Direct Sputum Smear Microscopy Research Articles

Feasibility of magnetic bead technology for concentration of mycobacteria in sputum prior to fluorescence microscopy

BackgroundDirect sputum smear microscopy is the mainstay of TB diagnosis in most low and middle income countries, and is highly specific for Mycobacterium tuberculosis in such settings. However it is limited by low sensitivity, particularly in HIV co-infected patients. Concentration by centrifugation has been reported to be more sensitive than direct smear preparation, but is only suitable for referral laboratories. Simpler concentration methods that could be applied in peripheral laboratories are urgently needed.MethodsWe evaluated the feasibility of an early prototype ligand-coated magnetic bead technology to concentrate M. tuberculosis prior to detection by LED-based fluorescence microscopy compared with direct Ziehl-Neelsen microscopy and direct and concentrated fluorescence microscopy in a reference laboratory in Kampala, Uganda. Results were compared with MGIT 960 liquid culture and Lowenstein-Jensen culture.ResultsCompared to culture, concentrated FM had significantly higher sensitivity than direct ZN (74.8% and 51.4%), magnetic bead-FM (65.4%) and direct FM (58.9%). The sensitivity of magnetic bead FM was significantly higher than direct ZN (p < 0.001) but not significantly higher than direct FM (p = 0.210). The specificity of magnetic bead FM and concentrated FM was significantly lower than direct ZN (88.6%, 94.3% and 98.9% respectively) and direct FM (99.4%). There was no significant difference in specificity between magnetic bead FM and concentrated FM. Allowing for blinded resolution of discrepant results, the specificity of magnetic bead FM increased to 93.1%. Direct microscopy was simpler than concentrated FM and Magnetic bead FM which both had a similar number of steps.ConclusionThe sensitivity of the early prototype magnetic bead FM was lower than concentrated FM, similar to direct FM, and significantly higher than direct ZN. Both magnetic bead and concentration by centrifugation led to reduced specificity compared with the direct smear methods. Some magnetic bead FM false positive results were not easily explained and should be further investigated. The prototype version of the magnetic bead procedure tested here was of similar complexity to concentration by centrifugation. As such, if the sensitivity of the magnetic bead FM could be improved in future versions of the technology, this may offer a viable alternative to centrifugation.

An evaluation study of the sputum smear concentration technique for the laboratory diagnosis of pulmonary tuberculosis

The microbial diagnosis of Pulmonary Tuberculosis plays a key role in routine treatment and Tuberculosis control Programmes in developing countries. Many patients have presented with signs and symptoms of pulmonary tuberculosis, of which consecutive direct sputum smear microscopy have given negative results for Acid-Fast Bacilli (AFB). Microscopy of smears made directly from sputum has a low sensitivity and there is an urgent need for improved methods. This study was carried out at the Yaounde University Teaching Hospital and is aimed at evaluating the sputum smear concentration technique in the laboratory diagnosis of pulmonary TB. Sputum samples were collected in screw-cap tight containers and evaluated by both the direct and concentrated methods. Microscopy of direct smears of sputum after liquefaction with 5% sodium hypochlorite (NaOCl) solution; and concentration of the organisms by centrifugation were compared and evaluated. Results showed an increase in sensitivity from 18.27% to 25% with a specificity of 90.95%. The tuberculosis prevalence was 25%. 13.33% belongs to the age range 20-40 years and 11.67% to the age range >40 years. The positive predictive value was 73%. We concluded that the use of sodium hypochlorite (NaOCl) in the concentration of acid-fast bacilli (AFB) in sputum significantly improves the laboratory diagnosis of pulmonary tuberculosis. Keywords : Sputum smear concentration, Laboratory diagnosis, Pulmonary tuberculosis

Re-Emergence of Paragonimiasis in Nigeria. A Case Report and Future Challenges.

AIM: Imo State of Nigeria was an endemic area for paragonimiasis from 1964 to 1980. A well planned eradication program was put in place and no case was recorded from 1980 to 2007. In October 2007 the first patient with the disease voluntarily reported at the base hospital at 21A Park Road, Aba Nigeria. This case calls to mind a possible re-emergence of the disease–hence this report to alert health stakeholders to initiate and sustain disease eradication program that will give everlasting solution to this disease problem. METHOD: A healthy looking man reported with chronic cough and haemoptysis at the hospital. Ziehl-Neelsen sputum test was done daily for 3 days for acid-fast bacilli. Direct sputum smear microscopy for eggs of paragonimiasis was done. Blood was examined for differential white blood count and direct X-ray chest films were examined also. RESULTS: Sputum was negative for acid-fast mycobacterium organisms. Sputum showed eggs of P. uterobilateralis. Eosinophil count was 15% of the total white blood count. Chest X-ray film showed abnormal soft shadows in one area of the upper left lung field. The patient was diagnosed to have paragonimiasis. CONCLUSION: Eradication program put in place in the endemic paragonimiasis area of Imo State of Nigeria broke the circle of the disease transmission. When the program implementation was relaxed or non-existent the circle closed–hence the re-emergence. It is wise to report this case hoping that the stakeholders will restart the programme continues and sustain it to ensure lasting eradication. This re-emergence could occur anywhere in the world with similar disease transmitting conditions. A lesson learnt here would be of immense benefit to readers especially to health workers.

Tuberculose ativa em pacientes cirúrgicos com baciloscopia negativa no pré-operatório

To determine the proportion of negative preoperative sputum smear results among patients presenting active TB, as identified through the evaluation of surgical samples. A retrospective study of patients undergoing surgery between 2003 and 2006 at a university hospital and receiving a histopathological diagnosis of active or latent TB. We reviewed patient histories, TB-related clinical aspects, acid-fast bacilli (AFB) test results, type of surgery performed and histopathological findings in surgical samples. We included 43 patients, 27 of whom were male. The mean age was 44 + or - 19 years. Twenty-eight patients had a history of TB (treated appropriately), and 15 reported no history of the disease. The main reason for seeking treatment was recurrent infection, followed by alterations seen in imaging studies. Of the 43 patients, 35 underwent preoperative AFB testing: 32 tested negative, and 3 tested positive. Among those 35 patients, the histopathological diagnosis was active TB in 26 and latent TB in 9. The 8 patients not submitted to preoperative AFB testing were also diagnosed with latent TB. The proportion of active TB in patients with negative sputum smear results was 72% (23/32), whereas that of negative sputum smear results in patients with active TB was 88% (23/26). Only 11.5% (3/26) of the patients had tested positive for AFB. Direct sputum smear microscopy has a very low yield. Many previously treated patients can present negative sputum smear results and yet have active TB. Active TB can be mistaken for secondary infections or for cancer.

A Pilot Study of Short-Duration Sputum Pretreatment Procedures for Optimizing Smear Microscopy for Tuberculosis

BackgroundDirect sputum smear microscopy for tuberculosis (TB) lacks sensitivity for the detection of acid fast bacilli. Sputum pretreatment procedures may enhance sensitivity. We did a pilot study to compare the diagnostic accuracy and incremental yield of two short-duration (<1 hour) sputum pretreatment procedures to optimize direct smears among patients with suspected TB at a referral hospital in India.Methodology/FindingsBlinded laboratory comparison of bleach and universal sediment processing (USP) pretreated centrifuged auramine smears to direct Ziehl-Neelsen (ZN) and direct auramine smears and to solid (Loweinstein-Jensen (LJ)) and liquid (BACTEC 460) culture. 178 pulmonary and extrapulmonary TB suspects were prospectively recruited during a one year period. Thirty six (20.2%) were positive by either solid or liquid culture. Direct ZN smear detected 22 of 36 cases and direct auramine smears detected 26 of 36 cases. Bleach and USP centrifugation detected 24 cases each, providing no incremental yield beyond direct smears. When compared to combined culture, pretreated smears were not more sensitive than direct smears (66.6% vs 61.1 (ZN) or 72.2 (auramine)), and were not more specific (92.3% vs 93.0 (ZN) or 97.2 (auramine).Conclusions/SignificanceShort duration sputum pretreatment with bleach and USP centrifugation did not increase yield as compared to direct sputum smears. Further work is needed to confirm this in a larger study and also determine if longer duration pre-treatment might be effective in optimizing smear microscopy for TB.

Sensitivity of direct versus concentrated sputum smear microscopy in HIV-infected patients suspected of having pulmonary tuberculosis

BackgroundSputum concentration increases the sensitivity of smear microscopy for the diagnosis of tuberculosis (TB), but few studies have investigated this method in human immunodeficiency virus (HIV)-infected individuals.MethodsWe performed a prospective, blinded evaluation of direct and concentrated Ziehl-Neelsen smear microscopy on a single early-morning sputum sample in HIV-infected patients with > 2 weeks of cough hospitalized in Kampala, Uganda. Direct and concentrated smear results were compared with results of Lowenstein-Jensen culture.ResultsOf 279 participants, 170 (61%) had culture-confirmed TB. The sensitivity of direct and concentrated smear microscopy was not significantly different (51% vs. 52%, difference 1%, 95% confidence interval (CI): [-7%, 10%], p = 0.88). However, when results of both direct and concentrated smears were considered together, sensitivity was significantly increased compared with either method alone (64%, 95% CI: [56%, 72%], p < 0.01 for both comparisons) and was similar to that of direct smear results from consecutive (spot and early-morning) specimens (64% vs. 63%, difference 1%, 95% CI: [-6%, 8%], p = 0.85). Among 109 patients with negative cultures, one had a positive direct smear and 12 had positive concentrated smears (specificity 99% vs. 89%, difference 10%, 95% CI: [2%, 18%], p = 0.003). Of these 13 patients, 5 (38%) had improved on TB therapy after two months.ConclusionSputum concentration did not increase the sensitivity of light microscopy for TB diagnosis in this HIV-infected population. Given the resource requirements for sputum concentration, additional studies using maximal blinding, high-quality direct microscopy, and a rigorous gold standard should be conducted before universally recommending this technique.

The clinical value of new diagnostic tools for tuberculosis

Barriers to global tuberculosis (TB) control include multidrug resistance, HIV infection, and weak health systems. Case detection is critical to TB control and is affected by all three of these. Currently, most low- and middle-income countries (LMICs) rely on direct sputum smear microscopy for diagnosis. Modern culture methods and molecular tests, previously considered too complex or too expensive for implementation in LMICs, are now being introduced there in parallel with a global effort to strengthen laboratories. It remains to be seen whether services based on these tools can be made widely accessible to patients. New point-of-care tests for TB are urgently needed but cannot be expected in the near future. In the meantime, diagnostic tools based on optimized smear microscopy, although less sensitive than reference laboratory tests, may be more accessible and have more impact on case finding. It is a matter of urgency that these improved microscopy services be integrated with services based on rapid methods that can identify multidrug-resistant cases.

Haematological Changes in Tuberculosis in Kano, Nigeria

The potential hazard associated with the concentration processes of sputum for acid fast bacilli (AFB) and lack of culture facilities have made it inevitable for many centers which rely on direct sputum smear microscopy to under-diagnose tuberculosis. This is the situation in Kano metropolis where the prevalence rate may be difficult to determine. The aim of this study is to establish a characteristic haematological pattern which could assist in the differential diagnosis of tuberculosis. Routine haematological analysis was carried out in respect of PCV, Hb, WBC (Total and differential counts), erythrocyte sedimentation rate (ESR) and blood film examination in 290 AFB positive patients who attended the General Outpatients Departments of Infectious Diseases Hospital and Aminu Kano Teaching Hospital Kano, between April 2001 and December 2004. Age- and sex-matched healthy controls were evaluated along with the enrolled patients. The highest prevalence rate of infection 90 (31%) occurred in the age groups (21 – 30 years). In patients with pulmonary tuberculosis, the prevalence of mild anemia, raised ESR, leucocytosis, neutrophilia with toxic granulations, thrombocytosis and occasional stickiness of platelets, and monocytosis was higher (P Keywords : Haematology, tuberculosis, Kano. Journal of Medical Laboratory Sciences Vol. 14 (2) 2005: pp. 35-39

Comparison With The Smart Check Recombinant TB Serology Assay And Direct Sputum Microscopy For Acid Fast Bacilli Among Suspected HIV Positive Patients In Northeastern Nigeria

Currently, the Sputum smear microscopy for acid fast bacilli is the corner stone of diagnosis of HIV associated active TB in Nguru, Northeastern Nigeria. This method has low sensitivity and specificity. In this study, we set out to compare the reliability of the Smart Check Recombinant TB rapid test kit with the routine direct sputum microscopy for acid- fast bacilli (AFB). Using Ziehl-Neelsen stained sputum smear microscopy for AFB as the standard, sensitivity and specificity of the Smart Check Recombinant TB rapid test kit was 96.7 % and 82.1 % respectively. These results show that the performance of the Smart Check Recombinant TB rapid test kit was adequate in comparison with direct sputum smear microscopy by sensitivity and specificity for the diagnosis of active TB in HIV infected patients when alternative is just clinical suspicion.

Community-based directly observed treatment shortcourse strategy in pilot districts of Tigray: overview of baseline studies

The burden of tuberculosis is increasing despite the introduction of Directly Observed Treatment Short course (DOTS) strategy which was started in Ethiopia in 1993 GC with its gradual expansion to all parts of the country. Currently it is estimated that more than 70% of the Ethiopian population has access to DOTS coverage. Patients with tuberculosis (TB) have free access to diagnostic and treatment services in all public health institutions. Patients with symptoms suggestive of tuberculosis must be referred from clinics/health posts to health centers and/or hospitals for diagnosis. Health centers can only diagnose smear-positive pulmonary tuberculosis by direct sputum-smear microscopy but they must refer smear-negative pulmonary tuberculosis (PTB) and extra-pulmonary tuberculosis (EPTB) patients to hospitals for further investigation. Hospitals are equipped with x-ray facilities and serve as the only diagnostic units for smear-negative PTB and EPTB. Currently patients take their first 2 months of treatment under the observation of health workers in public health facilities then followed by a monthly visit for medical check up during the remaining 6 months. (excerpt)