Semiquantitative Culture Research Articles

Ethnic variations in cervical cytokine concentrations and vaginal flora during pregnancy.

Pregnancy-mediated changes in immunity may influence risk of HIV-1 acquisition. This risk appears greatest among non-Caucasian women. Pregnant women with low risk of immune disruption were enrolled in a prospective observational cohort. Study visits occurred each trimester and postpartum. Semi-quantitative vaginal cultures and concentrations of cervical cytokines were compared between Caucasian and non-Caucasian women. In the second trimester, non-Caucasian women were more likely to be colonized with Gardnerella vaginalis (62% versus 25%, P = 0.02) and non-pigmented anaerobic gram-negative rods (43% versus 8%, P = 0.01). Mycoplasma hominis was more frequently isolated in non-Caucasian women throughout the second (29% versus 4%, P = 0.03) and third trimesters (35% versus 6%, P = 0.04). Non-Caucasian women had higher median interleukin (IL)-10 concentrations throughout the second (128 pg/mL versus 7 pg/mL, P = 0.05) and third trimesters (224 pg/mL versus 7 pg/mL, P = 0.05). Non-Caucasian women experienced a greater diversity of microorganisms and increased IL-10 in the second and third trimesters.

Diagnostic accuracy of semi-quantitative and quantitative culture techniques for the diagnosis of catheter-related infections in newborns and molecular typing of isolated microorganisms.

BackgroundCatheter-related bloodstream infections (CR-BSIs) have become the most common cause of healthcare-associated bloodstream infections in neonatal intensive care units (ICUs). Microbiological evidence implicating catheters as the source of bloodstream infection is necessary to establish the diagnosis of CR-BSIs. Semi-quantitative culture is used to determine the presence of microorganisms on the external catheter surface, whereas quantitative culture also isolates microorganisms present inside the catheter. The main objective of this study was to determine the sensitivity and specificity of these two techniques for the diagnosis of CR-BSIs in newborns from a neonatal ICU. In addition, PFGE was used for similarity analysis of the microorganisms isolated from catheters and blood cultures.MethodsSemi-quantitative and quantitative methods were used for the culture of catheter tips obtained from newborns. Strains isolated from catheter tips and blood cultures which exhibited the same antimicrobial susceptibility profile were included in the study as positive cases of CR-BSI. PFGE of the microorganisms isolated from catheters and blood cultures was performed for similarity analysis and detection of clones in the ICU.ResultsA total of 584 catheter tips from 399 patients seen between November 2005 and June 2012 were analyzed. Twenty-nine cases of CR-BSI were confirmed. Coagulase-negative staphylococci (CoNS) were the most frequently isolated microorganisms, including S. epidermidis as the most prevalent species (65.5%), followed by S. haemolyticus (10.3%), yeasts (10.3%), K. pneumoniae (6.9%), S. aureus (3.4%), and E. coli (3.4%). The sensitivity of the semi-quantitative and quantitative techniques was 72.7% and 59.3%, respectively, and specificity was 95.7% and 94.4%. The diagnosis of CR-BSIs based on PFGE analysis of similarity between strains isolated from catheter tips and blood cultures showed 82.6% sensitivity and 100% specificity.ConclusionThe semi-quantitative culture method showed higher sensitivity and specificity for the diagnosis of CR-BSIs in newborns when compared to the quantitative technique. In addition, this method is easier to perform and shows better agreement with the gold standard, and should therefore be recommended for routine clinical laboratory use. PFGE may contribute to the control of CR-BSIs by identifying clusters of microorganisms in neonatal ICUs, providing a means of determining potential cross-infection between patients.

Clinical and microbiologic evaluation of chronic leg ulcers: a cross-sectional study.

This study aimed at evaluating the flora and bacterial load of chronic leg ulcers (CLUs) according to the clinical judgment of colonization or infection. This was an analytical and cross-sectional study. This study was conducted in an outpatient wound care unit in the Dermatology Department of the Botucatu School of Medicine-UNESP, Brazil. The participants were patients with CLUs who did not use systemic antibiotics. The ulcers were clinically divided into 3 groups: ulcers with good granulation tissue (GGT), critical colonization (CC), and infection. Secretion was collected from a 1-cm area using a swab and seeded by the semiquantitative method. The main outcome measures were genus and species of the bacteria found in the cultures and result of the semiquantitative culture correlating with the clinical diagnosis of GGT, CC, and infection. Seventy-seven ulcers were evaluated: 27 with GGT, 29 with CC, and 21 with infection. Gram-negative bacteria were most often found in all groups (81%): Pseudomonas aeruginosa, in granulation and colonized ulcers, and Proteus mirabilis, in infected ulcers. Ulcers from the infected group showed higher bacterial load. The flora of CLUs was predominantly constituted by gram-negative bacteria, and P aeruginosa was the most prevalent. The bacterial load of infected ulcers was higher as compared with the others, although some ulcers with GGT also presented a high load. The interpretation of microbiologic tests based on the swab techniques and even on semiquantitative analysis requires close clinical correlation.

Gram-Stain Plus MALDI-TOF MS (Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry) for a Rapid Diagnosis of Urinary Tract Infection

Microbiological confirmation of a urinary tract infection (UTI) takes 24–48 h. In the meantime, patients are usually given empirical antibiotics, sometimes inappropriately. We assessed the feasibility of sequentially performing a Gram stain and MALDI-TOF MS mass spectrometry (MS) on urine samples to anticipate clinically useful information. In May-June 2012, we randomly selected 1000 urine samples from patients with suspected UTI. All were Gram stained and those yielding bacteria of a single morphotype were processed for MALDI-TOF MS. Our sequential algorithm was correlated with the standard semiquantitative urine culture result as follows: Match, the information provided was anticipative of culture result; Minor error, the information provided was partially anticipative of culture result; Major error, the information provided was incorrect, potentially leading to inappropriate changes in antimicrobial therapy. A positive culture was obtained in 242/1000 samples. The Gram stain revealed a single morphotype in 207 samples, which were subjected to MALDI-TOF MS. The diagnostic performance of the Gram stain was: sensitivity (Se) 81.3%, specificity (Sp) 93.2%, positive predictive value (PPV) 81.3%, negative predictive value (NPV) 93.2%, positive likelihood ratio (+LR) 11.91, negative likelihood ratio (−LR) 0.20 and accuracy 90.0% while that of MALDI-TOF MS was: Se 79.2%, Sp 73.5, +LR 2.99, −LR 0.28 and accuracy 78.3%. The use of both techniques provided information anticipative of the culture result in 82.7% of cases, information with minor errors in 13.4% and information with major errors in 3.9%. Results were available within 1 h. Our serial algorithm provided information that was consistent or showed minor errors for 96.1% of urine samples from patients with suspected UTI. The clinical impacts of this rapid UTI diagnosis strategy need to be assessed through indicators of adequacy of treatment such as a reduced time to appropriate empirical treatment or earlier withdrawal of unnecessary antibiotics.

Modified Methylene Blue Screening Method for Significant Bacteriuria

Urinary tract infection is common in the tropics especially in third world countries. In most regional laboratories the volume of urine specimens requested for culture and sensitivity are so overwhelming that it poses a great pressure on the laboratory staff and also consumes a lot of reagent. Evidence abound to support the fact that less than 50% of all such specimen are positive hence the need for a screening method that will reduce the large quantity of urine specimen that will undergo culture. The screening for significant bacteriuria will therefore obviate the wastage of materials, reagent, hospital manpower and time. The modified methylene blue screening technique was performed by adding 20 μl of methylene blue stain to 10 ml of well mixed urine sample and allowed to stand at room temperature for 5 minutes before reading the absorbance at 540 nm wavelength against water blank. The absorbance of the sample is compared with that of the cut-off value and those that exceed this value are recorded as being positive for significant bacteriuria while those with absorbance below the cut-off value are recorded as being negative and should not be cultured. The results obtained from the screening technique were compared with semiquantitative urine culture results. A total of 2683 samples were assayed, among this 984 (36.68%) had absorbance above the cut-off value and so were recorded as being positive for significant bacteriuria whereas 1699 (63.32%) had absorbance below the cut-off value and were recorded as being negative for significant bacteriuria. When compared with the semiquantitative culture, a total of 933 (34.85%) had isolates with significant bacterial growth of ≥105 CFU/ml while 1748 (65.15%) had either no bacterial growth or non-significant bacterial isolates. The technique showed a sensitivity of 94.82% and a specificity of 97.17%. The difference in significant bacteriuria between the urinary screening technique and culture isolate was statistically significant (p<0.05). We present our technique for further study while we advocate their adoption in clinical laboratories especially in poor resource setting in developing countries.

Prevalence of asymptomatic bacteriuria and its antibacterial susceptibility pattern among pregnant women attending the antenatal clinic at kanpur, India.

Symptomatic and asymptomatic bacteriuria (ASB) is common in pregnant women. Pregnancy enhances the progression from ASB to symptomatic bacteriuria, which if left untreated, could lead to acute pyelonephritis and other adverse outcomes such as prematurity, postpartum, hypertensive disease, anaemia, UTIs and higher foetal mortality rates. To identify the prevalence of ASB, the most common causative microorganisms and the antibacterial susceptibilities of the isolated microorganisms at a tertiary care centre at Kanpur, India. A total number of 300 asymptomatic pregnant women were screened for ASB by urine culture by using a semi quantitative culture method. In this study, significant bacteriuria was found in only 22 cases (7.3%). Growth of contaminants was seen in 40 cases (13.3%). Among cases which showed positive cultures, 48.9% were primigravidae and 51.1% were multigravidae. Highest incidence was reported in age group of 21-30 years. The predominant organisms which were isolated were Escherichia coli, followed by Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus aureus and Proteus mirabilis. Escherichia coli, the most common isolate, was found to be only 61% and 70% sensitive to ampicillin and amoxicillin + clavulanate, respectively. Sensitivity to ceftriaxone and ciprofloxacin was 95%, and sensitivity to amikacin was 99%. Hundred percent sensitivity was found for the broad spectrum pencillins, imipenem, and meropenem. Klebsiella pneumoniae, the second most frequent organism which was grown on culture, was only 11% sensitive to ampicillin, while sensitivity to amoxicillin + clavulanate and cefuroxime was 86%. 100% sensitivity was found for cefepime, ceftriaxone, ciprofloxacin, imipenem and meropenem. Routine urine culture test should be carried out for all antenatal women, to detect asymptomatic bacteriuria, and every positive case should be treated with appropriate antibiotic therapy, to prevent any obstetric complication which is associated with pregnancy.

Diagnosis and Management of Central Venous Catheter-Related Infections

Use of central venous catheters (CVCs) can lead to catheter-related bloodstream infections (CRBSIs) and such infections are associated with serious morbidity and mortality and with increased health care costs. The diagnosis of CRBSI needs to be accurate for adequate management. Semiquantitative catheter tip culture has been established as standard in most laboratories, but this method requires catheter removal. Catheter-sparing diagnostic methods, such as differential quantitative blood cultures and differential time to positivity have emerged as reliable diagnostic techniques. Management of CRBSIs involves deciding on catheter removal and the type and duration of systemic antimicrobial therapy. Such decisions depend on the identity of the organism causing the bloodstream infection and the clinical and radiographic manifestations suggesting a complicated course.

COSMOS Study Microbiological Results: Bacterial Colonization and Infection of Long-Term Peripheral Catheters

Background: Peripheral venous catheters (PVC) have a lower risk of the infection than central venous catheters (CVC), however, their high frequency of use makes PVC a major problem. Nowadays, there is no consensus regarding the diagnosis of PVC infections and current recommendations are not only utopian but can lead to an underestimation of infection rates. Objectives: To compare the incidence of bacterial colonization and CRI. To identify the significant bacterial colonization in CRI, as well as the main pathogens causing bacterial colonization and CRI in long-term PVC. Material and methods: Nurse-driven, randomized controlled trial to compare closed system (COS) versus open system (MOS), where catheters were removal only by clinical-indication and were inserted and maintained in accordance with CDC guidelines, except those that apply to routine replacement recommendations. The blinded Maki’s semiquantitative culture technique was used. ClinicalTrials.gov (NCT00665886). Results: A total of 1183 catheters (631 patients) were randomized, 584 in the COS group (54,173 catheter-hours recorded), and 599 in the MOS group (50,296). 283 PVC were cultured, i.e. 24% of the sample. The mean in-dwell time to onset of event of COS was 239.5 hours compared to 171.9 with MOS. No significant difference in cumulative incidence or incidence density rates per 1000 catheter-days for bacterial colonization, and no statistical significance were found between rates of CRI (COS, 2.2%; MOS, 2.5%). However, we observed a 22% relative risk reduction (RRR) in CRI with COS. Of the 283 cultures, 21.9% were positive, of which the 46.8% were in COS and 53.2% in MOS. There were no significant differences between microorganisms isolated, number of colonies or type of germ. Staphylococcus was responsible for 80.3% of the colonization, and 85.7% of CRI. S. epidermidis was responsible for 48.8% of colonization and 52.4% of CRI. S. aureus was isolated in two cases (9.5%), one in each group. Discussion: As in previous studies, despite a reduction in the incidence of CRI in closed system, the difference did not reach statistical significance. Nine CRI registered in COS were caused by Gram + (100%), while in MOS 9 CRI were recorded by Gram + (75%), 2 by Gram - (16.7%) and one by Candida (8.3%). Our data seems to confirm that bacteria isolated from closed systems are less virulent and/or that these systems may offer protection against CRI. Conclusion: International guidelines for best clinical practice should differentiate CRI from CRBSI in the management of peripheral lines-related infections. No statistical differences exist between rates of CRI. However, there is a RRR of CRI with closed systems. A total of 29% of the catheter cultured were associated with CRI (26.5% in COS, 31.3% in MOS), suggesting less virulence of the bacteria isolated in closed systems or greater protection offered by such systems. In long-term PVC, staphylococci causes 80% of colonizations, and 100% of CRI in closed systems and while only 75% in open. There were no significant differences between isolated bacteria, the number of colonies or the type of pathogen.

Diagnosis of central venous catheter-related bloodstream infection without catheter removal: A prospective observational study

BackgroundCatheter-related bloodstream infections (CRBSI) resulting from bacterial colonisation of an intravascular catheter are the leading cause of nosocomially acquired sepsis contributing significantly towards in-hospital morbidity and mortality. Suspicion of central venous CRBSI leads frequently to catheter withdrawal but not all infection requires the catheter to be withdrawn; therefore, diagnosis of central venous CRBSI without catheter withdrawal is a necessity. MethodsThe study was prospectively performed in a cohort of adult patients who had short term central venous catheter use. The samples collected from each patients included, skin swab from insertion site, swab from catheter hub, paired blood samples from catheter and from the peripheral vein for quantitative blood culture collected within 15 min of each other and catheter-tip sample by cutting off the tip (distal 5-cm segment). All samples were processed immediately. Results50 episodes of clinical sepsis involving 100 patients occurred in the study population. 28 of the episodes were confirmed as CR-BSI (56%). Blood culture from the central venous catheter had the highest sensitivity (71.43%) and the greatest negative predictive value (86.67%). However, the peripheral blood culture was most specific and had the highest positive predictive value (specificity75%; positive predictive value 50%). The most accurate technique was differential quantitative blood cultures (accuracy 72%), followed by semiquantitative superficial cultures (accuracy 68%), although there were no statistically significant differences between values. ConclusionWe recommend combining semiquantitative cultures and peripheral blood cultures to screen for CR-BSI, leaving differential quantitative blood cultures as a confirmatory and more specific technique.

Clinical and Bacteriological Efficacy of Rifampin-Streptomycin Combination for Two Weeks followed by Rifampin and Clarithromycin for Six Weeks for Treatment of Mycobacterium ulcerans Disease

Buruli ulcer, an ulcerating skin disease caused by Mycobacterium ulcerans infection, is common in tropical areas of western Africa. We determined the clinical and microbiological responses to administration of rifampin and streptomycin for 2 weeks followed by administration of rifampin and clarithromycin for 6 weeks in 43 patients with small laboratory-confirmed Buruli lesions and monitored for recurrence-free healing. Bacterial load in tissue samples before and after treatment for 6 and 12 weeks was monitored by semiquantitative culture. The success rate was 93%, and there was no recurrence after a 12-month follow-up. Eight percent had a positive culture 4 weeks after antibiotic treatment, but their lesions went on to heal. The findings indicate that rifampin and clarithromycin can replace rifampin and streptomycin for the continuation phase after rifampin and streptomycin administration for 2 weeks without any apparent loss of efficacy.

Risk of Repeated Moraxella catarrhalis Colonization Is Increased in Children With Toll-like Receptor 4 Asp299Gly Polymorphism

Moraxella catarrhalis is a common causative agent of acute otitis media and other respiratory infections in children. Toll-like receptor (TLR) 4 is an important protein of human innate immunity. One polymorphic site Asp299Gly of TLR4 is proven to result in an impaired response to lipopolysaccharide from Gram-negative bacteria. We investigated whether Finnish children who carry Asp299Gly had increased risk of M. catarrhalis colonization during their first 2 years of life. This was a prospective cohort study carried out in Turku, Finland. We studied M. catarrhalis colonization in 161 Finnish children, whose nasopharyngeal specimens were taken at 2, 12 and 24 months of age. The semiquantitative culture method was used for identification of different bacterial species and the pyrosequencing-based method for detection of TLR4 Asp299Gly. Of 161 subjects, 126 (78%) were TLR4 A/A wild type and 35 (22%) were A/G heterozygote variants. The prevalence of M. catarrhalis increased from 24% at 2 months to 48% at 12 months and to 58% at 24 months of age. Of the 35 subjects with TLR4 variant, 15 (43%) were M. catarrhalis positive at all 3 time points, whereas only 11 (9%) subjects with TLR4 wild type were positive at these time points (relative risk 4.91, 95% confidence interval: 2.482-9.711, P=0.0001). Moreover, subjects with TLR4 variant had significantly higher bacterial load of M. catarrhalis in their nasopharynx than those with TLR4 wild type (P=0.0032). Our results indicate that children with TLR4 Asp299Gly polymorphism have an increased risk of repeated M. catarrhalis colonization.

Evaluation of semi-quantitative scoring of Gram staining or semi-quantitative culture for the diagnosis of ventilator-associated pneumonia: a retrospective comparison with quantitative culture.

BackgroundSemi-quantitative Gram stain and culture methods are still commonly used for diagnosing ventilator-associated pneumonia (VAP), due to its convenience. Only a few studies, however, have assessed the reliability of these methods when compared with quantitative cultures, a current standard for the diagnosis of VAP. The objective of this study was to assess the utility of semi-quantitative scores obtained using Gram stains and cultures of endotracheal aspirates when compared with quantitative cultures in the diagnosis of VAP.MethodsA retrospective chart review of mechanically ventilated patients with clinically suspected VAP in a single intensive care unit was performed. Semi-quantitative scores of Gram stains or culture results were compared with quantitative culture results of endotracheal aspirate for the diagnosis of VAP in 136 samples for 51 patients.ResultsThe semi-quantitative scores of Gram stains and the semi-quantitative culture results significantly correlated with the log value of the quantitative culture results (rs = 0.64 and 0.75). When using a log count ≥6 of quantitative cultures as the reference standard for the diagnosis of VAP, the sensitivity and specificity was 95% and 61% for Gram stain score of ≥1+, and was 42% and 96% for Gram stain score ≥3+, respectively. The sensitivity and specificity was 96% and 40% for the semi-quantitative culture score of ≥2+, and was 59% and 86% for the semi-quantitative culture score of ≥3+, respectively.ConclusionsAbsence of bacteria in semi-quantitative Gram stain and poor growth (≤1+) in semi-quantitative culture method could be utilized to exclude the possibility of VAP, whereas detection of abundant (≥3+) bacteria in semi-quantitative Gram stain could be utilized to strongly suspect VAP.

Antimicrobial Susceptibility Pattern of Escherichia coli Isolated from Uninary Tract Infected Patients Attending Bir Hospital

Correction: on 23/08/2014, the spelling of 'Uninary' in the title was changed to 'Urinary'.Antibiotic resistance among uropathogens is emerging public health problem. This study was done for assessing antibiotic and multidrug resistance (MDR) patterns of Escherichia coli at Bir Hospital, Kathmandu, among suspected urinary tract infection (UTI) patients from January to March, 2011. Altogether, 739 urine samples were analysed by semi-quantitative culture method and uropathogens were identified by conventional methods. E. coli was tested (109 samples) for antimicrobial susceptibility by Kirby Bauer disc diffusion method as per Clinical and Laboratory Standard Institute (CLSI) guidelines. Out of 739 samples, 27.3% gave significant growth of E. coli while 3.1% and 29.2% samples gave mixed and non-significant growth respectively. E. coli was found to be most predominant isolate (54.0%) followed by coagulase negative Staphylococci (CoNS) (21.3%) and Enterococcus spp. (7.3%). Nitrofurantoin was found to be the most effective antibiotic followed by ciprofloxacin and ofloxacin while cephalexin was least effective. Out of 109 E. coli isolates, 90.8% were MDR strains and most of the isolates had a very high multiple antibiotic resistance (MAR) index, suggesting the origin of the isolates to be of high antibiotic usage. E. coli showed higher rate of resistance towards commonly used oral antibiotics. However, nitrofurantoin is still active against organisms. Thus, nitrofurantoin could be the choice for empirical therapy of UTI. Nepal Journal of Science and Technology Vol. 14, No. 1 (2013) 177-184 DOI: http://dx.doi.org/10.3126/njst.v14i1.8938

Diagnosis of ventilator-associated pneumonia

The aim is to discuss the clinical, microbiologic, and radiological criteria used in the diagnosis of ventilator-associated pneumonia (VAP), distinguish between ventilator-associated tracheobronchitis (VAT) and VAP, and reconcile the proposed Centers for Disease Control surveillance criteria with clinical practice. Numerous ventilator-associated complications (VACs), including VAP and VAT, may occur in critically ill, intubated patients. A variety of definitions for identifying VAP have been proposed, but there is no diagnostic gold standard. The proposed surveillance definition will identify infectious and noninfectious VAC, including VAP and VAT, but this definition may be inadequate for clinical practice. The clinical characteristics of VAP and VAT are similar and include fever, leukocytosis, and purulent sputum. An infiltrate on chest radiograph is consistent with VAP but lacks diagnostic precision, so it is not a criterion in the proposed surveillance definition and should be interpreted cautiously by clinicians. Microbiologically, quantitative and semiquantitative endotracheal aspirate cultures may be employed to diagnose VAP and VAT. Positive bronchoalveolar lavage and protected specimen brush cultures are useful only for the diagnosis of VAP. Experts should collaborate to develop consensus definitions for VAP and VAT that can be applied in practice.

Diagnostic accuracy of UriSed automated urine microscopic sediment analyzer and dipstick parameters in predicting urine culture test results

IntroductionUrinary tract infection (UTI) is one of the most common types of infection. Currently, diagnosis is primarily based on microbiologic culture, which is time- and labor-consuming. The aim of this study was to assess the diagnostic accuracy of urinalysis results from UriSed (77 Electronica, Budapest, Hungary), an automated microscopic image-based sediment analyzer, in predicting positive urine cultures.Materials and methods:We examined a total of 384 urine specimens from hospitalized patients and outpatients attending our hospital on the same day for urinalysis, dipstick tests and semi-quantitative urine culture. The urinalysis results were compared with those of conventional semi-quantitative urine culture.Results:Of 384 urinary specimens, 68 were positive for bacteriuria by culture, and were thus considered true positives. Comparison of these results with those obtained from the UriSed analyzer indicated that the analyzer had a specificity of 91.1%, a sensitivity of 47.0%, a positive predictive value (PPV) of 53.3% (95% confidence interval (CI) = 40.8–65.3), and a negative predictive value (NPV) of 88.8% (95% Cl = 85.0–91.8%). The accuracy was 83.3% when the urine leukocyte parameter was used, 76.8% when bacteriuria analysis of urinary sediment was used, and 85.1% when the bacteriuria and leukocyturia parameters were combined. The presence of nitrite was the best indicator of culture positivity (99.3% specificity) but had a negative likelihood ratio of 0.7, indicating that it was not a reliable clinical test.Conclusions:Although the specificity of the UriSed analyzer was within acceptable limits, the sensitivity value was low. Thus, UriSed urinalysis results do not accurately predict the outcome of culture.

Comparative Analysis of Colony Counts of Different Species of Oral Streptococci in Saliva of Dentulous, Edentulous and in those Wearing Partial and Complete Dentures

To study and compare the number of colony forming units of Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius, Streptococcus mitis and Streptococcus milleri in dentulous, edentulous and in those wearing partial and complete dentures by using semi-quantitative culture method of saliva samples with calibrated standard loop. Sterile specimen collection bottles, Mitis salivarius agar plates, Standard loop, Candle jar, Incubator, Colony counter. Study population consisted of 100 subjects with 25 in each group, with an age range of 40 to 80 years, who were attending the Department of Community Dentistry and Prosthodontics at MNR Dental College, Sangareddy, Hyderabad. Unstimulated saliva samples were collected from patients and inoculated on to Mitis salivarius agar plates using calibrated standard loop. The plates were then incubated anaerobically at 37°C for 24 hours and left at room temperature for further 24 hours. Using a colony counter, the number of colonies of each species was counted. Streptococcus mutans and Streptococcus mitis predominates in the dentulous group, Streptococcus sanguis in complete denture group, Streptococcus salivarius in edentulous group and Streptococcus milleri in removable partial denture group. The results of our study are in accordance with the previous studies, which have sought to differentiate different groups of mutans streptococci using a simple calibrated standard loop.

The role of endotracheal aspirate culture in the diagnosis of ventilator-associated pneumonia: a meta analysis

To investigate the role of endotracheal aspirate (EA) culture in the diagnosis and antibiotic management in ventilator-associated pneumonia (VAP). We searched CNKI, Wanfang, PUBMED and EMBASE databases published from January 1990 to December 2011, to find relevant literatures on VAP microbiological diagnostic techniques including EA and bronchoalveolar lavage (BALF). The following key words were used: ventilator associated pneumonia, diagnosis and adult. Meta-analysis was performed and the sensitivity and specificity of EA on VAP diagnosis were calculated. Our literature search identified 1665 potential articles, 8 of which fulfilled our selection criteria including 561 patients with paired cultures. Using BALF quantitative culture as reference standard, the sensitivity and specificity of EA were 72% and 71%. When considering quantitative culture of EA only, the sensitivity and specificity improved to 90% and 65%, while the positive and the negative predictive values were 68% and 89% respectively. However, the sensitivity and specificity of semi-quantitative culture of EA were only 50% and 80%, with a positive predictive value of 77% and a negative predictive value of 58% respectively. EA culture had relatively poor sensitivity and specificity, although quantitative culture of EA only could improve the sensitivity. Initiating therapy on the basis of EA quantitative culture may still result in excessive antibiotic usage. Our data suggested that EA could provide some information for clinical decision but could not replace the role of BALF quantitative culture in VAP diagnosis.

Quantitative PCR confirms culture as the gold standard for detection of lower airway infection by nontypeable Haemophilus influenzae in Australian Indigenous children with bronchiectasis

Correlation was observed between quantitative PCR and semi-quantitative culture for definition of Haemophilus influenzae infection in bronchoalveolar lavage specimens from 81 children with bronchiectasis. However, qPCR data correlated less well with airway neutrophilia, and supports continued use of culture as the gold standard for defining H. influenzae lower airway infection.

A comparative assessment of two conservative methods for the diagnosis of catheter-related infection in critically ill patients

To assess the utility of two in situ techniques, differential time to positivity (DTP) and semiquantitative superficial cultures (SQSC) for diagnosing catheter-related bloodstream infection (CR-BSI) in critically ill adults. This was a prospective cohort study in patients with suspected CR-BSI arising from a short-term arterial catheter (AC) or a central venous catheter (CVC). On suspicion of CR-BSI, devices were removed. Blood, skin, catheter tip and hub cultures were taken. Infection rates were compared against the diagnosis of CR-BSI using matched tip and blood cultures. Of 120 episodes of clinically suspected CR-BSI in 101 patients examined, 9 (7.5 %) were confirmed as CR-BSI. Validity values (95 % CI) for the diagnosis of CR-BSI arising from both AC and CVC for DTP were: sensitivity 44 % (15-77 %), specificity 98 % (93-100 %), positive predictive value (PPV) 67 % (24-94 %), negative predictive value (NPV) 96 % (90-98 %), positive likelihood ratio (LR+) 25 (5-117), negative likelihood ratio (LR-) 0.6 (0.3-1.0), diagnostic odds ratio (DOR) 44 (7-258), and accuracy 94 % (92-98 %). Validity values (95 % CI) for SQSC were: sensitivity 78 % (41-96 %), specificity 60 % (50-69 %), PPV 14 % (6-26 %), NPV 97 % (89-99 %), LR+ 1.9 (1.0-2.3), LR- 0.4 (0.1-1.3), DOR 5.1 (1.1-19), and accuracy 61 % (51-69 %). DTP combined with SQSC improved sensitivity and NPV to 100 % whilst the DOR increased to 25.8 (95 % CI 3-454). CR-BSI can be ruled out by undertaking DTP and SQSC concurrently for both ACs and CVCs with 100 % sensitivity and NPV.

Role of Peripherally Inserted Central Catheters in Home Parenteral Nutrition

Home parenteral nutrition (HPN) has become a common therapy, with tunneled central venous catheters (CVCs) being preferred for its administration. Peripherally inserted central catheters (PICCs) are not currently recommended for long-term HPN, although evidence to support this statement is scarce. The authors aimed to evaluate the outcomes of HPN, focusing on CVC-related complications. All patients attended at the authors' center for HPN from 2007-2011 were prospectively included. HPN composition aimed at 20-35 kcal/kg/d, 3-6 g/kg/d of glucose, 1.0 g/kg/d of amino acids, and <1 g/kg/d of lipids. HPN was infused in an intermittent schedule, mostly at night. Catheter-related bloodstream infections (CRBSIs) were confirmed with positive semi-quantitative or quantitative culture of the catheter or simultaneous differential blood cultures drawn through the CVC and peripheral vein. Seventy-two patients received HPN, with 79 implanted CVCs (48 PICCs, 10 Hickman, and 21 ports). Mean catheter-days were 129.1 for PICCs, 98.5 for Hickman, and 67.7 for ports (P = .685). When analyzing CRBSIs, ports had 44, Hickman had 20, and PICC had 0 episodes per 1000 catheter-days (P = .078). Only PICCs showed less incidence of CRBSIs vs ports (P = .043). Multivariate logistic regression, correcting by catheter-days, patients' age and sex, underlying disease, and type of catheter, showed that only catheter-days (P = .031) was a predictor for CRBSIs (P = .007, Nagelkerke R= = 0.246). PICCs are similar in terms of catheter-related complications to other CVCs for the administration of HPN, especially for oncology patients with HPN lasting <6 months.