Evaluation of Broth Disk Elution Method to Determine Colistin Resistance in Klebsiella pneumoniae and Escherichia coli Strains.

BACKGROUND: The reference broth microdilution (rBMD) method for the determination of colistin resistance is very laborious and time consuming, and many manual errors can occur. There are also limitations in detection of colistin heteroresistance. Therefore, alternative methods with satisfactory performance are required for routine laboratory work. In our study, the colistin broth disk elution (CBDE) method recommended by the Clinical and Laboratory Standards Institute (CLSI) for the detection of colistin resistance in routine applications was compared with rBMD. The compatibility and error rates of the method were evaluated and its usability in routine laboratory studies was examined. METHODS: Eighty-nine multidrug resistant Klebsiella pneumoniae and five Echerichia coli strains isolated from various clinical specimens were included in the study. Identification of strains and antibiotic susceptibility tests were performed with MALDI-TOF MS (bioMerieux, France) and Vitek-2 (bioMerieux) system. Minimum inhibitory concentration (MIC) was studied in 0.125 - 128 mg/L dilution range by using polystyrene microplate and colistin sulfate salt according to ISO-standard (20776-1) recommendations for the reference BMD test. The CBDE method was performed according to the CLSI recommendations. Isolates with MIC ≤ 2 mg/L were considered susceptible, while isolates with MIC > 2 mg/L were considered resistant according to EUCAST recommendations. The performance of the CBDE method was evaluated according to ISO criteria (Categorical agreement > 90%; major error and very major error rates < 3%). RESULTS: Categorical agreement for all 58 and 36 isolates found to be resistant and susceptible, respectively, by rBMD was found to be 100% with CBDE test. Since < 1 and > 4 µg/mL values could not be determined with the CBDE method, essential agreement (EA) could not be calculated. No major or very major errors were detected. CONCLUSIONS: Our results showed that the performance of the CBDE test is good when compared to the rBMD method. According to our data, we believe that the CBDE method can be used in routine laboratories for the detection of colistin resistance.

Prevalence of carbapenemases in Enterobacterales from urine specimens in an university hospital in Istanbul, Turkey.

We aimed to investigate the prevalence of carbapenemases in Enterobacterales strains isolated from urine specimens between July 2019 and July 2020.CIM and modified CIM tests were applied as well as detection of blaOXA-48, blaNDM, blaVIM, blaKPC and blaIMP genes was performed by multiplex PCR.One hundred fifty of 3,242 Enterobacterales strains were found to be carbapenem resistant and 46 were included in the study. Forty five (98%) of the 46 strains included in the study were Klebsiella spp. and one (2%) of them was Escherichia coli. Susceptibility to ceftazidime-avibactam, amikacin and gentamicin was 97%, 11% and 9%, respectively. Forty three (94%) isolates were found positive at 2 and 4 h with CIM test. Forty four (97%) strains were found positive at 4 h and 43 (94%) strains were found positive at 2 h with modified CIM test.While blaOXA-48, blaNDM and blaOXA-48 with blaNDM association were found in Klebsiella spp. isolates in 55%, 27% and 11%, respectively, blaVIM, blaKPC, blaIMP were not found. Only blaOXA-48 and blaNDM-1 were detected in the E. coli strain.None of the investigated genes were detected in three Klebsiella strains but with whole genome analysis the combination of blaOXA-534, blaCMY-99 and blaKPC-3 was found in the first strain, blaOXA-370 in the second strain and no resistance gene was found in the third strain.Ceftazidime-avibactam was found to be active against 97% of strains, and the most common resistance genes were blaOXA-48 and blaNDM-1. Previously undetected resistance genes have been identified in our country.

Detection of colistin resistance among multidrug-resistant Klebsiella pneumoniae and Escherichia coli clinical isolates in Turkey.

In this study investigation of plasmid-mediated mcr 1-5 resistance genes was performed among multidrug-resistant (MDR) colistin sensitive and resistant Klebsiella pneumoniae and Escherichia coli strains isolated in our laboratory. We aimed to evaluate automated system (Vitek-2), broth microdilution (BMD) reference method and chromogenic media performance. Totally 94 MDR K. pneumoniae and six E. coli isolates were included in the study. CHROMID® Colistin R agar (COLR) (bioMerieux, France) was used to determine the colistin resistance by chromogenic method. Standard PCR amplification was performed using specific primers to screen the plasmid-mediated mcr 1-5 genes. Sixty-one isolates were resistant to colistin and 39 were susceptible with reference BMD. The essential and categorical agreement of Vitek-2 was determined as 100 and 99%. The sensitivity of COLR medium was 100%, the specificity was 97.5%. In our study mcr-1 was detected in eight isolates, while other mcr genes were not detected. Due to the high sensitivity and specificity of the COLR medium, it can be used in routine diagnostics for the detection of colistin resistance. In our study we detected 8% prevalence of mcr-1 among MDR strains however, two mcr-1 positive isolates were found sensitive to colistin by BMD.

OXA-type Carbapenemases and Susceptibility of Colistin and Tigecycline Among Carbapenem-Resistant Acinetobacter Baumannii Isolates from Patients with Bacteremia in Turkey.

BACKGROUND: Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as one of the most troublesome pathogens in healthcare settings worldwide. The present study was conducted to analyze the genes encoding resistance to carbapenems and to determine in vitro activity of colistin and tigecycline against CRAB isolates from blood culture of hospitalized patients at Istanbul University Cerrahpasa Medical School hospital. METHODS: Between January 2012 and June 2014, a total of 72 CRAB isolates were isolated by conventional methods from blood cultures of patients with bacteremia who were hospitalized in intensive care units and in various departments of the hospital. The isolates were confirmed using a Phoenix automated system. Antibiotic susceptibilities were determined by disk diffusion method and Etest. Molecular detection of resistance genes were screened by multiplex real time polymerase chain reaction (qPCR) and PCR parameters. RESULTS: CRAB isolates were highly resistant to tetracycline (86.1%), trimethoprim/sulfamethoxazole (84.7%), ceftazidime (83.3%), cefepime (81.9%), ciprofloxacin (81.9%), amikacin (75.0%), piperacillin/tazobactam (75.0%), cefotaxime (72.2%), and gentamicin (69.4%). Tigecycline and colistin resistance were not detected. MIC50 and MIC90 of tigecycline (MIC ranges 0.016-1 µg/mL) and colistin (MIC ranges 0.125-1.5 µg/mL) were found to be 0.5 µg/mL and 1 µg/mL, respectively. All isolates were positive for OXA-51 that shows molecular identification of A. baumannii. Fifty-one (70.8%) and 2 (2.8%) of these isolates were positive for OXA-23 and OXA-58 genes, re- spectively. CONCLUSIONS: This study indicated the most of the CRAB isolates in our hospital carry the OXA-23 gene. Colistin and tigecycline resistance were not detected. However, significant effort must be done to prevent the spread of OXA-23-producing CRAB-isolates and continuous monitoring of drug resistance is necessary in clinical settings.

[Antibiotic susceptibility rates and beta-lactam resistance mechanisms of Pseudomonas aeruginosa strains]. / Pseudomonas aeruginosa Suslarinda Antibiyotik Duyarlilik Oranlari ve Beta-Laktam Direnç Mekanizmalarinin Tiplendirilmesi.

Pseudomonas aeruginosa is a well-known cause of severe and potentially life-threatening infections including bacteremia, skin and wound infections, pulmonary disease, especially among individuals with cycstic fibrosis, nosocomial urinary tract infections, endocarditis and meningitis. The mechanism of resistance to broad-spectrum beta-lactams in P.aeruginosa are overexpression of cephalosporinases and/or class A, B and D beta-lactamases. Recently PER-1 type beta-lactamase has been reported from Turkey, France, Italy, Romania, Hungary, Belgium, Russia, South Korea and India. OXA beta-lactamases have increasingly been reported in clinical strains of P.aeruginosa from various geographical origins. This study was aimed to investigate the antibiotic susceptibility of various P.aeruginosa clinical strains and to define the beta-lactamase enzymes leading to resistance. In this study, a total of 100 P.aeruginosa strains isolated from various clinical specimens (37 urine, 21 blood, 10 sputum, 5 bronchoalveolar lavage, 5 abscess, 5 wound swabs, 4 endotracheal aspirate, 3 throat swabs, 2 catheter tips, one of each pleural and peritoneal fluid) were included. According to Clinical and Laboratory Standards Institute (CLSI) recommendations, susceptibilities of isolates to various antibiotics were investigated by disk diffusion and agar dilution method, and beta-lactamase enzymes were detected by isoelectric focusing (IEF) method. PSE, PER-1, OXA-10-like beta-lactamase genes and MEX-R genes of isolates were investigated by polymerase chain reaction (PCR). According to MIC90 values, the most effective antibiotics were found to be imipenem (8 µg/ml). The MIC90 values of amikacin, ciprofloxacin, cefepime, cefpirome, piperacillin + tazobactam, piperacillin, ceftazidime, ticarcilin, aztreonam and ticarcilin + clavulanic acid were 32, 64, 64, 64, 128/4, 512, 512, 512, 512 and 512/2 µg/ml, respectively. Seven of the isolates were found to be ESBL positive by double-disk synergy method. It was detected that 10% of the isolates were imipenem-susceptible and 9% were intermediate susceptible. Phenotypical investigation of metallo-beta-lactamase enzyme in these strains by MBL E-test method did not reveal a positive result. PER-1 and OXA-10 like beta-lactamases were detected each in 11% of the isolates, and co-presence of PER-like and OXA-10 like enzymes were shown in 4% of the isolates. PSE gene was not found in any of the strains. The MEXR gene was identified in 52% of the isolates. Antibiotic resistance mechanisms in P.aeruginosa strains seems to be complex. Determination of the resistance mechanisms and antibiotic susceptibility rates in P.aeruginosa will guide the proper antimicrobial therapy, reducing the emergence of resistant strains.

Performance of the Rapidec®Carba NP assay for the detection of different carbapenemases in Klebsiella pneumoniae and Escherichia coli strains.

PURPOSE: The spread of infections caused by Enterobacterales strains resistant to carbapenems is a global public health problem, and early detection of carbapenemases is very important to prevent their spread. The rapid detection of carbapenemase production with the new commercial assay Rapidec® Carba NP test is based on the biochemical detection of imipenem hydrolysis. Our study aims to evaluate the performance of the Rapidec® Carba NP test in OXA-48 positive isolates highly prevalent in our country and also in isolates with more than one carbapenemase gene that have an increased prevalence and to examine whether it can be used for confirmation of carbapenemase positivity in the routine laboratory. METHODS: A total of 97 strains of 94 carbapenem-resistant Klebsiella pneumoniae and three carbapenem-resistant Escherichia coli isolated from various clinical specimens were included in the study. The results of the Rapidec® Carba NP assay were compared with those obtained by the multiplex PCR test. RESULTS: The sensitivity of the Rapidec® Carba NP test was 97.8% for all carbapenemase-positive isolates. Of 90 PCR positive isolates, one OXA-48 and one OXA-48 â€‹+ â€‹NDM positive isolates were negative with Rapidec® Carba NP test. CONCLUSIONS: The positive results detected by the Rapidec® Carba NP test make an important contribution to the early detection of carbapenemase production and infection control practices. Since two carbapenemase positive isolates were found to be negative with the Rapidec® Carba NP test in our study, it was concluded that negative results of carbapenem-resistant isolates obtained with this assay should be confirmed with an additional carbapenemase detection method to exclude false-negative results.

The role of typical and atypical pathogens in acute exacerbations of chronic obstructive pulmonary disease.

OBJECTIVES: The exact role of Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila in the development of chronic obstructive pulmonary disease exacerbations remains to be elucidated. This study was conducted to identify nonspecific and atypical pathogens associated with acute exacerbations of COPD. MATERIALS AND METHODS: Between February 2013 and February 2015, 107 patients were analyzed. Sixty-nine comprised the inpatient and 38 comprised the outpatient treatment group. RESULTS: When nonspecific culture results were taken into consideration only a causative organism could be detected in 46.7% of the patients. The detection rate increased to 85.1% with the additional use of polymerase chain reaction (PCR), direct fluorescent antibody (DFA) test, and culture methods. More than one causative agent was responsible for COPD exacerbation in 53.3% of patients: two agents in 37.3%, three agents in 15%, and four agents in 0.9%. H. influenzae was detected in 63 (58.9%) patients, S. pneumoniae in 57 (53.2%), P. aeruginosa in 15 (14.0%), and L. pneumophila in 11 (10%). L. pneumophila was the more commonly isolated agent in the inpatient group (P = 0.002). Patients receiving continuous oxygen therapy and noninvasive mechanical ventilation were more likely to have an exacerbation associated with P. aeruginosa (P = 0.008 and P = 0.009, respectively). CONCLUSION: The additional use of DFA for Legionella and multiplex PCR in combination with nonspecific microbiological culturing methods greatly improves the ability to identify infectious agents in acute exacerbations of COPD. There should be a high index of suspicion for P.aeruginosa as a causative organism, particularly in subjects receiving continuous oxygen therapy and/or using NIV and L. pneumophila should certainly be taken into consideration in severe COPD exacerbations.

Comparison of in vitro activities of tigecycline with other antimicrobial agents against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in two university hospitals in Istanbul, Turkey.

BACKGROUND: We compared the in vitro activities of tigecycline with those of other agents against 97 Streptococcus pneumoniae, 140 Haemophilus influenzae and 54 Moraxella catarrhalis strains isolated in two large university hospitals in Istanbul. METHODS: For analysis, the agar dilution method was used. RESULTS: For S. pneumoniae isolates, 32% were not susceptible to penicillin (28.9% intermediate and 3.1% resistant). Cefotaxime, telithromycin, moxifloxacin and linezolid were fully active. Tigecycline had a 90% minimum inhibitory concentration (MIC(90)) of 0.12 microg/ml. For H. influenzae, 8.57% were not susceptible to ampicillin, among which 8 possessed beta-lactamase (5.7%). Four (2.87%) H. influenzae isolates with beta-lactamase-negative and ampicillin-resistant phenotype were found. All isolates were susceptible to ceftriaxone, azithromycin, ciprofloxacin, levofloxacin and moxifloxacin. MIC(90) for tigecycline was 0.5 microg/ml. Of 54 M. catarrhalis isolates, 88.9% possessed beta-lactamase. Tigecycline and fluoroquinolones were highly active (MIC(90) < or =0.12 microg/ml). CONCLUSIONS: Linezolid, telithromycin, newer fluoroquinolones and tigecycline all have excellent in vitro activities against the 3 respiratory pathogens.

In Vitro Investigation of the Antibacterial Activity of Nigella sativa Oil on Some of the Most Commonly Isolated Bacteria in Otitis Media and Externa.

OBJECTIVE: This study aimed to evaluate the antibacterial efficacy of Nigella sativa (NS) seed oil against the most frequently isolated infectious bacteria of the middle and external ear. MATERIALS AND METHODS: The in vitro antibacterial activity of NS oil was evaluated against 34 clinical isolates of Streptococcus pneumoniae, 32 clinical isolates of Moraxella catarrhalis, 32 clinical isolates of Haemophilus influenzae, and 32 clinical isolates of Pseudomonas aeruginosa. Staphylococcus aureus, Escherichia coli, and P. aeruginosa were also evaluated for their sensitivity to the NS oil. The minimum inhibitory concentration (MIC) of the NS oil was determined via a broth dilution technique. Serial solutions were prepared in a Mueller Hinton-F broth to achieve an ultimate concentration of NS oil within the microplate wells ranging from 256 µg/mL to 0.25 µg/mL. The growth control wells and medium were used for each bacterial strain, and the microplates were incubated at 35°C for 24 h. Those wells having no visible growth and the lowest concentration of NS oil were accepted as showing the MIC. RESULTS: In this study, a comparison was made between NS oil and the various antibiotics known to be effective against the bacterial strains mentioned above. The NS was shown to have bactericidal activity against H. influenzae, M. catarrhalis, and S. pneumoniae. However, the NS was not found to be effective against P. aeruginosa at any concentration. CONCLUSION: The results of this laboratory-based study support the use of NS oil as an alternative treatment for ear infections. However, it is necessary to conduct clinical studies to evaluate the antibacterial efficacy of NS oil on patients with ear infections.

Dissemination of CTX-M-15 beta-lactamase genes carried on Inc FI and FII plasmids among clinical isolates of Escherichia coli in a university hospital in Istanbul, Turkey.

The CTX-M-1 group was found in 86.8% of the Escherichia coli isolates from Istanbul. A subset study revealed all isolates carrying bla(CTX-M-15) genes flanked by the insertion element ISEcp1. Plasmid typing of transconjugates carrying bla(CTX-M-15) showed that most isolates belonged to the Inc/rep FII group but that one isolate also belonged to the FI group.

The influence of glucose added urine on the in vitro antimicrobial activity of various antibiotics.

BACKGROUND & OBJECTIVE: Factors associated with the medium, including calcium and magnesium ion concentration and pH have been shown to affect the results of susceptibility testing but very little is known about glycosuria and the effect of glucose on the antimicrobial effect of antibiotics. In this study we assessed the influence of glucose added urine on the in vitro activities of various antibiotics by the microbroth dilution method. METHODS: Sixteen Escherichia coli isolates from patients with urinary infections were used in this study. Nine antibiotics were tested for their antimicrobial activity. Minimum inhibitory concentrations (MICs) were performed by the microbroth dilution method parallel in Mueller Hinton broth and glucose added urine. RESULTS: MICs of nearly all antibiotics were higher in glucose added urine than MICs in broth. MIC(90) against ampicillin was 32-fold higher in glucose added urine than MIC(90) in broth. MIC(90)s against ampicillin-sulbactam, cephalothin, cefuroxime, ceftriaxone and ciprofloxacin in glucose added urine were significantly (P<0.05) higher than MIC(90) in broth. Equal MIC(90) in glucose added urine and broth were obtained for amikacin, sulphamethoxazole and trimethoprime. INTERPRETATION & CONCLUSION: Our findings demonstrated that MICs of antibiotics are influenced by the glucose added urine.

Pneumococcal Nasopharyngeal Carriage in Young Healthy Children After Pneumococcal Conjugate Vaccine in Turkey.

AIMS: To determine the prevalence of nasopharyngeal carriage of Streptococcus pneumoniae in healthy children aged 0-6 years who were vaccinated with pneumococcal conjugate vaccine. METHODS: This cross-sectional study was conducted on 150 healthy Turkish children between 1 month and 6 years of age. Serotyping was performed and risk factors of carriage were evaluated. RESULTS: The overall carriage rate was 14%. Vaccine type serotypes were determined in 17 (12.6%) children who received full-dose PCV13 vaccine. The highest carriage rate was observed among children younger than 24 months (76.2%). In multivariate analysis, respiratory infection in recent months, age, attendance at a day-care center and antibiotic usage were not statistically significant risk factors for carriage. Overall, S. pneumoniae strains were considered as penicillin susceptible and antimicrobial resistance was limited. CONCLUSION: We observed a low rate of pneumococcal carriage in children after PCV13 implementation compared with that of children receiving PCV7. Although it was reduced, vaccine serotype colonization in PCV13-vaccinated children remains persistent.

[Detection of CTX-M-15 type extended spectrum beta-lactamase in an Escherichia coli strain isolated from the urine sample of a hospitalized patient]. / Hastanede yatan bir hastanin idrar örneginden izole edilen Escherichia coli susunda CTX-M-15 tipi genislemis spektrumlu beta-laktamazin tanimlanmasi.

In this study, a CTX-M type extended spectrum beta-lactamase (ESBL) enzyme has been detected in a multiresistant Escherichia coli strain which was isolated from the urine sample of a hospitalized patient. Minimum inhibitor concentrations (MIC) of the tested antibiotics were determined by the agar dilution technique according to the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) guidelines. The isolate was found to be sensitive to imipinem, moderately susceptible to chloramphenicol and resistant to ceftazidime, cefotaxime, aztreonam, ciprofloxacin, tobramycin, tetracycline and trimethoprim/sulphamethoxazole. Ceftazidime/ceftazidime-clavulanic acid and cefotaxime/cefotaxime-clavulanic acid rates were found as >8 and the results were accepted as positive for an ESBL. The MIC of cefotaxime (256 microg/ml) was found four fold higher than that of ceftazidime (64 microg/ml) and the production of a CTX-M- type ESBL was investigated in the strain. Cefotaxime resistance, together with tobramycin and tetracycline resistance, was transferred to the recipient strain by conjugation. The pl's of the culture extracts of the isolate were found as 5.4, 7.5 and 9.1 by isoelectric focusing (IEF) method, but cefotaxime was hydrolysed only by the beta-lactamase focusing at a pl of 9.1 in the following bioassay. The bla-gene was amplified with the CTX-M group specific primers and sequencing of the polymerase chain reaction (PCR) product proved the enzyme to be CTX-M-15. This isolate was also found to harbor TEM- and SHV-type and OXA-10-like ESBLs, by IEF and PCR.

Phenotypes and genotypes of macrolide-resistant streptococcus pneumoniae.

BACKGROUND: Macrolide resistance in Streptococcus pneumoniae (S. pneumoniae) is a worldwide problem. AIMS: The aim of this work was to analyze the phenotypes, genotypes, and clonal relatedness among macrolide-resistant S. pneumoniae strains isolated from various clinical specimens in our hospital. STUDY DESIGN: Cross-sectional study. METHODS: 80 non-duplicate S. pneumoniae strains were analyzed by polymerase chain reaction for both the erm (B) and mef (A) genes. RESULTS: Macrolide resistance was observed in 22.5% (18 strains) of strains. Two (11.2%) isolates possessed mef (A), eight possessed erm (B) (44.4%) and eight strains (44.4%) were positive for both erm (B) and mef (A) genes. Although BOX-PCR of 18 macrolide-resistant strains revealed 11 band patterns, they clustered as seven clones with a genetic distance >10% to each other. Eight isolates possessed both erm (B) and mef (A) genes and belonged to a single clone (44.44% of all macrolide-resistant strains). CONCLUSION: Increased positivity rates for both resistance genes have also been reported from other hospitals in Turkey, but this is the first study from Turkey showing the clonal dissemination of both resistance genes.

Use of INNO-LIPA assay for rapid identification of mycobacteria.

Using 106 clinical isolates of mycobacteria, we showed that INNO-LIPA Mycobacteria assay is an excellent tool to rapidly identify the most frequently isolated nontuberculous mycobacteria, in one procedure. It may be used as an additional technique to AccuProbe assay, which remains the fastest and the cheapest tool for a rapid and accurate identification of the M. tuberculosis complex.

In vitro activity of telithromycin compared with macrolides and fluoroquinolones against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.

The in vitro activity of telithromycin was compared with erythromycin A, azithromycin, clarithromycin, moxifloxacin, gemifloxacin, levofloxacin, ciprofloxacin, penicillin G, ampicillin, cefuroxime and ceftriaxone against 336 consecutive strains (83 Streptococcus pneumoniae, 168 Haemophilus influenzae and 85 Moraxella catarrhalis) isolated from patients with community-acquired respiratory tract infections. Telithromycin (MIC(90), 0.008 mg/l) was the most active drug against S. pneumoniae. Telithromycin was also highly active against M. catarrhalis (MIC(90), 0.06 mg/l), but less active against H. influenzae (MIC(90), 4 mg/l).

Moxifloxacin activity against clinical isolates compared with the activity of ciprofloxacin.

The activity of moxifloxacin, a new 8-methoxyquinolone, was compared in vitro with the activity of ciprofloxacin against clinical strains isolated from various sites of infection. The mode MIC values of moxifloxacin were superior to those of ciprofloxacin against Streptococcus pneumoniae, methicillin-susceptible and -resistant Staphylococcus aureus, Enterococcus spp., Escherichia coli and Acinetobacter spp., while ciprofloxacin was more active against Klebsiella pneumoniae and Pseudomonas spp. Both antibiotics had similar activity against Haemophilus influenzae, Moraxella catarrhalis and Enterobacter spp.

Effect of nasal mometasone furoate on the nasal and nasopharyngeal flora.

OBJECTIVE: Mometasone furoate (MF) is one of the commonly used topical steroids, particularly for patients with allergic rhinitis. However, its effect on the colonization of bacteria that may cause superinfections by suppressing the local immunity is not known. Thus, we investigated the effect of MF use on the nasal and nasopharyngeal microbial flora. MATERIALS AND METHODS: Swab samples were taken from 35 patients who required MF monotherapy, just before and after one month of the treatment. Samples were maintained in Stuart's medium. Each swab was transferred to 1ml of a sterile saline solution, then into the standard agar. After incubation under 5% carbon dioxide at 37°C, colony number was detected per ml. RESULTS: Colony counts of nasal or nasopharyngeal microbial flora did not show any statistically significant alteration with one month use of MF. However, an increase in potential pathogens as well as normal flora bacteria was determined in five of the patients and six patients acquired new nasopharyngeal potential pathogens, mostly Moraxella catarrhalis, Pseudomonas aeruginosa and Staphylococcus aureus, following the use of MF. CONCLUSION: The use of MF for one month did not statistically significantly change the nasal and nasopharyngeal flora. This study indicates that MF could be increase the colonization of the potential pathogens in some of the patients at the subclinical level particularly in the nasopharyngeal area.

Oropharyngeal flora changes after tonsillectomy.

OBJECTIVE: We aimed to investigate the effect of tonsillectomy on oropharyngeal flora in children who underwent tonsillectomy for chronic recurrent tonsillitis. STUDY DESIGN AND SETTING: A prospective study was performed comprising patients with chronic recurrent tonsillitis who underwent tonsillectomy at the Department of Otolaryngology, Cerrahpasa Medical School. Incisional core biopsies of excised tonsils were also performed. Swabs and core biopsy specimens were transferred and maintained in Stuart's medium and sent to the Department of Microbiology and Clinical Microbiology at Cerrahpasa Medical School for microbiologic evaluation. SUBJECTS AND METHODS: Oropharyngeal swabs and tonsillar core biopsy specimens from 31 patients operated on for recurrent tonsillitis were cultured. Follow-up oropharyngeal swabs were cultured one month after tonsillectomy. RESULTS: There was no significant difference between the preoperative and postoperative isolation rate of the potentially pathogenic bacteria. Normal aerobic flora did not change significantly. However, the isolation rate of the Neisseria species dropped (P = 0.097) but did not reach statistical significance. Among anaerobes, Bacteroides fragilis, one of the major anaerobic bacteria, dropped significantly (P = 0.007). The Propionibacterium acnes isolation rate increased significantly (P = 0.009). CONCLUSION: Oropharyngeal anaerobic bacterial flora decreases after tonsillectomy in recurrent tonsillitis patients. The isolation rate for bacteria of the normal flora and potentially pathogenic bacteria does not change. Tonsils with recurrent infections may become a nidus for anaerobic bacteria. In patients with chronic recurrent tonsillitis, tonsillectomy may help change anaerobic bacterial oropharyngeal flora to the normal flora found in healthy individuals.

Implant-related infection model in rat spine.

OBJECTIVE: The rate of postoperative infections is approximately 1% in spine surgery. However, when metal implants are used, postoperative infection rates significantly increase and were reported between 2.1 and 8.5%. This study aim to set up an infection model in the rat spine with a metal implant. MATERIALS AND METHODS: Forty white male Sprague Dawley rats were randomly divided in four groups. In all rats, under operation microscope, a 3 mm titanium microscrew was implanted in the thoracolumbar area (T10-L1) after laminar decortication. In Group I (control group), sterile isotonic solution and in other three groups, different concentrations of Staphylococcus aureus [Group II: (10(2)), Group III: (10(3)), Group IV: (10(6))] were squirted on the decorticated lamina site. All animals were sacrificed after 2 weeks, and then blood cultures and cultures from fascia, muscle and bone were obtained. Bacterial number in each tissue was measured as colony-forming unit per gram tissue. Titanium microscrews were placed in 0.5 ml tryptic soy broth and vortexed than plated on trypticase soy agar to determine bacterial growth. Two animals from each group were subjected to histological examination. RESULTS: Blood cultures obtained by intra-atrial puncture after 2 weeks were negative in all groups indicating no systemical infection developed. Bacterial cultures were negative in all specimens of Group I (control group). A significant osseous infection was confirmed in Groups II, III and IV. Comparison of bacterial counts in bone cultures showed no significant difference between Group III (10(3) CFU/10 microl) and Group IV (10(6) CFU/10 microl) (P > 0.05), while both groups had significantly higher counts than Group II (10(2) CFU/10 microl) (P > 0.05). Microscopic findings of supurrative inflammation were present only in Group IV (10(6) CFU/10 microl). CONCLUSIONS: This study shows that inoculation of S. aureus in 10(6) CFU/10 microl concentration at the decorticated lamina after implantation of a titanium screw in rat spine is a reproducible model for spinal infection and can be used for the animal model of prophylaxis and treatment and of postoperative infection.