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Abstract

Increase in antibiotic resistance in Staphylococcus aureus isolated from ear infection is a serious public health problem. The objective of this investigation was to determine the antibacterial resistance profile and genetic variability of the S. aureus isolated from adult patients with otitis externa (OE) and otitis media (OM) infections, Tehran- Iran. The disk diffusion was employed to detect the susceptibility of 45 S. aureus strains. Biofilm production was evaluated by microtiter plate assay. Genetic diversity of the isolates was determined by staphylococcal cassette SCCmec, spa, and MLST techniques. Resistance to mupirocin and vancomycin were identified in 40 and 2.2% of isolates. Out of the 45 S. aureus isolates, 41 (91.2%) strains were considered as positive biofilm strains at different levels. According to our results, S. aureus isolated from OM (44.4%, 20/45) were including CC8/ST239-SCCmecIII corresponded to spa types t860, t030, t037, t234, t421 (70%, 14/20) and CC/ST30-SCCmecIV corresponded to spa types t605 and t019 (30%, 6/20) while S. aureus isolated from OE (55.6%, 25/45) were including CC/ST30-SCCmecIV corresponded to spa types t605, t345 and t1130 (52%, 13/25), CC/ST22-SCCmecIV corresponded to spa type t790 (20%, 5/25), CC8/ST8-SCCmecIV corresponded to spa type t008 (16%, 4/25), and CC/ST45-SCCmecIV corresponded to spa types t004 and t038 (12%, 3/25). This study highlighted genetic variability and strong biofilm formation ability among our isolates revealing its crucial role in enhancing the resistance of this bacteria to drugs. Thus, it is necessary to continue the epidemiological analysis to improve the control of ear infections related to S. aureus.

Abstract

The literature on fusidic acid resistant Staphylococcus aureus strains is scarce in Iran, although the emergence of these strains in health care settings is increasing. This descriptive cross-sectional study was conducted on 68 fusidic acid resistant S. aureus strains to learn about the molecular characteristics and antimicrobial resistance of strains isolated from hospitalized patients. In the present study, the prevalence of resistance to fusidic acid in S. aureus isolates was 15.1%. Fusidic acid resistance determinative factors (fusB, fusC and fusD) were identified by multiplex PCR assay. To detect the existence of fusA and fusE determinants and their mutation status, amplifications and sequencing were performed. Molecular characterization of fusidic acid resistant isolates was investigated by SCCmec and spa typing methods. All strains were MRSA and multi drug resistant. Two (2.9%) and 31 (45.6%) isolates were resistant to vancomycin and mupirocin respectively. The SCCmec type IV was highly prevalent representing 50% followed by types III (51.5%), and SCCmec types II (13.2%). fusB, was the most predominant acquired gene (66.2%) followed by fusC (19.1%), and fusA (14.7%). The mutations in fusA were present in 10 isolates with 5 (50%) having L461K mutation showing fusidic acid MIC values of ≥256 μg ml⁻¹ followed by H457Y (40%), and H457Q (10%) showing fusidic acid MIC values of 128 and 64 μg ml⁻¹ respectively. Isolates were allocated to ten particular t030 (22.1%), t037 (14.6%), t408 (11.8%), t064 (11.8%), t008 (10.3%), t002 (8.8%), t005 (5.9%), t790 (5.9%), t318 (4.4%), and t018 (4.4%) spa types. fusA positive isolates were assigned to particular spa types t002 (60%), and t005 (40%). There may be be a spreading of fusidic acid resistance among MRSA, creating worrying public concern. This research notes the importance of adequate data of local prevalence of FA-resistant MRSA in Iran for taking appropriate measures to treat, control and reduce the incidence of these isolates.

Abstract

The prevalence of Streptococcus agalactiae infections in adult populations is increasing. The current study aimed to characterize the genetic features of S. agalactiae strains responsible for different infections. A cross-sectional study was performed on 65 S. agalactiae strains (30 invasive and 35 noninvasive) isolated from non-pregnant women. All S. agalactiae isolates were confirmed by atr and dltS PCR assays. Antibiotic susceptibility patterns were determined using the disk diffusion method. Biofilm production was investigated by microtiter plate assay. PCR was done to detect resistance determinants. Isolates were characterized using the multilocus sequence typing (MLST) method. cMLS_B, iMLS_B, and M phenotypes accounted for 47.7%, 30.8%, and 6.2%, respectively. MDR was detected in 15.4% of noninvasive and 44.6% of invasive isolates. MtP assay indicated that 80% of isolates were biofilm producers. Biofilm formation was common among noninvasive compared with invasive strains (94.3% versus 66.7%). tet (M) (46.2%) and erm (B) (69.2%) were the most prevalent tetracycline and macrolide-resistance genes. The most prevalent serotype was type III (50.8%), followed by Ia (18.4%), II (15.4%), V (12.3%), and IV (3.1%). The frequency of serotype III among biofilm producer strains (81.8%) was found to be significantly higher than that of non-producer isolates (18.2%) (P < 0.05). S. agalactiae was resolved within four clonal complexes, including CC19 (46.2%; in both invasive and noninvasive), followed by CC23 (30.8%; only noninvasive isolates), CC1 (15.4%; only noninvasive isolates) and CC17 (7.6%; only invasive isolates). The main sequence types (STs) found were ST19 (27.7%), ST17 (7.7%), ST27 (6.2%), and ST28 (4.6%) linked with invasive infections and ST23 (18.4%), ST933 (12.3%), ST644 (9.2%), ST19 (7.7%), ST1 (6.2%) found in noninvasive infections. The high prevalence of CC19 and CC23 clones among S. agalactiae strains reflects the emergence of these lineages as successful clones in Iran.

Abstract

Although mobile phones as a rapid communication vehicle can lead to improved quality of healthcare, they can also facilitate the transmission of pathogens to patients. This current research focuses on genetic diversity, and genes involved in resistance and biofilm production of Staphylococcus aureus isolates from mobile phones of medical students. Antibiotic resistance profiling and polymerase chain reaction (PCR) amplification of antibiotic resistance and biofilm-related genes were investigated and statistically analyzed. Staphylococcal cassette chromosome mec (SCCmec) types were analyzed by multiplex PCR, and S. aureus protein A gene typing (spa typing) was done using PCR and sequencing. Sixty-four S. aureus isolates (16.8%) were obtained from 380 medical students' mobile phones who were working in hospitals. The findings showed that 71.9% of the isolates were MRSA and 78.1% were classified as MDR. All isolates exhibited sensitivity to vancomycin and linezolid. Overall, 7.8% of the isolates displayed an inducible clindamycin resistance phenotype, while 26.7% showed resistance to mupirocin. The results indicated that 68.8% of the isolates were biofilm producers, with 7 isolates (15.9%) classified as strong producers, 22 isolates (50%) as moderate producers, and 15 isolates (34.1%) as weak producers. The most prevalent type was CC8-MRSA III/t030 (18.7%), followed by CC8-MRSA III/t037 (12.5%), CC/ST22-MSSA/t790 (10.9%), CC1-MRSA IV-t114 (9.4%), CC1-MRSA IV-t127 (7.8%), CC8-MRSA V/t064 (7.8%), CC/ST15-MSSA-t360 (7.8%), CC30-MSSA/t021(6.3%), MRSA V-t355 (6.3%), CC8-MRSA III/t421 (4.7%), CC1-MRSA V-t267 (4.7%), and CC/ST15-MSSA-t084 (3.1%). The genetic diversity and prevalent multidrug resistance indicate that the resistance situation of S. aureus recovered from mobile phones in Tehran is severe, posing a potential threat to patients, the community, and healthcare settings.

Abstract

Early diagnosis of tuberculosis (TB), followed by effective treatment, is the cornerstone of global TB control efforts. An estimated 3 million cases of TB remain undetected each year. Early detection and effective management of TB can prevent severe disease and reduce mortality and transmission. Intrinsic and acquired drug resistance of Mycobacterium tuberculosis (MTB) severely restricted the anti-TB therapeutic options, and public health policies are required to preserve the new medications to treat TB. In addition, TB and HIV frequently accelerate the progression of each other, and one disease can enhance the other effect. Overall, TB-HIV co-infections show an adverse bidirectional interaction. For HIV-infected patients, the risk of developing TB disease is approximately 22 times higher than for persons with a protective immune response. Analysis of the current TB challenges is critical to meet the goals of the end TB strategy and can go a long way in eradicating the disease. It provides opportunities for global TB control and demonstrates the efforts required to accelerate eliminating TB. This review will discuss the main challenges of the TB era, including resistance, co-infection, diagnosis, and treatment.

Abstract

Carbapenems are employed to treat infections caused by Gram-negative bacteria including Klebsiella pneumoniae. This research is aimed to perform phenotypic detection of β-lactamases and molecular characterization of NDM-1 positive K. pneumoniae isolates. Another objective is to investigate NDM-1 producing K. pneumoniae among children in Iran. From 2019 to 2020, altogether 60 K. pneumoniae isolates were acquired from various patients in certain Iranian hospitals. Antimicrobial susceptibility testing was performed by disk diffusion and broth microdilution methods. In addition, mCIM and eCIM were used to confirm the production of carbapenemases and metallo-beta-lactamases (MBLs), respectively. Detection of resistance genes namely, bla _NDM-1, bla _IMP, bla _VIM, bla _KPC, bla _OXA-48-like, bla _CTX-M, bla _SHV, bla _TEM, and mcr-1 was performed by PCR and confirmed by DNA sequencing. Multilocus sequence typing (MLST) was employed to determine the molecular typing of the strains. According to the findings, the highest rate of carbapenem resistance was detected against doripenem 83.3% (50). Moreover, 31.7% (19) were resistant to colistin. Further to the above, altogether 80% (48) were carbapenemase-producing isolates and among them 46.7% (28) of the isolates were MBL and 33.3% (20) isolates were serine β-lactamase producer. According to the PCR results, 14 isolates produced bla _NDM-1. Remarkably, four bla _NDM-1 positive isolates were detected in children. In addition, these isolates were clonally related as determined by MLST (ST147, ST15). Altogether ten bla _NDM-1 positive isolates were ST147 and four bla _NDM-1 positive isolates were ST15. Based on the results, the emergence of NDM-producing K. pneumoniae among children is worrying and hence, it is necessary to develop a comprehensive program to control antibiotic resistance in the country.

Abstract

Staphylococcus aureus as an opportunistic bacterial pathogen with intrinsic and acquired resistance to many antibiotics is a worldwide problem. The current study was undertaken to evaluate the resistance pattern, and determine the genetic types of multidrug-resistant S. aureus isolated from wound.

This cross-sectional study was conducted over the period of two years (from December 2018 to November 2020) at the hospitals affiliated to Shahid Beheshti University of Medical Sciences, Tehran, Iran. In present study, 75 multidrug-resistant S. aureus isolates collected from wound infections were investigated. Phenotypic resistance was assessed by Kirby–Bauer disk diffusion method. Conventional PCR was performed for the detection of virulence encoding genes. Genotyping of strains was performed based on coa gene polymorphism using multiplex-PCR assay. SCCmec typing, spa typing and MLST were also used to characterize the genotype of the mupirocin, tigecycline and vancomycin resistant multidrug-resistant S. aureus isolates.

All 75 multidrug-resistant S. aureus isolates in the study were confirmed as MRSA. Coagulase typing distinguished isolates into five genotypic patterns including III (40%), I (24%), IVb (16%), V (10.7%) and type X (9.3%). Resistance to tigecycline was detected in 4% of MDR-MRSA isolates and all belonged to CC8/ST239- SCCmec III/t421 lineage. According to our analysis, one VRSA strain was identified that belonged to coa type V and CC/ST22-SCCmec IV/t790 lineage. Resistance to mupirocin was detected in 9.3% of strains. All 7 mupirocin resistant MDR-MRSA isolates exhibited resistance to mupirocin in high level. Of these, 4 isolates belonged to CC/ST8-SCCmec IV/t008 (57.1%), 2 isolates belonged to CC/ST8-SCCmec IV/t064 (28.6%) and one isolate to CC/ST22-SCCmec IV/t790 (14.3%).

Altogether, current survey provides a snapshot of the characteristics of S. aureus strains isolated from patients. Our observations highlighted type III as predominant coa type among multidrug-resistant MDR strains indicating low heterogeneity of these isolates. Our study also indicates the importance of continuous monitoring of the genotypes of MDR-MRSA isolates to prevent nosocomial outbreaks and the spread of MDR isolates.

Abstract

In this study, we focused on the emergence of extensively drug-resistant (XDR), pandrug-resistant (PDR), and hypervirulent Klebsiella pneumoniae (hvKP) in Iran. During 2018 to 2020 a total of 52 K. pneumoniae isolates were collected from different clinical specimens. The hvKP isolates were identified by PCR amplification of virulence and capsular serotype-specific genes. Hypermucoviscous K. pneumoniae (hmKP) were identified by string test. Carbapenem-resistant hvKP (CR-hvKP), multidrug-resistant hvKP (MDR-hvKP), extensively drug-resistant hvKP (XDR-hvKP), and pandrug-resistant hvKP (PDR-hvKP) were determined by disc diffusion method, Carba-NP test and PCR method. XDR-hvKP isolates were typed by multilocus sequence typing (MLST). Among all K. pneumoniae isolates 14 (26.9%) were identified as hvKP and 78.6% (11/14) of them were hmKP however, none of the classic K. pneumoniae (cKP) isolates were hmKP. The predominant capsular serotype of hvKP was K2 (42.85%) followed by K1 (35.71%). The prevalence of MDR-hvKP, XDR-hvKP and PDR-hvKP isolates were 6 (42.9%), 5 (35.7%) and 1 (7.1%), respectively. ESBL production was found in 85.7% of hvKP isolates and most of them carried bla _TEM gene (78.6%) and 6 isolates (42.9%) were CR-hvKP. Among hvKP isolates, 1 (7.1%), 2 (14.3%), 3 (21.4%), 8 (28.6%), and 11 (78.6%) carried bla _NDM-6, bla _OXA-48, bla _CTX-M, bla _SHV, and bla _TEM genes, respectively. According to MLST analysis, 2, 1, 1, and 1 XDR-hvKP isolates belonged to ST15, ST377, ST442, and ST147, respectively. The occurrence of such isolates is deeply concerning due to the combination of hypervirulence and extensively drug-resistance or pandrug-resistance.

Abstract

A major challenge in the treatment of infections has been the rise of extensively drug resistance (XDR) and multidrug resistance (MDR) in Acinetobacter baumannii. The goals of this study were to determine the pattern of antimicrobial susceptibility, bla _OXA and carO genes among burn-isolated A. baumannii strains. In this study, 100 A. baumannii strains were isolated from burn patients and their susceptibilities to different antibiotics were determined using disc diffusion testing and broth microdilution. Presence of carO gene and OXA-type carbapenemase genes was tested by PCR and sequencing. SDS-PAGE was done to survey CarO porin and the expression level of carO gene was evaluated by Real-Time PCR. A high rate of resistance to meropenem (98%), imipenem (98%) and doripenem (98%) was detected. All tested A. baumannii strains were susceptible to colistin. The results indicated that 84.9% were XDR and 97.9% of strains were MDR. In addition, all strains bore bla _OXA-51 like and bla _OXA-23 like and carO genes. Nonetheless, bla _OXA-58 like and bla _OXA-24 like genes were harbored by 0 percent and 76 percent of strains, respectively. The relative expression levels of the carO gene ranged from 0.06 to 35.01 fold lower than that of carbapenem-susceptible A. baumannii ATCC19606 and SDS – PAGE analysis of the outer membrane protein showed that all 100 isolates produced CarO. The results of current study revealed prevalence of bla _OXA genes and changes in carO gene expression in carbapenem resistant A.baumannii.