Transmission of MERS-coronavirus in household contacts.

BACKGROUND: Strategies to contain the Middle East respiratory syndrome coronavirus (MERS-CoV) depend on knowledge of the rate of human-to-human transmission, including subclinical infections. A lack of serologic tools has hindered targeted studies of transmission. METHODS: We studied 26 index patients with MERS-CoV infection and their 280 household contacts. The median time from the onset of symptoms in index patients to the latest blood sampling in contact patients was 17.5 days (range, 5 to 216; mean, 34.4). Probable cases of secondary transmission were identified on the basis of reactivity in two reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assays with independent RNA extraction from throat swabs or reactivity on enzyme-linked immunosorbent assay against MERS-CoV S1 antigen, supported by reactivity on recombinant S-protein immunofluorescence and demonstration of neutralization of more than 50% of the infectious virus seed dose on plaque-reduction neutralization testing. RESULTS: Among the 280 household contacts of the 26 index patients, there were 12 probable cases of secondary transmission (4%; 95% confidence interval, 2 to 7). Of these cases, 7 were identified by means of RT-PCR, all in samples obtained within 14 days after the onset of symptoms in index patients, and 5 were identified by means of serologic analysis, all in samples obtained 13 days or more after symptom onset in index patients. Probable cases of secondary transmission occurred in 6 of 26 clusters (23%). Serologic results in contacts who were sampled 13 days or more after exposure were similar to overall study results for combined RT-PCR and serologic testing. CONCLUSIONS: The rate of secondary transmission among household contacts of patients with MERS-CoV infection has been approximately 5%. Our data provide insight into the rate of subclinical transmission of MERS-CoV in the home.

Viral Shedding and Antibody Response in 37 Patients With Middle East Respiratory Syndrome Coronavirus Infection.

BACKGROUND: The Middle East respiratory syndrome (MERS) coronavirus causes isolated cases and outbreaks of severe respiratory disease. Essential features of the natural history of disease are poorly understood. METHODS: We studied 37 adult patients infected with MERS coronavirus for viral load in the lower and upper respiratory tracts (LRT and URT, respectively), blood, stool, and urine. Antibodies and serum neutralizing activities were determined over the course of disease. RESULTS: One hundred ninety-nine LRT samples collected during the 3 weeks following diagnosis yielded virus RNA in 93% of tests. Average (maximum) viral loads were 5 × 10(6) (6 × 10(10)) copies/mL. Viral loads (positive detection frequencies) in 84 URT samples were 1.9 × 10(4) copies/mL (47.6%). Thirty-three percent of all 108 serum samples tested yielded viral RNA. Only 14.6% of stool and 2.4% of urine samples yielded viral RNA. All seroconversions occurred during the first 2 weeks after diagnosis, which corresponds to the second and third week after symptom onset. Immunoglobulin M detection provided no advantage in sensitivity over immunoglobulin G (IgG) detection. All surviving patients, but only slightly more than half of all fatal cases, produced IgG and neutralizing antibodies. The levels of IgG and neutralizing antibodies were weakly and inversely correlated with LRT viral loads. Presence of antibodies did not lead to the elimination of virus from LRT. CONCLUSIONS: The timing and intensity of respiratory viral shedding in patients with MERS closely matches that of those with severe acute respiratory syndrome. Blood viral RNA does not seem to be infectious. Extrapulmonary loci of virus replication seem possible. Neutralizing antibodies do not suffice to clear the infection.

An observational, laboratory-based study of outbreaks of middle East respiratory syndrome coronavirus in Jeddah and Riyadh, kingdom of Saudi Arabia, 2014.

BACKGROUND: In spring 2014, a sudden rise in the number of notified Middle East respiratory syndrome coronavirus (MERS-CoV) infections occurred across Saudi Arabia with a focus in Jeddah. Hypotheses to explain the outbreak pattern include increased surveillance, increased zoonotic transmission, nosocomial transmission, and changes in viral transmissibility, as well as diagnostic laboratory artifacts. METHODS: Diagnostic results from Jeddah Regional Laboratory were analyzed. Viruses from the Jeddah outbreak and viruses occurring during the same time in Riyadh, Al-Kharj, and Madinah were fully or partially sequenced. A set of 4 single-nucleotide polymorphisms distinctive to the Jeddah outbreak were determined from additional viruses. Viruses from Riyadh and Jeddah were isolated and studied in cell culture. RESULTS: Up to 481 samples were received per day for reverse transcription polymerase chain reaction (RT-PCR) testing. A laboratory proficiency assessment suggested positive and negative results to be reliable. Forty-nine percent of 168 positive-testing samples during the Jeddah outbreak stemmed from King Fahd Hospital. All viruses from Jeddah were monophyletic and similar, whereas viruses from Riyadh were paraphyletic and diverse. A hospital-associated transmission cluster, to which cases in Indiana (United States) and the Netherlands belonged, was discovered in Riyadh. One Jeddah-type virus was found in Riyadh, with matching travel history to Jeddah. Virus isolates representing outbreaks in Jeddah and Riyadh were not different from MERS-CoV EMC/2012 in replication, escape of interferon response, or serum neutralization. CONCLUSIONS: Virus shedding and virus functions did not change significantly during the outbreak in Jeddah. These results suggest the outbreaks to have been caused by biologically unchanged viruses in connection with nosocomial transmission.

Infectious Middle East Respiratory Syndrome Coronavirus Excretion and Serotype Variability Based on Live Virus Isolates from Patients in Saudi Arabia.

The newly emerged Middle East respiratory syndrome coronavirus (MERS-CoV) has infected at least 1,082 people, including 439 fatalities. So far, no empirical virus isolation study has been done to elucidate infectious virus secretion or serotype variability. Here, we used 51 respiratory samples from 32 patients with confirmed MERS-CoV infection for virus isolation in Vero B4 and Caco-2 cells. We found Caco-2 cells to significantly enhance isolation success over routinely used Vero cells. Isolation success correlated with viral RNA concentration and time after diagnosis as well as with the amount of IgA antibodies secreted in respiratory samples used for isolation. Results from plaque reduction neutralization assays using a representative range of serum samples and virus isolates suggested that all circulating human MERS-CoV strains represent one single serotype. The choice of prototype strain is not likely to influence the success of candidate MERS-CoV vaccines. However, vaccine formulations should be evaluated for their potential to induce IgA.

High dose intravenous colistin methanesulfonate therapy is associated with high rates of nephrotoxicity; a prospective cohort study from Saudi Arabia.

BACKGROUND: Nephrotoxicity is an important adverse effect of colistin methanesulfonate (CMS) therapy. No data exist on rates and risk factors for colistin-related nephrotoxicity in Saudi Arabia (SA). We conducted a prospective cohort study to identify rates and risk factors for CMS nephrotoxicity in our patient population. METHODS: We prospectively included adult patients who received ≥48 hours of intravenous CMS therapy. Pregnant patients and those on renal replacement were excluded. Patients received 9 million units (mU) loading dose followed by 3 mU 8 hourly. In renal impairment, CMS dosing was adjusted according to calculated creatinine clearance (CrCl). Nephrotoxicity was defined as per RIFLE criteria (Risk, Injury, Failure, Loss and End-stage renal disease). Statistical analysis was performed using SPSS version 20.0 (IBM, Armonk, New York, USA). The study was approved by the institution's Research Ethics Committee. RESULTS: A total of 67 patients were included in the study. Mean (±standard deviation) age was 57.5 (±24.0) years, Charlson Co-morbidity Score 2.88 (±2.39), CrCl 133.60 (±92.54) mL/min and serum albumin 28.65 (±4.45) g/L. Mean CMS dose was 0.11 (±0.04) mU/kg/day and mean total CMS dose received was 101.21 (±47.37) mU. Fifty-one (76.1%) patients developed RIFLE-defined nephrotoxicity. Mean total CMS dose and duration of therapy before onset of nephrotoxicity were 66.71 (±43.45) mU and 8.70 (±6.70) days, respectively. In bivariate analysis, patients with nephrotoxicity were significantly older (P 0.013) and had lower baseline serum albumin (P 0.008). Multivariate logistic regression identified serum albumin [odds ratio (OR) 0.72; 95% confidence interval (CI) 0.57-0.93; P 0.010] and intensive care admission (OR 16.38; 95% CI 1.37-195.55; P 0.027) as independent risk factors for CMS nephrotoxicity. CONCLUSIONS: High dose intravenous CMS therapy is associated with high rates of nephrotoxicity in SA. Independent risk factors for colistin nephrotoxicity were baseline hypoalbuminemia and intensive care admission.

Respiratory tract samples, viral load, and genome fraction yield in patients with Middle East respiratory syndrome.

BACKGROUND: Analysis of clinical samples from patients with new viral infections is critical to confirm the diagnosis, to specify the viral load, and to sequence data necessary for characterizing the viral kinetics, transmission, and evolution. We analyzed samples from 112 patients infected with the recently discovered Middle East respiratory syndrome coronavirus (MERS-CoV). METHODS: Respiratory tract samples from cases of MERS-CoV infection confirmed by polymerase chain reaction (PCR) were investigated to determine the MERS-CoV load and fraction of the MERS-CoV genome. These values were analyzed to determine associations with clinical sample type. RESULTS: Samples from 112 individuals in which MERS-CoV was detected by PCR were analyzed, of which 13 were sputum samples, 64 were nasopharyngeal swab specimens, 30 were tracheal aspirates, and 3 were bronchoalveolar lavage specimens; 2 samples were of unknown origin. Tracheal aspirates yielded significantly higher MERS-CoV loads, compared with nasopharyngeal swab specimens (P = .005) and sputum specimens (P = .0001). Tracheal aspirates had viral loads similar to those in bronchoalveolar lavage samples (P = .3079). Bronchoalveolar lavage samples and tracheal aspirates had significantly higher genome fraction than nasopharyngeal swab specimens (P = .0095 and P = .0002, respectively) and sputum samples (P = .0009 and P = .0001, respectively). The genome yield from tracheal aspirates and bronchoalveolar lavage samples were similar (P = .1174). CONCLUSIONS: Lower respiratory tract samples yield significantly higher MERS-CoV loads and genome fractions than upper respiratory tract samples.

Transmission and evolution of the Middle East respiratory syndrome coronavirus in Saudi Arabia: a descriptive genomic study.

BACKGROUND: Since June, 2012, Middle East respiratory syndrome coronavirus (MERS-CoV) has, worldwide, caused 104 infections in people including 49 deaths, with 82 cases and 41 deaths reported from Saudi Arabia. In addition to confirming diagnosis, we generated the MERS-CoV genomic sequences obtained directly from patient samples to provide important information on MERS-CoV transmission, evolution, and origin. METHODS: Full genome deep sequencing was done on nucleic acid extracted directly from PCR-confirmed clinical samples. Viral genomes were obtained from 21 MERS cases of which 13 had 100%, four 85-95%, and four 30-50% genome coverage. Phylogenetic analysis of the 21 sequences, combined with nine published MERS-CoV genomes, was done. FINDINGS: Three distinct MERS-CoV genotypes were identified in Riyadh. Phylogeographic analyses suggest the MERS-CoV zoonotic reservoir is geographically disperse. Selection analysis of the MERS-CoV genomes reveals the expected accumulation of genetic diversity including changes in the S protein. The genetic diversity in the Al-Hasa cluster suggests that the hospital outbreak might have had more than one virus introduction. INTERPRETATION: We present the largest number of MERS-CoV genomes (21) described so far. MERS-CoV full genome sequences provide greater detail in tracking transmission. Multiple introductions of MERS-CoV are identified and suggest lower R0 values. Transmission within Saudi Arabia is consistent with either movement of an animal reservoir, animal products, or movement of infected people. Further definition of the exposures responsible for the sporadic introductions of MERS-CoV into human populations is urgently needed. FUNDING: Saudi Arabian Ministry of Health, Wellcome Trust, European Community, and National Institute of Health Research University College London Hospitals Biomedical Research Centre.

COVID-19 vaccine breakthrough infection among health care workers at MODHS hospitals in Saudi Arabia: A multicenter study.

BACKGROUND: We investigated the clinical manifestation and severity of COVID-19 infection represented as a composite outcome (hospital or ICU admission, or in-hospital death) among infected fully vaccinated HCWs, the RT-PCR test Ct value (Cycle Threshold) of positive fully vaccinated HCWs, and we measure the interval from the second vaccine to acquiring the infection. METHODS: A multicenter retrospective cohort study was conducted in different regions at (16) Ministry of Defense Health Services (MODHS) hospitals. Data were restricted to fully vaccinated (minimum of 2 doses) HCWs who had a confirmed positive PCR test and employed in MODHS hospitals from August 2021 to March 2022. RESULTS: A total of 45862 HCWs were vaccinated as of Aug 2021. Of these 1253 participants met the selection criteria and were included in the study. The average age of infected HCWs was 35.27 years (SD = ± 8.10) of which 57% were females. The HCWs were employed as doctors (24%), nurses (33%), and other (43%). The most administered vaccine type was mRNA (44%) followed by Adenovirus Viral Vector (39%) and mixed vaccine (17%). The incidence of COVID-19 vaccine breakthrough (BT) infection among HCWs was observed at 2.73% (m-RNA 3.19%, Viral Vector 2.83% and mixed 1.87%). CONCLUSION: the overall COVID-19 (BT) infection incidence proportion was (2.73%), with the Mixed vaccine group showing the lowest (BT) incidence proportion (1.87%). The most commonly reported symptoms among (BT) infections were cough (51%), sore throat (51%), fever (47%), headache (31%), and runny nose (23%), with overall (6%) asymptomatic (BT) infections. We had (1%) hospital admissions, Zero ICU admission, and Zero deaths. our finding may indicate that infection affecting fully vaccinated patients were less severe and mostly affected the upper respiratory tract.

Self-reported long COVID-19 symptoms are rare among vaccinated healthcare workers.

INTRODUCTION: COVID-19 pandemic adversely affected healthcare workers (HCWs). Here, we evaluate the occurence of long-COVID-19 symtoms among HCWs. METHODS: This is a questionnaire-based study of HCWs who had COVID-19 in two medical centers in Saudi Arabia and were mostly vaccinated. RESULTS: The study included 243 HCWs with a mean age (+ SD) of 36.1 (+ 7.6) years. Of them, 223 (91.8%) had three doses of COVID-19 vaccine, 12 (4.9%) had four doses, and 5 (2.1%) had two doses. The most common symptoms at the start of the illness were cough (180, 74.1%), shortness of breath (124, 51%), muscle ache (117, 48.1%), headache (113, 46.5%), sore throat (111, 45.7%), diarrhea (109, 44.9%) and loss of taste (108, 44.4%). Symptoms lasted for< one week in 117 (48.1%),> one week and< 1 month in 89 (36.6%),> 2 months and< 3 months in 9 (3.7%), and> 3 months in 15 (6.2%). The main symptoms present> 3 months were hair loss (8, 3.3%), cough (5, 2.1%), and diarrhea (5, 2.1%). A binomial regression analysis showed no relationship between persistence of symptoms for> 3 months and other demographic or clinical symptoms characteristics. CONCLUSION: The study showed a low rate of the occurence of long-COVID> 3 months during the Omicron-wave among mostly vaccinated HCWs with no significant comorbidities. Furhter studies are needed to examine the effect of different vaccines on long-COVID-19 among HCWs.

COVID-19 vaccine had a significant positive impact on patients with SARS-COV-2 during the third (Omicron) wave in Saudi Arabia.

INTRODUCTION: The third (Omicron) wave had caused significant increase in the number of COVID-19 cases around the globe. The severity of the disease dependeds on the extent of the vaccination status. METHODS: This is a retrospective study of infected COVID-19 patients during the third (Omicron) wave in a hospital in Saudi Arabia. RESULTS: A total of 400 patients were included with 220 (55 %) males and 180 (45 %) females, and a mean age (+/- SD) of 36.34 + 16.47 years. The most common presenting symptoms were: sore throat 159 (39.8 %), cough 158 (39.5 %), fever 132 (33 %), headache 122 (30.5 %), and muscle ache 124 (31%). There was no difference in underlying conditions, signs and symptoms between males and females apart from the occurrence of sore throat with an OR of 2.014 (95 % CI: 1.103-3.677, P = 0.023) and need of hospitalization OR 2.457 (95 % CI: 1.168-5.167, P value =.018) in a binary logistic regression comparison. The need for hospitalization was inversely related to the number of COVID-19 vaccination doses. The rate of admission was 8 (72.7 %), 34 (12 %), 4 (5.4 %) for one, two, and three doses of COVID-19 vaccine, respectively (P < 0.0001). Of all the patients, 14 (3.5 %) and 8 (2 %) required intensive care (ICU) admission and mechanical ventilation, respectively. The median Ct-value of SARS-CoV-2 was higher in those who had 2 or 3 doses compared to those who had one dose of the COVID-19 vaccine, but the difference did not reach statistical significance. None of the included patients died during the study period. CONCLUSION: Omicron variant symptoms among infected patients are generally milder compared to other variants. Prior COVID-19 vaccination may limit disease severity and need for hospitalization.

Seroprevalence of Alkhurma and other hemorrhagic fever viruses, Saudi Arabia.

A 2009 deployment of military units from several Saudi Arabian provinces to Jazan Province, Saudi Arabia, enabled us to evaluate exposure to Alkhurma, Crimean-Congo, dengue, and Rift Valley hemorrhagic fever viruses. Seroprevalence to all viruses was low; however, Alkhurma virus seroprevalence was higher (1.3%) and less geographically restricted than previously thought.

Abdominal tuberculosis in a tertiary care centre in Saudi Arabia.

OBJECTIVES: Abdominal tuberculosis (ATB) is the second most common type of extra-pulmonary tuberculosis. Though it does not usually pose a significant risk of infectivity, ATB can go unidentified and progress to disseminated infection. The aim of this study is to highlight the incidence and outcome of this infection in a tertiary care centre in the Kingdom of Saudi Arabia (KSA). METHODS: In this retrospective study, we included all ATB patients admitted to our centre between January 1 st, 2010 and December 31, 2018. A total of 42 patients with a median age of 49 (range 18-83 years, 78.6% males) were identified. RESULTS: The most common presentation was abdominal pain, weight loss, and abdominal distension. All the patients were HIV negative; however, 50% had a comorbid condition, mainly diabetes mellitus, chronic renal failure, and liver cirrhosis. Tuberculous peritonitis was the predominant type of ATB. Suspicious and potentially malignant abdominal masses appeared on the abdominal CT scans of six patients. This suggest that TB should be excluded in patients from endemic area presenting with abdominal masses. All patients received standard anti-tuberculous medication for an average duration of 7.4 months. The outcome was excellent with 88%% achieving complete response. Adjunctive corticosteroids were not used, and none of the patients had a surgical complication. CONCLUSION: The diagnosis of ATB is challenging. It can mimic inflammatory bowel disease in young populations and malignancy in middle-aged and elderly population. For this reason, a high index of suspicion with prompt treatment is required to improve the prognosis and prevent complications.

Antimicrobial resistance trends of non-fermenter Gram negative bacteria in Saudi Arabia: A six-year national study.

BACKGROUND: Antimicrobial resistance (AMR) of non-fermenting Gram-negative bacteria (NFGNB) is increasingly recognized as urgent healthcare threat. Trend data on AMR of NFGNB in Saudi Arabia are either old or limited. The objective was to estimate the prevalence and resistance trends of isolated NFGNB in Saudi Arabia. METHODS: A retrospective multicenter study involving seven tertiary care hospitals in Saudi Arabia was conducted between 2011 and 2016. Susceptibility testing for non-duplicate isolates was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines in College of American Pathologists accredited diagnostic microbiology laboratories in the participating hospitals. RESULTS: Out of 461,274 isolates, 100,132 (21.7%) were NFGNB which represented 30% of gram-negative pathogens. Pseudomonas aeruginosa was the most common (73.6%), followed by Acinetobacter baumannii (21.0%) and Stenotrophomonas maltophilia (5.3%). Resistance trends of P. aeruginosa were increasing for aztreonam (absolute increase during the study was 17.3%), imipenem (12.3%), and meropenem (11.6%). A. baumannii was fully resistant to several beta lactam drugs, and resistance trends were increasing for potential treatments such as tigecycline (25.1%) and tobramycin (15.5%). S. maltophilia was >90% resistant to trimethoprim/ sulfamethoxazole and ciprofloxacin by the end of the study. CONCLUSION: We are reporting high and/or increasing resistance of NFGNB to common treatment options. The current findings call for urgent actions to combat the increasing resistance of NFGNB. Large scale sharing of AMR data collected at different hospitals with the Saudi AMR committee would be critical to set priorities and monitor progress.

Safety and Reactogenicity of the ChAdOx1 (AZD1222) COVID-19 Vaccine in Saudi Arabia.

INTRODUCTION: The Kingdom of Saudi Arabia was one of the first countries to implement a COVID-19 vaccination program. This study estimated the safety and reactogenicity of the ChAdOx1-S vaccine after the first dose administered to adults. METHODS: This cross-sectional study included 1592 randomly selected vaccinees from April to May 2021. A questionnaire was delivered to the vaccinees via phone calls 7 and 21 days after the first vaccine dose. RESULTS: Of the 1592 vaccinees who had the first dose, the mean age was 37.4 (± 9.6) years and 81% were males. Of all the vaccinees, 553 (34.7%) reported an adverse reaction on the first telephone call. The most common symptoms were: pain at the site of injection (485, 30.5%), musculoskeletal symptoms (438, 27.5%), skin rash (307, 19.2%), gastrointestinal symptoms (379, 23.8%) and fever (498, 31.3%). Men were more likely to report fever (76.9% vs. 23.1%; P = 0.005), skin rash (81.1% vs. 18.9%, P = 0.005) and pain at the injection site (77.3% vs. 22.7%, P < 0.0001). Post-vaccine COVID-19 infection was 0.5% and there were no hospitalizations. CONCLUSION: This study observed no major side effects of the ChAdOx1-S vaccine and no reported breakthrough infection during the observation period.

Miliary tuberculosis presenting as bilateral superficial femoral artery mycotic aneurysm in an immunocompetent patient.

Mycotic tuberculous aneurysm is extremely rare. The aorta is the main affected artery however; iliac and less commonly femoral arteries can also be affected. In 75% of the cases a contagious focus leads to infection through erosion of the vessel wall; on the other hand direct seeding of the blood vessel wall via the vasa vasorum may occur in 25%. In a large number of patients it may be a manifestation of miliary tuberculosis. In this case report we describe an immunocompetent patient who presented with bilateral superficial femoral artery aneurysms, followed by bilateral testicular swellings and inferior mesenteric artery aneurysm, as a presentation of military tuberculosis. Early diagnosis of such patients is essential for initiation of both medical and surgical treatment in order to avoid catastrophic outcome of rupture and bleeding.

Clinical respiratory infections and pneumonia during the Hajj pilgrimage: A systematic review.

BACKGROUND: The Islamic Hajj pilgrimage to Mecca is one of the world's largest annual mass gatherings. Inevitable overcrowding during the pilgrims' stay greatly increases the risk of acquiring and spreading infectious diseases, especially respiratory diseases. METHOD: The MEDLINE/PubMed and Scopus databases were searched for all relevant papers published prior to February 2018 that evaluated the prevalence of clinical symptoms of respiratory infections, including pneumonia, among Hajj pilgrims, as well as their influenza and pneumococcal vaccination status. RESULTS: A total of 61 papers were included in the review. Both cohort- and hospital-based studies provide complementary data, and both are therefore necessary to provide a complete picture of the total burden of respiratory diseases during the Hajj. Respiratory symptoms have been common among Hajj pilgrims over the last 15 years. In cohorts of pilgrims, cough ranged from 1.9% to 91.5%. However, the prevalence rates of the most common symptoms (cough, sore throat, and subjective fever) of influenza-like illness (ILI) varied widely across the included studies. These studies have shown variable results, with overall rates of ILI ranging from 8% to 78.2%. These differences might result from differences in study design, study period, and rates of vaccination against seasonal influenza that ranged from 1.1% to 100% among study participants. Moreover, the definition of ILI was inconsistent across studies. In hospitalized Hajj pilgrims, the prevalence of pneumonia, that remains a major concern in critically ill patients, ranged from 0.2% to 54.8%. CONCLUSIONS: Large multinational follow-up studies are recommended for clinic-based syndromic surveillance, in conjunction with microbiological surveillance. Matched cohorts ensure better comparability across studies. However, study design and data collection procedures should be standardized to facilitate reporting and to achieve comparability between studies. Furthermore, the definition of ILI, and of most common symptoms used to define respiratory infections (e.g., upper respiratory tract infection), need to be precisely defined and consistently used. Future studies need to address potential effect of influenza and pneumococcal vaccine in the context of the Hajj pilgrimage.

Isolation and deisolation of patients admitted with presumptive pulmonary tuberculosis. Can it be shortened?

OBJECTIVES: To determine the ideal number of sputum acid-fast bacilli (AFB) smears and polymerase chain reaction (PCR) required for discontinuing TB isolation among patients with suspected pulmonary TB.  Methods: This was a single-center, record-based retrospective study of all admitted patients diagnosed with culture-proven pulmonary TB between 2010 and 2018. The study was conducted at Prince Sultan Military Medical City (PSMMC) in Riyadh, Saudi Arabia, a large tertiary care center consisting of 1,200 beds. Data were obtained from our TB notification records. Patients with smear-positive TB were investigated. Only the first 3 sputum smears for AFB were included in the analysis. The  PCR results for Mycobacterium tuberculosis (MTB) were also included in the study. The incremental yield of the second and third smears was assessed.  Results: Overall, 240 patients were MTB-culture positive. A total of 126 (52.5%) patients were smear and culture positive, whereas 114 were culture positive but smear negative. Of 126 patients who were AFB smear positive, 98 (77.8%) were detected in the first specimen, 13 (10.3%) in the second specimen, and only 9 (7.1%) in the third specimen. Polymerase chain reaction for MTB was positive in 122 (96.8%) smear-positive patients. Four patients did not undergo a PCR test.  Conclusion:  A single Xpert MTB/resistance to rifampicin test detected all smear-positive patients, whereas the third smear did not significantly contribute to MTB isolation.