Detection and distribution of zoonotic pathogens in wild Norway rats (Rattus norvegicus) from Tehran, Iran.

This is the first study on the prevalence of vector-borne zoonotic pathogens found in Rattus norvegicus (R. norvegicus) in urban areas of Tehran, Iran. Serological tests were used to detect IgG antibodies against Coxiella burnetii (C. burnetii) and Rickettsia spp. using a commercial qualitative rat ELISA kit. The frequency of Streptobacillus moniliformis (S. moniliformis) and Bartonella spp. was determined using a conventional PCR method. Molecular detection and characterization of Leptospira spp. were conducted using TaqMan real-time PCR based on lipL32 gene and SecY typing methods. A total of 100 R. norvegicus rats were collected from five regions in Tehran, Iran, and investigated to determine their zoonotic pathogens. S. moniliformis and Bartonella spp. were detected in 23 of 100 (23%) and 17 of 100 (17%) R. norvegicus populations, respectively. The highest prevalence of S. moniliformis and Bartonella spp. with similar frequency rates (n = 6/20; 30%) was seen among the R. norvegicus rats captured from the northern and southern parts of Tehran, respectively. Seroreactivity against C. burnetii and Rickettsia spp. was detected in 4% and 1% of R. norvegicus, respectively. C. burnetii. was identified only in one rat captured from the eastern part of Tehran. Results showed that Leptospira spp. was detected only in two rats, collected from the southern part (n = 2/20; 10%) of Tehran. The secY typing method identified two different Leptospira species including L. interrogans and L. kirschneri. The results showed that urban rats might play an important role in transmission of zoonotic pathogens to humans.

Coagulase-negative staphylococci (CoNS) meningitis: a narrative review of the literature from 2000 to 2020.

Coagulase-negative staphylococci (CoNS) are recognized as comprising the main part of human normal microbiota and are rarely associated with severe and intensive infections. However, these organisms can cause a number of infections in humans, especially immunocompromised patients and neonates. Bacterial meningitis, as an important and acute infection in the central nervous system, is still a major global health challenge and a serious infectious disease, causing a high rate of mortality and morbidity. CoNS as causative agents of meningitis are generally related to trauma or direct implantation of foreign bodies and the presence of a cerebrospinal fluid shunt. Numerous epidemiologic and clinical studies have shown that different CoNS isolates such as Staphylococcus capitis, Staphylococcus lugdunensis, Staphylococcus hominis, Staphylococcus epidermidis, Staphylococcus schleiferi, Staphylococcus saprophyticus, Staphylococcus warneri and Staphylococcus haemolyticus are more frequently associated with meningitis. This study attempts to determine the role of CoNS in meningitis and reviews the reported cases of meningitis induced by CoNS from the year 2000 to 2020 in the literature.

Frequency of Mycoplasma pneumoniae, Legionella pneumophila and Chlamydia spp. among patients with atypical pneumonia in Tehran.

Mycoplasma pneumoniae, Legionella pneumophila and Chlamydia pneumoniae are the most common bacterial agents, which account for 15-40%, 2-15% and 5-10% of atypical community-acquired pneumonia (CAP) respectively. These agents are mostly associated with infection in the outpatient setting. The aim of this study was to evaluate the frequency of these pathogens among patients with CAP attending outpatient clinics in Tehran. A cross-sectional study was carried out of 150 patients attending to educational hospitals in Tehran with CAP. M. pneumoniae, L. pneumophila and Chlamydia spp. were detected by PCR assay, targeting the P1 adhesion gene, macrophage infectivity potentiator (mip) gene and 16S rRNA gene respectively from throat swabs obtained from each patient. A total of 86 (57.3%) of 150 patients were women; median age was 50 years (interquartile range, 35-65 years). M. pneumoniae, L. pneumophila and Chlamydia spp. were detected in 37 (24.7%), 25 (16.7%) and 11 (7.3%) patients respectively; of these, 66 patients (44%) were infected at least by one of these three pathogens. The frequency of L. pneumophila was significantly higher among patients over 60 years old (p 0.03). Coinfection was detected in seven patients (4.7%); six were infected by M. pneumoniae and L. pneumophila, and only one was infected by L. pneumophila and Chlamydia spp. M. pneumoniae was the most prevalent agent of atypical CAP, and L. pneumophila was more likely to infect elderly rather than younger people. Further studies on the prevalence of CAP and its aetiologic agents are needed to improve the diagnosis and treatment of CAP patients.

Molecular serotyping and genotyping of penicillin non-susceptible pneumococci: the introduction of new sequence types, Tehran, Iran.

The emergence of penicillin non-susceptible Streptococcus pneumoniae (PNSP) isolates can pose significant challenges to today's health-care system. Resistant clonal isolates are disseminated in different regions and countries, and this study was focused on the description of the epidemiological spread of these strains. Clinical samples were collected from individuals admitted to hospitals affiliated to the Tehran University of Medical Sciences, Iran. To investigate the molecular characteristics of PNSP isolates, they were subjected to molecular typing using multi-locus sequence typing (MLST). Serotype distributions of S. pneumoniae isolates were also evaluated by multiplex PCR assay. The most prevalent serotypes in the PNSP isolates were 23F, 19F, 14, 3 and 9V. Two isolates were considered as a non-vaccine serotype. The MLST analysis showed that PNSP isolates belonged to five different clonal complexes (CC180, CC217, CC81, CC63 and CC320) and 42% (5/12) of the sequence types were novel (12936, 12937, 12938, 12939 and 12940). This study indicates the high level of heterogeneity that is present among PNSP isolates. Unexpected high genetic diversity in small populations indicates consecutive diversification of resistant strains.

Methicillin-resistant Staphylococcus aureus tracking spread among health-care workers and hospitalized patients in critical wards at a university hospital, Tehran, Iran.

Health-care workers may serve as a reservoir for dissemination of methicillin-resistant Staphylococcus aureus (MRSA) to patients in hospital settings. The present study aimed to screen MRSA in nasal swabs of health-care workers and clinical specimens from patients and investigate the possible relationship between these isolates at a university hospital in Tehran, Iran. Additionally, we aimed to identify potential risk factors for MRSA colonization in health-care workers. Staphylococcus aureus strains were isolated from health-care workers and inpatients who completed a questionnaire on risk factors. Cefoxitin disc diffusion test was also used for detection of MRSA. Moreover, all of the MRSA isolates were subjected to pulsed-field gel electrophoresis (PFGE). Colonization rate of MRSA among health-care workers was 22.5%. Furthermore, out of 24 S. aureus isolates obtained from patients, nine (37.5%) were MRSA. Regarding risk factors, the prevalence of nasal MRSA carriage among hospital personnel who used masks was significantly lower than in those without masks (p 0.007). Using PFGE, 10 clusters and 14 singletons were identified among the MRSA isolates. In this regard, most of the MRSA isolates recovered from health-care carriers and patients in intensive care wards, especially general intensive care units, were grouped in certain clusters, indicating intra-ward transmission of the mentioned isolates in these restricted areas. We concluded that screening and decolonization of carriers, contact precautions, prudent use of antibiotics and implementation of active surveillance are recommended strategies for the prevention and control of MRSA transmission in hospital settings.

Identification of tigecycline- and vancomycin-resistant Staphylococcus aureus strains among patients with urinary tract infection in Iran.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major causes of hospital- and community-acquired infections worldwide. Although S. aureus rarely accounts for urinary tract infections (UTI), untreated UTI can lead to several complications. For decades vancomycin has been used for the treatment of MRSA infections. This study was performed to assess the in vitro activity of vancomycin, tigecycline, linezolid and quinupristin/dalfopristin against MRSA isolates from UTI patients. Thirty MRSA strains from 54 S. aureus isolates were isolated from patients with UTI. The antimicrobial susceptibility patterns of the strains were determined by the Kirby-Bauer disk diffusion and broth microdilution methods. PCR assays were used to detect the vanA gene. The MRSA isolates resistant to vancomycin were confirmed using the broth microdilution method. The results revealed that the MRSA isolates were 100% susceptible to linezolid and quinupristin/dalfopristin but 93.3% susceptible to vancomycin and tigecycline respectively. The broth microdilution method confirmed two MRSA strains (6.6%) to be resistant to vancomycin and tigecycline. The study identified vancomycin resistance among the MRSA isolates from UTI patients. This vancomycin resistance in MRSA isolates poses a challenge in managing S. aureus infections. Our study's results highlight the need to correctly identify patients in whom last-resort therapy such as linezolid and quinupristin/dalfopristin should be administered.

Phenotypic and genotypic study of biofilm formation in Enterococci isolated from urinary tract infections.

BACKGROUND: Urinary tract infection (UTI) is one of the most frequent types of nosocomial and community acquired infections in humans. Management of multidrug-resistant Enterococci UTI due to the limited therapeutic options is a great challenge for physicians and clinical microbiologists. The role of bacterial biofilms in recurrent urinary tract infections and antimicrobial resistance has great importance for public health. The aim of this study was to investigate the antibiotic susceptibility pattern as well as the phenotypic and genotypic biofilm formation ability of Enterococci isolates from patients with UTI. METHODS: A total of 57 isolates of Enterococci were collected from patients with UTI. Enterococcus species were identified using conventional microbiological methods. The antibiotic susceptibility patterns of the isolates were determined by the Kirby-Bauer disk-diffusion. The Modified Congo red agar (MCRA) and Microtiter plate methods used to assess the ability of biofilm formation. All enterococcal isolates were examined for determination of biofilm-related genes, esp, asa1 and ebpR using PCR method. RESULTS: Of 57 enterococcal isolates, 85.9% were recognized as E. faecalis and 14.1% of them were E. faecium. According to our results, linezolid, chloramphenicol and nitrofurantoin were the most effective agents against Enterococcus species. Overall, 26.5% of E. faecalis and 75% of E. faecium isolates were biofilm producers, respectively. Resistance to some antibiotics including penicillin G, ampicillin, vancomycin, nitrofurantoin and chloramphenicol, and ciprofloxacin was significantly higher among biofilm producers than non-biofilm producers Enterococci. The esp, asa1 and ebpR genes were present in 84.2%, 91.2% and 100% isolates. In this study, there was not a significant relationship between presence of these genes and biofilm formation. CONCLUSION: Our findings reinforce the role of biofilm formation in resistance to antimicrobial agents. Quinupristin/dalfopristin, tetracycline and rifampin may be used as an effective treatment for UTI caused by biofilm producers Enterococci. Our results suggest that biofilm formation is complex and depends on various factors but not just esp, asa1 and ebpR genes in Enterococcus strains.

A comparison between occlusive and exposure dressing in the management of burn wound.

BACKGROUND AND AIM: Two types of dressing, occlusive and exposure dressing, are commonly used in burn units. A dressing is said to be occlusive if a moist wound surface is maintained when the dressing is in place. This study was designed to compare the effectiveness of occlusive and exposure dressing in controlling burn infections. PATIENTS AND METHODS: Two hundred patients with second-degree burns admitted to Mottahari Hospital, Tehran, Iran, over a period of 12 months from May 2012 to May 2013 were studied. They were divided into two groups of 100 each, to receive either occlusive or exposure dressing. During the first week of treatment, wound specimens were obtained by sterile swab and cultured in selective media. Demographics (age and gender), burn areas, cause of burn, length of hospital stay (LOS), type of infections and time to total healing were compared between the two groups. RESULTS: Occlusive dressing was more susceptible to microbial contamination and infections than exposure dressing. The mean duration of treatment based on epithelialization and healing in occlusive dressing was longer than for exposure dressing. The most common isolate was Pseudomonas spp., followed by Enterobacter, Escherichia coli, Staphylococcus aureus, Acinetobacter, and Klebsiella spp. CONCLUSIONS: Exposure dressing was more suitable than occlusive dressing for treating partial-thickness at our center. Pseudomonas aeruginosa was the most common organism encountered in burn infection.

The antimicrobial effects and metabolomic footprinting of carboxyl-capped bismuth nanoparticles against Helicobacter pylori.

Organic salts of bismuth are currently used as antimicrobial agents against Helicobacter pylori. This study evaluated the antibacterial effect of elemental bismuth nanoparticles (Bi NPs) using a serial agar dilution method for the first time against different clinical isolates and a standard strain of H. pylori. The Bi NPs were biologically prepared and purified by a recently described method and subjected to further characterization by infrared spectroscopy and anti-H. pylori evaluation. Infrared spectroscopy results showed the presence of carboxyl functional groups on the surface of biogenic Bi NPs. These biogenic nanoparticles showed good antibacterial activity against all tested H. pylori strains. The resulting MICs varied between 60 and 100 µg/ml for clinical isolates of H. pylori and H. pylori (ATCC 26695). The antibacterial effect of bismuth ions was also tested against all test strains. The antimicrobial effect of Bi ions was lower than antimicrobial effect of bismuth in the form of elemental NPs. The effect of Bi NPs on metabolomic footprinting of H. pylori was further evaluated by (1)H NMR spectroscopy. Exposure of H. pylori to an inhibitory concentration of Bi NPs (100 µg/ml) led to release of some metabolites such as acetate, formic acid, glutamate, valine, glycine, and uracil from bacteria into their supernatant. These findings confirm that these nanoparticles interfere with Krebs cycle, nucleotide, and amino acid metabolism and shows anti-H. pylori activity.

Infectious complications after kidney transplantation: a single-center experience.

Infectious complications after renal transplantation are associated with significant morbidity and mortality. The prevalence of infections in transplant recipients varies from country to country. This study sought to assess the overall incidence of post-transplant infectious complications at our research center in Iran, compared with other centers in the world. Between 2002 and 2004, 179 renal transplantations were performed in our center. Of these, 142 were studied and followed for 1 year. Immunosuppressive regimens were cyclosporine, mycophenolate mofetil, and prednisolone. The overall incidence of infections was 54.2%. The most common sites of infections were the urinary tract (41.5%) and the respiratory tract (6.3%). The most frequent causes of infections were Klebsiella (24%) and cytomegalovirus (CMV) (17.6%). Wound infection occurred in 4.9% of the patients. Three (2.1%) patients developed hepatitis C and 2 (1.4%) had mycobacterial infections. There was no case of Pneumocystis pneumonia. Overall mortality was 7.7%. Infection-related mortality was 3.5%. In conclusion, this study identifies infections as the cause of morbidity and mortality in the post-transplant period. There was a low incidence of tuberculosis (<2% yearly) and a high incidence of CMV disease in our recipients.