Evaluation of phenotypic tests for detection of Klebsiella pneumoniae carbapenemase and metallo-beta-lactamase in clinical isolates of Escherichia coli and Klebsiella species.

Context: Carbapenemase production is an important mechanism responsible for carbapenem resistance. Aims: Phenotypic detection and differentiation of types of carbapenemase in carbapenem resistant Enterobacteriaceae is important for proper infection control and appropriate patient management. Settings and Design: We planned a study to determine the occurrence of Class A Klebsiella pneumoniae carbapenemase (KPC type) and Class B Metallo-β-lactamase (MBL type) carbapenemase in hospital and community. Materials and Methods: Clinical isolates of Escherichia coli and Klebsiella species and simultaneously evaluate different phenotypic methods for detection of carbapenemases. Results: It was observed that 20.72% clinical isolates of E. coli and Klebsiella spp. were resistant to carbapenem on screening of which, 14.64% were E. coli and 29.69% were Klebsiella spp. Using phenotypic confirmatory tests the occurrence of carbapenemase production was found to be 87.01% in E. coli and 91.51% in Klebsiella spp. using both modified Hodge test (MHT) and combined disk test (CDT) using imipenem-ethylenediaminetetraacetic acid. Conclusions: Both MBL and KPC type carbapenemases were seen among clinical isolates of E. coli and Klebsiella spp. CDT is simple, rapid and technically less demanding procedure, which can be used in all clinical laboratories. Supplementing MHT with CDT is reliable phenotypic tests to identify the class A and class B carbapenemase producers.

Extended spectrum beta lactamase producing Proteus penneri: A rare missed pathogen.

Indole negative Proteus species are invariably incorrectly identified as Proteus mirabilis, often missing out isolates of Proteus penneri. We report a case of extended spectrum beta lactamase producing and multidrug-resistant P. penneri isolated from pus from pressure sore of a patient of road traffic accident. Correct and rapid isolation and identification of such resistant pathogen are important as they are significant nosocomial threat.

Genotype MTBDR plus assay for molecular detection of rifampicin and isoniazid resistance in Mycobacterium tuberculosis.

Aim: This study was performed for the rapid identification of Mycobacterium tuberculosis complex and its resistance to rifampicin and isoniazid, directly from the sputum samples of pulmonary tuberculosis patients. Materials and Methods: A commercially available genotype MTBDR plus assay was used for the identification and detection of mutations in Mycobacterial isolates. A total of 100 sputum samples of pulmonary tuberculosis patients were analyzed by using the genotype MTBDR plus assay. The MTBDR plus assay is designed to detect the mutations in the hotspot region of rpoB gene, katG and regulatory region of inhA gene. Results: The genotype MTBDR plus assay detected 22% multidrug resistant (MDR), 2% rifampicin (RMP) monoresistant and 1% isoniazid (INH) monoresistant isolates. In 22 MDR isolates, the codons most frequently involved in RMP-associated mutations were codon 531 (54.55%), 516 (31.82%) and 526 (13.63%), and 90.90% of MDR isolates showed KatG S315T mutations and 9.1% showed inhA C-15T mutations associated with INH resistance. Conclusion: The new genotype MTBDR plus assay represents a rapid, reliable tool for the detection of MDR-TB, wherein results are obtained in 5 h allowing early and appropriate treatment, which is essential to cut the transmission path and reduce the spread of MDR-TB. The genotype MTBDR plus assay can readily be included in a routine laboratory work for the early diagnosis and control of MDR-TB.

Evaluation of phenotypic tests for the detection of AmpC beta-lactamase in clinical isolates of Escherichia coli.

Background: AmpC beta lactamases are cephalosporinases that confer resistance to a wide range of beta lactam drugs thereby causing serious therapeautic problem. As there are no CLSI guidelines for detection of AmpC mediated resistance in Gram negative clinical isolates and it may pose a problem due to misleading results, especially so in phenotypic tests. Although cefoxitin resistance is used as a screening test, it does not reliably indicate AmpC production. Materials and Methods: We planned a study to determine the occurrence of AmpC beta lactamase in hospital and community, clinical isolates of Escherichia coli and simultaneously evaluate different phenotypic methods for detection of AmpC beta lactamases. Results: It was observed that 82.76% isolates were ESBL positive and 59% were cefoxitin screen positive. Using phenotypic confi rmatory tests the occurrence of Amp C beta lactamases was found to be 40% and 39% by inhibitor based method using boronic acid (IBM) and modifi ed three dimensional test (M3D) respectively. Conclusion: Both the test showed concordant result. Co-production was observed in 84.62% isolates Screening of ESBL and Amp C can be done in routine clinical microbiology laboratory using aztreonam and IBM respectively as it is a simple, rapid and technically less demanding procedure which can be used in all clinical laboratories.

Prevalence of HIV, Hepatitis B and Hepatitis C infection in Thalassemia major patients in tertiary care hospital, Gujarat.

Background: Children suffering from beta thalassemia major, due to various genetic defects, have deficient synthesis of ß globin chain of Hemoglobin. This leads to severe anemia, general fatigue and debility asking for repeated or frequent blood transfusion. On the other hand repeated blood transfusions such expose them to dangerous infections such as HIV, HBV and HCV. Aim: The aim of this study was to determine the prevalence of HIV, HBV and HCV infection among thalassemia major patients in an apex tertiary care hospital of Gujarat in west India. Materials and methods: Data were obtained from 100 ß thalassemia major patients attending thalassemia clinic for blood transfusion at regular interval in an apex tertiary care hospital of Gujarat between April 2008 and September 2008. Their laboratory results were subsequently analyzed. Results: Out of 100 patients 65 and 35 were male and female respectively. 18 (18%) patients were found Anti HCV Ab positive, 6 (6%) were found HBsAg positive and 9(9%) patients were Anti HIV 1 and or 2 Ab positive. Older age, more number of transfusions were associated with increased chances of the test to come positive suggestive of infection with respective virus. Completion of vaccination against HBV, completely or partially, was associated with less chances getting infection with HBV Conclusion: The prevalence of HCV infection is much higher compared to HBV and HIV infection due to possibly infected blood transfusion among thalassemia major patients. Screening of Anti HCV Ab detection with highly sensitive and specific test for donated blood is mandatory. Techniques like P24 Antigen detection or RT-PCR should be introduced to shorten the window period for detection of HIV infected donated blood.

Biological warfare, bioterrorism and biodefence.

Biological warfare is the intentional use of micro-organisms and toxins to produce disease and death in humans, livestock and crops, their attraction in war, and for use in terrorist attacks is attributed to various unique features. Biological weapons (BWs) can be disseminated by aerosol sprays, explosives or food and water contamination. Bws can strike suddenly without any warning and inflict considerable mortality and morbidity that can continue for a long period, such attacks may create high level of panic, environment contamination and extreme pressures on emergency health services. Bioterrorism is the use of bws in terrorism. Current concerns regarding the use of bws result from the increasing number of countries that are engaged in the proliferation of such weapons and their acquisition by terrorist organizations. The need of the hour is to develop biodefence by full international cooperation and to educate the likely target populations about precautions and protective measures to be taken in such attacks.

Physician accessories: Doctor, what you carry is every patient's worry.

Background: Nosocomial infections are on the rise worldwide and many a times they are carried by the health care personnel. Accessories used by physicians and healthcare personnel can be a potential source of nosocomial infection. Materials and Methods: We designed a survey with the aim to investigate the prevalence of microbial flora of accessories such as pens, stethoscopes, cell phones and white coat used by the physicians working in a tertiary care hospital. Observations: It was observed that 66% of the pens, 55% of the stethoscopes, 47.61% of the cell phones and 28.46% of the white coats used by the doctors were colonized with various microorganisms. Staphylococcus spp. was the predominant isolate followed by Escherichia coli. Methicillin resistance in Staphylococcus aureus was also found, which was a matter of concern. Conclusions: Awareness of appropriate hand hygiene is important in order to prevent potential transmission to patients.

Beta-lactamase producing Pseudomonas aeruginosa in hospitalised patients.

Beta lactamase continues to be the leading cause of resistance to beta lactam antibiotics in gram-negative bacteria. A total of 50 clinical isolates of Pseudomonas aeruginosa were studied to determine the prevalence of ESBL production in hospital strains and also to study their susceptibility to various other antimicrobial agents. ESBL production was observed in a total of 18/50 (36%) of cases. Most of the ESBL positive isolates showed resistance to 3rd generation cephalosporins including multidrug resistance (MDR) to antibiotics like piperacillin, nalidixic acid, ciprofloxacin, levofloxacin, gentamicin and tobramycin. The ESBL producers however showed good susceptibility to drugs like meropenem, gatifloxacin and amikacin.