Molecular characterization of Staphylococcus aureus isolated from children with adenoid hypertrophy: emergence of new spa types t7685 and t7692

Distribution and Characteristics of Bacteria Isolated from Cystic Fibrosis Patients with Pulmonary Exacerbation

Background

Cystic fibrosis (CF) is an inherited recessive disorder characterized by recurrent and persistent pulmonary infections, resulting in lung function deterioration and early mortality.

Methods

A cross-sectional study was conducted on the bacterial profile and antibiotic resistance pattern of 103 respiratory specimens from CF patients with signs of pulmonary exacerbation. Antibiotic susceptibility testing and biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa isolates were performed by the Kirby-Bauer disc diffusion method and microtiter plate assay, respectively. Molecular typing of S. aureus and P. aeruginosa isolates was carried out by spa typing and repetitive extragenic palindromic element PCR.

Results

In a total of 129 isolates, the most prevalent organisms were S. aureus (55.3%) and P. aeruginosa (41.7%). Other less prevalent bacterial isolates include coagulase-negative staphylococci, Escherichia coli, klebsiella spp., Enterobacter spp., and Achromobacter xylosoxidans. The highest rate of resistance for S. aureus was observed to azithromycin and erythromycin (80%), ciprofloxacin (52.3%), clindamycin (44.6%) and tetracycline (43%). Twenty percent of S. aureus isolates were methicillin-resistant S. aureus (MRSA) and 47.6% were MDR S. aureus. For P. aeruginosa isolates the highest resistance was to cefepime (38.3%) and levofloxacin (33.3%) and 20% showed MDR phenotype.

Conclusion

Our study demonstrated a significant decline in the prevalence of P. aeruginosa infections in comparison to previous studies. We found S. aureus to be more prevalent in younger patients, whereas mucoid P. aeruginosa showed a shift in prevalence toward older ages. Molecular typing methods showed great diversity between isolates.

Phenotypic and genotypic determinants of mupirocin resistance among Staphylococcus aureus isolates recovered from clinical samples of children: an Iranian hospital-based study

Backgrounds

The aim of this study was to evaluate both phenotypic and genotypic determinants of mupirocin resistance among methicillin-resistant Staphylococcus aureus (MRSA) and methicillin susceptible S. aureus (MSSA) strains recovered from different clinical samples of children who were admitted to the Children’s Medical Center (CMC) Hospital, Tehran, Iran.

Materials and methods

A total of 120 clinical isolates of S. aureus were collected from the microbiology laboratory of CMC Hospital. Antimicrobial susceptibility of the isolates to different antimicrobial agents was determined by disk diffusion method. The methicillin resistance phenotype (MRSA) was identified using a 30 µg cefoxitin disk. The minimum inhibitory concentration (MIC) of mupirocin was determined by broth microdilution method. Strains with mupirocin MIC between 8 and 256 µg/mL were considered as low-level mupirocin resistant (LLMR), and strains with an MIC≥512 µg/mL were considered as high-level mupirocin resistant (HLMR). The presence of genes encoding HLMR (ie, mupA and mupB genes) was evaluated by PCR method.

Results

Four out of 120 isolates (3%) had mupirocin MIC≥512 µg/mL and were HLMR; however, no LLMR isolate was detected. Fifty-two isolates (43%) were MRSA, and there were no differences in the distribution of mupirocin resistance among MRSA and MSSA isolates (P>0.05). The PCR method identified mupA gene in two out of four HLMR isolates, and mupB gene was not detected in any HLMR isolates.

Conclusion

Because of discrepancies between the phenotypic and genotypic patterns of mupirocin resistance and due to the avoidance of false-negative results, it is better to determine the mupirocin resistance by both antibiotic susceptibility tests and PCR method. Considering the increasing need of mupirocin for the control of S. aureus infections, continuous checking of its susceptibility status is necessary.

Relation between adenoid size and otitis media with effusion

AIMS

This study compares the efficacy of adenoidectomy on otitis media with effusion (OME) in patients with different size of adenoids and the connection between differently sized adenoids and middle ear effusion.

MATERIAL AND METHODS

Children with a history of at least 3 months' OME underwent adenoidectomy and myringotomy without the insertion of a tympanostomy tube. Treatment assignment was stratified by adenoids' size causing choanal obstruction (grade I-III) and according to Eustachian tube ostium obstruction (grade A-C). The subjects were followed for 12 months.

RESULTS

Adenoidectomy was significantly more effective in children with adenoids in contact with torus tubarius (grade B, C) compared to those with small adenoids without contact (P<0.001). The volume of the adenoids was irrelevant (P=0.146). The size of adenoids did not affect the viscosity of the middle ear secretion. The distribution of mucous and serous secretion was not dependent on the size of adenoids; the efficacy of adenoidectomy was 82% in mucous as well as serous secretion.

CONCLUSION

The relation between adenoids and torus tubarius is more important than the volume of the adenoids. The viscosity of middle ear fluids (serous or mucous) did not influence the rate of treatment efficacy.

Genotypic characterization of Staphylococcus aureus isolated from a burn centre by using agr, spa and SCCmec typing methods

Infections caused by Staphylococcus aureus remain a major global healthcare problem. We aimed to find the common lineages of S. aureus strains circulating in a burn hospital in Tehran. A total of 167 isolates of S. aureus obtained from patients, healthcare workers (HCWs) and environment in Shahid Motahari burn hospital were genotyped by using spa, agr and staphylococcal cassette chromosome mec (SCCmec) typing methods. Antimicrobial susceptibility testing was performed by using the disc diffusion method. The frequency of methicillin-resistant S. aureus (MRSA) was 64.7% (n = 108), with distribution frequencies among patient, HCW and surface isolates of 64.2% (n = 79), 50% (n = 7) and 73.3% (n = 22), respectively. SCCmec type III (75%, n = 81) was found to be the most frequent SCCmec type among MRSA isolates, followed by SCCmec type I (20.4%, n = 22) and SCCmec type IV (1.8%, n = 2). The remaining MRSA isolates (2.8%, n = 3) were nontypeable by this method. About 78.4% (n = 131), 10.2% (n = 17) and 4.8% (n = 8) of all isolates were characterized as agr types I, II and III, respectively, and the other isolates (6.6%) were nontypeable. spa types t030 and t037 constituted the first and second most predominant spa types found in 56.4% (n = 57) and 25.6% (n = 26) of isolates, respectively. We also report here a novel spa type, t16471. The most prevalent genotypes of the isolates found among patient, surface and HCW samples were SCCmec type III/t030, t037/agr type I. Continuous tracking of epidemic isolates and better hospital infection control policies are recommended to efficiently prevent the spread of bacteria to inpatients.

Halitosis in children with adenoid hypertrophy

This paper attempts to identify the sources and evaluate the prevalence of halitosis in children with adenoid hypertrophy. The study included pediatric patients admitted for adenoidectomy due to obstructive symptoms. Patients with possibly other causes of halitosis, were excluded from the study. Halitosis was detected in 30 out of 136 children (22.1%). The effect of adenoid hypertrophy on halitosis was confirmed by the significant reduction in the organoleptic score rated according to the Rosenberg scale (on average by 2°) and the levels of volatile sulfur compounds (on average 84 ppb) post-adenoidectomy, as compared to pre-surgery results. In total, we reported a statistically significant decrease in the abovementioned values in 90% of patients with halitosis. It was found that in patients with halitosis, as compared to patients with no oral malodor, anaerobic bacteria and Staphylococcus aureus were more frequently observed in the adenoid tissue. Streptococcus oralis strains were more commonly reported in the material taken during adenoidectomy in children without oral malodor.

Antibiotic Resistance Patterns and Virulence Determinants of Different SCCmec and Pulsotypes of Staphylococcus Aureus Isolated from a Major Hospital in Ilam, Iran

Aims & Objectives:

The aim of this study is to evaluate genetic relatedness, antibiotic resistance pattern, and virulence characteristics of different types of S. aureus isolated from air, surfaces, staff, and patients in a Public hospital in Ilam.

Methods & Materials:

A total of 88 of 140 staphylococci identified as S. aureus by conventional and molecular methods were used in this study. Isolate samples were obtained from surfaces, staff, patients, and hospital indoor air. The sampling from staff and surfaces was done through using swab and air by standard pump. Antimicrobial susceptibility testing and presence different resistant and virulence determinants was assessed. Isolates were then typed by pulsed-field gel electrophoresis (PFGE) and SCCmec typing methods.

Results:

Out of 88isolates, 36 of them (40.9%) were MRSA. Among MRSA isolates, the range of resistance to antibiotic was 0% in vancomycin to 83.3% in gentamycin. The most prevalent resistant genes among gentamicin resistant S. aureus were acc (6')/aph (2”)Ia and aph(3”)IIIa. The most common erythromycin resistant gene was ermC. Surprisingly, SCCmec types I (30.5%), II (25%)were highly distributed. PFGE analysis showed 33 different pulsotypes.

Conclusion:

This study confirms that different isolates of MSSA and MRSA circulate in Ilam which differ in antimicrobial susceptibility, content of resistance, and virulence determinants.

[The possibilities for the rational pharmacotherapy of adenoiditis in the children]

The available literature data give evidence that viral infection is the main cause underlying the development of inflammatory nasopharyngeal pathology in the children. According to ICD-10, nether acute nor chronic adenoiditis should be considered as a self-consistent nosological entity. Acute adenoiditis is usually regarded as a form of acute nasopharyngitis (J02) or acute respiratory viral infection (J06.9) whereas chronic adenoiditis is commonly referred to as representing other chronic diseases of the tonsils and adenoids (J 35.8). The reactive changes in the nasopharyngeal tonsils begin to be manifested on days 3-5 after the onset of acute respiratory viral infection; thereafter, they persist and gradually disappear within the next 2-3 weeks. In the majority of the cases, acute adenoiditis is actually a physiological reaction of the nasopharyngeal tonsils as the organs of regional mucosal immunity to antigenic stimulation. There is no universally accepted opinion as regards the duration of the inflammatory process which would allow these pathological changes to be considered as turned into chronic ones. This condition is actually not a serious pathology provided it is not associated with the concomitant complications and produces no clinically significant effect on the child's quality of life. Under practical conditions, such children are most frequently treated with the use of irrigation therapy. Taking into account that otorhinolaryngologists all over the world do not consider chronic adenoiditis as an independent nosological entity but distinguish only hypertrophy of adenoid vegetations or chronic rhinosinusitis (in the presence of inflammatory changes in the nasopharynx), it appears correct to speak about chronic adenoiditis provided the clinical manifestations of the disease persist for more than 12 weeks. Based on the predominant etiological component, the viral, bacterial, and allergic forms of nasopharyngeal adenoiditis can be distinguished even though it is rather difficult to actually determine which etiological factor prevails in each concrete case. The aforedescribed situation poses a large number of questions pertaining to the choice of either systemic or topical antibacterial therapy.

Prevalence of Panton-Valentine leucocidin and phenotypic and genotypic characterization of biofilm formation among Staphylococcus aureus strains isolated from children with adenoid hypertrophy

Adenoids as a first line of host defense against respiratory microbes play an important role in majority of upper airway infectious and noninfectious illnesses. Bacterial pathogen can colonize on the adenoid tissue and probably act as a reservoir for them. To determine phenotypic and genotypic characterization of biofilm forming capacity of Staphylococcus aureus isolates from children with adenoid hypertrophy and prevalence of Panton-Valentine leukocidin (PVL) gene we collected 17 consecutive, clinically significant S. aureus isolates from children with adenoid hypertrophy undergoing adenoidectomy with one or more of the upper airway obstruction symptoms, nasal obstruction, mouth breathing, snoring, or sleep apnea. Biofilm formation was evaluated by colorimetric microtiter plate's assay. Gene encoding PVL and adhesion- or biofilm formation-encoding genes were targeted by polymerase chain reaction (PCR) assay. According to the results, all strains produced biofilm. Seven (41.2%) isolates produced strong biofilm whereas 7 (41.2%) isolates produced week and 3 (17.6%) isolates produced medium biofilm. Regarding the adhesion- or biofilm formation-encoding genes, 16 (94.1%) isolates were positive for the gene eno, 13(76.4%) for icaA, 13 (76.4%) for icaD, 10 (58.8%) for fib, 10 (58.8%) for fnbB, 4(23.5%) for can, and 1(5.8%) for fnbA. The high prevalence of genes encoding biofilms and adhesins and phenotypic ability to form a biofilm by S. aureus strains emphasizes the pathogenic character of strains isolated from children with adenoid hypertrophy.

Molecular Typing of Hospital-Acquired Staphylococcus aureus Isolated from Isfahan, Iran

Background. Staphylococcus aureus (S. aureus) is one of the most common pathogens that cause hospital- and community-acquired infections in the world. The use of molecular typing methods is essential for determining the origin of the strains, their clonal relations, and also in epidemiological investigations. The purpose of this study was to determine the prevalence of antibiotic resistant S. aureus isolates and using spa, agr, and SCCmec typing to determine the dominant types in Iran. Material and Method. Fifty isolates of S. aureus were collected from January to May 2010. S. aureus identification was performed by biochemical tests. Disk diffusion method was employed to assess the sensitivity of S. aureus strains to antibiotics and then genetic analysis of bacteria was performed using SCCmec, agr, and spa typing. Results. S. aureus resistance to tetracycline, cefoxitin, clindamycin, ciprofloxacin, gentamicin, Cot: cotrimoxazole, levofloxacin, rifampin, and vancomycin were found to be 36%, 18%, 12%, 12%, 22%, 6%, 6%, and 0%, respectively. The results of this study showed that 16% of the isolates were resistant to methicillin (MRSA) and the majority of isolates were SSC mec type IV. In addition spa and agr typing revealed agr typeI and spa type t7688 to be the most predominant. Conclusion. In this study, spa typing showed 100% reliability and the t7688 spa type had a frequency of 26% compared to the frequency of 0.0% in the Ridom SpaServer. The frequency of t304 spa type was higher than the global average.

Role of adenoid biofilm in chronic otitis media with effusion in children

To study the extent of surface adenoid biofilm and to evaluate its role in the pathogenesis of chronic otitis media with effusion (COME) in children. The study was carried out on 100 children between 3 and 14 years of age, who were divided into two groups. The first group (50 children) had otitis media with effusion associated with adenoid hypertrophy, whereas the second group (50 children) had adenoid hypertrophy without middle ear effusion. Adenoidectomy with ventilation tube insertion was done for group 1 cases, whereas, only Adenoidectomy was done for group 2 cases. Microbiological study, Scanning electron microscope and multiplex- PCR were done for suspected adenoid biofilms and specimens from middle ear effusion. Adenoids removed from children with COME had higher grade biofilm formation (74 %) than the second group (42 %). No correlation was found between adenoid size and biofilm formation. Culture of adenoid tissue in group 1 patients was positive in 52 % of cases compared to 96 % by PCR, while in group 2 culture of adenoid tissue was positive in 38 % compared to 48 % by PCR. Culture of middle ear fluid was positive in 32 % of cases only compared to 80 % by PCR. A positive correlation was found between results of bacterial biofilm visualized by SEM and bacteria detected and identified by PCR technique. On the other hand, no correlation was found between results of bacterial biofilm visualized by SEM and bacteria detected by culture. The size of the adenoid is not the main determinant factor in OME pathogenesis but the degree of bacterial colonization is much more important. Adenoids in COME may act as a reservoir of chronic infection rather than causing mechanical Eustachian obstruction. Higher grade biofilm formation was found in cases with middle ear effusion than those with adenoid hypertrophy only. These findings support the hypothesis that there would be an association between adenoidal biofilm formation and COME. This study focused on the value of PCR in detecting pathogens in the adenoid and middle ear specimens although the bacterial culture would be negative.

Molecular analysis of typical and atypical enteropathogenic Escherichia coli (EPEC) isolated from children with diarrhoea

Diarrhoea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. To investigate the incidence, antimicrobial resistance and genetic relationships of enteropathogenic Escherichia coli (EPEC) in children with diarrhoea, a total of 612 stool specimens were collected in Tehran, Iran, and cultured to isolate strains of EPEC. The disc diffusion method was used to determine the susceptibility of the isolates according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of eae, stx and bfp-A genes was determined by PCR. The genetic relationships between EPEC isolates were determined by pulsed-field gel electrophoresis (PFGE). Out of the 412 strains of E. coli obtained from 612 diarrhoeal stool specimens, 23 (5.6 %) were identified as EPEC, of which seven (30.4 %) were classified as typical strains of EPEC and 16 (69.6 %) were classified as atypical. Out of the 23 EPEC isolates, 69.5 % were resistant to ampicillin, 39.1 % were resistant to tetracycline and cotrimoxazole, 30.4 % were resistant to cefpodoxime, ceftazidime, ceftriaxone and aztreonam, and 26.1 % were resistant to imipenem. The isolates were classified into 21 pulsotypes by PFGE profiles. The present study shows that typical and atypical EPEC isolates displayed considerable heterogeneity in PFGE profiles and EPEC infections were only sporadic in Tehran. Overall 69 % of isolates were resistant to at least one of the antibiotics tested.