Role of quantitative endotracheal aspirate and cultures as a surveillance and diagnostic tool for ventilator associated pneumonia: a pilot study.

BACKGROUND: Accurate diagnosis and appropriate treatment of ventilator associated pneumonia (VAP) is crucial for good outcomes. Endotracheal suctioning is performed in ventilated patients as part of routine care and for tracheal toileting. AIM: We evaluated if quantitative endotracheal aspirate (ETA) was a suitable alternative to bronchoalveolar lavage (BAL) for suspected VAP. In addition we assessed if surveillance ETA guided antibiotic selection for subsequent VAP. SETTING AND DESIGN: Prospective study in the surgical intensive care unit (ICU) of a tertiary hospital in India. MATERIALS AND METHODS: Two hundred consecutive patients with mean (standard deviation) APACHE II score of 12.3+/-5 and requiring mechanical ventilation beyond 48 hours underwent surveillance ETA cultures. A second ETA and BAL were performed if the patient developed features of VAP. The threshold for microbiological diagnosis of VAP was taken as 10 5 colony forming units/ml (cfu/ml) for ETA and 10 4 cfu/ml for BAL. STATISTICAL ANALYSIS: The sensitivity and specificity of surveillance and concurrent ETA aspirate cultures were compared with BAL cultures. RESULTS: VAP was suspected clinically and corroborated radiologically in 27/177 patients (15.3%). Although microbiological support for VAP was obtained by ETA in 19 patients, bronchoscopy was possible only in 13 patients, 8 of whom had isolates at significant threshold. Of the 16 organisms isolated from BAL, 11 were of significant threshold with 9/11 (82%) BAL isolates having a similar antibiogram to a concurrent ETA. Only one BAL isolate (9%), at significant threshold, was not isolated on a concurrent ETA. On the other hand just 6/11 BAL isolates (55%) had an identical antibiogram to surveillance ETA. BAL had 3 additional isolates (27%) at significant threshold not isolated on surveillance ETA. CONCLUSIONS: Concurrent quantitative ETA could substitute BAL cultures for VAP. Surveillance ETA at 48 hours of ventilation does not appear to assist with antibiotic selection for a subsequent VAP.

Dynamics of anti-M antibody response in a mouse model following intranasal infection with group A Streptococcus M-18.

Dynamics of anti-M antibody response following intranasal infection with group A Streptococcus (GAS) M-18 were investigated in a Swiss albino mouse model. Mice arranged in three groups were inoculated intranasally with 2.0x10(7) c.f.u. ml-1 of GAS M-18 on 1, 2 alternate and 3 alternate days. Plasma collected from the retro-orbital plexus was tested for antibodies by an in-house indirect ELISA. The antibody titres of the plasma samples varied from 1 : 8 to 1 : 1024 in the 1 day dose, from 1 : 4 to 1 : 256 in the 2 day dose and from 1 : 4 to 1 : 128 in the 3 day dose. Peak titres were seen on day 42 or 56 and in all cases the titres had declined by day 84. Swiss albino mouse can thus serve as a useful animal model to study different aspects of type-specific anti-M immune responses against GAS disease when designing candidate streptococcal vaccines.

Antimicrobial susceptibility patterns of clinical isolates of Staphylococcus aureus in Nepal.

Isolates of Staphylococcus aureus (n = 117) from patients attending a tertiary care centre in western Nepal were tested for susceptibility to penicillin, oxacillin, gentamicin, erythromycin and ciprofloxacin. Eighteen (15.4%) were methicillin-resistant. Susceptibility among methicillin-resistant isolates varied from 0% (penicillin) to 16.6% (erythromycin and gentamicin), but varied among methicillin-susceptible isolates from 39.4% (penicillin) to 97.0% (ciprofloxacin). Fourteen (77.8%) of the methicillin-resistant isolates were resistant to all agents tested. Implementation of an appropriate antibiotic policy would reduce the risk of further development of antimicrobial resistance.

Increasing erythromycin resistance among group A streptococci causing tonsillitis in a tertiary care hospital in southern India.

Group A streptococci (GAS) (n = 1313) isolated from patients with clinical symptoms of pharyngitis or tonsillitis attending a tertiary care hospital in southern India during 1986-2002 were tested for susceptibility to penicillin and erythromycin. The overall erythromycin resistance rate was 2.7% (n = 36). During 1986-1993, erythromycin resistance was observed in only one (2%) isolate in 1987, but reappeared in 1994 (2.7%), increased to 5.8% in 1999, and reached a maximum frequency of 13.8% in 2002. All isolates were susceptible to penicillin. The data indicate the need for continued surveillance of susceptibility patterns among GAS isolates in order to monitor the development of antibiotic resistance.

Outcome of bacterial culture from mastoid granulations: is it relevant in chronic ear disease?

OBJECTIVE: To detect the presence of bacteria in mastoid granulations and compare its prevalence in both types of chronic suppurative otitis media (CSOM). To find out if stage of disease activity, age, duration of disease, and aditus patency relate to obtaining positive cultures. STUDY DESIGN AND SETTING: A prospective, parallel group study done at a tertiary care referral centre. Mastoid granulations from 79 patients with CSOM undergoing mastoidectomy were processed for anaerobic and aerobic bacteria. RESULTS: Aerobes were isolated from 57.55 per cent of the tubotympanic and 74.4 per cent of atticoantral disease (p=0.18). Anaerobic cultures were positive in one case from each group. Monomicrobial growth was detected in 37.5 per cent of tubotympanic and 48.5 per cent of atticoantral disease. Polymicrobial growth occurred in 20 per cent and 25.6 per cent in the tubotympanic and atticoantral groups, respectively. The predominant aerobic isolate was coagulase negative Staphylococcus, followed by Pseudomonas aeruginosa, Staphylococcus aureus, non-fermenting Gram-negative bacteria, Enterobacter and Enterococcus, Proteus species, Citrobacter, non-pathogenic Neisseria, aerobic spore formers were grown only in atticoantral disease. A single isolate of Aspergillus was grown. Correlating the state of disease activity of the ears with positive mastoid granulation cultures, six out of the eight inactive ears were culture positive along with seven out of the nine active and 10 out of the 23 quiescent ears. Positive mastoid granulation cultures were obtained in 60 per cent of those with blocked aditus and 42.9 per cent with patent aditus. CONCLUSION AND SIGNIFICANCE: In this study, we found that mastoid granulations are not sterile but harbour polymicrobial pathogens. Positive cultures were obtained irrespective of stage of disease activity, age, duration of disease and aditus patency. The pattern of organisms cultured from safe and unsafe CSOM and also from ears in active, quiescent and inactive stages, were similar. These findings suggest that these organisms may be responsible for mastoid granulations. We also noted that positive cultures had no statistical correlation with aditus patency and duration of disease. We suggest further studies to evaluate the significance of asymptomatic mastoid granulations harbouring organisms and whether opening the mastoid antrum and achieving aditus patency, irrespective of the stage of disease activity, will help improve the long-term surgical outcome and also prevent recurrence of ear discharge.

The reliability and rapidity of the coagglutination technic and its comparison with precipitin technic in the grouping of streptococci.

Three methods of the grouping of 170 strains of beta-hemolytic streptococci belonging to Groups A, B, C, F, and G by capillary and agar-gel precipitation using Lancefield extract and by coagglutination of antibody-coated protein A-containing staphylococci were compared. Capillary and agar-gel precipitin technics correctly grouped all 170 strains, with no cross-reaction. One hundred sixty-nine out of the 170 strains were also correctly grouped by the coagglutination technic, and the one strain with a cross-reaction was correctly grouped after blood--agar subculture. Although 20 of the 170 strains showed minor cross-reactions by the coagglutination technic, the specific groups were easily and unquestionably detected, and the minor cross-reactions were easily overcome. A rapid method of grouping by coagglutination technic using 4--6-hour broth culture, done on 75 strains, showed that 73 strains could be correctly grouped by the rapid method and two after overnight incubation. Thus, the coagglutination technic of grouping was found to be easy, reliable, and economical, and could be adopted in any routine diagnostic laboratory as a rapid grouping procedure.

Investigation of antimicrobial use pattern in the intensive treatment unit of a teaching hospital in western Nepal.

BACKGROUND: Inappropriate use of antimicrobials is of special importance in the intensive treatment unit because of the large number of drugs prescribed, the chance for drug errors, and the likelihood of development of drug resistance. METHODS: A total of 297 records of patients admitted to the intensive treatment unit of the Manipal teaching hospital, a tertiary care hospital in Pokhara, western Nepal, were studied to determine the prescribing frequency and rationality of use of antimicrobials. Patient outcome, duration of stay in the intensive treatment unit, and the age and sex distribution of the patients were also studied. RESULTS: Mean+/-SD drugs per patient was 3.4+/-1.8. About half (50.2%) of the patients received an antimicrobial; 84.6% of the antimicrobials were used without obtaining bacteriologic evidence of infection. The commonest organisms isolated on culture were Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae, and Staphylococcus aureus. A total of 28.9% of the antimicrobials were prescribed for lower respiratory tract infections on the basis of the putative site of infection; 61.9% of the antimicrobials were prescribed by the parenteral route and mainly the older generation of antimicrobials were used. In 39 of the 149 patients prescribed an antimicrobial, the use was irrational. CONCLUSIONS: Prescriber education to improve prescribing patterns and regular auditing of antimicrobial prescriptions to prevent their inappropriate use and unnecessary cost to the patients are required. The high percentage of inappropriate use of antimicrobials raises concerns about the development and spread of drug resistance, which must be addressed.

Use of enzymes in typing group A beta-haemolytic streptococci.

A series of 698 strains of group A beta-haemolytic streptococci (GAS) isolated from children with streptococcal pyoderma was tested for production of serum opacity factor (OF) and nicotinamide adenine dinucleotide glycohydrolase (NADase). OF was produced by 37% of strains and 40% produced NADase. Classification based on various combinations of OF and NADase reactions showed that 58% belonged to enzyme group el and 34% to e2. Correlation with T and M types showed the possible use of this means of classification as an epidemiological marker for GAS. The specificity of such a system in the further classification of various T types of GAS in epidemiological studies, in the light of antigenic variation among M types, is described.

Typing of Acinetobacter baumannii isolated from hospital-acquired respiratory infections in a tertiary care centre in southern India.

In an attempt to define the epidemiology of Acinetobacter baumannii infection, 27 isolates, obtained from hospital-acquired respiratory infections, were typed using random amplified polymorphic DNA (RAPD) profile and antimicrobial susceptibility patterns. Ten different patterns were obtained with ERIC2 primer: 14 isolates had a similar profile representing a single strain. Within RAPD types, isolates could be further classified based on their antibiogram; however, strains of different types had similar antibiograms. This study showed that many different genetic types of A. baumannii are prevalent in our hospital. While antibiograms alone are not sufficiently discriminatory, RAPD typing helps in identifying outbreaks and in assessing infection control procedures within a hospital.

Changing pattern of primary glomerulonephritis in a south Indian hospital.

Data were reviewed on 2805 patients with primary glomerulonephritis admitted to a south Indian hospital in 1972-1987. A decrease in the proportion of endocapillary proliferative, crescentic and mesangial proliferative types was noted. There was also a decrease in group A beta-haemolytic streptococcal isolates among the 24,657 throat swab cultures made during the same period. This suggests a decreasing prevalence of nephritogenic streptococcal infections in this tropical region.

Speciation of viridans streptococci & their significance in human infections.

Sixty strains of viridans streptococci recovered, from various infections, encountered in a large referral Hospital in Tamil Nadu (south India) from December 1983 to May 1985 were characterised by conventional tests. Of these, 57 (95%) belonged to four species viz., Sanguis II, Mitis, Intermedius and Constellatus. Of the 40 strains that were assessed for their clinical significance, 23 (57.5%) were found to be either significant or of suggestive significance. The study suggested viridans streptococci are not particularly virulent pathogens. But local/systemic factors were found to predispose the subjects to this infection.

Long-term preservation of streptococci.

Strains of 12 T types of group A streptococci preserved by sand desiccation and stored at 4 degrees to 10 degrees C were regularly sub-cultured to check their viability. For this, streptococci coated onto sand particles mixed with sterile sheep blood were inoculated into Todd-Hewitt broth with added blood and incubated for 24 to 48 h. Checking for viability every six months showed that group A streptococci could be preserved by this method for 21 yr. Our study shows that sand desiccation is a convenient and cheap method for the long-term preservation of streptococci in laboratories where other methods of preservation are not feasible on a regular basis.

Identification of gram positive cocci isolated from urine.

A total of 195 strains of Gram positive cocci isolated from urine, in pure culture and in counts of > 10(3) colony forming units/ml, during January-September 1992, were speciated using schema recently described by Facklam and Washington, and Kloos and Lambe. Seventy three (85%) of the 86 enterococci were identified as Enterococcus faecalis while 11 (13%) were E. faecium. Eighteen (29%) of the 62 staphylococcal isolates were Staphylococcus aureus; 20 (45%) of the 44 coagulase negative staphylococci were speciated as Staph. haemolyticus. Of the 47 strains of beta haemolytic streptococci isolated, 45 (96%) were group B; one was group G and the other group F. Our results show the diverse species of Gram positive cocci associated with bacteriuria and the need to speciate them in a diagnostic laboratory. In the context of a larger number of tests required for the speciation of Gram positive cocci, we recommend a simplified scheme which we found feasible on a routine basis.

Detecting mycobacteraemia for diagnosing tuberculosis.

BACKGROUND & OBJECTIVES: In human immunodeficiency virus (HIV) infected persons with pulmonary tuberculosis (TB), sputum may not always show acid fast bacilli (AFB). Moreover, in most cases of suspected extrapulmonary TB (irrespective of HIV status) mycobacteria-containing material is not readily available for investigation. This study evaluated whether blood culture for Mycobacterium tuberculosis bacteraemia (mycobacteraemia) help in diagnosing TB in such cases. METHODS: A total of 93 consecutive subjects with a clinical diagnosis of tuberculosis with or without laboratory confirmation, 42 with and 38 without coexisting HIV infection, and 13 patients with HIV infection without clinical evidence of TB were enrolled. Mycobacterial blood cultures were done using lysis centrifugation technique followed by subculturing onto the modified Lowenstein-Jenson medium (LJ-1) and Selective Kirchner's medium followed by subculturing onto the modified Lowenstein-Jenson medium (LJ-2, LJ-3). RESULTS: Of the 15 (16.2%) subjects with evidence of mycobacteremia in 4 (26.7%) blood was the first/ only source of diagnosing TB. Among 80 patients with clinical diagnosis of TB whether supported by laboratory tests or not, 14 (17.5%) had mycobacteraemia. Among the 21 HIV infected patients with laboratory proven TB, 9 (43%) had mycobacteraemia. INTERPRETATION & CONCLUSION: Blood culture appears to be a useful additional test to diagnose TB in persons with HIV infection. In patients without HIV infection, but with clinical picture compatible with TB, blood culture for mycobacteraemia may occasionally help in the diagnosis. We recommend the use of the lysis centrifugation technique followed by direct smear of the sediment along with inoculation of the sediment into both modified Lowenstein-Jenson medium and the Selective Kirchner's medium with subsequent subculturing onto the modified Lowenstein-Jenson medium for mycobacterial blood culture for detecting mycobacteraemia.

Biological characterisation of group F streptococci causing human infections.

Fifty five strains of group F streptococci (GFS) isolated from clinical samples of 53 patients with diverse diseases, were characterised by a battery of physiological tests. Among them 37 (67%) were Streptococcus anginosus F, 14 (25%) were Strep. intermedius, two of which were mannitol positive and 4 (7%) were Strep. constellatus. Determination of minimum inhibitory concentrations of penicillin, erythromycin, ampicillin, gentamicin and cefazolin showed that despite their biochemical heterogeneity, all strains were uniformly susceptible to these antibiotics. Except for bacteraemia, other diseases due to GFS responded well to surgical drainage and/or antibiotics.

An outbreak of post-streptococcal reactive arthritis.

We describe an outbreak of an illness with fever, mono-, pauci- or polyarticular arthritis, and high antideoxyribonuclease B (ADNB) titres in 11 patients. Two patients had concomitant non-purulent conjunctivitis and one had endogenous endophthalmitis. There was no clinical or echocardiographic (6 patients) evidence of carditis. Blood culture grew Group A beta haemolytic streptococci in one patient. A simultaneous synovial fluid culture in this patient and similar cultures in four more patients yielded no microorganism. Most patients recovered completely, but one developed rheumatoid factor negative spondyloarthropathy. Monoarticular arthritis in several patients, the absence of carditis, and the presence of high ADNB titres without high anti-streptolysin O titres indicate that this was not acute rheumatic fever but post-streptococcal reactive arthritis (PSRA).

Changing patterns of group B streptococcal serotypes associated with human infections.

One hundred strains of group B streptococci (GBS) isolated from diverse clinical specimens of patients seen in our hospital were subjected to serotyping by an indigenously prepared coagglutination system. Serotype NT/c was the most predominant (24%), followed by Ia (23%), II/c (12%) and Ib (11%). Type Ia was the most predominant in all specimens except genital samples where NT/c was the most predominant. Comparison of the distribution of serotypes identified during 1975-78 with that of the present study showed a great increase in the prevalence of types NT/c, II/c and Ia and a dramatic decline of types III, Ia/c and Ib. Despite the inclusion of reagents for newer serotypes, IV and V two strains were nontypable indicating the prevalence of hitherto unidentified GBS serotypes in our community.

Prevalence of pneumococcal serotypes in invasive diseases in southern India.

Forty two pneumococcal strains obtained in Vellore, Tamil Nadu, from 42 patients with invasive diseases, namely pneumonia, meningitis, or peritonitis were typed. Over one-third of pneumococci in children and nearly half in adults were serotype followed by serogroups/types 5, 6 and 7 which were most common in children and adults taken together. These 4 serogroups/types accounted for 11 (79%) of 14 strains in children and 20 (71%) of 28 strains in adults. The remaining 11 strains belonged to 8 serogroups/types, namely 3, 4, 10, 11, 12, 13, 19 and 20.

Maxillary sinus fusariosis in immunocompetent hosts.

We report the first known cases of Fusariosis of maxillary sinus with granuloma and oro-antral fistula in two immunocompetent hosts. Fusarium solani was demonstrated in the direct microscopic examination and isolated in heavy growth from the biopsy materials. Both these patients were successfully treated with oral ketoconazole (200 mg daily) for three weeks followed by a Caldwell-Luc operation. Ketoconazole was continued for two months post-operatively.

Systemic bacterial infections in bone marrow transplant patients.

The clinical microbiology department at CMC&H, Vellore in conjunction with the haematology department carries out routine surveillance of patients admitted to the hematology department. Since 1994 in a sample population of 55 patients with various underlying clinical conditions who have had bone marrow transplant, sepsis was observed in 16 patients (29%). The predominant Gram negatives associated with sepsis were non-fermenting Gram negative bacilli and all the 5 Gram positives were coagulase negative staphylococci. These organisms were susceptible to most of the routinely used antimicrobial agents. Continued surveillance is needed to determine changing trends with respect to organisms causing systemic infections and their susceptibility to antimicrobials.