The role of rapid testing and clinical decision in the diagnosis of human influenza A H1N1 infection.

OBJECTIVE: To evaluate the role of the rapid influenza diagnostic test (RIDT) and clinical decision in the diagnosis of H1N1. METHODS: In November 2009, 290 suspected influenza patients were examined for H1N1 during an outbreak in Riyadh, Saudi Arabia. Nasopharyngeal swabs were analyzed using Directigen EZ Flu A+B kit. Monoclonal anti-human influenza A/B and reverse transcription- polymerase chain reaction (RT-PCR) were used. Positive and negative controls were used in each run of specimens. Validity indices were calculated for RIDT and clinical diagnostic criteria. RESULTS: The sensitivity and specificity of RIDT were 40.5% (95% confidence interval [CI]: 33.0-48.5), and 94.5% (95% CI: 88.6-97.6). The sensitivity of clinical decision was 66.3% (95% CI: 58.4-73.4), and the specificity was 65.4% (95% CI: 56.3-73.4). The sensitivity of clinical decision was higher in early presenters (79.2%; 95% CI: 57.3-92.1). The RIDT sensitivity was higher in younger patients (48.4%; 95% CI: 35.7-61.3). The positive predictive value (PPV) was 90.4% (95% CI: 80.7-95.7) for RIDT, and 71.1% (95% CI: 63.1-78.0) for clinical decision. The PPV for RIDT was greater for older (94.7%; 95% CI: 80.9-99.1) and late (90.7%; 95% CI: 76.9-97.0) presenters. The adjusted odds ratio for clinical decision was significant for cough, headache, and fatigue. CONCLUSION: The RIDT can be useful in epidemics and high prevalence areas, whereas clinical decision, and RT-PCR complement the diagnosis of H1N1 in any setting.

Helicobacter pylori virulence markers in gastroduodenal disorders. Detection of cytotoxin-associated gene A and vacuolating cytotoxin-associated gene A genes in Saudi patients.

OBJECTIVE: To detect the presence of virulence markers cytotoxin-associated (cagA) and vacuolating cytotoxin-associated (vacA) genes in gastric biopsy specimens of patients with gastroduodenal disorders. METHODS: This study was conducted at the Department of Pathology, King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia between March 2008 and February 2009. A total of 118 gastric biopsy specimens from 81 males and 37 females (mean age: 55 +/- 18 years) with histological evidence for the presence of Helicobacter pylori (H. pylori) were included in the study. The H. pylori cagA and vacA genes were detected using polymerase chain reaction-enzyme-linked immunosorbent assay technique. RESULTS: Both H. pylori cagA and vacA genes were detected in 60 (51%) patients. Forty-one (35%) patients had active chronic gastritis, 22 (54%) harbored cagA, and 25 (61%) had vacA gene. Twenty-six (22%) patients had duodenal ulcer, 14 (54%) had cagA, and 15 (58%) had vacA genes. Eighteen (15%) patients had active acute gastritis, 8 (44%) carrying cagA gene, and 12 (67%) had vacA gene. The cagA and vacA genes co-existed in all the 17 (100%) patients with adenocarcinoma. These genes coexisted in 44% biopsies from active acute gastritis, and 46% each in duodenal ulcer and active chronic gastritis. CONCLUSION: The cagA and vacA genes as H. pylori virulence markers were detected in gastroduodenal disorders, and their remarkably high co-existence in adenocarcinoma prompt further investigations for evaluating H. pylori as a direct carcinogen.

A validation study comparing the sensitivity and specificity of the new Dr. KSU H1N1 RT-PCR kit with real-time RT-PCR for diagnosing influenza A (H1N1).

BACKGROUND AND OBJECTIVES: A new test (Dr. KSU H1N1 RT-PCR kit) was recently developed to provide a less expensive alternative to real-time reverse transcriptase-polymerase chain reaction (RT-PCR). We report the findings of a validation study designed to assess the diagnostic accuracy, including sensitivity and specificity, of the new kit, as compared to real-time RT-PCR. DESIGN AND SETTING: Cross-sectional validation study conducted from 18-22 November 2009 at a primary care clinic for H1N1 at a tertiary care teaching hospital in Riyadh. PATIENTS AND METHODS: Nasopharyngeal swab samples and data on socio-demographic characteristics and symptoms were collected from 186 patients. Swab samples were sent to the laboratory for testing with both real-time RT-PCR and the new Dr. KSU H1N1 RT-PCR kit. We measured the sensitivity and specificity of the new test across the entire sample size and investigated how these values were affected by patient socio-demographic characteristics and symptoms. RESULTS: The outcomes of the two tests were highly correlated (kappa=0.85; P<.0001). The sensitivity and specificity of the new test were 99.11% and 83.78%, respectively. The sensitivity of the new test was affected only minimally (96%-100%) by patient characteristics and number of symptoms. On the other hand, the specificity of the new test varied depending on how soon patients were tested after onset of symptoms (100% specificity when swabs were taken on the first day of the symptoms, decreasing to 75% when swabs were taken on or after the third day). The specificity of the new test also increased with increasing body temperature. CONCLUSION: The new test seems to provide a cost-effective alternative to real-time RT-PCR for diagnosing H1N1 influenza. However, further testing may be needed to verify the efficacy of the test in different settings and communities.

Antimicrobial activity of tigecycline against bacterial isolates from intensive care units in a teaching hospital in Central Saudi Arabia.

OBJECTIVE: To test the activity of tigecycline against bacterial isolates including multi-drug resistant (MDR) gram negative and gram positive organisms from intensive care patients. METHODS: Clinically significant gram positive and MDR gram negative isolates from specimens of patients in the intensive care units of King Khalid University Hospital (KKUH), Riyadh, Kingdom of Saudi Arbia between November 1, 2006 and December 31, 2008 were tested against tigecycline by disc diffusion (DD) method. In some isolates, the minimal inhibitory concentration was carried out by E-test method. Some of the gram negative isolates, and gram positive isolates were tested using both methods. The study was approved by the hospital ethics committee. RESULTS: All the 83 gram positive organisms tested by both DD and E-test were susceptible to tigecycline. Two hundred and fifty-four MDR gram negative isolates were tested for susceptibility to tigecycline. Of these 176 tested by DD, 159 (90%) were susceptible, 6 (3.4%) were resistant, and 11 (6.2%) were intermediately susceptible (data are not the same in table 3). From the 188 isolates tested by E-test, 140 (74.4%) were susceptible, 35 (18.6%) were resistant, and 13 (6.9%) showed intermediate susceptibility. For comparison between the methods, 109 isolates of the MDR gram negative organisms were tested by both E test and DD. The difference between the 2 methods was not significant. CONCLUSION: Tigecycline was active against gram positive and most MDR gram negative isolates from patients in medical and surgical intensive cases in KKUH. There was no significant difference between the DD and E-test methods for susceptibility testing of tigecycline against these isolates.

Adherent biofilms in adenotonsillar diseases in children.

OBJECTIVE: To study biofilm formation on the epithelial surfaces of tonsils and adenoids in children undergoing adenotonsillectomy (T&A). DESIGN: Prospective study. SETTING: Tertiary academic hospital. PATIENTS: Between September 2005 and August 2006, 76 patients (mean [SD] age, 5.7 [3.3] years; age range, 1-18 years; male-female ratio, 1.8:1) undergoing T&A to treat infection, obstruction, or both were included. Of these, 44 had obstruction (58%), 26 had infection (34%), and 6 had both (8%). INTERVENTIONS: Scanning electron microscopy was used to assess for the presence of biofilms. MAIN OUTCOME MEASURE: Presence of adherent biofilms on the surface epithelium of tonsils and adenoids. RESULTS: Adherent biofilm formation was demonstrated in 46 patients (61%). Among 26 patients with infections, adherent biofilm formation was detected in 22 (85%), whereas in the group of 44 patients with obstruction only 18 were found to have biofilms (41%). Comparative analysis of the data revealed that the difference was statistically significant (P = .01). CONCLUSIONS: Biofilms were identified on the surfaces of infected or enlarged tonsils and adenoids in most patients undergoing T&A. The presence of biofilms in a significantly higher proportion of patients with chronically inflamed tonsils and adenoids vs patients with obstruction indicates an association between the presence of biofilms and chronic inflammation.

A study of bacterial isolates from corneal specimens and their antibiotic resistance profile.

OBJECTIVE: We aim to examine the spectrum of bacteria causing corneal infections and their antibiotic susceptibility patterns. This will serve as a guideline for empiric therapy of corneal infections. METHODS: We conducted the study over a period of 18 months from March 2001 through December 2002 in King Abdul-Aziz University Hospital, Riyadh, Kingdom of Saudi Arabia. Corneal specimens taken from 200 patients were inoculated directly onto different types of media. The isolates were identified and then tested against the appropriate topical or systemic antibiotics. RESULTS: Sixty-seven (33.5%) of the total specimens were culture positive and 133 (66.5%) were culture negative. Fourteen (7%) of these showed organisms in the Gram stained smears and correlated well with the culture reports. Of the 67 positive cultures, 53 (79.1%) were Gram-positive bacteria mostly coagulase-negative Staphylococci 29 (43.3%) followed by Streptococcus pneumoniae (S. pneumoniae) 13 (19.4%). Among Gram-negative bacteria 14 (20.9%), Pseudomonas aeruginosa (P. aeruginosa) 10 (14.9%) was the predominant isolate. All the isolates were sensitive to ofloxacin and the commonly used ocular antibiotics. CONCLUSION: All the isolated bacteria were sensitive to ofloxacin, a fluoroquinolone. Having marked potency for broad-spectrum activity against both Gram-positive and Gram-negative bacteria, make the fluoroquinolones especially the newer generations, a potential single drug therapy for corneal infections.