Jundishapur Journal of Microbiology
Volume:12 Issue: 11, Nov 2019

Due to the difficulty of treatment caused by its numerous mechanisms of resistance, only four kinds of antibiotics are recommended for the therapy of Stenotrophomonas maltophilia infections associated with significant morbidity and mortality.

In this four-year study, we aimed to determine the evolution of drug resistance to S. maltophilia base on drug classification guidelines recommended by the Institute of Clinical and Laboratory Standards.

A total of 1876 strains of S. maltophilia was separated from multifarious clinical specimens among January 2016 and December 2019. VITEK 2 Compact microbial system was used for speciation level identification and antibiotic sensitivity test.

A total of 1876 strains of S. maltophilia strains were separated from sputum specimen type (70.63%), Followed by bronchial (6.18%), blood (4.16%), and bronchoalveolar lavage samples (4.32%). Moreover, 695 strains of S. maltophilia strains were separated from intensive care unit (ICU) department (37.05%), and then neurosurgery ward (10.66%), integrative Chinese and western medicine ward (7.25%), general surgery ward (6.66%). The results of minocycline antibiotic of S. maltophilia with a drug resistance rate of 0.3%. From 2016 to 2019, the resistance rate of cefoperazone/sulbactam decreased from 20.8% to 15.2%, the resistance rate of trimethoprim-sulfametoxasole decreased from 7.9% to 4.5%. The resistance rate of minocycline fluctuate in 0.0%% between 0.7%. However, the resistance rate of levofloxacin increased from 7.7% to 8.0%.

In this study, S. maltophilia was detected in a variety of specimen types of different clinical departments, with the most detected in ICU patients and sputum specimen. S. maltophilia was sensitive to minocycline and levofloxacin, but the situation of cefoperazone/sulbactam resistance was not optimistic. The results of this study indicate that minocycline is considered to be the most effective antibiotic for the treatment of S. maltophilia. Therefore, we still need to strengthen the drug resistance monitoring, timely acquisition of S. maltophilia drug resistance changes, and actively take effective measures to deal with the drug resistance of S. maltophilia.

Acute respiratory infection (ARI) is caused by human metapneumovirus (HMPV), respiratory syncytial virus type A and B (RSV-A, RSV-B), human parainfluenza viruses 1, 2, and 3 (HPIV-1, HPIV-2, and HPIV-3), influenza viruses A and B (IfV-A, IfV-B), and human coronaviruses (OC43/HKU1, NL63, 229E) worldwide.

This study was conducted to assess the causative agents of viral ARI among hospitalized adults by real-time PCR.

Clinical nasopharyngeal swabs of 112 patients including 55 (49.1%) males and 57 (50.89%) females with ARI were analyzed using multiplex real-time RT-PCR.

Out of 112 specimens, 61 (54.46%) were positive including 10 (8.9%) for influenza H3N2, one (0.89%) for influenza B, 28 (25%) for RSV-A, 18 (16.07%) for HMPV-A, two (1.78%) for HPIV-1, and three (2.67%) for HPIV-3. Two (1.78%) specimens were positive for two agents, RSV-A/HMPV-A and RSV-A/HPIV-3. The distribution of viral infections was 30 among males (26.78%) and 31 (27.67%) among females (P = 0.862). High frequency of RSV-A infection (25%) and the low frequency of influenza B virus infection (0.89%) were detected among patients. The remaining 51 (45.53%) samples were negative for RSV-B, HMPV-B, IfV-A, HPIV2-4A-4B, and HCoVs (OC43/HKU1, NL63, 229E).

The role of other viruses such as human adenoviruses rhinovirus/enterovirus (RV/EV), human bocavirus (HBoV), and human parechovirus (HpeV) was not investigated. Multiplex PCR can be used as a rapid test for the diagnosis of viruses causing acute respiratory infection, which results in decreased length of hospitalization.

Zika Virus (ZIKV) is a new type of flaviviruses transmitted by mosquitoes to cause severe diseases including Guillain-Barré syndrome and congenital malformations during recent outbreaks. The early diagnosis of ZIKV infection and efficient vaccines would be effective in controlling epidemics and timely treatment. However, the native nonstructural protein 1 (NS1) mainly acquired from cells infected with ZIKV, which largely limits its application.

This study aimed to express and purify the recombinant NS1 protein and prepare its antibody that efficiently reacted with the native NS1 protein secreted in the supernatant of ZIKV infected host-cells.

We constructed a prokaryotic expression vector containing the full length of the NS1 gene. Thus, the recombinant NS1 protein was efficiently expressed and purified. The purified NS1 protein was used to prepare an antibody. The Enzyme-linked Immunosorbent Assay (ELISA), Western blot, and Indirect Immunofluorescent Assay (IFA) were used to assess the reactivity and specificity of the antibody.

The recombinant NS1 protein from a prokaryotic expression vector had good immunogenicity and the prepared antibody could specifically react with the native NS1 produced in Vero, BHK-21 cells infected with ZIKV. Besides, the ELISA and Western blot showed that the native ZIKV-NS1 protein was secreted extracellularly and could play the role of an early diagnostic biomarker for ZIKV infection.

The prepared antibody against the recombinant NS1 protein is a reliable biological tool that enables the rapid and sensitive detection of secreted NS1 from host cells infected with ZIKV. The recombinant NS1 protein and its antibody can contribute to developing vaccines and antibodies targeting the NS1 protein to prevent flavivirus disease progression.

Mycobacterium tuberculosis is a pathogen that causes Tuberculosis and can invade various organs in infected patients. Its high morbidity and high mortality seriously threaten human health. In recent years, the continuous emergence of drug-resistant Tuberculosis bacteria has brought severe challenges to the prevention and control of Tuberculosis.

This study aimed to characterize the most frequent mutations of the katG, inhA, and ahpC genes in isoniazid (INH)-resistant M. tuberculosis clinical isolates in Shanghai Pulmonary Hospital, China, and investigate the relationship between gene mutations and the minimum inhibitory concentrations (MICs) of INH against M. tuberculosis.

We collected 92 INH-resistant and 30 INH-susceptible clinical isolates of M. tuberculosis. The drug resistance profiles of M. tuberculosis clinical isolates against common anti-tuberculosis drugs were determined and sequencing analysis was performed.

Of 92 INH-resistant strains, mutations in the katG and inhA genes were observed in 64 (69.6%) isolates and five (5.4%) isolates, respectively, and only had one (1.1%) strain both katG and inhA mutations. Among them, 62 (67.4%) strains carried a single mutation at codon 315 of the katG gene and a new mutation site was found in the katG gene of two strains. We detected a single mutation site at codon 271 and three simultaneous mutation sites at codons 315, 431, and 439. Only one (3.3%) of the 30 isoniazid-sensitive strains had the katG mutation. The AhpC mutation was detected in no experimental strains. The KatG Ser 315 Thr (AGC315ACC) mutation occurred in 53 (68.8%) out of 77 strains with high MICs (≥ 1 g/mL) of isoniazid-resistant M. tuberculosis while five (33.3%) out of 15 strains with low MICs (less than 1 g/mL) had katG Ser 315 Thr (AGC315ACC) mutation.

Isoniazid-resistant strains were dominated by Ser315 → Thr (AGC → ACC) substitution, which seems to be associated with multidrug resistance and high-level resistance to INH. Multisite mutations are related to multidrug-resistant M. tuberculosis and the discovery of new mutation sites provides a new basis for the detection of drug-resistant M. tuberculosis.

Atypical pneumonia is an upper and lower respiratory tract infection. Mycoplasma pneumoniae is a major cause of community-acquired pneumonia (CAP).

The present study aimed to determine the prevalence of atypical pneumonia caused by M. pneumonia by culture and molecular PCR methods in Tehran.

In the present study, 102 samples of throat swab were collected from patients with respiratory infections. All samples were cultured in liquid PPLO Broth And solid PPLO agar media (1% glucose and 20% horse serum). The PCR technique with specific primers was implemented after culture and genome extraction through phenol-chloroform technique.

In this study, 27 (26.47%) colonies of Mycoplasma were isolated on PPLO agar medium. Using specific primers, it was found that 33 samples (32.4%) were positive in terms of Mycoplasma genus and 14 samples (13.7%) were positive for the presence of M. pneumonia.

Mycoplasma pneumonia is a pathogen that causes respiratory tract infections in humans. Molecular PCR method is a quick and sensitive technique that has higher sensitivity and specificity than other methods. The obtained results may contribute to the specific treatment of some patients with symptoms of respiratory infections.

Staphylococcus aureus is one of the main causes of a wide range of nosocomial infections, like the infection of the skin and soft tissue.

The present study aimed to investigate the occurrence of antibiotic resistance and the presence of class 1-3 integrons in S. aureus strains isolated from hospitalized patients.

This cross-sectional study was carried out during six months in two major hospitals in southwestern Iran. Totally, 134 isolates of S. aureus were identified by phenotypic and molecular methods. A disk diffusion method was used to determine the antibiotic resistance pattern of S. aureus isolates. The detection of integron-encoding genes was performed by the PCR method.

Based on antibiotic susceptibility testing, 58 (43.2%) of 134 isolates of S. aureus were reported as methicillin-resistant S. aureus (MRSA) using cefoxitin disc diffusion and mecA gene detection. The highest resistance was seen to tetracycline (48.5%). The results were analyzed by the chi-square test and there was a significant difference (P value < 0.05) between antibiotic resistance in methicillin-sensitive S. aureus (MSSA) isolates. Molecular analysis showed that 53 (39.6%), 5 (3.7%), and none of the isolates were positive for class 1, 2, and 3 integrons, respectively.

The results indicated the remarkable rate of class 1 integrons in the clinical isolates of S. aureus in our region and the importance of investigating the prevalence of antibiotic resistance among them. However, these data alone cannot confirm the association between integrons and the presence of antibiotic resistance genes.