Journal of Microbiology
Volume:14 Issue: 9, Sep 2021

Based on the WHO, multidrug-resistant Klebsiella pneumoniae is a priority pathogen that causes opportunistic infections and is widely spread in the environment. Phage therapy is considered a natural, safe, and very efficient alternative to treat difficult-to-treat infections.

This study aimed to isolate highly virulent, lytic bacteriophages and evaluate their efficacy for lysing multidrug-resistant K. pneumoniae.

Municipal wastewater samples were collected and filtered using 0.22 µm syringe filters and cultivated with log-phase cultures of K. pneumoniae using enrichment media. After 48 h of incubation, the cultures were centrifuged, and the resultant supernatant was filtered (0.22 µm). The detection of the phage was done using the spot assay with K. pneumoniae as the host. One-step growth kinetics and bacterial reduction tests were conducted to assess the growth kinetics of the isolated phage. The stability of the isolated phage was characterized by subjecting it to various temperature and pH conditions. The chemical stability of the K. pneumoniae phage was determined by exposing it to various organic compounds. A panel of 20 bacterial strains was tested using the spot assay, as well as double agar overlying assay, to determine the host range of the isolated phage.

Out of 40 wastewater samples tested, only one sample was tested positive for the K. pneumoniae phage (2.5%) that was lytic against the host strain. The K. pneumoniae phage had a latent period of 15 min and a burst size of 100 virions per infected cell. It was most stable at 37°C and pH range of 6.0 to 10.0. Chemically, the K. pneumoniae phage was resistant to 10% chloroform treatment. Transmission electron micrograph indicated that the K. pneumoniae phage belonged to the order Caudovirales, family Siphoviridae, morphotype B1.

Most of the characteristic features of the K. pneumoniae phage indicated the potential of this phage to be used in phage therapy. Hence, a comprehensive study is highly recommended to characterize the K. pneumoniae phage genome, detect its molecular interactions with the host cell, and determine its lytic activity in combination with other phages, which may lead to the efficient utilization of this phage in phage therapy against K. pneumoniae infections.

Methicillin-resistant Staphylococcus aureus (MRSA) not only is a notorious pathogen in clinical settings but also is an environmental issue that its presence in environmental wastewater is highlighted by several reports. Due to the negative impacts of antibiotics, alternatives like bacteriophages, as biocontrol, are considered safe. However, not all bacteriophages are safe. Thus, the characterization of bacteriophages is necessary.

This study aimed to, firstly isolate MRSA from wastewater and, secondly to perform bacteriophage isolation from the water samples to investigate its physical and genomic characteristics.

Water samples were collected from seven locations across Nagpur city, India, bacteria were isolated on the S. aureus specific agar. For detecting MRSA, we followed the disc diffusion method. Isolation of bacteriophage against MRSA was performed by a modified enrichment method. We investigated its physical characteristics by the one-step growth rate, adsorption rate, host range, survivability, electron microscopy, and genomic sequencing for bioinformatics analysis.

Four MRSA were isolated from wastewater samples. We got a bacteriophage against an MRSA from the river Ganga. The bacteriophage belongs to the Podoviridae family, subfamily Autographivirinae. It was stable till 40°C and could survive at a highly alkaline pH. It is specific to its host. The bacteriophage DNA encodes 52 ORF, and all predicted genes are on the same strand; it also encodes a phage RNA polymerase.

It is the first report of an S. aureus bacteriophage that belongs to the sub-family Autographivirinae. Our study and literature survey conclude that S. aureus bacteriophages of the Podoviridae family are safe for various downstream applications.

The incidence of infection by Ralstonia is increasing. Several reports describing infection by these bacteria in immunocompromised patients have been published. In this study, we reported a case of Ralstonia pickettii infection in a patient with normal immunity.

A woman presented with fever after thyroid surgery. We identified R. pickettii in her blood culture using 16S rRNA gene sequencing. The patient’s condition improved clinically upon treatment with levofloxacin.

Our report highlights the potential of Ralstonia to cause sepsis in patients with normal immunity and emphasizes the importance of blood culture testing when a hospitalized patient has an unexplained high fever.

Asymptomatic carriage of Staphylococcus aureus can lead to endogenous infections and cross-transmission to other individuals.

The prevalence, molecular epidemiology, antibiotic resistance, and risk factors for nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) were studied in school children in Ardabil, Iran.

Totally, 510 nasal samples were collected during 2017. Isolates were identified and subjected to antimicrobial susceptibility testing, identification of oxacillin resistance, and molecular typing.

Totally, 13.5% of volunteers were positive for methicillin-susceptible Staphylococcus aureus (MSSA) and 17.5% colonized with mecA positive S. aureus strains, including 6.07% oxacillin-resistant MRSA (OR-MRSA) and 11.56% oxacillin-susceptible MRSA (OS-MRSA). Excluding β-lactam antibiotics, high resistance rate was observed for erythromycin (71%), tetracycline (25.8%), clindamycin (35%) in our isolates. Surprisingly, 11% of the isolates [OR-MRSA (25.8%), OS-MRSA (10.1%), and MSSA (5.7%) isolates] were resistant to mupirocin. Moreover, 18 (58%), 29 (49%), and 29 (42%) of OR-MRSA, OS-MRSA, and MSSA isolates were multidrug-resistant (MDR), respectively. Overall, 97.48% of isolates carried ≥ 3 toxin encoding genes. The pvl gene was found in 46 (29%) isolates. In comparison, 25.50% of MRSA (9.60% OR-MRSA and 34% OS-MRSA) and 33% of MSSA isolates carried pvl gene. SCCmec type IV had the highest rate among OR-MRSA (87%) and OS-MRSA (74.5%) isolates, which indicates CA-MRSA phenotype. Eleven and 21 spa types were identified in OR-MRSA, and OS-MRSA isolates, respectively. The most common spa types were t11332 (14.3%) and t012 (11.4%) in OS-MRSA isolates. ERIC-PCR revealed high genetic diversity among isolates. The number of students in classroom and incomplete antibiotic course were associated with OS-MRSA nasal carriage.

This study showed a high proportion of MDR CA-MRSA nasal carriage among Iranian healthy school children community.

It can be a critical point for reducing pathogen identification time and accurate antibiotic treatment for patients with blood circulation infection since it causes high mortality.

The objectives of this study were to evaluate the time differences between conventional identification and MALDI-TOF conventional identification and short-incubation MALDI-TOF identification for positive blood cultures, and to explore the impact of short-incubation MALDI-TOF identification on empirical antibiotic therapy.

Positive blood cultures were collected in our hospital from 2017 to 2019, clinical data were collected from the medical records, which were analyzed retrospectively to determine the empirical antibiotic therapy.

Compared with the conventional identification method, the short-incubation MALDI-TOF identification time to initial identification of Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecium, and E. faecalis decreased by 22.28 h, 22 h, 23.59 h, 23.63 h, 22.63 h, 23.92 h, and 21.59 h, respectively (P < 0.05). The time to final reporting was decreased by 48.85 h, 47.99 h, 55.40 h, 51.07 h, 49.60 h, 51.78h, and 51.73h, respectively (P < 0.05). However, the antimicrobial susceptibility test time of E. coli, A. baumannii, and S. aureus increased to 2.02 h, 2.19 h, and 3.86 h, respectively (P < 0.05). The coincidence rate of antimicrobial susceptibility was 98.48% between short-incubation MALDI-TOF identification and conventional identification method of all Gram-negative bacilli, and there were no extremely major errors or major errors. The coincidence rate of antimicrobial susceptibility of Gram-positive cocci was 99.53%, one strain of E. faecium and S. aureus had major errors. Patients received earlier correct empirical antibiotic 19.89 h earlier by short-incubation MALDI-TOF identification than the conventional identification method (P < 0.001).

The short-incubation MALDI-TOF identification significantly shortens the pathogen identification time and the final report time, it is a reliable method for rapid identification of positive blood cultures; the results of antimicrobial susceptibility are highly consistent, which significantly lead to earlier appropriate empirical therapy of bacteremia.

Uropathogenic Escherichia coli (UPEC) strains, encoding superficial and secretory virulence factors, can lead to colonization and facilitation of bacterial growth in the host urinary tract, causing Urinary Tract Infection (UTI).

This study determined the ability of biofilm formation by the Congo red agar (CRA) method, the presence of virulence genes using the multiplex polymerase chain reaction (PCR) method, and the relationship between biofilm formation and antibiotic resistance patterns and virulence genes in E. coli clinical isolates in Yasuj.

This cross-sectional study was performed on 144 UPEC isolates collected in 2017. Biofilm formation was detected by the CRA phenotypic assay and virulence factors by the multiplex PCR method. Antibiotic resistance tests were performed by the Kirby-Bauer method.

Out of 144 isolates of E. coli, 22 (19.4%) isolates showed to be strong biofilm producers, 27 (23.8%) moderate biofilm producers, and 64 (56.3%) weak biofilm producers. A significant relationship was observed between biofilm-producing strains and resistance to ampicillin (P = 0.020) and cotrimoxazole (P = 0.038). The virulence genes in strong biofilm producers included iutA (95%), FimH (93%), ompT (90%), PAI (90%), and TraT (81%) genes. The phylogroup B2 carried the most virulence genes. A significant correlation was observed between E. coli phylogenetic groups and aer (P = 0.019), iroN (P = 0.042), and ompT (P = 0.032) virulence genes.

The results of this study showed a high prevalence of virulence genes, and antibiotic-resistant E. coli strains capable of biofilm formation. The results of this study may help elucidate the pathogenesis of UPEC and facilitate better treatment strategies for patients with UTIs in this geographic area.