Slide Latex Agglutination Test Research Articles

Relation between Epstein-Barr virus (EBV) with some biochemical variables in high-risk aborted women in Mosul city, Iraq

Epstein-Barr Virus (EBV), or Kissing Virus, is a member of the Herpes virus that can be a contributory factor for compromised pregnant, high-risk aborted women worldwide. The present study aimed to detect high-risk EBV by the Monospot test for pregnant, high-risk aborted women, to detect immunoglobulin IgM and IgG for EBV using Enzyme-linked immunosorbent assay (ELISA) technique, to distinguish the infections as acute, chronic, or reactivated, and to determination of Enzymes as Aspartate Transaminase (AST), Alkaline phosphatase (ALP), and Alanine Transaminase (ALT).A cohort of 91 serum samples were collected from high-risk aborted women (ages 15-45 years) who attended Al-Medina Private Laboratory from February to December 2022.Sera were tested for heterophile antibodies(HA) associated with Infectious Mononucleosis (IM) caused by EBV by Latex Agglutination slide test (IM Quick test) and were tested for IgM and IgG antibodies against EBV-CA in serum using the ELISA kit.Sera from the patients and healthy controls were analyzed for Glutamate-Pyruvate Transaminase (GPT), Glutamic Oxaloacetic Transaminase (GOT), Lactate Dehydrogenase (LDH), and Alkaline phosphatase. Compared to healthy controls, the data showed that the late phase with loss and reactivated infection was responsible for 25% of cases and that the acute and late infection cases had a high of 64%. There were significant differences in the level of these hormones;aborted women showed increased levels of serum ALP (70.83) while having a reverse effect with serum ALT (11.7) and AST (25.43). EBV activation was higher in the aborted women. The study would help to determine the role of EBV in the pathogenesis of abortion.

Investigation of methicillin-resistant Staphylococcus aureus, methicillin-susceptible Staphylococcus aureus, and Staphylococcus argenteus from wild long-tailed macaques (Macaca fascicularis) at Kosumpee Forest Park, Maha Sarakham, Thailand.

In the past, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infections in both humans and animals has increased across Thailand. Staphylococcus argenteus has been associated with infections among humans, exotic pets, and livestock. Both species have been identified in non-human primate species from geographically diverse locations but not from non-human primates in Thailand. This study aimed to determine the presence of MRSA/methicillin-susceptible S. aureus (MSSA) and S. argenteus isolates collected from buccal swab samples in Macaca fascicularis at Kosumpee Forest Park (KFP), Maha Sarakham, Northeast Thailand. Aseptic buccal swab samples were collected from 30 free-ranging macaques in November 2018. All isolates were tested using multiple biochemical tests and S. aureus latex slide agglutination test. Presumptive S. aureus isolates were tested for the presence of the mecA gene using polymerase chain reaction (PCR) assays. The isolates were phenotypically determined to be resistant to a β-lactam antibiotic using the disk diffusion method with a 30 mg cefoxitin disk. The isolates were analyzed by PCR for the non-ribosomal peptide synthetase (NRPS) gene to distinguish S. argenteus from S. aureus. Fifteen macaques (50%) were colonized with S. aureus and 21 isolates were characterized. Three of the macaques carried both the MRSA and MSSA isolate. One animal carried both MRSA and S. argenteus isolate, and one animal carried only S. argenteus. The NRPS gene analysis confirmed that 2 isolates (9.52%) were S. argenteus and 19 isolates (90.48%) were S. aureus [five MSSA and 14 MRSA]. This study is the first to identify MRSA/MSSA and S. argenteus in wild free-ranging M. fascicularis from Thailand at the KFP in Maha Sarakham. This study is also the first report on the occurrence of S. argenteus carriage in M. fascicularis from Thailand.

RELATIONSHIP OF D-DIMERS WITH THE DURATION OF CEREBRAL VENOUS SINUS THROMBOSIS (CVST): A DESCRIPTIVE STUDY IN TERTIARY HEALTH CARE HOSPITAL OF DISTRICT PESHAWAR PAKISTAN.

Purpose CVST is a serious condition with a recent incidence of 13 million persons per year. (1) It has a highly variable presentation and may manifest itself with no recognizable risk factor, Magnetic resonance venography (MRV) is the investigation of choice for its diagnosis. However, since MRV is not readily available and is costly, this study tried to find the relationship between the levels of D-dimers as marker and duration of CVST. D-dimers are degraded fibrin products which are found to be raised in pulmonary embolism and deep venous thrombosis.
 Methods: Total 49 patients (male to female ratio 1:6) mean age 36.37 13years) with MRV proven CVST were included in the study. This descriptive cross-sectional study was conducted from January 2015-April 2017, on 49 confirmed patients of CVST, in Lady Reading Hospital. In patients suspected of CVST, magnetic resonance imaging of the brain with MRV was performed without delay on a 1.5 tesla MR scanner using T1, T2, flair, and diffusion weighted imaging sequences with a two-dimensional time of flight MRV. D-dimers were estimated by a rapid latex agglutination slide test technique using monoclonal antibodies. Data was analyzed using SPSS version 19. Frequencies, mean were calculated for quantitative data while Chi-square test was used for qualitative data. Sensitivity and specificity were calculated.
 Result: The duration of symptoms was 3-60 days (mean 22 days). The mean value of D-dimers levels recorded in micrograms were recorded as 1456
 Conclusion: D-dimers levels were high in acute and subacute stage of CVST. However, there were cases in our study who despite having acute and subacute stage of CVST had normal D-dimers levels for unknown reasons.

Does the Application of a Semiocclusive Dressing Alter the Microflora of Healthy Intact Skin on the Foot?

The skin on human feet presents unique environments for the proliferation of potentially pathogenic commensals. This study examined microflora changes on healthy intact skin under a semiocclusive dressing on the medial longitudinal arch of the foot to determine changes in growth, distribution, and frequency of microflora under the dressing. Nine human participants wore a low-adherent, absorbent, semiocclusive dressing on the medial longitudinal arch of the left foot for 2 weeks. An identical location on the right foot was swabbed and used as a control. Each foot was swabbed at baseline, week 1, and week 2. The swabs were cultured for 48 hours. Visual identification, Gram staining, DNase test agar, and a latex slide agglutination test were used to identify genera and species. Microflora growth was categorized as scant (0-10 colony-forming units [CFU]), light (11-50 CFU), moderate (51-100 CFU), or heavy (>100 CFU). Scant and light growth decreased and moderate and heavy growth increased under the dressing compared with the control. Seven different genera of bacteria were identified. Coagulase-negative Staphylococcus spp appeared most frequently, followed by Corynebacterium spp. Changes in microflora distribution, frequency, and growth were found under the dressing, supporting historical studies. Microflora changes were identified as an increase in bioburden and reduction in diversity. The application of similar methods, using more sophisticated identification and analysis techniques and a variety of dressings, could lead to a better understanding of bacterial and fungal growth under dressings, informing better dressing selection to assist the healing process of wounds and prevent infection.

Effects of gamma-irradiation on antibiotic resistance and diagnostic molecular markers of methicillin-resistant Staphylococcus aureus in Egyptian cancer patients

:Purpose: This in-vitro study aimed to assess in 120 [40 community-acquired (CA-MRSA) & 80 hospital-acquired (HA-MRSA)] isolates from cancer patients whether the transmissible staphylococcal cassette chromosome mec (SCCmec) typing, and the Panton–Valentine leukocidin (PVL) virulence genes detection could be employed as tools for molecular diagnostic purposes to distinguish both methicillin-resistant Staphylococcus aureus (MRSA) categories in radiotherapy treated cancer patients.Materials and methods: SCCmec typing was determined by the combination of the type of the cassette chromosome recombinase genes (ccr) gene complex and the class of the methicillin resistance (mec) gene complex. Besides, a rapid slide latex agglutination test (LAT) and antibiotic resistance spectrum determination before and after irradiation were performed.Results: In the strict sense, with the effect of irradiation; the presence of SCCmec subtypes IVa (22.5% vs. 10.0%), b (47.5% vs. 25.0%), & d (7.5 vs. 2.5%) or type V (15.0% vs. 7.5%) genetic elements and PVL genes (p < .001) were not proved as a signature for CA-MRSA. While, the larger SCCmec types II, and III elements were not detected in 14, and 19 from the 38, and 36 typed HA-MRSA isolates (p < .001), respectively. Remarkable effects on class A & class B mec gene complex and type2, type 3 & type 5 ccr gene complex and an increase in agglutination reaction strength in response to gamma irradiation external stimulus were observed.Conclusions: Different heterogeneous genetic composition with upregulation mecA gene expression was detected after irradiation in the HA- MRSA studied population. CA-MRSA showed remarkable ability to acquire multi-antibiotic resistance after irradiation and propose a novel paradigm for future chemotherapy against the multi-resistant pathogens whose proliferation especially among immunocompromised cancer patients is on the increase.

Analysis of Serum Il-6 and CRP Levels among Autoimmune and Non-Autoimmune Hypothyroid Patients

Hashimoto Thyroiditis (HT) is the most common autoimmune thyroid disease and the commonest cause of hypothyroidism. C-reactive protein (CRP) is synthesized in hepatocyte in response to autoimmune disorders; strongly induced by IL-6. This study aimed to estimate serum IL-6 and CRP levels in autoimmune and non- autoimmune hypothyroidism. The present study included 60 Iraqi female hypothyroid patients divided to 30 autoimmune and 30 non-autoimmune, with age ranged between 24-50 years and 30 healthy controls with age ranged between 27-52 years. Serum samples were collected from study groups. The levels of thyroid hormones (TSH, T4 and T3) were determined by using automated Chemiluminescence Immunoassay (CLIA) analysis system. Detection the levels of thyroid peroxidase antibody (TPO-Ab), thyroglobulin antibody (TgAb) and Interluekin-6 by enzyme linked immunosorbent assay (ELISA) kits. While latex agglutination slide test used for determination the presence of serum CRP. The current results revealed that serum TSH, TPO-Ab, Tg-Ab, IL-6 levels and CRP positive ratio are increased significantly (P<0.01) in autoimmune hypothyroid group as compared with non- autoimmune hypothyroid group and control group. But there are no significant differences (p?0.05) between non- autoimmune hypothyroid patient and control in the level of TSH, T4, T3, TPO-Ab, Tg-Ab, IL-6. Only the positive ratio of CRP is elevated significantly than ratio in control. This study showed significant increase (P<0.01) in IL-6 level and CRP positive ratio in autoimmune hypothyroidism, that indicates to the effect of autoimmune thyroid disease on inflammatory markers IL-6 and CRP in the serum; and increase CRP positive ratio in non-autoimmune hypothyroidism suggested the alteration in the levels of inflammatory marker has been independent from etiology of thyroid disease.

Occurrence of methicillin resistant Staphylococcus aureus in chickens and farm personnel in Sokoto, North-western Nigeria

Objective: The study was conducted to determine the presence of methicillin resistant Staphylococcus aureus (MRSA) in chickens and farm personnel in Sokoto, North-western Nigeria. Materials and method: A total of 160 samples (136 from chickens and 14 from personnel) were collected and screened for the presence of MRSA using cultural characteristics, biochemical tests and latex slide agglutination test for the presence of Penicillin binding protein 2α (PBP2α). Results: MRSA were detected in 8.82% (n=12/136) of chickens, while 14.29% (n=2/14) in farm personnel. All the isolates were positive for PBP2α. Conclusion: This study established for the first time the occurrence of MRSA in both chickens and farm personnel from poultry farms in Sokoto, Nigeria. Thus, the study provided baseline information for further studies on the epidemiology of MRSA.

Maternal colonization of group B streptococcus: prevalence, associated factors and antimicrobial resistance.

BACKGROUND AND OBJECTIVESGroup B streptococcus (GBS, Streptococcus agalactiae) can be transferred during delivery to neonates from mothers who are colonized with GBS in the genital tract. GBS can cause sepsis and meningitis in newborns. This study was conducted to determine GBS colonization rates among pregnant women and the antibiotic sensitivity patterns.DESIGN AND SETTINGProspective descriptive study at the Maternity and Children Hospital, Makkah.PATIENTS AND METHODSVaginal swabs from 1328 pregnant women (≥35 weeks of gestation) attending antenatal clinic were cultured in Todd-Hewitt broth supplemented with gentamicin and nalidixic acid. After 36 hours of incubation, subculture was made onto sheep blood agar and incubated in 5% carbon dioxide for 18 to 24 hours. A Microscan Walk Away system was used for the identification and antibiotic susceptibility of GBS isolates. Each isolate was also tested for group B by using latex slide agglutination test. Information such as maternal age, gestational age and parity was collected using a predesigned questionnaire.RESULTSThe study population ranged between ages 17–47 years. The GBS colonization in all age groups was found to be 13.4%. A higher colonization rate was seen in pregnant women >40 years of age (27.4%). Women with gestational age >42 weeks were colonized (25%) more frequently that women with a gestational age from 41–42 weeks (20.2%). An increased rate of colonization was found in women who delivered >5 times and no colonization in women who delivered once. All GBS isolates were 100% sensitive to penicillin G, ampicillin and vancomycin. Erythromycin and clindamycin showed resistance −15.7% and 5.1%, respectively.CONCLUSIONThe high prevalence of GBS colonization in pregnant women demands for screening in women attending an antenatal clinic so that intrapartum antimicrobial prophylaxis can be offered to all women who are colonized with GBS, thus preventing its transfer to the newborn.

Comparison of rapid methods PBP2′ detection, ORSAB and mecA for detection of methicillin- resistant Staphylococcus aureus (MRSA) in a tertiary care centre, Chennai, India

Method Fifty isolates of MRSA from different specimens like blood, urine, exudates and respiratory were collected from 2010 to 2011. MRSA screen slide latex agglutination test kit (Denka Seikan, Japan) was used for PBP2′ detection and Oxacillin Resistant Screen Agar Base (ORSAB) with supplement (Oxoid Ltd., UK) was used for detection of MRSA from the isolates with ATCC controls. The detection of mecA gene in the MRSA isolates was considered as the reference method for determining the sensitivity of each phenotype rapid method studied.

C-reactive protein in patients with Guillain Barré syndrome.

C-reactive protein (CRP) is an acute phase reactant, widely used as a biomarker for various infectious and inflammatory conditions. Guillain-Barrι syndrome (GBS) is an acute, autoimmune, polyradiculoneuropathy, triggered by infectious agents such as Campylobacter jejuni. GBS is generally precipitated 1-3 weeks following C. jejuni infection which suggests a humoral immunopathogenic mechanism. Basal CRP levels were estimated in sera of patients with GBS and compared with adequate controls. The study population was divided into 4 groups: (i) GBS group included 45 newly diagnosed GBS patients; (ii) Neurological control (NC) group comprised of 59 patients with non-paralytic neurological symptoms/disorders; (iii) Non-neurological controls (NNC) comprised of 43 patients having no neurological symptoms and (iv) Healthy controls (HC) comprised of 101 healthy subjects. CRP was evaluated using slide latex agglutination test (LAT) and enzyme linked immunosorbent assay (ELISA). Statistical analysis was done by the Chi-square test. CRP by LAT was positive in 24.4% GBS group, 34% NC group and 44% NNC group. The range of titer in CRP positive samples in the three patient groups (GBS, NC, NNC) was at concentration of 0.6 mg/dl to 19.2 mg/dl. Similar results were also obtained by ELISA in the patient groups. None of the HC subjects was positive for detectable levels of CRP. High basal level of CRP was detected in patients with GBS. Autoimmune conditions like GBS can stimulate the production of a high level of inflammation resulting in an increase in the CRP production.

Effectiveness of latex agglutination slide test in the diagnosis of imported invasive amoebiasis in the emergency department

We compared a latex agglutination test (LAT) with enzyme-linked immunosorbent assay and indirect hemagglutination assay in the diagnosis of invasive amoebiasis. A retrospective biological records review has included 639 patients for whom these three serological tests were performed. The sensitivity of the LAT was 97.8% and the specificity was 97%.

D-dimer is useful in the diagnosis of cortical venous sinus thrombosis

Estimations of D-dimer correlate with deep vein thrombosis and pulmonary thromboembolism and may serve as a marker of cortical venous sinus thrombosis (CVST). To study the usefulness of D-dimer in the diagnosis of CVST. A total of 26 patients with CVST were subjected to a detailed medical history and neurological evaluation. A cranial MRI was carried out on a 1.5T scanner using T1, T2, and DWI sequences and two-dimensional time of flight MR venography. D-dimer was estimated using a rapid latex agglutination slide test using monoclonal antibodies. The age of patients ranged between 16 and 70 years old (median 31 years old); 8 were males and were examined after a mean duration of 22 days of symptoms. Cortical venous thrombosis was attributed to puerperium in 4 patients, infection in 5 patients, and pregnancy, dehydration, insect bite, and migraine in 1 patient each. Superior sagittal sinus was involved in 15 patients, transverse sinus in 16 patients, straight sinus in 3 patients, sigmoid sinus in 7 patients, and cavernous and deep system in 1 patient each. A total of 12 patients had more than one sinus involvement. D-dimer was positive in 20 patients and correlated with the duration of symptoms but not with the extent of sinus thrombosis and the outcome. D-dimer is useful in patients suspected of CVST and patients with positive test results should be urgently sent for MR imaging.

Comparaison des méthodes phénotypiques par rapport à la PCR pour le dépistage de la résistance à la méticilline chez les staphylocoques à coagulase négative

Appreciation of the frequency, the level and the genetic support of methicillin resistance. Seventy-three strains of coagulase negative staphylococci isolated from various specimens, from January to June 2004, were studied. The phenotypic detection was carried out by disk diffusion test using oxacillin and cefoxitin disks, by the determination of oxacillin Minimal Inhibitor Concentration (E-test), by the oxacillin screening test at a concentration of 4 mug/ml and by the search of the penicillin binding protein PBP2a using the slide latex agglutination test. The results of these methods were compared to PCR of mecA gene. Forty-eight strains carried mecA gene whose 30 were detected by the oxacillin disk, the cefoxitin disk, the oxacillin screening test, the slide latex agglutination test and had a MIC from 24 to 256 mug/ml. Seventeen strains were not detected by oxacillin disk but by cefoxitin disk and the slide latex agglutination test. Among these strains, 13 (76%) had oxacillin MIC from 0.5 to 1,5 mug/ml and not grew on oxacillin agar screening, while 4 (24%) had oxacillin MIC from 6 to 16 mug/ml and grew on this agar. One strain had oxacillin MIC of 0,19 mug/ml and was not detected with any phenotypic method. The determination of oxacillin MIC, the search of the PBP2a or more simply the cefoxitin disk had permitted to detect the strains mecA gene (+) with resistant and pre-resistant phenotype but not the strain with sensible phenotype (2.1%).

Laboratory detection methods for methicillin resistance in coagulase negative Staphylococcus isolated from ophthalmic infections

To evaluate different methods of oxacillin susceptibility testing of ocular isolates, considering polymerase chain reaction (PCR) as the 'gold standard', and to compare the in vitro susceptibility to oxacillin with that of other antimicrobials used in ophthalmologic practice. The Vitek gram-positive identification card was used to identify ocular coagulase negative Staphylococcus species. The presence of the mecA gene was determined by the polymerase chain reaction assay with a combination of two primer sets (mecA and 16S rRNA) in a single region. Results were analyzed and compared with other oxacillin susceptibility methods: PBP2a detection by rapid slide latex agglutination test (SLA); oxacillin E-test; the Vitek automated gram-positive susceptibility card (GPS-105); the oxacillin salt agar screening test (OSAS) at a concentration of 6.0, 1.0 and 0.75 microg oxacillin per ml and the cefoxitin disk diffusion test (CDD). Automated susceptibility was also determined to other antimicrobial agents (fluoroquinolones, penicillin G, amoxicillin-ampicillin, cefazolin, ampicillin-sulbactam, erythromycin, clindamycin, gentamicin, tetracycline, trimethoprim-sulfamethoxazole, vancomycin and rifampin. Of the 69 CoNS isolates tested, 71% were mecA-positive and 29% mecA-negative. All methods tested had a statistically significant agreement with polymerase chain reaction. There was a tendency of positive polymerase chain reaction predomination among the S. epidermidis isolates in comparison to non-epidermidis isolates, although this was not statistically significant (78.3% vs. 56.5%; chi2= 2.54; P= 0.11). The oxacillin salt agar screening test (0.75 microg oxacillin/ml) showed the best performance, with 100% sensitivity and negative predictive value; 95% specificity and 98% positive predictive value. Using the E-test, the mecA-positive isolates were statistically significantly more resistant to ciprofloxacin, ofloxacin, gatifloxacin and moxifloxacin (P= 0.002; P= 0.008; P= 0.002 and P= 0.003, respectively). There was a statistically significant higher proportion of resistance of the coagulase negative Staphylococcus mecA-positives for: penicillin G, amoxicillin-ampicillin, cefazolin, ampicillin-sulbactam, erythromycin, clindamycin, gentamicin and tetracycline (P< or =0.05). All coagulase negative Staphylococcus species were susceptible to vancomycin and there was no statistically significant correlation between the mecA-positive isolates and resistance to trimethoprim-sulfamethoxazole or to rifampin. In the present study, we found that the E-test and the oxacillin salt agar screening test S (0.75 microg oxacillin per ml), when compared with polymerase chain reaction, were the most accurate currently available methods to phenotypically detect oxacillin resistance of coagulase negative Staphylococcus species. This study demonstrated that a good option for screening of ocular isolates for oxacillin resistance in the microbiology laboratory is the cefoxitin disk diffusion test and the automated Vitek system. We believe it is important to have available methods that accurately detect methicillin resistance of the less commonly encountered species, chiefly because of their increasing importance as opportunistic pathogens.

Performance of TechLab C. DIFF QUIK CHEK™ and TechLab C. DIFFICILE TOX A/B II™ for the detection of Clostridium difficile in stool samples

Two membrane-bound enzyme immunoassays by TechLab, Blacksburg, VA, were evaluated and compared with the Triage® Micro C. difficile Panel (Biosite Diagnostics, San Diego, CA), with culture, and with cytotoxic assay. The TechLab panels were C. DIFF QUIK CHEK™ (QC-GDH) and C. DIFFICILE TOX A/B II™ (QC-toxinA/B), which detect glutamate dehydrogenase (GDH) and Clostridium difficile toxins A and B, respectively. The Triage Panel detects GDH (TR-GDH) and toxin A (TR-toxinA). Methods Stool samples were inoculated onto CCFA plates (Q-Labs, Quebec, Canada) after alcohol shock, and suspected colonies were identified by the MicroScreen C. difficile latex slide agglutination test (Microgen Bioproducts, Surrey, UK). TR-GDH, TR-toxinA, QC-GDH, and QC-toxinA/B tests were performed according to the manufacturers' instructions on all the samples. Samples positive for GDH or culture but negative for TR-toxinA and QC-toxinA/B were further tested by cytotoxin assay (CTA). CTA was also performed on samples that caused blackening of the Triage® Micro C. difficile Panel. Results A total of 313 of 401 stool samples were negative for GDH and toxins (78%). Eighty-eight samples were positive either for GDH or culture or both. Thirteen of these could not be evaluated for C. difficile-associated diarrhea (CDAD) because CTA test was not performed. Toxin/s was detected at least by one method in 46 (11.8%) of 388 samples that were positive for culture or GDH and were considered diagnostic of CDAD. The QC-GDH was more sensitive than culture and TR-GDH for the detection of C. difficile. However, in 18GDH-positive samples positive for either of the Triage or TechLab immunoassays, the culture remained negative. Ten (2%) results of the Triage immunoassays could not be evaluated because of discoloration of the panels. QC-GDH (93.5%) was more sensitive for detecting the presence of toxin-producing C. difficile than TR-GDH (79.5%). TR-toxinA was more specific for detecting the presence of toxin-producing C. difficile than QC-toxinA/B (100% and 96.9%, respectively). Conclusions The GDH tests had a faster turnaround time than the traditional culture methods. QC-GDH was most sensitive for the detection C. difficile-positive stools and was easy to use.

A Slide Latex Agglutination Test for the Rapid Detection of Antibodies in Serum Against Porcine Parvovirus

A slide latex agglutination test (LAT) was developed and evaluated to detect serum antibodies against porcine parvovirus. Porcine parvovirus antigen was obtained by 10% PEG-6000 and 0.5 mol/l sodium chloride precipitation, and inactivated by 0.1% methanal. Two per cent suspensions of latex particles (0.5-0.8 microm) were coated by adding an equal volume of porcine parvovirus antigen at 0.34 microg/ml. Repeatability of latex agglutination test was evaluated with a panel of 100 sera using the same and different antigen lots. A good agreement between LAT and haemagglutination inhibit assay was observed. Because of convenience and speed of performance, this method would be used widely in clinic examination.

Correlation of Penicillin Binding Protein 2a Detection with Oxacillin Resistance in Staphylococcus aureus and Discovery of a Novel Penicillin Binding Protein 2a Mutation

We compared a rapid slide latex agglutination test (LAT; Oxoid, Basingstoke, United Kingdom) that detects penicillin binding protein 2a (PBP2a) with MicroScan conventional panels (Dade Behring, West Sacramento, CA) for detection of oxacillin resistance in Staphylococcus aureus. The PBP2a LAT demonstrated 99% agreement with MicroScan oxacillin MIC results for 388 isolates of S. aureus. All 249 oxacillin-resistant isolates gave strong positive reactions in the LAT (100% sensitivity). Three of the 139 oxacillin-susceptible isolates were also strongly positive and one was weakly positive in the LAT (97.1% specificity). The three oxacillin-susceptible isolates with strongly positive reactions were further characterized. The mecA gene was detected in all three by PCR; one isolate was determined to be resistant to oxacillin by reference broth microdilution testing (MIC, 8 microg/ml), one isolate was inducibly resistant to oxacillin (MIC of 16 microg/ml after overnight induction), and one isolate remained susceptible regardless of the method used for testing. Sequence analysis of a 2.1-kb gene fragment of the mecA gene from the susceptible isolate revealed a one-base substitution at nucleotide position 1449 which results in a Met-to-Ile change for amino acid residue 483. This amino acid substitution has not been previously reported and may be associated with a change in the function of PBP2a resulting in oxacillin susceptibility. An additional 487 isolates were tested in parallel with the both the LAT and MicroScan panels using criteria in which only strong (3 to 4+) or repeatedly weak (1 to 2+) LAT reactions were considered positive, and the results showed 99.4% agreement. The PBP2a LAT provided rapid and reliable detection of oxacillin resistance and proved a useful adjunct to the phenotypic method. Both methods provided reliable detection of oxacillin-resistant S. aureus and facilitated the discovery of a novel, functionally impaired form of PBP2a.

Genotypic versus phenotypic characterization, with respect to susceptibility and identification, of 17 clinical isolates of Staphylococcus lugdunensis

To compare different methods for the identification and determination of susceptibility to penicillin and methicillin of Staphylococcus lugdunensis. Seventeen clinical isolates of S. lugdunensis (identified by PCR amplification and sequencing of the rpoB gene) were studied using the ATB32-Staph, Crystal, Vitek 2 and Wider commercial systems. The clumping factor test and the tube coagulase test were also performed. Beta-lactamase production was studied by chromogenic methods. Methicillin resistance was phenotypically studied by the MRSA slide latex agglutination test, growth in MRSA agar, and the Vitek 2 and Wider systems (based on oxacillin MIC), and genotypically studied by detection of the mecA gene by PCR. The clumping factor test was negative in 35.3% of strains. All isolates were correctly identified to species level by the ATB32-Staph system. Species misidentification rates were 5.9%, 23.5% and 29.4% with the Crystal, the Vitek 2 and the Wider systems, respectively, mostly as Staphylococcus haemolyticus. Beta-lactamase was present in 11.8% of strains. Whereas 76.5% and 47.1% of strains exhibited oxacillin resistance (MIC range 0.5-2 mg/L) by the Vitek 2 system and the Wider system, respectively, none of the strains was positive in the MRSA slide latex agglutination test or grew in MRSA agar. All strains lacked the mecA gene. The clumping factor test and some commercial systems may misidentify S. lugdunensis. Oxacillin resistance detected by commercial systems is not indicative of the presence of the mecA gene. These facts, together with beta-lactamase production, may preclude adequate treatment of infections by this virulent coagulase-negative Staphylococcus.

Immunoglobulin E-rheumatoid factor in juvenile rheumatoid arthritis.

To determine the presence of immunoglobulin E-rheumatoid factor in patients with juvenile rheumatoid arthritis and to correlate it with clinical and laboratory parameters. A multicenter prospective study was carried out from January 1993 to January 1999 with the enrollment of 3 centers of pediatric rheumatology. Ninety-one children with juvenile rheumatoid arthritis diagnosed according to the American College of Rheumatology criteria were studied: 38 (42%) with systemic, 28 (31%) with pauciarticular, and 25 (27%) with polyarticular onset. Ages ranged from 2.1 years to 22.6 years (mean 10.5 +/- 4.7), with 59 (65%) girls. The control group consisted of 45 healthy children. The detection of immunoglobulin E-rheumatoid factor was carried out utilizing an enzyme-linked immunosorbent assay. Associations of immunoglobulin E-rheumatoid factor with immunoglobulin M-rheumatoid factor (latex agglutination test), total serum immunoglobulin E, erythrocyte sedimentation rate, antinuclear antibody, and functional and radiological classes III or IV were analyzed. Positive immunoglobulin E-rheumatoid factor was found in 15 (16.5%) of the 91 children with juvenile rheumatoid arthritis: 7 (18.5%) with systemic, 5 (18%) with pauciarticular, and 3 (12%) with polyarticular onset. A significant correlation was observed between immunoglobulin E-rheumatoid factor and total serum immunoglobulin E in the juvenile rheumatoid arthritis patients. No correlation was found between immunoglobulin E-rheumatoid factor and positive latex agglutination slide test, erythrocyte sedimentation rate, antinuclear antibody, or the functional and radiological classes III or IV in any disease onset group. In 4 out of 45 control children (8.9%), immunoglobulin E-rheumatoid factor was positive but with no correlation with total serum immunoglobulin E levels. Immunoglobulin E-rheumatoid factor could be detected in 16.5% of juvenile rheumatoid arthritis patients, particularly in those with high levels of total serum immunoglobulin E, and immunoglobulin E-rheumatoid factor appears not to be associated with disease activity or severity.

Evaluation of an anti-PBP 2a slide latex agglutination test in coagulase-negative staphylococci isolated in Greek hospitals

Oxacillin resistance was examined in 258 coagulase-negative staphylococci from Greek hospitals. mecA DNA was detected in 168 isolates, which were also resistant to oxacillin by agar dilution and disk diffusion, according to the current NCCLS breakpoints. Both methods exhibited a relatively low specificity misclassifying 21 and 19 of the 90 mecA-negative isolates respectively as oxacillin resistant. In contrast, an anti-PBP 2a latex agglutination test, applied after induction by oxacillin, correctly classified 163 mecA-positive (sensitivity 97%) and 88 mecA-negative isolates (specificity 97.7%).