Heterogeneous vancomycin-intermediate among methicillin resistant Staphylococcus aureus.

BACKGROUND: Hetero-resistance vancomycin intermediate Staphylococcus aureus (hVISA) is phenotype, which on in-vitro susceptibility test is vancomycin susceptible (VSSA) but has a minority population of vancomycin intermediate (VISA). hVISA is responsible for vancomycin treatment failure. Population Analysis Profile- Area under Curve (PAP-AUC) is a test for detection of hVISA; however, this test is unsuitable for clinical microbiology laboratory. Tests, such as Brain Heart Infusion Agar with 6 µg/ml vancomycin (BHIA6V), E test and Macromethod E Test (MET) are available; however reported to have variable results. METHODS: 58 clinical isolates of Methicillin resistant S aureus (MRSA) having MIC of vancomycin more than 1 µg/ml by E test and agar dilution were analyzed by PAP-AUC, BHIA6V and MET. RESULT: The prevalence of hVISA was 6.9%. hVISA isolates were having vancomycin E test MIC >2 µg/ml. Sensitivity of BHIA6V, MET and E test with MIC >2 µg/ml were 0.75, 0.67 and 1.0 respectively; however, positive predictive values (PPV) were 0.43, 0.4 and 0.27 respectively with PAP-AUC. PAP-AUC ratio correlated with MIC by E test and MET. CONCLUSIONS: There is need for screening MRSA isolates showing in-vitro vancomycin susceptibility ≤2 µg/ml by agar dilution method for detection of hVISA. PAP-AUC test is unsuitable for routine laboratory testing. BHIA6V, MET and E test can be used for screening, however have low PPV.

Detection of glycopeptide resistance genes in enterococci by multiplex PCR.

BACKGROUND: Vancomycin Resistant Enterococci (VRE) are a major cause of nosocomial infections. There are various phenotypic and genotypic methods of detection of glycopeptide resistance in enterococci. This study utilizes multiplex PCR for reliable detection of various glycopeptides resistance genes in VRE. METHOD: This study was conducted to detect and to assess the prevalence of vancomycin resistance among enterococci isolates. From October 2011 to June 2013, a total of 96 non-repetitive isolates of enterococci from various clinical samples were analyzed. VRE were identified by Kirby Bauer disc diffusion method with Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) of all isolates for vancomycin and teicoplanin was determined by E-test. Multiplex PCR was carried out for all enterococci isolates using six sets of primers. RESULTS: Out of 96 isolates, 14 (14.6%) were found to be resistant to vancomycin by vancomycin E-test method (MIC ≥32 µg/ml). Out of these 14 isolates, 13 were also resistant to teicoplanin (MIC ≥16 µg/ml). VanA gene was detected in all the 14 isolates by Multiplex PCR. One of the PCR amplicons was sent for sequencing and the sequence received was submitted in the GenBank (GenBank accession no. KF181100). CONCLUSION: Prevalence of VRE in this study was 14.6%. Multiplex PCR is a robust, sensitive and specific technique, which can be used for rapid detection of various glycopeptide resistance genes. Rapid identification of patients infected or colonized with VRE is essential for implementation of appropriate control measures to prevent their spread.

Emergence of multidrug resistant enterococci at a tertiary care centre.

BACKGROUND: Enterococci have assumed great clinical importance because of their increasing resistance to various antimicrobial agents. Thus, knowledge about the antibiogram of these multidrug resistant isolates is of utmost importance in formulating an effective antibiotic policy to treat these infections and reducing the morbidity and mortality. Aim of this study was to assess the antimicrobial resistance pattern of enterococci and determine the prevalence of multidrug resistance among them. METHODS: This cross sectional study was carried out from August 2011 to February 2014, in which 200 non-repetitive clinical isolates of enterococci were included. Antimicrobial susceptibility testing was done by disc diffusion method. Minimum inhibitory concentration (MIC) of gentamicin, streptomycin, vancomycin, teicoplanin and linezolid was determined by E-test method. RESULTS: The prevalence of multidrug resistance among enterococcal isolates was found to be 63%. Varying levels of resistance was seen to various antibiotics. Most of the isolates were resistant to penicillin (95%), ampicillin (95%) and cotrimoxazole (90%). High level aminoglycoside resistance (HLAR) and glycopeptide resistance was seen in 39% and 14% isolates respectively. Only 4 isolates (2%) were found to be resistant to linezolid. CONCLUSION: The prevalence of multidrug resistance among enterococci was found to be 63%, the resistance being more common in Enterococcus faecium as compared to Enterococcus faecalis. The study highlights the emergence and increased prevalence of multidrug resistant enterococci which pose a serious therapeutic challenge.

In vitro vancomycin susceptibility amongst methicillin resistant Staphylococcus aureus.

BACKGROUND: Vancomycin is drug of choice for treatment of Methicillin Resistant Staphylococcus aureus (MRSA) infections. S. aureus with reduced vancomycin susceptibility (SA-RVS) is on rise. Current guidelines of detection of SA-RVS are based on MIC (Minimum Inhibitory Concentration) by broth or agar dilution methods. Vancomycin MIC by E test (Epsilometer Test) is an alternative. A study was undertaken to know the prevalence of SA-RVS and compare vancomycin MIC by agar dilution and E test. METHODS: A prospective study was undertaken at tertiary care hospital; 232 clinical MRSA isolates were included. Vancomycin MIC was undertaken by agar dilution method and E test. RESULTS: All isolates were sensitive to Linezolid. Two MRSA isolates had vancomycin MIC ≥4 µg/ml; vancomycin MIC50 and MIC90 of MRSA isolates was 0.5 and 0.2 µg/ml respectively by agar dilution method. There was agreement over 93.5% isolates in vancomycin susceptibility by agar dilution and E test. E test had sensitivity and positive predictive value of 1.0 (CI - 0.34-1.0) and 0.5 (CI - 0.17-0.83) respectively compare to agar dilution method. CONCLUSIONS: MRSA isolates continues to be susceptible to vancomycin and Linezolid. E test was found equally suitable in initial screening for vancomycin susceptibility. Due to geographic variation in prevalence, there is need of ongoing surveillance of SA-RVC.

Red Cell Alloantibodies in Multiple Transfused Thalassaemia Patients.

BACKGROUND: Thalassaemia major patients require lifelong transfusion support due to which they are prone for alloimmunization to foreign RBCs. Alloimmunization can be prevented by extended phenotype match blood transfusion. The study was conducted to know the extent of problem of alloimmunization and to find important red cell antibodies in thalassaemia patients. METHODS: A cross-sectional study was conducted. A total of 32 thalassaemia patients were enrolled. The specimen was subjected to red cell alloantibody and autoantibody by column gel agglutination technique. R 1 (w) R 1 , R 2 R 2 , rr (papaine and non papain) and 11 cell panel reagent cells were used in screening and identification of alloantibodies respectively. RESULT: Six (18.8 %) subjects were alloimmunized. All alloimmunized subjects were recipient of more than 20 units of transfusion. Total seven clinically significant alloantibodies were identified. Anti E and anti c were commonest antibodies in four (12.5%) patients. CONCLUSION: Red cell alloimmunization is an important risk in thalassaemia patient. 71.4% of alloantibodies were anti E and anti c type. Extended phenotype match blood transfusion for Rh-c and Rh-E antigens or level 2 antigen matching stringency needs to be explored in preventing alloimmunization in thalassaemia patients.

Frozen Red Blood Cells in Transfusion.

Red blood cells (RBCs) can be cryopreserved with shelf life of 10 years. However, shelf life of deglycerolized RBCs in conventional open system is just 24 hours, resulting in sporadic use of Frozen RBC (FS-RBC). Recently Naval Blood Research Laboratory (NBRL) method using ACP 215 (ACP(™) 215 Haemonetics Cell Processing System) has been introduced, where shelf life of deglycerolized RBC is 14 days. FS-RBC unit is prepared from single blood donation, which needs to be glycerolized and deglycerolized. NBRL method using ACP 215 in FS-RBC is described. Deglycerolized unit weighed between 325-350 gm with haemoglobin of 15-18 gm/dl and freeze- thaw- wash RBC recovery of 87%. Transfusion of deglycerolized RBC offered advantages such as elimination of need of crossmatching in emergent situations and reduction of transfusion reactions. FS-RBC by NBRL method using ACP 215 has advantages such as long shelf life, meeting unexpected high blood demand in mass casualties situations or availability of rare blood group requirement of individual patient. FS-RBC can be a potential candidate for Indian Armed Forces Blood programme for uninterrupted blood supply during peace and war.

Seroprevalence of Cytomegalovirus among Voluntary Blood Donors.

BACKGROUND: Primary cytomegalovirus (CMV) infection in immunocompetent host is self limiting infection, leading to latency of virus. However congenital CMV and CMV infections in immunocompromised patients are associated with high morbidity and mortality. Transfusion transmitted-cytomegalovirus (TT-CMV) infection in low birth weight neonate and immunocompromised transfusion recipients is being increasingly reported. Studies recommended transfusion of CMV free or CMV safe blood in prevention of TT-CMV. In this background, the study was undertaken to assess the CMV seroprevalence in blood donor. METHODS: A prospective study was conducted in which 431 voluntary blood donors were screened for CMV IgG and IgM by EIA (Enzyme Immuno Assay). RESULT: A total of 379 (87.9 %) voluntary blood donors were seropositive for CMV IgG. There was no statistical difference of CMV seropositivity and age. Further, seven (1.6%) subjects were both CMV IgM and IgG seropositive. CONCLUSION: High seroprevalence of CMV in our donor population is a threat to the blood safety. Strategies in reducing the risk of TT- CMV are discussed. Use of prestorage leucodepleted 'CMV safe' blood components along with judicious use of blood is recommended in prevention of TT-CMV in high risk recipients.

Prevalence of Human T Cell Leukaemia Virus amongst Blood Donors.

BACKGROUND: Human T cell leukaemia virus (HTLV) I/II are retroviruses implicated in transfusion transmitted infection. Present study was undertaken to assess seroprevalence of HTLV in voluntary blood donors along with pattern of blood utilisation. METHODS: A total of 258 healthy blood donors who were free from infectious markers in transfusion as per current transfusion guidelines were enrolled. They were screened for HTLV-I/II antibodies by commercially available enzyme immuno assay (EIA) and their blood utilisation data was analysed. RESULT: Five (1.9%) donors were found seropositive for HTLV-I/II of which 1.2 % were first time and 0.9% were repeat donors. Blood utilisation data revealed 20.9% and 38.8% units were utilised within 5 and 6-14 days of collection respectively. 45.9% recipients were transfused with single blood unit. 42.9% recipients were immunosuppressed due to underlying disease. CONCLUSION: The high prevalence of HTLV in blood donors, coupled with single unit transfusion, use of fresh blood, non availability of acellular blood products and immunosuppression in recipients can lead to significant transfusion transmitted HTLV infection. We suggest judicious use of blood products and screening of blood donors in prevention of transfusion transmitted HTLV-I/II.

Hepatitis B Immunisation in Health Care Workers.

BACKGROUND: Hepatitis B virus (HBV) infection is an important occupational risk in health care workers (HCW). In spite of HBV vaccine availability in Armed Forces, the high prevalence of HBV infection in HCW continues to be a problem. The study was undertaken to study the HBV vaccine-compliance among HCW. METHODS: A cross-sectional study was conducted at a tertiary care hospital. HCW were requested to fill up the pre set questionnaire to assess the HBV vaccination coverage. RESULT: Amongst 254 HCW, only 57.7% were vaccinated against HBV. The vaccine compliance was lowest among housekeeping professionals. The mean age at vaccination was high (30.5 years). Amongst the vaccine non-compliant subjects, 34.3% were above 30 years of age. 32.2% HCW completed primary vaccination after spending more than 10 years in the profession. Accessibility of HBV vaccine, knowledge and perception of HBV risk were important factors in vaccine non-compliance. CONCLUSION: Due to low and delayed HBV vaccine-compliance, HCW continue to be at the risk of occupational HBV. Health education highlighting occupational risk of HBV, accessibility of vaccine and mandatory vaccination of HCW is recommended to increase HBV vaccine compliance among HCW.

Antibody to Hepatitis B Surface Antigen in Vaccinated Health Care Workers.

BACKGROUND: Health care workers (HCWs) in Armed Forces are immunised against Hepatitis B virus (HBV), however they are not subjected to anti-HBs (antibody to Hepatitis B surface antigen) assessment after primary vaccination. The present study was undertaken to determine the protection offered by HBV vaccine in HCW. METHODS: Cross-sectional study was carried out at tertiary care hospital. A total 146 HBV vaccine compliant HCW were evaluated for quantitative anti-HBs by enzyme immune assay. RESULT: 129 (88.4%) subjects had protective levels of anti-HBs. Higher age at vaccination was an important risk factor in low vaccine response. Decline in anti-HBs with time was evident. Anti-HBs levels were more than 10mIU/ml in subjects even after 11 years of primary vaccination. There was no difference in protection in booster and non booster groups. CONCLUSION: Age is the most important factor in HBV vaccine response. Booster dose of HBV vaccine is not necessary in healthy HCW for atleast ten years after primary vaccination. The study recommends early primary vaccination of HCW and 'initial' anti-HBs assay for confirmation of vaccine response.