Incidence of -lactamase producing organisms causing various infections and comparison of their antimicrobial susceptibility testing.

Higher generation cephalosporins, resistant to ß-lactamases were designed to combat bacterial resistance to first generation ß-lactam antibiotics. This led to the emergence of extended spectrum ß-lactamases (ESBLs), which conferred bacterial resistance to these drugs. Now, combination drugs employing a ß-lactam drug + a ß-lactamase inhibitor (Clavulanate, Sulbactam, Tazobactam) are used against ESBL-producing pathogens. This study aimed to evaluate the efficacy of these combination drugs against ESBL-producers and also screening for the presence of inducible AmpC ß-lactamase producers. Enterobacteriaceae family culture isolates exhibiting resistance to the 2nd / 3rd generation cephalosporins by the Disk Agar Diffusion test were tested for ESBL production by the Double Disk Synergy Test. Staphylococcal species culture isolates were tested for ßlactamase production by the Nitrocefin spot test. The Disk Antagonism test was used to screen for the presence of inducible Amp C ß-lactamase producers. The combination drugs included in this study were Cefepime/Tazobactam, Cefoperazone/Sulbactam, Cefotaxime/ Sulbactam, Ceftriaxone/ Sulbactam & Ceftriaxone/ Tazobactam. 128 clinical isolates were tested for ß-lactamase activity. Of the 26 S.aureus isolates, 88.4% (23) were ß-lactamase positive and 57.1 % coagulase negative Staphylococci were positive. Amongst Enterobacteriaceae family, 67.8% of E.coli; 53.1% of K.pneumoniae and 53.8% of Proteus species were confirmed ESBL producers. For E.coli, the best drug was Cefepime/ Tazobactam. All drugs were effective against Proteus spp. K.pneumoniae and S.aureus isolates were resistant to these drugs due to the production of AmpC ß-lactamases. 3.4% of E.coli, 4.5% of S.aureus and 14.2% of Proteus spp were confirmed inducible AmpC ß-lactamase producers.

In vitro study to compare sensitivity of amoxicillin+clavulanic acid and cefpodoxime+clavulanic acid among beta-lactamase positive clinical isolates of gram-positive and gram-negative pathogens.

The present study was carried out to compare the in vitro sensitivity of cefpodoxime + clavulanic acid and amoxicillin + clavulanic acid against 55 Gram-positive and 123 Gram-negative beta-lactamase positive clinical isolates. Micro-organisms isolated from different clinical specimens were tested for beta-lactamase/ESBL by using nitrocefin disc test and for metallo beta-lactamase by using double disc synergy test. A total of 299 (93 Gram-positive and 206 Gram-negative) clinical isolates were tested for beta-lactamase. Among 93 Gram-positive clinical isolates 25 (78.12%) out of 32 coagulase positive S. aureus, 23 (60.52%) out of 38 coagulase negative S aureus, 7 (63.63%) out of 11 enterococci and 0 (0%) out of 12 Strept pneumoniae were positive for beta-lactamase /ESBL. Notably Strept pneumoniae was found to be beta-lactamase/ESBL negative. Among 206 Gram-negative clinical isolates, 25 (69.44%) out of 36 acinetobacter spp, 20 (41.66%) out of 48 Branhamella catarrhalis, 24 (64.86%) out of 37 E. coli, 7 (46.66%) out of 15 H influenzae and 22 (62.85%) out of 35 proteus were positive for beta-lactamase/ ESBL/metallo beta-lactamase. Positive strains were tested for comparative sensitivity to amoxicillin+ clavulanic acid and cefpodoxime+clavulanic acid by Kirby Bauer disc diffusion method. As regards comparative sensitivity among beta-lactamase/ESBL positive Gram-positive strains, 84% and 92% strains of coagulase positive S aureus, 65.21% and 86.95% strains of coagulase negative S. aureus, 83.33% and 100% strains of Strept pneumoniae and 71.42% and 100% strains of enterococci were found sensitive to amoxicillin +clavulanic acid and cefpodoxime + clavulanic acid respectively. Sensitivity to amoxicillin+ clavulanic acid and cefpodoxime +clavulanic acid among beta lactamase/ESBL positive Gram-negative strains of acinetobacter spp, Branhamella catarrhalis, E. coli, H. influenzae and proteus spp were found to be 20% and 28%, 100% and 100%, 50% and 75%, 71.42% and 100%, 50% and 68.18% respectively. This study demonstrated that cefpodoxime +clavulanic acid combination has more potent in vitro activity in comparison to amoxicillin+ clavulanic acid combination against beta-lactamase producing strains of Gram-positive and Gram-negative bacteria. Given this broad spectrum of activity, cefpodoxime+clavulanic acid appears well suited for use in the treatment of a variety of healthcare-associated infections.

Polymerase chain reaction for the rapid diagnosis of tuberculous meningitis.

(i) AIM OF THE STUDY: The study was carried out with the aim to evaluate a polymerase chain reaction (PCR) based on the amplication of a 169 bp DNA fragment specific for the Mycobacterium tuberculosis complex for the rapid diagnosis of tuberculous meningitis (TBM). (ii) METHODOLOGY: A total of 105 CSF specimens from clinically suspected cases of TBM were studied. Clinical details of the cases and cytochemical parameters of the CSF specimens were recorded. In addition to the 105 specimens, 10 CSF specimens from cases other than TBM, 4 non-mycobacterial culture isolates (1 strain of E. coli, 1 strain of Proteus species and 2 strains of Salmonella species) and 1 sample of sterile distilled water were processed as negative controls. For positive control standard culture of Mycobacterium tuberculosis H37Rv was processed with every batch of specimens. Besides PCR, smear for AFB by the Ziehl Neelsen Carbol Fuchsin (ZNCF) and the fluoro chrome method and culture on LJ medium was also carried out. (iii) RESULTS: By PCR, 31.42% specimens were found positive, whereas by conventional culture on LJ medium only 3.8% specimens were positive. Only 1.9% specimens were found to be smear positive by the fluorochrome staining method, while none was positive by the ZNCF method.The PCR results showed complete correlation with the clinical findings of the patients. (iv) CONCLUSION: The PCR was found to be superior to the currently available techniques for the diagnosis of tuberculous meningitis in terms of sensitivity, specificity and rapidity and could play a critical role in the diagnosis of suspected cases.

Polymerase chain reaction based diagnosis of systemic fungal infections and sensitivity testing of the fungal isolates.

PURPOSE: To highlight the usefulness of polymerase chain reaction (PCR) for the rapid diagnosis of systemic fungal infections. METHODS: Clinical samples were collected from 50 clinically suspected cases of systemic mycosis and subjected to smear, culture, antifungal sensitivity and PCR (based on 18S rRNA gene). RESULTS: Of the 50 clinical specimens tested by PCR, 39 were found to be positive. PCR gave more positive results than smear and culture examination. Out of the 50 clinical specimens 35 were found to be fungal culture positive. The sensitivity testing results of these fungal isolates showed that there was a good correlation between the in vitro results and the clinical response of the patient to antifungal therapy. Itraconazole exhibited maximum antifungal activity followed by fluconazole, ketoconazole and amphotericin B. CONCLUSIONS: PCR technology provides rapid and accurate diagnosis of fungal infection, however, it must be used with caution to avoid false positives.

Chromogenic agar for rapid presumptive identification of yeast species:--a preliminary report.

A chromogenic medium for the rapid presumptive identification of yeasts was devised and studied. The medium was found to be effective in differentiating the yeast species studied on the basis of colony colour. With further modification the medium can be used as a primary isolation medium.

Klebocin typing of Klebsiella species isolated from nosocomial infection in intensive care unit.

Klebocin typing and antibiotic resistance have been studied for 518 strains of Klebsiella pneumoniae, [106 from intensive care unit (ICU) sites, 182 from ICU staff flora, 192 from patient flora and 38 from clinical specimens]. The overall typability was 71.62%. The most common mnemonic types among various sources were 111, 211, and 112. Of the total strains tested, 28.37% strains were found to be untypable. These strains are labelled as "444". When klebocin typing was used in association with antibiogram, in 86.84% cases of clinical infection probable source of infection could be detected. Thus a combination of two typing methods poses a significant contribution in epidemiological studies.

Prevalence of hepatitis C virus (HCV) infection in Mumbai.

A study was carried out to determine the prevalence of Hepatitis C virus (HCV) in Mumbai among certain high risk groups such as renal transplant recipients, multitransfused and haemodialysis patients; professional and voluntary blood donors and viral hepatitis cases for comparison. Repeated testing of 602 subjects for antibodies to HCV using a second generation ELISA assay (Abbott, USA) showed an overall prevalence of 16.9%. We found 36.4% of multitransfused patients, 27.8% of renal failure cases and 26.2% of renal transplant recipients to be seropositive. Voluntary blood donors in our series showed a surprisingly high prevalence of 15.9%, and this group needs further investigation. Fifty-six of these sera (of which 45 were anti-HCV positive) were tested for HCV RNA by PCR and 14(31.1%) of the seropositive samples were also HCV RNA positive. The present investigation not only shows a high prevalence of HCV in the study groups but also proves the presence of HCV genomes in a significant proportion.

Tuberculosis screening: usefulness of new KREATECH IgA ELISA test.

A total of 71 sera from 15 proved cases of pulmonary tuberculosis, 2 cases with doubtful radiological report and 54 suspected cases, contacts, donors etc. were subjected to Elisa IgG, IgM and IgA tests for tuberculosis, with a view to comparing the merits of IgA test with those of IgG and IgM. Kreatech IgA test which is claimed to indicate presence of active tuberculosis was positive in 13 of the proved cases and negative in both the doubtful cases. These preliminary results indicate that KREATECH IgA is a promising new ELISA test which can be a useful laboratory aid in the diagnosis of active tuberculosis, both pulmonary and extrapulmonary, for screening of suspected cases, and for monitoring cases undergoing therapy.